RGB three-primary-color Micro LED epitaxial wafer and preparation method thereof

Abstract

The invention discloses an RGB three-primary-color Micro LED epitaxial wafer and a preparation method thereof, and relates to the technical field of semiconductor devices, and the method comprises the steps: depositing a buffer layer on a substrate; stacking a first epitaxial material on the buffer layer, and forming a first epitaxial layer at a first position in each light-emitting unit; depositing a first protective layer on the surface of the first epitaxial layer; stacking a second epitaxial layer on the buffer layer at a second position, wherein the second position is adjacent to the first position; depositing a second protection layer on the surfaces of the first protection layer and the second epitaxial layer; the buffer layer is etched to expose the surface of the substrate, a third epitaxial layer is stacked on the substrate at a third position, and the third position is adjacent to the second position; and removing the first protection layer and the second protection layer to obtain the RGB three-primary-color Micro LED epitaxial wafer. According to the invention, the manufacturing cost of the epitaxial wafer is reduced by carrying out epitaxial manufacturing on the RGB three-primary-color Micro LED epitaxial wafer.

Description

Technical Field

[0001] The present invention relates to the technical field of semiconductor devices, and in particular to an RGB three-primary-color Micro LED epitaxial wafer and a preparation method thereof. Background Art

[0002] Micro LED micro-display technology has the characteristics of self-luminescence. Each pixel can be driven to emit light independently. Its advantages include high brightness, low power consumption, small size, ultra-high resolution and color saturation. Compared with OLED technology, which is also a self-luminous display, Micro LED is not only more efficient and has a longer lifespan, but also has relatively stable materials that are not easily affected by the environment, and can also avoid the phenomenon of afterimage.

[0003] The current common technology for Micro display is to use a set of light-emitting units composed of RGB three-primary color wafer chips, peel off the RGB three-primary color wafer substrates separately, and then transfer them to the substrate in large quantities.

[0004] In the above technology, all wafers are monochrome wafers, and the substrates of the three-primary-color wafers need to be peeled off, that is, they need to be peeled off three times, and the mass transfer also needs to be transferred three times, which greatly increases the production cost. Summary of the invention

[0005] In view of the deficiencies in the prior art, the object of the present invention is to provide an RGB three-primary color Micro LED epitaxial wafer and a preparation method thereof, aiming to reduce the production cost of the epitaxial wafer by performing epitaxial production on the RGB three-primary color Micro LED epitaxial wafer.

[0006] A first aspect of the present invention is to provide a method for preparing an RGB three-primary color Micro LED epitaxial wafer, the preparation method comprising: providing a substrate, and depositing a buffer layer on the substrate; Build up a first epitaxial material on the buffer layer, etch the first epitaxial material to expose the surface of the buffer layer, and form a first epitaxial layer at a first position in each light-emitting unit; depositing a first protective layer on a surface of the first epitaxial layer; In each of the light-emitting units, a second epitaxial layer is grown on the buffer layer at a second position, the second position being adjacent to the first position; Depositing a second protective layer on the surfaces of the first protective layer and the second epitaxial layer; In each of the light-emitting units, the buffer layer is etched to expose the surface of the substrate, and a third epitaxial layer is grown on the substrate at a third position, wherein the third position is adjacent to the second position; The first protective layer and the second protective layer are removed to obtain an RGB three-primary color Micro LED epitaxial wafer.

[0007] According to one aspect of the above technical solution, the first epitaxial layer, the second epitaxial layer and the third epitaxial layer are a blue epitaxial layer, a green epitaxial layer and a red epitaxial layer respectively.

[0008] According to one aspect of the above technical solution, the step of depositing a first protective layer on the surface of the first epitaxial layer includes: Depositing a first protective material on the surface of the buffer layer, so that the first protective material wraps the first epitaxial layer at the first position, and covers the buffer layer at the second position and the third position; Photolithography and wet etching are used to remove the first protective material on the surface of the buffer layer at the second position and the third position to obtain a plurality of first protective layers respectively covering the surface of the first epitaxial layer in each light-emitting unit.

