A method of cleaning a silicon carbide substrate

Abstract

The application discloses a cleaning method of a silicon carbide substrate. The method comprises the following steps: firstly, removing the polishing liquid, strongly adsorbed substances and large particles remaining on the surface of a ceramic disc and the silicon carbide substrate by adopting a hydrogen peroxide ultrasonic immersion method; then, immersing the ceramic disc and the silicon carbide substrate in isopropyl alcohol to dissolve the wax on the surface and the edge, remove the surface wax, and reduce the adsorption of the wax between the silicon carbide substrate and the ceramic disc; further, the method is beneficial to realize wafering at low temperature, avoid high-temperature wax dry setting, and increase the cleaning difficulty; then, the wax is removed by immersing the ceramic disc and the silicon carbide substrate in isopropyl alcohol again; finally, the two-step wax removal cleaning process and the ultrasonic cleaning process of super-pure water are adopted to realize the purpose of removing the residual substances without dead angle; in addition, the service life of the wax removal cleaning liquid is effectively prolonged, and the generation amount of the cleaning waste liquid is reduced, so that the application discloses a high-efficiency, green and environment-friendly cleaning method of the silicon carbide substrate.

Description

Technical Field

[0001] This invention relates to the field of semiconductor manufacturing technology, and in particular to a method for cleaning silicon carbide substrates. Background Technology

[0002] With the continuous development of China's semiconductor manufacturing industry, SiC, as a third-generation semiconductor material, has been widely used in metallurgy, chemical industry, semiconductor manufacturing, and other industrial fields. During SiC substrate preparation, to achieve better polishing and grinding effects and prevent the SiC substrate from shifting and fragmenting during processing, liquid wax is typically used to fix the SiC substrate on a ceramic disk before mechanical polishing and chemical mechanical polishing. After polishing, the surface of the SiC substrate will be contaminated with various impurities, polishing fluid, wax residue, and other pollutants. These contaminants can severely affect the performance and reliability of devices.

[0003] Currently, the commonly used method in the industry for removing surface contaminants from SiC substrates involves chemical mechanical polishing followed by rinsing the ceramic disk with a water gun, high-temperature wafer removal, and then a combination of dewaxing and RCA cleaning. This cleaning combination places high demands on the temperature, cleaning capacity, and cleaning solution lifespan of the dewaxing process. High-temperature wafer removal completely melts the wax, facilitating the detachment of the SiC substrate from the ceramic disk. However, excessively high temperatures can cause the wax to lose moisture too quickly, leading to faster drying and hardening. Furthermore, many stages of the SiC substrate cleaning process require jamming during transport, resulting in insufficient contact between the cleaning solution and the SiC substrate edges, thus affecting the cleaning effect at the substrate edges. Moreover, conventional dewaxing processes often use high-concentration dewaxing solutions for agitation cleaning, leaving a large amount of residual wax that is difficult to separate. This causes the cleaning solution to become cloudy after a period of use, significantly reducing its cleaning capacity, necessitating frequent solution replacements to achieve better cleaning results. High-temperature wafer removal and frequent solution replacements not only significantly increase the production cost of SiC substrates but also result in high energy consumption, generate a large amount of waste liquid, and are environmentally unfriendly. Therefore, how to effectively remove residual wax from the edges of SiC substrates while effectively reducing the amount of cleaning solution used and the energy consumption of cleaning is a bottleneck problem that urgently needs to be solved in the current SiC substrate production process. Summary of the Invention

[0004] To address the problems of incomplete removal of residual wax from SiC substrate edges and high energy consumption and large volume of cleaning solution used in existing technologies, this invention provides a cleaning method for silicon carbide substrates. This invention involves a two-step dewaxing process: a pre-cleaning process followed by high-pressure water rinsing of the chemically mechanically polished SiC substrate, and then a low-temperature wafer-laying method. This achieves complete removal of residual wax from the SiC substrate edges, effectively reduces production energy consumption, and increases the lifespan of the dewaxing cleaning solution and subsequent cleaning solutions, making it highly valuable for widespread application.

[0005] To solve the above-mentioned technical problems, the technical solution provided by the present invention is as follows:

[0006] A method for cleaning a silicon carbide substrate, wherein the silicon carbide substrate is a silicon carbide substrate adhered to a ceramic disk after chemical mechanical polishing, and the cleaning method includes the following steps:

[0007] S1, the silicon carbide substrate to be cleaned is rinsed with high-pressure water, and the rinsed silicon carbide substrate is ultrasonically immersed in hydrogen peroxide solution and isopropanol solution in sequence, and then unloaded, separating the silicon carbide substrate from the ceramic disk to obtain silicon carbide substrate I; the unloading temperature is 30℃~40℃.

[0008] S2, the silicon carbide substrate I is placed in isopropanol, heated, and ultrasonically immersed to obtain silicon carbide substrate II;

[0009] S3, after rinsing the silicon carbide substrate II with high-pressure water, it is placed in a mixed solution of dewaxing water and water, heated, and ultrasonically immersed to obtain silicon carbide substrate III;

[0010] S4, after rinsing the silicon carbide substrate III with high-pressure water, it is placed in a mixed solution of dewaxing water, hydrogen peroxide and water, heated and ultrasonically immersed to obtain silicon carbide substrate IV.

[0011] S5, the silicon carbide substrate IV is subjected to ultrapure water frequency conversion ultrasonic cleaning to obtain a clean silicon carbide substrate.

[0012] Compared to existing technologies, the silicon carbide substrate cleaning method provided by this invention adds a pre-cleaning process before dewaxing. First, hydrogen peroxide ultrasonic immersion is used to remove residual polishing liquid, highly absorbent substances, and large particles from the ceramic disk and silicon carbide substrate surface. Then, isopropanol is used to immerse the ceramic disk and silicon carbide substrate, dissolving the wax on the surface and edges. This removes surface wax while reducing wax adsorption between the silicon carbide substrate and the ceramic disk, thus facilitating low-temperature wafer unloading and avoiding high-temperature wax drying which increases cleaning difficulty. Next, a second isopropanol solution water bath heating immersion is performed to remove wax. Finally, a two-step dewaxing cleaning process and ultrapure water frequency conversion ultrasonic cleaning process are used to achieve the goal of removing residues from the silicon carbide substrate without dead angles. Furthermore, the added pre-cleaning process reduces the pressure on subsequent dewaxing cleaning, extending the service life of the dewaxing cleaning solution and subsequent cleaning solutions by 1.6 to 2 times, effectively reducing production energy consumption and costs, and reducing the amount of cleaning waste liquid generated. This is a highly efficient, green, and environmentally friendly silicon carbide substrate cleaning method with high application value.

