Patterned substrate with concave structure, preparation method and LED epitaxial wafer

Abstract

The embodiment of the application discloses a recessed structure patterned substrate, a preparation method and an LED epitaxial wafer. The preparation method of the recessed structure patterned substrate comprises the following steps: providing a substrate, forming a photoresist layer on the surface of the substrate, and forming a photoresist column mask through a pattern transfer technology, wherein the photoresist column mask is recessed away from the surface of the substrate; and performing patternization on the substrate according to the photoresist column mask to form a plurality of protruding microstructures, wherein the plurality of protruding microstructures are located on one side surface of the substrate, the plurality of protruding microstructures are recessed away from the surface of the substrate, and a recessed area is formed. By using the above method, a periodic recessed structure patterned substrate can be prepared, the plurality of protruding microstructures in the recessed structure patterned substrate are recessed away from the surface of the substrate, the propagation path of light can be effectively improved in the recessed structure patterned substrate, the number of refraction and reflection of light is increased, the light emission efficiency of an LED chip is improved, and the brightness of the LED chip 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 with concave structures, a preparation method and an LED epitaxial wafer. BACKGROUND

[0002] Due to the difference in reflection coefficients between the epitaxial layer and the sapphire substrate, the composite structure of the epitaxial layer and the sapphire substrate has low light extraction efficiency, most of the light cannot be emitted, and a large number of photons are converted into heat energy, thereby reducing the performance, service life and reliability of the device.

[0003] At present, the patterned sapphire substrate has a significant effect on improving the quality of epitaxial material and increasing the light extraction efficiency of the device, but the patterns of the patterned sapphire substrate are generally three-dimensional patterns in the shape of pyramids, which rely on the refraction and reflection of the conical surface of the pyramid shape to increase the light extraction efficiency. If you want to improve the light extraction efficiency, you need to make the three-dimensional pattern in the shape of pyramids as dense as possible, but since the sapphire substrate is hard and difficult to etch, it is difficult to control the etching depth and precision when the pattern distribution is dense. SUMMARY

[0004] Embodiments of the present application provide a patterned substrate with concave structures, a preparation method and an LED epitaxial wafer to improve the propagation path of light in the concave structure, increase the number of refraction and reflection of light, and improve the light extraction efficiency of the LED chip.

[0005] In a first aspect, embodiments of the present application provide a preparation method of a patterned substrate with concave structures, comprising:

[0006] providing a substrate, forming a photoresist layer on the surface of the substrate, and forming a photoresist column mask from the photoresist layer by pattern transfer technology, wherein the photoresist column mask is recessed away from the surface of the substrate;

[0007] According to the photoresist column mask, the substrate is patterned to form a plurality of protruding microstructures, wherein the plurality of protruding microstructures are located on one side surface of the substrate, the plurality of protruding microstructures are recessed away from the surface of the substrate, and a recessed area is formed.

[0008] Optionally, the method of providing a substrate, forming a photoresist layer on the surface of the substrate, and forming a photoresist column mask from the photoresist layer by pattern transfer technology comprises:

[0009] forming a photoresist layer on the substrate, and placing a mask above the photoresist layer, wherein the mask comprises a partially transparent area and a fully transparent area;

[0010] forming the photoresist column mask on the area corresponding to the partial light-transmitting region on the photoresist layer by a pattern transfer technology.

[0011] Optionally, the light-transmitting property of the partial light-transmitting region gradually decreases from the central region to the edge region.

[0012] Optionally, the light-transmitting property of the central region and the edge region ranges from 3% to 5%.

[0013] Optionally, after forming the photoresist column mask on the area corresponding to the partial light-transmitting region on the photoresist layer by a pattern transfer technology, the method further comprises:

[0014] performing a heating treatment on the photoresist column mask in a vacuum to adjust the degree of concave of the photoresist column mask away from the surface of the substrate.

[0015] Optionally, performing a heating treatment on the photoresist column mask in a vacuum to adjust the degree of concave of the photoresist column mask away from the surface of the substrate, comprises:

[0016] performing a heating treatment on the photoresist column mask in a vacuum to adjust the ratio of the depth of concave of the photoresist column mask in a first direction away from the surface of the substrate to the height of the photoresist column mask in the first direction, wherein the first direction is perpendicular to the surface of the substrate, ranges from 1% to 10%.

[0017] Optionally, the pressure range of the heating treatment on the photoresist column mask in a vacuum is 2.5mT-3mT, the temperature range is 90°C-100°C, and the time range is 600s-720s.

[0018] Optionally, after patterning the substrate according to the photoresist column mask to form a plurality of convex microstructures, the method further comprises:

[0019] forming a plurality of heterogeneous microstructures, wherein the heterogeneous microstructures are arranged one-to-one with the convex microstructures, and at least part of the heterogeneous microstructures fill the concave regions of the plurality of convex microstructures.

