A pre-cleaning method for silicon carbide substrate before leakage detection

Abstract

The present invention relates to the field of semiconductor manufacturing technology, and specifically discloses a pre-cleaning method for detecting liquid leakage of a silicon carbide substrate. The present invention advances the pre-cleaning method to the silicon carbide substrate process, firstly uses pure water ultrasonic cleaning to remove large particles of grinding liquid attached to the surface of the silicon carbide substrate, then performs multi-band ultrasonic cleaning in a hydrofluoric acid / sulfuric acid mixed acid solution to effectively remove impurities accumulated in tiny pipes, and finally soaks in a sodium bicarbonate aqueous solution to remove oil stains on the surface of the silicon carbide substrate, thereby achieving effective removal of impurities on the surface of the silicon carbide substrate, especially in pipe defects below 2 microns, thereby effectively improving the full detection of silicon carbide substrate leakage points, reducing the waste of processing costs of leaking substrates, and improving the production efficiency of silicon carbide substrates, which is of great significance for improving the qualified rate of epitaxial devices and has a high value of popularization and application.

Description

Technical Field

[0001] The invention relates to the technical field of semiconductor manufacturing, and in particular to a pre-cleaning method for silicon carbide substrate leakage detection. Background Art

[0002] With the continuous development of China's semiconductor manufacturing industry, SiC, as a third-generation semiconductor material, has been widely used in industrial fields such as metallurgy, chemical industry, and semiconductor manufacturing. The presence of leaks in silicon carbide substrates will seriously affect epitaxy, and in severe cases will cause device failure. The defects that cause silicon carbide leakage include hollow pipe defects and cracks, with sizes ranging from hundreds of nanometers to tens of microns, or even thousands of microns. During the processing of silicon carbide substrates, abrasives / abrasive fluids accumulate in the pipes. If they are not properly cleaned before leak detection, the accuracy of the leakage detection process will be seriously affected, and it may even lead to the inability to detect leaks, thereby causing immeasurable losses to epitaxial devices.

[0003] Usually, the cobalt carbide substrate needs to go through multiple processing and testing from the ingot to the finished product, generally including cutting, grinding, multi-step polishing, testing, cleaning, epitaxy and other processes. Cutting is usually steel wire cutting, and the surface of the silicon carbide substrate is prone to residual line marks or saw marks after cutting. The line marks or saw marks are removed by grinding later, and at the same time, the roughness of the substrate surface is reduced. After multi-step polishing, the surface roughness of the substrate is further reduced to meet the requirements of epitaxy. At present, leakage detection is usually carried out after polishing. The leakage substrate detected after polishing undoubtedly increases the processing cost of the polishing section, and the current cleaning method is usually ultrasonic cleaning in alcohol or dewaxing water, mainly removing the polishing liquid (diamond powder, aluminum oxide, oxidant, etc.) adhering to the surface of the silicon carbide substrate. This method only has a good effect on the cleaning of stains and large-size defects on the surface of the silicon carbide substrate. However, the impurities in the pipeline defects within 2 microns in the silicon carbide substrate cannot be effectively cleaned and removed, resulting in the inability to fully detect the leakage points in the silicon carbide substrate in the future. Summary of the invention

[0004] In view of the problem that the cleaning method before the silicon carbide substrate leakage detection in the prior art cannot fully remove the impurities in the pipeline defects within 2 microns in the silicon carbide substrate, thereby affecting the detection accuracy, the present invention provides a pre-cleaning method for silicon carbide substrate leakage detection. The present invention advances the cleaning process to after the substrate is ground, and sequentially subjects the ground silicon carbide substrate to ultrasonic water cleaning, multi-band ultrasonic cleaning in hydrofluoric acid / sulfuric acid mixed acid, and alkaline cleaning processes, thereby completely removing the dirt in the micro-sized pipeline defects, thereby significantly improving the accuracy of subsequent leakage detection, reducing the waste of processing costs of the leaking substrate, and having a high value for promotion and application.

