Miniature LED multicolor chip and preparation method thereof

Abstract

According to the miniature LED multi-color chip and the preparation method thereof provided by the invention, the red, green and blue light-emitting units are integrated on the same substrate, so that chips with different colors can be prevented from being transferred to a driving circuit substrate for multiple times, the complexity of a transfer process is simplified, the production efficiency is improved, small-size full-color pixels are convenient to prepare, and the production cost is reduced. And the resolution of the LED display screen can be improved. When the chip array is prepared, the anode contact surface and the cathode contact surface of each light-emitting unit of each full-color pixel are respectively exposed through selective etching, and then the cathode contact surface of each light-emitting unit of each full-color pixel forms common-cathode connection through a metal bonding lamination layer, so that the difficulty of wiring and an integration process is reduced; the method can be easily and directly applied to large-scale production.

Description

Technical Field

[0001] The present invention relates to the technical field of semiconductor devices, and in particular to a micro LED multi-color chip and a preparation method thereof. Background Art

[0002] From the perspective of application scenarios, micro LED is mainly used in direct display and backlighting. Different from micro LED backlighting, micro LED direct display technology uses micro LED multi-color chips directly as display pixels to provide the basic unit of imaging, thereby achieving full-color image display. This technology has the advantages of high brightness, wide color gamut, high contrast, fast response, low power consumption and long life, and is expected to be widely used in high-end LED display fields in the future.

[0003] The full-color micro LED display is made of red, green and blue (RGB) micro LED chips assembled on a driving circuit substrate in a certain arrangement. Due to the small size of micro LED chips, the production of a full-color micro LED display requires three transfers of R / G / B micro LED chips, so its transfer efficiency and device yield will be subject to certain limitations, and there are problems such as the difficulty in reducing the full-color pixel pitch.

[0004] In the prior art, although there is a technical solution for integrating red, green and blue LED structures on one substrate to avoid transferring R / G / B micro LED chips three times, this technical solution has the problem of complex wiring process, which makes this solution unable to be directly applied to large-scale production. Summary of the invention

[0005] Based on this, the purpose of the present invention is to provide a micro LED multi-color chip and a preparation method thereof, so as to solve the problem in the prior art that there is a lack of a preparation method for a micro LED multi-color chip that does not require three transfers and can be mass-produced.

[0006] The present invention provides a method for preparing a micro LED multi-color chip, the preparation method comprising: Providing a substrate, and growing an epitaxial layer on the substrate, wherein the epitaxial layer includes a first light-emitting stack, a second light-emitting stack, and a third light-emitting stack stacked in sequence; Partially etching the epitaxial layer to form a first light-emitting unit, a second light-emitting unit, and a third light-emitting unit, and exposing anode contact surfaces and cathode contact surfaces of the first light-emitting unit, the second light-emitting unit, and the third light-emitting unit; A passivation layer is prepared on the surface of the epitaxial layer, wherein the passivation layer is provided with through holes, and the through holes expose the anode contact surface and the cathode contact surface of the first light-emitting unit, the second light-emitting unit and the third light-emitting unit; A first ohmic contact electrode is prepared at the through hole position of the cathode contact surface of the first light-emitting unit, the second light-emitting unit and the third light-emitting unit, and a second ohmic contact electrode is prepared at the through hole position of the anode contact surface; Metal bonding laminates are prepared on the first ohmic contact electrode and the second ohmic contact electrode respectively, and the first ohmic contact electrodes of the first light emitting unit, the second light emitting unit and the third light emitting unit are connected through the metal bonding laminates.

[0007] Each light emitting unit is a blue light unit, a green light unit or a red light unit, and the color of each unit is different from each other.

[0008] In some embodiments of the present application, the outermost layers of the metal bonding stack are located at the same level.

[0009] In some embodiments of the present application, surfaces of the first light-emitting unit, the second light-emitting unit, and the third light-emitting unit are located at the same horizontal height.

[0010] In some embodiments, the first light emitting unit includes a first light emitting stack, a second light emitting stack, and a third light emitting stack, the second light emitting unit includes a second light emitting stack and a third light emitting stack, and the third light emitting unit includes a third light emitting stack.

