Patterned substrate, method of manufacture and LED epitaxial wafer

Abstract

Embodiments of the present application disclose a patterned substrate, a preparation method and an LED epitaxial wafer. _ 23) crystal face; wherein, the substrate surface is formed with a plurality of convex microstructures, the convex microstructure comprises a plurality of side faces, and at least one side face of the convex microstructure is a (11 _ 23) crystal face. Since the growth speed of the epitaxial material on the (11 _ 23) crystal face is slow, through the technical scheme provided by the embodiments of the present application, the growth speed of the epitaxial material on the side face of the convex microstructure can be reduced, and the epitaxial material is prevented from forming more crystal particles on the side face of the convex microstructure, so that the defects and stress formed in the merging process of the grains grown on the c face and the grains grown on the side face are reduced, and then the growth quality of the epitaxial material is improved, and the internal quantum efficiency of the LED epitaxial wafer is improved.

Description

TECHNICAL FIELD

[0001] Embodiments of the present application relate to the technical field of semiconductor manufacturing, and particularly relate to a patterned substrate, a preparation method and an LED epitaxial wafer. BACKGROUND

[0002] In the manufacturing process of a semiconductor chip, an epitaxial layer is grown on a prepared substrate. Due to the lattice matching and thermal expansion coefficient matching between the substrate and the epitaxial material, the epitaxial material has a very high dislocation density and internal stress, thereby reducing the internal quantum efficiency.

[0003] In order to obtain an epitaxial layer with low dislocation density and high crystal quality, a patterned substrate technology has been developed in the prior art. However, the pattern design of the existing patterned substrate is mostly focused on increasing the contact area of the epitaxial layer and the substrate, increasing the contact area to improve the external quantum efficiency, or reducing the refractive index of the substrate to increase the total reflection angle, so as to improve the external quantum efficiency. The above-mentioned means has a relatively poor effect on reducing the dislocation density and internal stress, and large grains different from the c-plane growth direction will still grow on the side surface of the pattern of the patterned substrate, which will still produce dislocations and other defects and large internal stress when the grains merge. SUMMARY

[0004] Based on the defects of the prior art, embodiments of the present application provide a patterned substrate, a preparation method and an LED epitaxial wafer to reduce the defect density of the epitaxial layer grown on the patterned substrate, thereby improving the internal quantum efficiency of the LED epitaxial wafer.

[0005] In a first aspect, embodiments of the present application provide a patterned substrate, comprising:

[0006] a substrate; the substrate belongs to a hexagonal crystal system, and the hexagonal crystal system includes (11 _ 23) crystal planes;

[0007] a plurality of raised microstructures formed on the surface of the substrate, the raised microstructures include a plurality of side surfaces, and at least one side surface of the raised microstructures is the crystal plane.

[0008] In a second aspect, embodiments of the present application also provide a preparation method of a patterned substrate for forming the patterned substrate of the first aspect of the present application, the preparation method comprising:

[0009] providing a substrate; the substrate belongs to a hexagonal crystal system, and the hexagonal crystal system includes crystal planes;

[0010] forming a mask layer on the surface of the substrate;

[0011] performing a patterning process on the mask layer to form a mask pattern;

[0012] etching the substrate based on the mask pattern to form a plurality of protruding microstructures on the surface of the substrate; the protruding microstructure comprises a plurality of side surfaces, and at least one side surface of the protruding microstructure is the crystal surface.

[0013] In a third aspect, the embodiment of the present application further provides an LED epitaxial wafer, comprising the patterned substrate according to the first aspect of the present application, and an epitaxial layer formed on the patterned substrate.

[0014] The patterned substrate provided by the embodiment of the present application comprises: a substrate, the substrate belongs to a hexagonal crystal system, and the hexagonal crystal system comprises a crystal surface; wherein a plurality of protruding microstructures are formed on the surface of the substrate, the protruding microstructure comprises a plurality of side surfaces, and at least one side surface of the protruding microstructure is the crystal surface. Since the growth speed of the epitaxial material on the crystal surface is slow, by the technical solution provided by the embodiment of the present application, the growth speed of the epitaxial material on the side surface of the protruding microstructure can be reduced, and the epitaxial material is prevented from forming more crystal particles on the side surface of the protruding microstructure, so that the defects and stress formed in the merging process of the grains grown on the c surface and the grains grown on the side surface are reduced, and then the growth quality of the epitaxial material is improved, and the internal quantum efficiency of the LED epitaxial wafer is improved. BRIEF DESCRIPTION OF DRAWINGS

[0015] Figure 1 A structural schematic diagram of a patterned substrate provided by the embodiment of the present application is shown in the figure;

