阅读说明：本技术 一种衬底表面的微处理方法、复合衬底及led外延片 (Substrate surface micro-processing method, composite substrate and LED epitaxial wafer ) 是由 曾广艺 于 2021-07-23 设计创作，主要内容包括：本发明实施例公开了一种衬底表面的微处理方法、复合衬底及LED外延片,微处理方法包括：通过提供衬底,在衬底的一侧表面沉积非晶膜层,在非晶膜层远离衬底的一侧制备掩膜图形层,将制备完掩膜图形层的衬底进行时效处理,以使掩膜图形层向非晶膜层扩散,在非晶膜层的与掩膜图形层接触的界面形成扩散层,进一步图形化时效处理后的衬底,形成多个图形结构,由于扩散层与非晶膜层的致密度不同,当刻蚀时图形结构的表面形成有多个微结构凸起。本发明实施例提供的微处理方法可以对图形化衬底的图形结构表面进行粗化调控而不影响其它位置表面,增加图形结构的表面面积,提高图形化衬底的光反射效率,进而能够增加LED外延片外量子效率。(The embodiment of the invention discloses a micro-processing method for a substrate surface, a composite substrate and an LED epitaxial wafer, wherein the micro-processing method comprises the following steps: the substrate after aging treatment is further patterned to form a plurality of pattern structures, and because the diffusion layer and the amorphous film layer have different densities, a plurality of microstructure bulges are formed on the surface of each pattern structure during etching. The micro-processing method provided by the embodiment of the invention can coarsen and regulate the surface of the graphic structure of the graphical substrate without influencing the surfaces of other positions, increase the surface area of the graphic structure, improve the light reflection efficiency of the graphical substrate and further increase the external quantum efficiency of the LED epitaxial wafer.)

1. A method of micro-processing a surface of a substrate, comprising:

providing a substrate;

depositing an amorphous film layer on the surface of one side of the substrate;

preparing a mask pattern layer on one side of the amorphous film layer far away from the substrate;

performing aging treatment on the substrate on which the mask pattern layer is prepared so as to enable the mask pattern layer to diffuse towards the amorphous film layer and form a diffusion layer on an interface of the amorphous film layer, which is in contact with the mask pattern layer; wherein the diffusion layer and the amorphous film layer have different densities;

and patterning the substrate subjected to the aging treatment by using the mask pattern layer as a mask to form a plurality of pattern structures, wherein a plurality of microstructure bulges are formed on the surface of each pattern structure.

2. The micro-processing method according to claim 1, further comprising, after preparing a mask pattern layer on a side of the amorphous film layer away from the substrate:

and baking the mask pattern layer to adjust the solvent content ratio of the mask pattern layer.

3. A microprocessing method according to claim 2, wherein said mask pattern layer comprises a photoresist; the solvent content of the photoresist is 10-20%.

4. The micro-processing method according to claim 1, wherein the aging treatment of the substrate on which the mask pattern layer is prepared comprises:

and placing the substrate with the prepared mask pattern layer in a clean room environment, and standing under a shading condition.

5. The method of claim 1, wherein patterning the aged substrate to form a plurality of patterned structures having a plurality of microstructure protrusions formed on a surface thereof comprises:

etching the aged substrate by a dry etching process or a wet etching process, obtaining a required pattern structure on the amorphous film layer by adjusting the position covered by the mask pattern, and forming a plurality of microstructure bulges on the diffusion layer;

wherein the etching rate of the diffusion layer is less than that of the amorphous film layer.

6. The micro-processing method of claim 1, wherein the amorphous film layer comprises SIO₂And SiN_xAt least one of the materials.

7. A micro-processing method according to claim 1, wherein the pattern structures are arranged in an array;

the pattern structure comprises the amorphous film layer;

or, the pattern structure comprises the amorphous film layer and the substrate.

8. The microprocessing method according to claim 1, wherein the pattern structure comprises a polygonal pyramid, a cone, an elliptical pyramid, a cylinder, a circular truncated cone, or a spherical cap; the side wall of the graph structure is provided with a radian;

the microstructure protrusion comprises at least one of a truncated cone shape, a conical shape, a pyramid shape, a truncated pyramid shape and a spherical cap shape.