[0011] In some embodiments, the first light-emitting stack includes a first N-type semiconductor layer, a first light-emitting layer, and a first P-type semiconductor layer stacked in sequence, the second light-emitting stack includes a second N-type semiconductor layer, a second light-emitting layer, and a second P-type semiconductor layer stacked in sequence, and the third light-emitting stack includes a third N-type semiconductor layer, a third light-emitting layer, and a third P-type semiconductor layer stacked in sequence; the cathode contact surface of the first light-emitting unit, the second light-emitting unit, and the third light-emitting unit is the side of the first N-type semiconductor layer, the second N-type semiconductor layer, and the third N-type semiconductor layer away from the substrate; the anode contact surface of the first light-emitting unit, the second light-emitting unit, and the third light-emitting unit is the side of the first P-type semiconductor layer, the second P-type semiconductor layer, and the third P-type semiconductor layer away from the substrate.

[0012] In some embodiments of the present application, the step of partially etching the epitaxial layer includes: selectively etching the epitaxial layer so that the first light-emitting unit, the second light-emitting unit, and the third light-emitting unit expose the first N-type semiconductor layer, the second N-type semiconductor layer, and the third N-type semiconductor layer, respectively; trenching and etching the first light-emitting unit and the second light-emitting unit so that the first P-type semiconductor layer of the first light-emitting unit is at least partially exposed, and the second P-type semiconductor layer of the second light-emitting unit is at least partially exposed, thereby obtaining a chip array in which the first light-emitting unit, the second light-emitting unit, and the third light-emitting unit are located at the same level.

[0013] In some embodiments, the step of preparing a metal bonding stack on the first ohmic contact electrode includes: using metal deposition technology to form metal bonding stacks on the first ohmic contact electrodes of the first light-emitting unit, the second light-emitting unit, and the third light-emitting unit, respectively, and the first ohmic contact electrodes of the first light-emitting unit, the second light-emitting unit, and the third light-emitting unit are all interconnected through the metal bonding stacks.

[0014] In some embodiments of the present application, the step of preparing a metal bonding stack on the second ohmic contact electrode includes: forming a metal bonding stack on the second ohmic contact electrode of the first light-emitting unit and the third P-type semiconductor layer through a metal deposition technology, forming a metal bonding stack on the second ohmic contact electrode of the second light-emitting unit and the third P-type semiconductor layer, and forming a metal bonding stack on the second ohmic contact electrode of the third light-emitting unit.

[0015] In some embodiments, the material of the metal bonding stack is any one or more combinations of Cr, Pt, In, Sn, and Au.

[0016] The second aspect of the present invention is to provide a micro LED multi-color chip, which is prepared by the preparation method of the micro LED multi-color chip.

[0017] The present invention integrates red, green and blue light-emitting units on the same substrate, thereby avoiding transferring chips of different colors to the drive circuit substrate in multiple times, simplifying the complexity of the transfer process, improving production efficiency, and reducing the spacing between full-color pixels, which is beneficial to improving the resolution of the LED display. When preparing the chip array, the anode contact surface and the cathode contact surface of each light-emitting unit of the full-color pixel are exposed by selective etching, and then the cathode contact surface of each light-emitting unit of the sub-pixel in each full-color pixel is formed into a common cathode connection through a metal bonding laminate, which reduces the difficulty of wiring and integration processes, and is easy to directly apply the present invention to large-scale production. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 This is a schematic diagram of the epitaxial layer grown in the embodiment of the present application.

[0019] Figure 2 This is a schematic diagram of etching the epitaxial layer in an embodiment of the present application.

[0020] Figure 3 This is a schematic diagram of the passivation layer prepared in an embodiment of the present application.

[0021] Figure 4 This is a schematic diagram of the ohmic contact electrode prepared in an embodiment of the present application.

[0022] Figure 5This is a schematic diagram of the preparation of a metal bonding laminate in an embodiment of the present application. DETAILED DESCRIPTION

[0023] In order to facilitate the understanding of the present invention, the present invention will be described more fully below with reference to the relevant drawings. Several embodiments of the present invention are given in the drawings. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present invention more thorough and comprehensive.

[0024] It should be noted that when an element is referred to as being "fixed to" another element, it may be directly on the other element or there may be a central element. When an element is considered to be "connected to" another element, it may be directly connected to the other element or there may be a central element at the same time. The terms "vertical", "horizontal", "left", "right" and similar expressions used herein are for illustrative purposes only.

[0025] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which the present invention belongs. The terms used herein in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more of the related listed items.

[0026] See also Figures 1 to 5 The present application provides a method for preparing a micro LED multi-color chip, the preparation method comprising: Step S1, providing a substrate 100, and growing an epitaxial layer on the substrate, wherein the epitaxial layer includes a first light-emitting stack, a second light-emitting stack, and a third light-emitting stack stacked in sequence.