[0013] It should be noted that after adopting the cleaning process described above, conventional RCA cleaning can be performed, and the silicon carbide substrate after RCA cleaning can be used for subsequent processing.

[0014] Further, in step S1, the rinsing pressure of the high-pressure water rinsing is 2MPa to 3MPa, the rinsing time is 3min to 6min, the rinsing method is double-sided rotary rinsing, and the angle between the silicon carbide substrate and the horizontal plane during rotary rinsing is 45° to 90°.

[0015] The preferred rinsing method can effectively remove residual polishing liquid from the surface of ceramic discs and silicon carbide substrates, and can achieve the purpose of cleaning without dead corners.

[0016] It should be noted that when the high-pressure water gun is used for rotating rinsing, the angle between the silicon carbide substrate and the horizontal plane can vary between 45° and 90°, or a fixed angle can be maintained during rotation. The specific choice can be made according to the actual situation.

[0017] Further, in step S1, the hydrogen peroxide solution is a mixed solution of hydrogen peroxide and water with a volume ratio of 1:20 to 1:30.

[0018] Furthermore, in step S1, the ultrasonic immersion power of the hydrogen peroxide solution is 30KHz to 60KHz, and the ultrasonic immersion time is 10min to 20min.

[0019] The preferred hydrogen peroxide immersion conditions can effectively remove organic matter and particles from the surface of the ceramic disc and silicon carbide substrate.

[0020] It should be noted that in steps S1 and S4, the hydrogen peroxide is commercially available hydrogen peroxide with a mass concentration of 30% to 32%.

[0021] Further, in step S1, the isopropanol solution is a mixed solution of isopropanol and water in a volume ratio of 1:2 to 2:5.

[0022] Furthermore, in step S1, the ultrasonic immersion power of the isopropanol solution is 30KHz~60KHz, and the ultrasonic immersion time is 3min~5min.

[0023] The preferred isopropanol immersion conditions can effectively remove wax from the surface of the ceramic disk and silicon carbide substrate, and reduce the adsorption of wax between the ceramic disk and silicon carbide substrate, thus providing conditions for low-temperature wafer cutting.

[0024] Specifically, in step S1, during the hydrogen peroxide solution immersion and isopropanol solution immersion, the ceramic discs can be vertically immersed in the hydrogen peroxide solution or isopropanol solution using fixing clips, and the immersion should be performed sequentially according to the order in which the chemical mechanical polishing was completed. The hydrogen peroxide solution should be replaced every 80-100 discs, and the isopropanol solution should be replaced every 20-25 discs to ensure the cleaning effect.

[0025] It should be noted that in step S1, the temperature for soaking in hydrogen peroxide solution and isopropanol solution is room temperature.

[0026] It should be noted that in step S1, after each soaking, a high-pressure water rinse is performed before proceeding to the next step. The rinsing pressure of the high-pressure water rinse is 2MPa to 3MPa, the rinsing time is 3min to 6min, and the rinsing method is double-sided rotational rinsing. During rotational rinsing, the angle between the silicon carbide substrate and the horizontal plane is 45° to 90°.

[0027] Further, in step S2, the isopropanol is placed in a quartz beaker and heated in a water bath.

[0028] Furthermore, in step S2, the ultrasonic immersion power is 60KHz~100KHz, the ultrasonic immersion time is 12min~36min, and the ultrasonic immersion temperature is 50℃~60℃.

[0029] Furthermore, in step S2, during the ultrasonic immersion process, the substrate is rotated 60° to 90° around the central axis of silicon carbide substrate I every 3 to 6 minutes.

[0030] The preferred conditions for the second immersion in isopropanol can fully soften the residual wax on the surface and edges of the silicon carbide substrate, providing a prerequisite for the subsequent removal of residual wax with a wax remover without any dead angles.

[0031] Specifically, during the second isopropanol immersion, the cobalt carbide substrate is placed into a stopper and then into a quartz measuring cup containing isopropanol solution. The quartz measuring cup is then immersed in a pure water ultrasonic bath at a temperature of 50℃~60℃ for ultrasonication.

[0032] Further, in steps S3 and S4, the dewaxing solution comprises the following components in mass percentage: 5%–15% fatty alcohol polyoxyethylene ether, 5%–15% alkanolamide polyoxyethylene ether, 3%–10% polydimethylsiloxane, 2%–10% polyethylene glycol, 3%–10% stearic acid, and the balance being deionized water.

[0033] Furthermore, in step S3, the volume ratio of the dewaxing solution to the deionized water is 1:15 to 1:20.

[0034] Furthermore, in step S3, the ultrasonic immersion power is 60KHz~100KHz, the ultrasonic immersion time is 10min~20min, and the ultrasonic immersion temperature is 55℃~70℃.

[0035] Furthermore, in step S3, while ultrasonically immersing, the silicon carbide substrate II is jiggled up and down at a frequency of 20 times / min to 40 times / min.

[0036] The preferred dewaxing and cleaning method can effectively remove residual wax from the surface of silicon carbide substrates.

[0037] Furthermore, in step S4, the volume ratio of the dewaxing agent, hydrogen peroxide, and deionized water is 1:1:18 to 1:1:38.

[0038] Furthermore, in step S4, the ultrasonic immersion power is 40KHz~60KHz, the ultrasonic immersion time is 10min~20min, and the ultrasonic immersion temperature is 55℃~70℃.

[0039] Furthermore, in step S4, while ultrasonically immersing, the silicon carbide substrate III is shoveled up and down at a frequency of 20 times / min to 40 times / min.

[0040] The preferred second dewaxing cleaning method not only removes residual wax from the surface and edges of the silicon carbide substrate more thoroughly, but also effectively decomposes the organic matter washed off in the cleaning solution, ensuring the cleaning ability of the dewaxing cleaning solution and improving its service life.

[0041] Furthermore, in steps S2 to S4, after each cleaning, ultrapure water frequency conversion ultrasonic cleaning is required. The specific process of frequency conversion ultrasonic cleaning is as follows: first, ultrasonic cleaning at 30KHz to 40KHz for 2 to 5 minutes, then ultrasonic cleaning at 60KHz to 100KHz for 3 to 5 minutes, and repeat the ultrasonic cycle 2 to 4 times.

[0042] The preferred variable frequency ultrasonic cleaning process can further remove particles and residues from the surface of the silicon carbide substrate, thereby improving the cleanliness of the silicon carbide substrate.