[0009] According to one aspect of the above technical solution, the step of depositing a second protective layer on the surfaces of the first protective layer and the second epitaxial layer includes: Depositing a second protective material on the surface of the buffer layer, so that the second protective material includes a first protective layer located at a first position, a second epitaxial layer located at a second position, and covers the buffer layer located at a third position; The second protective material on the surface of the buffer layer at the third position is removed by photolithography and wet etching to obtain a plurality of second protective layers respectively covering the surfaces of the first protective layer and the second epitaxial layer in each light-emitting unit.

[0010] According to one aspect of the above technical solution, the thickness of the first epitaxial layer is equal to that of the second epitaxial layer.

[0011] According to one aspect of the above technical solution, the thickness of the third epitaxial layer is equal to the sum of the thicknesses of the first epitaxial layer, the second epitaxial layer and the buffer layer.

[0012] According to one aspect of the above technical solution, the substrate is made of GaAs material with a thickness of 300 μm-600 μm; The buffer layer is made of AlN material and has a thickness of 100Å-5000Å.

[0013] According to one aspect of the above technical solution, the first protective material used to make the first protective layer and the second protective material used to make the second protective layer are both SiO 2 、SiN X 、TiO 2 、Al 2 O 3 , any one of AlN materials.

[0014] The second aspect of the present invention is to provide an RGB three-primary color Micro LED epitaxial wafer, which is prepared by the preparation method described in the above technical solution, and the epitaxial wafer comprises: substrate; a buffer layer disposed on the substrate and exposing a surface of the substrate at a third position; a first epitaxial layer, located on the buffer layer at a first position in each light-emitting unit; a second epitaxial layer, located on the buffer layer at the second position in each light-emitting unit; a third epitaxial layer located on the substrate at a third position in each light emitting unit; Wherein, in each light-emitting unit, the first position, the second position and the third position are arranged linearly, and the first epitaxial layer, the second epitaxial layer and the third epitaxial layer are arranged linearly.

[0015] According to one aspect of the above technical solution, the first epitaxial layer, the second epitaxial layer and the third epitaxial layer are a blue epitaxial layer, a green epitaxial layer and a red epitaxial layer respectively.

[0016] Compared with the prior art, the RGB three-primary color Micro LED epitaxial wafer and the preparation method thereof shown in the present invention have the following beneficial effects: The present invention provides a substrate, deposits a buffer layer on the substrate, crystallizes a first epitaxial material on the buffer layer, etches the first epitaxial material to expose the surface of the buffer layer, forms a first epitaxial layer at a first position in each light-emitting unit, deposits a first protective layer on the surface of the first epitaxial layer, and in each light-emitting unit, crystallizes a second epitaxial layer on the buffer layer at a second position, the second position is adjacent to the first position, and deposits a second protective layer on the surface of the first protective layer and the second epitaxial layer. In each light-emitting unit, the buffer layer is etched to expose the surface of the substrate, and a third epitaxial layer is crystallized on the substrate at a third position, the third position is adjacent to the second position, and the first protective layer and the second protective layer are removed to obtain an RGB three-primary color Micro LED epitaxial wafer. The present invention can obtain an RGB three-primary color Micro LED epitaxial wafer by separately manufacturing RGB three-primary color epitaxial layers on the same substrate without substrate peeling and corresponding mass transfer of a single-primary color wafer, thereby reducing the manufacturing cost of the epitaxial wafer and improving the manufacturing efficiency of the epitaxial wafer. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The above and / or additional aspects and advantages of the present invention will become apparent and easily understood from the description of the embodiments in conjunction with the following drawings, in which: Figure 1Schematic diagram of the process of preparing a RGB tri-primary color Micro LED epitaxial wafer in one embodiment of the present invention; Figure 2 Schematic diagram of the manufacturing process of RGB tri-primary color Micro LED epitaxial wafer in one embodiment of the present invention; Figure 3 This is a schematic diagram of the structure of an RGB three-primary color Micro LED epitaxial wafer in one embodiment of the present invention; Component symbol description: The substrate 10 , the buffer layer 20 , the first epitaxial layer 31 , the first protective layer 40 , the second epitaxial layer 50 , the second protective layer 60 , and the third epitaxial layer 70 . DETAILED DESCRIPTION

[0018] In order to make the purpose, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are described in detail below in conjunction with the accompanying drawings. Several embodiments of the present invention are shown in the accompanying 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.

