阅读说明：本技术 用于显示器的堆叠和具有其的显示设备 (Stack for display and display device having the same ) 是由 张成逵 李豪埈 蔡钟炫 李贞勋 于 2019-01-03 设计创作，主要内容包括：一种用于显示器的发光二极管像素,所述发光二极管像素包括第一子像素、第二子像素和第三子像素,所述第一子像素、所述第二子像素和所述第三子像素中的每一个包括：第一LED子单元,其包括第一类型的半导体层和第二类型的半导体层；第二LED子单元,其设置在所述第一LED子单元上,并包括第一类型的半导体层和第二类型的半导体层；第三LED子单元,其设置在所述第二LED子单元上,并包括第一类型的半导体层和第二类型的半导体层,其中,所述第一子像素的所述第二LED子单元和所述第三LED子单元是电浮置的,所述第二子像素的所述第一LED子单元和所述第三LED子单元是电浮置的,所述第三子像素的所述第一LED子单元和所述第二LED子单元是电浮置的。(A light emitting diode pixel for a display, the light emitting diode pixel comprising a first sub-pixel, a second sub-pixel, and a third sub-pixel, each of the first sub-pixel, the second sub-pixel, and the third sub-pixel comprising: a first LED subunit comprising a semiconductor layer of a first type and a semiconductor layer of a second type; a second LED subunit disposed on the first LED subunit and including a first type of semiconductor layer and a second type of semiconductor layer; a third LED sub-unit disposed on the second LED sub-unit and including a first type semiconductor layer and a second type semiconductor layer, wherein the second LED sub-unit and the third LED sub-unit of the first sub-pixel are electrically floating, the first LED sub-unit and the third LED sub-unit of the second sub-pixel are electrically floating, and the first LED sub-unit and the second LED sub-unit of the third sub-pixel are electrically floating.)

1. A light emitting diode pixel for a display, the light emitting diode pixel comprising:

a first subpixel, a second subpixel, and a third subpixel, each of the first subpixel, the second subpixel, and the third subpixel comprising:

a first LED sub-unit comprising a first type of semiconductor layer and a second type of semiconductor layer;

a second LED sub-unit disposed on the first LED sub-unit and including a first type of semiconductor layer and a second type of semiconductor layer; and

a third LED subunit disposed on the second LED subunit and comprising a semiconductor layer of the first type and a semiconductor layer of the second type,

wherein:

the second and third LED sub-units of the first sub-pixel are electrically floating;

the first LED sub-unit and the third LED sub-unit of the second sub-pixel are electrically floating; and is

The first LED sub-unit and the second LED sub-unit of the third sub-pixel are electrically floating.

2. A light emitting diode pixel according to claim 1, wherein:

the first LED sub-unit of the first sub-pixel, the first LED sub-unit of the second sub-pixel, and the first LED sub-unit of the third sub-pixel are isolated from each other;

the second LED sub-unit of the first sub-pixel, the second LED sub-unit of the second sub-pixel, and the second LED sub-unit of the third sub-pixel are isolated from each other;

the third LED sub-unit of the first sub-pixel, the third LED sub-unit of the second sub-pixel, and the third LED sub-unit of the third sub-pixel are isolated from each other;

each of the first LED sub-unit of the first sub-pixel, the second LED sub-unit of the second sub-pixel, and the third LED sub-unit of the third sub-pixel is configured to emit light;

light generated from the first LED subunit of the first subpixel is configured to be emitted outside of the light emitting diode pixel through the second LED subunit and the third LED subunit of the first subpixel; and is

Light generated from the second LED subunit of the second subpixel is configured to be emitted outside of the light emitting diode pixel by the third LED subunit of the second subpixel.

3. The light emitting diode pixel of claim 1, wherein the first LED subunit of the first subpixel, the second LED subunit of the second subpixel, and the third LED subunit of the third subpixel comprise a first LED stack, a second LED stack, and a third LED stack configured to emit red, green, and blue light, respectively.

4. A light emitting diode pixel according to claim 1, wherein:

the first subpixel further comprises a first upper ohmic electrode forming an ohmic contact with the first type of semiconductor layer of the first LED subunit and a first lower ohmic electrode forming an ohmic contact with the second type of semiconductor layer of the first LED subunit;

the second sub-pixel further includes a second upper ohmic electrode forming an ohmic contact with the first type of semiconductor layer of the second LED sub-unit and a second lower ohmic electrode forming an ohmic contact with the second type of semiconductor layer of the second LED sub-unit; and is

The third subpixel further includes a third upper ohmic electrode forming an ohmic contact with the first type of semiconductor layer of the third LED subunit and a third lower ohmic electrode forming an ohmic contact with the second type of semiconductor layer of the third LED subunit.

5. The light emitting diode pixel of claim 4, wherein:

the first upper ohmic electrode is electrically isolated from the first LED sub-unit of the second sub-pixel and the first LED sub-unit of the third sub-pixel;

the second upper ohmic electrode is electrically isolated from the second LED sub-unit of the first sub-pixel and the second LED sub-unit of the third sub-pixel; and is

The third upper ohmic electrode is electrically isolated from the third LED sub-unit of the first sub-pixel and the third LED sub-unit of the second sub-pixel.

6. The light emitting diode pixel of claim 4, wherein:

the first lower ohmic electrode includes a reflective layer configured to reflect light generated from the first LED subunit of the first subpixel; and is

Each of the second and third lower ohmic electrodes is transparent.

7. The light emitting diode pixel of claim 6, wherein the first lower ohmic electrode forms ohmic contacts with the first LED subunit of the first subpixel, the first LED subunit of the second subpixel, and the first LED subunit of the third subpixel.

8. The light emitting diode pixel of claim 4, wherein each of the first, second, and third subpixels further comprises:

a first color filter interposed between the first and second LED sub-units to transmit light generated from the first LED sub-unit of the first sub-pixel and reflect light generated from the second LED sub-unit of the second sub-pixel; and

a second color filter interposed between the second LED sub-unit and the third LED sub-unit to transmit light generated from the first LED sub-unit of the first sub-pixel and light generated from the second LED sub-unit of the second sub-pixel and reflect light generated from the third LED sub-unit of the third sub-pixel.

9. The light emitting diode pixel of claim 8, wherein each of the first and second color filters comprises at least one of a low pass filter, a band pass filter, and a band stop filter.

10. The light emitting diode pixel of claim 1, further comprising a support substrate,

wherein:

each of the first sub-pixel, the second sub-pixel, and the third sub-pixel further includes:

a first bonding layer interposed between the support substrate and the first LED subunit;

a second bonding layer interposed between the first LED subunit and the second LED subunit; and

a third bonding layer interposed between the second LED subunit and the third LED subunit;

the second bonding layer is transparent to light generated from the first LED subunit of the first subpixel; and is

The third bonding layer is transparent to light generated from the first LED sub-unit of the first sub-pixel and light generated from the second LED sub-unit of the second sub-pixel.

11. The light emitting diode pixel of claim 1, further comprising a light blocking layer surrounding the first, second, and third subpixels.

12. The light emitting diode pixel of claim 11, wherein the light blocking layer comprises at least one of a light reflective white material and a light absorbing black material.

13. The light emitting diode pixel of claim 1, wherein the first LED subunit of the first subpixel, the second LED subunit of the second subpixel, and the third LED subunit of the third subpixel have different areas from one another.

14. A light emitting diode pixel according to claim 1, wherein:

the first subpixel, the second subpixel, and the third subpixel comprise micro-LEDs having a surface area of less than about 10,000 square microns;

the first LED subunit is configured to emit any one of red light, green light, and blue light;

the second LED subunit is configured to emit a different one of red, green, and blue light than the first LED subunit; and is

The third LED sub-unit is configured to emit one of red, green, and blue light that is different from the first and second LED sub-units.

15. The light emitting diode pixel of claim 1, wherein at least one of the first type of semiconductor layer and the second type of semiconductor layer of an electrically floating LED subunit is not connected to any ohmic electrode.

16. A display device, the display device comprising:

a plurality of pixels disposed on a support substrate, at least one of the pixels including a light emitting diode pixel, the light emitting diode pixel including:

a first subpixel, a second subpixel, and a third subpixel, each of the first subpixel, the second subpixel, and the third subpixel comprising:

a first LED sub-unit comprising a first type of semiconductor layer and a second type of semiconductor layer;

a second LED sub-unit disposed on the first LED sub-unit and including a first type of semiconductor layer and a second type of semiconductor layer; and

a third LED subunit disposed on the second LED subunit and comprising a semiconductor layer of the first type and a semiconductor layer of the second type,

wherein:

the second and third LED sub-units of the first sub-pixel are electrically floating;

the first LED sub-unit and the third LED sub-unit of the second sub-pixel are electrically floating; and is

The first LED sub-unit and the second LED sub-unit of the third sub-pixel are electrically floating.

17. The display device of claim 16, wherein:

the second type semiconductor layer of the first LED sub-unit of the first sub-pixel, the second type semiconductor layer of the second LED sub-unit of the second sub-pixel, and the second type semiconductor layer of the third LED sub-unit of the third sub-pixel are electrically connected to a common line; and is

The first type semiconductor layer of the first LED sub-unit of the first sub-pixel, the first type semiconductor layer of the second LED sub-unit of the second sub-pixel, and the first type semiconductor layer of the third LED sub-unit of the third sub-pixel are electrically connected to different lines.

18. The display device of claim 17, wherein:

a first lower ohmic electrode commonly disposed under the first, second, and third sub-pixels; and is

The second type semiconductor layer of the second LED sub-unit of the second sub-pixel and the second type semiconductor layer of the third LED sub-unit of the third sub-pixel are electrically connected to the first lower ohmic electrode.

19. The display device of claim 18, wherein the first lower ohmic electrode comprises a reflective electrode.

20. The display device according to claim 19, wherein the reflective electrode is continuously disposed over the plurality of pixels and includes the common line.

21. The display device of claim 16, wherein each of the first, second, and third upper ohmic electrodes comprises a pad and a protrusion.

22. The display device according to claim 16, wherein in each pixel, the first LED sub-unit of the first sub-pixel, the second LED sub-unit of the second sub-pixel, and the third LED sub-unit of the third sub-pixel have different areas from each other.

Technical Field

Exemplary embodiments of the present invention relate to a light emitting diode pixel and a display device including the same, and more particularly, to a micro light emitting diode pixel having a stacked structure and a display device having the same.

Background

As inorganic light sources, light emitting diodes have been used in various technical fields such as displays, vehicle lamps, and general illumination. Along with the advantages of long lifetime, low power consumption and high response speed, light emitting diodes have rapidly replaced existing light sources.

Light emitting diodes have been mainly used as backlight light sources in display devices. However, recently, a micro LED display has been developed as a next generation display capable of realizing an image directly using a light emitting diode.

Generally, a display device implements various colors by using a mixed color of blue, green, and red light. The display device includes pixels each having sub-pixels corresponding to blue, green, and red, the color of a specific pixel may be determined based on the color of the sub-pixel therein, and an image may be displayed by a combination of the pixels.

In the micro LED display, micro LEDs corresponding to each sub-pixel are arranged on a two-dimensional plane. Therefore, a large number of micro LEDs need to be provided on one substrate. However, the micro LED has a very small size with a surface area of about 10,000 square micrometers or less, and thus, there are various problems due to such a small size. In particular, it is difficult to mount the micro LEDs on the display panel due to their small size, especially when over thousands or millions of micro LEDs are required.

The above information disclosed in this background section is only for background understanding of the inventive concept and, therefore, may contain information that does not constitute prior art.

Disclosure of Invention

Technical problem

The light emitting stack structure constructed according to the principles and some example embodiments of the present invention can be simultaneously manufactured, and thus, a step of individually mounting each light emitting diode corresponding to a sub-pixel on a display panel can be avoided.

Light emitting diodes and displays using the same (e.g., micro LEDs) constructed according to the principles and some example embodiments of the present invention can be fabricated at the wafer level by wafer bonding.

Additional features of the inventive concept will be set forth in the description which follows, and in part will be apparent from the description, or may be learned by practice of the inventive concept.

Solution to the problem

A light emitting diode pixel for a display according to an exemplary embodiment includes a first sub-pixel, a second sub-pixel, and a third sub-pixel, each of the first sub-pixel, the second sub-pixel, and the third sub-pixel including: a first LED subunit comprising a semiconductor layer of a first type and a semiconductor layer of a second type; a second LED subunit disposed on the first LED subunit and including a first type of semiconductor layer and a second type of semiconductor layer; and a third LED sub-unit disposed on the second LED sub-unit and including a first type of semiconductor layer and a second type of semiconductor layer, wherein the second LED sub-unit and the third LED sub-unit of the first sub-pixel are electrically floating, the first LED sub-unit and the third LED sub-unit of the second sub-pixel are electrically floating, and the first LED sub-unit and the second LED sub-unit of the third sub-pixel are electrically floating.

The first LED sub-unit of the first sub-pixel, the first LED sub-unit of the second sub-pixel, and the first LED sub-unit of the third sub-pixel may be isolated from each other, the second LED sub-unit of the first sub-pixel, the second LED sub-unit of the second sub-pixel, and the second LED sub-unit of the third sub-pixel may be isolated from each other, and each of the third LED sub-unit of the first sub-pixel, the third LED sub-unit of the second sub-pixel, and the third LED sub-unit of the third sub-pixel may be configured to emit light, light generated from the first LED sub-unit of the first sub-pixel may be configured to pass through the second LED sub-unit of the first sub-pixel and the third LED sub-unit of the third sub-pixel The LED sub-unit emits to the outside of the light emitting diode pixel, and light generated from the second LED sub-unit of the second sub-pixel may be configured to be emitted to the outside of the light emitting diode pixel through a third LED sub-unit of the second sub-pixel.

The first LED sub-unit of the first sub-pixel, the second LED sub-unit of the second sub-pixel, and the third LED sub-unit of the third sub-pixel may include a first LED stack, a second LED stack, and a third LED stack configured to emit red light, green light, and blue light, respectively.

The first subpixel may further include a first upper ohmic electrode forming an ohmic contact with the first type of semiconductor layer of the first LED subunit and a first lower ohmic electrode forming an ohmic contact with the second type of semiconductor layer of the first LED subunit, the second subpixel may further include a second upper ohmic electrode forming an ohmic contact with the first type of semiconductor layer of the second LED subunit and a second lower ohmic electrode forming an ohmic contact with the second type of semiconductor layer of the second LED subunit, and the third subpixel may further include a third upper ohmic electrode forming an ohmic contact with the first type of semiconductor layer of the third LED subunit and a third lower ohmic electrode forming an ohmic contact with the second type of semiconductor layer of the third LED subunit.

The first upper ohmic electrode may be electrically isolated from the first LED sub-unit of the second sub-pixel and the first LED sub-unit of the third sub-pixel, the second upper ohmic electrode may be electrically isolated from the second LED sub-unit of the first sub-pixel and the second LED sub-unit of the third sub-pixel, and the third upper ohmic electrode may be electrically isolated from the third LED sub-unit of the first sub-pixel and the third LED sub-unit of the second sub-pixel.

The first lower ohmic electrode may include a reflective layer configured to reflect light generated from the first LED sub-unit of the first sub-pixel, and each of the second and third lower ohmic electrodes may be transparent.

The first lower ohmic electrode may form ohmic contacts with the first LED sub-unit of the first sub-pixel, the first LED sub-unit of the second sub-pixel, and the first LED sub-unit of the third sub-pixel.

Each of the first sub-pixel, the second sub-pixel, and the third sub-pixel may further include: a first color filter interposed between the first and second LED sub-units to transmit light generated from the first LED sub-unit of the first sub-pixel and reflect light generated from the second LED sub-unit of the second sub-pixel; and a second color filter interposed between the second and third LED sub-units to transmit light generated from the first LED sub-unit of the first sub-pixel and light generated from the second LED sub-unit of the second sub-pixel and reflect light generated from the third LED sub-unit of the third sub-pixel.

Each of the first color filter and the second color filter may include at least one of a low pass filter, a band pass filter, and a band stop filter.

The light emitting diode pixel may further include a support substrate, wherein each of the first, second, and third sub-pixels may further include: a first bonding layer interposed between the support substrate and the first LED subunit; a second bonding layer between the first LED subunit and the second LED subunit; and a third bonding layer interposed between the second LED subunit and the third LED subunit, the second bonding layer may be transparent to light generated from the first LED subunit of the first subpixel, and the third bonding layer may be transparent to light generated from the first LED subunit of the first subpixel and light generated from the second LED subunit of the second subpixel.

The light emitting diode pixel may further include a light blocking layer surrounding the first sub-pixel, the second sub-pixel, and the third sub-pixel.

The light blocking layer may include at least one of a light reflective white material and a light absorptive black material.

The first LED sub-unit of the first sub-pixel, the second LED sub-unit of the second sub-pixel, and the third LED sub-unit of the third sub-pixel may have areas different from each other.

The first, second, and third sub-pixels may include micro-LEDs having a surface area of less than about 10,000 square microns, the first LED sub-unit may be configured to emit any one of red, green, and blue light, the second LED sub-unit may be configured to emit a different one of red, green, and blue light than the first LED sub-unit, and the third LED sub-unit may be configured to emit a different one of red, green, and blue light than the first and second LED sub-units.

At least one of the first type of semiconductor layer and the second type of semiconductor layer of the electrically floating LED subcell may not be connected to any ohmic electrode.

A display apparatus according to an exemplary embodiment includes a plurality of pixels disposed on a support substrate, at least one of the pixels may include a light emitting diode pixel for a display, the light emitting diode pixel including: a first subpixel, a second subpixel, and a third subpixel, each of the first subpixel, the second subpixel, and the third subpixel comprising: a first LED subunit comprising a semiconductor layer of a first type and a semiconductor layer of a second type; a second LED subunit disposed on the first LED subunit and including a first type of semiconductor layer and a second type of semiconductor layer; and a third LED sub-unit disposed on the second LED sub-unit and including a first type of semiconductor layer and a second type of semiconductor layer, wherein the second LED sub-unit and the third LED sub-unit of the first sub-pixel are electrically floating, the first LED sub-unit and the third LED sub-unit of the second sub-pixel are electrically floating, and the first LED sub-unit and the second LED sub-unit of the third sub-pixel are electrically floating.

