阅读说明：本技术 一种Mini LED芯片及其制造方法 (Mini LED chip and manufacturing method thereof ) 是由 郑高林 吴永胜 张帆 于 2021-09-08 设计创作，主要内容包括：本发明公开了一种Mini LED芯片及其制造方法,在衬底上制备锥状图形化介质膜,在图形化介质膜远离所述衬底的一端生长外延层；对外延层进行切割道刻蚀后,蚀刻所述切割道侧壁和底部露出的所述图形化介质膜,由于图形化介质膜为锥状的,因此在图形化介质膜位置能够形成正梯形的切割道下侧壁；对切割道侧壁进行腐蚀,能够形成比较粗糙的侧壁表面,从而采用侧面粗化的方式增加光从芯片侧面提取的效率,提高了芯片整体亮度,增加了侧面出射光的占比,使得芯片发光角增大；在上述制得的芯片的上方覆盖绝缘钝化层和反射层,能够在保护芯片侧壁的同时,实现Mini LED芯片的大发光角度的要求。(The invention discloses a Mini LED chip and a manufacturing method thereof.A tapered graphical dielectric film is prepared on a substrate, and an epitaxial layer grows at one end of the graphical dielectric film, which is far away from the substrate; etching the side wall of the cutting channel and the patterned dielectric film exposed at the bottom after etching the cutting channel of the epitaxial layer, wherein the lower side wall of the cutting channel in a regular trapezoid shape can be formed at the position of the patterned dielectric film because the patterned dielectric film is in a conical shape; the side wall of the cutting channel is corroded to form a rough side wall surface, so that the efficiency of extracting light from the side surface of the chip is improved by adopting a side surface roughening mode, the integral brightness of the chip is improved, the proportion of emergent light on the side surface is increased, and the light emitting angle of the chip is increased; the insulating passivation layer and the reflecting layer are covered above the prepared chip, so that the requirement of a Mini LED chip on a large light-emitting angle can be met while the side wall of the chip is protected.)

1. A method for manufacturing a Mini LED chip is characterized by comprising the following steps:

preparing a conical patterned dielectric film on a substrate, and growing an epitaxial layer on one end of the patterned dielectric film, which is far away from the substrate;

etching a cutting path on the epitaxial layer;

etching the side wall of the cutting channel and the patterned dielectric film exposed at the bottom, and forming a lower side wall of the regular trapezoid cutting channel at the position of the patterned dielectric film;

corroding the side wall of the cutting street to form a rough side wall of the cutting street;

and covering an insulating passivation layer and a reflecting layer above the prepared chip to obtain the Mini LED chip.

2. The method of claim 1, wherein the step of forming a tapered patterned dielectric film on the substrate comprises:

and depositing a layer of dielectric film on the substrate, and photoetching and etching the dielectric film according to the photoetching mask pattern to obtain the conical patterned dielectric film.

3. The method of claim 1, wherein the step of etching the scribe lines on the epitaxial layer comprises:

using photoresist or a dielectric layer as a mask to etch the cutting channel of the epitaxial layer, and forming an upper side wall of the inverted trapezoidal cutting channel at the position of the epitaxial layer;

the lower side wall of the cutting channel which forms the regular trapezoid at the position of the patterned dielectric film comprises:

and the top surface of the formed lower side wall of the cutting channel is the bottom surface of the upper side wall of the cutting channel.

4. The method of claim 1, wherein the growing an epitaxial layer on the patterned dielectric film at an end away from the substrate comprises:

sequentially growing N-type gallium nitride, a multilayer quantum well and P-type gallium nitride on one end of the patterned dielectric film, which is far away from the substrate, so as to obtain an epitaxial layer;

before the epitaxial layer is etched by the cutting path, the method comprises the following steps:

and photoetching and etching the epitaxial layer to expose the surface of the N-type gallium nitride.

5. The method of claim 1, wherein the etching the street sidewalls to form rough street sidewalls comprises:

under the preset temperature and time, etching the side wall of the cutting channel by using a coarsening etching solution, and forming a rough side wall of the cutting channel on the part of the epitaxial layer with the N-type gallium nitride;

the roughening corrosion solution comprises KOH, NaOH and H₃PO₄Or TMAH.

6. The method of claim 1, wherein the step of covering the chip with the passivation and reflective insulation layer comprises:

covering a current expansion layer in a region of the prepared chip where the epitaxial layer is not subjected to photoetching and etching;

and respectively manufacturing a P-type ohmic contact metal layer and an N-type ohmic contact metal layer on the surfaces of the current spreading layer and the N-type gallium nitride.

