A patterned substrate and preparation method thereof, and LED chip

Abstract

The present invention discloses a patterned substrate and a preparation method thereof, and an LED chip, wherein the patterned substrate comprises: a substrate having a first surface side and a second surface side opposite to each other; and a plurality of table-shaped protruding structures, wherein the protruding structures are formed on the first surface side of the substrate, wherein the bottom area of ​​the protruding structures is larger than the top area of ​​the protruding structures, and the protruding structures are formed with a roughened microstructure on the top surface away from the substrate. The patterned substrate can randomly scatter light incident to the substrate, reduce the substrate's absorption of incident light, and improve light extraction efficiency; a stripe structure is also formed on the side wall of the second part of the protruding structure, and the stripe structure can also increase the reflectivity of the patterned structure to light, further improving the light extraction efficiency of the LED chip.

Description

Technical Field

[0001] The present invention relates to the technical field of semiconductor devices, and in particular to a patterned substrate and a preparation method thereof, and an LED chip. Background Art

[0002] In order to suppress the generation and slip of dislocations and obtain an epitaxial layer with low dislocation density and high crystal quality, patterned substrate technology has been developed in the prior art. Patterned substrate technology is achieved by making a pattern with a fine structure on the surface of a heterogeneous substrate, and then performing LED material epitaxy on the surface of this patterned substrate. The patterned substrate forms a scattered or diffuse reflection of light waves through its fine structure, increasing the probability of photons escaping, thereby improving the brightness of the LED. However, with the continuous updating of LED products, ordinary patterned substrates cannot meet the high brightness requirements of LED chips, and how to further improve the LED light extraction efficiency through patterned substrates has also become a technical difficulty. Summary of the invention

[0003] In order to solve at least one technical problem in the background technology, the present invention provides a patterned substrate and a preparation method thereof, and an LED chip, which can effectively improve the light extraction efficiency and enhance the brightness of the LED chip.

[0004] The technical solution adopted by the present invention is specifically as follows:

[0005] According to one aspect of the present invention, there is provided a patterned substrate, comprising:

[0006] a substrate having opposing first and second facing sides; and

[0007] A plurality of terrace-shaped protruding structures are formed on the first surface side of the substrate, the bottom area of ​​the protruding structure is larger than the top area of ​​the protruding structure, and a roughened microstructure is formed on the top surface of the protruding structure away from the substrate.

[0008] Optionally, in a direction parallel to the substrate, the maximum bottom area of ​​the roughened microstructure is smaller than the top area of ​​the protruding structure, and in a thickness direction of the substrate, the maximum height of the roughened microstructure is smaller than the height of the protruding structure.

[0009] Optionally, in a direction parallel to the substrate, the maximum span of the bottom surface of the roughened microstructure is less than 3 μm, and in a thickness direction of the substrate, the maximum height of the roughened microstructure is less than 3 μm.

[0010] Optionally, the diameter of the top surface of the protruding structure is between 0 and 3 μm, and the diameter of the bottom surface of the protruding structure is between 0.8 and 10 μm.

[0011] Optionally, the protruding structure includes a first portion and a second portion formed of different materials, and the second portion is located above the first portion.

[0012] Optionally, a cross-sectional area of ​​a top surface of the first portion is equal to a cross-sectional area of ​​a bottom surface of the second portion, and a height of the first portion is less than or equal to a height of the second portion.

[0013] Optionally, the protruding structure is formed as a truncated cone structure, and an included angle θ1 between the side surface and the bottom surface of the first portion is smaller than an included angle θ2 between the side surface and the bottom surface of the second portion.

[0014] Optionally, an included angle θ2 between the side surface and the bottom surface of the second portion is between 0°<θ2<90°, and an included angle θ1 between the side surface and the bottom surface of the first portion is between 0°<θ1<θ2.

[0015] Optionally, a stripe structure is disposed on the side wall of the second portion, and the stripe structure extends from a bottom surface side of the second portion close to the substrate to a top surface side away from the substrate.

