Micro-RCLED device based on ITO shoulder structure and preparation method thereof

Abstract

The invention discloses a Micro-RCLED device based on an ITO shoulder structure and a preparation method thereof, the device comprises a substrate layer, a bonding metal layer, a first reflector layer, an ITO current expansion layer and a gallium nitride epitaxial layer which are sequentially arranged from bottom to top, and the gallium nitride epitaxial layer comprises a p-GaN layer, an MQW layer and an n-GaN layer which are sequentially arranged from bottom to top. The mesa sizes of the bonding metal layer, the ITO current expansion layer and the first reflector layer are sequentially reduced and arranged in an I shape, the mesa size of the gallium nitride epitaxial layer is not larger than that of the ITO current expansion layer, and a metal electrode layer in butt joint with a shoulder surface at the bottom of the ITO current expansion layer is arranged on the bonding metal layer outside the first reflector layer and the ITO current expansion layer. A DBR reflector layer is arranged on the n-GaN layer, and the reflectivity of the DBR reflector layer to a device emission light source is smaller than that of the first reflector layer. According to the method, the yield of the Micro-RCLED chip in mass production is greatly improved, a CMP-ICP-CMP resonant cavity layer thinning method is innovatively provided in substrate transfer, and the phenomena of device open circuit and device failure are reduced.

Description

Technical Field

[0001] The invention relates to the field of semiconductor electronic technology, and in particular to a Micro-RCLED device based on an ITO shoulder structure and a preparation method thereof. Background Art

[0002] With the rapid development of display technology, Micro-LED display technology with a single light-emitting unit less than 100um has excellent characteristics such as high luminous efficiency, high brightness, high response speed and reliability. It is gradually developing into the next generation of display technology, and it also shows great potential in the fields of optogenetics and photodynamic medicine. But at the same time, Micro-LED also faces problems such as excessive divergence angle and excessive half-width of the luminescent peak spectrum. In the display field, excessive divergence angle and excessive half-width of the luminescent peak spectrum will lead to serious problems such as serious color difference, color crosstalk, and contrast reduction. In the field of photodynamic medicine, it will seriously affect the accuracy and effect of treatment. Therefore, by introducing a resonant cavity structure (Resonant Cavity) at the top and bottom of the Micro-LED device, the divergence angle of the device can be significantly optimized and the half-width of the device can be reduced to obtain high-precision optoelectronic band control.

[0003] However, existing Micro-RCLED devices are often prepared by directly growing each layer of film structure. However, during the growth process, the in-situ growth between different system materials will produce large lattice defects and dislocations, resulting in low device efficiency and the inability to achieve the growth of any band, especially the preparation of blue and green Micro-RCLEDs. Therefore, in recent years, the preparation of Micro-RCLEDs by substrate transfer can fully avoid the growth defects between different system materials, such as the Chinese patent with publication number CN113299806A and the Chinese patent with authorization announcement number CN 105609602 B.

[0004] However, this method also faces the following problems: During the preparation process, the resonant cavity structure is introduced through substrate transfer, and the gallium nitride film thickness needs to be precisely controlled. During preparation, since p-GaN is only a few hundred nanometers thick and the bottom is a whole reflector, when preparing the device table, it is often insufficient or excessive etching, resulting in the device not being etched to the P-GaN layer or etching through the ITO current spreading layer, resulting in insulation and non-conductivity. At the same time, the traditional stripping and thinning method has a great loss in the thickness of the surface GaN, and the speed cannot be precisely controlled, which often results in a large thickness difference between the edge and the center of the wafer, and even the edge gallium nitride is completely worn out. It is difficult to obtain a high-precision designed GaN film thickness, which makes the chip yield extremely low, seriously hindering the industrialization and application prospects of Micro-RCLED devices. Summary of the invention

[0005] The purpose of the present invention is to address the shortcomings of the prior art and provide a Micro-RCLED device based on an ITO shoulder structure and a preparation method thereof that can effectively improve the chip yield, accurately control the thickness of the GaN light-emitting layer that constitutes the middle layer of the resonant cavity, and achieve large-scale and high-yield preparation of a small divergence angle and narrow the spectral half-width.