[0016] Figure 2 A top view of a protruding microstructure provided by the embodiment of the present application is shown in the figure;

[0017] Figure 3 A schematic diagram of a cubic sapphire crystal surface is shown in the figure;

[0018] Figure 4 A schematic diagram of a top view of a sapphire crystal surface is shown in the figure;

[0019] Figures 5-7 Structural schematic diagrams of three kinds of protruding microstructures provided by the embodiment of the present application are shown in the figures;

[0020] Figure 8 A schematic diagram of a crystal structure of sapphire is shown in the figure;

[0021] Figure 9 A flowchart of a preparation method of a patterned substrate provided by the embodiment of the present application is shown in the figure;

[0022] Figure 10 A schematic diagram of a preparation method of a patterned substrate provided by the embodiment of the present application is shown in the figure;

[0023] Figure 11 Another flow chart of a method for preparing a patterned substrate according to an embodiment of the present application is provided;

[0024] Figure 12 A structural schematic diagram of a wafer according to an embodiment of the present application is provided;

[0025] Figure 13 A structural schematic diagram of a mask according to an embodiment of the present application is provided;

[0026] Figure 14 Another structural schematic diagram of a patterned substrate according to an embodiment of the present application is provided. DETAILED DESCRIPTION

[0027] The present application will be further described below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are intended to be merely illustrative of the present application and not in limitation thereof. It should also be noted that, for the purpose of description, only the parts related to the present application are shown in the accompanying drawings rather than all the parts.

[0028] Currently, the substrate materials mainly include sapphire substrate, silicon substrate, aluminum nitride substrate, silicon carbide substrate and gallium nitride substrate, wherein the sapphire substrate, aluminum nitride substrate, silicon carbide substrate and gallium nitride substrate all belong to hexagonal system. The crystal structures of sapphire, aluminum nitride, silicon carbide and gallium nitride are all hexagonal wurtzite structure or similar hexagonal wurtzite structure. In the prior art, the patterned substrate prepared by the material with hexagonal wurtzite structure has a side surface of the pattern structure on the patterned substrate, which is the r surface of the material, i.e. The r surface and n surface are alternately surrounded by the m surface and a surface.

[0029] In the process of epitaxial material growth, the epitaxial material (such as gallium nitride) will nucleate and grow on the c surface of the patterned substrate and the side surface of the pattern structure, wherein the c surface of the patterned substrate is the exposed part of the surface on the side of the patterned substrate with the pattern structure. The inventors have found that, when the epitaxial material is deposited on the side surface of the pattern structure, the epitaxial material will have different growth rates on the side surface of the pattern structure due to the different crystal surfaces of the different substrate materials included in the side surface of the pattern structure. When the crystal grains grown on the c surface merge with the large particles formed on the side surface, the grain boundaries will be formed, thereby forming defects such as linear dislocations and planar dislocations, and internal stress will also be generated due to the difference in growth, which will result in low quality of the epitaxial layer and large internal stress in the epitaxial layer.

[0030] Therefore, the inventors propose the technical solutions in the present application. Specifically, the present application provides a patterned substrate, which comprises:

[0031] ​A substrate;

[0032] The substrate belongs to a hexagonal crystal system, and the hexagonal crystal system includes A crystal face;

[0033] The substrate surface is formed with a plurality of raised microstructures, and the raised microstructure includes a plurality of side faces, at least one side face of the raised microstructure is A crystal face.

[0034] Through the above technical solution, since the growth rate of the epitaxial material on the Crystal face is slow, the growth rate of the epitaxial material on the side face of the raised microstructure can be reduced, and the epitaxial material is prevented from forming more crystal particles on the raised microstructure, thereby reducing defects and stress formed in the merging process of the grains grown on the c face and the grains grown on the side face, and further improving the growth quality of the epitaxial material and the internal quantum efficiency of the LED epitaxial wafer.

[0035] The above is the core idea of the present application, and the technical solutions in the embodiments of the present application will be described clearly and completely in combination with the drawings in the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0036] Figure 1 A structural schematic diagram of a patterned substrate provided by the embodiment of the present application is shown in Figure 2 A top view of a raised microstructure provided by the embodiment of the present application is shown in Figure 1 and Figure 2 As shown in the drawings, the patterned substrate includes a substrate 1, the substrate 1 belongs to a hexagonal crystal system, and the hexagonal crystal system includes A crystal face; a plurality of raised microstructures 2 are formed on the surface of the substrate 1, the raised microstructure 2 includes a plurality of side faces 3, and at least one side face 3 of the raised microstructure 2 is A crystal face.