The second type semiconductor layer of the first LED sub-unit of the first sub-pixel, the second type semiconductor layer of the second LED sub-unit of the second sub-pixel, and the second type semiconductor layer of the third LED sub-unit of the third sub-pixel may be electrically connected to a common line, and the first type semiconductor layer of the first LED sub-unit of the first sub-pixel, the first type semiconductor layer of the second LED sub-unit of the second sub-pixel, and the first type semiconductor layer of the third LED sub-unit of the third sub-pixel may be electrically connected to different lines.

A first lower ohmic electrode may be commonly disposed under the first, second, and third sub-pixels, and the second type semiconductor layer of the second LED sub-unit of the second sub-pixel and the second type semiconductor layer of the third LED sub-unit of the third sub-pixel may be electrically connected to the first lower ohmic electrode.

The first lower ohmic electrode may include a reflective electrode.

The reflective electrode may be continuously disposed over the plurality of pixels and may include the common line.

Each of the first, second, and third upper ohmic electrodes may include a pad and a protrusion.

In each pixel, the first LED sub-unit of the first sub-pixel, the second LED sub-unit of the second sub-pixel, and the third LED sub-unit of the third sub-pixel may have areas different from each other.

A light emitting diode pixel for a display according to an exemplary embodiment includes: supporting a substrate; a first sub-pixel, a second sub-pixel, and a third sub-pixel, each of the first sub-pixel, the second sub-pixel, and the third sub-pixel being disposed on the support substrate and being spaced apart from each other in a horizontal direction, each of the first sub-pixel, the second sub-pixel, and the third sub-pixel being configured to emit light having a first wavelength, light having a second wavelength, and light having a third wavelength, respectively, and including: a first LED subunit comprising a semiconductor layer of a first type and a semiconductor layer of a second type; a second LED subunit disposed on the first LED subunit and including a first type of semiconductor layer and a second type of semiconductor layer; and a third LED subunit disposed on the second LED subunit and including a first type of semiconductor layer and a second type of semiconductor layer, wherein the first subpixel is configured to emit light from its first LED subunit, the second subpixel is configured to emit light from its second LED subunit, and the third subpixel is configured to emit light from its third LED subunit.

A light emitting diode pixel for a display according to an exemplary embodiment includes: a first subpixel comprising a first LED subunit; a second subpixel comprising a second LED subunit; and a third sub-pixel including a third LED sub-unit, wherein each of the first, second, and third LED sub-units includes a first type semiconductor layer and a second type semiconductor layer, and the first, second, and third LED sub-units are spaced apart from each other in a first direction, are disposed at different planes from each other, and do not overlap each other in the first direction.

The first, second and third LED subunits may include first, second and third LED stacks configured to emit light having wavelengths different from each other, respectively.

The second and third sub-pixels may further include at least one bonding layer disposed under the second and third LED sub-units, respectively.

The number of bonding layers disposed under the second LED subunit may be greater than the number of bonding layers disposed under the third LED subunit.

The first and second sub-pixels may further include at least one bonding layer disposed at upper sides of the first and second LED sub-units, respectively.

At least two bonding layers may be disposed in an upper region of the first LED subunit.

The first subpixel may further include a first lower ohmic electrode having a reflective layer and disposed under the first LED subunit to form an ohmic contact with the second type semiconductor layer of the first LED subunit.

The reflective layer may extend to overlap the second LED sub-unit and the third LED sub-unit.

The second type semiconductor layer of the second LED sub-unit and the second type semiconductor layer of the third LED sub-unit may be electrically connected to the first lower ohmic electrode in common.

The first subpixel may further include a first upper ohmic electrode forming an ohmic contact with the first type of semiconductor layer of the first LED subunit, the second subpixel may further include a second upper ohmic electrode forming an ohmic contact with the first type of semiconductor layer of the second LED subunit and a second lower ohmic electrode forming an ohmic contact with the second type of semiconductor layer of the second LED subunit, the third subpixel may further include a third upper ohmic electrode forming an ohmic contact with the first type of semiconductor layer of the third LED subunit and a third lower ohmic electrode forming an ohmic contact with the second type of semiconductor layer of the third LED subunit, and the second lower ohmic electrode and the third lower ohmic electrode may be electrically connected to the first lower ohmic electrode.

Each of the second and third lower ohmic electrodes may be transparent.

The light emitting diode pixel may further include a support substrate on which the first, second, and third sub-pixels are disposed, and a bonding layer interposed between the reflective layer and the support substrate.

The light emitting diode pixel may further include a light blocking layer surrounding a side surface of the first sub-pixel, a side surface of the second sub-pixel, and a side surface of the third sub-pixel.

The light blocking layer may include at least one of a light reflective white material and a light absorptive black material.

The first, second and third LED subunits may have different areas from each other.

A display device may include a plurality of pixels disposed on a support substrate, and at least one of the pixels may include a light emitting diode pixel according to an exemplary embodiment.

The second type semiconductor layer of the first LED sub-unit, the second type semiconductor layer of the second LED sub-unit, and the second type semiconductor layer of the third LED sub-unit may be electrically connected to a common line, and the first type semiconductor layer of the first LED sub-unit, the first type semiconductor layer of the second LED sub-unit, and the first type semiconductor layer of the third LED sub-unit may be electrically connected to different lines.

The first subpixel may further include a first upper ohmic electrode forming an ohmic contact with the first type of semiconductor layer of the first LED subunit and a first lower ohmic electrode forming an ohmic contact with the second type of semiconductor layer of the first LED subunit, the second subpixel may further include a second upper ohmic electrode forming an ohmic contact with the first type of semiconductor layer of the second LED subunit and a second lower ohmic electrode forming an ohmic contact with the second type of semiconductor layer of the second LED subunit, and the third sub-pixel may further include a third upper ohmic electrode forming an ohmic contact with the first type of semiconductor layer of the third LED sub-unit and a third lower ohmic electrode forming an ohmic contact with the second type of semiconductor layer of the third LED sub-unit.

The first lower ohmic electrode may be commonly disposed under the first, second, and third sub-pixels, and the second type semiconductor layer of the second LED sub-unit and the second type semiconductor layer of the third LED sub-unit may be electrically connected to the first lower ohmic electrode.

The first lower ohmic electrode may include a reflective electrode.

The reflective electrode may be continuously disposed over the plurality of pixels, and may include a common line.

Each of the first, second, and third upper ohmic electrodes may include a pad and a protrusion.

In each pixel, the first, second, and third LED subunits may have areas different from each other.

A light emitting diode pixel for a display according to an exemplary embodiment includes: a first subpixel comprising a first LED subunit; a second sub-pixel including a first LED sub-unit and a second LED sub-unit disposed thereon; and a third sub-pixel including a first LED sub-unit, a second LED sub-unit, and a third LED sub-unit sequentially disposed thereon, wherein each of the first LED sub-unit, the second LED sub-unit, and the third LED sub-unit includes a first type semiconductor layer and a second type semiconductor layer, the second LED sub-unit of the second sub-pixel is isolated from the second LED sub-unit of the third sub-pixel, and the first LED sub-unit of the first sub-pixel is isolated from the first LED sub-unit of the second sub-pixel and the first LED sub-unit of the third sub-pixel.

The first LED sub-unit of the second sub-pixel, the first LED sub-unit of the third sub-pixel, and the second LED sub-unit of the third sub-pixel may be electrically floating.

The first LED sub-unit of the first sub-pixel, the second LED sub-unit of the second sub-pixel, and the third LED sub-unit of the third sub-pixel may be configured to emit light having different wavelengths.

Light generated from the first LED subunit of the first subpixel may be configured to be emitted to the outside of the light emitting diode pixel without passing through a second LED subunit, and light generated from the second LED subunit of the second subpixel may be configured to be emitted to the outside of the light emitting diode pixel without passing through the third LED subunit.

The light emitting diode pixel may further include an insulating layer covering the first, second, and third sub-pixels, the insulating layer abutting an upper surface of the first LED sub-unit of the first sub-pixel, an upper surface of the second LED sub-unit of the second sub-pixel, and an upper surface of the third LED sub-unit of the third sub-pixel.

The second sub-pixel may further include a first reflective layer interposed between the first LED sub-unit and the second LED sub-unit, and the third sub-pixel may further include a second reflective layer interposed between the first LED sub-unit and the second LED sub-unit and a third reflective layer interposed between the second LED sub-unit and the third LED sub-unit.

The second subpixel may further include a first bonding layer between the first reflective layer and the first LED subunit, and the third subpixel may further include a second bonding layer between the second reflective layer and the first LED subunit and a third bonding layer between the third reflective layer and the second LED subunit.

Each of the first bonding layer, the second bonding layer, and the third bonding layer may include a metal.

The second subpixel may further include an insulating layer insulating the first LED subunit from the first bonding layer, and the third subpixel may further include insulating layers insulating the first LED subunit and the second LED subunit from the second bonding layer and the third bonding layer, respectively.

The first subpixel may further include a first upper ohmic electrode contacting the first type of semiconductor layer of the first LED subunit and a first lower ohmic electrode contacting the second type of semiconductor layer of the first LED subunit, the second subpixel may further include a second upper ohmic electrode contacting the first type of semiconductor layer of the second LED subunit and a second lower ohmic electrode contacting the second type of semiconductor layer of the second LED subunit, and the third subpixel may further include a third upper ohmic electrode contacting the first type of semiconductor layer of the third LED subunit and a third lower ohmic electrode contacting the second type of semiconductor layer of the third LED subunit.

The first lower ohmic electrode may include a reflective layer commonly disposed under the first, second, and third sub-pixels, and the first, second, and third lower ohmic electrodes may be electrically connected to a common line.

At least one of the LED sub-unit in the second sub-pixel and the LED sub-unit in the third sub-pixel may not be configured to emit light.

The first LED sub-unit of the first sub-pixel, the second LED sub-unit of the second sub-pixel, and the third LED sub-unit of the third sub-pixel may have areas different from each other.

The light emitting diode pixel may further include a light blocking layer surrounding a side surface of the first LED subunit, a side surface of the second LED subunit, and a side surface of the third LED subunit.

Only one of the first LED sub-unit of the first sub-pixel, the first LED sub-unit of the second sub-pixel, and the first LED sub-unit of the third sub-pixel may be configured to emit light.

The light may be configured to be emitted from substantially different planes in the first sub-pixel, the second sub-pixel, and the third sub-pixel.

A display device may include a support substrate and a plurality of pixels disposed on the support substrate, at least one of the pixels may include a light emitting diode pixel according to an exemplary embodiment.

The second type semiconductor layer of the first LED sub-unit of the first sub-pixel, the second type semiconductor layer of the second LED sub-unit of the second sub-pixel, and the second type semiconductor layer of the third LED sub-unit of the third sub-pixel may be electrically connected to a common line, and the first type semiconductor layer of the first LED sub-unit of the first sub-pixel, the first type semiconductor layer of the second LED sub-unit of the second sub-pixel, and the first type semiconductor layer of the third LED sub-unit of the third sub-pixel may be electrically connected to different lines from each other.

The light emitting diode pixel may further include a first lower ohmic electrode forming an ohmic contact with the second type semiconductor layer of the first subpixel, wherein the first lower ohmic electrode may include a reflective layer disposed between the first LED subunit and the support substrate.

The first lower ohmic electrode may be continuously disposed over the plurality of pixels.

The first LED sub-unit of the first sub-pixel, the second LED sub-unit of the second sub-pixel, and the third LED sub-unit of the third sub-pixel may have different areas.

The light emitting diode pixel may further include a light blocking layer covering a side surface of the first LED subunit, a side surface of the second LED subunit, and a side surface of the third LED subunit.

It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are intended to provide further explanation of the invention as claimed.

Advantageous effects of the invention

The light emitting stack structure constructed according to the principles and some example embodiments of the present invention can be simultaneously manufactured, and thus, a step of individually mounting each light emitting diode corresponding to a sub-pixel on a display panel can be avoided.

Light emitting diodes and displays using the same (e.g., micro LEDs) constructed according to the principles and some example embodiments of the present invention can be fabricated at the wafer level by wafer bonding.

Drawings

The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate exemplary embodiments of the invention and together with the description serve to explain the inventive concept.

Fig. 1 is a schematic plan view of a display apparatus according to an exemplary embodiment.

Fig. 2 is a schematic cross-sectional view of a light emitting diode pixel for a display according to an exemplary embodiment.

Fig. 3 is a schematic circuit diagram of a display apparatus according to an exemplary embodiment.

Fig. 4 is a schematic plan view of a display apparatus according to an exemplary embodiment.

Fig. 5 is an enlarged plan view of one pixel of the display device of fig. 4.

Fig. 6A is a schematic cross-sectional view taken along line a-a of fig. 5.

Fig. 6B is a schematic sectional view taken along line B-B of fig. 5.

Fig. 6C is a schematic sectional view taken along line C-C of fig. 5.

Fig. 6D is a schematic cross-sectional view taken along line D-D of fig. 5.

Fig. 7A, 7B, 7C, 8A, 8B, 9A, 9B, 10A, 10B, 11A, 11B, 12A, 12B, 13A, 13B, 14A, 14B, 15A, 15B, 16A, 16B, 17A, 17B, 18, 19A, and 19B are schematic plan and sectional views illustrating a method of manufacturing a display device according to an exemplary embodiment.

Fig. 20 is a schematic cross-sectional view of a display apparatus according to another exemplary embodiment.

Fig. 21 is a schematic plan view of a display apparatus according to an exemplary embodiment.

FIG. 22 is a schematic cross-sectional view of a light emitting diode pixel for a display according to an example embodiment.

Fig. 23 is a schematic circuit diagram of a display device according to an exemplary embodiment.

Fig. 24 is a schematic plan view of a display apparatus according to an exemplary embodiment.

Fig. 25 is an enlarged plan view of one pixel of the display device of fig. 24.

Fig. 26A is a schematic sectional view taken along line a-a of fig. 25.

Fig. 26B is a schematic sectional view taken along line B-B of fig. 25.

Fig. 26C is a schematic sectional view taken along line C-C of fig. 25.

Fig. 26D is a schematic sectional view taken along line D-D of fig. 25.

Fig. 27A, 27B, 27C, 28A, 28B, 29A, 29B, 30A, 30B, 31A, 31B, 32A, 32B, 33A, 33B, 34A, 34B, 35A, 35B, 36A, 36B, 37A, 37B, 38, 39A, and 39B are schematic plan and sectional views illustrating a method of manufacturing a display device according to an exemplary embodiment.

Fig. 40 is a schematic cross-sectional view of a display apparatus according to another exemplary embodiment.

Fig. 41 is a schematic plan view of a display apparatus according to an exemplary embodiment.

FIG. 42 is a schematic cross-sectional view of a light emitting diode pixel for a display according to an example embodiment.

Fig. 43 is a schematic circuit diagram of a display device according to an exemplary embodiment.

Fig. 44 is a schematic plan view of a display apparatus according to an exemplary embodiment.

Fig. 45 is an enlarged plan view of one pixel of the display device of fig. 44.

Fig. 46A is a schematic sectional view taken along line a-a of fig. 45.

Fig. 46B is a schematic sectional view taken along line B-B of fig. 45.

Fig. 46C is a schematic sectional view taken along line C-C of fig. 45.

Fig. 46D is a schematic sectional view taken along line D-D of fig. 45.

Fig. 47A, 47B, 47C, 48A, 48B, 49A, 49B, 50A, 50B, 51A, 51B, 52A, 52B, 53A, 53B, 54A, 54B, 55A, 55B, 56A, 56B, 57, 58A, 58B, and 59 are schematic plan and sectional views illustrating a method of manufacturing a display device according to an exemplary embodiment.

Fig. 60 is a schematic cross-sectional view of a display apparatus according to another exemplary embodiment.

Detailed Description

In the following description, for purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of various exemplary embodiments or implementations of the present invention. As used herein, "examples" and "embodiments" are interchangeable words, which are non-limiting examples of apparatus or methods that employ one or more of the inventive concepts disclosed herein. It may be evident, however, that the various exemplary embodiments may be practiced without these specific details or with one or more equivalent arrangements. In other instances, well-known structures and devices are shown in block diagram form in order to avoid unnecessarily obscuring the various exemplary embodiments. Moreover, the various exemplary embodiments may be different, but are not necessarily exclusive. For example, particular shapes, configurations and characteristics of an exemplary embodiment may be used or implemented in another exemplary embodiment without departing from the inventive concept.

Unless otherwise indicated, the illustrated exemplary embodiments are to be understood as providing exemplary features of varying detail of some ways in which the inventive concepts may be practiced. Thus, unless otherwise specified, features, components, modules, layers, films, panels, regions, and/or aspects and the like (individually or collectively, "elements" hereinafter) of the various embodiments may be otherwise combined, separated, interchanged, and/or rearranged without departing from the inventive concepts.

The use of cross-hatching and/or shading in the drawings is typically provided to clarify the boundaries between adjacent elements. As such, unless otherwise specified, the presence or absence of cross-hatching or shading does not convey or indicate any preference or requirement for a particular material, material property, size, proportion of an element, commonality between illustrated elements, and/or any other characteristic, attribute, property, etc. Further, in the drawings, the size and relative sizes of elements may be exaggerated for clarity and/or descriptive purposes. While example embodiments may be implemented differently, the particular process sequence may be performed differently than described. For example, two processes described in succession may be executed substantially concurrently or in the reverse order to that described. In addition, like reference numerals denote like elements.

When an element such as a layer is referred to as being "on," "connected to" or "coupled to" another element or layer, it can be directly on, connected or coupled to the other element or layer or intervening elements or layers may be present. However, when an element or layer is referred to as being "directly on," "directly connected to" or "directly coupled to" another element or layer, there are no intervening elements or layers present. For purposes of this specification, the term "connected" may refer to physical, electrical, and/or fluid connections, with or without intervening elements. Further, the D1 axis, D2 axis, and D3 axis are not limited to three axes of a rectangular coordinate system, such as the x axis, y axis, and z axis, and may be interpreted in a broader sense. For example, the D1, D2, and D3 axes may be perpendicular to each other, or may represent different directions that are not perpendicular to each other. For purposes of this disclosure, "at least one of X, Y and Z" and "at least one selected from the group consisting of X, Y and Z" can be interpreted as X only, Y only, Z only, or any combination of two or more of X, Y and Z, such as XYZ, XYY, YZ, and ZZ, for example. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.