[0043] The silicon carbide substrate cleaning method provided by this invention involves layer-by-layer peeling based on the distribution of residues on the surface of the silicon carbide substrate after chemical mechanical polishing. Without damaging the internal structure of the silicon carbide substrate, it achieves thorough removal of surface residues, especially stubborn wax residues at the edges of the substrate. Furthermore, the pre-cleaning process added to the wax cleaning process effectively reduces the wafer unloading temperature, extends the service life of the cleaning solution, reduces the amount of cleaning solution used and the amount of waste liquid generated, lowers environmental pollution and wastewater treatment costs, and is suitable for industrial production applications. It offers significant economic and environmental benefits and has broad application prospects. Attached Figure Description

[0044] Figure 1 This is a particle size distribution image of the silicon carbide substrate obtained in Example 1 after RCA cleaning.

[0045] Figure 2 This is a particle size distribution image of the silicon carbide substrate obtained in Example 2 after RCA cleaning.

[0046] Figure 3This is a particle size distribution image of the silicon carbide substrate obtained in Example 3 after RCA cleaning.

[0047] Figure 4 The image shows the particle size distribution of the silicon carbide substrate obtained in Comparative Example 1 after RCA cleaning.

[0048] Figure 5 The particle size distribution of the silicon carbide substrate obtained in Comparative Example 2 after RCA cleaning is shown in the image.

[0049] Figure 6 The particle size distribution of the silicon carbide substrate obtained in Comparative Example 3 after RCA cleaning is shown.

[0050] Figure 7 The particle size distribution of the silicon carbide substrate obtained in Comparative Example 4 after RCA cleaning is shown.

[0051] Figure 8 The particle size distribution of the silicon carbide substrate obtained in Comparative Example 5 after RCA cleaning is shown.

[0052] Figure 9 The particle size distribution of the silicon carbide substrate obtained in Comparative Example 6 after RCA cleaning is shown.

[0053] Figure 10 The image shows the particle size distribution of the silicon carbide substrate obtained in Comparative Example 7 after RCA cleaning. Detailed Implementation

[0054] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0055] To better illustrate the present invention, further examples are provided below.

[0056] The hydrogen peroxide used in the following examples and comparative examples is commercially available hydrogen peroxide with a mass fraction of 30%.

[0057] The composition of the wax remover is: 10% fatty alcohol polyoxyethylene ether, 10% alkanolamide polyoxyethylene ether, 8% polydimethylsiloxane, 7% polyethylene glycol, 8% stearic acid, and the balance is deionized water.

[0058] Example 1

[0059] This embodiment provides a method for cleaning a silicon carbide substrate, including the following steps:

[0060] S1. The SiC substrate and ceramic disk after chemical mechanical polishing are rinsed with a high-pressure water gun. The water gun rinsing pressure is 2.5MPa, the rinsing time is 4min, and the rinsing method is double-sided rotary rinsing. During rotary rinsing, the angle between the silicon carbide substrate and the horizontal plane is 45° to 90°.

[0061] S2, the rinsed SiC substrate and ceramic disk are vertically immersed in hydrogen peroxide solution for room temperature ultrasonic immersion, wherein the volume ratio of hydrogen peroxide to water in the hydrogen peroxide solution is 1:25, the immersion time is 15 min, and the ultrasonic frequency is 45KHz.

[0062] S3. After rinsing the silicon carbide substrate and ceramic disk with high-pressure water, immerse them in an isopropanol solution and sonicate them at room temperature. The volume ratio of isopropanol to water in the isopropanol solution is 9:20, the immersion time is 4 min, and the ultrasonic frequency is 45 kHz.

[0063] S4. After rinsing the silicon carbide substrate and ceramic disk with high-pressure water and drying them, place them on the wafer unloader for wafer unloading. The unloading temperature is 35℃ and the unloading speed is 5 wafers / min. Remove the silicon carbide wafer and place it into the cassette.

[0064] S5, the cartridge containing the silicon carbide substrate is immersed in isopropanol. During the ultrasonic immersion process, the silicon carbide substrate I is rotated around the central axis once every 5 minutes, and the rotation angle is 60° each time. The isopropanol is placed in a quartz measuring cup, and the quartz measuring cup is ultrasonically heated in a water bath at a temperature of 55°C for 30 minutes and an ultrasonic frequency of 80KHz.

[0065] S6. After the silicon carbide substrate is cleaned by ultrapure water frequency conversion ultrasonic cleaning, it is immersed in a mixed solution of dewaxing water and water for up-and-down ultrasonic immersion. The volume ratio of dewaxing water to water is 1:18, the immersion time is 15 min, the immersion temperature is 60℃, the ultrasonic frequency is 80KHz, and the up-and-down immersion frequency is 30 times / min.

[0066] S7. After the silicon carbide substrate is cleaned by ultrapure water frequency conversion ultrasonic cleaning, it is immersed in a mixed solution of dewaxing water, hydrogen peroxide and water for up-and-down ultrasonic immersion. The volume ratio of dewaxing water, hydrogen peroxide and water is 1:1:25, the immersion time is 15 min, the immersion temperature is 65℃, the ultrasonic frequency is 50KHz, and the up-and-down immersion frequency is 30 times / min.

[0067] S8. The silicon carbide substrate is cleaned by ultrapure water frequency conversion ultrasonic cleaning to obtain a clean silicon carbide substrate. The ultrasonic frequency is segmented frequency conversion ultrasonic, first ultrasonic at 35KHz for 4min, then ultrasonic at 80KHz for 4min, and the ultrasonic cycle is repeated 3 times.

[0068] The conditions for high-pressure water rinsing in steps S3 and S4 are the same as those in step S1; the conditions for ultrapure water frequency conversion ultrasonic cleaning in steps S6 and S7 are the same as those in step S8.

[0069] Example 2

[0070] This embodiment provides a method for cleaning a silicon carbide substrate, including the following steps:

[0071] S1. The SiC substrate and ceramic disk after chemical mechanical polishing are rinsed with a high-pressure water gun. The water gun rinsing pressure is 2MPa, the rinsing time is 6min, and the rinsing method is double-sided rotation rinsing. During rotation rinsing, the angle between the silicon carbide substrate and the horizontal plane is 45° to 90°.

[0072] S2, the rinsed SiC substrate and ceramic disk are placed in a vertical hydrogen peroxide solution for room temperature ultrasonic immersion, wherein the volume ratio of hydrogen peroxide to water in the hydrogen peroxide solution is 1:20, the immersion time is 20 min, and the ultrasonic frequency is 60KHz.

[0073] S3. After rinsing the silicon carbide substrate and ceramic disk with high-pressure water, immerse them in an isopropanol solution and sonicate them at room temperature. The volume ratio of isopropanol to water in the isopropanol solution is 1:2, the immersion time is 5 minutes, and the ultrasonic frequency is 60KHz.