9. A composite substrate prepared by the method of micro-treating a surface of a substrate according to any one of claims 1 to 8; the composite substrate includes:

a substrate;

and the pattern structure is positioned on the substrate, and a plurality of microstructure bulges are formed on the surface of the pattern structure.

10. An LED epitaxial wafer comprising the composite substrate of claim 11, further comprising an epitaxial layer on the composite substrate.

Technical Field

The embodiment of the invention relates to the technical field of surface treatment, in particular to a micro-treatment method for a substrate surface, a composite substrate and an LED epitaxial wafer.

Background

The patterned substrate is the most main substrate material currently used for epitaxial growth of the gallium nitride LED, and the microstructure and optical parameters of the surface pattern of the patterned substrate have great influence on the quality of an epitaxial wafer, for example, the comprehensive quality of the epitaxy of the patterned substrate with the same size and different surface roughness has great difference after the same epitaxy process is carried out.

The size of a single pattern of the patterned substrate is generally in the micron order or below, and at present, few methods are available for performing coarsening control only on the surface of the pattern without affecting the surfaces of other positions.

Disclosure of Invention

The embodiment of the invention provides a micro-processing method for a substrate surface, a composite substrate and an LED epitaxial wafer, which can etch a surface with microstructure protrusions on a sapphire substrate and further achieve the effect of roughening a specific fine surface.

In a first aspect, an embodiment of the present invention provides a method for micro-processing a substrate surface, including:

providing a substrate;

depositing an amorphous film layer on the surface of one side of the substrate;

preparing a mask pattern layer on one side of the amorphous film layer far away from the substrate;

performing aging treatment on the substrate on which the mask pattern layer is prepared so as to enable the mask pattern layer to diffuse towards the amorphous film layer and form a diffusion layer on an interface of the amorphous film layer, which is in contact with the mask pattern layer; wherein the diffusion layer and the amorphous film layer have different densities;

and patterning the substrate subjected to the aging treatment by using the mask pattern layer as a mask to form a plurality of pattern structures, wherein a plurality of microstructure bulges are formed on the surface of each pattern structure.

Optionally, after preparing the mask pattern layer on the side of the amorphous film layer away from the substrate, the method further includes:

and baking the mask pattern layer to adjust the solvent content ratio of the mask pattern layer.

Optionally, the mask pattern layer includes photoresist; the solvent content of the photoresist is 10-20%.

Optionally, performing an aging treatment on the substrate on which the mask pattern layer is prepared, including:

and placing the substrate with the prepared mask pattern layer in a clean room environment, and standing under a shading condition.

Optionally, patterning the aged substrate to form a plurality of pattern structures, where a plurality of microstructure protrusions are formed on a surface of each pattern structure, and the patterning includes:

etching the aged substrate by a dry etching process or a wet etching process, obtaining a required pattern structure on the amorphous film layer by adjusting the position covered by the mask pattern, and forming a plurality of microstructure bulges on the diffusion layer;

wherein the etching rate of the diffusion layer is less than that of the amorphous film layer.

Optionally, the amorphous film layer includes at least one of SIO2 and SiNx material.

Optionally, the pattern structures form an array arrangement;

the pattern structure comprises the amorphous film layer;

or, the pattern structure comprises the amorphous film layer and the substrate.

Optionally, the graphic structure includes a polygonal pyramid, a cone, an elliptical pyramid, a cylinder, a circular truncated cone or a spherical crown; the side wall of the graph structure is provided with a radian;

the microstructure protrusion comprises at least one of a truncated cone shape, a conical shape, a pyramid shape, a truncated pyramid shape and a spherical cap shape.

In a second aspect, an embodiment of the present invention provides a composite substrate, which is prepared by using the method for micro-processing a substrate surface provided in the first aspect, and the composite substrate includes:

a substrate;

and the pattern structure is positioned on the substrate, and a plurality of microstructure bulges are formed on the surface of the pattern structure.

In a third aspect, an embodiment of the present invention provides an LED epitaxial wafer, including the composite substrate provided in the second aspect, and further including an epitaxial layer on the composite substrate.

