Composite patterned substrate, led epitaxial wafer and method of fabrication

Abstract

The application discloses a composite patterned substrate, an LED epitaxial wafer and a preparation method. The composite patterned substrate comprises a substrate and a plurality of conical structures on one side surface of the substrate; the plurality of conical structures are arranged in a hexagon; the conical structure comprises a conical main body part and a filling part; the conical main body part comprises an apex, a conical surface and a bottom surface; the conical surface has six first arc-shaped grooves and six first arc-shaped protrusions; the first arc-shaped grooves are respectively located at positions of the conical surface aligned with six adjacent conical structures, and are arranged in a spaced manner with the first arc-shaped protrusions; the first arc-shaped grooves and the first arc-shaped protrusions are both extended from the apex to the bottom surface; and the filling part is filled in the first arc-shaped grooves. The application reduces the difference in C-face flatness of the composite patterned substrate in the dense and sparse pattern directions, improves the C-face flatness, reduces the probability of dislocation generation in the epitaxial growth process, and improves the light extraction efficiency.

Description

Technical Field

[0001] This invention relates to semiconductor technology, and more particularly to a composite patterned substrate, an LED epitaxial wafer, and a method for its fabrication. Background Technology

[0002] In the semiconductor manufacturing field, patterned substrates are widely used in the epitaxial growth process of light-emitting diodes (LEDs) to improve light extraction efficiency and reduce dislocation density in the epitaxial layer.

[0003] Traditional patterned sapphire substrates typically employ a periodically arranged protrusion structure. However, due to the inherent directionality of plasma etching, there is a significant difference in etching rates between the dense and sparse directions of the substrate pattern. This anisotropic etching results in uneven C-plane flatness and poor surface morphology consistency in the final substrate, affecting the crystal quality of subsequent epitaxial layers, increasing dislocation density, and reducing the luminous efficiency of LEDs.

[0004] Currently, existing technical solutions mainly improve the flatness of the C-surface by adjusting the gas ratio and radio frequency power, but it is still difficult to eliminate the difference in etching rate between the close-packed and sparse-packed directions. Summary of the Invention

[0005] This invention provides a composite patterned substrate, an LED epitaxial wafer, and a preparation method to reduce the difference in C-plane flatness in the dense and sparse directions of the patterned substrate, improve C-plane flatness, reduce the probability of dislocation generation during epitaxial growth, and improve light extraction efficiency.

[0006] In a first aspect, the present invention provides a composite patterned substrate, comprising: a substrate and a plurality of conical structures located on one side surface of the substrate; the plurality of conical structures are arranged in a hexagonal pattern;

[0007] The conical structure includes a conical main body and a filling part. The conical main body includes a vertex, a conical surface, and a bottom surface. The conical surface has six first arc-shaped grooves and six first arc-shaped protrusions. The first arc-shaped grooves are respectively located at positions of the six adjacent conical structures aligned with the conical surface and are spaced apart from the first arc-shaped protrusions. Both the first arc-shaped grooves and the first arc-shaped protrusions extend from the vertex to the bottom surface.

[0008] The filling portion fills the first arc-shaped groove.

[0009] Optionally, the minimum length of the projection pattern of the first arc-shaped groove on the bottom surface in the radial direction of the bottom surface is L, and the maximum length of the bottom surface in the radial direction is R, where 0 < L: R / 2 ≤ 0.8.

[0010] Optionally, the center-to-center distance between the bottom surfaces of any two adjacent conical structures is 1 μm to 8 μm.

[0011] In a second aspect, the present invention also provides an LED epitaxial wafer, comprising a composite patterned substrate as described in any of the first aspects, and an epitaxial layer formed on the composite patterned substrate.

[0012] Thirdly, the present invention also provides a method for preparing a composite patterned substrate, for preparing a composite patterned substrate as described in any one of the first aspects, the method comprising:

[0013] Provide flat substrates;

[0014] A first photoresist layer is formed on the flat substrate;

[0015] The first photoresist layer is exposed and developed to obtain a plurality of first photoresist pillars; wherein the plurality of first photoresist pillars are arranged in a hexagonal shape, and the side of the first photoresist pillars has a plurality of second arc-shaped grooves, the second arc-shaped grooves being perpendicular to the surface of the flat substrate.

[0016] Using the first photoresist pillar as a mask, an etching process is employed under first etching conditions to etch the first photoresist pillar and the flat substrate, forming a substrate and a plurality of conical main bodies located on one side surface of the substrate; wherein, the plurality of conical main bodies are arranged in a hexagonal pattern; each conical main body includes a vertex, a conical surface, and a bottom surface, the conical surface having six first arc-shaped grooves and six first arc-shaped protrusions; the first arc-shaped grooves are respectively located at positions aligning with the six adjacent conical main bodies on the conical surface, and are spaced apart from the first arc-shaped protrusions; both the first arc-shaped grooves and the first arc-shaped protrusions extend from the vertex to the bottom surface;

[0017] A heterogeneous material is filled into the first arc-shaped groove of the cone-shaped main body to obtain a filled portion, which together with the cone-shaped main body forms a conical structure.