[0074] S4. After rinsing the silicon carbide substrate and ceramic disk with high-pressure water and drying them, place them on the wafer unloader for wafer unloading. The unloading temperature is 40℃ and the unloading speed is 6 wafers / min. Remove the silicon carbide wafer and place it into the cassette.

[0075] S5, the cartridge containing the silicon carbide substrate is immersed in isopropanol. During the ultrasonic immersion process, the silicon carbide substrate I is rotated around the central axis once every 6 minutes, and the rotation angle is 60° each time. The isopropanol is placed in a quartz measuring cup, and the quartz measuring cup is ultrasonically heated in a water bath at a temperature of 60°C for 36 minutes. The ultrasonic frequency is 100KHz.

[0076] S6. After the silicon carbide substrate is cleaned by ultrapure water frequency conversion ultrasonic cleaning, it is immersed in a mixed solution of dewaxing water and water for up-and-down ultrasonic immersion. The volume ratio of dewaxing water to water is 1:15, the immersion time is 20 min, the immersion temperature is 70℃, the ultrasonic frequency is 100KHz, and the up-and-down immersion frequency is 40 times / min.

[0077] S7. After the silicon carbide substrate is cleaned by ultrapure water frequency conversion ultrasonic cleaning, it is immersed in a mixed solution of dewaxing water, hydrogen peroxide and water for up-and-down ultrasonic immersion. The volume ratio of dewaxing water, hydrogen peroxide and water is 1:1:18, the immersion time is 20 min, the immersion temperature is 70℃, the ultrasonic frequency is 60KHz, and the up-and-down immersion frequency is 40 times / min.

[0078] S8. The silicon carbide substrate is cleaned by ultrapure water frequency conversion ultrasonic cleaning to obtain a clean silicon carbide substrate. The ultrasonic frequency is segmented frequency conversion ultrasonic, first ultrasonic at 30KHZ for 5min, then ultrasonic at 100KHz for 3min, and the ultrasonic cycle is repeated 4 times.

[0079] The conditions for high-pressure water rinsing in steps S3 and S4 are the same as those in step S1; the conditions for ultrapure water frequency conversion ultrasonic cleaning in steps S6 and S7 are the same as those in step S8.

[0080] Example 3

[0081] This embodiment provides a method for cleaning a silicon carbide substrate, including the following steps:

[0082] S1. The SiC substrate and ceramic disk after chemical mechanical polishing are rinsed with a high-pressure water gun. The water gun rinsing pressure is 3MPa, the rinsing time is 3min, and the rinsing method is double-sided rotary rinsing. During rotary rinsing, the angle between the silicon carbide substrate and the horizontal plane is 45° to 90°.

[0083] S2, the rinsed SiC substrate and ceramic disk are vertically immersed in hydrogen peroxide solution for room temperature ultrasonic immersion, wherein the volume ratio of hydrogen peroxide to water in the hydrogen peroxide solution is 1:30, the immersion time is 10 min, and the ultrasonic frequency is 30KHz.

[0084] S3. After rinsing the silicon carbide substrate and ceramic disk with high-pressure water, immerse them in an isopropanol solution and sonicate them at room temperature. The volume ratio of isopropanol to water in the isopropanol solution is 2:5, the immersion time is 3 minutes, and the ultrasonic frequency is 30KHz.

[0085] S4. After rinsing the silicon carbide substrate and ceramic disk with high-pressure water and drying them, place them on the wafer unloader for wafer unloading. The unloading temperature is 30℃ and the unloading speed is 3 wafers / min. Remove the silicon carbide wafer and place it into the cassette.

[0086] S5, the cartridge containing the silicon carbide substrate is immersed in isopropanol. During the ultrasonic immersion process, the silicon carbide substrate I is rotated around the central axis once every 3 minutes, and the rotation angle is 90° each time. The isopropanol is placed in a quartz measuring cup, and the quartz measuring cup is ultrasonically heated in a water bath at a temperature of 50°C for 12 minutes and an ultrasonic frequency of 60KHz.

[0087] S6. After the silicon carbide substrate is cleaned by ultrapure water frequency conversion ultrasonic cleaning, it is immersed in a mixed solution of dewaxing water and water for up-and-down ultrasonic immersion. The volume ratio of dewaxing water to water is 1:20, the immersion time is 10 min, the immersion temperature is 55℃, the ultrasonic frequency is 60KHz, and the up-and-down immersion frequency is 20 times / min.

[0088] S7. After the silicon carbide substrate is cleaned by ultrapure water frequency conversion ultrasonic cleaning, it is immersed in a mixed solution of dewaxing water, hydrogen peroxide and water for up-and-down ultrasonic immersion. The volume ratio of dewaxing water, hydrogen peroxide and water is 1:1:38, the immersion time is 10 min, the immersion temperature is 55℃, the ultrasonic frequency is 40KHz, and the up-and-down immersion frequency is 20 times / min.

[0089] S8. The silicon carbide substrate is cleaned by ultrapure water frequency conversion ultrasonic cleaning to obtain a clean silicon carbide substrate. The ultrasonic frequency is segmented frequency conversion ultrasonic, first ultrasonic at 40KHZ for 2min, then ultrasonic at 60KHz for 5min, and the ultrasonic cycle is repeated twice.

[0090] The conditions for high-pressure water rinsing in steps S3 and S4 are the same as those in step S1; the conditions for ultrapure water frequency conversion ultrasonic cleaning in steps S6 and S7 are the same as those in step S8.

[0091] Comparative Example 1

[0092] This comparative example provides a method for cleaning a silicon carbide substrate, including the following steps:

[0093] S1. The SiC substrate and ceramic disk after chemical mechanical polishing are rinsed with a high-pressure water gun. The water gun rinsing pressure is 2.5MPa, the rinsing time is 4min, and the rinsing method is double-sided rotary rinsing. During rotary rinsing, the angle between the silicon carbide substrate and the horizontal plane is 45° to 90°.

[0094] S2, place the silicon carbide substrate and ceramic disk on the wafer unloader and unload the wafer. The unloading temperature is 80℃ and the unloading speed is 5 wafers / min. Remove the silicon carbide wafer and place it into the cassette.

[0095] S3, the silicon carbide substrate is immersed in a mixed solution of dewaxing solution and water for ultrasonic soaking, wherein the volume ratio of dewaxing solution to water is 1:18, the soaking time is 30 min, the soaking temperature is 80℃, the ultrasonic frequency is 100KHz, and the frequency of up and down shoveling is 30 times / min.

[0096] S4. The silicon carbide substrate is cleaned by ultrapure water frequency conversion ultrasonic cleaning to obtain a clean silicon carbide substrate. The ultrasonic frequency is segmented frequency conversion ultrasonic, first ultrasonic at 35KHZ for 4min, then ultrasonic at 80KHz for 4min, and the ultrasonic cycle is repeated 3 times.