[0019] 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.

[0020] 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.

[0021] A first aspect of the present invention provides a method for preparing an RGB tri-primary color Micro LED epitaxial wafer, the method comprising: providing a substrate, and depositing a buffer layer on the substrate; Build up a first epitaxial material on the buffer layer, etch the first epitaxial material to expose the surface of the buffer layer, and form a first epitaxial layer at a first position in each light-emitting unit; depositing a first protective layer on a surface of the first epitaxial layer; In each of the light-emitting units, a second epitaxial layer is grown on the buffer layer at a second position, the second position being adjacent to the first position; Depositing a second protective layer on the surfaces of the first protective layer and the second epitaxial layer; In each of the light-emitting units, the buffer layer is etched to expose the surface of the substrate, and a third epitaxial layer is grown on the substrate at a third position, wherein the third position is adjacent to the second position; The first protective layer and the second protective layer are removed to obtain an RGB three-primary color Micro LED epitaxial wafer.

[0022] Furthermore, the first epitaxial layer, the second epitaxial layer and the third epitaxial layer are a blue epitaxial layer, a green epitaxial layer and a red epitaxial layer respectively.

[0023] Furthermore, the step of depositing a first protective layer on the surface of the first epitaxial layer includes: Depositing a first protective material on the surface of the buffer layer, so that the first protective material wraps the first epitaxial layer at the first position, and covers the buffer layer at the second position and the third position; Photolithography and wet etching are used to remove the first protective material on the surface of the buffer layer at the second position and the third position to obtain a plurality of first protective layers respectively covering the surface of the first epitaxial layer in each light-emitting unit.

[0024] Furthermore, the step of depositing a second protective layer on the surface of the first protective layer and the second epitaxial layer includes: Depositing a second protective material on the surface of the buffer layer, so that the second protective material includes a first protective layer located at a first position, a second epitaxial layer located at a second position, and covers the buffer layer located at a third position; The second protective material on the surface of the buffer layer at the third position is removed by photolithography and wet etching to obtain a plurality of second protective layers respectively covering the surfaces of the first protective layer and the second epitaxial layer in each light-emitting unit.

[0025] Furthermore, the first epitaxial layer and the second epitaxial layer have the same thickness.

[0026] Furthermore, the thickness of the third epitaxial layer is equal to the sum of the thicknesses of the first epitaxial layer, the second epitaxial layer and the buffer layer.

[0027] Furthermore, the substrate is made of GaAs material and has a thickness of 300 μm-600 μm; The buffer layer is made of AlN material and has a thickness of 100Å-5000Å.

[0028] Furthermore, the first protective material used to make the first protective layer and the second protective material used to make the second protective layer are both SiO 2 、SiN X 、TiO 2 、Al 2 O 3 , any one of AlN materials.

[0029] The second aspect of the present invention provides an RGB three-primary color Micro LED epitaxial wafer, which is prepared by the preparation method described in the above technical solution, and the epitaxial wafer comprises: substrate; a buffer layer disposed on the substrate and exposing a surface of the substrate at a third position; a first epitaxial layer, located on the buffer layer at a first position in each light-emitting unit; a second epitaxial layer, located on the buffer layer at the second position in each light-emitting unit; a third epitaxial layer located on the substrate at a third position in each light emitting unit; Wherein, in each light-emitting unit, the first position, the second position and the third position are arranged linearly, and the first epitaxial layer, the second epitaxial layer and the third epitaxial layer are arranged linearly.

[0030] Furthermore, the first epitaxial layer, the second epitaxial layer and the third epitaxial layer are a blue epitaxial layer, a green epitaxial layer and a red epitaxial layer respectively.