[0018] Optionally, the height of the first photoresist pillar is 1μm-3.8μm.

[0019] Optionally, the projection of the second arc-shaped groove of the first photoresist pillar in the height direction can be any one of a circular arc, a triangle, or a polygon.

[0020] Optionally, a heterogeneous material is filled into the first arc-shaped groove of the conical main body to obtain a filled portion, which forms a conical structure with the conical main body, including:

[0021] The heteromaterial is deposited on the side of the conical body portion away from the substrate, the heteromaterial filling the first arc-shaped groove and forming a heteromaterial layer on the side of the conical body portion away from the substrate;

[0022] A second photoresist layer is formed on the side of the heteromaterial layer facing away from the substrate;

[0023] The second photoresist layer is exposed and developed to obtain a plurality of second photoresist pillars; wherein the second photoresist pillars are cylindrical, and in the thickness direction of the substrate, the second photoresist pillars coincide with the center projection of the conical main body;

[0024] Using the second photoresist pillar as a mask, the second photoresist pillar and the heteromaterial layer are etched using an etching process and a second etching condition to obtain the filling portion, which together with the cone-shaped main body portion forms a cone structure.

[0025] Optionally, the etching process includes inductively coupled plasma dry etching. In the first etching conditions and the second etching conditions, the etching process pressure is 2.5 mTor, the upper RF electrode power is 1400 W, the lower RF electrode power is 400 W-750 W, the boron trichloride gas flow rate is 100 sccm, the CHF3 flow rate is 10-20 sccm, the He pressure is 4-6 Tor, and the cooler temperature is 10-25℃.

[0026] Optionally, a heterogeneous material is deposited on the side of the conical body facing away from the substrate, including:

[0027] The heteromaterial was deposited on the side of the conical body away from the substrate using plasma-enhanced chemical vapor deposition (PECVD) with SiH4 flow rate of 150-300 sccm, N2O flow rate of 1500-5000 sccm, N2 flow rate of 2000-3500 sccm, reaction chamber temperature of 250-350°C, and RF power of 150-350 W.

[0028] This invention provides a composite patterned substrate, an LED epitaxial wafer, and a fabrication method. By forming multiple hexagonally arranged conical structures on the substrate surface, space utilization is improved. Simultaneously, in the close-packed direction of the hexagonal arrangement, the conical main body of the conical structure is configured as a first arc-shaped groove structure, and in the sparse-packed direction, it is configured as a first arc-shaped protrusion structure. This effectively reduces the gap difference between adjacent conical structures in the close-packed and sparse-packed directions, thereby reducing the etching rate difference between the close-packed and sparse-packed directions during etching. This effectively improves the C-plane flatness of the composite patterned substrate, which is beneficial for epitaxial crystal growth and improves crystal quality. Furthermore, the first arc-shaped groove structure effectively increases the surface area of ​​the composite patterned substrate. In addition, a filling portion is formed at the location of the first arc-shaped groove in the conical main body, effectively reducing the probability of dislocation generation during epitaxial growth, optimizing the stress distribution of the epitaxial layer, and improving light extraction efficiency. Attached Figure Description

[0029] Figure 1 A side view of a composite patterned substrate provided in an embodiment of the present invention;

[0030] Figure 2 A top view of a composite patterned substrate provided in an embodiment of the present invention;

[0031] Figure 3 This is a schematic diagram of the structure of a cone-shaped main body provided in an embodiment of the present invention;

[0032] Figure 4 A top view of a cone-shaped main body with hexagonal arrangement provided in an embodiment of the present invention;

[0033] Figure 5 This is a schematic diagram of a conical structure provided in an embodiment of the present invention;

[0034] Figure 6 A top view of a cone-shaped main body provided in an embodiment of the present invention;

[0035] Figure 7 This is a schematic diagram of the structure of an LED epitaxial wafer provided in an embodiment of the present invention;

[0036] Figure 8 This is a schematic flowchart illustrating a method for fabricating a composite patterned substrate according to an embodiment of the present invention.

[0037] Figure 9 for Figure 8 A schematic diagram of the fabrication process of a corresponding composite patterned substrate;

[0038] Figure 10 This is a schematic diagram of the structure of a first photoresist pillar provided in an embodiment of the present invention;

[0039] Figure 11 This is a schematic diagram of the arrangement of first photoresist pillars on a flat substrate according to an embodiment of the present invention;

[0040] Figure 12 This is a schematic flowchart of another method for preparing a composite patterned substrate according to an embodiment of the present invention;

[0041] Figure 13 for Figure 12 A schematic diagram of the fabrication process for a corresponding composite patterned substrate. Detailed Implementation

[0042] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and not intended to limit it. Furthermore, it should be noted that, for ease of description, the accompanying drawings show only the parts relevant to the present invention, and not all of the structures.