Although the terms first, second, etc. may be used herein to describe various types of elements, these elements should not be limited by these terms. These terms are used to distinguish one element from another. Thus, a first element discussed below could be termed a second element without departing from the teachings of the present disclosure.

Spatially relative terms such as "below … …," "below … …," "below … …," "below," "above … …," "above … …," "higher" and "side" (e.g., as in "side walls") may be used herein for descriptive purposes to describe one element's relationship to another element as illustrated in the figures. Spatially relative terms are intended to cover different orientations of the device in use, operation, and/or manufacture in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, elements described as "below" or "beneath" other elements or features would then be oriented "above" the other elements or features. Thus, the exemplary term "below … …" can encompass both an orientation of "above … …" and "below … …". Further, the devices may be otherwise oriented (e.g., rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly.

The terminology used herein is for the purpose of describing particular embodiments and is not intended to be limiting. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. Furthermore, the terms "comprises," "comprising," "includes," "including," "has," "having" and/or "including," when used in this specification, specify the presence of stated features, integers, steps, operations, elements, components, and/or groups thereof, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. It is also noted that, as used herein, the terms "substantially," "about," and other similar terms are used as approximate terms and not as terms of degree, and as such, are used to interpret the inherent variation of measured, calculated, and/or provided values that would be recognized by one of ordinary skill in the art.

Various exemplary embodiments are described herein with reference to cross-sectional and/or exploded views as illustrations of idealized exemplary embodiments and/or intermediate structures. In this way, variations from the shapes of the illustrations as a result, for example, of manufacturing techniques and/or tolerances, are to be expected. Therefore, the exemplary embodiments disclosed herein should not necessarily be construed as being limited to the shapes of the regions specifically illustrated, but should include deviations in shapes that result, for example, from manufacturing. In this manner, the regions illustrated in the figures may be schematic in nature and the shapes of the regions may not reflect the actual shape of a region of a device and, thus, are not necessarily intended to be limiting.

Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure is a part. Unless explicitly defined as such herein, terms such as those defined in commonly used dictionaries should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and will not be interpreted in an idealized or overly formal sense.

Hereinafter, exemplary embodiments will be described in detail with reference to the accompanying drawings. As used herein, a light emitting diode pixel or light emitting diode according to an exemplary embodiment may comprise a micro LED having a surface area of less than about 10,000 square microns as is known in the art. In other exemplary embodiments, the surface area of the micro-LEDs may be less than about 4,000 square microns, or less than about 2,500 square microns, depending on the particular application.

Fig. 1 is a schematic plan view of a display device according to an exemplary embodiment, and fig. 2 is a schematic cross-sectional view of a light emitting diode pixel for a display according to an exemplary embodiment.

Referring to fig. 1, the display apparatus 1000 includes a support substrate 51 and a plurality of pixels 100 disposed on the support substrate 51. Each pixel 100 includes a first sub-pixel R, a second sub-pixel G, and a third sub-pixel B.

Referring to fig. 2, the support substrate 51 supports the LED stacks 23, 33, 43. The support substrate 51 may include a circuit on a surface thereof or in the same, but is not limited thereto. The support substrate 51 may include, for example, a sapphire substrate, a glass substrate, a Si substrate, or a Ge substrate.

Each of the first, second and third sub-pixels R, G and B comprises a first LED stack 23, a second LED stack 33 and a third LED stack 43. Each of the first LED stack 23, the second LED stack 33 and the third LED stack 43 comprises an n-type semiconductor layer, a p-type semiconductor layer and an active layer interposed between the n-type semiconductor layer and the p-type semiconductor layer. The active layer may have a multiple quantum well layer structure.

According to an exemplary embodiment, the first LED stack 23 may be an inorganic light emitting diode emitting red light, the second LED stack 33 may be an inorganic light emitting diode emitting green light, and the third LED stack 43 may be an inorganic light emitting diode emitting blue light. The first LED stack 23 may include a GaInP-based well layer, and the second and third LED stacks 33 and 43 may include a GaInN-based well layer.

The first sub-pixel R is adapted to emit light from the first LED stack 23, the second sub-pixel G is adapted to emit light from the second LED stack 33, and the third sub-pixel B is adapted to emit light from the third LED stack 43. The first LED stack 23, the second LED stack 33 and the third LED stack 43 may be driven independently.

The second and third LED stacks 33 and 43 of the first subpixel R are electrically floating, the first and third LED stacks 23 and 43 of the second subpixel G are electrically floating, and the first and second LED stacks 23 and 33 of the third subpixel B are electrically floating. Since the electrically floating LED stack in each sub-pixel is insulated and isolated from a current path through which a current is supplied from the outside, the electrically floating LED stack cannot be driven. As such, the floating LED stack may be a dummy stack that planarizes the upper surface of each sub-pixel R, G, B so that they are flush with each other.

As shown in fig. 2, light generated from the first LED stack 23 of the first subpixel R is emitted to the outside through the second LED stack 33 and the third LED stack 43. In addition, light generated from the second LED stack 33 of the second subpixel G is emitted to the outside through the third LED stack 43. In addition, light generated from the third LED stack 43 of the third subpixel B may be emitted to the outside without passing through the first and second LED stacks 23 and 33. However, the inventive concept is not limited thereto. When in other exemplary embodiments the light emitting diode pixel comprises a micro LED having a surface area of less than about 10,000 square microns, or less than about 4,000 square microns, or 2,500 square microns as known in the art, the first epitaxial stack 20 may emit any one of red, green, and blue light, and the second epitaxial stack 30 and the third epitaxial stack 40 may emit a different one of red, green, and blue light, without negatively affecting operation due to the small form factor of the micro LED.

Fig. 3 is a schematic circuit diagram of a display apparatus according to an exemplary embodiment.

Referring to fig. 3, the display device according to an exemplary embodiment may be driven in a passive matrix manner. As described with reference to fig. 1 and 2, one pixel includes a first subpixel R, a second subpixel G, and a third subpixel B. The first LED stack 23 of the first subpixel R emits light having a first wavelength, the second LED stack 33 of the second subpixel G emits light having a second wavelength, and the third LED stack 43 of the third subpixel B emits light having a third wavelength. The anode electrode of the first subpixel R, the anode electrode of the second subpixel G, and the anode electrode of the third subpixel B may be connected to a common line, for example, a data line Vdata 25, and the cathode electrode of the first subpixel R, the cathode electrode of the second subpixel G, and the cathode electrode of the third subpixel B may be connected to different lines, for example, scan lines Vscan 71, 73, 75.

For example, in the first pixel, the anode of the first sub-pixel R, the anode of the second sub-pixel G, and the anode of the third sub-pixel B are commonly connected to the data line Vdata1, and the cathode of the first sub-pixel R, the cathode of the second sub-pixel G, and the cathode of the third sub-pixel B are respectively connected to the scan lines Vscan1-1, Vscan1-2, Vscan 1-3. Therefore, the sub-pixels R, G, B in the same pixel can be driven individually.

In addition, each LED stack 23, 33, 43 in each sub-pixel R, G, B may be driven by pulse width modulation or by varying the magnitude of the current to control the brightness of each sub-pixel. Alternatively, the brightness may be adjusted by adjusting the area of the first LED stack 23, the area of the second LED stack 33, and the area of the third LED stack 43. For example, the first sub-pixel R, which may emit red light having low visibility, may be formed to have a larger area than the second sub-pixel G or the third sub-pixel B.

Fig. 4 is a schematic plan view of a display apparatus according to an exemplary embodiment.

Referring to fig. 4, a display apparatus 1000A illustrated in the circuit diagram of fig. 3 according to an exemplary embodiment may include a plurality of pixels 100A disposed on a support substrate 51 (see fig. 5). Each sub-pixel R, G, B is connected to a reflective electrode 25 and to interconnect lines 71, 73, 75. As shown in fig. 3, the reflective electrode 25 may correspond to the data line Vdata, and the interconnection lines 71, 73, 75 may correspond to the scan line Vscan.

The pixels 100A may be arranged in a matrix form in which anodes of the sub-pixels R, G, B in each pixel are commonly connected to the reflective electrode 25, and cathodes of the sub-pixels R, G, B in each pixel are respectively connected to the interconnection lines 71, 73, 75 isolated from each other. The connection portions 71a, 73a, 75a may connect the interconnection lines 71, 73, 75 to the sub-pixels R, G, B.

Fig. 5 is an enlarged plan view of one pixel 100A of the display device of fig. 4. Fig. 6A, 6B, 6C and 6D are schematic sectional views taken along line a-a, line B-B, line C-C and line D-D of fig. 5, respectively.

Referring to fig. 4, 5, 6A, 6B, 6C, and 6D, the display apparatus 1000A may include a support substrate 51, a plurality of pixels 100A, a first subpixel R, a second subpixel G, a third subpixel B, a first LED stack 23, a second LED stack 33, a third LED stack 43, a reflective electrode 25 (or a first-2 ohmic electrode), a first-1 ohmic electrode 29, a second-1 ohmic electrode 39, a second-2 ohmic electrode 35, a third-1 ohmic electrode 49, a third-2 ohmic electrode 45, a first color filter 37, a second color filter 47, a hydrophilic material layer 56, 58, a first bonding layer 53, a second bonding layer 55, a third bonding layer 57, a first protective layer 61, a light blocking material 63, a second protective layer 65, a third protective layer 67, interconnection lines 71, 73, 75, and connection portions 71a, 71a, 73a, 75a, 77 b.

The support substrate 51 supports the LED stacks 23, 33, 43. The support substrate 51 may include a circuit on a surface thereof or in the same, but the inventive concept is not limited thereto. The support substrate 51 may include, for example, a glass substrate, a sapphire substrate, a Si substrate, or a Ge substrate.

The first LED stack 23 includes a first conductive type semiconductor layer 23a and a second conductive type semiconductor layer 23 b. The second LED stack 33 includes a first conductive type semiconductor layer 33a and a second conductive type semiconductor layer 33 b. The third LED stack 43 includes a first conductive type semiconductor layer 43a and a second conductive type semiconductor layer 43 b. In addition, the active layer may be interposed between the first and second conductive type semiconductor layers 23a and 23b, between the first and second conductive type semiconductor layers 33a and 33b, and between the first and second conductive type semiconductor layers 43a and 43b, respectively.

In an exemplary embodiment, each of the first conductive type semiconductor layers 23a, 33a, 43a may be an n-type semiconductor layer, and each of the second conductive type semiconductor layers 23b, 33b, 43b may be a p-type semiconductor layer. In some exemplary embodiments, a roughened surface may be formed on at least one surface of the first conductive type semiconductor layer 23a, 33a, 43a by surface texturing (texturing). However, the inventive concept is not limited thereto, and the type of the semiconductor layer in each LED stack may be changed in some exemplary embodiments.

The first LED stack 23 is arranged adjacent to the support substrate 51, the second LED stack 33 is arranged above the first LED stack 23, and the third LED stack 43 is arranged above the second LED stack. The light generated from the first LED stack 23 may be emitted to the outside through the second LED stack 33 and the third LED stack 43. In addition, light generated from the second LED stack 33 may be emitted to the outside through the third LED stack 43.

The materials forming the first, second, and third LED stacks 23, 33, and 43 may be substantially the same as those described with reference to fig. 2, and thus, a detailed description thereof will be omitted in order to avoid redundancy.

The reflective electrode 25 forms an ohmic contact with a lower surface of the first LED stack 23 (e.g., the second conductive type semiconductor layer 23 b). The reflective electrode 25 may be commonly connected to the first LED stack 23 of the first, second, and third sub-pixels R, G, and B. In addition, the reflective electrode 25 may be commonly connected to the plurality of pixels 100a as a data line Vdata.

The reflective electrode 25 may be formed of, for example, a material layer forming ohmic contact with the second conductive type semiconductor layer 23b of the first LED stack 23, and may include a reflective layer that may reflect light (e.g., red light) generated from the first LED stack 23.

The reflective electrode 25 may include an ohmic reflective layer, and may Be formed of, for example, an Au-Zn alloy or an Au-Be alloy. These alloys have high reflectance for light in the red range and form ohmic contact with the second conductive type semiconductor layer 23 b.

The first-1 ohmic electrode 29 forms an ohmic contact with the first conductive type semiconductor layer 23a of the first subpixel R. The ohmic electrode 29 may not be formed on the first conductive type semiconductor layer 23a of each of the second and third sub-pixels G and B such that the first LED stack 23 of the second and third sub-pixels G and B is electrically floating. The first-1 ohmic electrode 29 may include a pad region and an extension portion (see fig. 9A), and as shown in fig. 6B, the connection portion 75a may be connected to the pad region of the first-1 ohmic electrode 29.

The second-1 ohmic electrode 39 forms an ohmic contact with the first conductive type semiconductor layer 33a of the second LED stack 33 of the second subpixel G. The ohmic electrode 39 may not be formed on the first conductive type semiconductor layer 33a of each of the first and third sub-pixels R and B such that the second LED stack 33 of the first and third sub-pixels R and B is electrically floating.

The second-1 ohmic electrode 39 may include a pad region and an extension portion, and as shown in fig. 6C, the connection portion 73a may be connected to the pad region of the second-1 ohmic electrode 39.

The second-2 ohmic electrode 35 forms an ohmic contact with the second conductive type semiconductor layer 33B of the second LED stack 33 of each of the first, second and third sub-pixels R, G and B. The second-2 ohmic electrode 35 may be transparent to the light generated from the first LED stack 23 and may be formed of, for example, a metal layer or a conductive oxide layer.

The electrode pad 36 is formed on the second-2 ohmic electrode 35 of the second subpixel G. The electrode pad 36 may be restrictively disposed on the second-2 ohmic electrode 35 of the second subpixel G and may not be disposed on the second-2 ohmic electrode 35 of the first subpixel R or the third subpixel B. The connection portion 77b may be connected to the electrode pad 36.

The third-1 ohmic electrode 49 forms an ohmic contact with the first conductive type semiconductor layer 43a of the third LED stack 43 of the third subpixel B. The ohmic electrode 49 may not be formed on the first conductive type semiconductor layer 43a of each of the first and second sub-pixels R and G such that the third LED stack 43 of the first and second sub-pixels R and G is electrically floating.

The third-1 ohmic electrode 49 may include a pad region and an extension portion (see fig. 12A), and as shown in fig. 6D, the connection portion 71a may be connected to the pad region of the third-1 ohmic electrode 49.

The third-2 ohmic electrode 45 forms an ohmic contact with the second conductive type semiconductor layer 43B of the third LED stack 43 of each of the first, second and third sub-pixels R, G and B. The third-2 ohmic electrode 45 may be transparent to light generated from the first and second LED stacks 23 and 33, and may be formed of, for example, a metal layer or a conductive oxide layer.

The electrode pad 46 is formed on the third-2 ohmic electrode 45 of the third subpixel B. The electrode pad 46 may be restrictively disposed on the third-2 ohmic electrode 45 of the third subpixel B and may not be disposed on the third-2 ohmic electrode 45 of the first subpixel R or the second subpixel G. The connection portion 77a may be connected to the electrode pad 46.

The reflective electrode 25, the second-2 ohmic electrode 35, and the third-2 ohmic electrode 45 may assist current diffusion (currentspreading) by ohmic contact with the p-type semiconductor layer of each LED stack, and the first-1 ohmic electrode 29, the second-1 ohmic electrode 39, and the third-1 ohmic electrode 49 may assist current diffusion by ohmic contact with the n-type semiconductor layer of each LED stack.

In each subpixel R, G, B, a first color filter 35 may be interposed between the first LED stack 23 and the second LED stack 33. In addition, a second color filter 45 may be interposed between the second LED stack 33 and the third LED stack 43. The first color filter 35 transmits light generated from the first LED stack 23 while reflecting light generated from the second LED stack 33. The second color filter 45 transmits light generated from the first and second LED stacks 23 and 33 while reflecting light generated from the third LED stack 43. Accordingly, light generated from the first LED stack 23 may be emitted to the outside through the second LED stack 33 and the third LED stack 43, and light generated from the second LED stack 33 may be emitted to the outside through the third LED stack 43. In this way, light generated from the second LED stack 33 may be prevented from entering the first LED stack 23, and light generated from the third LED stack 43 may be prevented from entering the second LED stack 33, thereby preventing light loss.

In some exemplary embodiments, the first color filter 37 may reflect light generated from the third LED stack 43.

The first and second color filters 37 and 45 may be, for example, a low-pass filter allowing light in a low frequency band (e.g., in a long wavelength band) to pass therethrough, a band-pass filter allowing light in a predetermined wavelength band to pass therethrough, or a band-stop filter preventing light in the predetermined wavelength band from passing therethrough. Specifically, the first color filter 37 and the second color filter 45 may include a Distributed Bragg Reflector (DBR). The distributed bragg reflector may be formed by alternately stacking insulating layers having different refractive indices on top of each other, for example, by alternately stacking TiO₂Layer and SiO₂And (4) layer formation. In addition, the stop band of the distributed Bragg reflector can be adjusted by adjusting TiO₂Layer and SiO₂The thickness of the layer. The low-pass filter and the band-pass filter may also be formed by alternately stacking insulating layers having different refractive indexes on top of each other.

The first bonding layer 53 bonds the first LED stack 23 to the support substrate 51. As shown in the figure, the reflective electrode 25 may be adjacent to the first bonding layer 53. The first bonding layer 53 may be a light-transmitting layer or an opaque layer. The first bonding layer 53 may be formed of an organic material or an inorganic material. Examples of the organic material may include SU8, poly (methyl methacrylate) (PMMA), polyimide, parylene, benzocyclobutene (BCB), or others, and examples of the inorganic material may include Al₂O₃、SiO₂、SiN_xOr otherwise. The organic material layer may be bonded under high vacuum and high pressure conditions, and the inorganic material layer may be bonded under high vacuum after the surface energy is changed using plasma by, for example, chemical mechanical polishing to planarize the surface of the inorganic material layer. The first bonding layer 53 may also be formed of transparent spin-on glass. Specifically, a bonding layer formed of a black epoxy resin capable of absorbing light may be used as the first bonding layer 53, thereby improving the contrast of the display device.