[0031] Compared with the prior art, the RGB three-primary color Micro LED epitaxial wafer and the preparation method thereof shown in the present invention have the following beneficial effects: The present invention provides a substrate, deposits a buffer layer on the substrate, crystallizes a first epitaxial material on the buffer layer, etches the first epitaxial material to expose the surface of the buffer layer, forms a first epitaxial layer at a first position in each light-emitting unit, deposits a first protective layer on the surface of the first epitaxial layer, and in each light-emitting unit, crystallizes a second epitaxial layer on the buffer layer at a second position, the second position is adjacent to the first position, and deposits a second protective layer on the surface of the first protective layer and the second epitaxial layer. In each light-emitting unit, the buffer layer is etched to expose the surface of the substrate, and a third epitaxial layer is crystallized on the substrate at a third position, the third position is adjacent to the second position, and the first protective layer and the second protective layer are removed to obtain an RGB three-primary color Micro LED epitaxial wafer. The present invention can obtain an RGB three-primary color Micro LED epitaxial wafer by separately manufacturing RGB three-primary color epitaxial layers on the same substrate without substrate peeling and corresponding mass transfer of a single-primary color wafer, thereby reducing the manufacturing cost of the epitaxial wafer and improving the manufacturing efficiency of the epitaxial wafer.

[0032] First embodiment See also Figure 1 and Figure 2 The first embodiment of the present invention provides a method for preparing an RGB tri-color Micro LED epitaxial wafer. The preparation method shown in this embodiment includes steps S10 to S70: Step S10, providing a substrate, and depositing a buffer layer on the substrate.

[0033] In this embodiment, the substrate 10 is a GaAs substrate, i.e., a gallium arsenide substrate, and the thickness of the substrate 10 is 500 μm. The substrate 10 is pretreated, including cleaning, drying, etc., so as to obtain a substrate 10 with high cleanliness, and then a buffer layer 20 is deposited on the substrate 10. The buffer layer 20 is made of AlN material, which is a crystalline material, and the thickness of the buffer layer 20 is 2000 Å.

[0034] In some feasible embodiments, the thickness of the substrate 10 may be 300 μm-600 μm, and the thickness of the buffer layer 20 may be 100 Å-5000 Å.

[0035] Step S20 , stacking a first epitaxial material on the buffer layer, etching the first epitaxial material to expose a surface of the buffer layer, and forming a first epitaxial layer at a first position in each light-emitting unit.

[0036] First of all, it should be noted that in this embodiment, by depositing a buffer layer 20 on the substrate 10 and performing epitaxial growth on the buffer layer 20, the buffer layer 20 can provide an intermediate layer between two different materials, thereby improving the interface characteristics between them, reducing defects at the interface, and improving the stability and performance of the overall structure. The buffer layer 20 can also alleviate the stress caused by lattice constant mismatch. This mismatch may lead to the formation of dislocations and other defects, and the buffer layer 20 can reduce these defects in a gradual manner, so that the subsequently deposited film can grow better. And there may be differences in the thermal expansion coefficients between different materials, which will generate stress when the temperature changes. The buffer layer 20 can help adapt to this difference, reduce the stress caused by temperature changes, and thus protect the overall structure from damage. Finally, in some cases, a specific chemical reaction may occur between the two materials, resulting in a decrease in performance at the interface. The buffer layer 20 can play a role in chemical isolation, prevent the occurrence of such reactions, and keep the interface clear and stable.

[0037] In this embodiment, after depositing the buffer layer 20 on the substrate 10, the first epitaxial material is stacked on the buffer layer 20, that is, the first epitaxial material is used for epitaxial growth. At this time, the surface of the buffer layer 20 will be completely covered by the first epitaxial material, and then the first epitaxial material is etched to expose the surface of the buffer layer 20, so that the first epitaxial material can be separated into multiple independent first epitaxial layers 31.

[0038] The etching of the first epitaxial material to expose the surface of the buffer layer 20 has certain position requirements, specifically requiring the first epitaxial layer 31 to be in the first position of each light-emitting unit, and the light-emitting unit may also have a second position, a third position, etc.