[0006] The Micro-RCLED device based on the ITO shoulder structure provided by the present invention comprises a substrate layer, a bonding metal layer, a first reflector layer, an ITO current expansion layer and a gallium nitride epitaxial layer arranged in sequence from bottom to top, wherein the gallium nitride epitaxial layer comprises a p-GaN layer, an MQW layer and an n-GaN layer arranged in sequence from bottom to top, the mesas of the bonding metal layer, the ITO current expansion layer and the first reflector layer are arranged in an I-shaped shape with the mesas of the bonding metal layer, the ITO current expansion layer and the first reflector layer becoming smaller in sequence, the mesas of the gallium nitride epitaxial layer being no larger than the ITO current expansion layer, and a bonding metal layer outside the first reflector layer and the ITO current expansion layer is provided with a bonding metal layer having a bonding metal layer and a bonding metal layer having a bonding metal layer and a bonding metal layer outside the ITO current expansion layer. A metal electrode layer is arranged opposite to the shoulder surface at the bottom of the TO current expansion layer, an insulating layer is deposited on the metal electrode layer and extends to the top of the n-GaN layer, a P-type contact electrode is arranged opposite to the metal electrode layer on the insulating layer on one side of the gallium nitride epitaxial layer, the P-type contact electrode is connected to the p-GaN layer through the metal electrode layer, the ITO current expansion layer to form an ohmic contact conduction, an N-type contact electrode is arranged opposite to the n-GaN layer on the insulating layer on the other side of the gallium nitride epitaxial layer, and a DBR reflector layer is arranged on the n-GaN layer, and the reflectivity of the DBR reflector layer to the light source emitted by the device is lower than that of the first reflector layer.

[0007] A method for preparing a Micro-RCLED device based on an ITO shoulder structure comprises the following steps:

[0008] S1. Growing a u-GaN layer, an n-GaN layer, an MQW layer and a p-GaN layer in sequence from bottom to top on a sapphire substrate to form a sapphire gallium nitride epitaxial wafer;

[0009] S2, growing a transparent ITO film on the p-GaN layer of the sapphire gallium nitride epitaxial wafer as an ITO current spreading layer;

[0010] S3, using a negative photolithography stripping method, and preparing a first reflector layer having a mesa size smaller than the mesa size of the final device on the ITO current spreading layer by EB or magnetron;

[0011] S4, forming a protective mask on the outer surface of the first reflector layer by positive photolithography, preparing the edge shoulder of the ITO current spreading layer by dry or wet etching, and ensuring that the table sizes of the sapphire gallium nitride epitaxial wafer, the ITO current spreading layer, and the first reflector layer are successively smaller;

[0012] S5. Filling a metal electrode layer on the sapphire gallium nitride epitaxial wafer outside the first reflector layer by a negative resist photolithography stripping method, and ensuring that the metal electrode layer is in contact with the patterned ITO current spreading layer shoulder surface to form an ohmic contact;

[0013] S6, sequentially preparing a bonding metal layer and a substrate layer on the metal electrode layer and the first reflector layer from bottom to top to form a first part;

[0014] S7, inverting the first part so that the sapphire gallium nitride epitaxial wafer is on top; peeling off the sapphire substrate by laser peeling or chemical etching peeling; removing the u-GaN layer quickly and precisely by CMP-ICP-CMP hybrid thinning process, and thinning the n-GaN layer to a designed thickness;

[0015] S8. Dry etching with a positive photoresist mask is performed to completely etch the n-GaN layer, the MQW layer, and the p-GaN layer to the metal electrode layer, so that the n-GaN layer, the MQW layer, and the p-GaN layer form a convex platform-shaped gallium nitride epitaxial layer on the metal electrode layer, and ensure that the platform size of the gallium nitride epitaxial layer is not larger than the ITO current spreading layer;

[0016] S9, depositing an insulating layer extending toward the top of the n-GaN layer on the metal electrode layer; after positive photolithography, using dry etching to remove the electrode and the insulating layer at the top light output position, and sequentially evaporating a P-type contact electrode and an N-type contact electrode, so that the P-type contact electrode is in contact with the metal electrode layer, and the N-type contact electrode is in contact with the n-GaN layer;

[0017] S10, preparing a DBR reflector layer on the n-GaN layer, the DBR reflector layer is a DBR reflector.