[0097] Comparative Example 2

[0098] This comparative example provides a cleaning method for a silicon carbide substrate, which differs from Example 1 only in that the first isopropanol solution immersion is omitted; otherwise, it is exactly the same, specifically including the following steps:

[0099] S1. The SiC substrate and ceramic disk after chemical mechanical polishing are rinsed with a high-pressure water gun. The water gun rinsing pressure is 2.5MPa, the rinsing time is 4min, and the rinsing method is double-sided rotary rinsing. During rotary rinsing, the angle between the silicon carbide substrate and the horizontal plane is 45° to 90°.

[0100] S2, the rinsed SiC substrate and ceramic disk are vertically immersed in hydrogen peroxide solution for room temperature ultrasonic immersion, wherein the volume ratio of hydrogen peroxide to water in the hydrogen peroxide solution is 1:25, the immersion time is 15 min, and the ultrasonic frequency is 45KHz.

[0101] S3. After rinsing the silicon carbide substrate and ceramic disk with high-pressure water and drying them, place them on the wafer unloader for wafer unloading. The unloading temperature is 35℃ and the unloading speed is 5 wafers / min. Remove the silicon carbide wafer and place it into the cassette.

[0102] S4, the cartridge containing the silicon carbide substrate is immersed in isopropanol. During the ultrasonic immersion process, the silicon carbide substrate I is rotated around the central axis once every 5 minutes, and the rotation angle is 60° each time. The isopropanol is placed in a quartz measuring cup, and the quartz measuring cup is ultrasonically heated in a water bath at a temperature of 55°C for 30 minutes and an ultrasonic frequency of 80KHz.

[0103] S5. After the silicon carbide substrate is cleaned by ultrapure water frequency conversion ultrasonic cleaning, it is immersed in a mixed solution of dewaxing water and water for up-and-down ultrasonic immersion. The volume ratio of dewaxing water to water is 1:18, the immersion time is 15 min, the immersion temperature is 60℃, the ultrasonic frequency is 80KHz, and the up-and-down immersion frequency is 30 times / min.

[0104] S6. After the silicon carbide substrate is cleaned by ultrapure water frequency conversion ultrasonic cleaning, it is immersed in a mixed solution of dewaxing water, hydrogen peroxide and water for up-and-down ultrasonic immersion. The volume ratio of dewaxing water, hydrogen peroxide and water is 1:1:25, the immersion time is 15 min, the immersion temperature is 65℃, the ultrasonic frequency is 50KHz, and the up-and-down immersion frequency is 30 times / min.

[0105] S7. The silicon carbide substrate is cleaned by ultrapure water frequency conversion ultrasonic cleaning to obtain a clean silicon carbide substrate. The ultrasonic frequency is segmented frequency conversion ultrasonic, first ultrasonic at 35KHz for 4min, then ultrasonic at 80KHz for 4min, and the ultrasonic cycle is repeated 3 times.

[0106] The conditions for high-pressure water rinsing in step S3 are the same as those in step S1; the conditions for ultrapure water frequency conversion ultrasonic cleaning in steps S5 and S6 are the same as those in step S8.

[0107] Comparative Example 3

[0108] This comparative example provides a cleaning method for a silicon carbide substrate, which differs from Example 1 only in that the second isopropanol cleaning is omitted; the remaining steps are exactly the same, specifically including the following steps:

[0109] S1. The SiC substrate and ceramic disk after chemical mechanical polishing are rinsed with a high-pressure water gun. The water gun rinsing pressure is 2.5MPa, the rinsing time is 4min, and the rinsing method is double-sided rotary rinsing. During rotary rinsing, the angle between the silicon carbide substrate and the horizontal plane is 45° to 90°.

[0110] S2, the rinsed SiC substrate and ceramic disk are vertically immersed in hydrogen peroxide solution for room temperature ultrasonic immersion, wherein the volume ratio of hydrogen peroxide to water in the hydrogen peroxide solution is 1:25, the immersion time is 15 min, and the ultrasonic frequency is 45KHz.

[0111] S3. After rinsing the silicon carbide substrate and ceramic disk with high-pressure water, immerse them in an isopropanol solution and sonicate them at room temperature. The volume ratio of isopropanol to water in the isopropanol solution is 9:20, the immersion time is 4 min, and the ultrasonic frequency is 45 kHz.

[0112] S4. After rinsing the silicon carbide substrate and ceramic disk with high-pressure water and drying them, place them on the wafer unloader for wafer unloading. The unloading temperature is 35℃ and the unloading speed is 5 wafers / min. Remove the silicon carbide wafer and place it into the cassette.

[0113] S5. After the silicon carbide substrate is cleaned by ultrapure water frequency conversion ultrasonic cleaning, it is immersed in a mixed solution of dewaxing water and water for up-and-down ultrasonic immersion. The volume ratio of dewaxing water to water is 1:18, the immersion time is 15 min, the immersion temperature is 60℃, the ultrasonic frequency is 80KHz, and the up-and-down immersion frequency is 30 times / min.

[0114] S6. After the silicon carbide substrate is cleaned by ultrapure water frequency conversion ultrasonic cleaning, it is immersed in a mixed solution of dewaxing water, hydrogen peroxide and water for up-and-down ultrasonic immersion. The volume ratio of dewaxing water, hydrogen peroxide and water is 1:1:25, the immersion time is 15 min, the immersion temperature is 65℃, the ultrasonic frequency is 50KHz, and the up-and-down immersion frequency is 30 times / min.

[0115] S7. The silicon carbide substrate is cleaned by ultrapure water frequency conversion ultrasonic cleaning to obtain a clean silicon carbide substrate. The ultrasonic frequency is segmented frequency conversion ultrasonic, first ultrasonic at 35KHz for 4min, then ultrasonic at 80KHz for 4min, and the ultrasonic cycle is repeated 3 times.

[0116] The conditions for high-pressure water rinsing in steps S3 and S4 are the same as those in step S1; the conditions for ultrapure water frequency conversion ultrasonic cleaning in steps S5 and S6 are the same as those in step S7.

[0117] Comparative Example 4

[0118] This comparative example provides a cleaning method for a silicon carbide substrate, which differs from Example 1 only in that the second dewaxing cleaning is omitted; otherwise, it is exactly the same, specifically including the following steps:

[0119] S1. The SiC substrate and ceramic disk after chemical mechanical polishing are rinsed with a high-pressure water gun. The water gun rinsing pressure is 2.5MPa, the rinsing time is 4min, and the rinsing method is double-sided rotary rinsing. During rotary rinsing, the angle between the silicon carbide substrate and the horizontal plane is 45° to 90°.

