A patterned substrate, preparation method and LED epitaxial wafer

Abstract

An embodiment of the present invention discloses a patterned substrate, a preparation method, and an LED epitaxial wafer. The preparation method includes providing a sapphire substrate; depositing a first heterogeneous material on the substrate to form a porous heterogeneous layer with a preset porosity, or mixedly depositing at least two heterogeneous materials to form a composite heterogeneous layer with a preset doping ratio; patterning the composite heterogeneous layer or the porous heterogeneous layer through an etching process to form a plurality of first heterogeneous microstructures with a preset surface roughness. The plurality of first heterogeneous microstructures with rough surfaces can promote the closing of dislocations within the epitaxial layer along the sides and at the top of the pattern, thereby improving the crystal quality of the epitaxial material and reducing the stress influence on the substrate surface. At the same time, the patterned substrate can ensure the improvement of the light path. The large refractive difference between the substrate and the heterogeneous material can also improve the light extraction efficiency.

Description

Technical Field

[0001] The embodiments of the present invention relate to the field of optoelectronic technology, in particular to the field of light-emitting device technology, and specifically to a patterned substrate, a preparation method, and an LED epitaxial wafer. Background Art

[0002] Group III nitride semiconductors, with gallium nitride (GaN) being a research hotspot, possess excellent optoelectronic properties and a wide, tunable bandgap. They excel in applications such as light-emitting diodes (LEDs), lasers, photodetectors, and high-power transistors. Nitride semiconductors are commonly grown using epitaxial growth methods.

[0003] In the traditional epitaxial growth process, the lattice mismatch and thermal mismatch between the epitaxial layer and the substrate will cause cracks in the film, resulting in poor quality of the epitaxial film and limiting its growth. To improve this problem, the current approach is to introduce low-refractive-index heterogeneous materials to prepare patterned composite substrates. Patterned substrates are currently the main substrate material used for the epitaxial growth of GaN LEDs. The microstructure and optical parameters of their surface patterns have a significant impact on the quality of the epitaxial wafer. Since different materials have their own intrinsic refractive index levels, the light extraction efficiency can be improved by lowering the material's refractive index. However, the surface microstructure and optical parameters have a significant impact on the light extraction efficiency of the epitaxial wafer, making it difficult to meet industry and market demands. Summary of the Invention

[0004] The present invention discloses a patterned substrate, a preparation method and an LED epitaxial wafer. A porous heterogeneous layer or a composite heterogeneous layer with a preset porosity is deposited on a sapphire substrate using a deposition technique, and the effect of roughening a specific fine surface is achieved by using a difference in etching rate to improve light extraction efficiency.

[0005] In a first aspect, an embodiment of the present invention provides a method for preparing a patterned substrate, comprising:

[0006] Providing a sapphire substrate;

[0007] A first heterogeneous material is deposited on a sapphire substrate to form a porous heterogeneous layer with a preset porosity; at least two heterogeneous materials are mixed and deposited on the sapphire substrate to form a composite heterogeneous layer, wherein the at least two heterogeneous materials include a second heterogeneous material and a third heterogeneous material, and the second heterogeneous material and the third heterogeneous material have different etching rates.

[0008] The composite heterogeneous layer or the heterogeneous layer with pores is patterned through an etching process to form a plurality of first heterogeneous microstructures with a preset surface roughness.

[0009] Among them, the first heterogeneous material is a first layer material deposited on a sapphire substrate, including but not limited to SiO2; at least two materials are deposited in the composite heterogeneous layer, the second heterogeneous material refers to the main material in the composite heterogeneous layer, and the third heterogeneous material refers to other auxiliary materials in the composite heterogeneous layer.

[0010] Optionally, depositing a first heterogeneous material on the sapphire substrate to form a porous heterogeneous layer with a preset porosity includes depositing the first heterogeneous material to form the porous heterogeneous layer with a preset porosity in a low-temperature environment, wherein the temperature of the low-temperature environment is lower than 100° C.;

[0011] Optionally, patterning the composite heterogeneous layer or the porous heterogeneous layer by an etching process to form a plurality of first heterogeneous microstructures with a preset surface roughness specifically includes:

[0012] The first heterogeneous microstructure is a mask, and the sapphire substrate is patterned by an etching process to form a plurality of sapphire microstructures with a preset surface roughness on the surface of the sapphire substrate;

[0013] Optionally, after patterning the composite heterogeneous layer or the porous heterogeneous layer by an etching process to form a plurality of first heterogeneous microstructures with a preset surface roughness, the method specifically includes:

[0014] depositing a first heterogeneous material on the surface of the first heterogeneous microstructure in a high-temperature environment to form a covering heterogeneous layer, wherein the temperature of the high-temperature environment is higher than 100° C.;

[0015] Patterning the covering heterogeneous layer using an etching process to form a plurality of second heterogeneous microstructures, wherein the second heterogeneous microstructures include the first heterogeneous microstructure and the covering heterogeneous layer covering the first heterogeneous microstructure;

[0016] Optionally, after depositing a first heterogeneous material on a sapphire substrate to form a porous heterogeneous layer with a preset porosity, the method specifically includes:

[0017] Performing surface modification on the porous heterogeneous layer to make the porous heterogeneous layer hydrophobic;