[0005] In order to solve the above technical problems, the technical solution provided by the present invention is:

[0006] A pre-cleaning method for silicon carbide substrate leakage detection is performed after the silicon carbide substrate cutting and grinding process. The pre-cleaning method comprises the following steps:

[0007] S1, ultrasonically cleaning the silicon carbide polishing sheet in pure water, wiping the surface, and obtaining a silicon carbide substrate 1;

[0008] S2, performing multi-band ultrasonic cleaning on the silicon carbide substrate I in a mixed acid solution of hydrofluoric acid and sulfuric acid, and bubbling water washing to obtain a silicon carbide substrate II;

[0009] S3, placing the silicon carbide substrate II in a sodium bicarbonate aqueous solution, soaking, bubbling water washing, and drying to obtain a clean silicon carbide substrate.

[0010] Compared with the prior art, the pre-cleaning method for silicon carbide substrate leakage detection provided by the present invention advances the pre-cleaning method to the silicon carbide substrate process, firstly uses pure water ultrasonic cleaning to remove large particles of grinding liquid attached to the surface of the silicon carbide substrate, then multi-band ultrasonic cleaning is performed in a hydrofluoric acid / sulfuric acid mixed acid solution to effectively remove impurities accumulated in tiny pipes, and finally the silicon carbide substrate is immersed in a sodium bicarbonate aqueous solution to remove oil stains on the surface, thereby achieving effective removal of impurities on the surface of the silicon carbide substrate, especially in pipe defects below 2 microns, thereby effectively improving the full detection of silicon carbide substrate leakage points, reducing the waste of processing costs of leaking substrates, and effectively reducing production energy consumption and costs, and having a high value for promotion and application.

[0011] The present invention reduces the waste of processing cost of the leaking substrate by making an early judgment on the leaking substrate, improves the production efficiency of the silicon carbide substrate, and is of great significance for improving the qualified rate of epitaxial devices.

[0012] It should be noted that after adopting the above-mentioned cleaning process of this scheme, the next step of leakage detection can be carried out. After the leakage detection is passed, polishing, cleaning, epitaxial growth and other processes are carried out.

[0013] Furthermore, in S1, the temperature of the ultrasonic cleaning is 40°C to 70°C, the ultrasonic power is 40KHz to 50KHz, and the ultrasonic time is 2min to 10min.

[0014] The preferred ultrasonic cleaning conditions can fully remove the grinding liquid particles on the surface of the silicon carbide substrate.

[0015] Specifically, in S1, the surface of the silicon carbide substrate after ultrasonic washing is wiped with dust-free paper to remove large particles remaining on the surface of the silicon carbide substrate. The wiping time is 3s to 30s, and a piece of dust-free paper is replaced every time 3 to 5 silicon carbide substrates are wiped.

[0016] Furthermore, in S2, the specific steps of the multi-band ultrasonic cleaning are: firstly ultrasonically cleaning at 110KHz to 130KHz for a first preset time, and then ultrasonically cleaning at 160KHz to 170KHz for a second preset time.

[0017] In combination with the above, further, in S2, the first preset time is 5 minutes to 10 minutes.

[0018] In combination with the above, further, in S2, the second preset time is 5 minutes to 10 minutes.

[0019] The preferred multi-band ultrasonic method can not only fully remove impurities in pipeline defects with a size of less than 2 microns, but also help to improve cleaning efficiency and reduce cleaning energy consumption.

[0020] Furthermore, in S2, the specific steps of the multi-band ultrasonic cleaning are: first, ultrasonic cleaning at 40KHz to 50KHz for the third preset time, ultrasonic cleaning at 70KHz to 90KHz for the fourth preset time, ultrasonic cleaning at 110KHz to 130KHz for the fifth preset time, and finally ultrasonic cleaning at 160KHz to 170KHz for the sixth preset time.

