A method for fabricating a highly consistent patterned substrate, the patterned substrate, and an LED epitaxial wafer.

Abstract

This invention provides a method for fabricating a highly uniform patterned substrate, a patterned substrate, and an LED epitaxial wafer. The method first provides a substrate; then, it applies at least one of physical, chemical, or mechanical planarization techniques to perform atomic-level planarization on a first surface to achieve a surface roughness within a certain range, and / or performs atomic-level planarization on a second surface to achieve a surface roughness within a certain range; a photoresist layer is formed on the second surface of the substrate; and the photoresist layer is exposed using a photomask to transfer the pattern on the photomask to the second surface of the substrate. This method solves the problem that due to the roughness of the substrate surface, the exposure beam is reflected and refracted on the substrate surface during the patterning process, resulting in multiple exposures of the photoresist and thus reducing the uniformity of the patterned substrate after etching.

Description

Technical Field

[0001] The embodiments of the present invention relate to the fields of semiconductor manufacturing and microelectronics technology, and particularly to a method for preparing a highly consistent patterned substrate, a patterned substrate, and an LED epitaxial wafer. Background Technology

[0002] In the manufacturing process of semiconductors and optoelectronic devices, the microstructure of the substrate surface has a direct impact on the device performance. With the continuous technological development and updates in the semiconductor industry, the pattern size is constantly decreasing, and the requirements for the quality of epitaxial growth are becoming increasingly stringent. Therefore, the consistency of the pattern within the substrate is becoming increasingly important.

[0003] The microstructure of existing patterned substrates can improve epitaxial quality and luminous efficiency to some extent. However, as pattern sizes become smaller, the properties of the flat substrate itself also affect the stability of the patterning process, leading to uneven patterning and impacting device reliability and performance. In particular, substrate surface roughness causes light to be refracted and repeatedly exposed to the photoresist during the patterning process due to the roughness of the front and back sides. This affects the consistency and stability of the photoresist pillars in the patterning process, ultimately reducing the uniformity of the patterned substrate after etching. Summary of the Invention

[0004] The present invention provides a method for preparing a highly consistent patterned substrate, a patterned substrate, and an LED epitaxial wafer. The method involves planarizing the substrate surface to reduce the refraction of the exposed light caused by the large surface roughness of the substrate during exposure. This would result in multiple exposures of the photoresist, affecting the consistency of the photoresist pillars and consequently reducing the consistency of the patterned substrate after etching.

[0005] In a first aspect, embodiments of the present invention provide a method for fabricating a highly uniform patterned substrate, comprising:

[0006] Provide a substrate;

[0007] The first surface of the substrate is atomically planarized using at least one of physical, chemical, or mechanical planarization techniques to achieve a roughness within a first surface roughness range, and / or the second surface of the substrate is atomically planarized to achieve a roughness within a second surface roughness range; wherein the second surface is the surface to be etched, and the first surface and the second surface are opposite to each other in the substrate thickness direction.

[0008] A photoresist layer is formed on the second surface of the substrate;

[0009] The photoresist layer is exposed using a photomask to transfer the pattern on the photomask to the second surface of the substrate.

[0010] Optionally, at least one of physical, chemical, or mechanical planarization techniques is applied to atomically planarize the first surface of the substrate to achieve a roughness within a first surface roughness range, and / or atomically planarize the second surface of the substrate to achieve a roughness within a second surface roughness range, including:

[0011] Mechanical polishing technology is applied to the first and second surfaces of the sapphire single crystal for mechanical polishing.

[0012] Chemical mechanical polishing (CMP) is used to planarize the first and second surfaces of the sapphire single crystal, so that the roughness of the first surface reaches the first surface roughness range and the roughness of the second surface reaches the second surface roughness range.