[0018] Optionally, at least two heterogeneous materials are mixed and deposited on a sapphire substrate to form a composite heterogeneous layer with a preset doping ratio, including:

[0019] Adopting an ion-assisted electron beam dual-source co-evaporation process, the second heterogeneous material and the third heterogeneous material are mixed and deposited according to at least one of a preset evaporation electron beam power, a preset vacuum pressure, and a preset auxiliary radio frequency source power;

[0020] Optionally, at least two heterogeneous materials are mixed and deposited on a sapphire substrate to form a composite heterogeneous layer with a preset doping ratio, including:

[0021] Using a plasma enhanced chemical vapor deposition process, the second heterogeneous material and the third heterogeneous material are mixed and deposited in a preset gas source ratio;

[0022] Optionally, at least two heterogeneous materials are mixed and deposited on the sapphire substrate to form a composite heterogeneous layer, comprising:

[0023] Using a plasma enhanced chemical vapor deposition process, alternately depositing a second heterogeneous material and a third heterogeneous material at a preset deposition time;

[0024] Optionally, after depositing a first heterogeneous material on a sapphire substrate to form a porous heterogeneous layer with a preset porosity; or after depositing at least two heterogeneous materials on a sapphire substrate to form a composite heterogeneous layer with a preset doping ratio, the method further includes:

[0025] The porous heterogeneous layer or composite heterogeneous layer is heat treated under the conditions of a temperature of 300 to 850° C. and a time of 5 to 20 minutes.

[0026] Optionally, the first heterogeneous material and the second heterogeneous material both include silicon dioxide, silicon nitride or silicon; the third heterogeneous material includes aluminum oxide, aluminum nitride and silicon dioxide;

[0027] The refractive index of the third heterogeneous material is smaller than the refractive index of the second heterogeneous material.

[0028] In a second aspect, an embodiment of the present invention further provides a patterned substrate, which is prepared using the patterned substrate preparation method as described in any one of the first aspects.

[0029] In a third aspect, an embodiment of the present invention further provides an LED epitaxial wafer, comprising the patterned substrate according to the second aspect.

[0030] In the technical solution of the embodiment of the present invention, a sapphire substrate is provided; a first heterogeneous material is deposited on the sapphire substrate to form a porous heterogeneous layer with a preset porosity; or, at least two heterogeneous materials with different etching rates are mixed and deposited on the sapphire substrate to form a composite heterogeneous layer; the composite heterogeneous layer with a preset doping ratio or the porous heterogeneous layer with a preset porosity is patterned through an etching process to form a plurality of first heterogeneous microstructures with a preset surface roughness, thereby changing the roughness of the surface of the heterogeneous layer and the optical path, and improving the light extraction efficiency by reducing the refractive index of the heterogeneous layer; and the substrate bonding is improved by patterning the substrate, thereby facilitating the preparation of substrates with different structures.

[0031] The contents described in this section are not intended to identify the key or important features of the embodiments of the present invention, nor are they intended to limit the scope of the present invention. Other features of the present invention will become readily understood through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] To more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. A person skilled in the art can also derive other drawings based on these drawings without inventive effort, and they do not constitute a limitation of the present invention. Among them:

[0033] Figure 1 This is a flow chart of a method for preparing a patterned substrate provided by an embodiment of the present invention;

[0034] Figure 2 yes Figure 1 A structural flow chart of a method for preparing a patterned substrate is shown;

[0035] Figure 3 is a flow chart of another method for preparing a patterned substrate provided by an embodiment of the present invention;

[0036] Figure 4 yes Figure 3 A structural flow chart of a method for preparing a patterned substrate is shown;

[0037] Figure 5 This is a flow chart of another method for preparing a patterned substrate provided by an embodiment of the present invention;

[0038] Figure 6 yes Figure 5 A structural flow chart of a method for preparing a patterned substrate is shown;

[0039] Figure 7 This is an AFM test image of a patterned substrate prepared using prior art;

[0040] Figure 8 This is an AFM test image of the patterned substrate prepared in the first specific embodiment of the present invention;

[0041] Figure 9 This is an AFM test image of the patterned substrate prepared in the second specific embodiment of the present invention;

[0042] Figure 10 1 is a schematic structural diagram of a patterned substrate provided by an embodiment of the present invention;

[0043] Figure 11 It is a structural schematic diagram of an LED epitaxial wafer provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0044] The present invention will be further described in detail below with reference to the accompanying drawings and examples. It will be understood that the specific embodiments described herein are intended only to illustrate the present invention and are not intended to limit the present invention. It should also be noted that, for ease of description, the accompanying drawings only illustrate portions relevant to the present invention, not all structures.

[0045] Figure 1 is a flow chart of a method for preparing a patterned substrate provided by an embodiment of the present invention. Figure 2 yes Figure 1 The structural flow chart of the method for preparing the patterned substrate is shown below. Figure 1 and Figure 2 The method for preparing a patterned substrate provided in an embodiment of the present invention is described. The method can be used to prepare a patterned substrate, and the method specifically includes:

[0046] S110, providing a sapphire substrate.