[0020] Optionally, the heterogeneous microstructures are first shape heterogeneous microstructures, second shape heterogeneous microstructures, or third shape heterogeneous microstructures.

[0021] The first shape heterogeneous microstructures are all filled in the concave regions, and the side surface of the first shape heterogeneous microstructures away from the substrate is parallel to the plane where the substrate is located.

[0022] The second-shaped heterogeneous microstructure includes a first part and a second part. The surface of the first part away from the substrate and the surface of the second part close to the substrate are attached. The first part is completely filled in the recessed area, and the second part is a cone-shaped protrusion structure.

[0023] The third-shaped heterogeneous microstructure includes a third part and a fourth part. The third part completely fills the recessed area, and the surface of the third part away from the substrate is parallel to the plane where the substrate is located. The fourth part surrounds the protruding microstructure in a direction parallel to the plane where the substrate is located. The surface of the fourth part away from the substrate is parallel to the plane where the substrate is located and is flush with the surface of the third part away from the substrate.

[0024] Multiple heterogeneous microstructures are formed, each corresponding to one of the protruding microstructures, and at least a portion of the heterogeneous microstructures fills the recessed regions of the multiple protruding microstructures, including:

[0025] A heterogeneous layer is deposited on the surface of the substrate on which the plurality of protruding microstructures are formed, the heterogeneous layer covering the protruding microstructures;

[0026] The heterogeneous layer is patterned to form a first-shaped heterogeneous microstructure, a second-shaped heterogeneous microstructure, or a third-shaped heterogeneous microstructure.

[0027] Secondly, embodiments of the present invention also provide a patterned substrate with a concave structure, which is prepared by the method for preparing a patterned substrate with a concave structure as described in any one of the first aspects.

[0028] Thirdly, embodiments of the present invention also provide an LED epitaxial wafer, including a patterned substrate with a concave structure as described in any of the second aspects.

[0029] This invention provides a patterned substrate with a concave structure, a fabrication method, and an LED epitaxial wafer. The fabrication method of the patterned substrate with a concave structure includes: providing a substrate; forming a photoresist layer on the surface of the substrate; and forming a photoresist pillar mask by using a pattern transfer technique, wherein the surface of the photoresist pillar mask is concave away from the substrate; and patterning the substrate according to the photoresist pillar mask to form multiple raised microstructures, wherein the multiple raised microstructures are all located on one side of the substrate surface, and the surfaces of the multiple raised microstructures are concave away from the substrate, forming a concave region. Using the above method, a patterned substrate with a periodic concave structure can be fabricated, wherein the multiple raised microstructures are concave away from the substrate surface. In this patterned substrate with a concave structure, the light propagation path can be effectively improved, the number of refractions and reflections of light can be increased, the light emission efficiency of the LED chip can be improved, and the brightness of the LED chip can be enhanced. BRIEF DESCRIPTION OF DRAWINGS

[0030] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed to be used in the embodiments description will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without any creative effort based on these drawings.

[0031] Figure 1 is a flowchart of a preparation method of a patterned substrate with an inner recess structure provided by an embodiment of the present application;

[0032] Figure 2 is Figure 1 is a structural flowchart of the preparation method of the patterned substrate with the inner recess structure;

[0033] Figure 3 is a structural schematic diagram of a patterned substrate with an inner recess structure provided by an embodiment of the present application;

[0034] Figure 4 is a flowchart of another preparation method of a patterned substrate with an inner recess structure provided by an embodiment of the present application;

[0035] Figure 5 is Figure 4 is a structural flowchart of the preparation method of the patterned substrate with the inner recess structure;

[0036] Figure 6 is a structural schematic diagram of a mask provided by an embodiment of the present application;

[0037] Figure 7 is a flowchart of still another preparation method of a patterned substrate with an inner recess structure provided by an embodiment of the present application;

[0038] Figure 8 is Figure 7 is a structural flowchart of the preparation method of the patterned substrate with the inner recess structure;

[0039] Figure 9 - Figure 11 is a structural schematic diagram of another three patterned substrates with inner recess structures provided by an embodiment of the present application;

[0040] Figure 12 is a structural schematic diagram of an LED epitaxial wafer provided by an embodiment of the present application. DETAILED DESCRIPTION

[0041] The application will be described in further detail below with reference to the drawings and embodiments. It is to be understood that the specific embodiments described herein are merely illustrative of the present application and are not intended to limit the present application. It is also to be understood that, for the purpose of description, only the parts related to the present application are shown in the drawings rather than all the parts.

[0042] The terms used in the embodiments of the present application are merely used for the purpose of describing particular embodiments and are not intended to limit the present application. It should be noted that the terms "upper", "lower", "left", "right", and the like described in the embodiments of the present application are described in the angle shown in the drawings and should not be construed as limiting the embodiments of the present application. In addition, it should be understood in the context that when referring to one element being formed "on" or "under" another element, it can be directly formed "on" or "under" another element, or indirectly formed "on" or "under" another element through an intermediate element. The terms "first", "second", and the like are merely used for the purpose of description and do not represent any order, quantity, or importance, but are used to distinguish different components. For those skilled in the art, the specific meanings of the above terms in the present application can be understood according to the specific circumstances.

