A method for removing high points of a silicon carbide substrate flatness test plate

Abstract

The present invention relates to the field of silicon carbide technology, and specifically discloses a method for removing high points of a flatness test disk for a silicon carbide substrate. The present invention creatively proposes a method of using a simple rotating silicon carbide substrate to perform two measurements to determine whether the test disk is dirty, and for the first time proposes a method for accurately determining the position of a test dirty area and removing dirt using a flatness distribution map and a formula, and adopts different processing methods for precise areas of the test disk according to different degrees of dirt, thereby improving the effect of removing dirt from the test disk and ensuring the accuracy of the flatness test. At the same time, it also reduces the wear of the test disk surface caused by the traditional disk repair method, which not only effectively reduces the rework of the silicon carbide substrate caused by inaccurate testing, reduces the rework rate, and improves production efficiency, but also greatly improves the service life of the test disk, which is of great significance for reducing the production cost of the silicon carbide substrate and improving production efficiency, and has a high value for promotion and application.

Description

Technical Field

[0001] The invention relates to the technical field of silicon carbide, and in particular to a method for removing high points of a silicon carbide substrate flatness test disk. Background Art

[0002] With the development of semiconductor technology, silicon carbide (SiC), as a wide bandgap semiconductor material, has shown great application potential in high-power, high-frequency, and high-temperature electronic devices due to its excellent physical and chemical properties. As the basis of these devices, the flatness of the silicon carbide substrate directly affects the performance and reliability of the device. Although existing methods such as physical vapor transport (PVT) and liquid phase epitaxy (LPE) can produce high-quality silicon carbide substrates, these methods still face challenges in achieving high flatness. The surface roughness and lattice inhomogeneity of the silicon carbide substrate are still the key factors limiting device performance.

[0003] The main factors affecting the flatness of silicon carbide substrates are: raw material quality, preparation process, grinding technology, abrasives, etc. At the same time, an indispensable factor affecting the flatness test results of silicon carbide substrates is to ensure the accuracy of the flatness test results. One of the prerequisites for ensuring the accuracy of the test results is to ensure the cleanliness of the test disk.

[0004] If the cleanliness of the test disk is not enough, it will cause high points in the test flatness, affecting the judgment of the quality of the substrate. The dirt on the surface of the test disk will form a mark of the test disk on the back of the silicon carbide substrate. This back dirt cannot be effectively removed by conventional cleaning processes. Therefore, the silicon carbide substrate needs to be reworked, resulting in an increase in the rework rate and reduced production efficiency. Therefore, it is of great significance to find a method that can accurately determine the high points of the test disk and a method to remove the high points of the test disk. Summary of the invention

[0005] In order to solve the problem that high points appear in the silicon carbide substrate test due to contamination of the flatness test disc, which affects the accuracy of the flatness test result, the present invention provides a method for removing high points of the silicon carbide substrate flatness test disc. The method provided by the present invention effectively improves the accuracy of the flatness test by judging whether the high points appearing in the silicon carbide substrate test come from the test disc, and adopts different treatment methods according to the different degrees of dirtiness of the test disc, and reduces the wear of the test disc surface caused by the traditional disc repair method, thereby increasing the service life of the test disc, and has high practical value.

[0006] In order to solve the above technical problems, the technical solution provided by the present invention is:

[0007] A method for removing high points of a silicon carbide substrate flatness test plate comprises the following steps:

[0008] S1, placing the silicon carbide substrate on the test disc for the first test, and recording the high point position on the flatness distribution map; rotating the silicon carbide substrate by a preset angle for the second test, and recording the high point position on the flatness distribution map; if the high point positions of the two tests are consistent, it is determined that the test disc is dirty, and the process goes to S2; if the high point positions of the two tests are inconsistent, it is determined that the silicon carbide substrate is unqualified, and the silicon carbide substrate is reworked;

[0009] S2, determine the method of removing the high point of the test plate:

[0010] S201, counting the number M of continuous high point areas and the total number N of grids occupied by the continuous high point areas according to the flatness distribution map;

[0011] On the flatness distribution map, take the high point location as the center, extend D test cells up, down, left and right, correct the high point range to a quadrilateral with the least grid, and calculate the length L of the longest side of the quadrilateral after correction max ;

[0012] S202, matching the corrected high point area of ​​the flatness distribution map to the corresponding area of ​​the test disk, which is the area to be processed;

[0013] S203, if 0<M≤INT(Ф / 5d-1), 0<N≤2INT(Ф / 2d-2), and L max < Ф / 2, then physically clear the area to be processed; if M> INT(Ф / 5d-1) or N> 2INT(Ф / 2d-2) or L max ≥Ф / 2, the area to be processed is chemically cleaned; wherein Ф is the diameter of the silicon carbide substrate, mm; d is the side length of the test cell on the flatness distribution diagram, mm;

[0014] The physical cleaning method comprises the following steps: using a cleaning tape to adhere to the to-be-treated area of ​​the test disc to remove dirt and using a clean brush to clean the gaps in the to-be-treated area;

[0015] The chemical cleaning method comprises the following steps: using alkaline cleaning liquid to scrub and wash the area to be treated, using the alkaline cleaning liquid to scrub and wash the entire surface of the test disk, inverting the test disk and immersing it in water for ultrasonic cleaning, and drying it with nitrogen to obtain a clean test disk.

[0016] Compared with the prior art, the method for removing high points of a flatness test disk for a silicon carbide substrate provided by the present invention creatively proposes a method of using a simple rotation of the silicon carbide substrate to perform two measurements to determine whether the test disk is dirty, and for the first time proposes a method of using a flatness distribution map and a formula to accurately determine the position of the test dirty area and remove the dirt. Different treatment methods are used for precise areas of the test disk according to different degrees of dirt, which improves the effect of removing dirt from the test disk and ensures the accuracy of the flatness test. At the same time, it also reduces the wear on the test disk surface caused by the traditional disk repair method, which not only effectively reduces the rework of the silicon carbide substrate caused by inaccurate testing, reduces the rework rate, and improves production efficiency, but also greatly improves the service life of the test disk, which is of great significance for reducing the production cost of silicon carbide substrates and improving production efficiency, and has a high value for promotion and application.

[0017] Furthermore, in S1, the preset angle is 90°~180°.

[0018] Preferably, in S1, the preset angle is 180°.

[0019] Rotating the silicon carbide substrate by a preset angle can help to more easily and accurately determine whether the reason for the failure of the flatness test is due to the dirtiness of the test disk or the failure of the silicon carbide flatness, thereby improving the ease of operation.

[0020] It should be noted that in the present invention, the location where a continuous high point area appears is recorded as 1, and the total number of continuous high point areas in the flatness distribution diagram is represented by M; each continuous high point area is composed of one or more high point units (i.e., test cells), and the total number of high point units is represented by N. The diameter of the silicon carbide substrate is represented by Φ; the side length of the test cell is d, and there are generally two specifications of 5mm*5mm and 10mm*10mm.

[0021] The above continuous area refers to the area where the test cells are connected without any gaps.

[0022] Furthermore, the physical cleaning method specifically includes the following steps: covering the area to be processed of the test disc with a cleaning tape, cleaning the gaps in the area to be processed with a clean brush after removing the cleaning tape, and finally covering the area to be processed with the cleaning tape again, removing the cleaning tape, and obtaining a clean test disc.

[0023] As a specific implementation of the present invention, the high point position is corrected to a square or rectangle with the least grid space by extending D cells up, down, left, and right.