[0013] Optionally, a substrate is provided, comprising:

[0014] Provide a 6-inch sapphire single crystal substrate with a diameter of 150mm;

[0015] The first and second surfaces of the sapphire single crystal are mechanically polished using mechanical polishing techniques, including:

[0016] A diamond suspension with a particle size of 1 μm was used as an abrasive to mechanically polish the first and second surfaces of the sapphire single crystal; wherein the polishing pressure was 2-3 N / cm. 2 The grinding speed is 50rpm-80rpm, and the grinding time is 1-2 hours;

[0017] The first and second surfaces of the sapphire single crystal are planarized using chemical mechanical polishing (CMP) technology, including:

[0018] Chemical mechanical polishing (CMP) is used to planarize the first and second surfaces of the sapphire single crystal. The CMP solution is a 1:10 mixture of potassium hydroxide and deionized water; the abrasive particles are silicon dioxide with an average particle size of 0.05 μm-1 μm; the polishing speed is 100-120 rpm; and the polishing pressure is 1-5 N / cm². 2 Polishing time is 30-60 minutes.

[0019] Optionally, at least one of physical, chemical, or mechanical planarization techniques is applied to atomically planarize the first surface of the substrate to achieve a roughness within a first surface roughness range, and / or atomically planarize the second surface of the substrate to achieve a roughness within a second surface roughness range, including:

[0020] The second surface of the substrate is atomically planarized using at least two of physical, chemical, or mechanical planarization techniques to achieve a roughness within a certain range.

[0021] The first surface of the substrate is atomically planarized using one of physical, chemical, or mechanical planarization techniques to achieve a roughness within a first surface roughness range.

[0022] Optionally, the first surface roughness ranges from 0.01 μm to 1 μm.

[0023] Optionally, the second surface roughness ranges from 0 nm to 0.1 nm.

[0024] Optionally, the physical planarization technology includes one or more of physical vapor deposition, physical etching, ion beam polishing, and magnetron sputtering; the chemical planarization technology includes one or more of wet etching, chemical etching, chemical vapor deposition, and chemical mechanical polishing; and the mechanical planarization technology includes precision grinding and polishing processes.

[0025] Optionally, the pressure parameter for the chemical mechanical polishing is 1-5 N / cm. 2 The rotation speed is 60-100 rpm, and the polishing time is 0.5-2 hours. The chemical solution used for the chemical mechanical polishing is a mixture of potassium hydroxide and deionized water in a ratio of 1:10, and the abrasive particles are silicon dioxide with an average particle size of 0.05μm-1μm.

[0026] Secondly, embodiments of the present invention also provide a patterned substrate, which is prepared using the preparation method of a high-consistency patterned substrate as described in any one of the first aspects of the present invention.

[0027] Thirdly, embodiments of the present invention also provide an LED epitaxial wafer, including a patterned substrate as described in the second aspect of the present invention.

[0028] This invention provides a method for fabricating a highly consistent patterned substrate, a patterned substrate, and an LED epitaxial wafer. The method first provides a substrate; then, it applies at least one of physical, chemical, or mechanical planarization techniques to perform atomic-level planarization on a first surface to achieve a surface roughness within a certain range, and / or performs atomic-level planarization on a second surface to achieve a surface roughness within a certain range; wherein the second surface is the surface to be etched, and the first and second surfaces are opposite to each other in the substrate thickness direction; a photoresist layer is formed on the second surface of the substrate; and a photoresist layer is exposed using a photomask to transfer the pattern on the photomask to the second surface of the substrate. The above technical solution solves the problem that due to the roughness of the substrate surface, the exposure beam will be refracted and reflected when passing through the substrate during the patterning process, resulting in multiple exposures of the photoresist and affecting the consistency and stability of the photoresist pillars in the patterning process, thus reducing the uniformity of the patterned substrate after etching. By planarizing the substrate surface, the uniformity and consistency of the photoresist pillars can be improved, thereby enhancing the uniformity and consistency of the patterned substrate and improving the reliability and performance of the final device. Attached Figure Description

[0029] Figure 1 This is a schematic flowchart of a method for fabricating a highly consistent patterned substrate according to an embodiment of the present invention;

[0030] Figure 2 This is a schematic diagram of a photoresist pillar structure on a substrate without planarization provided in an embodiment of the present invention;

[0031] Figure 3 This is a schematic diagram of a photoresist pillar structure on a substrate that has undergone planarization processing, provided in an embodiment of the present invention.