[0043] The term "comprising" and its variants used in the present application are open and include "but not limited to". The term "based on" is "at least partially based on". The term "one embodiment" means "at least one embodiment".

[0044] It should be noted that the concepts of "first", "second", and the like mentioned in the present application are only used to distinguish the corresponding content and are not used to limit the order or mutual dependency.

[0045] It should be noted that the modification of "one" or "multiple" mentioned in the present application is illustrative and not limiting, and those skilled in the art should understand that unless the context clearly indicates otherwise, it should be understood as "one or more".

[0046] Figure 1 is a flowchart of a preparation method of a patterned substrate with a concave structure provided by the embodiments of the present application, Figure 2 is Figure 1 is a structural flowchart of a preparation method of a patterned substrate with a concave structure, Figure 3 is a structural schematic diagram of a patterned substrate with a concave structure provided by the embodiments of the present application, as shown in Figure 1 , Figure 2 and Figure 3 , the preparation method of the patterned substrate with a concave structure comprises:

[0047] S110, providing a substrate, forming a photoresist layer on the surface of the substrate, and forming a photoresist column mask on the photoresist layer by a pattern transfer technology, wherein the photoresist column mask is recessed away from the surface of the substrate.

[0048] Specifically, referring to Figure 2 a) of the drawings, a substrate 10 is provided, which is a substrate with a smooth surface, i.e., the substrate 10 has a C surface with good quality, which can help the epitaxial crystal to form a crystal nucleus and grow into an epitaxial layer. The substrate 10 can be a sapphire substrate, etc., which is not limited here. The surface of the substrate 10 is cleaned with a mixed solution of sulfuric acid (H2SO4) solution and hydrogen peroxide (H2O2) solution, wherein the ratio of the sulfuric acid (H2SO4) solution and the hydrogen peroxide (H2O2) solution is between 3:1 and 7:1. Then, a photoresist layer is formed on the surface of the substrate 10, and the photoresist layer is formed into a photoresist column mask 21 by a pattern transfer technology, for example, photolithography or nanoimprint technology, etc. The photoresist column mask 21 is a pattern mask of the photoresist layer after pattern processing, and the pattern of the photoresist column mask 21 corresponds to the pattern of the microstructure on the patterned substrate. The photoresist column mask 21 is recessed away from the surface of the substrate 10, so the microstructure on the patterned substrate is also recessed away from the surface of the substrate 10.

[0049] S120, patterning the substrate according to the photoresist column mask to form a plurality of protruding microstructures, wherein the plurality of protruding microstructures are located on one side surface of the substrate, and the plurality of protruding microstructures are recessed away from the surface of the substrate to form a recessed area.

[0050] Specifically, referring to Figure 2b) figure, the step is according to photoresist glue column mask 21, the process of pattern transfer to substrate 10, for example, can adopt dry or wet etching process, and substrate 10 is etched to complete patterning, for example, dry etching, adopts boron trichloride (BCl3) gas as main etching gas, the flow of boron trichloride (BCl3) gas is 80sccm-200sccm, and adopts trifluoromethane (CHF3) gas as auxiliary gas, the flow of trifluoromethane (CHF3) gas is 5sccm-22sccm, and, etching upper electrode etching power is 1000W-1400W, etching lower electrode etching power is 300W-800W, etching cavity pressure is 1.5mT-3mT, and etching time is 10min-45min. Multiple protruding microstructures 11 formed by pattern transfer are all located on the surface of substrate 10 on one side and are integrally formed with substrate 10, multiple protruding microstructures 11 are of the same material and have the same refractive index as substrate 10, the surface of multiple protruding microstructures 11 away from substrate 10 is recessed, forming recessed area 12, the propagation path of light can be effectively improved in the protruding microstructure 11, thereby increasing the refractive and reflective times of light, for example, recessed area 12 can be a reverse conical shape, and recessed area 12 can also be a hemispherical shape, which is not limited here.

[0051] With reference to the foregoing Figure 3 The recessed structure patterned substrate prepared by the preparation method of the recessed structure patterned substrate provided by the embodiments of the present application comprises: a substrate 10; and multiple protruding microstructures 11 integrally formed with the substrate 10 and located on one side of the surface of the substrate 10, wherein the surface of the multiple protruding microstructures 11 away from the substrate 10 is recessed, forming a recessed area 12. Optionally, the bottom surface diameter of the multiple protruding microstructures 11 ranges from 0.5 μm to 20 μm, and the height of the multiple protruding microstructures 11 ranges from 0.8 μm to 5 μm.