[0047] Among them, such as Figure 2 As shown in FIG. a), the sapphire substrate 10 can be a sapphire flat substrate. The size can be selected as needed and is not limited here. Optionally, the sapphire substrate 10 needs to be cleaned before use. Cleaning methods can include conventional chemical cleaning and plasma cleaning. Conventional chemical cleaning uses chemical reagents to remove impurities and stains on the sapphire flat substrate. Plasma cleaning utilizes the properties of active components in plasma to treat the sample surface to improve the surface crystalline quality of the sapphire flat substrate.

[0048] S120. Depositing a first heterogeneous material on a sapphire substrate to form a porous heterogeneous layer with a preset porosity; or, depositing at least two heterogeneous materials on a sapphire substrate to form a composite heterogeneous layer with a preset doping ratio, wherein the at least two heterogeneous materials include a second heterogeneous material and a third heterogeneous material, and the second heterogeneous material and the third heterogeneous material have different etching rates.

[0049] Among them, such as Figure 2As shown in FIG. b), the film layer located on the sapphire substrate 10 is a heterogeneous layer 20, which can be a porous heterogeneous layer or a composite heterogeneous layer. Taking the porous heterogeneous layer as an example, it is a film layer made of a heterogeneous material. The heterogeneous material is actually relative to the sapphire substrate 10 and the epitaxial layer material, such as gallium nitride, that is, a material different from the sapphire substrate 10 and the epitaxial material. Specifically, it can be SiO2. Since it is difficult for the epitaxial material to grow on the heterogeneous material, the heterogeneous material has the effect of inhibiting the growth of the epitaxial material. The first heterogeneous material forms a heterogeneous layer on the substrate by deposition. The thin film deposition technology can be any of the existing means, including but not limited to vacuum evaporation or magnetron sputtering in physical vapor deposition, plasma enhanced chemical vapor deposition (PECVD) in chemical vapor deposition, etc., which are not limited here. The term "porous heterogeneous layer" refers to the uneven pores left behind during the deposition process due to the stacking of particles of different shapes and sizes. By adjusting the temperature, power, and duration of the deposition to change the size of the deposited particles, a porous heterogeneous layer with a predetermined porosity can be obtained. In other words, the porous heterogeneous layer in this embodiment can be controlled to obtain a predetermined porosity by adjusting the preparation process and its parameters.

[0050] continue Figure 2 As shown in FIG. b), the film layer on the sapphire substrate 10 can also be considered as a composite heterogeneous layer. The composite heterogeneous layer contains at least two heterogeneous materials, including a second heterogeneous material and a third heterogeneous material. The second heterogeneous material is the main material and can be SiO2 or SiN x or Si, but not limited to the above materials. The third heterogeneous material is an auxiliary material, a dielectric material with different etching resistance than the main material, such as aluminum oxide, aluminum nitride, etc. Mixed deposition can be achieved by simultaneously depositing the two heterogeneous materials through deposition, or by alternating the two heterogeneous materials on the sapphire substrate 10. By adjusting the preparation process and parameters, the predetermined doping ratio of the two heterogeneous materials in the composite heterogeneous layer can also be controlled.

[0051] The mixed deposition of two heterogeneous materials with different refractive indices can regulate the refractive index of the heterogeneous layer after deposition, thereby increasing the refractive index difference between the heterogeneous layer and the substrate, improving the light path, increasing the luminous flux passing through the substrate, and improving the light extraction rate.

[0052] Alternatively, temperature control can be used to deposit a film with a porous interior and a smooth surface, a dense interior and a roughened surface, or a dense interior and a smooth surface. Low-temperature deposition significantly reduces the effects of thermal stress, preventing film cracking and subsequent epitaxial growth abnormalities caused by excessive stress. Low-temperature deposition can also form a film structure with a porous interior and a roughened surface.

[0053] S130 , patterning the composite heterogeneous layer with a preset doping ratio or the porous heterogeneous layer with a preset porosity through an etching process to form a plurality of first heterogeneous microstructures with a preset surface roughness.

[0054] Among them, such as Figure 2 As shown in Figure c), patterning refers to a method of preparing a substrate with a preset surface roughness of a microstructure by masking and etching on a substrate. Due to the different etching resistance of different layers, the etching effects achieved by physical or chemical etching methods are different, and multiple first heterogeneous microstructures 40 with preset surface roughness are obtained, which together constitute a substrate with a certain pattern. Etching methods include but are not limited to ion milling, plasma etching, reactive ion etching and chemical etching. The mask layer 30 is a commonly used tool in the etching process, not limited to photoresist and other heterogeneous materials, and is not limited here. For example, it can be photolithography exposure or nanoimprinting. Among them, photolithography exposure refers to a photolithography technology that transfers the pattern on the mask to the substrate with the help of photoresist under the action of light, and then uses a developer to dissolve the photoresist in the exposed area of ​​the positive photoresist or the non-exposed area of ​​the negative photoresist, thereby forming a three-dimensional pattern on the photoresist. Nanoimprinting is a technology that uses photoresist to transfer the micro-nano structure on the template to the material to be processed by applying pressure. Optionally, the mask pattern arrangement can be a periodic square lattice arrangement, a periodic hexagonal close-packed arrangement, a non-periodic quasicrystal arrangement, and a random array arrangement, etc., which are not limited here. It should be noted that the first heterogeneous microstructure 40 formed in this step has a preset surface roughness. The fundamental reason is that the porous heterogeneous layer has a preset porosity, or the composite heterogeneous layer has a preset doping ratio. During the etching process, due to the fixed etching rate difference, a preset surface roughness can be formed. In other words, in this embodiment, according to the correspondence between the porosity of the porous heterogeneous layer or the doping ratio in the composite heterogeneous layer and the surface roughness of the first heterogeneous microstructure 40 finally formed, the surface roughness of the first heterogeneous microstructure 40 finally formed can be regulated by the porosity of the porous heterogeneous layer or the doping ratio of the composite heterogeneous layer, thereby achieving the expected patterned substrate to meet the needs of LEDs.