[0039] Specifically, etching the first epitaxial material to expose the surface of the buffer layer 20 is equivalent to reserving epitaxial growth regions for multiple light-emitting units on the buffer layer 20, each epitaxial growth region is used for multiple separate epitaxial growths, thereby obtaining mutually independent light-emitting units.

[0040] More specifically, the first epitaxial layer 31 is a blue epitaxial layer with a thickness of 3-10 μm, for example, 5 μm. That is, the epitaxial layer at the first position in each light-emitting unit in this embodiment is a blue epitaxial layer, which will emit blue light after electrochemical reaction.

[0041] At this point, the epitaxial growth of the first epitaxial layer 31 is completed.

[0042] Step S30: depositing a first protective layer on the surface of the first epitaxial layer.

[0043] In this embodiment, the step of depositing a first protective layer on the surface of the first epitaxial layer includes: Depositing a first protective material on the surface of the buffer layer, so that the first protective material wraps the first epitaxial layer at the first position, and covers the buffer layer at the second position and the third position; Photolithography and wet etching are used to remove the first protective material on the surface of the buffer layer at the second position and the third position to obtain a plurality of first protective layers respectively covering the surface of the first epitaxial layer in each light-emitting unit.

[0044] Specifically, after the first epitaxial material is deposited on the buffer layer 20 and multiple first epitaxial layers 31 are obtained by etching, since epitaxial growth of other epitaxial layers is also required, in order to protect the first epitaxial layer 31, in this embodiment, a first protective layer 40 is deposited on the first epitaxial layer 31, and the surface of the first epitaxial layer 31 is protected by the first protective layer 40.

[0045] More specifically, the present embodiment specifically deposits a first protective material on the surface of the buffer layer 20, so that the first protective material wraps the first epitaxial layer 31 located at the first position, and covers the buffer layer 20 located at the second position and the third position, that is, the first protective material is deposited on the semi-finished epitaxial wafer by planar deposition, and then the first protective material on the surface of the buffer layer 20 at the second position and the third position is removed by photolithography and wet etching, and the first protective layer 40 located on the surface of the first epitaxial layer 31 is retained, thereby obtaining the first protective layer 40 covering the surface of the first epitaxial layer 31 in each light-emitting unit respectively.

[0046] The first protective material used to make the first protective layer 40 can be SiO 2 、SiN X 、TiO 2 、Al 2 O 3 , AlN and other insulating materials, such as SiO 2 The first protective layer 40 is made of insulating material. The thickness of the first protective layer 40 covering the surface of the first epitaxial layer 31 is 200nm-3000nm.

[0047] Step S40: In each of the light-emitting units, a second epitaxial layer is grown on the buffer layer at a second position, wherein the second position is adjacent to the first position.

[0048] In this embodiment, after the epitaxial growth of the first epitaxial layer 31 and the production of the first protective layer 40 are completed, the second epitaxial layer 50 is stacked on the buffer layer 20 at the second position of each light-emitting unit, and in each light-emitting unit, the second position is adjacent to the first position.

[0049] Specifically, the second epitaxial layer 50 in this embodiment is a green light epitaxial layer, which will emit green light after an electrochemical reaction. The purpose of arranging the second epitaxial layer 50 as a green light epitaxial layer in the middle of the judge unit is to ensure that the three colors of RGB LED chips can be evenly distributed in the display area, thereby achieving better color performance and more accurate color reproduction.

[0050] At this point, the epitaxial growth of the second epitaxial layer 50 is completed.

[0051] Step S50: depositing a second protective layer on the surfaces of the first protective layer and the second epitaxial layer.

[0052] It should be noted that after the second epitaxial layer 50 is obtained by epitaxial growth, since epitaxial growth of other epitaxial layers is still required, in order to protect the second epitaxial layer 50 and the pre-deposited first protective layer 40, mainly to protect the second epitaxial layer 50 that temporarily lacks protection, in this embodiment, a second protective layer 60 is deposited on the second epitaxial layer 50 and the first protective layer 40, and the surfaces of the second epitaxial layer 50 and the first protective layer 40 are protected by the second protective layer 60.