[0120] S2, the rinsed SiC substrate and ceramic disk are vertically immersed in hydrogen peroxide solution for room temperature ultrasonic immersion, wherein the volume ratio of hydrogen peroxide to water in the hydrogen peroxide solution is 1:25, the immersion time is 15 min, and the ultrasonic frequency is 45KHz.

[0121] S3. After rinsing the silicon carbide substrate and ceramic disk with high-pressure water, immerse them in an isopropanol solution and sonicate them at room temperature. The volume ratio of isopropanol to water in the isopropanol solution is 9:20, the immersion time is 4 min, and the ultrasonic frequency is 45 kHz.

[0122] S4. After rinsing the silicon carbide substrate and ceramic disk with high-pressure water and drying them, place them on the wafer unloader for wafer unloading. The unloading temperature is 35℃ and the unloading speed is 5 wafers / min. Remove the silicon carbide wafer and place it into the cassette.

[0123] S5, the cartridge containing the silicon carbide substrate is immersed in isopropanol. During the ultrasonic immersion process, the silicon carbide substrate I is rotated around the central axis once every 5 minutes, and the rotation angle is 60° each time. The isopropanol is placed in a quartz measuring cup, and the quartz measuring cup is ultrasonically heated in a water bath at a temperature of 55°C for 30 minutes and an ultrasonic frequency of 80KHz.

[0124] S6. After the silicon carbide substrate is cleaned by ultrapure water frequency conversion ultrasonic cleaning, it is immersed in a mixed solution of dewaxing water and water for up-and-down ultrasonic immersion. The volume ratio of dewaxing water to water is 1:18, the immersion time is 15 min, the immersion temperature is 60℃, the ultrasonic frequency is 80KHz, and the up-and-down immersion frequency is 30 times / min.

[0125] S7. The silicon carbide substrate is cleaned by ultrapure water frequency conversion ultrasonic cleaning to obtain a clean silicon carbide substrate. The ultrasonic frequency is segmented frequency conversion ultrasonic, first ultrasonic at 35KHz for 4min, then ultrasonic at 80KHz for 4min, and the ultrasonic cycle is repeated 3 times.

[0126] The conditions for high-pressure water rinsing in steps S3 and S4 are the same as those in step S1; the conditions for ultrapure water frequency conversion ultrasonic cleaning in step S6 are the same as those in step S7.

[0127] Comparative Example 5

[0128] This comparative example provides a cleaning method for a silicon carbide substrate. The only difference from Example 1 is that the cleaning solution for the second dewaxing cleaning is replaced with dewaxing water and water. The rest are exactly the same, and the specific steps are as follows:

[0129] S1. The SiC substrate and ceramic disk after chemical mechanical polishing are rinsed with a high-pressure water gun. The water gun rinsing pressure is 2.5MPa, the rinsing time is 4min, and the rinsing method is double-sided rotary rinsing. During rotary rinsing, the angle between the silicon carbide substrate and the horizontal plane is 45° to 90°.

[0130] S2, the rinsed SiC substrate and ceramic disk are vertically immersed in hydrogen peroxide solution for room temperature ultrasonic immersion, wherein the volume ratio of hydrogen peroxide to water in the hydrogen peroxide solution is 1:25, the immersion time is 15 min, and the ultrasonic frequency is 45KHz.

[0131] S3. After rinsing the silicon carbide substrate and ceramic disk with high-pressure water, immerse them in an isopropanol solution and sonicate them at room temperature. The volume ratio of isopropanol to water in the isopropanol solution is 9:20, the immersion time is 4 min, and the ultrasonic frequency is 45 kHz.

[0132] S4. After rinsing the silicon carbide substrate and ceramic disk with high-pressure water and drying them, place them on the wafer unloader for wafer unloading. The unloading temperature is 35℃ and the unloading speed is 5 wafers / min. Remove the silicon carbide wafer and place it into the cassette.

[0133] S5, the cartridge containing the silicon carbide substrate is immersed in isopropanol. During the ultrasonic immersion process, the silicon carbide substrate I is rotated around the central axis once every 5 minutes, and the rotation angle is 60° each time. The isopropanol is placed in a quartz measuring cup, and the quartz measuring cup is ultrasonically heated in a water bath at a temperature of 55°C for 30 minutes and an ultrasonic frequency of 80KHz.

[0134] S6. After the silicon carbide substrate is cleaned by ultrapure water frequency conversion ultrasonic cleaning, it is immersed in a mixed solution of dewaxing water and water for up-and-down ultrasonic immersion. The volume ratio of dewaxing water to water is 1:18, the immersion time is 15 min, the immersion temperature is 60℃, the ultrasonic frequency is 80KHz, and the up-and-down immersion frequency is 30 times / min.

[0135] S7. After the silicon carbide substrate is cleaned by ultrapure water frequency conversion ultrasonic cleaning, it is immersed in a mixed solution of dewaxing water and water for up-and-down ultrasonic immersion. The volume ratio of dewaxing water and hydrogen peroxide to water is 1:18, the immersion time is 15 min, the immersion temperature is 65℃, the ultrasonic frequency is 50KHz, and the up-and-down immersion frequency is 30 times / min.

[0136] S8. The silicon carbide substrate is cleaned by ultrapure water frequency conversion ultrasonic cleaning to obtain a clean silicon carbide substrate. The ultrasonic frequency is segmented frequency conversion ultrasonic, first ultrasonic at 35KHz for 4min, then ultrasonic at 80KHz for 4min, and the ultrasonic cycle is repeated 3 times.

[0137] The conditions for high-pressure water rinsing in steps S3 and S4 are the same as those in step S1; the conditions for ultrapure water frequency conversion ultrasonic cleaning in steps S6 and S7 are the same as those in step S8.

[0138] Comparative Example 6

[0139] This comparative example provides a cleaning method for a silicon carbide substrate, which differs from Example 1 only in that isopropanol immersion is replaced with ethanol immersion. The specific steps are as follows:

[0140] S1. The SiC substrate and ceramic disk after chemical mechanical polishing are rinsed with a high-pressure water gun. The water gun rinsing pressure is 2.5MPa, the rinsing time is 4min, and the rinsing method is double-sided rotary rinsing. During rotary rinsing, the angle between the silicon carbide substrate and the horizontal plane is 45° to 90°.

[0141] S2, the rinsed SiC substrate and ceramic disk are vertically immersed in hydrogen peroxide solution for room temperature ultrasonic immersion, wherein the volume ratio of hydrogen peroxide to water in the hydrogen peroxide solution is 1:25, the immersion time is 15 min, and the ultrasonic frequency is 45KHz.

