阅读说明：本技术 小发散角N型共阴极Micro LED器件及其阵列 (Small-divergence-angle N-type common-cathode Micro LED device and array thereof ) 是由 孙雷 张婧姣 于 2020-05-27 设计创作，主要内容包括：本发明提供了小发散角N型共阴极Micro LED器件及其阵列,包括微光学系统、绝缘隔离结构、隔离结构、像素电极、N型半导体、量子阱层、P型半导体。由于LED发光原理因素,Micro LED器件出光发散角过大,而在工业曝光领域和图像投影领域受投影镜头数值孔径限制,需要Micro LED器件及其阵列所发出的光具有较小的发散角。本专利通过在Micro LED器件上集成绝缘隔离结构、隔离结构、微光学系统的方式进一步收敛发散角使之满足工业曝光领域和图像投影领域的应用。其中Micro LED上的N型半导体相互连接,形成共阴极结构,有利于进一步简化工艺流程降低生产成本。凭借高集成度和可控的光场发散角度,最终将Micro LED推向工业曝光领域和图像投影领域的大规模应用阶段。(The invention provides an N-type common cathode Micro LED device with a small divergence angle and an array thereof. Due to the LED light-emitting principle, the Micro LED device has an excessively large light-emitting divergence angle, and the light emitted by the Micro LED device and the array thereof needs to have a smaller divergence angle due to the limitation of the numerical aperture of the projection lens in the industrial exposure field and the image projection field. The Micro LED device further converges the divergence angle by integrating an insulating isolation structure, an isolation structure and a Micro optical system on the Micro LED device, so that the Micro LED device meets the application requirements of the industrial exposure field and the image projection field. N-type semiconductors on the Micro LED are connected with one another to form a common cathode structure, so that the process flow is further simplified, and the production cost is reduced. By means of high integration and controllable light field divergence angles, Micro LEDs are finally pushed to the large-scale application stage in the industrial exposure field and the image projection field.)

1. A small-divergence-angle N-type common-cathode Micro LED device is characterized in that: the Micro LED comprises a Micro optical system 1, an insulating isolation structure 2, an isolation structure 3, a pixel electrode 4, an N-type semiconductor 5, a quantum well layer 6 and a P-type semiconductor 7, wherein the N-type semiconductor 5, the quantum well layer 6 and the P-type semiconductor 7 form Micro LED particles; the pixel electrode 4 is positioned at the bottom; the P-type semiconductor 7 is arranged above the pixel electrode 4; the quantum well layer 6 is arranged above the type semiconductor 7; the N-type semiconductor 5 is arranged above the quantum well layer 6; the micro-optical system 1 is arranged above the N-type semiconductor 5; the N-type semiconductor 5 is connected with other adjacent N-type semiconductors 5 of the Micro LED device with the small divergence angle and is finally connected to an external cathode electrode; the insulating isolation structure 2 is adjacent to the pixel electrode 4, the N-type semiconductor 5, the quantum well layer 6 and the P-type semiconductor 7; the isolation structure 3 is adjacent to the micro-optical system 1 and the N-type semiconductor 5.

2. The small divergence angle N-type common cathode Micro LED device of claim 1,

the micro optical system 1 is a transmission type optical system, can transmit the light emitted by the quantum well layer 6, and has a transmittance of 80% or more; the aperture of the micro optical system 1 is less than or equal to 500 micrometers; the micro-optical system 1 is a combination of one or more lenses that function to converge the divergence angle of the light emitted by the quantum well layer 6.

3. The small divergence angle N-type common cathode Micro LED device of claim 1,

the insulating isolation structure 2 is any one or combination of a space filled with air, an insulating material filling layer and an insulating film layer; the insulating isolation structure 2 enables each adjacent quantum well layer 6 and P-type semiconductor 7 in the small-divergence-angle N-type common-cathode Micro LED array to be isolated from each other to form a discrete device.

4. The small divergence angle N-type common cathode Micro LED device of claim 1,

the isolation structure 3 is made of a material having an absorptivity of light emitted from the quantum well layer 6 of more than 70% or a material having a reflectivity of light emitted from the quantum well layer 6 of more than 70%.

5. The small divergence angle N-type common cathode Micro LED device of claim 1,

the pixel electrode 4 is specifically a metal electrode and is connected with an external circuit; the pixel electrode 4 is driven by a CMOS circuit on a silicon substrate or a glass substrate to realize an independent switch and independently supply power to the P-type semiconductor 7.