[0016] Optionally, the width of the stripe structure along the circumferential direction of the protruding structure and the depth perpendicular to the sidewall of the second portion are less than the circumferential length of the protruding structure. Optionally, the width of the stripe structure along the circumferential direction of the protruding structure is 0 μm to 1 μm, and the depth of the stripe structure in the direction perpendicular to the sidewall of the second portion is 0 μm to 1 μm.

[0017] Optionally, the material of the substrate includes one of sapphire, SiC, Si and ZnO, and the material of the first part of the protruding structure is the same as that of the substrate.

[0018] Optionally, the material of the second part includes one or more of SiO2, Si3N4, ZnO2, Si, SiC, GaAs, Ti3O5, and TiO2.

[0019] According to another aspect of the present invention, there is provided a method for preparing a patterned substrate, comprising:

[0020] Providing a substrate having a first facing side and a second facing side opposite to each other;

[0021] forming a plurality of terrace-shaped protruding structures on the first surface side of the substrate;

[0022] The bottom size of the protruding structure is larger than the top size of the protruding structure, and a roughened microstructure is formed on the top surface of the protruding structure away from the substrate.

[0023] Optionally, before forming a plurality of raised graphic structures on the surface of the substrate, the method further includes:

[0024] forming an optical thin film layer on the surface of the substrate, wherein the material of the optical thin film layer is different from the material of the substrate;

[0025] Roughening the surface of the optical thin film layer to form a roughened microstructure on the surface of the optical thin film layer;

[0026] forming a mask layer on the optical thin film layer forming the roughened microstructure;

[0027] The optical thin film layer and a portion of the substrate are etched under the cover of the mask layer to form a protruding structure, wherein a portion of the substrate forms a first portion of the protruding structure and the optical thin film layer forms a second portion of the protruding structure.

[0028] Optionally, the surface of the optical thin film layer is roughened to form a roughened microstructure on the surface of the optical thin film layer, including:

[0029] The surface of the optical thin film layer is corroded by wet etching, and the etching time is controlled between 1S and 1000S.

[0030] Optionally, etching the optical thin film layer and a portion of the substrate under the cover of the mask layer to form a protruding structure, wherein a portion of the substrate forms a first portion of the protruding structure, and the optical thin film layer forms a second portion of the protruding structure, comprises:

[0031] The sidewall of the second part of the protruding structure is dry-etched using a selective etching gas while controlling the etching rate in the vertical direction to form a stripe structure on the sidewall of the second part, the stripe structure extending from the bottom surface of the second part close to the substrate to the top surface away from the substrate.

[0032] Optionally, a width of the stripe structure along the circumferential direction of the protruding structure and a depth perpendicular to the sidewall of the second portion are smaller than a circumferential length of the protruding structure.

[0033] The present invention also provides an LED chip, comprising a substrate and an epitaxial layer formed on the surface of the substrate, wherein the substrate is a patterned substrate as described in any of the above schemes, and the epitaxial layer comprises a first semiconductor layer, an active layer, and a second semiconductor layer of opposite type to the first semiconductor layer, which are sequentially formed on the first surface side of the patterned substrate having a pattern.

[0034] Compared with the prior art, the patterned substrate and its preparation method, and the LED chip of the present invention have at least the following beneficial effects:

[0035] The patterned substrate of the present invention comprises a substrate, the substrate having a first surface side and a second surface side opposite to each other; and a plurality of terraced protrusion structures, the protrusion structures are formed on the first surface side of the substrate, the bottom size of the protrusion structures is larger than the top size of the protrusion structures, and the protrusion structures are formed with a roughened microstructure on the top surface away from the substrate. The roughened microstructure is a completely irregular and randomly distributed microstructure, such as a mountain-shaped protrusion, etc. These microstructures can randomly scatter light incident to the substrate, reduce the substrate's absorption of the incident light, and improve the light extraction efficiency.