[0043] The terminology used in the embodiments of this invention is for the purpose of describing specific embodiments only and is not intended to limit the invention. It should be noted that directional terms such as "upper," "lower," "left," and "right" described in the embodiments of this invention are used to describe the angles shown in the accompanying drawings and should not be construed as limiting the embodiments of this invention. Furthermore, in the context, it should be understood that when referring to an element being formed "on" or "below" another element, it can be formed not only directly on or below the other element, but also indirectly on or below it through intermediate elements. The terms "first," "second," etc., are used for descriptive purposes only and do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0044] The term "comprising" and its variations as used in this invention are open-ended, meaning "including but not limited to". The term "based on" means "at least partially based on". The term "one embodiment" means "at least one embodiment".

[0045] It should be noted that the concepts of "first" and "second" mentioned in this invention are only used to distinguish the corresponding contents and are not used to limit the order or interdependence.

[0046] It should be noted that the terms "a" and "a plurality of" used in this invention are illustrative rather than restrictive. Those skilled in the art should understand that, unless otherwise expressly indicated in the context, they should be understood as "one or more".

[0047] Figure 1 This is a side view of a composite patterned substrate provided in an embodiment of the present invention. Figure 2 This is a top view of a composite patterned substrate provided in an embodiment of the present invention. Figure 3 This is a schematic diagram of a cone-shaped main body provided in an embodiment of the present invention. Figure 4 A top view of a cone-shaped main body with hexagonal arrangement provided in an embodiment of the present invention. Figure 5 This is a schematic diagram of a conical structure provided in an embodiment of the present invention, as shown below. Figures 1 to 5 As shown, the composite patterned substrate includes a substrate 10 and a plurality of conical structures 20 located on one side surface of the substrate 10; the plurality of conical structures 20 are arranged in a hexagonal pattern; each conical structure 20 includes a conical main body 21 and a filling portion 22. The conical main body 21 includes a vertex 211, a conical surface 212 and a bottom surface 213. The conical surface 212 has six first arc-shaped grooves 2121 and six first arc-shaped protrusions 2122. The first arc-shaped grooves 2121 are respectively located on the conical surface 212, aligned with the six adjacent conical structures 20, and are spaced apart from the first arc-shaped protrusions 2122. Both the first arc-shaped grooves 2121 and the first arc-shaped protrusions 2122 extend from the vertex 211 to the bottom surface 213. The filling portion 22 fills the first arc-shaped grooves 2121.

[0048] Specifically, such as Figure 1 and Figure 2 As shown, the composite patterned substrate includes a substrate 10 and multiple conical structures 20 located on one side surface of the substrate 10. The multiple conical structures 20 are arranged in a hexagonal pattern, which can effectively reduce the gaps between the multiple conical structures 20 and improve space utilization. (Reference) Figure 2 When multiple conical structures 20 are arranged in a hexagonal pattern, along the diagonal direction of the hexagon, that is... Figure 2 In the x1, x2, and x3 directions shown, there is a smaller gap between adjacent conical structures 20, therefore the x1, x2, and x3 directions are the close-packed directions of the composite patterned substrate, while the other directions have relatively larger gaps, which are the sparse-packed directions of the composite patterned substrate. For example, the substrate 10 can be a sapphire substrate.

[0049] Furthermore, since the etching rate of the plasma is inconsistent in the close-packed and sparse-packed directions when forming multiple conical structures 20 on the surface of the substrate 10 using an etching process, the C-plane flatness of the formed multiple conical structures 20 may be uneven in the close-packed and sparse-packed directions. Therefore, when preparing the conical structure 20, the conical structure 20 includes a conical main body 21 and a filling part 22. Figure 3 and Figure 4As shown, the conical main body 21 includes a vertex 211, a conical surface 212, and a bottom surface 213. The conical surface 212 has six first arc-shaped grooves 2121 and six first arc-shaped protrusions 2122. The first arc-shaped grooves 2121 are respectively located on the conical surface 212 aligned with the six adjacent conical structures 20, and are spaced apart from the first arc-shaped protrusions 2122. Both the first arc-shaped grooves 2121 and the first arc-shaped protrusions 2122 extend from the vertex 211 to the bottom surface 213.