6. The small divergence angle N-type common cathode Micro LED device of claim 1,

the N-type semiconductor 5 is a group v element doped semiconductor material layer.

7. The small divergence angle N-type common cathode Micro LED device of claim 1,

the quantum well layer 6 is a material layer with a quantum well with electroluminescent characteristics; the light-emitting wavelength range is 170 nm-800 nm.

8. The small divergence angle N-type common cathode Micro LED device of claim 1,

the P-type semiconductor 7 is a semiconductor material layer doped with group III elements or a semiconductor material layer not doped with group III elements.

9. A Micro LED array comprising the small divergence angle N-type common cathode Micro LED device of any one of claims 1-6.

10. A small divergence angle N-type common cathode Micro LED array comprising any number of arrays of small divergence angle N-type common cathode Micro LED devices of any one of claims 1-8.

Technical Field

The invention relates to a small-divergence-angle N-type common-cathode Micro LED device and an array thereof.

Background

Micro LED technology generally refers to a technology in which Micro LED particles are powered by controllable electrodes and control their switches. The current Micro LEDs range in size from the micron level up to the hundred micron level. The relatively large LED particles are generally called Mini LEDs, but the distinction between Mini LEDs and Micro LEDs is relatively blurred. The Micro LED of this patent contains the little LED granule of diameter less than or equal to 500 microns. The Mini LED also contains micro LED particles below 500 microns in some investigator definitions. In the overlapping region defined by the Micro LED and the Mini LED, the Micro LED can also be named by the name of the Mini LED. That is, it is also understood that Micro LEDs described herein may be equivalently replaced with Mini LEDs.

At present, Micro LED technology is widely applied to the field of flat panel display and is rapidly developed. From the aspect of application, the flat panel display field requires a larger viewing angle, and thus requires a larger light emitting angle of the Micro LED. From the technical principle, the electroluminescence of the quantum well layer of the Micro LED is 360-degree luminescence, so that the Micro LED has a great divergence angle, and the application requirement in the field of flat panel display is just met.

When the Micro LED technology is applied to optical applications such as ultraviolet exposure and projectors, due to the introduction of a projection lens, i.e., the limitation of an optical principle, and the requirement of the application on the divergence angle of the emergent light of the projection lens, it is necessary that the light emitted by each pixel unit device of the Micro LED array has a smaller divergence angle corresponding to the projection lens. Light beyond the divergence angle becomes stray light, which causes problems of reduced contrast, excessively high black field brightness, pixel crosstalk, and the like.

According to the invention, by adopting a chip-level optical design and an integrated chip optical processing method, a physical structure for reflecting and absorbing emergent rays is formed through the pixel electrode, the insulating isolation structure and the isolation structure, and finally, the main energy of the emergent rays is emergent towards the cathode electrode and the micro optical system. The Micro optical system further converges the divergence angle of the emergent ray, and finally meets the technical requirement of small divergence angle of the Micro LED device in the field of digital exposure and projection.

In a traditional Micro LED processing method, an N-type semiconductor layer of a large number of Micro LED particles is connected with a transparent cathode electrode or an open cathode electrode, and a common cathode structure is realized through the connection of the cathode electrode. Under the process condition, the transparent cathode electrode still has a certain absorption effect on the emergent light of the Micro LED, and the open cathode electrode also has a certain absorption effect on the emergent light due to the limitation of the opening ratio.

As an improvement of the method, the invention is based on the principle that the N-type semiconductor material in the Micro LED also has higher electron mobility, and the N-type semiconductor in the Micro LED array is made to be a common cathode structure in a mode that the N-type semiconductor layer in the LED epitaxial wafer is not completely separated, so that the cathode electrode does not need to be re-manufactured for all Micro LED particles. The problem of the Micro LED light efficiency that adopts transparent cathode material and opening cathode material to lead to descends is solved. And the light emitting efficiency of the Micro LED particles is further improved.

The Micro LED device with the small divergence angle and the Micro LED array have the main advantages that:

1. the optical structure formed by the insulating isolation structure, the isolation structure and the metal pixel electrode is adopted to reflect light rays emitted by the quantum well layer of the Micro LED particles to the required output direction, so that the overall light efficiency of the whole Micro LED device is further improved.