7. The method of claim 1, wherein the step of covering the insulating passivation layer and the reflective layer on the prepared chip comprises:

covering an insulating passivation layer and a reflecting layer above the prepared chip in sequence, and exposing a P-type ohmic contact metal layer and an N-type ohmic contact metal layer;

the method comprises the following steps of covering an insulating passivation layer and a reflecting layer above the prepared chip:

and respectively manufacturing a P-type welding metal electrode and an N-type welding metal electrode above the P-type ohmic contact metal layer and the N-type ohmic contact metal layer.

8. The method of claim 7, wherein the step of covering the insulating passivation layer and the reflective layer on the prepared chip further comprises:

covering an insulating passivation layer and a reflecting layer above the chip without the exposed N-type gallium nitride in sequence, and exposing the P-type ohmic contact metal layer;

and covering an insulating passivation layer above the chip exposed out of the N-type gallium nitride, and exposing out of the N-type ohmic contact metal layer.

9. A Mini LED chip is characterized by comprising a substrate, a graphical dielectric film, an epitaxial layer, a current expansion layer, a P-type ohmic contact metal layer, an N-type ohmic contact metal layer, an insulation passivation layer, a reflecting layer, a P-type welding metal electrode and an N-type welding metal electrode;

the patterned dielectric film is conical and is positioned right above the substrate;

the epitaxial layer is positioned at one end of the patterned dielectric film far away from the substrate;

the epitaxial layer comprises an exposed N-type gallium nitride region and an unexposed N-type gallium nitride region;

the epitaxial layer of the exposed N-type gallium nitride region comprises a cutting channel, the upper side wall of the cutting channel is in an inverted trapezoid shape at the position of the epitaxial layer, the lower side wall of the cutting channel is in a regular trapezoid shape at the position of the patterned dielectric film, and the top surface of the lower side wall of the cutting channel is the bottom surface of the upper side wall of the cutting channel;

the current extension layer is positioned at one end, far away from the substrate, of the epitaxial layer of the N-type gallium nitride region which is not exposed;

the P-type ohmic contact metal layer and the N-type ohmic contact metal layer are respectively positioned on the surfaces of the current spreading layer and the N-type gallium nitride;

the insulating passivation layer and the reflecting layer are positioned on the surface of the chip, and the P-type ohmic contact metal layer and the N-type ohmic contact metal layer are exposed;

the P-type welding metal electrode and the N-type welding metal electrode are positioned above the P-type ohmic contact metal layer and the N-type ohmic contact metal layer.

10. The Mini LED chip of claim 9, wherein said insulating passivation layer and said reflective layer are on the surface of said chip, and exposing said P-type ohmic contact metal layer and said N-type ohmic contact metal layer further comprises:

the insulating passivation layer is positioned on the surface of the chip and exposes the P-type ohmic contact metal layer and the N-type ohmic contact metal layer;

the reflecting layer is positioned on the surface of the chip without exposing the N-type gallium nitride region, and the P-type ohmic contact metal layer is exposed.

Technical Field

The invention relates to the field of LED manufacturing, in particular to a Mini LED chip and a manufacturing method thereof.

Background

The Mini LED is an LED chip with the size of 100 microns, and is mainly applied to backlight and direct display. In size, the size of a single LED chip of the Mini LED is 50-200 μm, and the pixel pitch is about 0.5-1 mm. Compared with the traditional LED chip backlight product, the LED backlight lamp has smaller dot spacing, so that more LED backlight lamp beads can be integrated on the same display screen, the screen is divided into more fine backlight partitions, the realization of more fine regional light emitting adjustment is facilitated, and the contrast close to an OLED screen can be possessed. In addition, compared with an OLED screen, the Mini LED backlight screen has the advantages of long service life, difficulty in screen burning and the like. Mini LED's shortcoming has integrated more lamp pearls in a poor light, and thickness is difficult to be made thin, and more lamp pearls in a poor light gather and also produce bigger heat easily, require to the equipment heat dissipation higher. Large-angle Mini LED can realize large lamp bead interval (pitch), thereby reducing the number of lamp beads. Because the Mini LED has a small chip size, the proportion of the side area of the Mini LED to the total light-emitting area of the chip is large, and therefore the light-emitting angle of the chip can be effectively increased by increasing the side light-emitting efficiency.

The current method for realizing a large light-emitting angle of a Mini LED is to plate a partial reflecting film on the back surface of a transparent substrate, so that reflected light escapes from the side surface, and the light-emitting angle is increased. However, the method has the disadvantage that the absorption of the epitaxial light is increased due to the increase of the reflection times of the light on the upper surface and the lower surface of the chip, so that the brightness of the side light is greatly reduced, and the overall brightness of the Mini LED backlight chip is further reduced.

Disclosure of Invention

The technical problem to be solved by the invention is as follows: the Mini LED chip and the manufacturing method thereof are provided, and can improve the light extraction efficiency of the side surface of the chip, further improve the overall brightness of the chip and increase the light emitting angle of the chip.