The second bonding layer 55 bonds the second LED stack 33 to the first LED stack 23. The second bonding layer 55 may be formed of a transparent organic material or a transparent inorganic material. Examples of the organic material may include SU8, poly (methyl methacrylate) (PMMA), polyimide, parylene, benzocyclobutene (BCB), or others, and examples of the inorganic material may include Al₂O₃、SiO₂、SiN_xOr otherwise. In addition, the second bonding layer 55 may be formed of transparent spin-on glass. As shown in the figure, the second bonding layer 55 may abut the first LED stack 23. In addition, the second bonding layer 55 may adjoin the first color filter 37. Here, the hydrophilic material layer 56 may be interposed between the second bonding layer 55 and the first color filter 37.

The hydrophilic material layer 56 may change the surface property of the first color filter 37 from hydrophobicity to hydrophilicity, thereby improving the adhesive strength of the second bonding layer 55 to prevent the second bonding layer 55 from peeling off from the first color filter 37. In some exemplary embodiments, when the first color filter 37 has a hydrophilic lower surface, the hydrophilic material layer 56 may be omitted. For example, it is possible to form a first color filter 37 by depositing SiO on the surface thereof₂Or the hydrophilic material layer 56 is formed by plasma modification of the surface of the first color filter 37.

In some exemplary embodiments, a hydrophilic material layer may be formed on the surface of the first LED stack 23 to change the surface property of the first LED stack 23 from hydrophobic to hydrophilic. In addition, before the first bonding layer 53 is formed, an additional hydrophilic material layer may be formed on the surface of the reflective electrode 25.

The ohmic electrode 29 may be covered by the second bonding layer 55. The second bonding layer 55 transmits light generated from the first LED stack 23.

The third bonding layer 57 bonds the third LED stack 43 to the second LED stack 33. As in the second bonding layer 55, the third bonding layer 57 may be formed of a transparent organic material, a transparent inorganic material, or a transparent spin-on glass. As shown in the figure, the third bonding layer 57 may abut the second LED stack 33 and the second color filter 47. As described above, the hydrophilic material layer 58 may be formed on the second color filter 47, and the third bonding layer 57 may abut the hydrophilic material layer 58. In some exemplary embodiments, an additional hydrophilic material layer may be further formed on the surface of the second LED stack 33.

The first protective layer 61 covers the sub-pixel R, G, B. The first protective layer 61 may be formed of silicon oxide or silicon nitride.

The light blocking material 63 surrounds the sub-pixel R, G, B. The light blocking material 63 may be formed of a reflective white material or a light-absorbing black material. For example, the light blocking material 63 may be formed of white PSR or black epoxy. The light blocking material 63 may block light emitted through side surfaces of the sub-pixels R, G, B to prevent light interference between the sub-pixels.

A second protective layer 65 may be formed on the first protective layer 61 and the light blocking material 63, and a third protective layer 67 may be formed on the second protective layer 65.

As shown in fig. 4 and 5, the interconnection lines 71, 73, 75 may be disposed substantially orthogonal to the reflective electrode 25. The interconnection lines 71, 75 may be disposed on the third protective layer 67 and may be connected to the third-1 ohmic electrode 49 and the first-1 ohmic electrode 29 through connection portions 71a, 75a, respectively. In the illustrated exemplary embodiment, the first, second, and third protective layers 61, 65, and 67 may have openings exposing the third-1 ohmic electrodes 49 and the first-1 ohmic electrodes 29.

The interconnection line 73 may be disposed between the second protective layer 65 and the third protective layer 67, and may be connected to the second-1 ohmic electrode 39 through a connection portion 73 a. In this embodiment, the first protective layer 61 and the second protective layer 65 have openings that expose the second-1 ohmic electrode 39.

In addition, the connection portions 77a, 77b are provided between the second protective layer 65 and the third protective layer 67, and electrically connect the electrode pads 46, 36 to the reflective electrodes 25. In the illustrated exemplary embodiment, the first and second protective layers 61 and 65 may have openings exposing the electrode pads 36 and 46 and the reflective electrode 25.

The interconnection lines 71 and 73 are insulated from each other by the third protective layer 67, and thus may be disposed to overlap each other in the vertical direction.

Although the electrode of each pixel is described as being connected to the data line and the scan line, the interconnection lines 71, 75 are described as being disposed on the third protective layer 67, and the interconnection line 73 is described as being disposed between the second protective layer 65 and the third protective layer 67, the inventive concept is not limited thereto. For example, all of the interconnect lines 71, 75 and the interconnect line 73 may be formed on the second protective layer 65 and covered by the third protective layer 67, and the connection portions 71a, 75a may be formed on the third protective layer 67.

Next, a method of manufacturing the display apparatus 1000A according to an exemplary embodiment will be described.

Fig. 7A, 7B, 7C, 8A, 8B, 9A, 9B, 10A, 10B, 11A, 11B, 12A, 12B, 13A, 13B, 14A, 14B, 15A, 15B, 16A, 16B, 17A, 17B, 18, 19A, and 19B are schematic plan and sectional views illustrating a method of manufacturing a display device according to an exemplary embodiment.

First, referring to fig. 7A, a first LED stack 23 is grown on a first substrate 21. The first substrate 21 may be, for example, a GaAs substrate. In addition, the first LED stack 23 may be formed of an AlGaInP-based semiconductor layer, and includes a first conductive type semiconductor layer 23a, an active layer, and a second conductive type semiconductor layer 23 b.

Then, a reflective electrode 25 is formed on the first LED stack 23. The reflective electrode 25 may Be formed of, for example, an Au-Zn alloy or an Au-Be alloy.

The reflective electrode 25 may be formed by, for example, a lift-off process, and may be subjected to patterning to have a specific shape. For example, the reflective electrode 25 may be patterned to have a width corresponding to all the sub-pixels R, G, B and a length connecting a plurality of pixels. However, the inventive concept is not limited thereto. In some exemplary embodiments, the reflective electrode 25 may be formed over the entire upper surface of the first LED stack 23 without patterning, or may be subjected to patterning after being formed thereon.

The reflective electrode 25 may form an ohmic contact with the second conductive type semiconductor layer 23b (e.g., p-type semiconductor layer) of the first LED stack 23.

Referring to fig. 7B, a second LED stack 33 is grown on the second substrate 31, and a second-2 ohmic electrode 35 and a first color filter 37 are formed on the second LED stack 33. The second LED stack 33 may be formed of a GaN-based semiconductor layer, and may include a first conductive type semiconductor layer 33a, a GaInN well layer, and a second conductive type semiconductor layer 33 b. The second substrate 31 is a substrate on which a GaN-based semiconductor layer can be grown, and may be different from the first substrate 21. For example, the GaInN composition of the second LED stack 33 may be determined such that the second LED stack 33 may emit green light. The second-2 ohmic electrode 35 forms an ohmic contact with the second conductive type semiconductor layer 33b (e.g., p-type semiconductor layer) of the second LED stack 33.

Referring to fig. 7C, a third LED stack 43 is grown on the third substrate 41, and a third-2 ohmic electrode 45 and a second color filter 47 are formed on the third LED stack 43. The third LED stack 43 may be formed of a GaN-based semiconductor layer, and may include a first conductive type semiconductor layer 43a, a GaInN well layer, and a second conductive type semiconductor layer 43 b. The third substrate 41 is a substrate on which a GaN-based semiconductor layer can be grown, and may be different from the first substrate 21. For example, the GaInN composition of the third LED stack 43 may be determined such that the third LED stack 43 may emit blue light. The third-2 ohmic electrode 45 forms an ohmic contact with the second conductive type semiconductor layer 43b (e.g., p-type semiconductor layer) of the third LED stack 43.

The first color filter 37 and the second color filter 47 may be substantially the same as those described above, and thus, a detailed description thereof will be omitted in order to avoid redundancy.

The first LED stack 23, the second LED stack 33, and the third LED stack 43 are grown on different substrates, respectively, and the order of forming the first to third LED stacks is not particularly limited.

Referring to fig. 8A and 8B, the first LED stack 23 of fig. 7A is bonded to the upper side of the support substrate 51 via the first bonding layer 53. The reflective electrode 25 may be disposed to face the support substrate 51, and may be bonded to the first bonding layer 53. The first substrate 21 is removed from the first LED stack 23 by chemical etching or the like. Thus, the upper surface of the first conductive type semiconductor layer 23a of the first LED stack 23 is exposed. In some exemplary embodiments, a roughened surface may be formed on the exposed surface of the first conductive type semiconductor layer 23a by surface texturing.

A first-1 ohmic electrode 29 is then formed on the exposed surface of the first LED stack 23. The ohmic electrode 29 may be formed of, for example, an Au-Te alloy or an Au-Ge alloy. The ohmic electrode 29 may be formed in each pixel region. Alternatively, the ohmic electrode 29 may be formed in the first subpixel R and may be omitted in the second subpixel G or the second subpixel B. As shown in the drawing, the ohmic electrode 29 may include a pad region and an extension portion. As shown in the drawing, the extending portion may extend substantially in the longitudinal direction of the reflective electrode 25.

Referring to fig. 9A and 9B, the first LED stack 23 is subjected to patterning so as to be divided into regions corresponding to the sub-pixels R, G, B. Each of the divisional areas of the first LED stack 23 may be disposed on the reflective electrode 25. The first-1 ohmic electrode 29 may be disposed in a region corresponding to the first subpixel R. By patterning the first LED stack 23, the reflective electrode 25 is exposed, and a surface of the first bonding layer 53 may also be partially exposed. In other exemplary embodiments, an insulating layer may be disposed on the first bonding layer 53, and thus, a surface of the first bonding layer 53 may not be exposed.

Referring to fig. 10A and 10B, the second LED stack 33 of fig. 7B is bonded to the upper surface of the first LED stack 23 via the second bonding layer 55. The first color filter 37 is disposed to face the first LED stack 23 and is bonded to the second bonding layer 55. A hydrophilic material layer 56 may be formed on the first color filter 37, and the second bonding layer 55 may abut the hydrophilic material layer 56. In some exemplary embodiments, a hydrophilic material layer may be further formed on the first LED stack 23. The second substrate 31 is removed from the second LED stack 33 by laser lift-off or chemical lift-off. Thus, the upper surface of the first conductive type semiconductor layer 33a of the second LED stack 33 is exposed. In some exemplary embodiments, a roughened surface may be formed on the exposed surface of the first conductive type semiconductor layer 33a by surface texturing.

Next, the second-1 ohmic electrode 39 is formed on the first conductive type semiconductor layer 33 a. As shown in fig. 10A, the second-1 ohmic electrode 39 may include a pad region and an extension portion, as shown in the drawing. The extended portion may extend substantially in the longitudinal direction of the reflective electrode 25. The second-1 ohmic electrode 39 forms ohmic contact with the first conductive type semiconductor layer 33 a.

The second-1 ohmic electrode 39 may be formed in a region corresponding to the second subpixel G, and may be omitted in regions corresponding to the first subpixel R and the third subpixel B.

Referring to fig. 11A and 11B, the second LED stack 33 is subjected to patterning so as to be divided into regions corresponding to the sub-pixels R, G, B. The divided second LED stacks 33 are arranged to correspond to the divided first LED stacks 23, respectively.

More specifically, because the second LED stack 33 is subjected to patterning, the second-2 ohmic electrode 35 is exposed. Then, in the region of the second subpixel G, an electrode pad 36 is formed on the second-2 ohmic electrode 35. The electrode pad 36 may be restrictively disposed in an upper region of the first LED stack 23 of the second subpixel G. In the illustrated exemplary embodiment, the second LED stack 33 is additionally removed from the regions corresponding to the first and second sub-pixels R and G.

Since the exposed second-2 ohmic electrode 35 is removed in the first subpixel R, the first color filter 37 is exposed, and the pad region of the first-1 ohmic electrode 29 is exposed by patterning the exposed first color filter 37.

In addition, the first color filter 37 and the second bonding layer 55 may be removed to expose some regions of the reflective electrode 25.

Referring to fig. 12A and 12B, the third LED stack 43 of fig. 7B is bonded to the upper side of the second LED stack 33 via a third bonding layer 57. The second color filter 47 is disposed to face the second LED stack 33 and bonded to the third bonding layer 57. The hydrophilic material layer 58 may be formed on the second color filter 47 before other layers. In some exemplary embodiments, an additional hydrophilic material layer may be formed on the second LED stack 33.

The third substrate 41 may be removed from the third LED stack 43 by laser lift-off or chemical lift-off. In this way, the upper surface of the first conductive type semiconductor layer 43a of the third LED stack 43 is exposed. In some exemplary embodiments, a roughened surface may be formed on the exposed surface of the first conductive type semiconductor layer 43a by surface texturing.

Next, a third-1 ohmic electrode 49 is formed on the first conductive type semiconductor layer 43 a. The third-1 ohmic electrode 49 forms ohmic contact with the first conductive type semiconductor layer 43 a. As shown in fig. 12A, the third-1 ohmic electrode 49 may include a pad region and an extension portion. Here, the extended portion may extend substantially in the longitudinal direction of the reflective electrode 25.

The third-1 ohmic electrode 49 may be formed in a region corresponding to the third subpixel B, and may be omitted in regions of the first and second subpixels R and B.

Referring to fig. 13A and 13B, the third LED stack 43 is subjected to patterning so as to be divided into regions corresponding to the sub-pixels R, G, B. The divided regions of the third LED stack 43 may correspond to the divided regions of the first LED stack 23, respectively.

More specifically, because the third LED stack 43 is subjected to patterning, the third-2 ohmic electrode 45 is exposed. Then, in the region of the third subpixel B, an electrode pad 46 is formed on the third-2 ohmic electrode 45. The electrode pad 46 may be restrictively disposed in an upper region of the first LED stack 23 of the third subpixel B. In the illustrated exemplary embodiment, the third LED stack 43 is additionally removed from the regions corresponding to the first and second sub-pixels R and G.

Since the third-2 ohmic electrode 45 is removed, the second color filter 47 is exposed, and the pad region of the second-1 ohmic electrode 39, the electrode pad 36, and the pad region of the first-1 ohmic electrode 29 are exposed by sequentially patterning the exposed second color filter 47, the hydrophilic material layer 58, and the third bonding layer 57.

In addition, the second color filter 47 and the second bonding layer 55 may be removed to expose some regions of the reflective electrode 25.

Then, referring to fig. 14A and 14B, the first protective layer 61 is formed. The first protective layer 61 covers the third LED stack 43 and the second color filter 47, and also covers the exposed reflective electrode 25, the electrode pad 46, the pad region of the second-1 ohmic electrode 39, the electrode pad 36, and the pad region of the first-1 ohmic electrode 29. The first protective layer 61 may cover substantially the entire upper portion of the support substrate 51.

Then, referring to fig. 15A and 15B, the second color filter 47 surrounding the sub-pixel R, G, B is exposed by patterning the first protective layer 61. Then, the reflective electrode 25 is exposed by sequentially removing the second color filter 47, the hydrophilic material layer 58, the third bonding layer 57, the first color filter 37, the hydrophilic material layer 56, and the second bonding layer 55. The surface of the first bonding layer 53 can be exposed by sequentially removing the above-described layers in the region between the pixels. In this manner, a trench is formed around the sub-pixel R, G, B to surround the sub-pixel.

Referring to fig. 16A and 16B, a light blocking material layer may be formed in a trench surrounding the sub-pixel R, G, B. A layer of light blocking material is disposed around the sub-pixel R, G, B. The light blocking material layer 63 may be formed of, for example, black epoxy or white PSR, and may prevent light interference between the sub-pixels and the pixels by blocking light emitted through the side surface of each of the sub-pixels R, G, B.

Then, referring to fig. 17A and 17B, a second protective layer 65 is formed to cover the first protective layer 61 and the light blocking material layer 63. Then, the first protective layer 61 and the second protective layer 65 are subjected to patterning so as to expose pad regions of the first-1 ohmic electrode 29, the second-1 ohmic electrode 39, and the third-1 ohmic electrode 49 in addition to the electrode pads 36, 46. Further, the reflective electrode 25 is exposed in the vicinity of the electrode pads 36, 46. In some exemplary embodiments, the second protective layer 65 may be omitted.

Referring to fig. 18, the interconnection lines 73 and the connection portions 73a, 77b are formed. The connection portion 73a connects the second-1 ohmic electrode 39 to the interconnection line 73, the connection portion 77a connects the electrode pad 46 to the reflective electrode 25, and the connection portion 77b connects the electrode pad 36 to the reflective electrode 25.

Then, referring to fig. 19A and 19B, a third protective layer 67 is formed. The third protective layer 67 covers the interconnection lines 73 and the connection portions 73a, 77 b. Here, the third protective layer 67 exposes pad regions of the first-1 ohmic electrode 29 and the third-1 ohmic electrode 49.

Next, the interconnection lines 71, 75 and the connection portions 71a, 75a are formed on the third protective layer 67. The connection portion 71a connects the interconnection line 71 to the third-1 ohmic electrode 49, and the connection portion 75a connects the interconnection line 75 to the first-1 ohmic electrode 29.

In this way, the display device 1000A of fig. 4 and 5 can be provided.

Although the pixels are described as being driven in a passive matrix manner, the inventive concept is not limited thereto, and in some exemplary embodiments, the pixels may be driven in an active matrix manner.

Fig. 20 is a schematic cross-sectional view of a display apparatus according to another exemplary embodiment.

Referring back to fig. 7A, the reflective electrode 25 is directly formed on the second conductive type semiconductor layer 23b, however, the inventive concept is not limited thereto. Specifically, referring to fig. 20, the reflective electrode 25 may include an ohmic contact layer 25a and a reflective layer 25 b. The ohmic contact layer 25a may Be formed of, for example, an Au-Zn alloy or an Au-Be alloy, and the reflective layer 25b may Be formed of Al, Ag, or Au. When the reflective layer 25b is formed of Au, the reflective layer 25b may exhibit a relatively high reflectance with respect to light (e.g., red light) generated from the first LED stack 23, and may exhibit a relatively low reflectance with respect to light (e.g., green or blue light) generated from the second and third LED stacks 33 and 43. Accordingly, the reflective layer 25b may reduce interference of light generated from the second and third LED stacks 33 and 43 and traveling toward the support substrate 51 by absorbing light from the second and third LED stacks 33 and 43.