[0018] In step S2, the first reflector layer is a DBR reflector, and the DBR material is two film systems among TiO2, SiO2, Ta2O5, and SiN, and the number is 10-20 pairs;

[0019] In step S2 , the first reflector layer is a metal reflector and is made of metal AG or AL.

[0020] In step S4, the electrode system of the metal electrode layer is Cr / Al / Ti / Pt / Ti / Pt / Au, which serves as a filling metal while ensuring good electrical properties.

[0021] In step S6 , the bonding metal layer is made of Ni / Sn or Sn / Au, and the substrate layer is made of Si or metal Cu, Al.

[0022] In step S9, the extended insulating layer is an insulating transparent film made of SiO2 or SiN, the metal system of the P-type contact electrode is Ni / Au, and the metal system of the N-type contact electrode is Ti / Al / Ti / Au.

[0023] In step S10, the DBR material of the DBR reflector layer is two film systems with high and low refractive index differences among TiO2, SiO2, Ta2O5, and SiN, and the number is 3-8 pairs.

[0024] In step S7, the specific steps of the CMP-ICP-CMP hybrid thinning process are: 1. Rapidly polish the surface by CMP; 2. Rapidly corrode and remove the u-GaN layer and thin the n-GaN layer by ICP dry etching; 3. Obtain a smooth surface by secondary CMP polishing.

[0025] Compared with the prior art, the present invention has the following advantages:

[0026] 1. The P-type contact electrode contacts the p-GaN layer through the metal electrode layer and the ITO current expansion layer. At the same time, the device table is set to be no larger than the size of the ITO current expansion layer, and the electrical contact is fully optimized. The gallium nitride epitaxial layer in other areas is completely etched, so that all devices can complete the electrical contact of the p-GaN layer through the ITO shoulder structure, avoiding device insulation caused by the inability to accurately etch the p-GaN layer. At the same time, the current injection intensity can be increased by adjusting the shoulder contact area of ​​the ITO current expansion and metal electrode layer, thereby improving the yield and electrical performance of Micro-RCLED devices.

[0027] 2. The DBR reflector layer at the top, the GaN epitaxial layer in the middle and the first reflector layer at the bottom form a Fabry-Perot resonant cavity, so that the light emitted by the active area MQW, after resonance, produces an optimization effect of reducing the divergence angle, improving the device Lambertian distribution, and reducing the half-height width of the luminescence spectrum.

[0028] 3. The commonly used single-step CMP chemical mechanical polishing method, due to the high stress on the two sides of the wafer and low stress in the middle, and the polishing liquid first flows from the edge of the sample and then into the middle, which will cause more thinning at the edge and less thinning in the middle. Therefore, the GAN layer at the edge often falls off, and the thickness of the middle GAN layer has not been thinned to the required thickness (GAN epitaxial layer, the industry is usually 4-6um thick, of which P-GAN is 100-200nm, MQWs is about 50nm, n-GaN is 1-3um, and there is 1-3um for u-GAN growth buffer zone). The film layer at the edge and the center area has a huge difference in thickness, and it is impossible to accurately guarantee the thickness control of the surface GaN film system, which makes the performance of the prepared RC Micro-LED unstable. The present invention adopts a CMP-ICP-CMP hybrid thinning process. After the first CMP rapid polishing is performed to flatten the surface, the u-GAN is quickly etched away and the n-GAN thickness is thinned by the ICP scheme. The n-GaN layer thinning thickness (the thickness error can be controlled within 100nm) and the thinning rate can be accurately controlled. After etching, a secondary CMP polishing is performed to control the surface roughness and meet the subsequent surface process requirements, thereby effectively improving the manufacturing accuracy and performance control of the Micro-RCLED device.