[0037] Specifically, as shown in Figure 1 and Figure 2 , the patterned substrate includes a substrate 1, wherein the substrate 1 belongs to a hexagonal crystal system, that is, the material forming the substrate 1 is a hexagonal crystal. The substrate can be any one of the above-mentioned sapphire substrate, aluminum nitride substrate, silicon carbide substrate or gallium nitride substrate, and the embodiment of the present application is introduced with the substrate 1 being a sapphire substrate, and the actual substrate 1 material is not limited thereto.

[0038] According to the above content, it can be known that in the prior art, when a hexagonal crystal system is used as a substrate material, the side face of the pattern structure of the patterned substrate is formed by the r face, that is A crystal face, and the n face, that is The plurality of crystal faces consists of a plurality of crystal faces including a crystal face. For the convenience of description, the following refers to the r face as the hexagonal crystal The crystal face, the n face refers to the hexagonal crystal The crystal face.

[0039] With reference to the foregoing Figure 1 And Figure 2 In the embodiment of the present application, the surface of the substrate 1 is formed with a plurality of protruding microstructures 2, which can be obtained by etching the surface of the substrate. That is to say, the protruding microstructure 2 is an integral structure with the substrate 1. The protruding microstructure 2 includes a plurality of side faces 3, wherein at least one side face 3 of the protruding microstructure 2 is an n face of the material of the substrate 1. Figure 3 A schematic view of a stereoscopic sapphire crystal face is shown in FIG. Figure 4 A schematic view of a planar sapphire crystal face is shown in FIG. Figure 3 In the embodiment of the present application, at least one side face 3 of the protruding microstructure 2 is controlled to be an n face. Figure 2 In the embodiment of the present application, all side faces 3 of the protruding microstructure 2 are n faces, but the actual setting mode is not limited thereto. Those skilled in the art can understand that Figure 2 And Figure 3 In the embodiment of the present application (0001) and The crystal face index of the sapphire material, specifically, The crystal face index of the n face is represented by n; The crystal face index of the r face is represented by r; and

[0040] According to research, the proportion of Al-hanging bonds of the r face can reach about 50%, while the proportion of Al-hanging bonds of the n face is only about 18.75%. The existence of Al-hanging bonds is beneficial to the nucleation and growth of epitaxial material, so the growth speed of epitaxial material on the r face is faster and large-grain epitaxial grains are formed in the time when the epitaxial material covers the side face of the protruding microstructure; while the nucleation condition of epitaxial material on the n face is less, the growth speed of epitaxial material is slower and it is not easy to form large-grain epitaxial grains in the time when the epitaxial material covers the side face of the protruding microstructure.

[0041] Therefore, in the embodiment of the present application, at least one side face of each protruding microstructure of the patterned substrate is set to be an n face of the substrate material, thereby reducing the growth speed of epitaxial material on the side face of the protruding microstructure, avoiding the formation of more crystal grains of epitaxial material on the side face of the protruding microstructure, reducing the defects and stress formed in the merging process of the grains grown on the c face and the grains grown on the side face, and further improving the growth quality of epitaxial material and the internal quantum efficiency of the LED epitaxial wafer.

[0042] The patterning substrate can be prepared by the following process: first, providing a substrate belonging to a hexagonal crystal system, such as a sapphire substrate, the sapphire substrate including an n surface; then forming a mask layer on the surface of the substrate, and then patterning the mask layer to form a mask pattern on the surface of the substrate; and then etching the substrate based on the mask pattern to form a plurality of protruding microstructures on the surface of the substrate.

[0043] The specific implementation of the preparation process can be set by those skilled in the art according to actual conditions, and the embodiments of the present application do not limit this.

[0044] For example, the sapphire substrate can be a sapphire flat plate substrate, the mask layer can be a photoresist layer, and the photoresist can be uniformly coated on the surface of the sapphire substrate by uniform coating. Further, the mask layer can be patterned by a photolithography exposure process to form a mask pattern on the surface of the substrate, and the mask pattern is a plurality of photoresist columns.

[0045] Further, the surface of the substrate with the mask pattern is etched by an etching process to form protruding microstructures on the surface of the substrate. It should be noted that the side surface of the protruding microstructure formed by the etching process should be the n surface of the substrate material.

[0046] It should be noted that the specific implementation of the etching process is not limited by the embodiments of the present application, and those skilled in the art can select according to actual needs. Any method of processing the substrate by an etching process to prepare a protruding microstructure with an n surface on the surface of the substrate is within the scope of the technical solutions protected by the embodiments of the present application. For example, the substrate can be processed by dry etching and / or wet etching, but is not limited thereto.