The insulating layer 27 may be disposed between the reflective layer 25b and the second conductive type semiconductor layer 23 b. The insulating layer 27 may have an opening exposing the second conductive type semiconductor layer 23b, and the ohmic contact layer 25a may be formed in the opening of the insulating layer 27.

Since the reflective layer 25b covers the insulating layer 27, an omnidirectional reflector may be formed by a stacked structure of the first LED stack 23 having a relatively high refractive index, the insulating layer 27 having a relatively low refractive index, and the reflective layer 25 b. The reflective layer 25b covers 50% or more of the area of the first LED stack 23 or most of the first LED stack 23, thereby improving the luminous efficacy.

In an exemplary embodiment, the reflective electrode 25 may be formed by the following process. First, a first LED stack 23 is grown on a substrate 21, and an insulating layer 27 is formed on the first LED stack 23. Then, an opening is formed by patterning the insulating layer 27. For example, SiO is formed on the first LED stack 23₂And a photoresist is deposited thereon, followed by photolithography and development to form a photoresist pattern. Thereafter, SiO is patterned by a photoresist pattern as an etching mask₂The layer is subjected to patterning, thereby forming an insulating layer 27 having an opening formed therein.

Thereafter, an ohmic contact layer 25a is formed in the opening of the insulating layer 27. The ohmic contact layer 25a may be formed by a lift-off process or the like. After the ohmic contact layer 25a is formed, a reflective layer 25b is formed to cover the ohmic contact layer 25a and the insulating layer 27. The reflective layer 25b may be formed by a lift-off process or the like. As shown in the drawing, the reflective layer 25b may partially or completely cover the ohmic contact layer 25 a. The reflective electrode 25 is formed by the ohmic contact layer 25a and the reflective layer 25 b. The shape of the reflective electrode 25 may be substantially the same as that of the reflective electrode described above, and thus, a detailed description thereof will be omitted in order to avoid redundancy.

According to an exemplary embodiment, a plurality of pixels may be formed at a wafer level, thereby eliminating the need to separately mount light emitting diodes.

Fig. 21 is a schematic plan view of a display device according to another exemplary embodiment, and fig. 22 is a schematic cross-sectional view of a light emitting diode pixel for a display according to an exemplary embodiment.

Referring to fig. 21, a display apparatus 2000 according to an exemplary embodiment includes a support substrate 251 and a plurality of pixels 200 disposed on the support substrate 251. Each pixel 200 includes a first sub-pixel R, a second sub-pixel G, and a third sub-pixel B.

Referring to fig. 22, the support substrate 251 supports the LED stacks 223, 233, 243. The support substrate 251 may include a circuit on a surface thereof or in the same, but the inventive concept is not limited thereto. The support substrate 251 may include, for example, a Si substrate or a Ge substrate.

The first subpixel R comprises a first LED stack 223, the second subpixel G comprises a second LED stack 233, and the third subpixel B comprises a third LED stack 243. The first subpixel R may emit light through the first LED stack 223, the second subpixel G may emit light through the second LED stack 233, and the third subpixel B may emit light through the third LED stack 243. The first, second and third LED stacks 223, 233, 243 may be driven independently.

As shown in the figure, the first LED stack 223, the second LED stack 233, and the third LED stack 243 may be disposed on different planes. As shown in the figure, the second LED stack 233 may be disposed on a higher plane than the first LED stack 223, and the third LED stack 243 may be disposed on a higher plane than the second LED stack 233. In addition, the first, second, and third LED stacks 223, 233, and 243 are separated from each other in a horizontal direction and may not overlap with each other. Accordingly, light generated from the first LED stack 223 may be emitted to the outside without passing through the second and third LED stacks 233 and 243, and light generated from the second LED stack 233 may be emitted to the outside without passing through the third LED stack 243.

Each of the first, second, and third LED stacks 223, 233, and 243 includes an n-type semiconductor layer, a p-type semiconductor layer, and an active layer interposed between the n-type and p-type semiconductor layers. The active layer may have a multiple quantum well layer structure. The first, second and third LED stacks 223, 233 and 243 may include different active layers to emit light having different wavelengths. For example, the first LED stack 223 may be an inorganic light emitting diode emitting red light, the second LED stack 233 may be an inorganic light emitting diode emitting green light, and the third LED stack 243 may be an inorganic light emitting diode emitting blue light. In an exemplary embodiment, the first LED stack 223 may include a GaInP-based well layer, and the second and third LED stacks 233 and 243 may include a GaInN-based well layer. However, the inventive concept is not limited thereto, and the wavelengths of light emitted from the first, second, and third LED stacks 223, 233, and 243 may be changed. For example, the first, second, and third LED stacks 223, 233, and 243 may emit green, blue, and red light, respectively, or may emit blue, green, and red light, respectively.

Fig. 23 is a schematic circuit diagram of a display device according to an exemplary embodiment.

Referring to fig. 23, the display device according to an exemplary embodiment may be driven in a passive matrix manner. As described with reference to fig. 21 and 22, one pixel includes a first subpixel R, a second subpixel G, and a third subpixel B. The first LED stack 223 of the first subpixel R emits light having a first wavelength, the second LED stack 233 of the second subpixel G emits light having a second wavelength, and the third LED stack 243 of the third subpixel B emits light having a third wavelength. The anode electrode of the first subpixel R, the anode electrode of the second subpixel G, and the anode electrode of the third subpixel B may be connected to a common line, for example, a data line Vdata 225, and the cathode electrode of the first subpixel R, the cathode electrode of the second subpixel G, and the cathode electrode of the third subpixel B may be connected to different lines, for example, scan lines Vscan271, 273, 275.

For example, in the first pixel, the anode of the first sub-pixel R, the anode of the second sub-pixel G, and the anode of the third sub-pixel B are commonly connected to the data line Vdata1, and the cathode of the first sub-pixel R, the cathode of the second sub-pixel G, and the cathode of the third sub-pixel B are respectively connected to the scan lines Vscan1-1, Vscan1-2, Vscan 1-3. Therefore, the sub-pixels R, G, B in the same pixel can be driven individually.

In addition, each LED stack 223, 233, 243 may be driven by pulse width modulation or by varying the magnitude of the current, thereby controlling the brightness of each sub-pixel. Alternatively, the brightness may be adjusted by adjusting the areas of the first, second, and third LED stacks 223, 233, and 243. For example, an LED stack (e.g., the first LED stack 223) emitting light with low visibility may be formed to have a larger area than the second LED stack 233 or the third LED stack 243.

Fig. 24 is a schematic plan view of a display apparatus according to an exemplary embodiment.

Referring to fig. 24, a display apparatus 2000A according to an exemplary embodiment includes a plurality of pixels 200A disposed on a support substrate 251. Each sub-pixel R, G, B is connected to the reflective electrode 225 and interconnect lines 271, 273, 275. As shown in fig. 23, the reflective electrode 225 may correspond to the data line Vdata, and the interconnection lines 271, 273, 275 may correspond to the scan line Vscan.

The pixels 200A may be arranged in a matrix form in which anodes of the sub-pixels R, G, B in each pixel are commonly connected to the reflective electrode 225, and cathodes of the sub-pixels R, G, B in each pixel are respectively connected to interconnection lines 271, 273, 275 that are isolated from each other. The connection portions 271a, 273a, 275a may connect the interconnection lines 271, 273, 275 to the sub-pixel R, G, B.

Fig. 25 is an enlarged plan view of one pixel 200A of the display device of fig. 24, and fig. 26A, 26B, 26C, and 26D are schematic sectional views taken along line a-a, line B-B, line C-C, and line D-D of fig. 25, respectively.

Referring to fig. 24, 25, 26A, 26B, 26C, and 26D, a display device 2000A may include a supporting substrate 251, a plurality of pixels 200A, a first subpixel R, a second subpixel G, a third subpixel B, a first LED stack 223, a second LED stack 233, a third LED stack 243, a reflective electrode 225 (or a first-2 ohmic electrode), a first-1 ohmic electrode 229, a second-1 ohmic electrode 239, a second-2 ohmic electrode 235, a third-1 ohmic electrode 249, a third-2 ohmic electrode 245, a hydrophilic material layer 256, 258, a first bonding layer 253, a second bonding layer 255, a third bonding layer 257, a first protective layer 261, a light blocking material 263, a second protective layer 265, interconnection lines 271, 273, 275, and connection portions 271a, 273a, 275a, 277B.

The support substrate 251 supports the LED stacks 223, 233, 243. The support substrate 251 may include circuits on or in a surface thereof, but is not limited thereto. The support substrate 251 may include, for example, a glass substrate, a sapphire substrate, a Si substrate, or a Ge substrate.

The first LED stack 223 includes a first conductive type semiconductor layer 223a and a second conductive type semiconductor layer 223 b. The second LED stack 233 includes a first conductive type semiconductor layer 233a and a second conductive type semiconductor layer 233 b. The third LED stack 243 includes a first conductive type semiconductor layer 243a and a second conductive type semiconductor layer 243 b. In addition, the active layer may be interposed between the first and second conductive type semiconductor layers 223a and 223b, between the first and second conductive type semiconductor layers 233a and 233b, and between the first and second conductive type semiconductor layers 243a and 243b, respectively.

In an exemplary embodiment, each of the first conductive type semiconductor layers 223a, 233a, 243a may be an n-type semiconductor layer, and each of the second conductive type semiconductor layers 223b, 233b, 243b may be a p-type semiconductor layer. In some exemplary embodiments, a roughened surface may be formed on the surface of the first conductive type semiconductor layer 223a, 233a, 243a by surface texturing. However, the inventive concept is not so limited and the type of semiconductor in each LED stack may vary.

The first LED stack 223 is disposed close to the support substrate 251, the second LED stack 233 is disposed at a higher plane than the first LED stack 223, and the third LED stack 243 is disposed at a higher plane than the second LED stack 233. In addition, the second LED stack 233 is spaced apart from the first LED stack 223 in the horizontal direction, and thus does not overlap the first LED stack 223. The third LED stack 243 is horizontally spaced apart from the first and second LED stacks 223, 233 and thus does not overlap the first and second LED stacks 223, 233. Accordingly, the light generated from the first LED stack 223 may be emitted to the outside without passing through the second and third LED stacks 33 and 43. In addition, light generated from the second LED stack 233 may be emitted to the outside without passing through the third LED stack 243.

The materials forming the first, second, and third LED stacks 223, 233, and 243 are substantially the same as those described with reference to fig. 22, and thus, a detailed description thereof will be omitted in order to avoid redundancy.

The reflective electrode 225 forms an ohmic contact with a lower surface of the first LED stack 223 (e.g., the second conductive type semiconductor layer 223 b). The reflective electrode 225 may be continuously disposed under the first, second, and third sub-pixels R, G, and B. In addition, the reflective electrode 225 may be commonly connected to the plurality of pixels 200a and may serve as a data line Vdata.

The reflective electrode 225 may be formed of, for example, a material layer forming an ohmic contact with the second conductive type semiconductor layer 223b of the first LED stack 223, and may include a reflective layer that may reflect light (e.g., red light) generated from the first LED stack 223.

The reflective electrode 225 may include an ohmic reflective layer, and may Be formed of, for example, an Au-Zn alloy or an Au-Be alloy. These alloys have high reflectance for light in the red range and form ohmic contact with the second conductive type semiconductor layer 223 b.

The first-1 ohmic electrode 229 forms an ohmic contact with the first conductive type semiconductor layer 223a of the first subpixel R. The first-1 ohmic electrode 229 may include a pad region and an extension portion (see fig. 28A), and as shown in fig. 26B, the connection portion 275a may be connected to the pad region of the first-1 ohmic electrode 229.

The second-1 ohmic electrode 239 forms an ohmic contact with the first conductive type semiconductor layer 233a of the second LED stack 233. The second-1 ohmic electrode 239 may include a pad region and an extension portion (see fig. 30A), and as shown in fig. 26C, the connection portion 273a may be connected to the pad region of the second-1 ohmic electrode 239.

The second-2 ohmic electrode 235 forms an ohmic contact with the second conductive type semiconductor layer 233b of the second LED stack 233. The second-2 ohmic electrode 235 may be transparent to light generated from the first LED stack 223 and may be formed of, for example, a metal layer or a conductive oxide layer. Alternatively, the second-2 ohmic electrode 235 may not be transparent and may include a reflective metal layer.

The electrode pad 236 may be formed on the second-2 ohmic electrode 235. The electrode pad 236 is disposed in a limited region of the second-2 ohmic electrode 235, and the connection portion 277b may be connected to the electrode pad 236.

The third-1 ohmic electrode 249 makes ohmic contact with the first conductive type semiconductor layer 243a of the third LED stack 243. The third-1 ohmic electrode 249 may include a pad region and an extension portion (see fig. 32A), and as shown in fig. 26D, the connection portion 271a may be connected to the pad region of the third-1 ohmic electrode 249.

The third-2 ohmic electrode 245 forms an ohmic contact with the second conductive type semiconductor layer 243b of the third LED stack 243. The third-2 ohmic electrode 245 may be transparent to the light generated from the second LED stack 233 and may be formed of, for example, a metal layer or a conductive oxide layer. Alternatively, the third-2 ohmic electrode 245 may not be transparent and may include a reflective metal layer.

The electrode pad 246 is formed on the third-2 ohmic electrode 245. The electrode pad 246 is disposed in a limited region of the third-2 ohmic electrode 245. The connection portion 277a may be connected to the electrode pad 246.

The reflective electrode 225, the second-2 ohmic electrode 235 and the third-2 ohmic electrode 245 may assist current diffusion by ohmic contact with the p-type semiconductor layer of each LED stack, and the first-1 ohmic electrode 229, the second-1 ohmic electrode 239 and the third-1 ohmic electrode 249 may assist current diffusion by ohmic contact with the n-type semiconductor layer of each LED stack.

The first bonding layer 253 bonds the first LED stack 223 to the supporting substrate 251. As shown in the figure, the reflective electrode 225 may abut the first bonding layer 253. The first bonding layer 253 may be continuously disposed under the first, second, and third subpixels R, G, and B. The first bonding layer 253 may be a light transmissive layer or an opaque layer. The first bonding layer 253 may be formed of an organic material or an inorganic material. Examples of organic materials may include SU8, poly (methacrylic acid)Methyl formate) (PMMA), polyimide, parylene, benzocyclobutene (BCB), or others, and examples of the inorganic material may include Al₂O₃、SiO₂、SiN_xOr otherwise. The organic material layer may be bonded under high vacuum and high pressure conditions, and the inorganic material layer may be bonded under high vacuum after the surface energy is changed using plasma by, for example, chemical mechanical polishing to planarize the surface of the inorganic material layer. In particular, the first bonding layer 253 may include a black epoxy capable of absorbing light to improve the contrast of the display device. The first bonding layer 253 can also be formed of transparent spin-on glass.

The second bonding layer 255 may cover the first LED stack 223 and bond the second LED stack 233 to the reflective electrode 225. The second bonding layer 255 may also be disposed below the third LED stack 243. The second bonding layers 255 of the first, second, and third sub-pixels R, G, and B may be isolated from each other.

The second bonding layer 255 may be formed of a transparent organic material or a transparent inorganic material. Examples of the organic material may include SU8, poly (methyl methacrylate) (PMMA), polyimide, parylene, benzocyclobutene (BCB), or others, and examples of the inorganic material may include Al₂O₃、SiO₂、SiN_xOr otherwise. In addition, the second bonding layer 255 may be formed of transparent spin-on glass.

As shown in the figure, the second bonding layer 255 may adjoin the first LED stack 223 in the region of the first subpixel R. In addition, the second bonding layer 255 may adjoin the second-2 ohmic electrode 235 in the region of the second subpixel G. In addition, an additional hydrophilic material layer 256 may be further formed between the second bonding layer 255 and the second-2 ohmic electrode 235. The hydrophilic material layer 256 may remain in the regions of the first and third sub-pixels R and B.

The hydrophilic material layer 256 changes the surface properties of the second bonding layer 255 from hydrophobic to hydrophilic, thereby improving the adhesive strength of the second bonding layer 255 to prevent the second bonding layer 255 from peeling off during manufacture or use. In some exemplary embodiments, the hydrophilic may be omittedA layer of performance material 256. The hydrophilic material layer 256 may be formed by depositing SiO on the surface of the second-2 ohmic electrode 235₂Or by plasma modification of the surface of the second-2 ohmic electrode 235.

In some exemplary embodiments, a hydrophilic material layer may also be formed on the surface of the first LED stack 223 or the reflective electrode 225. In addition, an additional hydrophilic material layer may be added to the surface of the reflective electrode 225 or the support substrate 251.

The ohmic electrode 229 may be covered by the second bonding layer 255. The second bonding layer 255 transmits light generated from the first LED stack 223.

The third bonding layer 257 bonds the third LED stack 243 to the second LED stack 233. As in the second bonding layer 255, the third bonding layer 257 may be formed of a transparent organic material, a transparent inorganic material, or a transparent spin-on glass. As shown in the figure, the third bonding layer 257 may be disposed over the second bonding layer 255 in the region of the first subpixel R, and may cover the second LED stack 233 in the region of the second subpixel G. As described above, the hydrophilic material layer 258 is formed under the third-2 ohmic electrode 245, and the third bonding layer 257 may abut the hydrophilic material layer 258. In some exemplary embodiments, an additional hydrophilic material layer may be further formed on the second LED stack 233.

The first protection layer 261 covers the sub-pixel R, G, B. The first protection layer 261 may be formed of silicon oxide or silicon nitride.

The light blocking material 263 surrounds the sub-pixel R, G, B. The light blocking material 263 may be formed of a reflective white material or a light-absorbing black material. For example, the light blocking material 263 may be formed of white PSR or black epoxy. The light blocking material 263 blocks light emitted through the side surface of the sub-pixel R, G, B to prevent light interference between sub-pixels. The second protective layer 265 may be formed on the first protective layer 261 and the light blocking material 263.