[0029] 4. Since dry etching is difficult to etch the metal electrode layer, it can be ensured that all device mesas on the chip can be completely etched to prepare a Micro-RCLED device with a complete diode structure.

[0030] The present invention provides an ITO shoulder in the device for electrode power transmission, and uses CMP-ICP-CMP hybrid high-precision thinning of GaN thickness to meet the thickness requirement of the resonant cavity, thereby greatly improving the yield of Micro-RCLED chips in mass production, reducing the phenomenon of device short circuit caused by etching through or insufficient etching of the GaN device table, and solving the key problem that the thickness of the resonant cavity cannot be accurately controlled due to the uneven thickness of the n-GAN layer thinned by CMP, resulting in unstable device film breakage performance and even device failure, and facilitating the preparation of Micro-RCLEDs of any band. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 It is a schematic diagram of the structure of the Micro-RCLED device based on the ITO shoulder structure in the present invention.

[0032] Figure 2 It is a process flow chart of the preparation method of the present invention.

[0033] The marks and corresponding component names shown in the figure are:

[0034] 1. Substrate layer; 2. Bonding metal layer; 3. First reflector layer; 4. ITO current spreading layer; 5. GaN epitaxial layer; 6. Metal electrode layer; 7. Insulating layer; 8. P-type contact electrode; 9. N-type contact electrode; 10. DBR reflector layer 10; 51. Sapphire substrate; 52. u-GaN layer; 53. n-GaN layer; 54. MQW layer; 55. p-GaN layer. DETAILED DESCRIPTION

[0035] from Figure 1 It can be seen that the Micro-RCLED device based on the ITO shoulder structure of the present invention includes a substrate layer 1, a bonding metal layer 2, a first reflector layer 3, an ITO current spreading layer 4 and a gallium nitride epitaxial layer 5 arranged in sequence from bottom to top, and the gallium nitride epitaxial layer 5 includes a p-GaN layer 55, an MQW layer 54 and an n-GaN layer 53 arranged in sequence from bottom to top. The mesas of the substrate layer 1 and the bonding metal layer 2 are the same and cover the entire wafer. The mesas of the bonding metal layer 2, the ITO current spreading layer 4 and the first reflector layer 3 are arranged in an I-shaped manner. The mesas of the gallium nitride epitaxial layer 5 are not larger than the mesas of the ITO current spreading layer 4; the bonding metal layer 2 outside the first reflector layer 3 and the ITO current spreading layer 4 is filled with a metal electrode layer 6 arranged in contact with the bottom shoulder surface of the ITO current spreading layer 4, and the top surface of the metal electrode layer 6 is arranged flush with the bottom surface of the p-GaN layer 55;

[0036] An insulating layer 7 is deposited on the metal electrode layer 6 and the sidewall of the gallium nitride epitaxial layer 5, and the insulating layer 7 is extended to the top of the n-GaN layer 53;

[0037] A contact electrode is provided on the insulating layer 7, and the contact electrode includes a P-type contact electrode 8 and an N-type contact electrode 9. The P-type contact electrode 8 is arranged on the insulating layer 7 on one side of the gallium nitride epitaxial layer 5, and the bottom of the P-type contact electrode 8 passes through the insulating layer 7 and is in contact with the metal electrode layer 6. The P-type contact electrode 8 is in ohmic contact conduction formed by connecting the metal electrode layer 6, the ITO current spreading layer 4 and the p-GaN layer 55; the N-type contact electrode 9 is provided on the insulating layer 7 on the other side of the gallium nitride epitaxial layer 5, and the top of the N-type contact electrode 9 extends along the insulating layer 7 to the top of the gallium nitride epitaxial layer 5 and then contacts the n-GaN layer 53;

[0038] A DBR reflector layer 10 is disposed on the n-GaN layer 53 . The reflectivity of the DBR reflector layer to the light source emitted by the device is lower than that of the first reflector layer.