[0050] Specifically, in order to increase the gap between adjacent conical structures 20 in the close-packed direction, refer to Figure 4 When preparing the conical main body 21, the conical surface 212 of the conical main body 21 has six first arc-shaped grooves 2121 in the close-packed direction and six first arc-shaped protrusions 2122 in the sparse-packed direction. The first arc-shaped grooves 2121 and the first arc-shaped protrusions 2122 are spaced apart, and the first arc-shaped grooves 2121 of adjacent conical main bodies 21 are arranged opposite to each other. This can effectively increase the gap of the conical structure 20 in the close-packed direction, thereby reducing the difference in plasma concentration and etching rate between the close-packed and sparse-packed directions during etching, thereby improving the C-surface flatness of the composite patterned substrate. At the same time, the first arc-shaped grooves 2121 in the conical main body 21 increase the surface area of ​​the composite patterned substrate.

[0051] Further, refer to Figure 3 and Figure 5 The filling portion 22 fills the first arc-shaped groove 2121, forming a complete conical structure 20. Exemplarily, the filling portion 22 can be a heterogeneous material. The heterogeneous material is longitudinally filled in the first arc-shaped groove 2121, extending from the apex 211 of the conical main body 21 to the bottom surface 213. Therefore, this composite patterned substrate is more conducive to epitaxial growth and improves light extraction efficiency. In an optional embodiment, such as... Figure 2 As shown, the center-to-center distance d between the bottom surfaces of any two adjacent conical structures 20 is 1μm-8μm.

[0052] This invention improves space utilization by forming multiple hexagonally arranged conical structures on the substrate surface. In the close-packed direction of the hexagonal arrangement, the conical main body of each structure is configured as a first arc-shaped groove, while in the sparse-packed direction, it is configured as a first arc-shaped protrusion. This effectively reduces the gap difference between adjacent conical structures in the close-packed and sparse-packed directions, thereby reducing the etching rate difference between the close-packed and sparse-packed directions during etching. This effectively improves the C-plane flatness of the composite patterned substrate, which is beneficial for epitaxial crystal growth and improves crystal quality. Simultaneously, the first arc-shaped groove structure effectively increases the surface area of ​​the composite patterned substrate. Furthermore, the filling portion formed at the first arc-shaped groove position of the conical main body effectively reduces the probability of dislocation generation during epitaxial growth, optimizes the stress distribution of the epitaxial layer, and improves light extraction efficiency.

[0053] Optionally, Figure 6 A top view of a cone-shaped main body provided in an embodiment of the present invention, such as... Figure 6 As shown, the minimum length of the projection of the first arc-shaped groove 2121 onto the bottom surface 213 in the radial direction of the bottom surface 213 is L, and the maximum length of the bottom surface 213 in the radial direction is R, where 0 < L: R / 2 ≤ 0.8.

[0054] Specifically, the gap between two adjacent conical main bodies 21 in the close-packing direction can be changed by adjusting the indentation depth of the first arc-shaped groove 2121 on the conical main body 21. (Reference) Figure 6 The minimum length of the projection of the first arc-shaped groove 2121 onto the bottom surface 213 in the radial direction is L, and the maximum length of the bottom surface 213 in the radial direction is R, where 0 < L:R / 2 ≤ 0.8. When L:R / 2 = 0.8, the first arc-shaped groove 2121 has the minimum concave depth, and the gap between two adjacent conical main bodies 21 in the close-packing direction is also the minimum. When L is close to 0, the first arc-shaped groove 2121 has the maximum concave depth, and the gap between two adjacent conical main bodies 21 in the close-packing direction is also the maximum. Therefore, the concave depth of the first arc-shaped groove 2121 in the close-packing direction can be adjusted according to the gap between two adjacent conical main bodies 21 in the sparse-packing direction, so that the difference in etching rate between the close-packing and sparse-packing directions is minimized during the etching process of the conical main bodies 21, thus obtaining the optimal C-surface flatness.

[0055] Optionally, Figure 7 This is a schematic diagram of the structure of an LED epitaxial wafer provided in an embodiment of the present invention, as shown below. Figure 7 As shown, the LED epitaxial wafer includes any of the composite patterned substrates provided in this embodiment of the invention, and an epitaxial layer 30 formed on the composite patterned substrate. When the composite patterned substrate has good C-plane flatness, the epitaxial layer 30 formed on its surface will also have good flatness. At the same time, since the composite patterned substrate includes a filling portion 22, the probability of dislocation generation during the growth of the epitaxial layer 30 is effectively reduced.

[0056] Optionally, Figure 8 This is a schematic flowchart illustrating a method for fabricating a composite patterned substrate according to an embodiment of the present invention. Figure 9 for Figure 8 A schematic diagram of the fabrication process for a corresponding composite patterned substrate is provided. This fabrication method is used to prepare any of the composite patterned substrates provided in the above embodiments, such as... Figure 8 As shown, the preparation method includes:

[0057] S101, Provides a flat substrate.

[0058] Specifically, refer to Figure 9 In step A1, a flat substrate 40 is provided for fabricating a composite patterned substrate. Exemplarily, the flat substrate 40 can be a clean sapphire substrate.

[0059] S102. Form the first photoresist layer on the flat substrate.