[0021] Specifically, in S2, the third preset time is 2 minutes to 5 minutes.

[0022] Specifically, in S2, the fourth preset time is 2 minutes to 5 minutes.

[0023] Specifically, in S2, the fifth preset time is 5 minutes to 10 minutes.

[0024] Specifically, in S2, the sixth preset time is 5 minutes to 10 minutes.

[0025] The preferred multi-band ultrasonic method can fully remove impurities in pipeline defects with a size of less than 2 microns and improve the accuracy of leak point detection.

[0026] Furthermore, in S2, the volume ratio of the hydrofluoric acid to the sulfuric acid is 4:1 to 1:1, wherein the mass concentration of the hydrofluoric acid is 40% to 55%, and the concentration of the sulfuric acid is 95% to 98%.

[0027] Furthermore, in S2, the bubbling time of the bubbling water washing is 30s to 60s, and the overflow time is 5min to 15min.

[0028] Furthermore, in S3, the soaking temperature is 40°C to 60°C, and the soaking time is 5 min to 10 min.

[0029] Furthermore, in S3, the bubbling time of the bubbling water washing is 30s to 60s, and the overflow time is 5min to 15min.

[0030] Furthermore, in S3, the volume ratio of the sodium bicarbonate to water is 1:19 to 1:9.

[0031] Furthermore, in S3, a spin dryer is used to dry the cleaned silicon carbide substrate, the rotation speed of the spin dryer is 600 r / min to 1200 r / min, and the spin drying time is 5 min to 8 min.

[0032] The cleaning method of the silicon carbide substrate provided by the present invention performs layer-by-layer peeling according to the distribution of residues on the surface of the silicon carbide substrate after grinding, and achieves complete removal of residues on the surface of the silicon carbide substrate without destroying the internal structure of the silicon carbide substrate, thereby effectively improving the accuracy of leak point detection and avoiding the waste of processing costs of leaking silicon carbide substrates. It is of great significance for improving the qualified rate of epitaxial devices, is suitable for industrial production applications, has significant economic and environmental benefits, and has broad application prospects. DETAILED DESCRIPTION

[0033] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0034] In order to better illustrate the present invention, further examples are given below.

[0035] The sulfuric acid used in the following examples and comparative examples is commercially available concentrated sulfuric acid with a mass fraction of 98%; the hydrofluoric acid used is commercially available hydrofluoric acid with a mass fraction of 40%.

[0036] The cleaned silicon carbide substrate is a silicon carbide polishing sheet that has been processed into a double-sided polished state after cutting.

[0037] Example 1

[0038] This embodiment provides a pre-cleaning method for silicon carbide substrate before liquid leakage detection, comprising the following steps:

[0039] S1, ultrasonically clean the silicon carbide polishing sheet in 60°C pure water for 5 min at an ultrasonic frequency of 45KHz;

[0040] S2, wiping the silicon carbide substrate after ultrasonic cleaning with dust-free paper for 15 seconds, replacing a piece of dust-free paper every 4 sheets;

[0041] S3, after the wiping is completed, the silicon carbide substrate is transferred into a mixed acid solution of hydrofluoric acid / sulfuric acid, the volume ratio of hydrofluoric acid to sulfuric acid is 2:1, and ultrasonically treated at an ultrasonic frequency of 120 KHz for 12 minutes, and then ultrasonically treated at an ultrasonic frequency of 165 KHz for 12 minutes;

[0042] S4, after acid ultrasonic cleaning, transfer to a water tank with bubbling, fast drain and overflow for cleaning, with a bubbling time of 50 seconds and an overflow time of 10 minutes;

[0043] S5, after the water tank cleaning is completed, the silicon carbide substrate is immersed in a sodium bicarbonate aqueous solution, the volume ratio of sodium bicarbonate to water is 1:15, the immersion temperature is 50° C., and the immersion time is 8 minutes;

[0044] S6, after the alkaline washing is completed, it is transferred to a water tank with bubbling, quick discharge and overflow for washing, the bubbling time is 40s, and the overflow time is 10min;

[0045] S7, transferring the silicon carbide substrate into a spin dryer at a rotation speed of 1000 r / min for 6 minutes, and performing a liquid leakage test on the cleaned silicon carbide substrate.