[0053] In this embodiment, the step of depositing a second protective layer on the surfaces of the first protective layer and the second epitaxial layer includes: Depositing a second protective material on the surface of the buffer layer, so that the second protective material includes a first protective layer located at a first position, a second epitaxial layer located at a second position, and covers the buffer layer located at a third position; The second protective material on the surface of the buffer layer at the third position is removed by photolithography and wet etching to obtain a plurality of second protective layers respectively covering the surfaces of the first protective layer and the second epitaxial layer in each light-emitting unit.

[0054] Specifically, the present embodiment specifically deposits a first protective material on the first protective layer 40, the second epitaxial layer 50 and the buffer layer 20 located at the third position, so that the first protective material wraps the first protective layer 40 located at the first position, the second epitaxial layer 50 located at the second position, and covers the buffer layer 20 located at the third position, that is, the second protective material is deposited on the semi-finished epitaxial wafer by planar deposition, and then the second protective material on the surface of the buffer layer 20 at the third position is removed by photolithography and wet etching, and the second protective layer 60 located on the surfaces of the first protective layer 40 and the second epitaxial layer 50 is retained, thereby obtaining a second protective layer 60 covering the surfaces of the first protective layer 40 and the first epitaxial layer 31 in each light-emitting unit respectively.

[0055] The second protective material used to make the second protective layer 60 can be SiO 2 、SiN X 、TiO 2 、Al 2 O 3 , AlN and other insulating materials. In order to optimize the manufacturing process, the second protective layer 60 is made of the same material as the first protective layer 40, SiO 2 The second protection layer 60 is made of insulating material, and the thickness of the second protection layer 60 is equal to the thickness of the first protection layer 40 .

[0056] Step S60: in each of the light-emitting units, the buffer layer is etched to expose the surface of the substrate, and a third epitaxial layer is grown on the substrate at a third position, wherein the third position is adjacent to the second position.

[0057] In this embodiment, after the second protection layer 60 is deposited, the second protection layer 60 located at the third position is etched to expose the surface of the buffer layer 20 .

[0058] Furthermore, in each light-emitting unit, the buffer layer 20 is etched to expose the surface of the substrate 10, and the third epitaxial layer 70 is stacked on the substrate 10 at the third position, and the third position is adjacent to the second position. In order to optimize the manufacturing process, the second protective layer 60 at the third position and the buffer layer 20 at the bottom thereof can be etched in the same process, and by increasing the etching depth, part of the material of the second protective layer 60 and the buffer layer 20 at the bottom thereof can be removed at the same time, exposing the substrate 10, so as to facilitate the epitaxial growth of the third epitaxial layer 70 on the substrate 10.

[0059] Specifically, the third epitaxial layer 70 is a red light epitaxial layer, which emits red light after undergoing an electrochemical reaction.

[0060] Among them, since the first epitaxial layer 31 and the second epitaxial layer 50 are both epitaxially grown on the buffer layer 20, the thicknesses of the first epitaxial layer 31 and the second epitaxial layer 50 in this embodiment are equal, that is, the thicknesses of the blue light epitaxial layer and the green light epitaxial layer are equal, and since the third epitaxial layer 70 is not epitaxially grown on the buffer layer 20, but is directly epitaxially grown on the substrate 10, the thickness of the third epitaxial layer 70 in this embodiment is equal to the sum of the thicknesses of the first epitaxial layer 31, the second epitaxial layer 50 and the buffer layer 20, that is, the thickness of the red light epitaxial layer is equal to the sum of the thicknesses of the blue light epitaxial layer and the buffer layer 20, and is also equal to the sum of the thicknesses of the green light epitaxial layer and the buffer layer 20, which can make the surfaces of the first epitaxial layer 31, the second epitaxial layer 50 and the third epitaxial layer 70 flush.

[0061] It is worth noting that the third epitaxial layer 70 is grown directly on the substrate 10 instead of on the buffer layer 20. This is because the material system of the third epitaxial layer 70 corresponds to the material system of the substrate 10, and there is no need for transition through the buffer layer 20. Direct epitaxial growth on the buffer layer 20 can increase the volume of the third epitaxial layer 70 and the reaction efficiency of the multi-quantum wells, thereby making the luminescence brightness stronger.