[0036] Furthermore, the raised structure in the present invention includes a first part and a second part, wherein a stripe structure is also formed on the side wall of the second part, and the stripe structure extends from the bottom surface of the second part close to the substrate to the top surface away from the substrate, which can increase the reflectivity of the raised structure to light and further improve the light extraction efficiency of the LED chip.

[0037] Furthermore, the angle between the side surface and the bottom surface of the first part is smaller than the angle between the side surface and the bottom surface of the second part, which can reduce the lattice dislocation of the epitaxial layer and improve the quality of the epitaxial layer crystal.

[0038] The method for preparing the patterned substrate and the LED chip comprising the patterned substrate of the present invention can also increase the light scattering rate and improve the light extraction efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 is a schematic structural diagram of a patterned substrate according to an embodiment of the present invention;

[0040] Figure 2 is a schematic structural diagram of a patterned substrate according to an embodiment of the present invention;

[0041] Figure 3 A flow chart of preparing the patterned substrate in an embodiment of the present invention;

[0042] Figure 4 It is a schematic diagram of a structure in which an optical thin film layer is formed on a surface of a substrate in an embodiment of the present invention;

[0043] Figure 5 A schematic diagram of the structure of roughening an optical thin film layer to form a roughened microstructure in an embodiment of the present invention;

[0044] Figure 6 It is a structural schematic diagram of forming a mask layer on an optical thin film layer in an embodiment of the present invention;

[0045] Figure 7 A schematic diagram of a structure for forming a patterned mask layer in an embodiment of the present invention;

[0046] Figure 8 It is a structural schematic diagram of etching the optical thin film layer and forming a stripe structure on the side wall of the second part of the protruding structure formed on the optical thin film layer in an embodiment of the present invention;

[0047] Fig. 9 It is a structural schematic diagram of etching a substrate to form a first part of a protruding structure in an embodiment of the present invention;

[0048] Fig.10 Schematic diagram of the structure of the LED chip in the embodiment of the present invention.

[0049] List of reference numerals:

[0050] 1 Patterned substrate

[0051] 100 Substrate

[0052] 110 Raised structure

[0053] 111 Part 1

[0054] 112 Part 2

[0055] 1121 Coarsened microstructure

[0056] 1122 Stripe Structure

[0057] 120 optical thin film layer

[0058] 130 Mask layer

[0059] 200 Epitaxial layer

[0060] 201 First semiconductor layer

[0061] 202 Active layer

[0062] 203 Second semiconductor layer

[0063] 301 First Electrode

[0064] 302 second electrode DETAILED DESCRIPTION

[0065] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present invention.

[0066] Example 1

[0067] This embodiment provides a patterned substrate, referring to Figure 1 The patterned substrate 1 includes a substrate 100 having a first surface side and a second surface side opposite to each other; and a plurality of terraced protrusion structures 110, wherein the protrusion structures 110 are formed on the first surface side of the substrate 100, wherein the bottom size of the protrusion structures 110 is larger than the top size of the protrusion structures 110, and the protrusion structures 110 are formed with a roughened microstructure 1121 on the top surface away from the substrate 100.

[0068] The substrate 100 includes one of sapphire, SiC, Si and ZnO, and a sapphire substrate is used in this embodiment. The protrusion structure 110 is formed on the first surface side of the substrate 100, and the bottom area of ​​the protrusion structure 110 is larger than the top area of ​​the protrusion structure 110. Optionally, the diameter of the top surface of the protrusion structure 110 is between 0 and 3 μm, and the diameter of the bottom surface of the protrusion structure 110 is between 0.8 and 10 μm.