The substrate surface micro-processing method provided by the embodiment of the invention comprises the steps of providing a substrate, depositing an amorphous film layer on the surface of one side of the substrate, preparing a mask pattern layer on the side, far away from the substrate, of the amorphous film layer, carrying out aging treatment on the substrate with the prepared mask pattern layer to enable the mask pattern layer to diffuse towards the amorphous film layer, forming a diffusion layer on an interface, in contact with the mask pattern layer, of the amorphous film layer, further patterning the substrate after the aging treatment to form a plurality of pattern structures, and forming a plurality of micro-structure bulges on the surface of each pattern structure during etching due to the fact that the diffusion layer and the amorphous film layer are different in density. The micro-processing method provided by the embodiment of the invention can coarsen and regulate the surface of the graphic structure of the graphical substrate without influencing the surfaces of other positions, increase the surface area of the graphic structure, improve the light reflection efficiency of the graphical substrate and further increase the external quantum efficiency of the LED epitaxial wafer.

Drawings

FIG. 1 is a flow chart of a method for micro-processing a surface of a substrate according to an embodiment of the present invention;

FIGS. 2-8 are schematic views of a fabrication process flow corresponding to the micro-processing method provided in FIG. 1;

FIG. 9 is an enlarged schematic view of one of the graphical structures provided in FIG. 7;

fig. 10 is a schematic structural diagram of an LED epitaxial wafer according to an embodiment of the present invention;

FIG. 11 is an electron microscope image of an etched surface of an amorphous film layer forming a diffusion layer according to an embodiment of the present invention;

FIG. 12 is an electron microscope image of an etched surface of an amorphous film without a diffusion layer provided in an embodiment of the invention;

FIG. 13 is a surface atomic force microscope image of a graphical structure provided by an embodiment of the present invention;

FIG. 14 is a surface electron microscope image of a patterned structure provided in accordance with an embodiment of the present invention;

FIG. 15 is a surface electron micrograph of a plurality of patterned structures provided by an embodiment of the present invention.

Detailed Description

The present invention will be described in further detail with reference to the accompanying drawings and examples. It is to be understood that the specific embodiments described herein are merely illustrative of the invention and are not limiting of the invention. It should be further noted that, for the convenience of description, only some of the structures related to the present invention are shown in the drawings, not all of the structures.

Fig. 1 is a flowchart of a method for micro-processing a substrate surface according to an embodiment of the present invention, which is applicable to the preparation of a sapphire substrate surface microstructure, and further, the prepared sapphire substrate may be used for preparing an LED epitaxial wafer. As shown in fig. 1, the micro-processing method includes:

s101, providing a substrate.

As shown in fig. 2, the substrate 101 may be a planar single crystal substrate, and the substrate 101 may be made of sapphire, silicon carbide, silicon nitride, zinc oxide, spinel, aluminum, copper, iron, silver, tungsten, nickel, or aluminum, for example, a conventional sapphire substrate.

S102, depositing an amorphous film layer on the surface of one side of the substrate.

As shown in fig. 3, an amorphous film layer 102 with adjustable density can be deposited on one side surface of a substrate 101 by a thin film preparation technique. The atoms of the amorphous film layer 102 are in a random arrangement state from the physical structure, have structural characteristics similar to those of a liquid state, have adjustable density, and the density of the contact surface of the amorphous film layer 102 is easy to change after the amorphous film layer is contacted with a mask material which is easy to diffuse.

S103, preparing a mask pattern layer on the side, far away from the substrate, of the amorphous film layer.

As shown in fig. 4, a mask pattern layer 103 is deposited on the amorphous film layer 102 on the side away from the substrate 101, the mask pattern 103 includes a solvent, a photosensitive resin, etc., and the desired mask pattern layer 103 is produced by a mask preparation technique, as shown in fig. 5. For example, the mask pattern layer 103 may be etched using a photolithography etching process into a matrix pattern structure as shown in fig. 5.

And S104, performing aging treatment on the substrate with the prepared mask pattern layer to diffuse the mask pattern layer to the amorphous film layer, and forming a diffusion layer on the interface of the amorphous film layer, which is in contact with the mask pattern layer.

Wherein, the density of the diffusion layer and the amorphous film layer is different.