As shown in fig. 24 and 25, the interconnection lines 271, 273, 275 may be disposed substantially orthogonal to the reflective electrode 225. The interconnection lines 271, 275 may be disposed on the second protective layer 265 and may be connected to the third-1 ohmic electrode 249 and the first-1 ohmic electrode 229 through connection portions 271a, 275a, respectively. In an exemplary embodiment, the first and second protective layers 261 and 265 have openings exposing the third-1 ohmic electrodes 249 and the first-1 ohmic electrodes 229.

The interconnection line 273 may be disposed between the first protective layer 261 and the second protective layer 265, and may be connected to the second-1 ohmic electrode 239 through a connection portion 273 a. In the illustrated exemplary embodiment, the first protective layer 261 has an opening exposing the second-1 ohmic electrode 239.

In addition, the connection portions 277a, 277b are disposed between the first protective layer 261 and the second protective layer 265, and electrically connect the electrode pads 246, 236 to the reflective electrode 225. In the illustrated exemplary embodiment, the first protection layer 261 may have an opening exposing the electrode pads 236, 246.

The interconnection lines 271 and 273 are insulated from each other by the second protective layer 265, and thus, may be disposed to overlap each other in the vertical direction.

Although the electrode of each pixel is described as being connected to the data line and the scan line, the interconnection lines 271, 275 are described as being disposed on the second protective layer 265, and the interconnection line 273 is described as being disposed between the first protective layer 261 and the second protective layer 265, the inventive concept is not limited thereto. For example, all the interconnection lines 271, 275, 273 may be formed on the first protective layer 261 and covered by the second protective layer 265, and the connection portions 271a, 275a may be formed on the second protective layer 265.

Next, a method of manufacturing the display device 2000A according to an exemplary embodiment will be described below.

Fig. 27 to 39 are schematic plan and sectional views illustrating a method of manufacturing a display apparatus according to an exemplary embodiment.

First, referring to fig. 27A, a first LED stack 223 is grown on a first substrate 221. The first substrate 221 may be, for example, a GaAs substrate. The first LED stack 223 may be formed of an AlGaInP-based semiconductor layer, and includes a first conductive type semiconductor layer 223a, an active layer, and a second conductive type semiconductor layer 223 b.

Then, a reflective electrode 225 is formed on the first LED stack 223. The reflective electrode 225 may Be formed of, for example, an Au-Zn alloy or an Au-Be alloy.

The reflective electrode 225 may be formed by a lift-off process or the like, and may be subjected to patterning to have a specific shape. For example, the reflective electrode 225 may be patterned to have a width corresponding to all of the sub-pixels R, G, B and a length connecting a plurality of pixels. However, the inventive concept is not limited thereto. Alternatively, the reflective electrode 225 may be formed over the upper surface of the first LED stack 223 without patterning, or may be subjected to patterning after being formed thereon.

The reflective electrode 225 may form an ohmic contact with the second conductive type semiconductor layer 223b (e.g., p-type semiconductor layer) of the first LED stack 223.

Referring to fig. 27B, a second LED stack 233 is grown on a second substrate 231, and a second-2 ohmic electrode 235 is formed on the second LED stack 233. The second LED stack 233 may be formed of a GaN-based semiconductor layer, and may include a first conductive type semiconductor layer 233a, a GaInN well layer, and a second conductive type semiconductor layer 233 b. The second substrate 231 is a substrate on which a GaN-based semiconductor layer can be grown, and may be different from the first substrate 221. For example, the GaInN composition of the second LED stack 233 may be determined such that the second LED stack 233 may emit green light. The second-2 ohmic electrode 235 forms an ohmic contact with the second conductive type semiconductor layer 233b (e.g., a p-type semiconductor layer).

Referring to fig. 27C, a third LED stack 243 is grown on the third substrate 241, and a third-2 ohmic electrode 245 is formed on the third LED stack 243. The third LED stack 243 may be formed of a GaN-based semiconductor layer, and may include a first conductive type semiconductor layer 243a, a GaInN well layer, and a second conductive type semiconductor layer 243 b. The third substrate 241 is a substrate on which a GaN-based semiconductor layer can be grown, and may be different from the first substrate 221. For example, the GaInN composition of the third LED stack 243 may be determined such that the third LED stack 243 may emit blue light. The third-2 ohmic electrode 245 forms an ohmic contact with the second conductive type semiconductor layer 243b (e.g., a p-type semiconductor layer).

Since the first LED stack 223, the second LED stack 233, and the third LED stack 243 may be grown on different substrates, the order of forming the first to third LED stacks is not particularly limited.

Referring to fig. 28A and 28B, the first LED stack 223 of fig. 27A is bonded to the upper side of the supporting substrate 251 via the first bonding layer 253. The reflective electrode 225 may be disposed to face the support substrate 251 and may be bonded to the first bonding layer 253. The first substrate 221 is removed from the first LED stack 223 by chemical etching or the like. In this way, the upper surface of the first conductive type semiconductor layer 223a of the first LED stack 223 is exposed. In some exemplary embodiments, a roughened surface may be formed on the exposed surface of the first conductive type semiconductor layer 223a by surface texturing or the like.

A first-1 ohmic electrode 229 is then formed on the exposed surface of the first LED stack 223. The ohmic electrode 229 may be formed of, for example, an Au-Te alloy or an Au-Ge alloy. The ohmic electrode 229 may be formed in each pixel region. The ohmic electrode 229 may be formed in the first subpixel R. As shown in the drawing, the ohmic electrode 229 may include a pad region and an extension portion. As shown in the drawing, the extended portion may extend substantially in the longitudinal direction of the reflective electrode 225.

Referring to fig. 29A and 29B, the first LED stack 223 is removed from a region excluding a region corresponding to the first subpixel R by patterning the first LED stack 223. The first-1 ohmic electrode 229 remains in the region of the first subpixel R. Since the first LED stack 223 is subjected to patterning, the reflective electrode 225 is exposed, and a surface of the first bonding layer 253 may also be partially exposed. In other exemplary embodiments, an insulating layer may be disposed on the first bonding layer 253, and thus, a surface of the first bonding layer 253 may not be exposed.

Referring to fig. 30A and 30B, the second LED stack 233 of fig. 27B is bonded to the upper side of the first LED stack 223 via the second bonding layer 255. The second-2 ohmic electrode 235 is disposed to face the first LED stack 23 and bonded to the second bonding layer 255. A hydrophilic material layer 256 may be formed on the second-2 ohmic electrode 235, and the second bonding layer 255 may adjoin the hydrophilic material layer 256. In some exemplary embodiments, a hydrophilic material layer may be further formed on the first LED stack 23. The second substrate 231 may be removed from the second LED stack 233 by laser lift-off or chemical lift-off. In this way, the upper surface of the first conductive type semiconductor layer 233a of the second LED stack 233 is exposed. In some exemplary embodiments, a roughened surface may be formed on the exposed surface of the first conductive type semiconductor layer 233a by surface texturing or the like.

Next, a second-1 ohmic electrode 239 is formed on the first conductive type semiconductor layer 233 a. The second-1 ohmic electrode 239 is formed in a region corresponding to the second subpixel G. As shown in fig. 30A, the second-1 ohmic electrode 239 may include a pad region and an extension portion. The extended portion may extend substantially in the longitudinal direction of the reflective electrode 225. The second-1 ohmic electrode 239 forms ohmic contact with the first conductive type semiconductor layer 233 a.

Referring to fig. 31A and 31B, the second LED stack 233 is removed from a region excluding a region corresponding to the second subpixel G in each pixel by patterning the second LED stack 233. The second LED stack 233 in the region of the second subpixel G is spaced apart from the first LED stack 223 in the horizontal direction so as not to overlap the first LED stack 223.

More specifically, because the second LED stack 233 is subjected to patterning, the second-2 ohmic electrode 235 is exposed. Then, in the region of the second subpixel G, an electrode pad 236 may be formed on the second-2 ohmic electrode 235. The electrode pad 236 may be restrictively disposed in the area of the second subpixel G. In an exemplary embodiment, the second LED stack 233 may be additionally removed from the region of the second subpixel G.

Since the exposed second-2 ohmic electrode 235 is removed, the hydrophilic material layer 256 or the second bonding layer 255 may be exposed.

Referring to fig. 32A and 32B, the third LED stack 243 of fig. 27C is bonded to the upper side of the second LED stack 233 via the third bonding layer 257. The third-2 ohmic electrode 245 is disposed to face the support substrate 251 and is bonded to the third bonding layer 257. The hydrophilic material layer 258 may be formed on the third-2 ohmic electrode 245 before other layers. In some exemplary embodiments, an additional hydrophilic material layer may be formed on the second LED stack 233.

The third substrate 241 may be removed from the third LED stack 243 by laser lift-off or chemical lift-off. In this way, the upper surface of the first conductive type semiconductor layer 243a of the third LED stack 243 is exposed. In some exemplary embodiments, a roughened surface may be formed on the exposed surface of the first conductive type semiconductor layer 243a by surface texturing or the like.

Next, a third-1 ohmic electrode 249 is formed on the first conductive type semiconductor layer 243 a. The third-1 ohmic electrode 249 is formed in a region corresponding to the third subpixel B. The third-1 ohmic electrode 249 forms ohmic contact with the first conductive type semiconductor layer 243 a. As shown in fig. 32A, the third-1 ohmic electrode 249 may include a pad region and an extended portion, and the extended portion may extend substantially in a longitudinal direction of the reflective electrode 225.

Referring to fig. 33A and 33B, the third LED stack 243 is removed from a region excluding a region corresponding to the third subpixel B in each pixel by patterning the third LED stack 243. The third LED stack 243 is horizontally isolated from the first and second LED stacks 223, 233.

More specifically, because the third LED stack 243 is patterned, the third-2 ohmic electrode 245 is exposed. Then, in the region of the third subpixel B, an electrode pad 246 is formed on the third-2 ohmic electrode 245. The electrode pad 246 may be restrictively disposed in the region of the third subpixel B. In an exemplary embodiment, the third LED stack 243 is additionally removed from the region of the third subpixel B.

The exposed third-2 ohmic electrode 245 is removed to expose the hydrophilic material layer 258 or the third bonding layer 257.

Then, referring to fig. 34A and 34B, the first protective layer 261 is formed. The first protective layer 261 covers the third LED stack 243 and the hydrophilic material layer 258. The first protective layer 261 may cover substantially the entire upper portion of the support substrate 251.

Then, referring to fig. 35A and 35B, the hydrophilic material layer 258 surrounding the sub-pixels R, G, B is exposed by patterning the first protective layer 261, and then the reflective electrode 225 is exposed by sequentially removing the hydrophilic material layer 258, the third bonding layer 257, the hydrophilic material layer 256, and the second bonding layer 255. The surface of the first bonding layer 253 can be exposed by sequentially removing the above layers in a region between pixels. As such, a trench is formed around the subpixel R, G, B to surround the subpixel.

Referring to fig. 36A and 36B, a light blocking material layer may be formed in the trench surrounding the sub-pixel R, G, B. A layer of light blocking material is disposed around the sub-pixel R, G, B. The light blocking material layer 263 may be formed of, for example, black epoxy or white PSR, and may prevent light interference between the sub-pixels and the pixels by blocking light emitted through the side surface of each of the sub-pixels R, G, B.

Then, referring to fig. 37A and 37B, the first protective layer 261, the hydrophilic material layer 258, the third bonding layer 257, the hydrophilic material layer 256, and the second bonding layer 255 are sequentially subjected to patterning to expose pad regions of the first-1 ohmic electrode 229, the second-1 ohmic electrode 239, and the third-1 ohmic electrode 249, and the electrode pads 236, 246.

Referring to fig. 38, an interconnection line 273 and connection portions 273a, 277b are formed. The connection portion 273a connects the second-1 ohmic electrode 239 to the interconnection line 273, the connection portion 277a connects the electrode pad 246 to the reflective electrode 225, and the connection portion 277b connects the electrode pad 236 to the reflective electrode 225.

Then, referring to fig. 39A and 39B, a second protective layer 265 is formed. The second protective layer 265 covers the interconnection lines 273 and the connection portions 273a, 277 b. Here, the second protective layer 265 exposes pad regions of the first-1 ohmic electrode 229 and the third-1 ohmic electrode 249.

Next, the interconnection lines 271, 275 and the connection portions 271a, 275a are formed on the second protective layer 265. The connection portion 271a connects the interconnection line 271 to the third-1 ohmic electrode 249, and the connection portion 275a connects the interconnection line 275 to the first-1 ohmic electrode 229.

Thus, the display device 2000A described with reference to fig. 24 and 25 is provided.

Although the pixels are described as being driven in a passive matrix manner, the inventive concept is not limited thereto, and the pixels may be driven in an active matrix manner in some exemplary embodiments.

Fig. 40 is a schematic cross-sectional view of a display apparatus according to another exemplary embodiment. Although the reflective electrode 225 is directly formed on the second conductive type semiconductor layer 223b in fig. 27A, the inventive concept is not limited thereto.

Specifically, referring to fig. 40, the reflective electrode 225 may include an ohmic contact layer 225a and a reflective layer 225 b. The ohmic contact layer 225a may Be formed of, for example, Au-Zn alloy or Au-Be alloy, and the reflective layer 225b may Be formed of Al, Ag, or Au. In particular, when the reflective layer 225b is formed of Au, the reflective layer 225b may exhibit a relatively high reflectance to light (e.g., red light) generated from the first LED stack 223, and may exhibit a relatively low reflectance to light (e.g., green or blue light) generated from the second and third LED stacks 233 and 243. When the reflective layer 225b is formed of Al or Ag, the reflective layer 225b may exhibit relatively high reflectivity for red, green, and blue light, thereby improving light extraction efficiency of the first, second, and third LED stacks 223, 233, and 243.

The insulating layer 227 may be disposed between the reflective layer 225b and the second conductive type semiconductor layer 223 b. The insulating layer 227 may have an opening exposing the second conductive type semiconductor layer 223b, and an ohmic contact layer 225a may be formed in the opening of the insulating layer 227.

Since the reflective layer 225b covers the insulating layer 227, an omni-directional reflector may be formed by a stacked structure of the first LED stack 223 having a relatively high refractive index, the insulating layer 227 having a relatively low refractive index, and the reflective layer 225 b.

In an exemplary embodiment, the reflective electrode 225 may be formed by the following process. First, a first LED stack 223 is grown on a substrate 221, and an insulating layer 227 is formed on the first LED stack 223. Then, an opening is formed by patterning the insulating layer 227. For example, SiO is formed on the first LED stack 223₂And a photoresist is deposited thereon, followed by photolithography and development to form a photoresist pattern. Thereafter, by acting as an etching maskPatterning of the photoresist to SiO₂The layer is subjected to patterning, thereby forming an insulating layer 227 having an opening formed therein.

Thereafter, an ohmic contact layer 225a is formed in the opening of the insulating layer 227. The ohmic contact layer 225a may be formed by a lift-off process or the like. After the ohmic contact layer 225a is formed, a reflective layer 225b is formed to cover the ohmic contact layer 225a and the insulating layer 227. The reflective layer 225b may be formed by a lift-off process or the like. As shown in the figure, the reflective layer 225b may partially or completely cover the ohmic contact layer 225 a. The reflective electrode 225 is formed of an ohmic contact layer 225a and a reflective layer 225 b. The shape of the reflective electrode 225 may be substantially the same as that of the reflective electrode described above, and thus, a detailed description thereof will be omitted.

Although the first LED stack 223 is described as being formed of AlGaInP-based semiconductor layers to emit red light, the inventive concept is not limited thereto. For example, the first LED stack 223 may be adapted to emit green or blue light. In this case, the first LED stack 223 may be formed of an AlGaInN-based semiconductor layer. In addition, the second LED stack 233 or the third LED stack 243 may be formed of an AlGaInP-based semiconductor layer.

Fig. 41 is a schematic plan view of a display device according to another exemplary embodiment, and fig. 42 is a schematic cross-sectional view of a light emitting diode pixel for a display according to an exemplary embodiment.

Referring to fig. 41, a display apparatus 3000 includes a support substrate 251 and a plurality of pixels 300 disposed on the support substrate 251. Each pixel 300 includes a first sub-pixel R, a second sub-pixel G, and a third sub-pixel B.

Referring to fig. 42, the support substrate 251 supports the LED stacks 323, 333, 343. The support substrate 251 may include a circuit on a surface thereof or in the same without being limited thereto. The support substrate 251 may include, for example, a Si substrate or a Ge substrate.

The first subpixel R comprises a first LED stack 323, the second subpixel G comprises a first LED stack 323 and a second LED stack 333, and the third subpixel B comprises a first LED stack 323, a second LED stack 333 and a third LED stack 343. The first sub-pixel R is adapted to emit light through the first LED stack 323, the second sub-pixel G is adapted to emit light through the second LED stack 333, and the third sub-pixel B is adapted to emit light through the third LED stack 343. The first LED stack 323 of the second subpixel G and the first and second LED stacks 323 and 333 of the third subpixel B may not emit light and thus may be electrically floating. In addition, the first, second, and third sub-pixels R, G, and B may be independently driven.

As shown in the figure, the first subpixel R does not include the second LED stack 333 and the third LED stack 343, and the second subpixel G does not include the third LED stack 343. In this way, light generated from the first LED stack 323 may be emitted to the outside without passing through the second LED stack 33 and the third LED stack 43. In addition, the light generated from the second LED stack 333 may be emitted to the outside without passing through the third LED stack 343.

In the second subpixel G, the first LED stack 323 vertically overlaps the second LED stack 333, and in the third subpixel B, the first LED stack 323, the second LED stack 333, and the third LED stack 343 vertically overlap each other. However, the inventive concept is not limited thereto, and the arrangement order of the sub-pixels may be variously modified.