[0060] Specifically, refer to Figure 9 In step B1, a first photoresist layer 50 is formed on the flat substrate 40. Exemplarily, the first photoresist layer 50 can be prepared by spin coating, and the first photoresist layer 50 can be a positive photoresist or a negative photoresist.

[0061] S103. Expose and develop the first photoresist layer to obtain multiple first photoresist pillars.

[0062] Specifically, refer to Figure 9 In step C1, the first photoresist layer 50 is exposed and developed to obtain multiple first photoresist pillars 51. Figure 10 This is a schematic diagram of the structure of a first photoresist pillar provided in an embodiment of the present invention. Figure 11 This is a schematic diagram illustrating the arrangement of first photoresist pillars on a flat substrate according to an embodiment of the present invention, as shown below. Figure 10 and Figure 11 As shown, a plurality of first photoresist pillars 51 are arranged in a hexagonal pattern, and the sides of the first photoresist pillars 51 have a plurality of second arc-shaped grooves 511, which are perpendicular to the surface of the flat substrate 40. In an optional embodiment, the height of the first photoresist pillars 51 is 1 μm - 3.8 μm. (Reference) Figure 11 Multiple second arc-shaped grooves 511 are located in the close-packed direction of multiple first photoresist pillars 51, that is... Figure 11 In the x1, x2 and x3 directions shown, the center-to-center distance d between the bottom surfaces of two adjacent first photoresist pillars 51 can be 1μm-8μm.

[0063] Further, in an optional embodiment, when the first photoresist layer 50 is processed by exposure and development to obtain a plurality of first photoresist pillars 51, the projection of the second arc-shaped groove 511 of the first photoresist pillar 51 in the height direction is any one of an arc, a triangle, or a polygon. For example, refer to... Figure 10 and Figure 11The center-to-center distance between two adjacent first photoresist pillars 51 can be 3.5 μm, and the height can be 2.5 μm. The maximum length of the first photoresist pillar 51 in the radial direction of its projection onto the bottom surface can be 2.3 μm, and the indentation depth of the second arc-shaped groove 511 in the radial direction of its projection onto the bottom surface can be 0.6 μm. Furthermore, nanoimprint lithography can also be used to process the first photoresist layer 50 to form the first photoresist pillars 51.

[0064] S104. Using the first photoresist pillar as a mask, and employing an etching process and first etching conditions, the first photoresist pillar and the flat substrate are etched to form the substrate and multiple cone-shaped main bodies located on one side of the substrate.

[0065] Specifically, refer to Figure 9 In step D1, using the first photoresist pillar 51 as a mask, an etching process is employed under the first etching conditions to etch the first photoresist pillar 51 and the flat substrate 40. Part of the flat substrate 40 is etched to form multiple cone-shaped main bodies 21, while the remaining unetched portion of the flat substrate 40 forms the substrate 10. (Referring to...) Figure 3 and Figure 4 The conical main body 21 includes a vertex 211, a conical surface 212 and a bottom surface 213. The conical surface 212 has six first arc-shaped grooves 2121 and six first arc-shaped protrusions 2122. The first arc-shaped grooves 2121 are respectively located on the conical surface 212, which are aligned with the six adjacent conical main bodies 21, and are spaced apart from the first arc-shaped protrusions 2122. The first arc-shaped grooves 2121 and the first arc-shaped protrusions 2122 both extend from the vertex 211 to the bottom surface 213.

[0066] Specifically, since the first photoresist pillar 51 is used as a mask during the etching process, each cone-shaped main body 21 corresponds one-to-one with the first photoresist pillar 51. When the first photoresist pillar 51 is arranged in a hexagonal pattern, the multiple cone-shaped main bodies 21 are also arranged in a hexagonal pattern on one side of the substrate 10. This arrangement effectively improves space utilization. In addition, when the multiple second arc-shaped grooves 511 of the first photoresist pillar 51 are located in the close-packed direction of the hexagonal arrangement, the gap difference between adjacent first photoresist pillars 51 in the close-packed and sparse-packed directions is not significant. Therefore, the difference in etching rate between the close-packed and sparse-packed directions during the etching process can be effectively reduced. Consequently, when forming multiple cone-shaped main bodies 21, the cone-shaped main bodies 21 form a first arc-shaped groove 2121 in the close-packed direction of the hexagonal arrangement and a first arc-shaped protrusion 2122 in the sparse-packed direction, effectively improving the flatness of the C-surface of the cone-shaped main body 21 and the substrate 10.

[0067] In an optional embodiment, the etching process includes inductively coupled plasma dry etching, and the first etching conditions include an etching process pressure of 2.5 mTor, an upper RF electrode power of 1400 W, a lower RF electrode power of 400 W-750 W, a boron trichloride gas flow rate of 100 sccm, a CHF3 flow rate of 10-20 sccm, a He pressure of 4-6 Tor, and a cooler temperature of 10-25 °C.