[0046] Example 2

[0047] This embodiment provides a pre-cleaning method for silicon carbide substrate before liquid leakage detection, comprising the following steps:

[0048] S1, ultrasonically clean the silicon carbide polishing sheet in 40°C pure water for 10 min at an ultrasonic frequency of 40 KHz;

[0049] S2, wiping the silicon carbide substrate after ultrasonic cleaning with dust-free paper for 3 seconds, replacing a piece of dust-free paper every 5 sheets;

[0050] S3, after the wiping is completed, the silicon carbide substrate is transferred into a mixed acid solution of hydrofluoric acid / sulfuric acid, the volume ratio of hydrofluoric acid to sulfuric acid is 4:1, and ultrasonically treated at an ultrasonic frequency of 130 KHz for 10 minutes, and then ultrasonically treated at an ultrasonic frequency of 170 KHz for 10 minutes;

[0051] S4, after acid ultrasonic cleaning, transfer to a water tank with bubbling, fast drain and overflow for cleaning, with a bubbling time of 30 seconds and an overflow time of 15 minutes;

[0052] S5, after the water tank cleaning is completed, the silicon carbide substrate is immersed in a sodium bicarbonate aqueous solution, the volume ratio of sodium bicarbonate to water is 1:19, the immersion temperature is 60° C., and the immersion time is 5 min;

[0053] S6, after the alkaline washing is completed, the water is transferred to a water tank with bubbling, quick discharge and overflow for washing, the bubbling time is 60s, and the overflow time is 5min;

[0054] S7, transferring the silicon carbide substrate into a spin dryer at a rotation speed of 600 r / min for 8 minutes, and performing a liquid leakage test on the cleaned silicon carbide substrate.

[0055] Example 3

[0056] This embodiment provides a pre-cleaning method for silicon carbide substrate before liquid leakage detection, comprising the following steps:

[0057] S1, ultrasonically clean the silicon carbide polishing sheet in 70°C pure water for 2 min at an ultrasonic frequency of 50 KHz;

[0058] S2, wiping the silicon carbide substrate after ultrasonic cleaning with dust-free paper for 30 seconds, replacing a piece of dust-free paper every three sheets;

[0059] S3, after the wiping is completed, the silicon carbide substrate is transferred into a mixed acid solution of hydrofluoric acid / sulfuric acid, the volume ratio of hydrofluoric acid to sulfuric acid is 1:1, and ultrasonically treated at an ultrasonic frequency of 110 KHz for 15 minutes, and then ultrasonically treated at an ultrasonic frequency of 160 KHz for 15 minutes;

[0060] S4, after acid ultrasonic cleaning, transfer to a water tank with bubbling, fast drain and overflow for cleaning, with a bubbling time of 60 seconds and an overflow time of 5 minutes;

[0061] S5, after the water tank cleaning is completed, the silicon carbide substrate is immersed in a sodium bicarbonate aqueous solution, the volume ratio of sodium bicarbonate to water is 1:9, the immersion temperature is 40° C., and the immersion time is 10 min;

[0062] S6, after the alkaline washing is completed, the water is transferred to a water tank with bubbling, quick discharge and overflow for washing, the bubbling time is 30s, and the overflow time is 15min;

[0063] S7, transfer the silicon carbide substrate into a spin dryer at a rotation speed of 1200 r / min for 5 minutes, and perform a liquid leakage test on the cleaned silicon carbide substrate.