In order to solve the technical problems, the invention adopts the technical scheme that:

a method for manufacturing a Mini LED chip comprises the following steps:

preparing a conical patterned dielectric film on a substrate, and growing an epitaxial layer on one end of the patterned dielectric film, which is far away from the substrate;

etching a cutting path on the epitaxial layer;

etching the side wall of the cutting channel and the patterned dielectric film exposed at the bottom, and forming a lower side wall of the regular trapezoid cutting channel at the position of the patterned dielectric film;

corroding the side wall of the cutting street to form a rough side wall of the cutting street;

and covering an insulating passivation layer and a reflecting layer above the prepared chip to obtain the Mini LED chip.

In order to solve the technical problem, the invention adopts another technical scheme as follows:

a Mini LED chip comprises a substrate, a graphical dielectric film, an epitaxial layer, a current expansion layer, a P-type ohmic contact metal layer, an N-type ohmic contact metal layer, an insulation passivation layer, a reflecting layer, a P-type welding metal electrode and an N-type welding metal electrode;

the patterned dielectric film is conical and is positioned right above the substrate;

the epitaxial layer is positioned at one end of the patterned dielectric film far away from the substrate;

the epitaxial layer comprises an exposed N-type gallium nitride region and an unexposed N-type gallium nitride region;

the epitaxial layer of the exposed N-type gallium nitride region comprises a cutting channel, the upper side wall of the cutting channel is in an inverted trapezoid shape at the position of the epitaxial layer, the lower side wall of the cutting channel is in a regular trapezoid shape at the position of the patterned dielectric film, and the top surface of the lower side wall of the cutting channel is the bottom surface of the upper side wall of the cutting channel;

the current extension layer is positioned at one end, far away from the substrate, of the epitaxial layer of the N-type gallium nitride region which is not exposed;

the P-type ohmic contact metal layer and the N-type ohmic contact metal layer are respectively positioned on the surfaces of the current spreading layer and the N-type gallium nitride;

the insulating passivation layer and the reflecting layer are positioned on the surface of the chip, and the P-type ohmic contact metal layer and the N-type ohmic contact metal layer are exposed;

the P-type welding metal electrode and the N-type welding metal electrode are positioned above the P-type ohmic contact metal layer and the N-type ohmic contact metal layer.

The invention has the beneficial effects that: preparing a conical patterned dielectric film on a substrate, and growing an epitaxial layer on one end of the patterned dielectric film, which is far away from the substrate; etching the side wall of the cutting channel and the patterned dielectric film exposed at the bottom after etching the cutting channel of the epitaxial layer, wherein the lower side wall of the cutting channel in a regular trapezoid shape can be formed at the position of the patterned dielectric film because the patterned dielectric film is in a conical shape; the side wall of the cutting channel is corroded to form a rough side wall surface, so that the efficiency of extracting light from the side surface of the chip is improved by adopting a side surface roughening mode, the integral brightness of the chip is improved, the proportion of emergent light on the side surface is increased, and the light emitting angle of the chip is increased; the insulating passivation layer and the reflecting layer are covered above the prepared chip, so that the requirement of a Mini LED chip on a large light-emitting angle can be met while the side wall of the chip is protected.

Drawings

Fig. 1 is a flowchart of a method for manufacturing a Mini LED chip according to an embodiment of the present invention;

fig. 2 is a schematic structural diagram of a Mini LED chip according to an embodiment of the present invention;

FIG. 3 is a schematic view of a photolithographic mask of a method for manufacturing a Mini LED chip according to an embodiment of the present invention;

FIG. 4 is a schematic structural diagram of a Mini LED chip manufacturing method without side wall etching roughening according to an embodiment of the present invention;

FIG. 5 is a schematic structural diagram of a reflective layer deposited after photolithography in a method for manufacturing a Mini LED chip according to an embodiment of the present invention;

fig. 6 is a schematic structural diagram of a method for manufacturing a Mini LED chip according to an embodiment of the present invention without forming P-type and N-type ohmic contact metal layers;

FIG. 7 is a schematic structural diagram of a Mini LED chip manufacturing method according to an embodiment of the present invention, in which the P-type and N-type ohmic contact metal layers are not formed, and the reflective layer is deposited after photolithography;

description of reference numerals:

1. a substrate; 2. patterning the dielectric film; 3. n-type gallium nitride; 4. a plurality of layers of quantum wells; 5. p-type gallium nitride; 6. a current spreading layer; 7. an insulating passivation layer; 8. a reflective layer; 9. a P-type ohmic contact metal layer; 10. a P-type weld metal electrode; 11. an N-type ohmic contact metal layer; 12. an N-type weld metal electrode; 13. and cutting a channel.

Detailed Description

In order to explain technical contents, achieved objects, and effects of the present invention in detail, the following description is made with reference to the accompanying drawings in combination with the embodiments.