[0052] The technical scheme in the embodiments of the present application first provides a substrate, forms a photoresist layer on the surface of the substrate, and forms a photoresist glue column mask by a pattern transfer technology, wherein the surface of the photoresist glue column mask away from the substrate is recessed, then the substrate is patterned according to the photoresist glue column mask, and multiple protruding microstructures are formed, wherein the multiple protruding microstructures are all located on one side of the surface of the substrate, and the surface of the multiple protruding microstructures away from the substrate is recessed, forming a recessed area. By using the above method, a periodic recessed structure patterned substrate can be prepared, wherein the surface of the multiple protruding microstructures away from the substrate is recessed, the propagation path of light can be effectively improved in the recessed structure patterned substrate, the refractive and reflective times of light are increased, the light emission efficiency of the LED chip is improved, and the brightness of the LED chip is improved.

[0053] Figure 4is a flowchart of another preparation method of a graphic substrate with an inner recess structure provided by an embodiment of the present application, Figure 5 is Figure 4 is a structural flowchart of the preparation method of the graphic substrate with an inner recess structure, and the embodiment is optimized on the basis of the above-mentioned embodiment. Optionally, a substrate is provided, a photoresist layer is formed on the surface of the substrate, and the photoresist layer is formed into a photoresist column mask through a pattern transfer technology, including:

[0054] forming a photoresist layer on the substrate, and placing a mask plate above the photoresist layer, wherein the mask plate includes a partially transparent area and a fully transparent area;

[0055] forming a photoresist column mask in the area corresponding to the partially transparent area on the photoresist layer through a pattern transfer technology.

[0056] Further, after the photoresist column mask is formed in the area corresponding to the partially transparent area on the photoresist layer through the pattern transfer technology, the preparation method of the graphic substrate with an inner recess structure further includes:

[0057] heating the photoresist column mask in a vacuum to adjust the recess degree of the photoresist column mask away from the surface of the substrate.

[0058] For the details of the embodiment not described above, refer to the above-mentioned embodiments, the preparation method of the graphic substrate with an inner recess structure as shown in Figure 3 、 Figure 4 and Figure 5 includes:

[0059] S210, forming a photoresist layer on the substrate, and placing a mask plate above the photoresist layer, wherein the mask plate includes a partially transparent area and a fully transparent area.

[0060] Specifically, Figure 6 is a structural diagram of a mask plate provided by an embodiment of the present application, referring to Figure 5 a) and Figure 6A photoresist layer 20 is formed on a substrate 10. The photoresist can be either positive or negative. The photoresist layer 20 can be prepared using spin coating or spray coating processes, and its thickness can range from 1 μm to 6 μm. After the photoresist layer 20 is prepared, a mask 30 is placed above it. The mask 30 includes a partially transparent area 31 and a fully transparent area 32. For example, the interval between the partially transparent area 31 and the mask 30 can be 0.5 μm to 6 μm. If a positive photoresist is used to form the photoresist layer 20, the interval of the partially transparent area 31 determines the interval of the photoresist pillar mask 21. Optionally, the light transmittance of the partially transparent area 31 gradually decreases from the center to the edge, with the center of the partially transparent area 31 having the highest light transmittance. Then, after the photomask 30 undergoes exposure and development processes, the area on the photoresist layer 20 corresponding to the center of the partially transparent area 31 has a larger degree of concavity, while the area on the edge of the partially transparent area 31 has the lowest light transmittance. This allows for adjustment of the concavity shape of the surface of the photoresist layer 20 away from the substrate 10. Compared to a setting where the light transmittance of the partially transparent area 31 is the same from the center to the edge, the gradually decreasing light transmittance of the partially transparent area 31 from the center to the edge facilitates better adjustment of the concavity degree of the surface of the photoresist pillar mask 21 away from the substrate 10. Furthermore, the light transmittance range of the central and edge regions is 3%-5%. If the light transmittance of the central and / or edge regions is greater than 5%, it will affect the degree of depression of the surface of the photoresist pillar mask 21 away from the substrate 10 and the side formation shape of the photoresist pillar mask 21, thereby affecting the subsequent pattern transfer process.

[0061] S220. A photoresist pillar mask is formed in the area corresponding to a portion of the light-transmitting area on the photoresist layer using pattern transfer technology.

[0062] Specifically, refer to Figure 5 As shown in Figure b), a positive photoresist is coated on the surface of the substrate 10 to form a photoresist layer 20. Then, the mask 30 undergoes exposure and development processes in sequence. Through pattern transfer technology, a photoresist pillar mask 21 with periodic arrangement is formed on the photoresist layer 20. The position and number of the photoresist pillar mask 21 correspond to the partial light-transmitting area 31. For example, the photoresist layer 20 is exposed by the mask 30, and then the soluble photoresist is removed by the development step, that is, the photoresist layer 20 is patterned, and the pattern of the mask 30 is transferred to the photoresist layer 20 to form the photoresist pillar mask 21.