[0142] S3. After rinsing the silicon carbide substrate and ceramic disk with high-pressure water, they are immersed in an ethanol solution at room temperature using ultrasonic immersion. The volume ratio of ethanol to water in the ethanol solution is 9:20, the immersion time is 4 min, and the ultrasonic frequency is 45 kHz.

[0143] S4. After rinsing the silicon carbide substrate and ceramic disk with high-pressure water and drying them, place them on the wafer unloader for wafer unloading. The unloading temperature is 35℃ and the unloading speed is 5 wafers / min. Remove the silicon carbide wafer and place it into the cassette.

[0144] S5, the cartridge containing the silicon carbide substrate is immersed in ethanol. During the ultrasonic immersion process, the silicon carbide substrate I is rotated around the central axis once every 5 minutes, and the rotation angle is 60° each time. The ethanol is placed in a quartz measuring cup, and the quartz measuring cup is ultrasonically heated in a water bath at a temperature of 55°C for 30 minutes and an ultrasonic frequency of 80KHz.

[0145] S6. After the silicon carbide substrate is cleaned by ultrapure water frequency conversion ultrasonic cleaning, it is immersed in a mixed solution of dewaxing water and water for up-and-down ultrasonic immersion. The volume ratio of dewaxing water to water is 1:18, the immersion time is 15 min, the immersion temperature is 60℃, the ultrasonic frequency is 80KHz, and the up-and-down immersion frequency is 30 times / min.

[0146] S7. After the silicon carbide substrate is cleaned by ultrapure water frequency conversion ultrasonic cleaning, it is immersed in a mixed solution of dewaxing water, hydrogen peroxide and water for up-and-down ultrasonic immersion. The volume ratio of dewaxing water, hydrogen peroxide and water is 1:1:25, the immersion time is 15 min, the immersion temperature is 65℃, the ultrasonic frequency is 50KHz, and the up-and-down immersion frequency is 30 times / min.

[0147] S8. The silicon carbide substrate is cleaned by ultrapure water frequency conversion ultrasonic cleaning to obtain a clean silicon carbide substrate. The ultrasonic frequency is segmented frequency conversion ultrasonic, first ultrasonic at 35KHz for 4min, then ultrasonic at 80KHz for 4min, and the ultrasonic cycle is repeated 3 times.

[0148] The conditions for high-pressure water rinsing in steps S3 and S4 are the same as those in step S1; the conditions for ultrapure water frequency conversion ultrasonic cleaning in steps S6 and S7 are the same as those in step S8.

[0149] Comparative Example 7

[0150] This comparative example provides a cleaning method for silicon carbide substrates, changing the timing of hydrogen peroxide immersion. The specific steps are as follows:

[0151] S1. The SiC substrate and ceramic disk after chemical mechanical polishing are rinsed with a high-pressure water gun. The water gun rinsing pressure is 2.5MPa, the rinsing time is 4min, and the rinsing method is double-sided rotary rinsing. During rotary rinsing, the angle between the silicon carbide substrate and the horizontal plane is 45° to 90°.

[0152] S2, the silicon carbide substrate and ceramic disk are immersed in isopropanol solution at room temperature by ultrasonic immersion. The volume ratio of isopropanol to water in the isopropanol solution is 9:20, the immersion time is 4 min, and the ultrasonic frequency is 45KHz.

[0153] S3. After rinsing the silicon carbide substrate and ceramic disk with high-pressure water and drying them, place them on the wafer unloader for wafer unloading. The unloading temperature is 35℃ and the unloading speed is 5 wafers / min. Remove the silicon carbide wafer and place it into the cassette.

[0154] S4, the cartridge containing the silicon carbide substrate is immersed in isopropanol. During the ultrasonic immersion process, the silicon carbide substrate I is rotated around the central axis once every 5 minutes, and the rotation angle is 60° each time. The isopropanol is placed in a quartz measuring cup, and the quartz measuring cup is ultrasonically heated in a water bath at a temperature of 55°C for 30 minutes and an ultrasonic frequency of 80KHz.

[0155] S5. After the silicon carbide substrate is cleaned by frequency conversion ultrasonic cleaning with ultrapure water, it is immersed in hydrogen peroxide solution for room temperature ultrasonic soaking. The volume ratio of hydrogen peroxide to water in the hydrogen peroxide solution is 1:25, the soaking time is 15 min, and the ultrasonic frequency is 45KHz.

[0156] S6. After the silicon carbide substrate is cleaned by ultrapure water frequency conversion ultrasonic cleaning, it is immersed in a mixed solution of dewaxing water and water for up-and-down ultrasonic immersion. The volume ratio of dewaxing water to water is 1:18, the immersion time is 15 min, the immersion temperature is 60℃, the ultrasonic frequency is 80KHz, and the up-and-down immersion frequency is 30 times / min.

[0157] S7. After the silicon carbide substrate is cleaned by ultrapure water frequency conversion ultrasonic cleaning, it is immersed in a mixed solution of dewaxing water, hydrogen peroxide and water for up-and-down ultrasonic immersion. The volume ratio of dewaxing water, hydrogen peroxide and water is 1:1:25, the immersion time is 15 min, the immersion temperature is 65℃, the ultrasonic frequency is 50KHz, and the up-and-down immersion frequency is 30 times / min.

[0158] S8. The silicon carbide substrate is cleaned by ultrapure water frequency conversion ultrasonic cleaning to obtain a clean silicon carbide substrate. The ultrasonic frequency is segmented frequency conversion ultrasonic, first ultrasonic at 35KHz for 4min, then ultrasonic at 80KHz for 4min, and the ultrasonic cycle is repeated 3 times.

[0159] The conditions for high-pressure water rinsing in step S3 are the same as those in step S1; the conditions for ultrapure water frequency conversion ultrasonic cleaning in steps S5-S7 are the same as those in step S8.

[0160] The silicon carbide substrates obtained from the cleaning processes described in the above examples and comparative examples were subjected to the same RCA cleaning. The RCA cleaning process includes SPM, SC1, SC2, and HF cleaning processes.

[0161] The cleaning solution in the SPM process is a mixed solution of sulfuric acid (98%) and hydrogen peroxide with a volume ratio of 17:3. The cleaning time is 15 minutes and the cleaning temperature is 120°C.

[0162] The cleaning solution for the SC1 process is a mixed solution of ammonia (28%), hydrogen peroxide and water in a volume ratio of 1:2:7. The cleaning time is 10 minutes and the cleaning temperature is 70°C.

[0163] The cleaning solution for the SC2 process is a mixture of hydrochloric acid (37%), hydrogen peroxide, and water in a volume ratio of 1:1:5. The cleaning time is 10 minutes and the cleaning temperature is 70°C.