[0062] Step S70, removing the first protective layer and the second protective layer to obtain an RGB three-primary color Micro LED epitaxial wafer.

[0063] In the present embodiment, after the first epitaxial layer 31, the second epitaxial layer 50 and the third epitaxial layer 70 are obtained by epitaxial growth at the first position, the second position and the third position of each light-emitting unit, the blue light epitaxial layer, the green light epitaxial layer and the red light epitaxial layer arranged according to the preset epitaxial arrangement rule in the multiple light-emitting units are obtained, and then the first protective layer 40 and the second protective layer 60 used for protection are removed, for example, by wet etching or laser ablation, and the material removal accuracy is required to be controlled to avoid damaging the first epitaxial layer 31, the second epitaxial layer 50 and the third epitaxial layer 70, and finally the RGB three-primary color Micro LED epitaxial wafer is obtained.

[0064] Among them, the so-called RGB three-primary color Micro LED epitaxial wafer is a Micro LED epitaxial wafer that emits light based on the three primary colors (blue, green, and red). After that, the chip is made to obtain an RGB three-primary color Micro LED chip.

[0065] Using the preparation method shown in this embodiment, a RGB three-primary color Micro LED epitaxial wafer is manufactured. Figure 3 As shown, including: Substrate 10; a buffer layer 20 disposed on the substrate 10 and exposing the surface of the substrate 10 at a third position; A first epitaxial layer 31 is located on the buffer layer 20 at a first position in each light emitting unit; A second epitaxial layer 50 is located on the buffer layer 20 at the second position in each light emitting unit; A third epitaxial layer 70 is located on the substrate 10 at a third position in each light emitting unit; Wherein, in each light-emitting unit, the first position, the second position and the third position are arranged linearly, and the first epitaxial layer 31 , the second epitaxial layer 50 and the third epitaxial layer 70 are arranged linearly.

[0066] In the epitaxial wafer, the first epitaxial layer 31 , the second epitaxial layer 50 and the third epitaxial layer 70 are respectively a blue epitaxial layer, a green epitaxial layer and a red epitaxial layer.

[0067] Compared with the prior art, the RGB three-primary color Micro LED epitaxial wafer and the preparation method thereof shown in the present invention have the following beneficial effects: In this embodiment, a substrate 10 is provided, a buffer layer 20 is deposited on the substrate 10, a first epitaxial material is crystallized on the buffer layer 20, the first epitaxial material is etched to expose the surface of the buffer layer 20, a first epitaxial layer 31 is formed at a first position in each light-emitting unit, a first protective layer 40 is deposited on the surface of the first epitaxial layer 31, and in each light-emitting unit, a second epitaxial layer 50 is crystallized on the buffer layer 20 at a second position, the second position is adjacent to the first position, a second protective layer 60 is deposited on the surface of the first protective layer 40 and the second epitaxial layer 50, in each light-emitting unit, the buffer layer 20 is etched to expose the surface of the substrate 10, a third epitaxial layer 70 is crystallized on the substrate 10 at a third position, the third position is adjacent to the second position, and the first protective layer 40 and the second protective layer 60 are removed to obtain an RGB three-primary color Micro LED epitaxial wafer. In this embodiment, RGB three-primary color epitaxial layers are separately manufactured on the same substrate 10, and there is no need to peel off the substrate 10 of the single-primary color wafer and perform corresponding mass transfer, so that the RGB three-primary color Micro LED epitaxial wafer can be obtained, which reduces the production cost of the epitaxial wafer and improves the production efficiency of the epitaxial wafer.

[0068] 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.