In addition, the first LED stacks 323 of the first, second, and third sub-pixels R, G, and B may have a stack structure of substantially the same semiconductor layers and may be disposed on substantially the same plane. In addition, the second LED stacks 333 of the second and third subpixels G and B may have a stack structure of substantially the same semiconductor layers and may be disposed on substantially the same plane. Thus, the first, second and third subpixels R, G and B have different numbers of LED stacks 323, 333 and 343 therein and thus have different heights from each other.

Further, the region of the first LED stack 323 of the first subpixel R, the region of the second LED stack 333 of the second subpixel G, and the region of the third LED stack of the third subpixel B may have different areas from each other, and the light emission intensity of light emitted from each of the subpixels R, G, B may be adjusted by adjusting their areas.

Each of the first, second, and third LED stacks 323, 333, 343 includes an n-type semiconductor layer, a p-type semiconductor layer, and an active layer interposed between the n-type and p-type semiconductor layers. The active layer may have a multiple quantum well structure. The first, second, and third LED stacks 323, 333, and 343 may include different active layers to emit light having different wavelengths from one another. For example, the first LED stack 323 may be a red-emitting inorganic light emitting diode, the second LED stack 333 may be a green-emitting inorganic light emitting diode, and the third LED stack 343 may be a blue-emitting inorganic light emitting diode. Specifically, the first LED stack 323 may include an AlGaInP-based well layer, and the second LED stack 333 may include an AlGaInP-based or AlGaInN-based well layer. The third LED stack 343 may include an AlGaInN-based well layer. However, the inventive concept is not limited thereto, and the wavelengths of the light emitted from the first, second, and third LED stacks 323, 333, and 343 may be changed. For example, the first, second, and third LED stacks 323, 333, and 343 may emit green, blue, and red light, respectively, or may emit blue, green, and red light, respectively. As another example, when the light emitting diode pixel includes a micro LED, the first LED stack 323 may emit any one of red, green, and blue light, and the second and third LED stacks 333 and 343 may emit the remaining one of red, green, and blue light, respectively, without adversely affecting operation due to the small form factor of the micro LED.

Fig. 43 is a schematic circuit diagram of a display device according to an exemplary embodiment.

Referring to fig. 43, the display device according to an exemplary embodiment may be implemented to operate in a passive matrix manner. As described with reference to fig. 41 and 42, one pixel includes a first subpixel R, a second subpixel G, and a third subpixel B. The first LED stack 323 of the first subpixel R emits light having a first wavelength, the second LED stack 333 of the second subpixel G emits light having a second wavelength, and the third LED stack 343 of the third subpixel B emits light having a third wavelength. The anode electrode of the first subpixel R, the anode electrode of the second subpixel G, and the anode electrode of the third subpixel B may be connected to a common line, for example, a data line Vdata325, and the cathode electrode of the first subpixel R, the cathode electrode of the second subpixel G, and the cathode electrode of the third subpixel B may be connected to different lines, for example, scan lines Vscan 371, 373, 375.

For example, in the first pixel, the anode of the first subpixel R, the anode of the second subpixel G, and the anode of the third subpixel B are commonly connected to the data line Vdata1, and the cathode of the first subpixel R, the cathode of the second subpixel G, and the cathode of the third subpixel B are connected to the scan lines Vscan1-1, Vscan1-2, Vscan1-3, respectively. Therefore, the sub-pixels R, G, B in the same pixel can be driven individually.

In addition, each of the first, second, and third sub-pixels R, G, and B may be driven by pulse width modulation or by varying the magnitude of current, thereby controlling the brightness of each sub-pixel. Alternatively, the brightness may be adjusted by adjusting the area of the region of the first LED stack 323 of the first subpixel R, the area of the region of the second LED stack 333 of the second subpixel G, and the area of the region of the third LED stack 343 of the third subpixel B. For example, the LED stack (e.g., the first LED stack 323 of the first subpixel R) emitting light having low visibility may be formed to have a larger area than the second LED stack 333 or the third LED stack 343 of the second and third subpixels G and B, and thus, light having higher emission intensity may be emitted at the same current density. In addition, the second and third LED stacks 333 and 343 of the second and third subpixels G and B may be formed to have different areas. In this way, the light emission intensity of light emitted from each of the first, second, and third sub-pixels R, G, and B may be adjusted according to the visibility of light emitted from each of the first, second, and third sub-pixels R, G, and B by adjusting the area of the first LED stack 323, the area of the second LED stack 333, and the area of the third LED stack 343.

Fig. 44 is a schematic plan view of a display apparatus according to an exemplary embodiment. Fig. 45 is an enlarged plan view of one pixel of the display device of fig. 44. Fig. 46A, 46B, 46C and 46D are schematic sectional views taken along line a-a, line B-B, line C-C and line D-D of fig. 45, respectively.

Referring to fig. 44, 45, 46A, 46B, 46C, and 46D, a display device 3000A includes a support substrate 251, a plurality of pixels 300A, a first subpixel R, a second subpixel G, a third subpixel B, a first LED stack 323, a second LED stack 333, a third LED stack 343, a reflective electrode 325 (or a first-2 ohmic electrode), a first-1 ohmic electrode 329, a second-1 ohmic electrode 339, a second-2 ohmic electrode 335, a third-1 ohmic electrode 349, a third-2 ohmic electrode 345, an electrode pad 336, 346, a first bonding layer 353, a second bonding layer 337, a third bonding layer 347, a first insulating layer 361, a first reflective layer 363, a second insulating layer 365, a second reflective layer 367, a lower insulating layer 368, an upper insulating layer 369, interconnection lines 371, 373, 375, and connection portions 371a, 373a, 375a, a, 377a, 377 b.

Each sub-pixel R, G, B is connected to the reflective electrode 325 and interconnect lines 371, 373, 375. As shown in fig. 43, the reflective electrode 325 may correspond to the data line Vdata, and the interconnection lines 371, 373, 375 may correspond to the scan line Vscan.

As shown in fig. 44, the pixels may be arranged in a matrix form in which anodes of the sub-pixels R, G, B in each pixel are commonly connected to the reflective electrode 325, and cathodes of the sub-pixels R, G, B in each pixel are connected to interconnection lines 371, 373, 375 that are isolated from each other. The connection portions 371a, 373a, 375a may connect the interconnection lines 371, 373, 375 to the sub-pixel R, G, B.

The support substrate 251 supports the LED stacks 323, 333, 343. The support substrate 251 may include a circuit on a surface thereof or in the same without being limited thereto. The support substrate 251 may include, for example, a glass substrate, a sapphire substrate, a Si substrate, or a Ge substrate.

The first LED stack 323 includes a first conductive type semiconductor layer 323a and a second conductive type semiconductor layer 323 b. The second LED stack 333 includes a first conductive type semiconductor layer 333a and a second conductive type semiconductor layer 333 b. The third LED stack 343 includes a first conductive type semiconductor layer 343a and a second conductive type semiconductor layer 343 b. In addition, active layers may be interposed between the first and second conductive type semiconductor layers 323a and 323b, 333a and 333b, and 343a and 343b, respectively.

In an exemplary embodiment, each of the first conductive type semiconductor layers 323a, 333a, 343a may be an n-type semiconductor layer, and each of the second conductive type semiconductor layers 323b, 333b, 343b may be a p-type semiconductor layer. In some exemplary embodiments, a roughened surface may be formed on the surface of each of the first conductive type semiconductor layers 323a, 333a, 343a by surface texturing. However, the inventive concept is not so limited and the type of semiconductor in each LED stack may vary.

The first LED stack 323 is disposed adjacent to the support substrate 251. The second LED stack 333 is disposed above the first LED stack 323. The third LED stack 343 is disposed over the second LED stack 333. In addition, in each pixel, the second LED stack 333 is disposed on the first LED stack 323 of the second subpixel G and the first LED stack 323 of the third subpixel B. Further, in each pixel, a third LED stack 343 is disposed on the second LED stack 333 of the third subpixel B.

Accordingly, light generated from the first LED stack 323 of the first subpixel R may be emitted to the outside without passing through the second LED stack 333 and the third LED stack 343. In addition, light generated from the second LED stack 333 of the second subpixel G may be emitted to the outside without passing through the third LED stack 343. In addition, light generated from the third LED stack 343 of the third subpixel B may also be emitted to the outside without passing through the first and second LED stacks 323 and 333.

The materials forming the first, second, and third LED stacks 323, 333, 343 are substantially the same as those described with reference to fig. 42, and thus, a detailed description thereof will be omitted in order to avoid redundancy.

The reflective electrode 325 forms an ohmic contact with a lower surface of the first LED stack 323 (e.g., the second conductive type semiconductor layer 323b thereof). The reflective electrode 325 includes a reflective layer that may reflect light emitted from the first LED stack 323. As shown in the figure, the reflective electrode 325 may cover almost the entire lower surface of the first LED stack. In addition, the reflective electrode 325 may be commonly connected to the plurality of pixels 300a and may correspond to the data line Vdata.

The reflective electrode 325 may be formed of, for example, a material layer forming an ohmic contact with the second conductive type semiconductor layer 323b of the first LED stack 323, and may include a reflective layer that may reflect light (e.g., red light) generated from the first LED stack 323.

The reflective electrode 325 may include an ohmic reflective layer, and may Be formed of, for example, an Au-Zn alloy or an Au-Be alloy. These alloys have high reflectance for light in the red range and form ohmic contact with the second conductive type semiconductor layer 323 b.

The first-1 ohmic electrode 329 forms an ohmic contact with the first conductive type semiconductor layer 323a of the first subpixel R. The first-1 ohmic electrode 329 may include a pad region and an extension portion (see fig. 48A), and as shown in fig. 46B, the connection portion 375a may be connected to the pad region of the first-1 ohmic electrode 329. The first-1 ohmic electrode 329 is omitted on the first LED stack 323 of the second and third subpixels G and B.

The second-1 ohmic electrode 339 forms ohmic contact with the first conductive type semiconductor layer 333a of the second LED stack 333 of the second subpixel G. The second-1 ohmic electrode 339 may also include a pad region and an extension portion (see fig. 52A), and as shown in fig. 46C, the connection portion 373a may be connected to the pad region of the second-1 ohmic electrode 339. The second-1 ohmic electrode 339 may be spaced apart from a region on which the third LED stack 343 is disposed.

The second-2 ohmic electrode 335 forms an ohmic contact with the second conductive type semiconductor layer 333b of the second LED stack 333 of the second subpixel G. The second-2 ohmic electrode 335 may also be disposed under the second conductive type semiconductor layer 333B of the second LED stack 333 of the third subpixel B. The second-2 ohmic electrode 335 may include a reflective layer that may reflect light generated from the second LED stack 333. For example, the second-2 ohmic electrode 335 may include a metal reflective layer.

The electrode pad 336 may be formed on the second-2 ohmic electrode 335. The electrode pad 336 is restrictively disposed on the second-2 ohmic electrode 335, and the connection portion 377b may be connected to the electrode pad 336.

The third-1 ohmic electrode 349 forms an ohmic contact with the first conductive type semiconductor layer 343a of the third LED stack 343. The third-1 ohmic electrode 349 may also include a pad region and an extension portion (see fig. 50A), and as shown in fig. 46D, the connection portion 371a may be connected to the pad region of the third-1 ohmic electrode 349.

The third-2 ohmic electrode 345 forms an ohmic contact with the second conductive type semiconductor layer 343b of the third LED stack 343. The third-2 ohmic electrode 345 may include a reflective layer that may reflect light generated from the third LED stack 333. For example, the third-2 ohmic electrode 345 may include a metal layer.

The electrode pad 346 may be formed on the third-2 ohmic electrode 345. The electrode pad 346 is restrictively disposed on the third-2 ohmic electrode 345. The connection portion 377a may be connected to the electrode pad 346.

The reflective electrode 325, the second-2 ohmic electrode 335, and the third-2 ohmic electrode 345 may assist current spreading by ohmic contact with the p-type semiconductor layer of each of the LED stacks 323, 333, 343. The first-1, second-1, and third-1 ohmic electrodes 329, 339, 349 may assist in current spreading by ohmic contact with the n-type semiconductor layer of each of the LED stacks 323, 333, 343.

The first bonding layer 353 bonds the first LED stack 323 to the support substrate 251. As shown in the figure, the reflective electrode 325 may abut the first bonding layer 353. The first bonding layer 353 may be a light transmissive layer or an opaque layer. The first bonding layer 353 may be formed of an organic or inorganic material. Examples of the organic material may include SU8, poly (methyl methacrylate) (PMMA), polyimide, parylene, benzocyclobutene (BCB), or others, and examples of the inorganic material may include Al₂O₃、SiO₂、SiN_xOr otherwise. The organic material layer may be bonded under high vacuum and high pressure conditions, and the inorganic material layer may be bonded under high vacuum after the surface energy is changed using plasma by, for example, chemical mechanical polishing to planarize the surface of the inorganic material layer.Specifically, a bonding layer formed of a black epoxy resin capable of absorbing light may be used as the first bonding layer 353, which may improve the contrast of the display device. The first bonding layer 353 may also be formed of spin-on glass.

In the second and third sub-pixels G and B, the first reflective layer 363 may be interposed between the first and second LED stacks 323 and 333. The first reflective layer 363 may block light generated from the first LED stack 323 of the first subpixel R and entering the first LED stack 323 of the second subpixel R and the third subpixel B from entering the second LED stack 333 of the second subpixel G and the third subpixel B, thereby preventing light interference between the subpixels.

The first reflective layer 363 may include a metal layer having a high reflectivity to light generated from the first LED stack 323 of the first subpixel R, for example, an Au layer, an Al layer, or an Ag layer.

A second reflective layer 367 is interposed between the second LED stack 333 and the third LED stack 343. The second reflective layer 367 may block light generated in the second LED stack 333 of the second subpixel G and entering the second LED stack 333 of the third subpixel B from entering the third LED stack 343 of the third subpixel B, thereby preventing light interference between the subpixels. In particular, the second reflective layer 367 may include a metal layer having high reflectivity to light generated from the second LED stack 333 of the second subpixel G, such as an Au layer, an Al layer, or an Ag layer.

The first insulating layer 361 is interposed between the first reflective layer 363 and the first LED stack 323. The first insulating layer 361 insulates the first reflective layer 363 from the first LED stack 323. The first insulating layer 361 may include a dielectric layer having a refractive index lower than that of the first LED stack 323, e.g., SiO₂. Accordingly, the first LED stack 323 having a high refractive index, the first insulating layer 361 having a low refractive index, and the first reflective layer 363 are sequentially stacked over one another to form an omni-directional reflector (ODR).

A second insulating layer 365 is interposed between the second reflective layer 367 and the second LED stack 333. The second insulating layer 365 insulates the second reflective layer 367 from the second LED stack 333. The second insulating layer 365 may comprise a dielectric layer having a lower refractive index than the refractive index of the second LED stack 333, for exampleSuch as SiO₂. Accordingly, the second LED stack 333 having a high refractive index, the second insulating layer 365 having a low refractive index, and the second reflective layer 367 are sequentially stacked over one another to form an omni-directional reflector (ODR).

The second bonding layers 337 respectively bond the first LED stack 323 to the second LED stack 333. A second bonding layer 337 may be interposed between the first reflective layer 363 and the second-2 ohmic electrode 335 to bond the first reflective layer 363 to the second-2 ohmic electrode 335. In some exemplary embodiments, the first reflective layer 363 may be omitted. In this case, the second bonding layer 337 may bond the first insulating layer 361 to the second-2 ohmic electrode 335. The second bonding layer 337 may include a metal bonding layer, such as AuSn, without being limited thereto. Alternatively, the second bonding layer 337 may include substantially the same bonding material as the first bonding layer 353.

The third bonding layer 347 bonds the second LED stack 333 to the third LED stack 343. The third bonding layer 347 may be interposed between the second reflective layer 367 and the third-2 ohmic electrode 345 to bond the second reflective layer 367 to the third-2 ohmic electrode 345. In some exemplary embodiments, the second reflective layer 367 may be omitted. In this case, the second reflective layer 367 may bond the second insulating layer 365 to the third-2 ohmic electrode 345. The third bonding layer 347 may include a metal bonding layer, such as AuSn, without being limited thereto. Alternatively, the third bonding layer 347 may include substantially the same bonding material as the first bonding layer 353.

The lower insulating layer 368 may cover the first, second, and third LED stacks 323, 333, 343. The lower insulating layer 368 may abut an upper surface of the first LED stack 323 of the first subpixel R, an upper surface of the second LED stack 333 of the second subpixel G, and an upper surface of the third LED stack 343 of the third subpixel B. In addition, the lower insulating layer 368 covers the reflective electrode 325 exposed around the first LED stack 323. The lower insulating layer 368 may have an opening to provide an electrical connection path.

The upper insulating layer 369 covers the lower insulating layer 368. The upper insulating layer 369 may have openings to provide electrical connection paths.

The lower insulating layer 368 and the upper insulating layer 369 may be formed of any insulating material such as silicon oxide or silicon nitride, without being limited thereto.

As shown in fig. 44 and 45, the interconnection lines 371, 373, 375 may be disposed substantially orthogonal to the reflective electrode 325. The interconnection lines 371, 375 are disposed on the upper insulating layer 369 and may be connected to the third-1 ohmic electrode 349 and the first-1 ohmic electrode 329 through connection portions 371a, 375a, respectively. To this end, the upper and lower insulating layers 369 and 368 may have openings exposing the third-1 ohmic electrodes 349 and the first-1 ohmic electrodes 329.

The interconnection 373 is disposed on the lower insulating layer 368 and insulated from the reflective electrode 325. The interconnection 373 may be disposed between the lower insulating layer 368 and the upper insulating layer 369, and may be connected to the second-1 ohmic electrode 339 through a connection portion 373 a. For this purpose, the lower insulating layer 368 has an opening exposing the second-1 ohmic electrode 339.

The connection portions 377a, 377b are disposed between the lower insulating layer 368 and the upper insulating layer 369, and electrically connect the electrode pads 46, 36 to the reflective electrode 325. For this purpose, the lower insulating layer 368 may have openings exposing the electrode pads 336, 346 and the reflective electrode 325.

The interconnect line 371 and the interconnect line 373 are insulated from each other by the upper insulating layer 369, and thus, may be disposed to overlap each other in the vertical direction.