[0068] Further, refer to Figure 6 Adjusting the etching parameters can change the height of the conical main body 21, as well as the minimum length L and the maximum length R of the bottom surface 213 in the radial direction of the projection pattern of the first arc groove 2121 on the bottom surface 213, so that the variation range of L is 0 < L: R / 2 ≤ 0.8.

[0069] Furthermore, after etching the first photoresist pillar 51 and the flat substrate 40 to form the substrate 10 and a plurality of cone-shaped main bodies 21 located on one side surface of the substrate 10, the substrate 10 and the plurality of cone-shaped main bodies 21 can be cleaned to remove residual byproducts and photoresist from the etching process. For example, the substrate 10 and the plurality of cone-shaped main bodies 21 can be immersed in a mixed solution of concentrated sulfuric acid and hydrogen peroxide for cleaning, wherein the volume ratio of concentrated sulfuric acid to hydrogen peroxide is 5:1, the temperature of the mixed solution is controlled at 130°C, and the cleaning time is 25 minutes.

[0070] S105. Fill the first arc-shaped groove of the cone-shaped main body with a heterogeneous material to obtain a filling part, so as to form a cone structure with the cone-shaped main body.

[0071] Specifically, refer to Figure 9 In step E1, a heterogeneous material is filled into the first arc-shaped groove 2121 of the cleaned cone-shaped main body 21 to obtain a filling part 22, which together with the cone-shaped main body 21 forms a cone structure 20. (See reference) Figure 3 and Figure 5 The heterogeneous material is longitudinally filled from the cone apex 211 of the cone-shaped main body 21 to the bottom surface 213. For example, the heterogeneous material can be silicon oxide.

[0072] Further reference Figure 9 In step E1, after filling the first arc-shaped groove 2121 with heterogeneous material, a complete composite patterned substrate is obtained. The composite patterned substrate includes a substrate 10 and a hexagonally arranged conical structure 20 located on one side surface of the substrate. The conical structure 20 has a longitudinally filled heterogeneous material, which can effectively reduce the probability of dislocation generation during epitaxial growth using the composite patterned substrate, while improving the light extraction efficiency.

[0073] This invention utilizes a first photoresist pillar as a mask to etch a flat substrate, forming the substrate and a hexagonal conical structure located on one side of the substrate. The conical main body of the conical structure features a first arc-shaped groove in the close-packed direction of the hexagonal arrangement and a first arc-shaped protrusion in the sparse-packed direction. This effectively reduces the gap difference between adjacent conical structures in the close-packed and sparse-packed directions, thereby reducing the etching rate difference between the close-packed and sparse-packed directions during etching. This effectively improves the C-plane flatness of the composite patterned substrate, which is beneficial for epitaxial crystal growth and improves crystal quality. Furthermore, filling the first arc-shaped groove of the conical main body with a heterogeneous material to form a filling portion effectively reduces the probability of dislocation generation during epitaxial growth, optimizes the stress distribution of the epitaxial layer, and improves light extraction efficiency.

[0074] Optionally, Figure 12 This is a schematic flowchart of another method for fabricating a composite patterned substrate according to an embodiment of the present invention. Figure 13 for Figure 12 A schematic diagram of the fabrication process of a corresponding composite patterned substrate is shown. This embodiment is a refinement of the above embodiment. Specifically, for the step of filling the first arc-shaped groove of the cone-shaped main body with a heterogeneous material to obtain a filled portion, which forms a conical structure with the cone-shaped main body, it can be further refined as follows:

[0075] A heterogeneous material is deposited on the side of the conical body away from the substrate, the heterogeneous material fills the first arc-shaped groove and forms a heterogeneous material layer on the side of the conical body away from the substrate;

[0076] A second photoresist layer is formed on the side of the heteromaterial layer facing away from the substrate;

[0077] The second photoresist layer is exposed and developed to obtain multiple second photoresist pillars; wherein, the second photoresist pillars are cylindrical, and in the thickness direction of the substrate, the center projection of the second photoresist pillars coincides with that of the conical main body.

[0078] Using the second photoresist pillar as a mask, the second photoresist pillar and the heteromaterial layer are etched using an etching process and second etching conditions to obtain a filling portion, which together with the cone-shaped main body forms a cone structure.

[0079] For parts not described in detail in this embodiment, please refer to the foregoing embodiments. For example... Figure 12 As shown, the preparation method includes:

[0080] S201, Provides a flat substrate.

[0081] S202, Form the first photoresist layer on the flat substrate.

[0082] S203. Expose and develop the first photoresist layer to obtain multiple first photoresist pillars.

[0083] S204. Using the first photoresist pillar as a mask, and employing an etching process and first etching conditions, the first photoresist pillar and the flat substrate are etched to form the substrate and multiple cone-shaped main bodies located on one side of the substrate.