[0055] Embodiments of the present invention provide a method for preparing a patterned substrate, comprising providing a sapphire substrate; depositing a first heterogeneous material on the substrate to form a porous heterogeneous layer with a preset porosity, or depositing a mixture of at least two heterogeneous materials to form a composite heterogeneous layer with a preset doping ratio; and patterning the composite heterogeneous layer or the porous heterogeneous layer through an etching process to form multiple first heterogeneous microstructures with a preset surface roughness. Embodiments of the present invention provide a method for regulating the surface roughness of patterns in a patterned substrate. The multiple first heterogeneous microstructures with a preset surface roughness can promote the bending of dislocations within the epitaxial layer along the sides of the pattern and the closure of the pattern at the top, thereby improving the crystal quality of the epitaxial material. The large refractive difference between the substrate and the heterogeneous material can also improve light extraction efficiency.

[0056] Optionally, in the above step S120, depositing a first heterogeneous material on the sapphire substrate to form a porous heterogeneous layer with a preset porosity may specifically include:

[0057] The first heterogeneous material is deposited in a low-temperature environment to form the porous heterogeneous layer with a preset porosity, wherein the temperature of the low-temperature environment is lower than 100°C.

[0058] Among them, since low-temperature deposition conditions can significantly reduce the influence of thermal stress, the deposition position and bonding order of the particles can be changed during the deposition process, forming a film structure with an internal porous surface roughening, preventing film cracking caused by excessive stress and subsequent epitaxial stacking abnormalities.

[0059] Optionally, in step S120, after depositing a first heterogeneous material on the sapphire substrate to form a porous heterogeneous layer with a preset porosity, the method further includes:

[0060] The porous heterogeneous layer is surface modified to make the porous heterogeneous layer hydrophobic.

[0061] Among them, due to the high porosity of the heterogeneous layer formed by low-temperature deposition, it is very easy to absorb water molecules and other particulate foreign matter in the atmosphere due to its large surface area and capillary action under natural conditions, resulting in poor environmental stability of the film layer. In addition, due to the influence of adsorbed moisture and particles, the refractive index of the heterogeneous layer will also increase significantly, greatly reducing its optical performance. Therefore, it is necessary to perform surface modification treatment on the film layer. Through the modification treatment, the surface groups of the heterogeneous layer are changed from polar to non-polar, which is also beneficial to subsequent mask coating; the hydrophobic compound can be hexamethyldisilazane (HMDS).

[0062] For example, the substrate with the porous heterogeneous layer can be modified by vacuum evaporation, wherein the temperature is 100°C to 150°C, the vacuum pressure is 0.5kPa to 1kPa, and the time is 5 to 20 minutes, thereby obtaining a polar and non-polar porous heterogeneous layer such as Figure 2c). Optionally, the substrate having the non-polar heterogeneous layer after deposition is subjected to a heat treatment at a temperature of 300° C. to 850° C. for 5 to 20 minutes.

[0063] In a specific embodiment, in step S120, the mixed deposition of at least two heterogeneous materials on the sapphire substrate to form a composite heterogeneous layer with a preset doping ratio may specifically include:

[0064] An ion-assisted electron beam dual-source co-evaporation process is adopted to deposit the second heterogeneous material and the third heterogeneous material in a mixed manner according to at least one of a preset evaporation electron beam power, a preset vacuum pressure and a preset auxiliary radio frequency source power.

[0065] Among them, the ion-assisted electron beam dual-source co-evaporation process is a commonly used physical means for depositing heterogeneous layers. It can deposit two heterogeneous materials at the same time and regulate them separately, including but not limited to preset evaporation electron beam power, preset vacuum pressure and preset auxiliary RF source power. The evaporation electron beam power and preset auxiliary RF source power can adjust the particle size emitted by the deposited heterogeneous material, and the preset vacuum pressure can adjust the evaporation environment. The three together adjust the uniformity, roughness and density of the deposited film, which is suitable for the field of optoelectronic devices, including but not limited to heterogeneous layers of inorganic semiconductor materials.

[0066] For example, the ion-assisted electron beam dual-source co-evaporation technology is used to prepare a heterogeneous layer with a preset doping ratio, with the main material source being SiO2 and the auxiliary material source being AlN. -4 Pa vacuum level, the sapphire substrate is heated to 200 ° C, the deposition rate (material ratio) of the main and auxiliary materials is adjusted by adjusting the power of the evaporation electron beam, and the mixing density of the main and auxiliary materials is adjusted by adjusting the vacuum pressure or the power of the auxiliary RF source. The deposition time is set to prepare the desired mixed film layer with a preset doping ratio;

[0067] In another specific embodiment, in step S120, mixing and depositing at least two heterogeneous materials on the sapphire substrate to form a composite heterogeneous layer with a preset doping ratio may also specifically include:

[0068] A plasma enhanced chemical vapor deposition process is adopted to mix and deposit the second heterogeneous material and the third heterogeneous material in a preset gas source ratio.