[0032] Figure 4 This is a schematic diagram illustrating the effect of a planarized substrate on the concentration of yellow light reflectivity after being applied to a patterning process, according to an embodiment of the present invention.

[0033] Figure 5 This is a schematic flowchart of another method for preparing a highly consistent patterned substrate provided in an embodiment of the present invention. Detailed Implementation

[0034] 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.

[0035] 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.

[0036] 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".

[0037] 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.

[0038] 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".

[0039] Figure 1 This is a schematic flowchart of a method for fabricating a highly consistent patterned substrate according to an embodiment of the present invention. (Refer to...) Figure 1 The method includes:

[0040] S110, Provide a substrate.

[0041] For example, the substrate material can be sapphire wafer, silicon wafer, silicon carbide wafer, aluminum nitride wafer, gallium nitride wafer, diamond, etc., and the present invention does not limit it.

[0042] S120. At least one of physical, chemical or mechanical planarization techniques is applied to perform atomic-level planarization on the first surface of the substrate so that the roughness of the first surface reaches the roughness range of the first surface, and / or to perform atomic-level planarization on the second surface of the substrate so that the roughness of the second surface reaches the roughness range of the second surface; wherein the second surface is the surface to be etched, and the first surface and the second surface are opposite to each other in the thickness direction of the substrate.

[0043] Specifically, when a photoresist layer is formed on a substrate and then patterned using photolithography, the pattern on the photomask is transferred to the substrate under illumination. A development process then forms the required photoresist pillars (mask pattern) on the second surface of the substrate, i.e., the surface to be etched. Based on this mask pattern, dry etching or wet etching, or other etching processes, are used to pattern the surface of the substrate, forming multiple basic raised microstructures on the substrate to obtain a patterned substrate. During this process, when the photoresist layer is exposed to form photoresist pillars, the exposure beam is directed from top to bottom. Due to the roughness of the substrate surface, reflections and refractions occur on both the front (second) and back (first) surfaces, causing secondary exposure of the photoresist pillars. This leads to problems such as uneven morphology, non-concentrated size, and poor uniformity of the photoresist pillars. Since the reflectivity of light is related to surface roughness, controlling the surface roughness of the substrate can reduce reflection and refraction, solving the problem of secondary exposure of photoresist pillars by the exposure light. Therefore, at least one of physical, chemical, or mechanical planarization techniques is used to perform atomic-level planarization on the first surface of the substrate to make the roughness of the first surface reach a first surface roughness range, and / or to perform atomic-level planarization on the second surface of the substrate to make the roughness of the second surface reach a second surface roughness range. For example, the roughness range of the first surface is 0.01μm-1μm, and the roughness range of the second surface is 0nm-0.1nm. That is, atomic-level planarization is performed on the back and front sides of the substrate, making the roughness of the front side of the substrate close to 0nm, so that the exposure light is all directly incident into the substrate, while the roughness of the back side is between 0.01μm and 1μm, which will not cause the back side roughness to be too low, so that the incident light can basically penetrate the substrate and be absorbed by the substrate too little, thereby reducing the exposure efficiency.

[0044] In an optional embodiment of the present invention, after planarizing any one surface of the substrate, the surface roughness of the substrate is detected by atomic force microscopy (AFM). After determining that it has reached the roughness range, the reflectivity of the substrate surface is detected by an automated optical inspection system. If the required optical index is still not met, atomic-level planarization is performed on the other surface.