2. The divergence angle of light emitted by the Micro LED device is further converged to the required divergence angle by adopting the Micro optical system, so that the optical requirement of the digital exposure and image projection system on the Micro LED device with the small divergence angle is met.

3. By replacing the separately fabricated cathode electrode with an N-type semiconductor material layer of Micro LED particles, the structure is further simplified and the cost is reduced.

Disclosure of Invention

The invention provides a small-divergence-angle N-type common-cathode Micro LED device and an array thereof, aiming at enabling the Micro LED device and the Micro LED array to emit light rays with small divergence angles so as to meet the optical requirements of a digital exposure and graphic projection system. Meanwhile, the continuous Micro LED N-type semiconductor layer is used as a common cathode electrode to replace a separately manufactured cathode electrode, so that the light emitting efficiency is further improved, and the manufacturing cost is reduced.

The micro-optical system, the insulating isolation structure, the pixel electrode, the N-type semiconductor, the quantum well layer and the P-type semiconductor are adopted, so that the technical defects in the prior art are overcome.

In order to achieve the purpose, the technical scheme of the invention is realized as follows:

the invention provides an N-type common cathode Micro LED device with a small divergence angle, which comprises a Micro optical system 1, an insulating isolation structure 2, an isolation structure 3, a pixel electrode 4, an N-type semiconductor 5, a quantum well layer 6 and a P-type semiconductor 7, wherein the N-type semiconductor 5, the quantum well layer 6 and the P-type semiconductor 7 form Micro LED particles; the pixel electrode 4 is positioned at the bottom; the P-type semiconductor 7 is arranged above the pixel electrode 4; the quantum well layer 6 is arranged above the type semiconductor 7; the N-type semiconductor 5 is arranged above the quantum well layer 6; the micro-optical system 1 is arranged above the N-type semiconductor 5; the N-type semiconductor 5 is connected with other adjacent N-type semiconductors 5 of the Micro LED device with the small divergence angle and is finally connected to an external cathode electrode; the insulating isolation structure 2 is adjacent to the pixel electrode 4, the N-type semiconductor 5, the quantum well layer 6 and the P-type semiconductor 7; the isolation structure 3 is adjacent to the micro-optical system 1 and the N-type semiconductor 5.

Preferably, the micro optical system 1 is a transmissive optical system, which can transmit light emitted from the quantum well layer 6, and has a transmittance of 80% or more; the aperture of the micro optical system 1 is less than or equal to 500 micrometers; the micro-optical system 1 is a combination of one or more lenses that function to converge the divergence angle of the light emitted by the quantum well layer 6.

Preferably, the insulating isolation structure 2 is any one or combination of a space filled with air, an insulating material filling and an insulating film layer; the insulating isolation structure 2 enables each adjacent quantum well layer 6 and P-type semiconductor 7 in the small-divergence-angle N-type common-cathode Micro LED array to be isolated from each other to form a discrete device.

Preferably, the isolation structure 3 is made of any one of a material having an absorptivity of light emitted from the quantum well layer 6 of more than 70% and a material having a reflectivity of light emitted from the quantum well layer 6 of more than 70%. The isolation structure 3 is spatially in a trench after the N-type semiconductor 5 is etched or on the upper surface of the N-type semiconductor 5.

Preferably, the pixel electrode 4 is a metal electrode and is connected to an external circuit; the pixel electrode 4 is driven by a CMOS circuit on a silicon substrate or a glass substrate to realize an independent switch and independently supply power to the P-type semiconductor 7; the pixel electrode can reflect light rays emitted by the Micro LED particles 2; the pixel electrode 4 is a pixel electrode unit of an independent pixel electrode integrated circuit with mass matrix distribution.

Preferably, the N-type semiconductor 5 is a group v element-doped semiconductor material layer.

Preferably, the quantum well layer 6 is a material layer having a quantum well with electroluminescent characteristics; the light-emitting wavelength range is 170 nm-800 nm.

Preferably, the P-type semiconductor 7 is a group iii element doped semiconductor material layer or an undoped semiconductor material layer.

The invention also provides a small-divergence-angle N-type common-cathode Micro LED array which comprises the small-divergence-angle N-type common-cathode Micro LED device provided by the invention.