[0069] Among them, the plasma-enhanced chemical vapor deposition process refers to the technology of using plasma to activate the reaction gas, promote chemical reactions on the substrate surface or near-surface space, and generate solid films. Under the action of high-frequency or DC electric field, the source gas is ionized to form plasma. Low-temperature plasma is used as the energy source, an appropriate amount of reaction gas is introduced, and plasma discharge is used to activate the reaction gas and realize chemical vapor deposition. The film quality, such as the roughness, uniformity, density and thickness of the heterogeneous film, can be controlled by adjusting the working voltage and frequency, gas source ratio, gas source flow rate and working time.

[0070] Exemplarily, the heterogeneous layer is prepared using PECVD deposition technology at a temperature of 300°C and a pressure below 150 Pa. In the SiO2 deposition gas source environment, the metal organic source trimethylaluminum (TMA) is introduced with nitrogen as the carrier gas, and Al2O3 is added to the main material SiO2. The ratio of the main and auxiliary materials is controlled by adjusting the gas source ratio. After the deposition is completed, a high-temperature heat treatment (750°C and above) is performed for 5 to 15 minutes to control the spatial density distribution of the main and auxiliary materials.

[0071] In another specific embodiment, in step S120, the mixed deposition of at least two heterogeneous materials on the sapphire substrate to form a composite heterogeneous layer with a preset doping ratio may further include:

[0072] A plasma enhanced chemical vapor deposition process is adopted to alternately deposit the second heterogeneous material and the third heterogeneous material at a preset deposition time.

[0073] The second heterogeneous material and the third heterogeneous material are alternately deposited at a preset deposition time, and the spatial density distribution of the second heterogeneous material and the third heterogeneous material is adjusted by changing the preset deposition time.

[0074] Exemplarily, PECVD deposition technology is used to prepare a heterogeneous layer with a preset doping ratio, at a temperature of 300°C and a pressure below 150 Pa. The oxygen-poor SiO2 layer main material can be deposited at a certain gas source silicon / oxygen ratio, and then the oxygen-rich SiO2 layer auxiliary material can be deposited by lowering the gas source silicon / oxygen ratio. The alternating deposition can be repeated. The mixing ratio can be controlled by controlling the deposition time of the main and auxiliary materials, and the mixing density can be controlled by controlling the deposition pressure of the main and auxiliary materials.

[0075] In addition, in step S120, after depositing a first heterogeneous material on the sapphire substrate to form a porous heterogeneous layer with a preset porosity; or after depositing at least two heterogeneous materials on the sapphire substrate to form a composite heterogeneous layer with a preset doping ratio, the method further includes:

[0076] The porous heterogeneous layer or composite heterogeneous layer is heat treated under the conditions of a temperature of 300 to 850° C. and a time of 5 to 20 minutes.

[0077] Among them, heat treatment refers to a thermal processing process in which the material is heated, kept warm and cooled in the solid state to obtain the expected structure and performance. The temperature is increased to change the mechanical properties inside the film layer, eliminate the stress influence on the surface, and make the material more stable and uniform.

[0078] For example, the temperature is 300°C, the pressure is below 150 Pa, PECVD deposition technology is used, nitrogen is used as the carrier gas to introduce the metal organic source, Al2O3 is added to the main material SiO2, and the ratio of the main and auxiliary materials is controlled by adjusting the gas source ratio. After the deposition is completed, high-temperature heat treatment (750°C and above) is performed for 5 to 15 minutes.

[0079] Optionally, the first heterogeneous material and the second heterogeneous material both include silicon dioxide, silicon nitride or silicon; and the third heterogeneous material includes aluminum oxide, aluminum nitride and silicon dioxide.

[0080] Optionally, the refractive index of the third heterogeneous material is lower than that of the second heterogeneous material. In this case, since the third heterogeneous material is doped into the second heterogeneous material, the refractive index of the composite heterogeneous layer with a predetermined doping ratio can be adjusted by using the third heterogeneous material with a low refractive index, that is, the refractive index of the first heterogeneous microstructure can be adjusted. The refractive index of the first heterogeneous microstructure can then be used to improve the light output path of the LED device containing the patterned substrate, thereby increasing light extraction efficiency and improving the light extraction efficiency of the LED device.

[0081] Based on the preparation steps of the above embodiments, the embodiments of the present invention further provide two methods for preparing patterned substrates. Figure 3 is a flow chart of another method for preparing a patterned substrate provided by an embodiment of the present invention. Figure 4 yes Figure 3 The structural flow chart of the method for preparing the patterned substrate shown in FIG. Figure 3 and Figure 4 Based on the above embodiment, in another embodiment of the present invention, after step S230 patterns the composite heterogeneous layer or the heterogeneous layer with pores by etching to form a plurality of first heterogeneous microstructures 40 with a preset surface roughness, the following steps may be further included:

[0082] S240 , using the first heterogeneous microstructure as a mask, patterning the sapphire substrate through an etching process to form a plurality of sapphire microstructures with a preset surface roughness on the surface of the sapphire substrate.