[0027] In some embodiments of the present application, Figure 1 As shown, the first light-emitting stack includes a first N-type semiconductor layer 121, a first light-emitting layer 122, and a first P-type semiconductor layer 123 stacked in sequence, the second light-emitting stack includes a second N-type semiconductor layer 131, a second light-emitting layer 132, and a second P-type semiconductor layer 133 stacked in sequence, and the third light-emitting stack includes a third N-type semiconductor layer 141, a third light-emitting layer 142, and a third P-type semiconductor layer 143 stacked in sequence. The first light-emitting layer 122, the second light-emitting layer 132, and the third light-emitting layer 142 emit one of blue light, green light, or red light, respectively, and the color of each light-emitting layer is different from each other.

[0028] In some embodiments of the present application, the substrate 100 may be a sapphire substrate or a silicon substrate. Before growing the epitaxial layer, the buffer layer 110 may be grown in an MOCVD system, and the material of the buffer layer 110 may be AlN. The N-type semiconductor layer may be an n-GaN layer, the P-type semiconductor layer may be a p-GaN layer, and the light-emitting layer may be an InGaN / GaN quantum well layer.

[0029] Step S2, partially etching the epitaxial layer to form a first light-emitting unit, a second light-emitting unit and a third light-emitting unit, and exposing the anode contact surface and the cathode contact surface of the first light-emitting unit, the second light-emitting unit and the third light-emitting unit.

[0030] In some embodiments of the present application, the epitaxial layer is partially etched to form the first light-emitting unit, the second light-emitting unit and the third light-emitting unit, and then the first light-emitting unit, the second light-emitting unit and the third light-emitting unit are processed by a preset material removal method, so that the first light-emitting unit, the second light-emitting unit and the third light-emitting unit expose the first N-type semiconductor layer 121, the second N-type semiconductor layer 131 and the third N-type semiconductor layer 141 respectively. The first N-type semiconductor layer 121, the second N-type semiconductor layer 131 and the third N-type semiconductor layer 141 are the cathode contact surfaces of the first light-emitting unit, the second light-emitting unit and the third light-emitting unit. Then, the first light-emitting unit and the second light-emitting unit are grooved and etched to expose at least part of the first P-type semiconductor layer 123 of the first light-emitting unit and at least part of the second P-type semiconductor layer 133 of the second light-emitting unit. The first P-type semiconductor layer 123, the second P-type semiconductor layer 133 and the third P-type semiconductor layer 143 are the anode contact surfaces of the first light-emitting unit, the second light-emitting unit and the third light-emitting unit. Then, the first light-emitting unit, the second light-emitting unit and the third light-emitting unit located at the same level are obtained, and the structure formed is as follows: Figure 2 shown.

[0031] In some embodiments of the present application, the first light-emitting unit includes a first light-emitting stack, a second light-emitting stack and a third light-emitting stack, the second light-emitting unit includes a second light-emitting stack and a third light-emitting stack, and the third light-emitting unit includes a third light-emitting stack.

[0032] It should be noted that by first stacking and growing the light-emitting layers of each color unit on the same substrate, and then obtaining multiple light-emitting units through selective etching, and then removing the color units and light-emitting layers on different light-emitting units respectively as needed, the light-emitting units can control light of different colors.

[0033] Step S3, preparing a passivation layer 150 on the surface of the epitaxial layer, wherein the passivation layer 150 is provided with through holes, and the through holes expose the anode contact surfaces and cathode contact surfaces of the first light-emitting unit, the second light-emitting unit and the third light-emitting unit.

[0034] In some embodiments of the present application, a passivation layer material is first deposited on the surface of the epitaxial layer, and then a through hole is etched by photolithography and wet etching or dry etching to expose the first N-type semiconductor layer 121 and the first P-type semiconductor layer 123 of the first light-emitting unit, the second N-type semiconductor layer 131 and the second P-type semiconductor layer 133 of the second light-emitting unit, and the third N-type semiconductor layer 141 and the third P-type semiconductor layer 143 of the third light-emitting unit. The preparation of the passivation layer 150 is completed, and the structure formed is as follows: Figure 3 shown.

[0035] In some embodiments of the present application, the material of the passivation layer 150 is any one or more combinations of silicon nitride, aluminum nitride, silicon oxide, and aluminum oxide. Alternatively, the material of the passivation layer 150 is an organic curing material, such as polyimide photoresist or SU-8 photoresist.