[0063] S230. The photoresist pillar mask is heated in a vacuum to adjust the degree of depression of the surface of the photoresist pillar mask away from the substrate.

[0064] Optionally, referring to the c) figure of Figure 5 , the heating treatment of the photoresist column mask 21 in the vacuum environment is used to adjust the recess degree of the photoresist column mask 21 away from the surface of the substrate 10, including: the heating treatment of the photoresist column mask 21 in the vacuum environment is used to adjust the ratio of the recess depth x1 of the photoresist column mask 21 in the first direction X to the height x0 of the photoresist column mask 21 in the first direction X to be in the range of 1%-10%, wherein the first direction X is perpendicular to the surface of the substrate 10. Specifically, referring to the c) figure of Figure 5 , the heating treatment of the photoresist column mask 21 in the vacuum environment, the gas pressure in the vacuum environment is reduced, in order to maintain the balance of pressure, the gas volume in the vacuum environment is increased, so that the photoresist column mask 21 is affected by the gas pressure, and in the heating environment, the solvent of the photoresist column mask 21 volatilizes, so that the recess degree of the photoresist column mask 21 away from the surface of the substrate 10 is increased, wherein the ratio of the recess depth x1 of the photoresist column mask 21 in the first direction X to the height x0 of the photoresist column mask 21 in the first direction X can be in the range of 1%-10%. It should be noted that the photoresist column mask 21 is a cylindrical structure, and the side of the photoresist column mask 21 is in the shape of a circular arc, which is not prone to recess in the vacuum environment and the heating environment.

[0065] Optionally, referring to the c) figure of Figure 5 , the pressure range of the heating treatment of the photoresist column mask 21 in the vacuum environment is 2.5mT-3mT, if the chamber pressure of the vacuum heating treatment is greater than 3mT, the etching uniformity of the heating treatment of the photoresist column mask 21 in the vacuum environment is poor, and if the chamber pressure of the vacuum heating treatment is less than 2.5mT, the process parameter control stability of the heating treatment of the photoresist column mask 21 in the vacuum environment is poor.

[0066] Optionally, referring to the c) figure of Figure 5 , the temperature range of the heating treatment of the photoresist column mask 21 in the vacuum environment is 90℃-100℃, if the temperature of the vacuum heating treatment is less than 90℃, the recess speed of the photoresist column mask 21 away from the side surface of the substrate 10 is slow when the heating treatment of the photoresist column mask 21 in the vacuum environment is performed, and if the temperature of the vacuum heating treatment is greater than 100℃, the side of the photoresist column mask 21 is prone to collapse or melt when the heating treatment of the photoresist column mask 21 in the vacuum environment is performed.

[0067] Optionally, referring to the c) figure of Figure 5c) the c) figure, the time range of the heat treatment of the photoresist column mask 21 in the vacuum is 600s-720s, if the etching time of the vacuum heat treatment is less than 600s, the side surface of the photoresist column mask 21 away from the substrate 10 is prone to less concave when the photoresist column mask 21 is heat treated in the vacuum, if the etching time of the vacuum heat treatment is greater than 720s, the side edge of the photoresist column mask 21 is prone to collapse when the photoresist column mask 21 is heat treated in the vacuum, the uniformity of the photoresist column mask 21 is poor, and the subsequent pattern transfer process is not conducive.

[0068] S240, according to the photoresist column mask, the substrate is patterned to form a plurality of convex microstructures, wherein the plurality of convex microstructures are located on one side surface of the substrate, and the surface of the plurality of convex microstructures away from the substrate is recessed to form a recessed area.

[0069] The technical scheme in the embodiment of the application first forms a photoresist layer on the substrate, and places a mask plate above the photoresist layer, wherein the mask plate includes a partially transparent area and a fully transparent area, then forms a photoresist column mask in the area corresponding to the partially transparent area of the photoresist layer by a pattern transfer technology, then heat treats the photoresist column mask in the vacuum to adjust the recessed degree of the surface of the photoresist column mask away from the substrate, and finally, according to the photoresist column mask, the substrate is patterned to form a plurality of convex microstructures, wherein the plurality of convex microstructures are located on one side surface of the substrate, and the surface of the plurality of convex microstructures away from the substrate is recessed to form a recessed area. By using the above method, the light transmission of the partially transparent area of the mask plate is set, which helps to adjust the recessed degree of the surface of the photoresist column mask away from the substrate, and the vacuum heat treatment of the photoresist column mask can further intensify the recessed degree of the surface of the photoresist column mask away from the substrate, so that a patterned substrate with good recessed area, convex microstructure and periodic concave structure can be prepared.