[0083] refer to Figure 4 d) Figure and Figure 4 As shown in FIG. 5 , with the first heterogeneous microstructure 40 as a mask, a sapphire substrate 10 having a sapphire microstructure 41 is obtained after an etching process, and the sapphire substrate 10 can be obtained as shown in FIG. Figure 4e) shows a new patterned structure substrate. It is worth noting that the etching process includes but is not limited to all the etching methods mentioned above, which will not be repeated here. It should also be noted that this step is to use the first heterogeneous microstructure 40 with a preset surface roughness as a mask to prepare a sapphire microstructure. During the etching process, due to the influence of the surface roughness of the first heterogeneous microstructure 40, there will be local etching rate differences on the sapphire substrate 10, and thus a certain surface roughness will also be formed. It can be imagined that the surface roughness of the sapphire microstructure essentially depends only on the surface roughness of the first heterogeneous microstructure 40, so the surface roughness of the sapphire microstructure can be regulated to obtain the expected sapphire patterned substrate with a rough surface.

[0084] Figure 5 is a flow chart of another method for preparing a patterned substrate provided by an embodiment of the present invention. Figure 6 yes Figure 5 The structural flow chart of the method for preparing the patterned substrate shown in FIG. Figure 5 and Figure 6 , based on the above Figure 1 In another embodiment of the present invention, after patterning the composite heterogeneous layer or the heterogeneous layer with pores by etching to form a plurality of first heterogeneous microstructures 40 with a preset surface roughness in step S330, the following steps may be further included:

[0085] S340, depositing a first heterogeneous material on the surface of the first heterogeneous microstructure in a high-temperature environment to form a covering heterogeneous layer, wherein the temperature of the high-temperature environment is higher than 100° C.;

[0086] S350 , patterning the covering heterogeneous layer using an etching process to form a plurality of second heterogeneous microstructures, where the second heterogeneous microstructures include the first heterogeneous microstructures and the covering heterogeneous layer covering the first heterogeneous microstructures.

[0087] In high temperature environment above 100℃ Figure 6 d) The substrate having the first heterogeneous microstructure 40 is subjected to secondary deposition, and the deposited heterogeneous material is covered on the first microstructure to obtain the following Figure 6 As shown in FIG. e), the substrate with the covering heterogeneous layer 50 is formed. The heterogeneous material deposited for the second time can be the same as the heterogeneous material deposited for the first time, but the particle size or structure can be different from that of the heterogeneous material deposited for the first time. It can also be another heterogeneous material. The deposition method includes but is not limited to the method used for the first deposition. Then, the substrate with the covering heterogeneous layer 50 is patterned by an etching process to obtain the following: Figure 6 FIG. f) shows a substrate having a plurality of second heterogeneous microstructures 60 , where the second heterogeneous microstructures 60 include a first heterogeneous microstructure 40 and a covering heterogeneous layer 50 covering the first heterogeneous microstructure 40 .

[0088] It is worth noting that, based on “patterning the composite heterogeneous layer or the porous heterogeneous layer through an etching process to form a plurality of first heterogeneous microstructures with a preset surface roughness”, “using the first heterogeneous microstructure as a mask, patterning the sapphire substrate through an etching process to form a graphic substrate with a plurality of sapphire microstructures with a preset surface roughness on the surface of the sapphire substrate” and “depositing a first heterogeneous material on the surface of the first heterogeneous microstructure in a high-temperature environment to form a covering heterogeneous layer” are parallel schemes, rather than different steps of the same scheme.

[0089] The present invention provides a specific embodiment of the method for preparing a patterned substrate using a porous heterogeneous layer. Figure 3 The process shown in the figure is as follows: providing a sapphire substrate; depositing a first heterogeneous material on the sapphire substrate to form a porous heterogeneous layer with a predetermined porosity; patterning the porous heterogeneous layer through an etching process to form a plurality of first heterogeneous microstructures with a predetermined surface roughness; performing surface modification on the porous heterogeneous layer to make it hydrophobic; and patterning the sapphire substrate through an etching process using the first heterogeneous microstructure as a mask to obtain a new patterned substrate. The specific steps are as follows: Specific embodiment one:

[0091] S01. Depositing a 1.8 to 4 μm thick silicon oxide film layer on a sapphire flat substrate using PECVD technology at 80° C., using a surfactant-containing buffered oxide etchant (BOE) with a 6:1 etching rate ranging from 3500 nm / min to 4000 nm / min, with a surface roughness Ra of approximately 12 nm and a refractive index of approximately 1.35.

[0092] S02: HMDS was used to modify the substrate after step S01 by vacuum evaporation at 150°C and 8KPa for 10 minutes.

[0093] S03: preparing a required mask pattern layer on the surface-modified silicon oxide thin film layer by photolithography technology, wherein the height of the mask pattern layer is between 1.9 and 2.6 μm.

[0094] S04: Etching the wafer after step S03 through a dry etching process to obtain the desired patterned substrate.