Illustratively, as shown in fig. 5 and 6, the substrate 101 with the mask pattern layer 103 is subjected to an aging treatment, which is a heat treatment process in which a metal or alloy workpiece (e.g., mild steel or the like) is subjected to a solution treatment, quenched from a high temperature or deformed by a certain degree of cold working, and then left at a higher temperature or room temperature to maintain its shape and size, and the properties of which change with time. Generally, the hardness and strength increase and the plastic toughness and internal stresses decrease over time. In this embodiment, for example, the aging treatment may be performed by placing at room temperature, during the aging treatment, a certain amount of the material of the mask pattern layer 103 fills gaps and holes in the shallow surface layer of the amorphous film layer 102 through diffusion and permeation, for example, atoms or particles in the material of the mask pattern layer 103 cause a change in the etching resistance of a specific region on the surface of the amorphous film layer 102, and a diffusion layer 104 is formed at the interface of the amorphous film layer 102, which is in contact with the mask pattern layer 103, as shown in fig. 6. Due to the diffusion and permeation of the material of the mask pattern layer 103, the density of the diffusion layer 104 is different from that of the amorphous film layer 102, specifically, the density of the diffusion layer is greater than that of the amorphous film layer 102 without diffusion and permeation, and the higher the density, the stronger the etching resistance. Referring to fig. 6, by adjusting the material of the mask pattern layer 103 and the aging condition, the thickness of the diffusion layer is optionally 0-10% relative to the thickness of the amorphous film layer before aging in the direction perpendicular to the substrate 101.

And S105, with the mask pattern layer as a mask, patterning the substrate subjected to the aging treatment to form a plurality of pattern structures, wherein a plurality of microstructure bulges are formed on the surfaces of the pattern structures.

The aged substrate 101 may be patterned by etching or the like to form a plurality of pattern structures 105, using the mask pattern layer 103 in fig. 6 as a mask for photolithography, as shown in fig. 7, for example, fig. 9 is an enlarged schematic view of the triangular pattern structure 105 shown in fig. 7. Since the density of the diffusion layer 104 is higher than that of the amorphous film layer 102 without diffusion and penetration, when the patterning process is performed, the etching resistance of the region where the diffusion layer 104 has penetrating atoms or particles is stronger, and the region is not easily etched by the patterning process, so that a plurality of microstructure protrusions 106, such as conical protrusions, are formed on the triangular surface of the pattern structure 105, as shown in fig. 9. Since the microstructure protrusions 106 are present on the surface of the pattern structure 105, the effect of roughening the surface of the pattern structure 105 is achieved, so that the overall surface area of the pattern structure 105 is increased without changing the height and volume of the pattern structure 105. When the substrate 101 obtained by the micro-processing method is used for further preparing the LED epitaxial wafer, the substrate 101 with the coarsening design can improve the light reflection efficiency of the LED epitaxial wafer, and further improve the external quantum efficiency of the LED epitaxial wafer. The External Quantum Efficiency (EQE) is one of the main performance indexes of a photodetector, when photons are incident on the surface of a photosensitive device, part of the photons excite a photosensitive material to generate electron-hole pairs to form current, the ratio of collected electrons (subjected to processes such as internal electron-hole recombination) to the number of all incident photons is called the External Quantum Efficiency (EQE), and for a light emitting diode, the External Quantum Efficiency is equal to the ratio of the number of photons emitted in a unit time and a plane to the number of electron-hole pairs injected in the unit time and the plane. The number and distribution of the microstructured projections 106 is not particularly limited herein.

To sum up, in the method for micro-processing a substrate surface according to the embodiment of the present invention, a substrate is provided, an amorphous film layer is deposited on a surface of one side of the substrate, a mask pattern layer is prepared on a side of the amorphous film layer away from the substrate, the substrate on which the mask pattern layer is prepared is subjected to an aging treatment to diffuse the mask pattern layer toward the amorphous film layer, a diffusion layer is formed on an interface of the amorphous film layer, which is in contact with the mask pattern layer, and the aging-treated substrate is further patterned to form a plurality of pattern structures. The micro-processing method provided by the embodiment of the invention can coarsen and regulate the surface of the graphic structure of the graphic substrate without influencing the surfaces of other positions, increase the whole surface area of the graphic structure, improve the light reflection efficiency of the graphic substrate and further increase the external quantum efficiency of the LED epitaxial wafer.

Optionally, the amorphous film layer comprises SIO₂And SiN_xAt least in the materialOne, but not limited to the above. More materials may be selected depending on the actual substrate preparation.