[0045] Figure 2 This is a schematic diagram of a photoresist pillar structure on a substrate without planarization, provided in an embodiment of the present invention. Figure 3 This is a schematic diagram of a photoresist pillar structure on a planarized substrate provided in an embodiment of the present invention. (Refer to...) Figure 2 , Figure 3Substrates without planarization exhibit significantly smaller diameters at the base of the photoresist pillars, while those with planarization show significantly larger diameters. This means that on unplanarized substrates, light passing through the back surface is not parallel to the incident light due to the roughness, resulting in secondary exposure at the bottom of the photoresist layer and consequently a reduction in the size of the photoresist pillar base after development. On planarized substrates, the surface reaches atomic level, reducing light reflection and subsequent multiple exposures to the photoresist; however, the increased roughness of the substrate widens the air gap between it and the stage, still promoting light reflection and affecting exposure uniformity.

[0046] To further verify the impact of planarization on the reflectivity (Mean value) of photoresist pillars in the subsequent PSS process, a batch of planarized 6-inch substrates and unplanarized 6-inch substrates were fed into the substrates separately. Figure 4 This is a schematic diagram illustrating the effect of a planarized substrate applied to a patterning process on the concentration of yellow light reflectivity, according to an embodiment of the present invention. (Reference) Figure 4 After planarization, the concentration of PSS yellow light reflectance is significantly improved. The mean reflectance value in the yellow light process increases from 74.9% to 86.6%, effectively improving the yellow light yield of the PSS process. This not only reduces the difficulty of process control but also reduces the number of reworked wafers and lowers costs.

[0047] S130, A photoresist layer is formed on the second surface of the substrate.

[0048] Specifically, after planarizing the first and / or second surfaces of the substrate, performing a patterning process on these surfaces ensures high consistency. Therefore, a photoresist layer can be formed on the second surface, i.e. the upper surface, of the substrate, so that the photoresist layer can be exposed subsequently to form uniform photoresist pillars.

[0049] The method of forming the photoresist layer is not limited in this embodiment of the invention. Those skilled in the art can choose according to actual needs, such as by means of uniform coating, but not limited thereto.

[0050] S140. The photoresist layer is exposed using a photomask to transfer the pattern on the photomask to the second surface of the substrate.

[0051] For example, in a lithography machine, a photoresist layer is exposed using a photomask, and then a development process is performed to obtain photoresist pillars corresponding to the desired mask pattern on the surface of the substrate to be etched, i.e., the front side. At this time, because the substrate surface has undergone planarization treatment, the uniformity and consistency of the obtained photoresist pillars are greatly improved. The specific implementation method of the development process is not limited in this embodiment of the invention; those skilled in the art can set it according to actual needs. For example, a developing solution can be used to dissolve the photoresist in the exposed area of ​​the positive photoresist and the non-exposed area of ​​the negative photoresist to obtain photoresist pillars, but the method is not limited to the above.

[0052] This invention provides a method for fabricating a highly consistent patterned substrate. First, a substrate is provided. Then, at least one of physical, chemical, or mechanical planarization techniques is applied to perform atomic-level planarization on a first surface of the substrate to achieve a surface roughness within a certain range. And / or, atomic-level planarization is performed on a second surface of the substrate to achieve a surface roughness within a certain range. A photoresist layer is formed on the second surface of the substrate. Finally, a photoresist layer is exposed using a photomask to transfer the pattern on the photomask to the second surface of the substrate. This solution addresses the problem that, due to substrate surface roughness, the exposure beam refracts and reflects as it passes through the substrate during the patterning process, causing multiple exposures of the photoresist. This affects the consistency and stability of the photoresist pillars in the patterning process, ultimately reducing the uniformity of the patterned substrate after etching. By planarizing the substrate surface, the uniformity and consistency of the photoresist pillars can be improved, thereby enhancing the uniformity and consistency of the patterned substrate, ensuring the growth effect of the epitaxial layer on the patterned substrate, and improving the reliability and performance of the final device.