[0039] from Figure 2 It can be seen that the method for preparing the Micro-RCLED device based on the ITO shoulder structure of the present invention comprises the following steps:

[0040] S1. On a sapphire substrate 51, a u-GaN layer 52, an n-GaN layer 53, an MQW layer 54 and a p-GaN layer 55 are grown in sequence from bottom to top to form a sapphire gallium nitride epitaxial wafer, wherein the u-GaN layer 52 serves as a buffer layer, and the electrons of the n-GaN layer 53 and the holes of the p-GaN layer 55 are recombined in the MQW layer 54 region as a light-emitting region;

[0041] S2, growing a transparent ITO film on the p-GaN layer 55 of the sapphire gallium nitride epitaxial wafer as an ITO current spreading layer 4 to increase the conductivity;

[0042] S3, using a negative resist photolithography stripping method, and by EB or magnetron, preparing a first reflector layer 3 having a mesa size smaller than that of the final device on the ITO current spreading layer 4;

[0043] S4, forming a protective mask on the outer surface of the first reflector layer 3 by positive photolithography, preparing the edge shoulder of the ITO current spreading layer 4 by dry or wet etching, and ensuring that the table sizes of the sapphire gallium nitride epitaxial wafer, the ITO current spreading layer 4, and the first reflector layer 3 are successively smaller;

[0044] S5, filling a metal electrode layer 6 on the sapphire gallium nitride epitaxial wafer outside the first reflector layer 3 by a negative resist photolithography stripping method, and ensuring that the metal electrode layer 6 is in contact with the shoulder surface of the patterned ITO current spreading layer 4 to form an ohmic contact;

[0045] S6, sequentially preparing a bonding metal layer (2) and a substrate layer 1 on the metal electrode layer 6 and the first reflector layer 3 from bottom to top to form a first part;

[0046] S7, invert the first part so that the sapphire gallium nitride epitaxial wafer is on top; remove the sapphire substrate 51 by laser stripping or chemical etching stripping; remove the u-GaN layer 52 quickly and accurately by CMP-ICP-CMP hybrid thinning process, and thin the n-GaN layer 53 to a designed thickness, which is flexibly selected according to the design effect strength of the resonant cavity;

[0047] S8, using a positive photoresist mask and dry etching, the n-GaN layer 53, the MQW layer 54 and the p-GaN layer 55 are completely etched through to the metal electrode layer 6, so that the n-GaN layer 53, the MQW layer 54 and the p-GaN layer 55 form a convex platform-shaped gallium nitride epitaxial layer 5 on the metal electrode layer 6, and ensure that the platform size of the gallium nitride epitaxial layer 5 is not larger than the ITO current spreading layer 4;

[0048] S9, depositing an insulating layer 7 extending toward the top of the n-GaN layer 53 on the metal electrode layer 6; after positive photolithography, using dry etching to remove the electrode and the insulating layer 7 at the top light exiting position, and sequentially evaporating a P-type contact electrode 8 and an N-type contact electrode 9, so that the P-type contact electrode 8 is in contact with the metal electrode layer 6, and the N-type contact electrode 9 is in contact with the n-GaN layer 53;

[0049] S10 , preparing a DBR reflector layer 10 on the n-GaN layer 53 , wherein the DBR reflector layer 10 is a DBR reflector.

[0050] In step S2 of the present invention, the first reflector layer 3 is a DBR reflector, and the DBR material is two film systems selected from TiO2, SiO2, Ta2O5, and SiN, and the number is 10-20 pairs.

[0051] In step S2 of the present invention, the first reflector layer 3 is a metal reflector and is made of metal AG or AL.

[0052] In step S4 of the present invention, the electrode system of the metal electrode layer 6 is Cr / Al / Ti / Pt / Ti / Pt / Au.

[0053] In step S6 of the present invention, the bonding metal layer 2 is made of Ni / Sn or Sn / Au, and the substrate layer 1 is made of Si or metal Cu, Al.