[0036] Step S4, preparing first ohmic contact electrodes at the through-hole positions of the cathode contact surfaces of the first light-emitting unit, the second light-emitting unit and the third light-emitting unit, and preparing second ohmic contact electrodes at the through-hole positions of the anode contact surfaces.

[0037] In some embodiments of the present application, Figure 4 As shown, metal deposition is performed on the epitaxial layer, and a first cathode electrode 161 is formed on the first N-type semiconductor layer 121 of the first light-emitting unit, and a first anode electrode 171 is formed on the first P-type semiconductor layer 123; a second cathode electrode 162 is formed on the second N-type semiconductor layer 131 of the second light-emitting unit, and a second anode electrode 172 is formed on the second P-type semiconductor layer 133; a third cathode electrode 163 is formed on the third N-type semiconductor layer 141 of the third light-emitting unit, and a third anode electrode 173 is formed on the third P-type semiconductor layer 143. The first light-emitting unit, the first cathode electrode 161 and the first anode electrode 171 constitute a first chip, the second light-emitting unit, the second cathode electrode 162 and the second anode electrode 172 constitute a second chip, and the third light-emitting unit, the third cathode electrode 163 and the third anode electrode 173 constitute a third chip, thereby forming an RGB Mini-LED chip array.

[0038] It should be noted that the first cathode electrode 161 , the second cathode electrode 162 and the third cathode electrode 163 are collectively referred to as first ohmic contact electrodes; the first anode electrode 171 , the second anode electrode 172 and the third anode electrode 173 are collectively referred to as second ohmic contact electrodes.

[0039] Step S5, preparing metal bonding laminates on the first ohmic contact electrode and the second ohmic contact electrode respectively, and connecting the first ohmic contact electrodes of the first light-emitting unit, the second light-emitting unit and the third light-emitting unit through the metal bonding laminates.

[0040] In some embodiments of the present application, Figure 5 As shown, metal deposition is performed on the epitaxial layer to form a first metal bonding stack 181 on the first anode electrode 171 and a portion of the third P-type semiconductor layer 143, a second metal bonding stack 182 on the second anode electrode 172 and a portion of the third P-type semiconductor layer 143, and a third metal bonding stack 183 on the third anode electrode 173. A fourth metal bonding stack 180 is formed on the first cathode electrode 161, the second cathode electrode 162, the third cathode electrode 163 and a portion of the third P-type semiconductor layer 143. The first cathode electrode 161, the second cathode electrode 162 and the third cathode electrode 163 are all connected to each other through the fourth metal bonding stack 180. The topmost layers of the first metal bonding stack 181, the second metal bonding stack 182, the third metal bonding stack 183 and the fourth metal bonding stack 180 are at the same level. The preparation of the micro LED multi-color chip is completed.

[0041] It should be noted that the first metal bonding stack 181 , the second metal bonding stack 182 , the third metal bonding stack 183 and the fourth metal bonding stack 180 are collectively referred to as metal bonding stacks.

[0042] In some embodiments of the present application, the material of the metal bonding laminate is any one or more combinations of Cr, Pt, In, Sn, and Au. Example 1

[0043] See also Figures 1 to 5 This embodiment provides a method for preparing a micro LED multi-color chip, comprising the following steps: Step S1: Figure 1 As shown, a silicon substrate is provided, an AlN buffer layer is grown on the silicon substrate, and an epitaxial layer is grown on the AlN buffer layer, wherein the epitaxial layer includes a blue light stack, a green light stack, and a red light stack stacked in sequence. The blue light stack includes a first N-type semiconductor layer 121, a first light-emitting layer 122, and a first P-type semiconductor layer 123 stacked in sequence, the green light stack includes a second N-type semiconductor layer 131, a second light-emitting layer 132, and a second P-type semiconductor layer 133 stacked in sequence, and the red light stack includes a third N-type semiconductor layer 141, a third light-emitting layer 142, and a third P-type semiconductor layer 143 stacked in sequence.

[0044] The N-type semiconductor layer is an n-GaN layer, the P-type semiconductor layer is a p-GaN layer, and the light-emitting layer is an InGaN / GaN quantum well layer.