[0064] Example 4

[0065] This embodiment provides a pre-cleaning method for silicon carbide substrate before liquid leakage detection, comprising the following steps:

[0066] S1, ultrasonically clean the silicon carbide polishing sheet in 60°C pure water for 5 min at an ultrasonic frequency of 45KHz;

[0067] S2, wiping the silicon carbide substrate after ultrasonic cleaning with dust-free paper for 15 seconds, replacing a piece of dust-free paper every 4 sheets;

[0068] S3, after the wiping is completed, the silicon carbide substrate is transferred to a mixed acid solution of hydrofluoric acid / sulfuric acid, the volume ratio of hydrofluoric acid to sulfuric acid is 2:1, firstly ultrasonically treated at an ultrasonic frequency of 45KHz for 4 minutes, then ultrasonically treated at an ultrasonic frequency of 80KHz for 4 minutes, then ultrasonically treated at 120KHz for 8 minutes, and finally ultrasonically treated at 165KHz for 8 minutes;

[0069] S4, after acid ultrasonic cleaning, transfer to a water tank with bubbling, fast drain and overflow for cleaning, with a bubbling time of 50 seconds and an overflow time of 10 minutes;

[0070] S5, after the water tank cleaning is completed, the silicon carbide substrate is immersed in a sodium bicarbonate aqueous solution, the volume ratio of sodium bicarbonate to water is 1:15, the immersion temperature is 50° C., and the immersion time is 8 minutes;

[0071] S6, after the alkaline washing is completed, it is transferred to a water tank with bubbling, quick discharge and overflow for washing, the bubbling time is 40s, and the overflow time is 10min;

[0072] S7, transferring the silicon carbide substrate into a spin dryer at a rotation speed of 1000 r / min for 6 minutes, and performing a liquid leakage test on the cleaned silicon carbide substrate.

[0073] Example 5

[0074] This embodiment provides a pre-cleaning method for silicon carbide substrate before liquid leakage detection, comprising the following steps:

[0075] S1, ultrasonically clean the silicon carbide polishing sheet in 60°C pure water for 5 min at an ultrasonic frequency of 45KHz;

[0076] S2, wiping the silicon carbide substrate after ultrasonic cleaning with dust-free paper for 15 seconds, replacing a piece of dust-free paper every 4 sheets;

[0077] S3, after the wiping is completed, the silicon carbide substrate is transferred to a mixed acid solution of hydrofluoric acid / sulfuric acid, the volume ratio of hydrofluoric acid to sulfuric acid is 2:1, firstly ultrasonically treated at 165KHz for 8 minutes, then ultrasonically treated at 120KHz for 8 minutes, then ultrasonically treated at an ultrasonic frequency of 80KHz for 4 minutes, and finally ultrasonically treated at an ultrasonic frequency of 45KHz for 4 minutes;

[0078] S4, after acid ultrasonic cleaning, transfer to a water tank with bubbling, fast drain and overflow for cleaning, with a bubbling time of 50 seconds and an overflow time of 10 minutes;

[0079] S5, after the water tank cleaning is completed, the silicon carbide substrate is immersed in a sodium bicarbonate aqueous solution, the volume ratio of sodium bicarbonate to water is 1:15, the immersion temperature is 50° C., and the immersion time is 8 minutes;

[0080] S6, after the alkaline washing is completed, it is transferred to a water tank with bubbling, quick discharge and overflow for washing, the bubbling time is 40s, and the overflow time is 10min;

[0081] S7, transferring the silicon carbide substrate into a spin dryer at a rotation speed of 1000 r / min for 6 minutes, and performing a liquid leakage test on the cleaned silicon carbide substrate.