[0069] The roughened microstructure 1121 is arranged on the top surface of the protruding structure 110 away from the substrate 100. The roughened microstructure 1121 is formed by corrosion or pressing, and is formed into a completely randomly distributed and irregular maze structure. Optionally, in the direction parallel to the substrate 100, the maximum area of ​​the bottom of the roughened microstructure 1121 is much smaller than the top area of ​​the protruding structure 110, and in the thickness direction of the substrate 100, the maximum height of the roughened microstructure 1121 is much smaller than the height of the protruding structure 110. Optionally, in the direction parallel to the substrate 100, the maximum span of the bottom surface of the roughened microstructure 1121 is less than 3 μm, and in the thickness direction of the substrate 100, the maximum height of the roughened microstructure 1121 is less than 3 μm. Since the roughened microstructure 1121 has different shapes, it can scatter light incident at random angles, thereby greatly increasing the scattering efficiency of the incident light, reducing the absorption of the incident light by the substrate, and improving the light extraction efficiency.

[0070] In an optional embodiment, the protruding structure 110 includes a first portion 111 and a second portion 112 formed above the first portion 111, and the roughened microstructure 1121 is formed on the surface of the second portion 112. The materials of the first portion 111 and the second portion 112 of the protruding structure 110 are different. Optionally, the material of the first portion 111 is the same as the material of the substrate 100, and the material of the second portion 112 includes one or more of SiO2, Si3N4, ZnO2, Si, SiC, GaAs, Ti3O5, and TiO2. Optionally, the cross-sectional area of ​​the top surface of the first portion 111 is equal to the cross-sectional area of ​​the bottom surface of the second portion 112, for example, the diameter is between 0.5-6μm. The height of the first portion 111 is less than or equal to the height of the second portion 112, for example, the height of the first portion 111 is between 0μm-3μm; the height of the second portion 112 of the protruding structure 110 is between 0.5μm-10μm.

[0071] The angle between the side and bottom of the first part 111 is smaller than the angle between the side and bottom of the second part 112. Optionally, the angle θ2 between the side and bottom of the second part 112 is between 0°<θ2<90°, and the angle θ1 between the side and bottom of the first part 111 is between 0°<θ1<θ2. It should be noted that the angle between the side and bottom of the first part 111 is smaller than the angle between the side and bottom of the second part 112, which can reduce the lattice dislocation of the epitaxial layer 200 subsequently grown on the patterned substrate 1 and improve the quality of the crystal of the epitaxial layer 200.

[0072] In this embodiment, a roughened microstructure is formed on the top surface of the protruding structure. The roughened microstructure is a completely irregular microstructure, so that the light incident to the substrate can be randomly scattered, reducing the absorption of the incident light by the substrate and improving the light extraction efficiency. The angle between the side surface and the bottom surface of the first part is smaller than the angle between the side surface and the bottom surface of the second part, which can reduce the lattice dislocation of the epitaxial layer and improve the quality of the epitaxial layer crystal.

[0073] Example 2

[0074] This embodiment provides a patterned substrate, referring to Figure 2 The similarities between the substrate and the embodiment 1 are not described here, and the difference is that:

[0075] In this embodiment, a stripe structure 1122 is provided on the sidewall of the second portion 112 of the protruding structure, and the stripe structure 1122 extends from the bottom surface of the second portion 112 close to the substrate 100 to the top surface away from the substrate 100. In addition, the width of the stripe structure 1122 along the circumferential direction of the protruding structure 110 and the depth perpendicular to the sidewall of the second portion 112 are much smaller than the circumferential length of the protruding structure 110. In this embodiment, the width of the stripe structure 1122 along the circumferential direction of the protruding structure 110 is 0 μm to 1 μm, and the depth of the stripe structure 1122 in the direction perpendicular to the sidewall of the second portion 112 is 0 μm to 1 μm.

[0076] It should be noted that the stripe structure 1122 in this embodiment is formed by the interval between the groove and the protrusion, and the width of the stripe structure 1122 refers to the width of the groove or the protrusion, and the widths of the two are equal. The arrangement of the stripe structure 1122 can increase the light emitting area of ​​the patterned substrate 1, thereby increasing the reflectivity of the patterned substrate and the probability of light emission, and improving the light emitting efficiency of the LED.