Referring to fig. 1, an embodiment of the present invention provides a method for manufacturing a Mini LED chip, including:

preparing a conical patterned dielectric film on a substrate, and growing an epitaxial layer on one end of the patterned dielectric film, which is far away from the substrate;

etching a cutting path on the epitaxial layer;

etching the side wall of the cutting channel and the patterned dielectric film exposed at the bottom, and forming a lower side wall of the regular trapezoid cutting channel at the position of the patterned dielectric film;

corroding the side wall of the cutting street to form a rough side wall of the cutting street;

and covering an insulating passivation layer and a reflecting layer above the prepared chip to obtain the Mini LED chip.

From the above description, the beneficial effects of the present invention are: preparing a conical patterned dielectric film on a substrate, and growing an epitaxial layer on one end of the patterned dielectric film, which is far away from the substrate; etching the side wall of the cutting channel and the patterned dielectric film exposed at the bottom after etching the cutting channel of the epitaxial layer, wherein the lower side wall of the cutting channel in a regular trapezoid shape can be formed at the position of the patterned dielectric film because the patterned dielectric film is in a conical shape; the side wall of the cutting channel is corroded to form a rough side wall surface, so that the efficiency of extracting light from the side surface of the chip is improved by adopting a side surface roughening mode, the integral brightness of the chip is improved, the proportion of emergent light on the side surface is increased, and the light emitting angle of the chip is increased; the insulating passivation layer and the reflecting layer are covered above the prepared chip, so that the requirement of a Mini LED chip on a large light-emitting angle can be met while the side wall of the chip is protected.

Further, the step of preparing the tapered patterned dielectric film on the substrate comprises:

and depositing a layer of dielectric film on the substrate, and photoetching and etching the dielectric film according to the photoetching mask pattern to obtain the conical patterned dielectric film.

As can be seen from the above description, the photolithographic mask pattern is used to perform photolithography and etching on the dielectric film on the substrate to obtain the tapered patterned dielectric film, which facilitates obtaining the regular trapezoidal sidewall during subsequent etching of the patterned dielectric film.

Further, the step of performing scribe line etching on the epitaxial layer includes:

using photoresist or a dielectric layer as a mask to etch the cutting channel of the epitaxial layer, and forming an upper side wall of the inverted trapezoidal cutting channel at the position of the epitaxial layer;

the lower side wall of the cutting channel which forms the regular trapezoid at the position of the patterned dielectric film comprises:

and the top surface of the formed lower side wall of the cutting channel is the bottom surface of the upper side wall of the cutting channel.

According to the description, the epitaxial layer is etched in the cutting way, the inverted trapezoidal cutting way side wall can be formed at the position of the epitaxial layer, and the whole cutting way side wall is in a folded line type of inverted trapezoid and positive trapezoid in combination with the positive trapezoidal cutting way side wall at the position of the graphical dielectric film, so that the subsequent reflection film deposited on the positive trapezoidal cutting way side wall is reduced conveniently.

Further, growing an epitaxial layer on one end of the patterned dielectric film far away from the substrate comprises:

sequentially growing N-type gallium nitride, a multilayer quantum well and P-type gallium nitride on one end of the patterned dielectric film, which is far away from the substrate, so as to obtain an epitaxial layer;

before the epitaxial layer is etched by the cutting path, the method comprises the following steps:

and photoetching and etching the epitaxial layer to expose the surface of the N-type gallium nitride.

As can be seen from the above description, before performing the scribe line etching, the epitaxial layer is first subjected to photolithography and etching to expose the surface of the N-type gallium nitride, which is convenient for performing the scribe line etching at the position where the N-type gallium nitride is exposed subsequently.

Further, the etching the side wall of the scribe line to form a rough side wall of the scribe line includes:

under the preset temperature and time, etching the side wall of the cutting channel by using a coarsening etching solution, and forming a rough side wall of the cutting channel on the part of the epitaxial layer with the N-type gallium nitride;

the roughening corrosion solution comprises KOH, NaOH and H₃PO₄Or TMAH.

As can be seen from the above description, the exposed part of the epitaxial surface after the patterned dielectric film is etched away is an N-polar surface, so that the solution can easily etch the epitaxial surface and form a rough sidewall; the roughening corrosion solution comprises KOH, NaOH and H₃PO₄And TMAH, etc., can be etched in accordance with the corresponding etching temperature and time.

Further, the method for covering the insulating passivation layer and the reflecting layer on the chip comprises the following steps:

covering a current expansion layer in a region of the prepared chip where the epitaxial layer is not subjected to photoetching and etching;

and respectively manufacturing a P-type ohmic contact metal layer and an N-type ohmic contact metal layer on the surfaces of the current spreading layer and the N-type gallium nitride.