[0054] In step S9 of the present invention, the extended insulating layer 7 is an insulating transparent film made of SiO2 or SiN, the metal system of the P-type contact electrode 8 is Ni / Au, and the metal system of the N-type contact electrode 9 is Ti / Al / Ti / Au.

[0055] In step S10 of the present invention, the DBR material of the DBR reflector layer 10 is two film systems with high and low refractive index differences among TiO2, SiO2, Ta2O5, and SiN, and the number is 3-8 pairs.

[0056] In step S7 of the present invention, the specific steps of the CMP-ICP-CMP hybrid thinning process are: 1. Rapidly polishing the surface of the u-GaN layer 52 by CMP; 2. High-precision and rapid etching to remove the u-GaN layer 52 by ICP dry etching, and thinning the n-GaN layer 53 to a designed thickness; 3. Obtaining a smooth surface of the n-GaN layer 53 by secondary CMP polishing.

[0057] The present invention realizes precise control of the thickness of the GaN light-emitting region of the Micro-RCLED by sequentially integrating the ITO shoulder structure, the FP resonant cavity structure composed of the upper and lower reflectors, the contact conductive mode of the metal electrode layer 6 at the bottom of the device and the ITO current expansion layer 4 shoulder structure, substrate transfer, and CMP-ICP-CMP mixed high-precision thinning process in the resonant cavity Micro-RCLED device structure. Compared with the existing Micro-RCLED devices, the device preparation precision control and process yield are greatly improved, and the problems of device insulation and non-conductivity, uneven thickness, and extremely low chip yield are solved when the RC Micro-LED is prepared by the large-size GaN wafer process. The chip yield is greatly improved, and the thickness of the GaN light-emitting layer constituting the middle layer of the resonant cavity is precisely controlled, so as to realize the mass production of Micro-RCLED functional devices with small divergence angle and narrowed spectral half-width.

Claims

1. A Micro-RCLED device based on an ITO shoulder structure, comprising a substrate layer (1), a bonding metal layer (2), a first reflector layer (3), an ITO current spreading layer (4) and a gallium nitride epitaxial layer (5) arranged in sequence from bottom to top, wherein the gallium nitride epitaxial layer comprises a p-GaN layer (55), an MQW layer (54) and an n-GaN layer (53) arranged in sequence from bottom to top, characterized in that: The table sizes of the bonding metal layer, the ITO current expansion layer and the first reflector layer decrease in sequence and are arranged in an I-shaped shape. The table size of the gallium nitride epitaxial layer is not larger than that of the ITO current expansion layer. A metal electrode layer (6) is provided on the bonding metal layer outside the first reflector layer and the ITO current expansion layer and is arranged in contact with the table shoulder surface at the bottom of the ITO current expansion layer. An insulating layer (7) is deposited on the metal electrode layer and is arranged to extend toward the top of the n-GaN layer. A P-type contact electrode (8) is provided on the insulating layer on one side of the gallium nitride epitaxial layer and is in contact with the metal electrode layer. The P-type contact electrode is connected to the p-GaN layer through an ohmic contact conductive manner formed by the metal electrode layer, the ITO current expansion layer and the p-GaN layer. An N-type contact electrode (9) is provided on the insulating layer on the other side of the gallium nitride epitaxial layer and is in contact with the n-GaN layer. A DBR reflector layer (10) is provided on the n-GaN layer. The reflectivity of the DBR reflector layer to the light source emitted by the device is lower than that of the first reflector layer.