[0084] S205. A heterogeneous material is deposited on the side of the conical main body away from the substrate. The heterogeneous material fills the first arc-shaped groove and forms a heterogeneous material layer on the side of the conical main body away from the substrate.

[0085] Specifically, refer to Figure 13 In step E2, a heterogeneous material is deposited over the substrate 10 and the conical body portion 21. The heterogeneous material completely covers the conical body portion 21 and fills the first arc-shaped groove 2121, and a heterogeneous material layer 60 is formed on the side of the conical body portion 21 facing away from the substrate 10. For example, the heterogeneous material can be silicon oxide.

[0086] In an optional embodiment, plasma-enhanced chemical vapor deposition (PECVD) can be used to deposit a heterogeneous material on the side of the conical body 21 facing away from the substrate 10, under the following process conditions: SiH4 flow rate range of 150-300 sccm, N2O flow rate range of 1500-5000 sccm, N2 flow rate range of 2000-3500 sccm, reaction chamber temperature of 250-350°C, and RF power of 150-350 W. Exemplarily, the thickness of the heterogeneous material layer 60 can be 2.6 μm. Furthermore, other physical and chemical deposition processes can also be used when depositing the heterogeneous material; this embodiment of the invention does not limit the specific methods used.

[0087] S206. A second photoresist layer is formed on the side of the heteromaterial layer away from the substrate.

[0088] Specifically, refer to Figure 13 In step F2, a second photoresist layer 70 can be formed on the side of the heteromaterial layer 60 facing away from the substrate 10 using a spin-coating process. Exemplarily, the second photoresist layer 70 can be a positive photoresist or a negative photoresist.

[0089] S207. Expose and develop the second photoresist layer to obtain multiple second photoresist pillars.

[0090] Specifically, refer to Figure 13 In step G2, the second photoresist layer 70 is exposed and developed to obtain a plurality of second photoresist pillars 701, wherein the second photoresist pillars 701 are cylindrical and their center projections coincide with those of the conical main body portion 21 in the thickness direction of the substrate 10. For example, the thickness of the second photoresist pillars 701 can be 2.1 μm, and the center-to-center distance between two adjacent second photoresist pillars 701 can be 3.5 μm.

[0091] S208. Using the second photoresist pillar as a mask, and employing an etching process and second etching conditions, the second photoresist pillar and the heteromaterial layer are etched to obtain a filling portion, which together with the cone-shaped main body forms a cone structure.

[0092] Specifically, refer to Figure 13 In step H2, the second photoresist pillar 701 is used as a mask, and the second photoresist pillar 701 and the heteromaterial layer 60 are etched using an etching process, leaving only the heteromaterial located in the first arc-shaped groove 2121, to obtain the filling part 22, which together with the cone-shaped main body 21 forms a cone structure.

[0093] In an optional embodiment, the etching process includes inductively coupled plasma dry etching. The second etching conditions include an etching process pressure of 2.5 mTor, an upper RF electrode power of 1400 W, a lower RF electrode power of 400 W-750 W, a boron trichloride gas flow rate of 100 sccm, a CHF3 flow rate of 10-20 sccm, a He pressure of 4-6 Tor, and a cooler temperature of 10-25°C. Further, the etching process can also employ a combination of dry and wet etching; this embodiment of the invention does not limit the specific method used.

[0094] Furthermore, after etching is completed, residual etching byproducts and photoresist may remain on the composite patterned substrate, including the substrate 10 and the conical structure 20 located on one side surface of the substrate 10. Therefore, it can be cleaned to obtain a clean composite patterned substrate. For example, the substrate 10 and the conical structure 20 located on one side surface of the substrate 10 can be immersed in a mixed solution of concentrated sulfuric acid and hydrogen peroxide for cleaning, wherein the volume ratio of concentrated sulfuric acid to hydrogen peroxide is 5:1, the temperature of the mixed solution is controlled at 130°C, and the cleaning time is 25 minutes.

[0095] This invention provides an embodiment of the invention that deposits a heterogeneous material on a substrate and multiple conical main bodies located on one side of the substrate to form a heterogeneous material layer. Then, using a second photoresist pillar as a mask, the heterogeneous material layer is etched. This ensures that the heterogeneous material can completely fill the first arc-shaped groove and extend longitudinally from the apex of the conical main body to the bottom surface. This effectively reduces the probability of dislocation generation during epitaxial growth using the composite patterned substrate and improves the light extraction efficiency.

[0096] Note that the above description is merely a preferred embodiment of the present invention and the technical principles employed. Those skilled in the art will understand that the present invention is not limited to the specific embodiments described herein, and various obvious changes, readjustments, combinations, and substitutions can be made without departing from the scope of protection of the present invention. Therefore, although the present invention has been described in detail through the above embodiments, the present invention is not limited to the above embodiments, and may include many other equivalent embodiments without departing from the concept of the present invention, the scope of which is determined by the scope of the appended claims.