Further, the covering of the insulating passivation layer and the reflective layer on the chip manufactured as above includes:

covering an insulating passivation layer and a reflecting layer above the prepared chip in sequence, and exposing a P-type ohmic contact metal layer and an N-type ohmic contact metal layer;

the method comprises the following steps of covering an insulating passivation layer and a reflecting layer above the prepared chip:

and respectively manufacturing a P-type welding metal electrode and an N-type welding metal electrode above the P-type ohmic contact metal layer and the N-type ohmic contact metal layer.

From the above description, the insulating passivation layer can protect the side wall of the chip, and the reflective layer can be plated just above the prepared chip, so that light can easily exit from the lower side wall of the cutting channel to the outside of the chip, the side light extraction efficiency is increased, and the light emitting angle of the chip is increased.

Further, the step of covering the insulating passivation layer and the reflecting layer on the prepared chip further comprises the following steps:

covering an insulating passivation layer and a reflecting layer above the chip without the exposed N-type gallium nitride in sequence, and exposing the P-type ohmic contact metal layer;

and covering an insulating passivation layer above the chip exposed out of the N-type gallium nitride, and exposing out of the N-type ohmic contact metal layer.

As can be seen from the above description, the reflective layer only covers the region directly above the P-type GaN layer. Therefore, the side wall of the cutting channel is not covered by an insulating full-spectrum reflecting layer, and light emitted from the quantum well can be easily emitted to the outside of the chip when encountering the rough side wall of the cutting channel, so that the light extraction efficiency of the side wall of the cutting channel is greatly improved, and the light emitting angle of the chip is further increased.

Referring to fig. 2, another embodiment of the invention provides a Mini LED chip, including a substrate, a patterned dielectric film, an epitaxial layer, a current spreading layer, a P-type ohmic contact metal layer, an N-type ohmic contact metal layer, an insulating passivation layer, a reflective layer, a P-type bonding metal electrode, and an N-type bonding metal electrode;

the patterned dielectric film is conical and is positioned right above the substrate;

the epitaxial layer is positioned at one end of the patterned dielectric film far away from the substrate;

the epitaxial layer comprises an exposed N-type gallium nitride region and an unexposed N-type gallium nitride region;

the epitaxial layer of the exposed N-type gallium nitride region comprises a cutting channel, the upper side wall of the cutting channel is in an inverted trapezoid shape at the position of the epitaxial layer, the lower side wall of the cutting channel is in a regular trapezoid shape at the position of the patterned dielectric film, and the top surface of the lower side wall of the cutting channel is the bottom surface of the upper side wall of the cutting channel;

the current extension layer is positioned at one end, far away from the substrate, of the epitaxial layer of the N-type gallium nitride region which is not exposed;

the P-type ohmic contact metal layer and the N-type ohmic contact metal layer are respectively positioned on the surfaces of the current spreading layer and the N-type gallium nitride;

the insulating passivation layer and the reflecting layer are positioned on the surface of the chip, and the P-type ohmic contact metal layer and the N-type ohmic contact metal layer are exposed;

the P-type welding metal electrode and the N-type welding metal electrode are positioned above the P-type ohmic contact metal layer and the N-type ohmic contact metal layer.

As can be seen from the above description, a tapered patterned dielectric film is prepared on a substrate, and an epitaxial layer is grown on one end of the patterned dielectric film away from the substrate; etching the side wall of the cutting channel and the patterned dielectric film exposed at the bottom after etching the cutting channel of the epitaxial layer, wherein the lower side wall of the cutting channel in a regular trapezoid shape can be formed at the position of the patterned dielectric film because the patterned dielectric film is in a conical shape; the side wall of the cutting channel is corroded to form a rough side wall surface, so that the efficiency of extracting light from the side surface of the chip is improved by adopting a side surface roughening mode, the integral brightness of the chip is improved, the proportion of emergent light on the side surface is increased, and the light emitting angle of the chip is increased; the insulating passivation layer and the reflecting layer are covered above the prepared chip, so that the requirement of a Mini LED chip on a large light-emitting angle can be met while the side wall of the chip is protected.

Further, the insulating passivation layer and the reflective layer are located on the surface of the chip, and the exposing of the P-type ohmic contact metal layer and the N-type ohmic contact metal layer further includes:

the insulating passivation layer is positioned on the surface of the chip and exposes the P-type ohmic contact metal layer and the N-type ohmic contact metal layer;

the reflecting layer is positioned on the surface of the chip without exposing the N-type gallium nitride region, and the P-type ohmic contact metal layer is exposed.

As can be seen from the above description, the reflective layer only covers the region directly above the P-type GaN layer. Therefore, the side wall of the cutting channel is not covered by an insulating full-spectrum reflecting layer, and light emitted from the quantum well can be easily emitted to the outside of the chip when encountering the rough side wall of the cutting channel, so that the light extraction efficiency of the side wall of the cutting channel is greatly improved, and the light emitting angle of the chip is further increased.