[0053] It should be noted that physical planarization technology includes one or more of physical vapor deposition, physical etching, ion beam polishing, and magnetron sputtering; chemical planarization technology includes one or more of wet etching, chemical etching, chemical vapor deposition, and chemical mechanical polishing; and mechanical planarization technology includes precision grinding and polishing processes.

[0054] It is understandable that the back side of the unplanarized substrate, i.e., the first surface, has a rough structure, and the back side of the substrate is in contact with the photolithography stage. In this case, when light passes through the back side of the substrate, it may be reflected at the gap between the substrate and the photolithography stage. Therefore, performing atomic-level planarization on the back side of the substrate, i.e., the first surface, will make the substrate and the photolithography stage fit tightly together, avoiding the reflection of the light beam at the gap between the substrate and the photolithography stage.

[0055] In an optional embodiment of the present invention, only one planarization technique may be used to planarize the first and second surfaces of the substrate. In this case, the planarization time can be controlled so that the two surfaces meet their respective roughness ranges. Alternatively, different combinations of planarization techniques may be selected to meet their respective roughness ranges. The present invention does not limit this.

[0056] For example, if chemical planarization technology is selected to planarize the first and second surfaces of the substrate, the polishing solution may include, but is not limited to, SiO2, Al2O3, TiO2, MgO, iron oxide, etc. Different chemical solutions can be used to treat the front and back sides of the substrate to achieve different atomic-level planarization effects.

[0057] For example, if physical planarization technology is selected to planarize the first and second surfaces of the substrate, different polishing pressures and speeds can be used to achieve different atomic-level planarization effects for the different planarization requirements of the two surfaces.

[0058] In an optional embodiment of the present invention, the above-described step S120, applying at least one of physical, chemical, or mechanical planarization techniques to perform atomic-level planarization on the first surface of the substrate so that the roughness of the first surface reaches a first surface roughness range, and / or performing atomic-level planarization on the second surface of the substrate so that the roughness of the second surface reaches a second surface roughness range, includes:

[0059] Mechanical polishing technology is applied to mechanically polish the first and second surfaces of the substrate.

[0060] Specifically, since the defects on the substrate surface include both large macroscopic defects and small microscopic defects, mechanical polishing technology is first used to mechanically polish the first and second surfaces of the substrate to remove macroscopic defects.

[0061] For example, a diamond suspension with a particle size of 1 μm can be used as an abrasive, and a precision mechanical polishing machine equipped with a dedicated sapphire polishing pad can be used to mechanically polish the first and second surfaces of a sapphire single crystal; wherein the abrasive pressure of the mechanical polishing is 2-3 N / cm. 2 The grinding speed is 50rpm-80rpm, and the grinding time is 1-2 hours.

[0062] Chemical mechanical polishing (CMP) is used to planarize the first and second surfaces of the substrate so that the roughness of the first surface reaches the first surface roughness range and the roughness of the second surface reaches the second surface roughness range.

[0063] Specifically, after removing macroscopic defects, to further ensure atomic-level planarization, chemical mechanical polishing (CMP) is used to further planarize the first and second surfaces of the substrate. For example, the CMP solution is a 1:10 mixture of potassium hydroxide and deionized water, the abrasive particles are silicon dioxide with an average particle size of 0.05 μm-1 μm, the polishing speed is 100-120 rpm, and the polishing pressure is 1-5 N / cm. 2 The polishing time is 30-60 minutes. It should be noted that since the roughness requirements of the first surface and the second surface are different, the polishing time can also be different; for example, the first surface can be polished for 30 minutes, while the second surface, i.e. the front surface, has a higher roughness requirement, so it can be polished for 50 minutes to achieve a better flattening effect.