Optionally, after the step S103 of the above embodiment, preparing the mask pattern layer on the side of the amorphous film layer away from the substrate, the method may further include:

step 201, baking the mask pattern layer to adjust the solvent content ratio of the mask pattern layer.

For example, with continued reference to fig. 4, the substrate 101 with the mask pattern layer 103 prepared thereon may be placed in an oven or on a hot plate for baking, and the solvent content of the mask pattern layer may be evaporated by high temperature or thermal conduction to adjust the solvent content ratio of the mask pattern layer, so as to facilitate the subsequent diffusion permeation aging treatment. For example, the baking temperature is 90 ℃ and the baking time is 1 minute.

Optionally, the mask pattern layer comprises photoresist; the solvent content of the photoresist is 10-20%.

For example, in the actual patterning process, the mask pattern layer may include a photoresist, and the commercially available photoresist generally includes photosensitive resin, sensitizer, and solvent, and the solvent content ratio of the photoresist is selected to be 10% -20%. For example, the photoresist may be baked to adjust the solvent content ratio to meet the aging requirements of a particular region.

On the basis of the foregoing embodiment, optionally, in step S104 of the foregoing embodiment, performing an aging treatment on the substrate on which the mask pattern layer is prepared may include:

step 301, placing the substrate with the prepared mask pattern layer in a clean room environment, and standing under a shading condition.

For example, with reference to fig. 5 and 6, the substrate 101 with the mask pattern layer 103 prepared is placed in a clean room environment, and is allowed to stand under a light-shielding condition, and the aging treatment performed in this way can be performed in an environment as simple and stable as possible, so that atoms or particles in the mask pattern layer 103 can be uniformly diffused and penetrated on the surface of the amorphous film layer 102 with adjustable density, and the etching resistance of the specific region on the surface of the amorphous film layer 102 after the aging treatment can be uniformly improved.

On the basis of the embodiment, the aging treatment time is T, wherein T is more than or equal to 240h and less than or equal to 360 h.

For example, the aging treatment time can be adjusted according to the etching resistance of the specific region on the surface of the amorphous film layer after diffusion and permeation, and specifically, the etching time can satisfy that T is more than or equal to 240h and less than or equal to 360 h. Microstructure bulges with different densities and sizes can be obtained later according to different amorphous film layer characteristics and aging treatment time combinations.

Optionally, in step S105 of the above embodiment, patterning the aged substrate to form a plurality of pattern structures, where a plurality of microstructure protrusions are formed on a surface of the pattern structure, and the patterning may include:

step 401, etching the aged substrate by a dry etching process or a wet etching process, obtaining a required pattern structure on the amorphous film layer by adjusting the position covered by the mask pattern, and forming a plurality of microstructure protrusions on the diffusion layer.

Wherein, the etching rate of the diffusion layer is less than that of the amorphous film layer.

Illustratively, with continued reference to FIGS. 6 and 7, the amorphous thin film layer 10 may optionally be SIO2 or SiN_xThe material is etched on the aged substrate 101 by a dry or wet etching process. By adjusting the position covered by the mask pattern, a desired pattern structure 105 is obtained in the amorphous film layer 102, and since the etching resistance of the region where the diffusion layer 104 has penetrating atoms or particles is strong, the density of the diffusion layer 104 is strong compared with the etching resistance of other amorphous film layers 102. When dry or wet etching is adopted, the etching rate of the diffusion layer 104 is lower than that of the amorphous film layer 102 through the pattern transfer effect of the etching, the diffusion layer is etched, a pattern structure 105 is formed right below the original position of the diffusion layer, and the diffusion layer with the lower etching rate forms a plurality of microstructure protrusions 106, namely a plurality of microstructure protrusions 106 are formed on the upper end surface of the pattern structure 105.