According to the Mini LED chip and the manufacturing method thereof, the method for increasing the light extraction efficiency of the side wall of the Mini LED chip can increase the light emitting angle of the chip and reduce the reduction range of the brightness of the chip, so that the wide-angle Mini LED backlight chip can be widely applied to various backlight products, and the following description is provided through a specific implementation mode:

example one

Referring to fig. 1 to 4 and 6, a method for manufacturing a Mini LED chip includes the steps of:

s1, preparing a conical patterned dielectric film 2 on the substrate, and growing an epitaxial layer on one end of the patterned dielectric film 2, which is far away from the substrate 1.

Wherein, the step of preparing the conical patterned dielectric film 2 on the substrate comprises the following steps:

and depositing a dielectric film on the substrate, and photoetching and etching the dielectric film according to the photoetching mask pattern to obtain the conical patterned dielectric film 2.

Specifically, in this embodiment, a dielectric film is deposited on the substrate, and the dielectric film may be SiO₂、Al₂O₃Or Si₃N₄Then, a patterned dielectric film 2 is formed on the dielectric film by photolithography and etching, and a schematic diagram of a photolithography mask pattern is shown in fig. 3.

Wherein, growing an epitaxial layer on one end of the patterned dielectric film 2 far away from the substrate 1 comprises:

and sequentially growing N-type gallium nitride 3, a multilayer quantum well 4 and P-type gallium nitride 5 on one end of the patterned dielectric film, which is far away from the substrate, so as to obtain an epitaxial layer.

Specifically, in the present embodiment, an LED epitaxial layer is epitaxially grown on the substrate 1 having the patterned dielectric film 2, and the epitaxial layer mainly includes N-type gallium nitride 3, a multilayer quantum well 4, and P-type gallium nitride 5.

And S2, etching the cutting channel 13 on the epitaxial layer.

Wherein, before the etching of the cutting path on the epitaxial layer, the method comprises the following steps:

and photoetching and etching the epitaxial layer to expose the surface of the N-type gallium nitride 3.

Wherein the etching of the scribe lines 13 of the epitaxial layer comprises:

and etching the cutting channel 13 of the epitaxial layer by using the photoresist or the dielectric layer as a mask, and forming the upper side wall of the inverted trapezoidal cutting channel at the position of the epitaxial layer.

Specifically, referring to fig. 4, after the epitaxial wafer is subjected to the photolithography and etching process, the surface of the N-type gallium nitride 3 is exposed; the streets 13 are then etched around the chip using the photoresist, the dielectric layer, or a combination of both as a mask.

And S3, etching the side wall of the cutting channel and the patterned dielectric film 2 exposed from the bottom, and forming a lower side wall of the cutting channel in a regular trapezoid shape at the position of the patterned dielectric film 2.

Specifically, after the etching of the cutting street 13 is completed, the patterned medium 2 exposed out of the bottom and the side wall of the cutting street 13 is removed by wet etching, the top surface of the lower side wall of the cutting street is the bottom surface of the upper side wall of the cutting street, and the appearance of the side wall of the integral cutting street formed in this way is a broken line type of an inverted trapezoid and a regular trapezoid.

And S4, corroding the side wall of the cutting street to form a rough side wall of the cutting street.

Under the preset temperature and time, etching the side wall of the cutting channel by using a coarsening etching solution, and forming a rough side wall of the cutting channel on the epitaxial layer part with the N-type gallium nitride 3;

the roughening corrosion solution comprises KOH, NaOH and H₃PO₄Or TMAH.

Specifically, referring to fig. 2, the epitaxial etching of the sidewall of the scribe line is performed at a certain temperature to finally form a rough sidewall of the scribe line. Because the crystallinity of the epitaxial layer adjacent to the dielectric layer 2 is general, and part of the epitaxial surface is N-polar, the epitaxial layer is easily corroded by the solution, and a rough side wall morphology is formed, and in the prior art, because most of the side wall of the cutting channel above the patterned medium is Ga-polar, the roughness of the pattern formed by roughening the solution is low, and the roughening degree of etching the flip chip is weak.

The roughening corrosion solution commonly used is KOH, NaOH or H₃PO₄TMAH and the like, need to be corroded at different temperatures and time, and the trapezoid rough morphology of the lower part of the side wall is more beneficial to taking out light from the side face of the chip.

And S5, covering an insulating passivation layer 7 and a reflecting layer 8 above the prepared chip to obtain the Mini LED chip.

Wherein, before covering the insulating passivation layer 7 and the reflecting layer 8 above the prepared chip, the method comprises the following steps:

covering a current expansion layer 6 in a region of the prepared chip where the epitaxial layer is not subjected to photoetching and etching;

and respectively manufacturing a P-type ohmic contact metal layer 9 and an N-type ohmic contact metal layer 11 on the surfaces of the current spreading layer and the N-type gallium nitride.