[0077] A stripe structure is also formed on the side wall of the second portion of the protruding structure in this embodiment. The stripe structure can also increase the reflectivity of the protruding structure to light, thereby further improving the light extraction efficiency of the LED chip.

[0078] Example 3

[0079] This embodiment provides a method for preparing a patterned substrate. Figure 3 .

[0080] S101: providing a substrate, wherein the substrate has a first surface side and a second surface side opposite to each other;

[0081] Reference Figure 4 , a substrate 100 is provided. The material of the substrate 100 includes one of sapphire, SiC, Si and ZnO. In this embodiment, a sapphire substrate is used.

[0082] Also refer to Figure 4 An optical film layer 120 is formed on the substrate 100. The thickness of the optical film layer 120 is between 0.1 μm and 15 μm. Specifically, the optical film layer 120 can be formed by chemical vapor deposition. For example, the chemical vapor deposition can be a plasma enhanced chemical vapor deposition process (PECVD).

[0083] As an example, the material of the optical thin film layer 120 includes one or more of SiO2, Si3N4, ZnO2, Si, SiC, GaAs, Ti3O5, and TiO2.

[0084] Reference Figure 5 ,right Figure 4 The surface of the optical film layer 120 obtained in the step of roughening is subjected to a roughening treatment to form a roughened microstructure 1121 on the surface of the optical film layer 120. The roughened microstructure 1121 is formed into a completely irregular and randomly distributed microstructure, and in the direction parallel to the substrate 100, the maximum area of ​​the bottom of the roughened microstructure 1121 is much smaller than the top area of ​​the protruding structure 110, and in the thickness direction of the substrate 100, the maximum height of the roughened microstructure 1121 is much smaller than the height of the protruding structure 110. Specifically, in the direction parallel to the substrate 100, the maximum span of the bottom surface of the roughened microstructure 1121 is less than 3 μm, and in the thickness direction of the substrate 100, the maximum height of the roughened microstructure 1121 is less than 3 μm.

[0085] The surface of the optical film layer 120 is corroded by wet etching, and the etching time is controlled to be between 1S and 1000S to obtain the above-mentioned roughened microstructure 1121. Specifically, HF acid with a concentration of 1% can be used to etch the optical film layer 120. It should be noted that the roughened microstructure 1121 can also be achieved by other methods such as pressing, which will not be repeated here.

[0086] Reference Figure 6After forming the roughened microstructure 1121 on the surface of the optical film layer 120, the method further includes: forming a mask layer 130 on the surface of the optical film layer 120 formed with the roughened microstructure 1121. The mask layer 130 used in this embodiment is a photoresist, and the thickness of the formed photoresist is 0.5 μm-5 μm.

[0087] Reference Figure 7 , etching the photoresist layer to form a patterned photoresist layer, wherein the patterned photoresist layer is formed into a plurality of cylindrical photoresists, wherein the distance between two adjacent cylindrical photoresists is between 0.5 μm and 10 μm, and the bottom diameter of a single cylindrical photoresist is between 0.5 μm and 9.5 μm.

[0088] S102: forming a plurality of terrace-shaped protruding structures on the first surface side of the substrate; wherein the bottom size of the protruding structure is larger than the top size of the protruding structure, and a roughened microstructure is formed on the top surface of the protruding structure away from the substrate.

[0089] Reference Figure 8 Under the shielding of the patterned photoresist, the lower optical film layer 120 is etched to a depth of 0.5 μm-10 μm to form a truncated cone structure; the etched optical film layer 120 is formed into the second part 112 of the protruding structure 110 .

[0090] Reference Fig. 9 , the lower substrate 100 is continuously etched to a depth of 0 μm-3 μm to form a first portion 111 of the protruding structure 110; during the etching process, the etching rate of the substrate 100 is controlled so that the angle between the side and bottom of the first portion 111 formed by the substrate 100 is smaller than the angle between the side and bottom of the second portion 112 formed by the optical thin film layer 120. In this embodiment, the first portion 111 is also formed as a truncated cone structure.