[0047] The patterning substrate provided by the embodiments of the present application includes: a substrate, the substrate belongs to a hexagonal crystal system, the hexagonal crystal system includes a crystal surface; wherein a plurality of protruding microstructures are formed on the surface of the substrate, the protruding microstructure includes a plurality of side surfaces, and at least one side surface of the protruding microstructure is a crystal surface. In this way, the growth rate of the epitaxial material on the side surface of the protruding microstructure is reduced, and the formation of a large number of crystal particles of the epitaxial material on the side surface of the protruding microstructure is avoided, the defects and stresses formed in the merging process of the grains grown on the c surface and the grains grown on the side surface are reduced, and the growth quality of the epitaxial material is improved, and the internal quantum efficiency of the LED epitaxial wafer is improved.

[0048] Optionally, in some preferred embodiments, all side surfaces of the protruding microstructure can be n surfaces, further improving the quality of the epitaxial layer grown on the patterning substrate. Figures 5-7 The structure of the three protruding microstructures provided by the embodiments of the present application is shown in the structure diagram. Figures 5-7In this embodiment of the invention, the protruding microstructure 2 includes at least a triangular pyramidal protruding microstructure, a regular hexagonal pyramidal protruding microstructure, or a hexagonal star pyramidal protruding microstructure.

[0049] Specifically, the inventors discovered that there are 6 n-faces converging at the same point based on the c-face. By arranging and combining these faces and removing duplicates, the remaining graphic structures include at least 4 types. If all sides of the raised microstructure are n-faces, then the raised microstructure includes at least a triangular pyramid raised microstructure, a regular hexagonal pyramid raised microstructure, or a hexagonal star pyramid raised microstructure. Figure 2 and Figure 5 The structures shown are all triangular pyramidal protrusions 2. Figure 2 It is a regular triangular pyramidal protruding microstructure; Figure 6 It has a regular hexagonal pyramidal protruding microstructure. Figure 6 Figure (a) is a schematic diagram of the three-dimensional structure, and Figure (b) is a top view; Figure 7 It has a hexagonal pyramidal protrusion microstructure. Figure 7 Figure (a) is a schematic diagram of the three-dimensional structure, and Figure (b) is a top view.

[0050] It is understandable that when forming the aforementioned protruding microstructure, the bottom surface pattern of the protruding microstructure will also be different depending on the specific shape of the protruding microstructure. The bottom surface pattern of the protruding microstructure is the pattern formed by the sides of the protruding microstructure that connect with the substrate surface. For example, when the protruding microstructure is a regular triangular pyramid, the bottom surface pattern should be an equilateral triangle; when the protruding microstructure is a regular hexagonal pyramid, the bottom surface pattern should be a regular hexagon. Therefore, in this embodiment of the invention, the bottom surface pattern of the protruding microstructure can be designed to obtain a protruding microstructure with n sides.

[0051] For example, Figure 8 This is a schematic diagram of the crystal structure of sapphire, for reference. Figure 2 and Figure 8 In one possible embodiment, the extension direction of any edge of the bottom surface pattern of the protruding microstructure 2 is parallel to that of the substrate 1. The included angle θ1 between crystal orientations is 30°.

[0052] Specifically, refer to Figure 8 Sapphire includes Crystal orientation, The crystal orientation is parallel to the c-plane of the sapphire, that is... The crystal orientation is parallel to the substrate surface. The inventors discovered that, in order to make the side surface 3 of the protruding microstructure 2 the n-plane of the substrate 1, the extension direction of any edge of the bottom surface pattern of the protruding microstructure 2 can be controlled to be parallel to the substrate 1. The crystal orientations are at a 30° angle to each other. Figure 2 The middle view is a top view of the protruding microstructure 2. Figure 2The external profile shape of the pattern shown in the figure is the bottom surface pattern of the convex microstructure 2.

[0053] When the convex microstructure 2 is any one or more of the above, Figure 2 , Figures 5-8 , if the specific pattern shape of the convex microstructure 2 is determined, and the extension direction of any one side of the bottom surface pattern of the convex microstructure 2 forms an angle of 30° with the crystal direction of the substrate 1, the angles of the sides of the bottom surface pattern of the convex microstructure 2 can also be determined accordingly, and the convex microstructure 2 obtained in this arrangement is a convex microstructure 2 with all sides being n faces.

[0054] Optionally, in a possible embodiment, the angle between the normal of at least one side of the convex microstructure and the normal of the substrate surface is 61.75°.