[0070] Figure 7 is a flow diagram of another method for preparing a patterned substrate with a concave structure provided in the embodiment of the application, Figure 8 is Figure 7 is a structural flow diagram of the method for preparing a patterned substrate with a concave structure, Figure 9 - Figure 11 is another three structural diagrams of a patterned substrate with a concave structure provided in the embodiment of the application, which is optimized on the basis of the above-mentioned embodiment. Optionally, after the substrate is patterned according to the photoresist column mask to form a plurality of convex microstructures, the method further includes:

[0071] a plurality of heterogeneous microstructures are formed, the heterogeneous microstructures are arranged one by one corresponding to the convex microstructures, and at least part of the heterogeneous microstructures is filled in the recessed areas of the plurality of convex microstructures.

[0072] The details of the embodiment not described above can refer to the above embodiments, such as Figure 7 - Figure 11 As shown in the figure, the preparation method of the patterned substrate of the inner recess structure includes:

[0073] S310, providing a substrate, forming a photoresist layer on the surface of the substrate, and forming a photoresist column mask by a pattern transfer technology, wherein the photoresist column mask is recessed away from the surface of the substrate.

[0074] S320, patterning the substrate according to the photoresist column mask to form a plurality of protruding microstructures, wherein the plurality of protruding microstructures are located on one side surface of the substrate, and the plurality of protruding microstructures are recessed away from the surface of the substrate to form a recessed area.

[0075] S330, forming a plurality of heterogeneous microstructures, the heterogeneous microstructures are one-to-one corresponding to the protruding microstructures, and at least part of the heterogeneous microstructures are filled in the recessed areas of the plurality of protruding microstructures.

[0076] Optionally, referring to Figure 9 - Figure 11 , the heterogeneous microstructure 40 is a first shape heterogeneous microstructure 41, a second shape heterogeneous microstructure 42, or a third shape heterogeneous microstructure 43; the first shape heterogeneous microstructure 41 is completely filled in the recessed area 12, and the first shape heterogeneous microstructure 41 is parallel to the plane where the substrate 10 is located away from one side surface of the substrate 10; the second shape heterogeneous microstructure 42 includes a first part 421 and a second part 422, the first part 421 is attached to the second part 422 away from one side surface of the substrate 10, the first part 421 is completely filled in the recessed area 12, and the second part 422 is a tapered protruding structure; the third shape heterogeneous microstructure 43 includes a third part 431 and a fourth part 432, the third part 431 is completely filled in the recessed area 12, and the third part 431 is parallel to the plane where the substrate 10 is located away from one side surface of the substrate 10, the fourth part 432 surrounds the protruding microstructure 11 in the direction parallel to the plane where the substrate 10 is located, the fourth part 432 is parallel to the plane where the substrate 10 is located away from one side surface of the substrate 10, and is flush with the third part 431 away from one side surface of the substrate 10; a plurality of heterogeneous microstructures 40 are formed, the heterogeneous microstructures 40 are one-to-one corresponding to the protruding microstructures 11, and at least part of the heterogeneous microstructures 40 are filled in the recessed areas 12 of the plurality of protruding microstructures 11, including:

[0077] S3301, depositing a heterogeneous layer on the surface of the substrate where the plurality of protruding microstructures are formed, and the heterogeneous layer covers the protruding microstructures.

[0078] Specifically, referring to Figure 8The surface of the substrate 10 is cleaned by a mixed solution of sulfuric acid (H2SO4) and hydrogen peroxide (H2O2) solution, wherein the ratio of the sulfuric acid (H2SO4) solution and the hydrogen peroxide (H2O2) solution is between 3:1 and 7:1. Then, a hetero layer is deposited on the surface of the substrate 10 on which the plurality of protruding microstructures 11 are formed, and the hetero layer is a film layer made of a hetero material, which is substantially a material different from the substrate 10 and an epitaxial layer material, for example, gallium nitride. Exemplarily, the hetero layer can be made of silicon dioxide material. The hetero layer covers the protruding microstructures 11. Exemplarily, the deposition of the hetero layer can be physical and chemical deposition processes such as magnetron sputtering and plasma enhanced chemical vapor deposition. The deposition thickness of the hetero layer can be in a range of 1 μm to 7 μm.

[0079] S3302, the hetero layer is patterned to form the first shape hetero microstructure, the second shape hetero microstructure, or the third shape hetero microstructure.

[0080] Specifically, referring to Figure 8 FIG. 8c and Figure 9 - Figure 11 , a positive photoresist is coated on the side surface of the hetero layer away from the substrate 10 to form a photoresist layer. Then, a mask is subjected to exposure and development processes in sequence to form a photoresist column mask. This step is a process of pattern transfer of the hetero layer according to the photoresist column mask, so as to etch the hetero layer to form a plurality of hetero microstructures 40 required finally. The hetero microstructures 40 are arranged one by one corresponding to the protruding microstructures 11, and at least part of the hetero microstructures 40 are filled in the recessed areas 12 of the plurality of protruding microstructures 11. Exemplarily, a dry etching or wet etching process can be used to etch the hetero layer to complete the patterning. Taking the dry etching as an example, boron trichloride (BCl3) gas is used as the main etching gas, the flow rate of the boron trichloride (BCl3) gas is 80 sccm to 200 sccm, trifluoromethane (CHF3) gas is used as the auxiliary gas, the flow rate of the trifluoromethane (CHF3) gas is 5 sccm to 22 sccm, the etching upper electrode etching power is 1000 W to 1400 W, the etching lower electrode etching power is 300 W to 800 W, the etching cavity pressure is 1.5 mT to 3 mT, and the etching time is 10 min to 45 min.