[0082] Example 6

[0083] This embodiment provides a pre-cleaning method for silicon carbide substrate leakage detection. The specific steps are the same as those in Embodiment 1, except that the pre-cleaning step is performed after the polishing process. The specific steps are as follows:

[0084] S1, ultrasonically clean the silicon carbide polishing sheet in 60°C pure water for 5 min at an ultrasonic frequency of 45KHz;

[0085] S2, wiping the silicon carbide substrate after ultrasonic cleaning with dust-free paper for 15 seconds, replacing a piece of dust-free paper every 4 sheets;

[0086] S3, after the wiping is completed, the silicon carbide substrate is placed in dewaxing water with a mass concentration of 8%, and ultrasonically treated for 12 minutes at an ultrasonic frequency of 120 KHz, and then ultrasonically treated for 12 minutes at an ultrasonic frequency of 165 KHz;

[0087] S4, transfer to a water tank with bubbling, quick drain and overflow for cleaning, with a bubbling time of 50 seconds and an overflow time of 10 minutes;

[0088] S5, after the water tank cleaning is completed, the silicon carbide substrate is immersed in a sodium bicarbonate aqueous solution, the volume ratio of sodium bicarbonate to water is 1:15, the immersion temperature is 50° C., and the immersion time is 8 minutes;

[0089] S6, after the alkaline washing is completed, it is transferred to a water tank with bubbling, quick discharge and overflow for washing, the bubbling time is 40s, and the overflow time is 10min;

[0090] S7, transferring the silicon carbide substrate into a spin dryer at a rotation speed of 1000 r / min for 6 minutes, and performing a liquid leakage test on the cleaned silicon carbide substrate.

[0091] Comparative Example 1

[0092] This comparative example provides a pre-cleaning method for silicon carbide substrate before leakage detection, comprising the following steps:

[0093] The ground silicon carbide substrate was placed in pure water and ultrasonically cleaned at 50° C. and 40 kHz for 10 min. The cleaned silicon carbide substrate was tested for liquid leakage.

[0094] Comparative Example 2

[0095] This comparative example provides a pre-cleaning method for silicon carbide substrate before leakage detection, comprising the following steps:

[0096] The polished silicon carbide substrate was placed in dewaxed water with a mass concentration of 8%, and ultrasonically cleaned at 50° C. and 40 kHz for 15 minutes. The cleaned silicon carbide substrate was tested for liquid leakage.

[0097] Comparative Example 3

[0098] This comparative example provides a pre-cleaning method for silicon carbide substrate before leakage detection, comprising the following steps:

[0099] The cut silicon carbide substrate was placed in a degreasing cleaning agent (FKD-835D), ultrasonically cleaned at 50°C and 40KHz for 15 minutes, and then transferred to a water tank with bubbling, fast drain and overflow for cleaning; the cleaning was repeated twice according to the above method, and leakage detection was performed.

[0100] Leakage detection

[0101] 20 silicon carbide substrates were randomly selected and cleaned according to Examples 1 to 6 and Comparative Examples 1 to 3, and then tested for liquid leakage. The results are shown in Table 1.

[0102] The sampling method of 20 silicon carbide substrates in each group is:

[0103] After multiple ingots are selected and cut, single-numbered wafers are selected for processing and a leakage test is performed after polishing. Double-numbered wafers in the ingots with single-numbered wafers leaking are selected as verified silicon carbide substrates with leakage, and 3 wafers are placed in each group of embodiments; and single-numbered wafers without leakage are selected as verified silicon carbide substrates without leakage, and 17 wafers are placed in each group of embodiments. That is, 3 silicon carbide substrates with leakage are included in each group of 20 silicon carbide substrates.

[0104] Table 1 Number of detected leaking silicon carbide substrates

[0105] Group Leakage quantity Example 1 3 Example 2 3 Example 3 3 Example 4 3 Example 5 2 Example 6 3 Comparative Example 1 1 Comparative Example 2 2 Comparative Example 3 15

[0106] The results show that the cleaning method of this scheme can achieve the same leakage detection effect as cleaning after polishing by cleaning after grinding, and the detection amount of leaking silicon carbide substrate is higher than the effect of conventional water cleaning (Comparative Example 1) and dewaxing water cleaning (Comparative Example 2). The leakage detection after cutting is unreliable due to the influence of line marks / saw marks on the silicon carbide surface.