[0055] Specifically, as shown by the sapphire crystal surface, Figure 4 , the positional relationship between each crystal face of the substrate and the substrate surface, i.e., the c face of the sapphire, is different, so the angle between the normal of each crystal face and the normal of the c face is different. The normal of each crystal face can also be understood as the extension direction of the crystal face index of each crystal face. According to crystallographic knowledge, the angle θ2 between the normal of the n face of the substrate and the normal of the c face should be 61.75°. Therefore, in the embodiments of the present application, the angle between the normal of at least one side of the convex microstructure and the normal of the substrate surface can be set to 61.75° to realize that at least one side of the convex microstructure is an n face of the substrate. If all the sides of the convex microstructure are composed of n faces, the angle between the normal of each side and the normal of the c face of the substrate surface can be set to 61.75°.

[0056] Optionally, the hexagonal system also includes a (0001) crystal face, and the substrate surface between adjacent convex microstructures 2 is a (0001) crystal face. The (0001) crystal face is also the c face of the sapphire substrate, i.e., the part of the patterned substrate surface on which the convex microstructure 2 is not arranged, and the subsequent epitaxial material will be epitaxially grown on the (0001) crystal face.

[0057] Optionally, in a possible embodiment, the minimum distance d between adjacent convex microstructures 2 on the surface of the substrate 1 is less than or equal to 0.2 μm.

[0058] Specifically, in the embodiments of the present application, the minimum distance d between adjacent convex microstructures 2 on the patterned substrate surface can be set to be less than or equal to 0.2 μm, thereby improving the pattern density of the convex microstructure 2 on the patterned substrate and further improving the growth effect of the epitaxial material.

[0059] Based on the same concept, the embodiments of the present application also provide a preparation method of a patterned substrate for forming the patterned substrate provided by any embodiment of the present application, Figure 9A flow chart of a method for preparing a patterned substrate is provided in the embodiments of the present application, Figure 10 A schematic diagram of a method for preparing a patterned substrate is provided in the embodiments of the present application, as shown in Figure 2 、 Figure 9 and Figure 10 , the method comprises:

[0060] S110, providing a substrate.

[0061] Referring to a) of FIG. Figure 10 , wherein the crystal structure of the substrate 1 belongs to hexagonal system, the hexagonal system includes crystal surface. The substrate 1 can be a sapphire substrate, which includes crystal surface, i.e. n surface.

[0062] S120, forming a mask layer on the surface of the substrate.

[0063] Referring to b) of FIG. Figure 10 , wherein the mask layer 4 can be a photoresist layer, which can be uniformly coated on the surface of the sapphire substrate by spin coating to form the mask layer 4.

[0064] S130, patterning the mask layer to form a mask pattern.

[0065] Referring to c) of FIG. Figure 10 , further, if the mask layer 4 is a photoresist layer, the pattern on the mask plate can be transferred to the surface of the substrate by photolithography exposure process to form a mask pattern 5 on the surface of the substrate, which is a plurality of photoresist columns.

[0066] S140, etching the substrate based on the mask pattern to form a plurality of protruding microstructures on the surface of the substrate.

[0067] Referring to d) of FIG. Figure 10 , further, the surface of the substrate 1 with the mask pattern 5 is etched by etching process to form a plurality of protruding microstructures 2 on the surface of the substrate. The protruding microstructure 2 includes a plurality of side surfaces 3, and at least one side surface 3 of the protruding microstructure 2 is crystal surface. That is, at least one side surface 3 of the protruding microstructure 2 formed by etching process should be n surface of the substrate material.

[0068] By setting at least one side surface of the protruding microstructure of the patterned substrate surface to be The crystal face can reduce the growth speed of the epitaxial material on the side of the convex microstructure, avoid the formation of more crystal particles on the side of the convex microstructure, reduce defects and stress formed in the merging process of the grains grown on the c face and the grains grown on the side face, and further improve the growth quality of the epitaxial material and the internal quantum efficiency of the LED epitaxial wafer.

[0069] Optionally, in some possible embodiments, the convex microstructure at least includes a triangular pyramid convex microstructure, a regular hexagonal pyramid convex microstructure, or a hexagonal star pyramid convex microstructure.

[0070] In the embodiment of the present application, the pattern on the mask plate can be designed before S130 to ensure that the pattern on the mask plate is the same as the bottom face pattern shape of the final convex microstructure.

[0071] In the embodiment of the present application, how to make at least one side of the convex microstructure an n face through the etching process is not limited, and a person skilled in the art can set it according to actual needs. For example, the process parameters of the mask layer patterning process (such as the shape of the pattern on the mask plate) or the etching parameters in the etching process can be adjusted, but are not limited thereto.