[0069] The above-mentioned embodiments only express several implementation methods of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the patent of the present invention. It should be pointed out that, for those of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present invention, and these 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 an RGB three-primary color Micro LED epitaxial wafer, characterized in that: The preparation method comprises: providing a substrate, and depositing a buffer layer on the substrate; Build up a first epitaxial material on the buffer layer, etch the first epitaxial material to expose the surface of the buffer layer, and form a first epitaxial layer at a first position in each light-emitting unit; depositing a first protective layer on a surface of the first epitaxial layer; In each of the light-emitting units, a second epitaxial layer is grown on the buffer layer at a second position, the second position being adjacent to the first position; Depositing a second protective layer on the surfaces of the first protective layer and the second epitaxial layer; In each of the light-emitting units, the buffer layer is etched to expose the surface of the substrate, and a third epitaxial layer is grown on the substrate at a third position, wherein the third position is adjacent to the second position; The first protective layer and the second protective layer are removed to obtain an RGB three-primary color Micro LED epitaxial wafer.

2. The method for preparing an RGB three-primary color Micro LED epitaxial wafer according to claim 1, characterized in that: The first epitaxial layer, the second epitaxial layer and the third epitaxial layer are a blue epitaxial layer, a green epitaxial layer and a red epitaxial layer respectively.

3. The method for preparing an RGB three-primary color Micro LED epitaxial wafer according to claim 1, characterized in that: The step of depositing a first protective layer on the surface of the first epitaxial layer comprises: Depositing a first protective material on the surface of the buffer layer, so that the first protective material wraps the first epitaxial layer at the first position, and covers the buffer layer at the second position and the third position; Photolithography and wet etching are used to remove the first protective material on the surface of the buffer layer at the second position and the third position to obtain a plurality of first protective layers respectively covering the surface of the first epitaxial layer in each light-emitting unit.

4. The method for preparing an RGB three-primary color Micro LED epitaxial wafer according to claim 1, characterized in that: The step of depositing a second protective layer on the surfaces of the first protective layer and the second epitaxial layer comprises: Depositing a second protective material on the surface of the buffer layer, so that the second protective material includes a first protective layer located at a first position, a second epitaxial layer located at a second position, and covers the buffer layer located at a third position; The second protective material on the surface of the buffer layer at the third position is removed by photolithography and wet etching to obtain a plurality of second protective layers respectively covering the surfaces of the first protective layer and the second epitaxial layer in each light-emitting unit.

5. The method for preparing an RGB three-primary color Micro LED epitaxial wafer according to claim 1, characterized in that: The first epitaxial layer and the second epitaxial layer have the same thickness.

6. The method for preparing an RGB three-primary color Micro LED epitaxial wafer according to claim 5, characterized in that: The thickness of the third epitaxial layer is equal to the sum of the thicknesses of the first epitaxial layer, the second epitaxial layer and the buffer layer.

7. The method for preparing an RGB three-primary color Micro LED epitaxial wafer according to claim 1, characterized in that: The substrate is made of GaAs material and has a thickness of 300 μm-600 μm; The buffer layer is made of AlN material and has a thickness of 100Å-5000Å.

8. The method for preparing an RGB three-primary color Micro LED epitaxial wafer according to claim 1, characterized in that: The first protective material used to make the first protective layer and the second protective material used to make the second protective layer are both SiO2, SiN X , TiO2, Al2O3, AlN materials.

9. An RGB three-primary color Micro LED epitaxial wafer, characterized in that: Prepared by the preparation method according to any one of claims 1 to 8, the epitaxial wafer comprises: substrate; a buffer layer disposed on the substrate and exposing a surface of the substrate at a third position; a first epitaxial layer, located on the buffer layer at a first position in each light-emitting unit; a second epitaxial layer, located on the buffer layer at the second position in each light-emitting unit; a third epitaxial layer located on the substrate at a third position in each light emitting unit; Wherein, in each light-emitting unit, the first position, the second position and the third position are arranged linearly, and the first epitaxial layer, the second epitaxial layer and the third epitaxial layer are arranged linearly.

10. The RGB three-primary color Micro LED epitaxial wafer according to claim 9, characterized in that: The first epitaxial layer, the second epitaxial layer and the third epitaxial layer are a blue epitaxial layer, a green epitaxial layer and a red epitaxial layer respectively.

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