Wherein, covering the insulating passivation layer 7 and the reflecting layer 8 above the prepared chip comprises:

sequentially covering an insulating passivation layer 7 and a reflecting layer 8 above the prepared chip, and exposing the P-type ohmic contact metal layer 9 and the N-type ohmic contact metal layer 11;

after covering the insulating passivation layer 7 and the reflecting layer 8 on the chip prepared in the above way, the method comprises the following steps:

and respectively manufacturing a P-type welding metal electrode 10 and an N-type welding metal electrode 12 above the P-type ohmic contact metal layer and the N-type ohmic contact metal layer.

Specifically, in this embodiment, the current spreading layer 6 is coated with a film, the P-type ohmic contact metal layer 9 and the N-type ohmic contact metal layer 11 are fabricated, and then the insulating passivation layer 7 is deposited and patterned, and the insulating full-spectrum reflective layer 8 is deposited, etched and etched to form a pattern;

after the reflecting layer 8 is covered, a P-type welding metal electrode 10 and an N-type welding metal electrode 12 are required to be manufactured; cutting the splinters to form core grains; testing, sorting and film reversing of the chip; flip-chip packaging is carried out on the PCB substrate in a solder paste or AuSn eutectic mode, so that light of the chip is emitted from the back of the sapphire substrate 1;

and by combining the original process of plating a partial reflecting film on the back surface of the substrate, part of light which is originally directly emitted from the back surface of the sapphire can be reflected back to the chip and then emitted from the side surface of the chip after being reflected again by the front reflecting layer, so that the ratio of side surface luminescence of the chip is further improved, and the requirement of a large luminescence angle of the Mini LED chip is met.

Therefore, referring to fig. 2 and 4, the insulating full spectrum reflective layer 8 is deposited on the scribe line of the conventional flip chip, but the light emitted from the multiple quantum well layer 4 is reflected back to the inside of the chip when encountering the side wall of the scribe line, so that the side light emission is reduced, and the chip light emission angle is reduced. After the etching and coarsening process of the side wall of the cutting channel is adopted in the embodiment, even if the side wall of the cutting channel is covered by the full-spectrum reflecting layer 8, the whole part of the side wall of the cutting channel close to the lower part is in the shape of a regular trapezoid, the full-spectrum reflecting layer 8 covered on the side wall of the cutting channel is very thin, the reflecting efficiency is poor, the surface roughness of the side wall of the part is large, and the light is easy to exit from the side wall of the regular trapezoid to the outside of the chip by the three points, so that the light taking efficiency of the side surface is improved, and the light emitting angle of the chip is increased.

In another alternative embodiment, referring to fig. 6, the P-type ohmic contact metal layer 9 and the N-type ohmic contact metal layer 11 are not formed, and ohmic contacts are directly formed between the P-type bonding metal electrode 10 and the N-type bonding metal electrode 12 and the current spreading layer 6 or the N-type gallium nitride 3.

Example two

Referring to fig. 1, fig. 3, fig. 5 and fig. 7, the difference between the first embodiment and the second embodiment is that the deposition position of the reflective film is different, specifically:

the step of covering the insulating passivation layer and the reflecting layer above the prepared chip further comprises the following steps:

covering an insulating passivation layer and a reflecting layer above the chip without the exposed N-type gallium nitride, and exposing the P-type ohmic contact metal layer;

and covering an insulating passivation layer above the chip exposed out of the N-type gallium nitride, and exposing out of the N-type ohmic contact metal layer.

In an alternative embodiment, referring to fig. 5, the insulating full spectrum reflective layer 8 is first formed by photolithography, and then patterned by lift-off, so that the insulating full spectrum reflective layer 8 only covers the region directly above the P-type gan 5. Therefore, the side wall of the cutting channel is not covered by an insulating full-spectrum reflecting layer, and light emitted from the quantum well can be easily emitted to the outside of the chip when encountering the rough side wall of the cutting channel, so that the light taking-out efficiency of the side wall of the cutting channel is greatly improved, and the light emitting angle of the chip is increased.

In another alternative embodiment, referring to fig. 7, the P-type ohmic contact metal layer 9 and the N-type ohmic contact metal layer 11 are not formed, and are first subjected to photolithography and then deposited with the insulating full spectrum reflective layer 8, so that the insulating full spectrum reflective layer is not covered on the sidewall of the scribe line while ohmic contact is directly formed between the P-type bonding metal electrode 10 and the N-type bonding metal electrode 12 and the current spreading layer 6 or the N-type gallium nitride 3, thereby increasing the light emitting angle of the chip.