[0045] Step S2, partially etching the epitaxial layer to form a blue light unit, a green light unit and a red light unit, and then processing the blue light unit, the green light unit and the red light unit by a preset material removal method, so that the blue light unit, the green light unit and the red light unit expose the first N-type semiconductor layer 121, the second N-type semiconductor layer 131 and the third N-type semiconductor layer 141 respectively. The first N-type semiconductor layer 121, the second N-type semiconductor layer 131 and the third N-type semiconductor layer 141 are the cathode contact surfaces of the blue light unit, the green light unit and the red light unit. Then, trenching and etching are performed on the blue light unit and the green light unit to partially expose the first P-type semiconductor layer 123 of the blue light unit and partially expose the second P-type semiconductor layer 133 of the green light unit. The first P-type semiconductor layer 123, the second P-type semiconductor layer 133 and the third P-type semiconductor layer 143 are the anode contact surfaces of the blue light unit, the green light unit and the red light unit. Then, the blue light unit, green light unit and red light unit at the same level are obtained, and the structure formed is as follows: Figure 2 shown.

[0046] The blue light unit includes a blue light stack, a green light stack and a red light stack, the green light unit includes a green light stack and a red light stack, and the red light unit only includes a red light stack.

[0047] Step S3, deposit silicon dioxide on the surface of the epitaxial layer, and then etch through holes by photolithography and wet etching to expose the first N-type semiconductor layer 121 and the first P-type semiconductor layer 123 of the blue light unit, the second N-type semiconductor layer 131 and the second P-type semiconductor layer 133 of the green light unit, and the third N-type semiconductor layer 141 and the third P-type semiconductor layer 143 of the red light unit. The preparation of the passivation layer 150 is completed, and the structure formed is as shown Figure 3 shown.

[0048] Step S4: Figure 4 As shown, metal deposition is performed on the epitaxial layer to form a first cathode electrode 161 on the first N-type semiconductor layer 121 of the blue light unit, and a first anode electrode 171 on the first P-type semiconductor layer 123; a second cathode electrode 162 is formed on the second N-type semiconductor layer 131 of the green light unit, and a second anode electrode 172 is formed on the second P-type semiconductor layer 133; a third cathode electrode 163 is formed on the third N-type semiconductor layer 141 of the red light unit, and a third anode electrode 173 is formed on the third P-type semiconductor layer 143. The first light-emitting unit, the first cathode electrode 161 and the first anode electrode 171 constitute a first chip, the second light-emitting unit, the second cathode electrode 162 and the second anode electrode 172 constitute a second chip, and the third light-emitting unit, the third cathode electrode 163 and the third anode electrode 173 constitute a third chip, thereby forming an RGB Mini-LED chip array.

[0049] Step S5: Figure 5As shown, metal Au is deposited to form a first metal bonding laminate 181 on the first anode electrode 171 and a portion of the third P-type semiconductor layer 143, a second metal bonding laminate 182 on the second anode electrode 172 and a portion of the third P-type semiconductor layer 143, and a third metal bonding laminate 183 on the third anode electrode 173. A first metal bonding laminate 180 is formed on the first cathode electrode 161, the second cathode electrode 162, the third cathode electrode 163 and a portion of the third P-type semiconductor layer 143. The first cathode electrode 161, the second cathode electrode 162 and the third cathode electrode 163 are all connected to each other through the fourth metal bonding laminate 180. The outermost layers of the first metal bonding laminate 181, the second metal bonding laminate 182, the third metal bonding laminate 183 and the fourth metal bonding laminate 180 are on the same horizontal plane.

[0050] The micro LED multicolor chip prepared in this embodiment is as follows Figure 5 As shown, the micro LED multi-color chip is a full-color chip, characterized by the blue light unit, green light unit and red light unit in the RGB Mini-LED chip array, which are located at the same height without step difference. The topmost layer of the metal bonding stack of all chips will be at the same level, so that the subsequent packaging of the chip array and the formation of electrical connections are simpler and more reliable. By integrating the first chip, the second chip and the third chip on the same substrate, the blue, green and red colors of light are controlled by the first chip, the second chip and the third chip respectively.