[0072] Optionally, in one possible embodiment, the above preparation method can be refined, and specifically, S110 can be refined. For example, the substrate is provided, which can include: providing a wafer, taking the wafer as the substrate, and the wafer having a flat edge; before the mask layer is patterned to form a mask pattern, further comprising: providing a mask plate, the mask plate being provided with a mask pattern corresponding to the bottom face pattern of the convex microstructure; placing the mask plate above the wafer and adjusting the mask plate so that the vertical projection of the mask pattern on the wafer surface satisfies that the extension direction of any one side of the mask pattern and the flat edge of the wafer form a 30° angle; wherein the extension direction of the flat edge and the The crystal direction is parallel to the wafer surface, and the angle between the extension direction of the flat edge and the The angle between the extension direction of the flat edge and the

[0073] Figure 11 A flowchart of another method for preparing a patterned substrate provided by the embodiment of the present application is shown in FIG. 6. Figure 12 A structure diagram of a wafer provided by the embodiment of the present application is shown in FIG. 7, which can be combined with reference to FIG. 6. Figure 11 and Figure 12 The preparation method comprises the following steps:

[0074] S210, providing a wafer, taking the wafer as the substrate, and the wafer having a flat edge.

[0075] Specifically, referring to Figure 12 , in the embodiment, the substrate can be a wafer 6, and the wafer 6 includes a flat edge 7. The crystal direction of the wafer 6 can be determined according to the direction of the straight line where the flat edge 7 is located. In the embodiment, the extension direction of the straight line where the flat edge 7 is located and the crystal direction of the wafer 6 form a 60° angle, and the crystal direction of the wafer 6 is the n direction of the substrate material. The crystal direction of the wafer 6 is the n direction of the substrate material. The crystal direction of the wafer 6 is the n direction of the substrate material. The crystal direction of the wafer 6 is the n direction of the substrate material.

[0076] S220, forming a mask layer on the surface of the substrate.

[0077] S230, providing a mask plate, and the mask plate is provided with a mask pattern corresponding to the bottom surface pattern of the convex microstructure.

[0078] Figure 13 A structural schematic diagram of a mask plate provided by an embodiment of the present application is shown in the figure, Figure 14 A structural schematic diagram of another patterned substrate provided by an embodiment of the present application is shown in the figure, Figure 13 , a mask plate 8 is provided, and the mask plate 8 is provided with a mask pattern 9 corresponding to the bottom surface pattern of the convex microstructure. For example, if the bottom surface pattern of the convex microstructure is a regular triangle, the mask pattern 9 on the mask plate is also a regular triangle; if the bottom surface pattern of the convex microstructure is a regular hexagon, the mask pattern 9 on the mask plate is also a regular hexagon; if the bottom surface pattern of the convex microstructure is a hexagonal star, the mask pattern 9 on the mask plate is also a hexagonal star.

[0079] S240, placing the mask plate above the wafer and adjusting the mask plate so that the vertical projection of the mask pattern on the surface of the wafer satisfies that the extension direction of any one side of the mask pattern and the flat edge of the wafer form a 30° angle.

[0080] Continuing to refer to Figure 13 and Figure 14 , the surface of the wafer 6 is the c face of sapphire, and the crystal direction of the wafer 6 is the n direction of sapphire. The crystal direction of the wafer 6 is the n direction of sapphire. The crystal direction of the wafer 6 is the n direction of sapphire. The extension direction of the flat edge 7 and the crystal direction of the wafer 6 are parallel to the c face of sapphire, and the extension direction of the flat edge 7 and the crystal direction of the wafer 6 form a 60° angle. Thus, the crystal direction of sapphire can be determined according to the extension direction of the flat edge 7 of the wafer 6. The crystal direction of the wafer 6 is the n direction of sapphire. The crystal direction of the wafer 6 is the n direction of sapphire.

[0081] Specifically, the mask plate 8 is placed above the wafer 6 to transfer the mask pattern 9 on the mask plate 8 to the surface of the wafer by a photolithography exposure process. As known from the above embodiment, in order to realize that the side surface of the convex microstructure is the n face of the substrate, the extension direction of any one side of the bottom surface pattern of the convex microstructure and the n face of the substrate can be controlled. The angle between the crystal directions is 30°. In this step, the extension direction of any one side of the mask 8 is set to be 30° with the flat side 7 of the wafer, so as to ensure that the extension direction of any one side of the bottom surface pattern of the final formed convex microstructure is 30° with the flat surface of the substrate. The angle between the crystal directions is 30°. Figure 14 The convex microstructure on the patterned substrate shown in the above embodiment is a regular hexagonal pyramid convex microstructure, as shown in the above embodiment. Figure 14 As shown in the above embodiment, in the regular hexagonal bottom surface pattern of the regular hexagonal pyramid convex microstructure, the sides other than the side vertical to the flat side 7 are all 30° with the flat side 7. Of course, in the actual preparation process, the arrangement mode of the convex microstructure is not limited to this, and those skilled in the art can set it according to the actual needs.