The invention also provides a small-divergence-angle N-type common-cathode Micro LED array, which comprises any number of arrays formed by the small-divergence-angle N-type common-cathode Micro LED devices provided by the invention.

The invention is not described in detail by the known technologies in other fields adopted by the invention.

Drawings

FIG. 1 is a schematic structural diagram of a small divergence angle N-type common cathode Micro LED device according to the present invention;

in the figure, a micro optical system 1, an insulating isolation structure 2, an isolation structure 3, a pixel electrode 4, an N-type semiconductor 5, a quantum well layer 6 and a P-type semiconductor 7.

FIG. 2 is a schematic structural diagram of different positions of an isolation structure in the small divergence angle N-type common cathode Micro LED device according to the present invention; wherein fig. 2A is a schematic structural view of the isolation structure 3 at a position above the N-type semiconductor 5, fig. 2B is a schematic structural view of a portion of the isolation structure 3 at a shallow trench position of the N-type semiconductor 5, and fig. 2C is a schematic structural view of the isolation structure 3 at a shallow trench position of the N-type semiconductor 5;

in the figure, a micro optical system 1, an insulating isolation structure 2, an isolation structure 3, a pixel electrode 4, an N-type semiconductor 5, a quantum well layer 6 and a P-type semiconductor 7.

FIG. 3 is a schematic structural diagram of a small divergence angle N-type common cathode Micro LED array according to the present invention;

in the figure, a micro optical system 1, an insulating isolation structure 2, an isolation structure 3, a pixel electrode 4, an N-type semiconductor 5, a quantum well layer 6 and a P-type semiconductor 7.

Detailed Description

Preferably, the isolation structures 3 can be made of one of light reflecting material or light absorbing material.

When a light reflecting material is used, the isolation structures 3 are preferably made of a material having a reflectivity of more than 70% for light emitted from the quantum well layers 6. Further preferably, the isolation structure 3 uses an aluminum film as the reflective material, and the thickness of the aluminum film is in a range of 3 nm to 20 nm.

When a light absorbing material is used, the isolation structures 3 are preferably made of a material that has an absorption of more than 70% of the light emitted by the quantum well layers 6. Further preferably, the isolation structure 3 adopts aluminum oxide (AlO) with a surface nano structure as a light absorption material, and the thickness of the aluminum film layer ranges from 10 nm to 200 nm.

The present invention is further described in detail below with reference to specific examples so that those skilled in the art can practice the invention with reference to the description.

It is to be understood that terms such as "having," "including," and "comprising," as used herein, do not preclude the presence or addition of one or more other terms

The presence or addition of a single other element or combination thereof.

Example 1: small-divergence-angle N-type common-cathode Micro LED device for ultraviolet digital exposure and array thereof

The small-divergence-angle N-type common-cathode Micro LED device provided in this embodiment 1 includes a Micro optical system 1, an insulating isolation structure 2, an isolation structure 3, a pixel electrode 4, an N-type semiconductor 5, a quantum well layer 6, and a P-type semiconductor 7. It should be particularly noted that the isolation structure 3 is made of a light absorbing material and has an absorption effect on light emitted by the quantum well layer 6, so that large-angle stray light is finally absorbed, and the beam quality is further improved.

Preferably, the micro optical system 1 is a single-lens plano-convex lens.

Preferably, the insulating isolation structures 2 are filled with aluminum oxide (AlO).

Preferably, the isolation structure 3 is an aluminum oxide (AlO) thin film with a thickness of 10 nm.

Further preferably, the upper surface of the N-type semiconductor 5 is a complete plane, and the isolation structure 3 is located on the upper surface of the N-type semiconductor 5.

Preferably, the pixel electrode 4 is a gold (Au) electrode, and the pixel electrode 4 and the P-type semiconductor 7 are connected by means of metal bonding.

Preferably, the N-type semiconductor 5 is a group v element doped gallium nitride semiconductor material layer.

Preferably, the quantum well layer 6 is a semiconductor material layer of an Al-In-Ga-N system having a quantum well structure.

Preferably, the P-type semiconductor 7 is a group iii doped gallium nitride semiconductor material layer.

FIG. 3 is a schematic structural plane view of a small divergence angle N-type common cathode Micro LED array according to the present invention; and (3) repeatedly arraying the small-divergence-angle N-type common-cathode Micro LED device shown in the figure 1 to obtain the small-divergence-angle N-type common-cathode Micro LED array.