[0064] Figure 5 This is a schematic flowchart of another method for fabricating a highly consistent patterned substrate provided in an embodiment of the present invention. (Refer to...) Figure 5 The preparation method of this invention includes the following steps:

[0065] S210, Provide a substrate.

[0066] S220. At least two of physical, chemical or mechanical planarization techniques are used to atomically planarize the second surface of the substrate so that the roughness of the second surface reaches the roughness range of the second surface.

[0067] Specifically, during subsequent coating and exposure development, the exposure beam travels from top to bottom, meaning the beam first reaches the front surface of the substrate, also known as the second surface. To ensure the light passes through the front surface as directly as possible and minimizes reflection and refraction, the second surface needs to be as flat as possible. Therefore, at least two of the physical, chemical, or mechanical planarization techniques can be used to perform atomic-level planarization on the second surface, bringing its roughness within a certain range, thus achieving a high degree of planarization. Using at least two planarization techniques ensures a good planarization effect and further improves the planarization efficiency of the front surface of the substrate.

[0068] S230. Using one of physical, chemical or mechanical planarization techniques, an atomic-level planarization process is performed on the first surface of the substrate so that the roughness of the first surface reaches the first surface roughness range.

[0069] Specifically, during substrate exposure, the exposure light is incident from the front surface (second surface) of the substrate, passes through the substrate to the back surface, i.e., the first surface. The back surface is relatively rough, which can cause the exposure light beam to be reflected, refracted, and diffracted, potentially leading to secondary exposure. Therefore, it is necessary to control the roughness of the back surface. That is, the first surface of the substrate is atomically planarized to bring its roughness within the acceptable range. At the same time, if the back surface roughness is too low, most of the exposure light incident on the substrate will pass through the back surface, thus reducing exposure efficiency. Therefore, the back surface roughness requirement is relatively low, for example, it can be 0.3μm-0.4μm. At this time, one of the physical, chemical, or mechanical planarization techniques can be used to atomically planarize the first surface of the substrate. Compared with the front surface of the substrate, which has a higher degree of planarization, the back surface only requires one planarization process to meet the planarization requirements, which can reduce costs.

[0070] S240, A photoresist layer is formed on the second surface of the substrate.

[0071] S250. The photoresist layer is exposed using a photomask to transfer the pattern on the photomask to the second surface of the substrate.

[0072] The specific implementation of the above steps is the same as in the above embodiments, and will not be repeated here.

[0073] The technical solution of this invention applies at least two of physical, chemical, or mechanical planarization techniques to perform atomic-level planarization on the second surface of the substrate, so that the roughness of the second surface reaches the roughness range of the second surface; and applies one of physical, chemical, or mechanical planarization techniques to perform atomic-level planarization on the first surface of the substrate, so that the roughness of the first surface reaches the roughness range of the first surface; this can satisfy the planarization requirements of the first and second surfaces of the substrate while improving planarization efficiency and controlling costs.

[0074] Based on the same inventive concept, this embodiment of the invention also provides a patterned substrate, which is prepared by the high-consistency patterned substrate preparation method provided in any embodiment of the invention; the patterned substrate includes a substrate and patterned microstructures located on the substrate.

[0075] Because the high-uniformity patterned substrate fabrication method provided in this invention can improve the uniformity and consistency of photoresist pillars, the patterned substrate fabricated based on this method can effectively improve the range and uniformity of the patterned microstructure on the substrate, increase the concentration and hit rate of the product, and thus improve the success rate and stability of subsequent processes. The patterned substrate provided in this invention includes all the technical features and corresponding beneficial effects of the high-uniformity patterned substrate fabrication method provided in any embodiment of this invention, which will not be repeated here.

[0076] This invention also provides an LED epitaxial wafer. Since the LED epitaxial wafer includes the patterned substrate in the above embodiments, it has the corresponding beneficial effects of the patterned substrate provided in this invention, which will not be elaborated here.