[0081] It should be noted that, as Figure 9 - Figure 11The three different shapes of the heterogeneous microstructures 40 shown can be prepared in this step by changing the mask pattern or setting different etching conditions, etc. For example, in the process of patterning the heterogeneous layer, the mask used to form the first shape heterogeneous microstructure 41 and the second shape heterogeneous microstructure 42 can be the same, and the etching time required to form the first shape heterogeneous microstructure 41 is greater than the etching time required to form the second shape heterogeneous microstructure 42, but the mask used to form the third shape heterogeneous microstructure 43 is different from the mask used to form the first shape heterogeneous microstructure 41 and / or the second shape heterogeneous microstructure 42, and the etching time required to form the third shape heterogeneous microstructure 43 can be different from the etching time used to form the first shape heterogeneous microstructure 41 and / or the second shape heterogeneous microstructure 42.

[0082] With reference to the foregoing Figure 9 - Figure 11 , the preparation method of the concave structure patterned substrate using the embodiment of the present application is used to prepare the concave structure patterned substrate, which also includes a plurality of heterogeneous microstructures 40, the heterogeneous microstructures 40 are arranged one-to-one with the protruding microstructures 11, and at least part of the heterogeneous microstructures 40 are filled in the recessed areas 12 of the plurality of protruding microstructures 11. Among them, the heterogeneous microstructures 40 are first shape heterogeneous microstructures 41, second shape heterogeneous microstructures 42 or third shape heterogeneous microstructures 43. As shown in Figure 9 the heterogeneous microstructures 40 are first shape heterogeneous microstructures 41, the first shape heterogeneous microstructures 41 are all filled in the recessed areas 12, and the side surface of the first shape heterogeneous microstructures 41 away from the substrate 10 is parallel to the plane where the substrate 10 is located. As shown in Figure 10 the heterogeneous microstructures 40 are second shape heterogeneous microstructures 42, the second shape heterogeneous microstructures 42 include a first part 421 and a second part 422, the first part 421 away from the side surface of the substrate 10 and the second part 422 close to the side surface of the substrate 10 are attached, the first part 421 is all filled in the recessed areas 12, and the second part 422 is a tapered protruding structure. As shown in Figure 11 the heterogeneous microstructures 40 are third shape heterogeneous microstructures 43, the third shape heterogeneous microstructures 43 include a third part 431 and a fourth part 432, the third part 431 is all filled in the recessed areas 12, and the side surface of the third part 431 away from the substrate 10 is parallel to the plane where the substrate 10 is located, the fourth part 432 surrounds the protruding microstructures 11 in the direction parallel to the plane where the substrate 10 is located, the side surface of the fourth part 432 away from the substrate 10 is parallel to the plane where the substrate 10 is located, and is flush with the side surface of the third part 431 away from the substrate 10.

[0083] The technical scheme in the embodiment of the present application first provides a substrate, forms a photoresist layer on the surface of the substrate, and forms a photoresist column mask by a pattern transfer technology, wherein the photoresist column mask is recessed away from the surface of the substrate, then the substrate is patterned according to the photoresist column mask to form a plurality of protruding microstructures, wherein the plurality of protruding microstructures are all located on one side surface of the substrate, the plurality of protruding microstructures are recessed away from the surface of the substrate to form recessed areas, and finally a plurality of heterogeneous microstructures are formed, the heterogeneous microstructures are arranged one by one corresponding to the protruding microstructures, and at least part of the heterogeneous microstructures is filled in the recessed areas of the plurality of protruding microstructures. By using the above method, at least part of the heterogeneous microstructures is filled in the recessed areas of the plurality of protruding microstructures, which is beneficial to increase the reflection and refraction times of light between the heterogeneous microstructures and the protruding microstructures, thereby improving the light emission efficiency of the LED chip and improving the brightness of the LED chip.

[0084] Based on the same inventive concept, the embodiment of the present application also provides an LED epitaxial wafer. Figure 12 is a structural schematic diagram of an LED epitaxial wafer provided by the embodiment of the present application, as shown in the figure, the LED epitaxial wafer comprises the patterned substrate 1 with the inner recess structure provided by any one of the embodiments of the present application, and further comprises an epitaxial layer 2 formed on the patterned substrate 1 with the inner recess structure. Figure 12

[0085] For forming the epitaxial layer 2 on the patterned substrate of different materials, different LED epitaxial wafer growth technologies are required, and for the patterned composite substrate provided by the embodiment of the present application, the epitaxial layer 2 in the LED epitaxial wafer can be a GaN, AlGaN epitaxial layer, etc. The LED epitaxial wafer has the same or similar beneficial effects as the patterned substrate 1 with the inner recess structure provided by the above embodiments, and details are not repeated here.