[0095] Figure 7 This is an AFM test image of a patterned substrate prepared using existing technology. Figure 8 This is an AFM test image of the patterned substrate prepared in the first embodiment of the present invention. Figure 7 and Figure 8It can be seen that in the patterned substrate prepared in the specific embodiment of the present invention, many evenly arranged conical protrusions are formed on the surface. It can be observed that the surface of the conical protrusions is evenly rough, while the surface of the conical protrusions in the patterned substrate obtained by the prior art is relatively smooth. Therefore, it can be seen that after the operating steps provided in the embodiment of the present invention, a surface roughening structure can be etched on the surface of the heterogeneous layer pattern of the patterned substrate to form micro-pits of corresponding density and size, thereby achieving the effect of micro-scale surface roughness control of the patterned substrate, which is operational.

[0096] In addition, the embodiment of the present invention further provides another specific embodiment for mixed deposition of at least two heterogeneous materials with different etching rates on a sapphire substrate, which may specifically include the following steps: Specific embodiment two:

[0098] S01: PECVD deposition technology is used on a sapphire flat substrate at a temperature of 300°C and a pressure of 80 Pa. In the SiO2 deposition gas source environment, nitrogen is used as a carrier gas to introduce the metal organic source trimethylaluminum (TMA), and the auxiliary material Al2O3 is added to the main material SiO2. By adjusting the gas source ratio to control the ratio of the main and auxiliary materials, a mixed thin film layer with a thickness of 1.8um to 4um is deposited.

[0099] S02: After the deposition is completed, a high-temperature heat treatment (750°C) is performed under low pressure (80 Pa) for 5 to 15 minutes to regulate the spatial density distribution of the main and auxiliary materials.

[0100] S03: A required mask pattern layer is prepared on the heat-treated SiO2 / Al2O3 mixed thin film layer by photolithography technology, and the height of the mask pattern layer is between 1.9 and 2.6 μm.

[0101] S04: Etching the wafer after step S03 through a dry etching process to obtain the desired patterned substrate.

[0102] Figure 9 This is an AFM test image of the patterned substrate prepared in the second embodiment of the present invention. Figure 7 and Figure 9 The patterned substrate prepared in the first embodiment of the present invention has numerous evenly spaced conical protrusions on its surface. Observably, the surface of the conical protrusions is uneven, with distinct and unevenly distributed protrusions. This indicates that, after the steps provided in the second embodiment of the present invention, a surface roughening structure can be etched on the heterogeneous layer pattern surface of the patterned substrate, forming micro-pits and protrusions of a certain density and size. This achieves the effect of mixing different materials in the heterogeneous layer and regulating surface roughness, resulting in a novel patterned substrate.

[0103] The method for preparing a patterned substrate provided in an embodiment of the present invention includes providing a sapphire substrate; depositing a first heterogeneous material on the substrate to form a porous heterogeneous layer with a preset porosity or mixedly depositing at least two heterogeneous materials to form a composite heterogeneous layer with a preset doping ratio; patterning the composite heterogeneous layer or the porous heterogeneous layer through an etching process to form a plurality of first heterogeneous microstructures with a preset surface roughness. The plurality of first heterogeneous microstructures with rough surfaces can promote the closing of dislocations within the epitaxial layer along the sides and at the top of the pattern, thereby improving the crystal quality of the epitaxial material and reducing the stress influence on the substrate surface. At the same time, the patterned substrate can ensure the improvement of the light path. The large refractive difference between the substrate and the heterogeneous material can also improve the light extraction efficiency.

[0104] Based on the same inventive concept, an embodiment of the present invention further provides a patterned substrate. Figure 10 This is a schematic structural diagram of a patterned substrate provided by an embodiment of the present invention, with reference to Figure 10 The patterned substrate is prepared using any of the patterned substrate preparation methods described in the above embodiments. In one specific embodiment, it may include a sapphire substrate 10 and a plurality of first heterogeneous microstructures 40 having a predetermined surface roughness located on the sapphire substrate. In the figure, a patterned heterogeneous layer having raised first heterogeneous microstructures 40 is present on the sapphire substrate 10. The first heterogeneous microstructures 40 are evenly distributed, and the exposed sapphire substrate 10 is neat and smooth.

[0105] Due to the presence of the first heterogeneous microstructure, this structural substrate can promote the closing of dislocations within the epitaxial layer along the sides and top of the pattern, thereby improving the crystal quality of the epitaxial layer material and reducing the stress influence on the substrate surface. At the same time, it ensures that the patterned substrate improves the light path. The large refractive difference between the substrate and the heterogeneous material can also improve the light extraction efficiency.

[0106] Based on the same inventive concept, an embodiment of the present invention further provides an LED epitaxial wafer. Figure 11 This is a schematic diagram of the structure of an LED epitaxial wafer provided by an embodiment of the present invention, with reference to Figure 11 The LED epitaxial wafer includes any patterned substrate provided by the embodiments of the present invention and an epitaxial layer formed on the patterned substrate.

[0107] Different substrate materials require different LED epitaxial wafer growth technologies, chip processing technologies, and device packaging technologies. For the patterned substrate provided in the embodiments of the present invention, the epitaxial layer 70 on the corresponding LED epitaxial wafer can be GaN, AlGaN epitaxial layer, etc. Epitaxial wafer growth technologies include but are not limited to metal organic chemical vapor deposition and other preparation methods.