For example, when etching the substrate of the amorphous film layer with the diffusion layer after the aging treatment shown in fig. 6 for 10s with 6:1BOE solution, the 6:1BOE solution means 49% HF aqueous solution: 40% aqueous NH4F solution ═ 1: 6 (volume ratio) are mixed. For example, fig. 11 is an electron microscope image of an etched surface of an amorphous film layer for forming a diffusion layer according to an embodiment of the present invention; FIG. 12 is an electron microscope image of an etched surface of an amorphous film without a diffusion layer according to an embodiment of the present invention. The wet etching shows that in the embodiment, the etching rate of the amorphous film layer without the diffusion layer in the BOE solution of 6:1 is 906nm/min, the etching rate of the amorphous film layer with the diffusion layer in the BOE solution of 6:1 is 549nm/min, and the density of the diffusion layer is higher, so that the etching rate of the amorphous film layer with the diffusion layer is lower, and the etching surface of the amorphous film layer is more corrosion-resistant; meanwhile, as shown by comparison between fig. 11 and fig. 12, the etched surface of the amorphous film layer without the diffusion layer is rougher than the etched surface of the amorphous film layer with the diffusion layer, and the etched surface of the amorphous film layer with the diffusion layer is more uniform and dense than the etched surface of the amorphous film layer without the diffusion layer. FIG. 13 is a surface atomic force microscope image of a graphical structure provided by an embodiment of the present invention; FIG. 14 is a surface electron microscope image of a patterned structure provided in accordance with an embodiment of the present invention; FIG. 15 is a surface electron micrograph of a plurality of patterned structures provided by an embodiment of the present invention. As shown in fig. 13-15, which show the topography of the pattern structure, as shown in fig. 13 and 14, the surface of the pattern structure shown in fig. 15 has a plurality of microstructure protrusions, and the surface of the pattern structure has microstructure protrusions with different sizes, so that the overall surface area of the pattern structure is increased.

Alternatively, as shown in conjunction with fig. 7 and 8, the pattern structures 105 are arranged in an array; the pattern structure 106 includes an amorphous film layer 102; alternatively, the pattern structure 105 includes the amorphous film layer 102 and the substrate 101.

Illustratively, as shown in fig. 7 and 8, the aged substrate 101 is etched by a dry or wet etching process, such that the pattern structures 105 are arranged in an array, and the light reflection efficiency of the substrate 102 can be uniform. Meanwhile, the amorphous film layer 102 may be etched to form a pattern structure 105, as shown in fig. 7; alternatively, the substrate 101 is etched to make the pattern structure 105 include the amorphous film layer 102 and the substrate 101, further increasing the overall surface of the pattern structure, as shown in fig. 8. It should be noted that the specific etching depth needs to be determined according to the material of the substrate 101 and the design of the LED epitaxial wafer that further needs to be prepared, and the embodiment is not limited in particular, and only provides two feasible preparation ways for increasing the overall surface area of the pattern structure.

Optionally, the graphic structure comprises a polygonal cone, a cone, an elliptical cone, a cylinder, a circular truncated cone or a spherical crown; the side wall of the pattern structure has radian; the microstructure protrusion includes at least one of a truncated cone shape, a pyramid shape, a truncated pyramid shape, and a spherical cap shape.

Illustratively, considering that the shape of the pattern structure directly affects the growth quality of the epitaxial layer of the LED, the shape of the pattern structure needs to be reasonably set to reduce the dislocation density during epitaxial growth, reduce the generation of defects, and ensure the epitaxial quality. Therefore, the pattern structure can be set to be a polygonal cone, a cone, an elliptical cone, a cylinder, a circular truncated cone or a spherical crown, the side wall of the pattern structure has radian, the microstructure protrusion is at least one of a circular truncated cone type, a conical type, a pyramid type, a truncated pyramid type and a spherical crown type, and all the structural shapes of the whole surface of the pattern structure can be increased.

Optionally, the width of the bottom surface of the pattern structure may be 0.1-5 μm, and the height may be 0.2-4 μm; the width of the base of the microstructure protrusion may be 0.012-0.03 μm and the height may be 0.01-0.05 μm. Through measurement, the width and the height of the bottom surface of the prepared graph structure and the bottom surface of the microstructure protrusion have certain sizes by adopting the preparation method provided by the invention, the microstructure protrusion can effectively increase the overall surface area of the graph structure, and further the external quantum efficiency of the LED epitaxial wafer is prepared by adopting the substrate.

The invention provides a substrate surface micro-processing method, which utilizes the diffusion and permeation action of a mask material on the surface of an amorphous film layer with adjustable density to cause the etching resistance of a specific area on the surface of the amorphous film layer to change through aging treatment, and can etch a surface with microstructure protrusions on a corresponding area of a patterned substrate through subsequent dry etching or wet etching, thereby achieving the effect of coarsening the specific fine surface and further improving the external quantum efficiency of an LED epitaxial wafer prepared from the substrate.