2. A method for preparing a Micro-RCLED device based on an ITO shoulder structure according to claim 1, characterized in that: The steps include: S1, growing a u-GaN layer (52), an n-GaN layer (53), an MQW layer (54), and a p-GaN layer (55) in sequence from bottom to top on a sapphire substrate (51) to produce a sapphire gallium nitride epitaxial wafer; S2, growing a transparent ITO film on the p-GaN layer of the sapphire GaN epitaxial wafer as an ITO current spreading layer (4); S3, using a negative resist photolithography stripping method, and by EB or magnetron, preparing a first reflector layer (3) having a mesa size smaller than the mesa size of the final device on the ITO current spreading layer; S4, forming a protective mask on the outer surface of the first reflector layer by positive photolithography, preparing the edge shoulder of the ITO current spreading layer by dry or wet etching, and ensuring that the table sizes of the sapphire gallium nitride epitaxial wafer, the ITO current spreading layer, and the first reflector layer are successively smaller; S5, filling a metal electrode layer (6) on the sapphire gallium nitride epitaxial wafer outside the first reflector layer by a negative resist photolithography stripping method, and ensuring that the metal electrode layer is in contact with the patterned ITO current spreading layer shoulder surface to form an ohmic contact; S6, sequentially preparing a bonding metal layer (2) and a substrate layer (1) on the metal electrode layer and the first reflector layer from bottom to top to form a first part; S7, inverting the first part so that the sapphire gallium nitride epitaxial wafer is on top; peeling off the sapphire substrate by laser peeling or chemical etching peeling; removing the u-GaN layer quickly and precisely by CMP-ICP-CMP hybrid thinning process, and thinning the n-GaN layer to a designed thickness; S8, using a positive photoresist mask and dry etching, the n-GaN layer, the MQW layer and the p-GaN layer are completely etched through to the metal electrode layer, so that the n-GaN layer, the MQW layer and the p-GaN layer form a convex platform-shaped gallium nitride epitaxial layer (5) on the metal electrode layer, and ensure that the platform size of the gallium nitride epitaxial layer is not larger than the ITO current spreading layer; S9, depositing an insulating layer (7) extending toward the top of the n-GaN layer on the metal electrode layer; after positive photolithography, using dry etching to remove the electrode and the insulating layer at the top light output position, and sequentially evaporating a P-type contact electrode (8) and an N-type contact electrode (9) so that the P-type contact electrode is in contact with the metal electrode layer, and the N-type contact electrode is in contact with the n-GaN layer; S10, preparing a DBR reflector layer (10) on the n-GaN layer.

3. The method for preparing a Micro-RCLED device based on an ITO shoulder structure according to claim 2, characterized in that: In step S2, the first reflector layer is a DBR reflector, and the DBR material is two film systems selected from TiO2, SiO2, Ta2O5, and SiN, with a number of 10-20 pairs.

4. The method for preparing a Micro-RCLED device based on an ITO shoulder structure according to claim 2, characterized in that: In step S2 , the first reflector layer is a metal reflector and is made of metal AG or AL.

5. The method for preparing a Micro-RCLED device based on an ITO shoulder structure according to claim 2, characterized in that: In step S4 , the electrode system of the metal electrode layer is Cr / Al / Ti / Pt / Ti / Pt / Au.

6. The method for preparing a Micro-RCLED device based on an ITO shoulder structure according to claim 2, characterized in that: In step S6 , the bonding metal layer is made of Ni / Sn or Sn / Au, and the substrate layer is made of Si or metal Cu, Al.

7. The method for preparing a Micro-RCLED device based on an ITO shoulder structure according to claim 2, characterized in that: In step S9 , the metal system of the P-type contact electrode is Ni / Au, and the metal system of the N-type contact electrode is Ti / Al / Ti / Au.

8. The method for preparing a Micro-RCLED device based on an ITO shoulder structure according to claim 2, characterized in that: In step S10, the DBR material of the DBR reflector layer is two film systems with high and low refractive index differences among TiO2, SiO2, Ta2O5, and SiN, and the number is 3-8 pairs.

9. The method for preparing a Micro-RCLED device based on an ITO shoulder structure according to claim 2, characterized in that: In step S7, the specific steps of the CMP-ICP-CMP hybrid thinning process are:

1. Rapidly polish the surface by CMP; 2. Rapidly corrode and remove the u-GaN layer and thin the n-GaN layer by ICP dry etching; 3. Obtain a smooth surface by secondary CMP polishing.

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