[0164] The cleaning solution for the HF cleaning process is a mixture of hydrofluoric acid (49%) and water at a volume ratio of 1:99. The cleaning time is 5 minutes and the cleaning temperature is room temperature.

[0165] After the above dewaxing and cleaning of Examples 1-3 and Comparative Examples 1-7 were completed, the presence of residual wax on the SiC substrate was observed using a high-intensity halogen lamp. The results are shown in Table 1.

[0166] Table 1

[0167] describe Wax residue Example 1 No residue Example 2 No residue Example 3 No residue Comparative Example 1 More residue Comparative Example 2 Residue Comparative Example 3 Residue Comparative Example 4 Residue Comparative Example 5 none Comparative Example 6 Residue Comparative Example 7 none

[0168] After the RCA cleaning of Examples 1-3 and Comparative Examples 1-7 were completed as described above, particle residue on the SiC substrate surface was tested using a Candela 8520. The results are shown in Table 2 and... Figures 1-10 As shown.

[0169] Table 2

[0170] describe Particle count Particle aggregation Example 1 2 none Example 2 3 none Example 3 5 none Comparative Example 1 191 yes Comparative Example 2 45 yes Comparative Example 3 67 yes Comparative Example 4 46 yes Comparative Example 5 29 none Comparative Example 6 98 yes Comparative Example 7 88 yes

[0171] Cleaning ability evaluation

[0172] Two hundred SiC substrates after chemical mechanical polishing were cleaned using the processes described in Examples 1-3 and Comparative Examples 1-7, respectively. The degree of contamination of the dewaxing solution after cleaning was observed for each of the 200 substrates. A continuous cleaning test was also conducted to measure the total number of SiC substrates cleaned when the cleaning solution became contaminated. The results are shown in Table 3.

[0173] Table 3

[0174]

[0175]

[0176] Note: The criterion for judging the turbidity of the cleaning solution is that the presence of wax residue floating on the surface of the cleaning solution is considered as turbidity.

[0177] Wax remover 1 is a mixture of wax remover and water, while wax remover 2 is a mixture of wax remover, hydrogen peroxide, and water.

[0178] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions or improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A cleaning method of a silicon carbide substrate, characterized by, The silicon carbide substrate is a silicon carbide substrate adhered to a ceramic disc after chemical mechanical polishing, and the cleaning method comprises the following steps: S1, the silicon carbide substrate to be cleaned is washed by high pressure water, and the washed silicon carbide substrate is sequentially immersed in hydrogen peroxide solution and isopropanol solution, then is placed, the silicon carbide substrate is separated from the ceramic disc, and the silicon carbide substrate I is obtained; the placing temperature is 30-40 DEG C; the isopropanol solution is a mixed solution of isopropanol and water with a volume ratio of 1:2-2:5; S2, the silicon carbide substrate I is placed in isopropanol, heated, and ultrasonically immersed to obtain the silicon carbide substrate II; S3, the silicon carbide substrate II is placed in a mixed solution of de-waxing water and water, heated, and ultrasonically immersed to obtain the silicon carbide substrate III; S4, the silicon carbide substrate III is placed in a mixed solution of de-waxing water, hydrogen peroxide and water, heated, and ultrasonically immersed to obtain the clean silicon carbide substrate.

2. The method of cleaning a silicon carbide substrate of claim 1, wherein, In step S1, the washing pressure of the high pressure water washing is 2-3 MPa, the washing time is 3-6 min, the washing mode is double-sided rotary washing, and the included angle between the silicon carbide substrate and the horizontal plane during rotary washing is 45-90 DEG; and / or In step S1, the hydrogen peroxide solution is a mixed solution of hydrogen peroxide and water with a volume ratio of 1:20-1:30; and / or In step S1, the ultrasonic immersion power of the hydrogen peroxide solution is 30-60 KHz, and the ultrasonic immersion time is 10-20 min.

3. The method of cleaning a silicon carbide substrate of claim 1, wherein, In step S1, the ultrasonic immersion power of the isopropanol solution is 30-60 KHz, and the ultrasonic immersion time is 3-5 min.

4. The method of cleaning a silicon carbide substrate of claim 1, wherein, In step S2, the ultrasonic immersion power is 60-100 KHz, the ultrasonic immersion time is 12-36 min, and the ultrasonic immersion temperature is 50-60 DEG C.

5. The method of cleaning a silicon carbide substrate according to claim 1 or 4, wherein In step S2, during the ultrasonic immersion, the silicon carbide substrate I is rotated around the central axis by 60-90 DEG every 3-6 min.

6. The method of cleaning a silicon carbide substrate of claim 1, wherein, In step S3, the de-waxing water comprises the following components in mass percentage: fatty alcohol polyoxyethylene ether 5-15%, alkanolamide polyoxyethylene ether 5-15%, dimethicone 3-10%, polyethylene glycol 2-10%, stearic acid 3-10%, and the balance is deionized water.

7. The method of cleaning a silicon carbide substrate according to claim 1 or 6, wherein In step S3, the volume ratio of the de-waxing water to deionized water is 1:15-1:20; and / or In step S3, the ultrasonic immersion power is 60-100 KHz, the ultrasonic immersion time is 10-20 min, and the ultrasonic immersion temperature is 55-70 DEG C; and / or In step S3, the silicon carbide substrate II is thrown up and down while being ultrasonically immersed, and the throwing frequency is 20-40 times / min.

8. The method of cleaning a silicon carbide substrate of claim 1, wherein, In step S4, the de-waxing water comprises the following components in mass percentage: fatty alcohol polyoxyethylene ether 5-15%, alkanolamide polyoxyethylene ether 5-15%, dimethicone 3-10%, polyethylene glycol 2-10%, stearic acid 3-10%, and the balance is deionized water.

9. The cleaning method of silicon carbide substrate according to claim 1 or 8, wherein In step S4, the volume ratio of the de-waxing water, hydrogen peroxide and deionized water is 1:1:18-1:1:38; and / or In step S4, the power of the ultrasonic immersion is 40-60 KHz, the time of the ultrasonic immersion is 10-20 min, and the temperature of the ultrasonic immersion is 55-70℃; and / or In step S4, the silicon carbide substrate III is thrown up and down while being subjected to the ultrasonic immersion, and the frequency of the throwing is 20-40 times / min.

10. The method of cleaning a silicon carbide substrate of claim 1, wherein, In steps S2-S4, after each cleaning, frequency conversion ultrasonic cleaning with ultrapure water is required, and the specific process of the frequency conversion ultrasonic cleaning is as follows: first ultrasonic at 30-40 KHz for 2-5 min, and then ultrasonic at 60-100 KHz for 3-5 min, and the above steps are repeated for 2-4 times.

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