[0086] Note that the above are only 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 described herein, and those skilled in the art can make various obvious changes, re-adjustments, mutual combinations and substitutions without departing from the 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 method of preparing a patterned substrate of a concave structure, characterized by, The method comprises the following steps: providing a substrate, forming a photoresist layer on the surface of the substrate, and forming a photoresist column mask on the photoresist layer by a pattern transfer technology, wherein the photoresist column mask is recessed away from the surface of the substrate; performing a pattern on the substrate according to the photoresist column mask to form a plurality of protruding microstructures, wherein the plurality of protruding microstructures are located on one side surface of the substrate, and the plurality of protruding microstructures are recessed away from the surface of the substrate to form a recessed area; wherein the method of providing a substrate, forming a photoresist layer on the surface of the substrate, and forming a photoresist column mask on the photoresist layer by a pattern transfer technology comprises: forming a photoresist layer on the substrate, and placing a mask plate above the photoresist layer, wherein the mask plate comprises a partially transparent area and a fully transparent area, and the light transmittance of the partially transparent area gradually decreases from the center area to the edge area; forming the photoresist column mask on the corresponding area of the partially transparent area on the photoresist layer by a pattern transfer technology; after forming the photoresist column mask on the corresponding area of the partially transparent area on the photoresist layer by a pattern transfer technology, the method further comprises: performing a heating treatment on the photoresist column mask in a vacuum to adjust the recessed degree of the photoresist column mask away from the surface of the substrate, and the recessed degree of the photoresist column mask away from the surface of the substrate gradually decreases from the center area to the edge area.

2. The production method according to claim 1, characterized by, The light transmittance range of the center area and the edge area is 3%-5%.

3. The preparation method according to claim 1, characterized in that, The heating treatment on the photoresist column mask in a vacuum to adjust the recessed degree of the photoresist column mask away from the surface of the substrate comprises: performing a heating treatment on the photoresist column mask in a vacuum to adjust the ratio of the recessed depth of the photoresist column mask away from the surface of the substrate in the first direction to the height of the photoresist column mask in the first direction, and the ratio range is 1%-10%, wherein the first direction is perpendicular to the surface of the substrate.

4. The method of claim 1, wherein, The pressure range of the heating treatment on the photoresist column mask in a vacuum is 2.5mT-3mT, the temperature range is 90°C-100°C, and the time range is 600s-720s.

5. The preparation method according to claim 1, characterized in that, After performing a pattern on the substrate according to the photoresist column mask to form a plurality of protruding microstructures, the method further comprises: forming a plurality of heterogeneous microstructures, wherein the plurality of heterogeneous microstructures are arranged one by one corresponding to the plurality of protruding microstructures, and at least part of the plurality of heterogeneous microstructures fill the recessed area of the plurality of protruding microstructures.

6. The production method according to claim 5, wherein The heterogeneous microstructure is a first shape heterogeneous microstructure, a second shape heterogeneous microstructure, or a third shape heterogeneous microstructure; the first shape heterogeneous microstructure fills the recessed area, and the first shape heterogeneous microstructure is parallel to the plane where the substrate is located away from one side surface of the substrate; The second shape-heterogeneous microstructure comprises a first part and a second part, the first part is away from the one side surface of the substrate and the second part is close to the one side surface of the substrate, the first part is filled in the recessed area, and the second part is a conical protruding structure; The third shape-heterogeneous microstructure comprises a third part and a fourth part, the third part is filled in the recessed area, and the third part is parallel to the plane where the substrate is located away from the one side surface of the substrate, the fourth part surrounds the protruding microstructure in the direction parallel to the plane where the substrate is located, the fourth part is parallel to the plane where the substrate is located away from the one side surface of the substrate, and is flush with the third part away from the one side surface of the substrate; forming a plurality of heterogeneous microstructures, the heterogeneous microstructures are arranged one by one with the protruding microstructures, and at least part of the heterogeneous microstructures are filled in the recessed areas of the plurality of protruding microstructures, comprising: depositing a heterogeneous layer on the surface of the substrate where the plurality of protruding microstructures are formed, the heterogeneous layer covers the protruding microstructures; the heterogeneous layer is patterned to form a first shape-heterogeneous microstructure, a second shape-heterogeneous microstructure or a third shape-heterogeneous microstructure.

7. A patterned substrate of a concave structure, characterized by, The preparation method of the patterned substrate with the concave structure is prepared by using the preparation method of the patterned substrate with the concave structure according to any one of claims 1-6.

8. An LED epitaxial wafer, characterized by, The patterned substrate with the concave structure according to claim 7.

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