Claims

1. A composite patterned substrate, characterized in that, include: A substrate and a plurality of conical structures located on one side surface of the substrate; the plurality of conical structures are arranged in a hexagonal pattern; The conical structure includes a conical main body and a filling part. The conical main body includes a vertex, a conical surface, and a bottom surface. The conical surface has six first arc-shaped grooves and six first arc-shaped protrusions. The first arc-shaped grooves are respectively located at positions of the six adjacent conical structures aligned with the conical surface and are spaced apart from the first arc-shaped protrusions. Both the first arc-shaped grooves and the first arc-shaped protrusions extend from the vertex to the bottom surface. The filling portion fills the first arc-shaped groove.

2. The composite patterned substrate according to claim 1, characterized in that, The minimum length of the projection of the first arc-shaped groove onto the bottom surface in the radial direction of the bottom surface is L, and the maximum length of the bottom surface in the radial direction is R, where 0 < L: R / 2 ≤ 0.

8.

3. The composite patterned substrate according to claim 1, characterized in that, The center-to-center distance between the bottom surfaces of any two adjacent conical structures is 1 μm to 8 μm.

4. An LED epitaxial wafer, characterized in that, It includes the composite patterned substrate as described in any one of claims 1-3, and the epitaxial layer formed on the composite patterned substrate.

5. A method for preparing a composite patterned substrate, characterized in that, The method for preparing the composite patterned substrate as described in any one of claims 1-3 includes: Provide flat substrates; A first photoresist layer is formed on the flat substrate; The first photoresist layer is exposed and developed to obtain a plurality of first photoresist pillars; wherein the plurality of first photoresist pillars are arranged in a hexagonal shape, and the side of the first photoresist pillars has a plurality of second arc-shaped grooves, the second arc-shaped grooves being perpendicular to the surface of the flat substrate. Using the first photoresist pillar as a mask, an etching process is employed under first etching conditions to etch the first photoresist pillar and the flat substrate, forming a substrate and a plurality of conical main bodies located on one side surface of the substrate; wherein, the plurality of conical main bodies are arranged in a hexagonal pattern; each conical main body includes a vertex, a conical surface, and a bottom surface, the conical surface having six first arc-shaped grooves and six first arc-shaped protrusions; the first arc-shaped grooves are respectively located at positions aligning with the six adjacent conical main bodies on the conical surface, and are spaced apart from the first arc-shaped protrusions; both the first arc-shaped grooves and the first arc-shaped protrusions extend from the vertex to the bottom surface; A heterogeneous material is filled into the first arc-shaped groove of the cone-shaped main body to obtain a filled portion, which together with the cone-shaped main body forms a conical structure.

6. The preparation method according to claim 5, characterized in that, The height of the first photoresist pillar is 1μm - 3.8μm.

7. The preparation method according to claim 5, characterized in that, The projection of the second arc-shaped groove of the first photoresist pillar in the height direction can be any one of a circular arc, a triangle, or a polygon.

8. The preparation method according to claim 5, characterized in that, A heterogeneous material is filled into the first arc-shaped groove of the conical main body to obtain a filled portion, which forms a conical structure with the conical main body, including: The heteromaterial is deposited on the side of the conical body portion away from the substrate, the heteromaterial filling the first arc-shaped groove and forming a heteromaterial layer on the side of the conical body portion away from the substrate; A second photoresist layer is formed on the side of the heteromaterial layer facing away from the substrate; The second photoresist layer is exposed and developed to obtain a plurality of second photoresist pillars; wherein the second photoresist pillars are cylindrical, and in the thickness direction of the substrate, the second photoresist pillars coincide with the center projection of the conical main body; Using the second photoresist pillar as a mask, the second photoresist pillar and the heteromaterial layer are etched using an etching process and a second etching condition to obtain the filling portion, which together with the cone-shaped main body portion forms a cone structure.

9. The preparation method according to claim 8, characterized in that, The etching process includes inductively coupled plasma dry etching. In the first and second etching conditions, the etching process pressure is 2.5 mTor, the upper RF electrode power is 1400 W, the lower RF electrode power is 400 W-750 W, the boron trichloride gas flow rate is 100 sccm, the CHF3 flow rate is 10-20 sccm, the He pressure is 4-6 Tor, and the cooler temperature is 10-25℃.

10. The preparation method according to claim 8, characterized in that, A heterogeneous material is deposited on the side of the conical body facing away from the substrate, including: The heteromaterial was deposited on the side of the conical body away from the substrate using plasma-enhanced chemical vapor deposition (PECVD) with SiH4 flow rate of 150-300 sccm, N2O flow rate of 1500-5000 sccm, N2 flow rate of 2000-3500 sccm, reaction chamber temperature of 250-350°C, and RF power of 150-350 W.

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