[0108] The LED epitaxial wafer provided in an embodiment of the present invention is prepared by sequentially forming a predetermined heterogeneous layer and a mask layer 30 on a sapphire substrate 10, patterning the mask layer 30, preparing a patterned substrate, and growing an epitaxial layer 70 based on the patterned substrate. In the patterned substrate, the evenly distributed conical protrusion microstructure can improve and promote the closure of dislocations within the epitaxial layer along the sides and top of the pattern, thereby improving the crystal quality of the epitaxial layer material and reducing the stress effect on the substrate surface. At the same time, the patterned substrate improves the light path. The large refractive difference between the substrate and the heterogeneous material can also improve the light extraction efficiency. In addition, the combination of dry etching and wet etching can obtain a patterned substrate with no sapphire over-etching, reducing the lattice defect density when the side-grown GaN epitaxial layers merge, which can effectively improve the yield of LED chips.

[0109] Note that the above are only preferred embodiments of the present invention and the technical principles employed. Those skilled in the art will appreciate that the present invention is not limited to the specific embodiments herein, and that various obvious changes, readjustments, combinations, and substitutions are possible for those skilled in the art 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 scope of the present invention. The scope of the present invention is determined by the scope of the appended claims.

Claims

1. A method for preparing a patterned substrate, characterized in that: include: Providing a sapphire substrate; Depositing a first heterogeneous material on the sapphire substrate to form a porous heterogeneous layer with a preset porosity, and performing surface modification on the porous heterogeneous layer to make the porous heterogeneous layer hydrophobic; or depositing at least two heterogeneous materials on the sapphire substrate to form a composite heterogeneous layer with a preset doping ratio, wherein the at least two heterogeneous materials include a second heterogeneous material and a third heterogeneous material, wherein the second heterogeneous material and the third heterogeneous material have different etching rates, and the refractive index of the third heterogeneous material is lower than that of the second heterogeneous material, thereby increasing the refractive index difference between the composite heterogeneous layer and the sapphire substrate; The composite heterogeneous layer or the heterogeneous layer with pores is patterned by an etching process to form a plurality of first heterogeneous microstructures with a preset surface roughness.

2. The preparation method according to claim 1, characterized in that Depositing a first heterogeneous material on the sapphire substrate to form a porous heterogeneous layer with a preset porosity, comprising: The first heterogeneous material is deposited in a low-temperature environment to form the porous heterogeneous layer with a preset porosity, wherein the temperature of the low-temperature environment is lower than 100°C.

3. The preparation method according to claim 2, characterized in that After patterning the composite heterogeneous layer or the heterogeneous layer with pores by an etching process to form a plurality of first heterogeneous microstructures with a preset surface roughness, the method further includes: The sapphire substrate is patterned by an etching process using the first heterogeneous microstructure as a mask, so as to form a plurality of sapphire microstructures with a preset surface roughness on the surface of the sapphire substrate.

4. The preparation method according to claim 2, characterized in that After patterning the composite heterogeneous layer or the heterogeneous layer with pores by an etching process to form a plurality of first heterogeneous microstructures with a preset surface roughness, the method further includes: Depositing the first heterogeneous material on the surface of the first heterogeneous microstructure in a high-temperature environment to form a covering heterogeneous layer, wherein the temperature of the high-temperature environment is higher than 100° C.; The covering heterogeneous layer is patterned by an etching process to form a plurality of second heterogeneous microstructures, wherein the second heterogeneous microstructures include a first heterogeneous microstructure and a covering heterogeneous layer covering the first heterogeneous microstructure.

5. The preparation method according to claim 1, characterized in that Mixing and depositing at least two heterogeneous materials on the sapphire substrate to form a composite heterogeneous layer with a preset doping ratio, comprising: An ion-assisted electron beam dual-source co-evaporation process is adopted to deposit the second heterogeneous material and the third heterogeneous material in a mixed manner according to at least one of a preset evaporation electron beam power, a preset vacuum pressure, and a preset auxiliary radio frequency source power.

6. The preparation method according to claim 1, characterized in that Mixing and depositing at least two heterogeneous materials on the sapphire substrate to form a composite heterogeneous layer with a preset doping ratio, comprising: The second heterogeneous material and the third heterogeneous material are mixed and deposited in a preset gas source ratio by using a plasma enhanced chemical vapor deposition process.

7. The preparation method according to claim 1, characterized in that Mixing and depositing at least two heterogeneous materials on the sapphire substrate to form a composite heterogeneous layer with a preset doping ratio, comprising: The second heterogeneous material and the third heterogeneous material are alternately deposited with a preset deposition time by using a plasma enhanced chemical vapor deposition process.

8. The preparation method according to claim 1, characterized in that After depositing a first heterogeneous material on the sapphire substrate to form a porous heterogeneous layer with a preset porosity; or after depositing at least two heterogeneous materials on the sapphire substrate to form a composite heterogeneous layer with a preset doping ratio, the method further includes: The porous heterogeneous layer or the composite heterogeneous layer is heat-treated at a temperature of 300 to 850° C. and for 5 to 20 minutes.

9. The preparation method according to claim 1, characterized in that The first heterogeneous material and the second heterogeneous material both include silicon dioxide, silicon nitride or silicon; and the third heterogeneous material includes aluminum oxide, aluminum nitride and silicon dioxide.

10. A patterned substrate, characterized in that: The patterned substrate is prepared by the method for preparing the patterned substrate according to any one of claims 1 to 9.

11. An LED epitaxial wafer, characterized in that: Comprising the patterned substrate as claimed in claim 10.

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