[0091] It should be noted that, during the etching process of the substrate 100 , the photoresist layer on the surface of the optical thin film layer 120 is retained to protect the roughened microstructure 1121 on the surface thereof.

[0092] After etching the substrate 100 to form the truncated cone-shaped first portion 111, the process further includes: removing the photoresist layer on the surface of the optical film layer 120 to obtain Figure 1 The patterned substrate 1 is shown.

[0093] The method for preparing the patterned substrate described in this embodiment includes the patterned substrate described in Example 1, which can also increase the reflection of light incident on the substrate surface, improve the light extraction efficiency of the LED chip, and at the same time ensure the formation quality of the epitaxial layer and improve the luminous brightness.

[0094] Example 4

[0095] This embodiment also provides a method for preparing a patterned substrate, which is similar to that in Embodiment 3 and will not be described in detail here. The difference is that:

[0096] In step S102, refer to Figure 8 , under the shielding of the patterned photoresist, the lower optical film layer 120 is etched to a depth of 0.5 μm-10 μm to form a truncated cone structure; while forming the truncated cone structure, the sidewall of the truncated cone structure is dry-etched by a selective etching gas, and the etching rate in the vertical direction is increased to form a stripe structure 1122 with grooves and protrusions alternating on the sidewall of the truncated cone structure. The stripe structure 1122 extends from the bottom surface of the second part 112 close to the substrate 100 to the top surface away from the substrate 100. In addition, the width of the stripe structure 1122 along the circumferential direction of the protruding structure 110 and the depth perpendicular to the sidewall of the second part 112 are much smaller than the circumferential length of the protruding structure 110. In this embodiment, the width of the stripe structure 1122 along the circumferential direction of the protruding structure 110 is 0 μm to 1 μm, and the depth of the stripe structure in the direction perpendicular to the sidewall of the second part 112 is 0 μm to 1 μm.

[0097] After etching the substrate 100 to form the truncated cone-shaped first portion 111, the photoresist layer on the surface of the optical film layer 120 is removed to obtain Figure 2 The patterned substrate 1 is shown.

[0098] The method for preparing the patterned substrate described in this embodiment includes the patterned substrate described in Example 2, which can also increase the reflectivity of the protruding structure to light, and further improve the light extraction efficiency of the LED chip.

[0099] Example 5

[0100] This embodiment discloses an LED chip, referring to Fig.10 The LED chip includes a substrate 100 and an epitaxial layer 200 formed on the surface of the substrate 100 . The substrate 100 is the patterned substrate 100 in Example 1 or Example 2. The epitaxial layer 200 is formed on a side of the patterned substrate 100 having a protruding structure 110 .

[0101] Specifically, refer to Fig.10 , an epitaxial layer 200 including a first semiconductor layer 201, an active layer 202, and a second semiconductor layer 203 of opposite type to the first semiconductor layer 201 is sequentially included on the patterned side of the patterned substrate; optionally, a second electrode 302 is formed on the second semiconductor layer 203, and a first electrode 301 is formed on the first semiconductor layer 201. Optionally, the first semiconductor layer 201 may be an N-type gallium nitride layer, and the second semiconductor layer 203 may be a P-type gallium nitride layer.

[0102] This embodiment also provides a method for preparing the above-mentioned LED chip, including: providing a substrate 100, forming a plurality of raised protrusion structures 110 on the surface of the substrate 100 to form a patterned substrate 100 as described in Embodiment 1 or Embodiment 2;

[0103] An epitaxial layer 200 is formed on one side of the patterned substrate 100 having the protruding structure 110 . The epitaxial layer 200 includes a first semiconductor layer 201 , an active layer 202 , and a second semiconductor layer 203 of opposite type to the first semiconductor layer 201 .

[0104] Since the LED chip in this embodiment includes the patterned substrate described in Embodiment 1 or 2, the quality of the epitaxial layer and the light extraction efficiency of the LED chip in this embodiment are greatly improved, and the brightness is significantly increased.