[0051] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0052] The above-mentioned embodiments only express several implementation methods of the present invention, and the description thereof is relatively specific and detailed, but it cannot be understood as limiting the scope of the patent of the present invention. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A method for preparing a micro LED multi-color chip, characterized in that: The preparation method comprises: Providing a substrate, and growing an epitaxial layer on the substrate, wherein the epitaxial layer comprises a first light-emitting stack, a second light-emitting stack, and a third light-emitting stack stacked in sequence; Partially etching the epitaxial layer to form a first light-emitting unit, a second light-emitting unit, and a third light-emitting unit, and exposing anode contact surfaces and cathode contact surfaces of the first light-emitting unit, the second light-emitting unit, and the third light-emitting unit; A passivation layer is prepared on the surface of the epitaxial layer, wherein the passivation layer is provided with through holes, wherein the through holes expose the anode contact surface and the cathode contact surface of the first light-emitting unit, the second light-emitting unit and the third light-emitting unit; A first ohmic contact electrode is prepared at the through hole position of the cathode contact surface of the first light-emitting unit, the second light-emitting unit and the third light-emitting unit, and a second ohmic contact electrode is prepared at the through hole position of the anode contact surface; Preparing metal bonding laminates on the first ohmic contact electrode and the second ohmic contact electrode respectively, and the first ohmic contact electrodes of the first light-emitting unit, the second light-emitting unit and the third light-emitting unit are connected through the metal bonding laminates; Each of the light emitting units is a blue light unit, a green light unit or a red light unit, and the colors of each unit are different.

2. The method for preparing a micro LED multicolor chip according to claim 1, characterized in that: The outermost layers of the metal bonding laminate are located at the same level.

3. The method for preparing a micro LED multicolor chip according to claim 1, characterized in that: Surfaces of the first light emitting unit, the second light emitting unit and the third light emitting unit are located at the same horizontal height.

4. The method for preparing a micro LED multicolor chip according to claim 3, characterized in that: The first light emitting unit includes a first light emitting stack, a second light emitting stack and a third light emitting stack, the second light emitting unit includes a second light emitting stack and a third light emitting stack, and the third light emitting unit includes a third light emitting stack.

5. The method for preparing a micro LED multi-color chip according to claim 1, characterized in that: The first light-emitting stack comprises a first N-type semiconductor layer, a first light-emitting layer and a first P-type semiconductor layer stacked in sequence, the second light-emitting stack comprises a second N-type semiconductor layer, a second light-emitting layer and a second P-type semiconductor layer stacked in sequence, and the third light-emitting stack comprises a third N-type semiconductor layer, a third light-emitting layer and a third P-type semiconductor layer stacked in sequence; The cathode contact surface of the first light-emitting unit, the second light-emitting unit and the third light-emitting unit is the side of the first N-type semiconductor layer, the second N-type semiconductor layer and the third N-type semiconductor layer away from the substrate; the anode contact surface of the first light-emitting unit, the second light-emitting unit and the third light-emitting unit is the side of the first P-type semiconductor layer, the second P-type semiconductor layer and the third P-type semiconductor layer away from the substrate.

6. The method for preparing a micro LED multicolor chip according to claim 5, characterized in that: The step of partially etching the epitaxial layer comprises: Selectively etching the epitaxial layer so that the first light-emitting unit, the second light-emitting unit and the third light-emitting unit expose the first N-type semiconductor layer, the second N-type semiconductor layer and the third N-type semiconductor layer respectively; The first light-emitting unit and the second light-emitting unit are grooved and etched to expose at least partially the first P-type semiconductor layer of the first light-emitting unit and to expose at least partially the second P-type semiconductor layer of the second light-emitting unit, thereby obtaining a chip array in which the first light-emitting unit, the second light-emitting unit and the third light-emitting unit are located at the same level.

7. The method for preparing a micro LED multicolor chip according to claim 1, characterized in that: The step of preparing a metal bonding laminate on the first ohmic contact electrode comprises: Through metal deposition technology, metal bonding stacks are formed on the first ohmic contact electrodes of the first light-emitting unit, the second light-emitting unit and the third light-emitting unit, respectively, and the first ohmic contact electrodes of the first light-emitting unit, the second light-emitting unit and the third light-emitting unit are all interconnected through the metal bonding stacks.

8. The method for preparing a micro LED multicolor chip according to claim 5, characterized in that: The step of preparing a metal bonding laminate on the second ohmic contact electrode comprises: Through metal deposition technology, a metal bonding stack is formed on the second ohmic contact electrode of the first light-emitting unit and the third P-type semiconductor layer, a metal bonding stack is formed on the second ohmic contact electrode of the second light-emitting unit and the third P-type semiconductor layer, and a metal bonding stack is formed on the second ohmic contact electrode of the third light-emitting unit.

9. The method for preparing a micro LED multicolor chip according to claim 1, characterized in that: The material of the metal bonding laminate is any one or more combinations of Cr, Pt, In, Sn and Au.

10. A micro LED multi-color chip, characterized in that: The micro LED multi-color chip is prepared by the preparation method of the micro LED multi-color chip according to any one of claims 1 to 6.

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