EXAMPLE III

Referring to fig. 2, 5 to 7, a Mini LED chip includes a substrate, a patterned dielectric film, an epitaxial layer, a current spreading layer, a P-type ohmic contact metal layer, an N-type ohmic contact metal layer, an insulating passivation layer, a reflective layer, a P-type bonding metal electrode, and an N-type bonding metal electrode;

the graphical dielectric film is in a cone shape and is positioned right above the substrate;

the epitaxial layer is positioned at one end of the graphical dielectric film far away from the substrate;

the epitaxial layer comprises an exposed N-type gallium nitride region and an unexposed N-type gallium nitride region;

the epitaxial layer of the exposed N-type gallium nitride region comprises a cutting channel, the upper side wall of the cutting channel is in an inverted trapezoid shape at the position of the epitaxial layer, the lower side wall of the cutting channel is in a regular trapezoid shape at the position of the patterned dielectric film, and the top surface of the lower side wall of the cutting channel is the bottom surface of the upper side wall of the cutting channel;

the current extension layer is positioned at one end, far away from the substrate, of the epitaxial layer of the N-type gallium nitride region which is not exposed;

the P-type ohmic contact metal layer and the N-type ohmic contact metal layer are respectively positioned on the surfaces of the current expansion layer and the N-type gallium nitride;

the insulating passivation layer and the reflecting layer are positioned on the surface of the chip, and the P-type ohmic contact metal layer and the N-type ohmic contact metal layer are exposed;

the P-type welding metal electrode and the N-type welding metal electrode are positioned above the P-type ohmic contact metal layer and the N-type ohmic contact metal layer.

In an alternative embodiment, referring to fig. 5, the insulating full spectrum reflective layer is deposited by photolithography, such that the insulating full spectrum reflective layer only covers the region directly above the P-type gan.

In another alternative embodiment, referring to fig. 6, the P-type ohmic contact metal layer and the N-type ohmic contact metal layer are not formed, and ohmic contacts are directly formed by the P-type welding metal electrode and the N-type welding metal electrode and the current spreading layer or the N-type gallium nitride.

In another alternative embodiment, referring to fig. 7, the P-type ohmic contact metal layer and the N-type ohmic contact metal layer are not formed, and the insulating full spectrum reflective layer is deposited by photolithography, so that the insulating full spectrum reflective layer only covers the region directly above the P-type gallium nitride.

In summary, according to the Mini LED chip and the manufacturing method thereof provided by the present invention, a tapered patterned dielectric film is prepared on a substrate, and an epitaxial layer is grown on one end of the patterned dielectric film away from the substrate; etching the cutting channel of the epitaxial layer, wherein after the etching of the cutting channel is finished, partial graphical media are exposed at the bottom of the side wall of the cutting channel, the side wall of the cutting channel and the graphical media film exposed at the bottom need to be etched, and the lower side wall of the cutting channel in a regular trapezoid shape can be formed at the position of the graphical media film because the graphical media film is in a cone shape; at the moment, the exposed epitaxy is an N-polar surface, so that anisotropic corrosion is easily performed on the side wall of the cutting channel by using a solution, and a relatively rough side wall surface can be formed, the efficiency of extracting light from the side surface of the chip is improved by adopting a side surface roughening mode, the overall brightness of the chip is improved, the proportion of side emergent light is increased, and the effect of increasing the light emitting angle is realized; because most of the side walls of the cutting channels above the patterned medium are Ga-polar, the roughness of the pattern formed by roughening the solution is low, the roughening degree is weak, the upper side walls of the cutting channels are inverted trapezoidal, and the top surfaces of the lower side walls of the cutting channels are the bottom surfaces of the upper side walls of the cutting channels. The appearance of the side wall of the integral cutting channel formed in the way is of a broken line type of an inverted trapezoid and a regular trapezoid, and the rough appearance of the regular trapezoid of the lower part of the side wall is more beneficial to taking out light from the side face of the chip, so that the integral brightness of the chip is improved, and meanwhile, the light emitting angle is increased. When the reflecting film is covered, the reflecting film can be covered on the chip, or the reflecting layer can be covered on the P-type gallium nitride epitaxial layer; when the reflecting layer is only covered above the P-type gallium nitride epitaxial layer, the side light taking efficiency of the chip is higher, the light emitting angle of the chip can be further increased, and in combination with the original process of plating a partial reflecting film on the back surface of the substrate, part of light which is originally directly emitted from the back surface of the sapphire can be reflected back to the chip and emitted from the side surface of the chip after being reflected again by the front reflecting layer, so that the proportion of side light emission of the chip is further improved, and the requirement of the large light emitting angle of the Mini LED chip is met.

The above description is only an embodiment of the present invention, and not intended to limit the scope of the present invention, and all equivalent changes made by using the contents of the present specification and the drawings, or applied directly or indirectly to the related technical fields, are included in the scope of the present invention.