Although the electrode of each pixel is described as being connected to the data line and the scan line, the interconnection lines 371 and 375 are described as being formed on the lower insulating layer 368, and the interconnection line 373 is described as being disposed between the lower insulating layer 368 and the upper insulating layer 369, the inventive concept is not limited thereto. For example, all the interconnect lines 371, 373, 375 may be formed on the lower insulating layer 368 and may be covered by the upper insulating layer 81, and the connection portions 371a, 375a may be formed on the upper insulating layer 369.

Next, a method of manufacturing the display device 3000A according to an exemplary embodiment will be described below.

Fig. 47 to 59 are schematic plan and sectional views illustrating a method of manufacturing a display apparatus according to an exemplary embodiment of the present disclosure. Each cross-sectional view is taken along line a-a of the respective plan view.

First, referring to fig. 47A, a first LED stack 323 is grown on a first substrate 321. The first substrate 321 may be, for example, a GaAs substrate. The first LED stack 323 may be formed of AlGaInP-based semiconductor layers, and includes a first conductive type semiconductor layer 323a, an active layer, and a second conductive type semiconductor layer 323 b.

Then, a reflective electrode 325 is formed on the first LED stack 323. The reflective electrode 325 may Be formed of, for example, an Au-Zn alloy or an Au-Be alloy.

The reflective electrode 325 may be formed by a lift-off process or the like, and may be subjected to patterning to have a specific shape. For example, the reflective electrode 325 may be subjected to patterning to have a length connecting a plurality of pixels. However, the inventive concept is not limited thereto. Alternatively, the reflective electrode 325 may be formed over the entire upper surface of the first LED stack 323 without patterning, or may be subjected to patterning after being formed thereon.

The reflective electrode 325 may form an ohmic contact with the second conductive type semiconductor layer 323b (e.g., p-type semiconductor layer) of the first LED stack 323.

Referring to fig. 47B, a second LED stack 333 is grown on the second substrate 331, and a second-2 ohmic electrode 335 is formed on the second LED stack 333. The second LED stack 333 may be formed of an AlGaInP or AlGaInN based semiconductor layer, and may include an AlGaInP or AlGaInN based well layer. The second substrate 331 may be a substrate (e.g., GaAs substrate) on which an AlGaInP-based semiconductor layer can be grown, or a substrate (e.g., sapphire substrate) on which a GaN-based semiconductor layer can be grown. For example, the composition of Al, Ga, and In the second LED stack 333 may be determined such that the second LED stack 333 may emit green light. The second-2 ohmic electrode 335 forms an ohmic contact with the second conductive type semiconductor layer 333b (e.g., p-type semiconductor layer) of the second LED stack 333. The second-2 ohmic electrode 335 may include a reflective layer that may reflect light generated from the second LED stack 333.

A bonding material layer 337a may be formed on the second-2 ohmic electrode 335. The bonding material layer 337a may include a metal layer, such as AuSn, without being limited thereto.

Referring to fig. 47C, a third LED stack 343 is grown on the third substrate 341, and a third-2 ohmic electrode 345 is formed on the third LED stack 343. The third LED stack 343 may be formed of AlGaInN-based semiconductor layers and may include a first conductive type semiconductor layer 343a, an active layer, and a second conductive type semiconductor layer 343 b. The third substrate 341 is a substrate on which a GaN-based semiconductor layer can be grown, and may be different from the first substrate 321. For example, the composition of Al, Ga, and In the third LED stack 343 may be determined such that the third LED stack 343 may emit blue light. The third-2 ohmic electrode 345 forms an ohmic contact with the second conductive type semiconductor layer 343b (e.g., p-type semiconductor layer) of the third LED stack 343. The third-2 ohmic electrode 345 may include a reflective layer that may reflect light generated from the third LED stack 343.

A bonding material layer 347a may be formed on the third-2 ohmic electrode 345. The bonding material layer 347a may include a metal layer, such as AuSn, without being limited thereto.

Since the first, second, and third LED stacks 323, 333, and 343 are grown on different substrates, respectively, the order of forming the first to third LED stacks is not particularly limited.

Referring to fig. 48A and 48B, the first LED stack 323 of fig. 47A is bonded to the upper side of the support substrate 251 via the first bonding layer 353. The reflective electrode 325 may be disposed to face the support substrate 251 and may be bonded to the first bonding layer 353. The first substrate 321 is removed from the first LED stack 323 by chemical etching or the like. Thus, the upper surface of the first conductive type semiconductor layer 323a of the first LED stack 323 is exposed. In some exemplary embodiments, a roughened surface may be formed on the exposed surface of the first conductive type semiconductor layer 323a by surface texturing or the like.

A first-1 ohmic electrode 329 is then formed on the exposed surface of the first LED stack 323. The ohmic electrode 329 may be formed of, for example, an Au-Te alloy or an Au-Ge alloy. An ohmic electrode 329 may be formed in each pixel region. The ohmic electrode 329 may be formed toward one side in each pixel region. As shown in the drawing, the ohmic electrode 329 may include a pad region and an extension portion. As shown in the drawing, the extension portion may extend substantially in the longitudinal direction of the reflective electrode 325.

Referring to fig. 49A and 49B, a first insulating layer 361 is formed on the first LED stack 323, and then, a first reflective layer 363 is formed on the first insulating layer 361. As shown in the drawing, the first insulating layer 361 may be formed to cover the first-1 ohmic electrode 329, and the first reflective layer 363 may not cover the first-1 ohmic electrode 329. However, the inventive concept is not limited thereto. For example, the first reflective layer 363 may cover the first-1 ohmic electrode 329. In some exemplary embodiments, the first reflective layer 363 may be omitted.

A bonding material layer 337b is formed on the first reflective layer 363. The second LED stack 333 of fig. 47B is bonded to the upper side of the bonding material layer 337B. When the first reflective layer 363 is omitted, the bonding material layer 337b may be formed on the first insulating layer 361. The bonding material layer 337a is disposed to face the support substrate 251 and is bonded to the bonding material layer 337a to form a second bonding layer 337, and the first LED stack 323 is bonded to the second LED stack 333 through the second bonding layer 337.

The second substrate 331 is removed from the second LED stack 333 by laser lift-off or chemical lift-off. In this way, the upper surface of the first conductive type semiconductor layer 333a of the second LED stack 333 is exposed. In some exemplary embodiments, a roughened surface may be formed on the exposed surface of the first conductive type semiconductor layer 333a by surface texturing or the like.

Referring to fig. 50A and 50B, first, a second insulating layer 365 is formed on the second LED stack 333, and then, a second reflective layer 367 is formed on the second insulating layer 365. Thereafter, a bonding material layer 347B is formed on the second reflective layer 367, and the second LED stack 333 of fig. 48B is bonded to the upper side of the bonding material layer 347B. In some exemplary embodiments, the second reflective layer 367 may be omitted. The bonding material layer 347a is disposed to face the support substrate 251 and is bonded to the bonding material layer 347a to form a third bonding layer 347, and the second LED stack 333 is bonded to the third LED stack 343 through the third bonding layer 347.

The third substrate 341 may be removed from the third LED stack 343 by laser lift-off or chemical lift-off. In this way, the upper surface of the first conductive type semiconductor layer 343a of the third LED stack 343 is exposed. In some exemplary embodiments, a roughened surface may be formed on the exposed surface of the first conductive type semiconductor layer 343a by surface texturing or the like.

Next, a third-1 ohmic electrode 349 is formed on the first conductive type semiconductor layer 343 a. The third-1 ohmic electrode 349 may be formed toward the other side of the pixel to be opposite to the first-1 ohmic electrode 329. The third-1 ohmic electrode 349 may include a pad region and an extension portion. The extended portion may extend substantially in the longitudinal direction of the reflective electrode 325.

Referring to fig. 51A and 51B, in each pixel region, the third LED stack 343 is removed by patterning the third LED stack 343 except for a region corresponding to the third subpixel B. Thus, as shown in the drawing, the third-2 ohmic electrode 345 is exposed. In addition, in the region of the third subpixel B, a depression (indentation) may be formed on the third LED stack 343.

An electrode pad 346 may be formed on the third-2 ohmic electrode 345 exposed by the recess formed in the third subpixel B. Although the third-2 ohmic electrode 345 and the electrode pad 346 are described as being formed through separate processes in the illustrated exemplary embodiment, in other exemplary embodiments, the third-2 ohmic electrode 345 and the electrode pad 346 may be formed together through the same process. For example, after the third-2 ohmic electrode 345 is exposed, the third-1 ohmic electrode 349 and the electrode pad 346 may be formed together by a lift-off process or the like.

Referring to fig. 52A and 52B, in each pixel region, the third-2 ohmic electrode 345, the third bonding layer 347, the second reflective layer 367, and the second transparent insulating layer 365 are sequentially subjected to patterning to expose the second LED stack 333. The third-2 ohmic electrode 345 is restrictively disposed to be adjacent to the region of the third sub-pixel B.

In each pixel region, a second-1 ohmic electrode 339 is formed on the second LED stack 333. As shown in fig. 52A, the second-1 ohmic electrode 339 may include a pad region and an extension portion. The extended portion may extend substantially in the longitudinal direction of the reflective electrode 325. The second-1 ohmic electrode 339 forms ohmic contact with the first conductive type semiconductor layer 333 a. As shown in the drawing, the second-1 ohmic electrode 339 may be disposed between the first-1 ohmic electrode 329 and the third-1 ohmic electrode 349, without being limited thereto.

Referring to fig. 53A and 53B, in each pixel, the second LED stack 333 is removed by patterning the second LED stack 333 except for regions corresponding to the third sub-pixel B and the second sub-pixel G. The second LED stack 333 in the area of the second sub-pixel G is isolated from the second LED stack 333 in the area of the third sub-pixel B.

Because the second LED stack 333 is subjected to patterning, the second-2 ohmic electrode 335 is exposed. The second LED stack 333 in the region of the second subpixel G may include a recess into which the electrode pad 336 may be formed on the second-2 ohmic electrode 335.

Although the second-1 ohmic electrode 339 and the electrode pad 336 are described as being formed through separate processes in the illustrated exemplary embodiment, the second-1 ohmic electrode 339 and the electrode pad 336 may be formed together through the same process in other exemplary embodiments. For example, after the second-2 ohmic electrode 335 is exposed, the second-1 ohmic electrode 339 and the electrode pad 336 may be formed together by a lift-off process or the like.

Referring to fig. 54A and 54B, the second-2 ohmic electrode 335, the second bonding layer 337, the first reflective layer 363, and the first transparent insulating layer 361 are sequentially subjected to patterning to expose the first LED stack 323. As shown in fig. 54A, the second-2 ohmic electrode 335 is restrictively disposed to be close to the area of the second subpixel G.

In each pixel region, the first-1 ohmic electrode 329 formed on the first LED stack 323 is exposed. As shown in fig. 54A, the first-1 ohmic electrode 329 may include a pad region and an extension portion. The extended portion may extend substantially in the longitudinal direction of the reflective electrode 325.

Referring to fig. 55A and 55B, the first LED stack 323 is removed by patterning the first LED stack 323 from an area excluding areas corresponding to the first, second, and third sub-pixels R, G, and B. The first-1 ohmic electrode 329 remains in the region of the first subpixel R. The first LED stack 323 in the region of the first subpixel R is isolated from the first LED stack 323 in the region of the second subpixel G and the first LED stack 323 in the region of the third subpixel B. The first LED stack 323 in the region of the second subpixel G may be isolated from the first LED stack 323 in the region of the third subpixel B, but is not limited thereto. For example, the first LED stack 323 of the second subpixel G may continuously extend to the third subpixel B.

Since the first LED stack 323 is subjected to patterning, the reflective electrode 325 is exposed, and a surface of the first bonding layer 353 may be partially exposed. In other exemplary embodiments, an insulating layer may be disposed on the first bonding layer 353. In this case, the insulating layer is exposed, and the surface of the first bonding layer 353 may not be exposed.

Referring to fig. 56A and 56B, a lower insulating layer 368 is formed. The lower insulating layer 368 may cover the first LED stack 323, the second LED stack 333, the third LED stack 343, the reflective electrode 325, and the first bonding layer 353. The lower insulating layer 368 may be subjected to patterning to form openings exposing the first-1 ohmic electrode 329, the second-1 ohmic electrode 339, the third-1 ohmic electrode 349, the electrode pads 336 and 346, and the reflective electrode 325.

Referring to fig. 57, an interconnection line 373 and connection portions 373a, 377b are formed on the lower insulating layer 368. The connection portion 373a connects the second-1 ohmic electrode 339 to the interconnection line 373, the connection portion 377a connects the electrode pad 346 to the reflective electrode 325, and the connection portion 377b connects the electrode pad 336 to the reflective electrode 325. A sectional view taken along line a-a of fig. 57 is substantially the same as fig. 56B, and therefore, it is omitted to avoid redundancy.

Referring to fig. 58A and 58B, an upper insulating layer 369 is formed. The upper insulating layer 369 covers the interconnect 373 and the connection portions 373a, 377 b. The upper insulating layer 369 may be subjected to patterning to expose pad regions of the first-1 ohmic electrode 329 and the third-1 ohmic electrode 349.

Referring to fig. 59, interconnection lines 371, 375 and connection portions 371a, 375a are formed on the upper insulating layer 369. The connection portion 371a connects the interconnection line 371 to the third-1 ohmic electrode 349, and the connection portion 375a connects the interconnection line 375 to the first-1 ohmic electrode 329.

Thus, the display device 3000A of fig. 44 and 45 is provided. A sectional view taken along line a-a of fig. 59 is substantially the same as fig. 58B, and therefore, it is omitted to avoid redundancy.

In the exemplary embodiment shown, optical interference may occur between the sub-pixels R, G, B. More specifically, optical interference may occur between the first, second, and third LED stacks 323, 333, 343. Accordingly, a light blocking layer, such as a light reflecting layer or a light absorbing layer, may be formed on a side surface of each sub-pixel to prevent light interference. The light reflection layer may include a distributed bragg reflector that may be formed by alternately stacking material layers having different refractive indexes or by forming a metal reflection layer on a transparent insulation layer or including a reflective material (e.g., TiO)₂) And a white organic material. The light absorbing layer may comprise, for example, a black epoxy.

For example, at least one of the lower insulating layer 368 and the upper insulating layer 369 may include a light reflecting layer or a light absorbing layer. In this case, the lower insulating layer 368 and/or the upper insulating layer 369 may have openings on the first, second, and third LED stacks 323, 333, and 343 to allow light generated from each sub-pixel to be emitted to the outside therethrough. An opening through which light is emitted to the outside may be restrictively formed in an upper region of each of the first, second, and third LED stacks 323, 333, and 343. In this way, the edges of the first LED stack 323, the second LED stack 333, and the third LED stack 343 may also be covered by the reflective layer.

Although the pixels are described as being driven in a passive matrix manner, the inventive concept is not limited thereto, and the pixels may be driven in an active matrix manner in some exemplary embodiments.

Fig. 60 is a schematic cross-sectional view of a display apparatus according to another exemplary embodiment.

Although the reflective electrode 325 is directly formed on the second conductive type semiconductor layer 323b in fig. 47A, the inventive concept is not limited thereto. For example, referring to fig. 60, the reflective electrode 325 may include an ohmic contact layer 325a and a reflective layer 325 b. The ohmic contact layer 325a may Be formed of, for example, an Au-Zn alloy or an Au-Be alloy, and the reflective layer 325b may Be formed of Al, Ag, or Au. In particular, when the reflective layer 325b is formed of Au, the reflective layer 325b may exhibit a relatively high reflectance to light (e.g., red light) generated from the first LED stack 323, and may exhibit a relatively low reflectance to light (e.g., green or blue light) generated from the second and third LED stacks 333 and 343.

The insulating layer 327 may be disposed between the reflective layer 325b and the second conductive type semiconductor layer 323 b. The insulating layer 327 may have an opening exposing the second conductive type semiconductor layer 323b, and the ohmic contact layer 325a may be formed in the opening of the insulating layer 327.

Since the reflective layer 325b covers the insulating layer 327, an omni-directional reflector (ODR) may be formed by a stacked structure of the first LED stack 323 having a high refractive index, the insulating layer 327 having a low refractive index, and the reflective layer 325 b.

The reflective electrode 325 may be formed by the following process. First, a first LED stack 323 is grown on a substrate 321, and an insulating layer 327 is formed on the first LED stack 323. Then, an opening is formed by patterning the insulating layer 327. For example, SiO may be formed on the first LED stack 323₂And a photoresist is deposited thereon, followed by photolithography and development to form a photoresist pattern. Thereafter, SiO is patterned by a photoresist pattern as an etching mask₂The layer is subjected to patterning, thereby forming an insulating layer 327 having an opening.

Thereafter, an ohmic contact layer 325a is formed in the opening of the insulating layer 327. The ohmic contact layer 325a may be formed by a lift-off process or the like. After the ohmic contact layer 325a is formed, a reflective layer 325b is formed to cover the ohmic contact layer 325a and the insulating layer 327. The reflective layer 325b may be formed by a lift-off process or the like. As shown in the figure, the reflective layer 325b may partially or completely cover the ohmic contact layer 325 a. The reflective electrode 325 is formed of an ohmic contact layer 325a and a reflective layer 325 b. The shape of the reflective electrode 325 is substantially the same as that of the reflective electrode described above, and thus, a detailed description thereof will be omitted.

Although the first LED stack 323 is described as being formed of AlGaInP-based semiconductor layers to emit red light, the inventive concept is not limited thereto. For example, the first LED stack 323 may emit green or blue light. Thus, the first LED stack 323 may be formed of an AlGaInN-based semiconductor layer. In addition, the second LED stack 333 or the third LED stack 343 may be formed of an AlGaInP-based semiconductor layer.

According to exemplary embodiments of the present disclosure, a plurality of pixels may be formed at a wafer level by wafer bonding, thereby eliminating the need to separately mount light emitting diodes.

While certain exemplary embodiments and implementations have been described herein, other embodiments and modifications will be apparent from this description. The inventive concept is therefore not limited to such embodiments, but is to be accorded the widest scope consistent with the following claims and with various obvious modifications and equivalent arrangements, as will be apparent to those skilled in the art.