[0082] S250, performing a patterned treatment on the mask layer to form a mask pattern.

[0083] It can be understood that the mask pattern formed at this time, i.e., the bottom surface pattern of each photoresist column, is consistent with the bottom surface pattern shape of the final required convex microstructure, and the size is different, and the angle between the extension direction of any one side of the bottom surface pattern of the photoresist column and the flat side 7 of the wafer 6 is 30°.

[0084] S260, based on the mask pattern, etching the substrate to form a plurality of convex microstructures on the surface of the substrate.

[0085] The convex microstructure includes a plurality of side surfaces, and at least one side surface of the convex microstructure is A crystal surface.

[0086] The above steps are the same as those in the above embodiment, and will not be described here.

[0087] Optionally, in another possible embodiment of the present application, based on the mask pattern, etching the substrate to form a plurality of convex microstructures on the substrate, including: based on the mask pattern, using a dry etching and / or wet etching method to perform a patterned treatment on the substrate to form a plurality of convex microstructures on the surface of the substrate; the angle between the normal line of at least one side surface of the convex microstructure and the normal line of the surface of the substrate is 61.75°.

[0088] Specifically, in this embodiment, the substrate can be etched again based on the mask pattern by using a dry etching and / or wet etching method. The dry etching refers to the physical and / or chemical reaction of plasma on the surface of the substrate to remove the material on the surface of the substrate, and the wet etching refers to the chemical removal of the material on the surface of the substrate by using a chemical reagent.

[0089] The plurality of convex microstructures are formed on the substrate surface by dry etching and / or wet etching, and the process parameters of the dry etching and / or wet etching are adjusted so that the included angle between the normal of at least one side of the convex microstructure and the normal of the substrate surface is 61.75°.

[0090] Optionally, in one possible embodiment, the substrate is patterned based on the mask pattern by using dry etching and / or wet etching to form a plurality of convex microstructures on the substrate surface, including:

[0091] The substrate is patterned based on the mask pattern by using dry etching to form a plurality of basic convex microstructures on the substrate surface, and the at least one side of the basic convex microstructure is modified by using wet etching to form the convex microstructure.

[0092] Specifically, in the embodiment of the present application, the substrate surface is etched by using dry etching to form a plurality of basic convex microstructures on the substrate surface. The included angle between the normal of the side of the basic convex microstructure and the normal of the substrate surface is close to 61.75°, and then the at least one side of the basic convex microstructure is modified by using wet etching to obtain the convex microstructure. After the modification by wet etching, the included angle between the normal of the at least one side of the convex microstructure and the substrate surface is 61.75°. And after the wet etching, the convex microstructure can have more distinct edges.

[0093] In the embodiment of the present application, the specific etching process parameters of the dry etching and wet etching are not limited, and the process parameters can be adjusted by the person skilled in the art in the actual preparation process. In one exemplary embodiment, the conditions of the wet etching can be using a mixed solution of sulfuric acid:phosphoric acid=5:1 to etch at 260°C.

[0094] In the following, the dry etching and wet etching processes are introduced in one specific embodiment. In the embodiment, the patterned substrate can be referred to as shown in FIG. 1 of the accompanying drawings, and the bottom surface pattern of the regular hexagonal pyramid convex microstructure can be a regular hexagon with a side length of 1.4 μm. Figure 14

[0095] ​Specifically, first, a photoresist mask layer with a thickness of 2.6-2.7 μm is spin-coated on the surface of a sapphire substrate, the photoresist mask layer is exposed by using a mask plate, the pattern on the mask plate has an angle of 30° with the horizontal direction of the sapphire substrate, after exposure and development, the sapphire substrate is dry etched by using a conventional inductive coupled plasma (ICP) to transfer the pattern on the mask plate to the surface of the sapphire substrate, and a basic convex microstructure is formed; then, the height of the basic convex microstructure is controlled to be about 2.2 μm by controlling the process parameters and adjusting the selection ratio. Due to the characteristics of the photoresist, the basic convex microstructure after dry etching is close to the required side surface full n-face regular hexagonal pyramid convex microstructure, but the pattern corners are not obvious, therefore, after dry etching, the etched patterned substrate can be cleaned by using a mixed solution of sulfuric acid and hydrogen peroxide, and then the patterned substrate is placed in a mixed solution of sulfuric acid and phosphoric acid with a ratio of 5:1 for wet etching at a temperature of 260 °C, at this time, due to the difference in etching speed of different crystal faces, the regular hexagonal pyramid convex microstructure with side surface composed of n faces can be obtained after wet etching.