[0105] In summary, the patterned substrate of the present invention includes a substrate having a first surface side and a second surface side opposite to each other; and a plurality of terraced protrusion structures, the protrusion structures are formed on the first surface side of the substrate, the bottom size of the protrusion structures is larger than the top size of the protrusion structures, and the protrusion structures are formed with a roughened microstructure on the top surface away from the substrate. The roughened microstructure is a completely irregular and randomly distributed microstructure, such as a mountain-shaped protrusion, etc. These microstructures can randomly scatter light incident to the substrate, reduce the substrate's absorption of incident light, and improve light extraction efficiency.

[0106] Furthermore, the raised structure in the present invention includes a first part and a second part, wherein a stripe structure is also formed on the side wall of the second part, and the stripe structure extends from the bottom surface of the second part close to the substrate to the top surface away from the substrate, which can increase the reflectivity of the raised structure to light and further improve the light extraction efficiency of the LED chip.

[0107] Furthermore, the angle between the side surface and the bottom surface of the first part is smaller than the angle between the side surface and the bottom surface of the second part, which can reduce the lattice dislocation of the epitaxial layer and improve the quality of the epitaxial layer crystal.

[0108] The method for preparing the patterned substrate and the LED chip comprising the patterned substrate of the present invention can also increase the light scattering rate and improve the light extraction efficiency.

[0109] This specific embodiment is only an explanation of the present invention, not a limitation of the present invention. Those skilled in the art may make modifications to the present embodiment as needed after reading this specification. However, as long as it is within the scope of the claims of the present invention, it shall be protected by the patent law.

Claims

1. A patterned substrate, It is characterized in that include: a substrate having opposing first and second facing sides; and A plurality of terrace-shaped convex structures, wherein the convex structures are formed on the first surface side of the substrate, the bottom area of ​​the convex structures is larger than the top area of ​​the convex structures, and the convex structures are formed with a roughened microstructure on the top surface away from the substrate; the roughened microstructure is formed by wet etching, the roughened microstructure is a completely irregular and randomly distributed microstructure, the maximum span of the bottom surface of the roughened microstructure in the direction parallel to the substrate is less than 3 μm, and the maximum height of the roughened microstructure in the thickness direction of the substrate is less than 3 μm; the convex structure comprises a first part and a second part formed above the first part, a stripe structure is arranged on the side wall of the second part, the stripe structure extends from the second part close to the bottom surface of the substrate to the top surface away from the substrate, and the angle θ between the side surface and the bottom surface of the first part is 1 is smaller than the angle θ between the side and bottom of the second portion 2 .

2. The patterned substrate according to claim 1, It is characterized in that In a direction parallel to the substrate, the maximum bottom area of ​​the roughened microstructure is smaller than the top area of ​​the protruding structure, and in a thickness direction of the substrate, the maximum height of the roughened microstructure is smaller than the height of the protruding structure.

3. The patterned substrate according to claim 1, It is characterized in that The diameter of the top surface of the protruding structure is between 0 and 3 μm, and the diameter of the bottom surface of the protruding structure is between 0.8 and 10 μm.

4. The patterned substrate according to claim 1, It is characterized in that The protruding structure includes a first portion and a second portion formed of different materials, and the second portion is located above the first portion.

5. The patterned substrate according to claim 1 or 4, It is characterized in that The cross-sectional area of ​​the top surface of the first portion is equal to the cross-sectional area of ​​the bottom surface of the second portion, and the height of the first portion is less than or equal to the height of the second portion.

6. The patterned substrate according to claim 5, It is characterized in that The protruding structure is formed as a truncated cone structure.

7. The patterned substrate according to claim 6, It is characterized in that The angle θ between the side surface and the bottom surface of the second part 2 Between 0°<θ 2 <90°, the angle θ between the side and bottom of the first part 1 Between 0°<θ 1 <θ 2 .

8. The patterned substrate according to claim 1, It is characterized in that The width of the stripe structure along the circumferential direction of the protruding structure and the depth perpendicular to the sidewall of the second portion are smaller than the circumferential length of the protruding structure.