[0107] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modification, equivalent substitution or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A pre-cleaning method for silicon carbide substrate leakage detection, characterized in that: Pre-cleaning is performed after the silicon carbide substrate cutting and grinding process, and the pre-cleaning method includes the following steps: S1, ultrasonically cleaning the silicon carbide polishing sheet in pure water, wiping the surface, and obtaining a silicon carbide substrate 1; S2, subjecting the silicon carbide substrate I to multi-band ultrasonic cleaning in a mixed acid solution of hydrofluoric acid and sulfuric acid, and bubbling water washing to obtain a silicon carbide substrate II; the volume ratio of the hydrofluoric acid to the sulfuric acid is 4:1 to 1:1, wherein the mass concentration of the hydrofluoric acid is 40% to 55%, and the concentration of the sulfuric acid is 95% to 98%; S3, placing the silicon carbide substrate II in a sodium bicarbonate aqueous solution, soaking, bubbling water washing, and drying to obtain a clean silicon carbide substrate.

2. The pre-cleaning method for silicon carbide substrate leakage detection according to claim 1, characterized in that: In S1, the temperature of the ultrasonic cleaning is 40°C to 70°C, the ultrasonic power is 40KHz to 50KHz, and the ultrasonic time is 2min to 10min.

3. The pre-cleaning method for silicon carbide substrate leakage detection according to claim 1, characterized in that: In S2, the specific steps of the multi-band ultrasonic cleaning are: firstly ultrasonically cleaning at 110KHz to 130KHz for a first preset time, and then ultrasonically cleaning at 160KHz to 170KHz for a second preset time.

4. The pre-cleaning method for silicon carbide substrate leakage detection according to claim 3, characterized in that: In S2, the first preset time is 5 minutes to 10 minutes; and / or In S2, the second preset time is 5 minutes to 10 minutes.

5. The pre-cleaning method for silicon carbide substrate leakage detection according to claim 1, characterized in that: In S2, the specific steps of the multi-band ultrasonic cleaning are: first, ultrasonic cleaning at 40KHz to 50KHz for the third preset time, ultrasonic cleaning at 70KHz to 90KHz for the fourth preset time, ultrasonic cleaning at 110KHz to 130KHz for the fifth preset time, and finally ultrasonic cleaning at 160KHz to 170KHz for the sixth preset time.

6. The pre-cleaning method for silicon carbide substrate leakage detection according to claim 5, characterized in that: In S2, the third preset time is 2 minutes to 5 minutes; and / or In S2, the fourth preset time is 2 minutes to 5 minutes; and / or In S2, the fifth preset time is 5 minutes to 10 minutes; and / or In S2, the sixth preset time is 5 minutes to 10 minutes.

7. The pre-cleaning method for silicon carbide substrate leakage detection according to claim 1, characterized in that: In S2, the bubbling time of the bubbling water washing is 30s to 60s, and the overflow time is 5min to 15min.

8. The pre-cleaning method for silicon carbide substrate leakage detection according to claim 1, characterized in that: In S3, the soaking temperature is 40°C to 60°C, and the soaking time is 5min to 10min; and / or In S3, the bubbling time of the bubbling water washing is 30s to 60s, and the overflow time is 5min to 15min.

9. The pre-cleaning method for silicon carbide substrate leakage detection according to claim 1, characterized in that: In S3, the volume ratio of the sodium bicarbonate to water is 1:19 to 1:

9.

10. The pre-cleaning method for silicon carbide substrate leakage detection according to claim 1, characterized in that: In S3, a spin dryer is used to dry the cleaned silicon carbide substrate. The rotation speed of the spin dryer is 600 r / min to 1200 r / min, and the spin drying time is 5 min to 8 min.