Based on the same inventive concept, the embodiment of the invention also provides a composite substrate which is prepared by adopting the micro-processing method for the substrate surface provided by the embodiment. With continued reference to fig. 7 or 8, the composite substrate 100 includes:

a substrate 101; a pattern structure 105 is located on the substrate, and a plurality of microstructure protrusions 106 are formed on the surface of the pattern structure 105.

Illustratively, according to the composite substrate 100 provided by the embodiment of the present invention, since the plurality of microstructure protrusions 106 are formed on the surface of the pattern structure 105, the overall surface area of the pattern structure 105 is increased, the effect of roughening the surface of the substrate 101 is achieved, the light reflection efficiency of the substrate is improved, and the external quantum efficiency of the prepared LED epitaxial wafer is further improved.

Based on the same inventive concept, the embodiment of the invention also provides an LED epitaxial wafer. Fig. 10 is a schematic structural diagram of an LED epitaxial wafer according to an embodiment of the present invention, and referring to fig. 10, the LED epitaxial wafer includes the composite substrate 100 provided in the above embodiment, and further includes an epitaxial layer 200 formed on the patterned composite substrate 100.

For forming epitaxial layers on pattern structures of different materials, different LED epitaxial wafer growth techniques are required, and for the composite substrate 100 provided in the embodiment of the present invention, the epitaxial layer 200 on the LED epitaxial wafer may be a GaN, AlGaN epitaxial layer, or the like. Since the LED epitaxial wafer uses the composite substrate 100 provided in the above embodiment, the same advantageous effects as those of the composite substrate 100 can be obtained.

As a possible implementation, a specific example is illustrated, and the micro-processing method for the substrate surface provided in the above example is used for preparation, as shown in fig. 2 to 9, and the specific preparation method is as follows:

step S01: a sapphire single crystal substrate is provided as shown in fig. 2.

Step S02: a silicon oxide thin film layer with the thickness of 2um to 5um is deposited on a sapphire single crystal substrate through a thin film preparation technology, wherein the refractive index of the silicon oxide thin film layer is about 1.46, the BOE (6:1) corrosion rate is 1400nm/min, and the surface roughness Ra is about 6.5nm, as shown in figure 3.

Step S03: a desired mask pattern layer was formed on the silicon oxide thin film layer by photolithography, and the solvent content ratio of the mask pattern layer was adjusted to approximately 16%, as shown in fig. 4.

Step S04: the sapphire single crystal substrate after the steps S02 and S03 was placed in a clean room environment, and light-shielded and subjected to aging treatment for 240h to 360h, as shown in fig. 5, to form a diffusion layer at the interface of the silicon oxide thin film layer in contact with the mask pattern layer, as shown in fig. 6.

Step S05: the sapphire single crystal substrate after the aging treatment is etched by a dry etching process or a wet etching process to obtain a required patterned substrate or a required composite substrate, and a surface with microstructure protrusions is etched on the surface of the corresponding pattern at a position covered by the mask pattern, as shown in fig. 7-9.

In summary, in the composite substrate prepared by the method for micro-processing the substrate surface provided by the embodiment of the invention, since the density of the diffusion layer is relatively higher than that of the silicon oxide film layer without permeating or diffusing particles, when the diffusion layer is etched, the region of the diffusion layer is etched slowly, and a circular bulge is easily formed on the surface of the triangular structure, so that the overall surface area of the triangular bulge structure is improved, and the light reflectivity of the sapphire single crystal substrate is improved), thereby effectively improving the external quantum efficiency of the LED epitaxial wafer.

It is to be noted that the foregoing is only illustrative of the preferred embodiments of the present invention and the technical principles employed. It will be understood by those skilled in the art that the present invention is not limited to the particular embodiments described herein, but is capable of various obvious changes, rearrangements and substitutions as will now become apparent to those skilled in the art without departing from the scope of the invention. Therefore, although the present invention has been described in greater detail by the above embodiments, the present invention is not limited to the above embodiments, and may include other equivalent embodiments without departing from the spirit of the present invention, and the scope of the present invention is determined by the scope of the appended claims.