9. The patterned substrate according to claim 8, It is characterized in that The width of the stripe structure along the circumferential direction of the protruding structure is 0 μm-1 μm, and the depth of the stripe structure in a direction perpendicular to the side wall of the second portion is 0 μm-1 μm.

10. The patterned substrate according to claim 4, It is characterized in that The material of the substrate includes one of sapphire, SiC, Si and ZnO, and the material of the first part of the protruding structure is the same as that of the substrate.

11. The patterned substrate according to claim 1 or 4, It is characterized in that The material of the second part includes SiO 2 、Si 3 N 4 、ZnO 2 、Si、SiC、GaAs、Ti 3 O 5 、TiO 2 One or more of .

12. A method for preparing a patterned substrate, It is characterized in that include: providing a substrate having a first facing side and a second facing side opposite to each other; forming a plurality of terrace-shaped protruding structures on the first surface side of the substrate; The bottom size of the protruding structure is larger than the top size of the protruding structure, and a roughened microstructure is formed on the top surface of the protruding structure away from the substrate, the roughened microstructure is formed by wet etching, the roughened microstructure is a completely irregular and randomly distributed microstructure, and in a direction parallel to the substrate, the maximum span of the bottom surface of the roughened microstructure is less than 3 μm, and in the thickness direction of the substrate, the maximum height of the roughened microstructure is less than 3 μm; the protruding structure includes a first part and a second part formed above the first part, a stripe structure is arranged on the side wall of the second part, and the stripe structure extends from the bottom surface side of the second part close to the substrate to the top surface side away from the substrate, and the angle θ between the side surface of the first part and the bottom surface is 1 is smaller than the angle θ between the side and bottom of the second portion 2 .

13. The method for preparing a patterned substrate according to claim 12, It is characterized in that Before forming a plurality of raised graphic structures on the surface of the substrate, the method further comprises: forming an optical thin film layer on the surface of the substrate, wherein the material of the optical thin film layer is different from the material of the substrate; Performing a roughening treatment on the surface of the optical thin film layer to form a roughened microstructure on the surface of the optical thin film layer; forming a mask layer on the optical thin film layer forming the roughened microstructure; The optical thin film layer and a portion of the substrate are etched under the shielding of the mask layer to form the protruding structure, wherein a portion of the substrate forms a first portion of the protruding structure, and the optical thin film layer forms a second portion of the protruding structure.

14. The method for preparing a patterned substrate according to claim 13, It is characterized in that The surface of the optical film layer is roughened to form a roughened microstructure on the surface of the optical film layer, comprising: The surface of the optical thin film layer is corroded by wet etching, and the etching time is controlled between 1 s and 1000 s.

15. The method for preparing a patterned substrate according to claim 13, It is characterized in that The optical thin film layer and a portion of the substrate are etched under the cover of the mask layer to form the convex structure, wherein a portion of the substrate forms a first portion of the convex structure, and the optical thin film layer forms a second portion of the convex structure, comprising: The sidewall of the second part of the protruding structure is dry-etched using a selective etching gas, while controlling the etching rate in the vertical direction to form a stripe structure on the sidewall of the second part, wherein the stripe structure extends from the second part close to the bottom surface of the substrate to the top surface away from the substrate.

16. The method for preparing a patterned substrate according to claim 15, It is characterized in that The width of the stripe structure along the circumferential direction of the protruding structure and the depth perpendicular to the sidewall of the second portion are smaller than the circumferential length of the protruding structure.

17. An LED chip, It is characterized in that It includes a substrate and an epitaxial layer formed on the surface of the substrate, wherein the substrate is a patterned substrate as described in any one of claims 1 to 11, and the epitaxial layer includes a first semiconductor layer, an active layer, and a second semiconductor layer of opposite type to the first semiconductor layer, which are sequentially formed on a first surface side of the patterned substrate having a pattern.

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