[0096] The embodiment of the present application also provides an LED epitaxial wafer, which comprises the patterned substrate provided by any of the embodiments of the present application and an epitaxial layer formed on the patterned substrate.

[0097] For the patterned substrate provided by the embodiment of the present application, the epitaxial layer on the corresponding LED epitaxial wafer can be GaN, AIGaN epitaxial layer, etc. The LED epitaxial wafer provided by the embodiment of the present application comprises all the technical features and corresponding beneficial effects of the patterned substrate provided by any of the embodiments of the present application, which will not be described here.

[0098] It should be noted that the above are only the preferred embodiments of the present application and the technical principles applied. Those skilled in the art will understand that the present application is not limited to the specific embodiments herein, and those skilled in the art can make various obvious changes, re-adjustments, mutual combinations and substitutions without departing from the protection scope of the present application. Therefore, although the present application has been described in more detail through the above embodiments, the present application is not limited to the above embodiments, and can include more other equivalent embodiments without departing from the concept of the present application, and the scope of the present application is determined by the scope of the appended claims.

Claims

1. A patterned substrate, characterized in that, The substrate surface is provided with a plurality of convex microstructures, the convex microstructures comprising a plurality of side surfaces. a substrate; the substrate belongs to a hexagonal crystal system, the hexagonal crystal system includes a crystal face; The hexagonal system further comprises a (0001) crystal face, and the substrate surface between adjacent convex microstructures is the (0001) crystal face. The convex microstructure and the substrate are an integral structure; the extension direction of any side of the bottom surface pattern of the convex microstructure is perpendicular to the The angle between the crystal directions is 30°, all the side surfaces of the convex microstructure are the The angle between the normal line of the side surface of the convex microstructure and the normal line of the substrate surface is 61.75°.

2. The patterned substrate of claim 1, wherein, The minimum distance between adjacent convex microstructures on the substrate surface is less than or equal to 0.2 μm.

3. The patterned substrate of claim 1, wherein, The convex microstructures comprise at least a triangular pyramid convex microstructure, a regular hexagonal pyramid convex microstructure, or a hexagonal star pyramid convex microstructure.

4. The patterned substrate of claim 1, wherein, A method for forming the patterned substrate of any one of claims 1-4, the method comprising:

5. A method of preparing a patterned substrate, characterized in that, forming a mask layer on the substrate surface; A substrate is provided; the substrate belongs to a hexagonal crystal, the hexagonal crystal includes A crystal face; performing a patterning process on the mask layer to form a mask pattern; performing etching on the substrate based on the mask pattern to form a plurality of convex microstructures on the substrate surface, the convex microstructures comprising a plurality of side surfaces; The substrate is provided by: The convex microstructure and the substrate are an integral structure; the extension direction of any one side of the bottom surface pattern of the convex microstructure is perpendicular to the The angle between the crystal directions is 30°, all the side surfaces of the convex microstructure are the Crystal faces, and the angle between the normal lines of all the side surfaces of the convex microstructure and the normal line of the substrate surface is 61.75°.

6. The production method according to claim 5, wherein providing a wafer as the substrate, the wafer having a flat edge; Before the step of performing a patterning process on the mask layer to form a mask pattern, the method further comprises: providing a mask plate, the mask plate being provided with a mask pattern corresponding to the bottom surface pattern of the convex microstructures; The step of performing etching on the substrate based on the mask pattern to form a plurality of convex microstructures on the substrate comprises: The mask is placed above the wafer, and the mask is adjusted so that the vertical projection of the mask pattern on the wafer surface satisfies that the extension direction of any one side of the mask pattern and the extension direction of the flat side of the wafer form a 30° angle; wherein the extension direction of the flat side and the crystal direction of the wafer are parallel to the wafer surface, and the angle between the extension direction of the flat side and the crystal direction of the wafer is 60°. are parallel to the wafer surface, and the angle between the extension direction of the flat side and the crystal direction of the wafer is 60°.

7. The preparation method according to claim 5, characterized in that, performing a patterning process on the substrate based on the mask pattern by using a dry etching method and / or a wet etching method to form a plurality of convex microstructures on the substrate surface. The step of performing a patterning process on the substrate based on the mask pattern by using a dry etching method and / or a wet etching method to form a plurality of convex microstructures on the substrate surface comprises:

8. The preparation method according to claim 7, characterized in that, performing a patterning process on the substrate based on the mask pattern by using a dry etching method to form a plurality of base convex microstructures on the substrate surface; performing a modification on the side surfaces of the base convex microstructures by using a wet etching method to form the convex microstructures. The method further comprises forming an epitaxial layer on the patterned substrate.

9. An LED epitaxial wafer, characterized by, ​

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