[0077] 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 method for fabricating a highly uniform patterned substrate, characterized in that, include: Provide a substrate; The substrate's first surface is atomically planarized using at least one of physical, chemical, or mechanical planarization techniques to achieve a roughness within a first surface roughness range; the substrate's second surface is also atomically planarized to achieve a roughness within a second surface roughness range; wherein the second surface is the surface to be etched, and the first and second surfaces are opposite to each other in the substrate thickness direction; the first surface roughness range is 0.01 μm-1 μm; and the second surface roughness range is 0 nm-0.1 nm. A photoresist layer is formed on the second surface of the substrate; The photoresist layer is exposed using a photomask to transfer the pattern on the photomask to the second surface of the substrate.

2. The preparation method according to claim 1, characterized in that, The method involves atomically planarizing a first surface of the substrate using at least one of physical, chemical, or mechanical planarization techniques to achieve a roughness within a first surface roughness range, and atomically planarizing a second surface of the substrate to achieve a roughness within a second surface roughness range, comprising: The first and second surfaces of the substrate are mechanically polished using mechanical polishing technology. Chemical mechanical polishing (CMP) is used to planarize the first and second surfaces of the substrate so that the roughness of the first surface reaches a first surface roughness range and the roughness of the second surface reaches a second surface roughness range.

3. The preparation method according to claim 2, characterized in that, A substrate is provided, comprising: Provide a 6-inch sapphire single crystal substrate with a diameter of 150mm; The first and second surfaces of the sapphire single crystal are mechanically polished using mechanical polishing techniques, including: A diamond suspension with a particle size of 1 μm was used as an abrasive to mechanically polish the first and second surfaces of the sapphire single crystal; wherein the polishing pressure was 2-3 N / cm. 2 The grinding speed is 50 rpm-80 rpm, and the grinding time is 1-2 hours; The first and second surfaces of the sapphire single crystal are planarized using chemical mechanical polishing (CMP) technology, including: Chemical mechanical polishing (CMP) is used to planarize the first and second surfaces of the sapphire single crystal. The CMP solution is a 1:10 mixture of potassium hydroxide and deionized water; the abrasive particles are silicon dioxide with an average particle size of 0.05 μm-1 μm; the polishing speed is 100-120 rpm; and the polishing pressure is 1-5 N / cm². 2 Polishing time is 30-60 minutes.

4. The preparation method according to claim 1, characterized in that, The method involves atomically planarizing a first surface of the substrate using at least one of physical, chemical, or mechanical planarization techniques to achieve a roughness within a first surface roughness range, and atomically planarizing a second surface of the substrate to achieve a roughness within a second surface roughness range, comprising: The second surface of the substrate is atomically planarized using at least two of physical, chemical, or mechanical planarization techniques to achieve a roughness within a certain range. The first surface of the substrate is atomically planarized using one of physical, chemical, or mechanical planarization techniques to achieve a roughness within a first surface roughness range.

5. The preparation method according to claim 1, characterized in that, The physical planarization technology includes one or more of physical vapor deposition, physical etching, ion beam polishing, and magnetron sputtering; the chemical planarization technology includes one or more of wet etching, chemical etching, chemical vapor deposition, and chemical mechanical polishing; and the mechanical planarization technology includes precision grinding and polishing processes.

6. The preparation method according to claim 5, characterized in that, The pressure parameter for the chemical mechanical polishing is 1-5 N / cm. 2 The rotation speed is 60-100 rpm, and the polishing time is 0.5-2 hours. The chemical solution used for the chemical mechanical polishing is a mixture of potassium hydroxide and deionized water in a ratio of 1:10, and the abrasive particles are silicon dioxide with an average particle size of 0.05μm-1μm.

7. A patterned substrate, characterized in that, It is prepared using the method for preparing a highly consistent patterned substrate as described in any one of claims 1-6.

8. An LED epitaxial wafer, characterized in that, Includes the patterned substrate as described in claim 7.

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