[0024] It should be noted that in S202, the high point area after the correction of the flatness distribution map can be matched to the corresponding area of ​​the test disk in a variety of ways. Exemplarily, the flatness distribution map can be printed on the model or purification paper at a ratio of 1:1, and the corrected quadrilateral can be cut into a hollow position on the model or purification paper, and the model or purification paper can be fixed on a plastic chuck, which is circular, hollowed in the middle, and has a diameter less than 5mm of the diameter of the silicon carbide substrate. Then, the plastic chuck is suspended and fixed directly above the test disk, so that the plastic chuck is aligned with the center of the test disk, and the laser pen is used to scan along the hollow position. The position where the laser pen shines on the test disk is the position to be processed. Other methods can also be used to match the corrected quadrilateral on the flatness distribution map to the test disk, such as selecting a non-reflective model material to make a non-hollow area, and selecting a penetrating light to shine the corrected quadrilateral on the test disk to determine the area to be processed. The present invention does not specifically limit the specific matching method.

[0025] Furthermore, in S203, the cleaning tape is a polyethylene tape with an ISO grade of 3 to 6; and the width of the cleaning tape is greater than the stripe spacing of the test disk.

[0026] The polyethylene tape should be selected based on the length that can cover the entire area to be treated and the minimum number of adhesions. For example, if the corrected rectangle is 50mm long and 20mm wide, the tape can be 20mm or 25mm wide. If the 20mm specification is selected, a 50mm long piece of tape can be used for adhesion; if the 25mm specification is selected, 20mm is used as the length of each piece of tape, and two pieces of tape are selected for adhesion.

[0027] Further, in S203, a clean soft brush is used to clean the test disk from inside to outside in a clockwise or counterclockwise direction.

[0028] Use polyethylene tape (ISO 3~6 grade) which is easy to remove and leaves no residue to remove the large particles remaining on the test disc, then use a brush to remove the residual particles in the gaps, and finally use polyethylene tape to remove the residual particles in the gaps, which can effectively remove the residual dirt on the test disc and avoid the wear on the test disc surface caused by repairing the disc.

[0029] Further, in S203, the alkaline cleaning solution includes the following components in mass fractions: 2% to 5% sodium bicarbonate, 1% to 3% sodium lauryl sulfate, 1% to 3% dodecyl dimethyl amine oxide, 3% to 7% coconut oil fatty acid diethanolamide, 0.05% to 0.2% sodium benzoate, and the balance is water.

[0030] The preferred cleaning solution can fully remove dirt from the test disk without causing adverse effects on the disk surface of the test disk.

[0031] It should be noted that the alkaline cleaning solution is diluted according to the volume ratio of ultrapure deionized water to alkaline cleaning solution of 10:1 to 30:1 before use.

[0032] Further, in S203, during brushing, the brushing direction is from inside to outside along the texture of the test disk, and brushing is performed clockwise or counterclockwise, and the brushing time is 5 minutes to 10 minutes.

[0033] Furthermore, in S203, during water washing, the test plate is placed vertically and water is flushed from top to bottom.

[0034] Further, in S203, the ultrasonic cleaning step is specifically as follows: firstly ultrasonicate at 50kHZ~70kHZ for 5min~10min, then ultrasonicate at 70kHZ~90kHZ for 5min~10min, and finally ultrasonicate at 100kHZ~120kHZ for 5min~10min.

[0035] Specifically, ultrapure deionized water is placed in the ultrasonic pool, and buckles are provided in the ultrasonic pool to support and fix the test disc. The number of buckles is 3 to 4. If 3 buckles are provided, the angle of the buckles is set to 120°, and if 4 buckles are provided, the angle of the buckles is set to 90°. The test disc is placed upside down in the ultrasonic pool. It should be noted that the test surface (i.e., the contact surface with the silicon carbide substrate) is the front side.

[0036] It should be noted that after each ultrasonic frequency is finished, the buckle is rotated. Set 3 buckles to rotate the test disc clockwise or counterclockwise horizontally, 0°<rotation angle<120°. Set 4 buckles to rotate the test disc clockwise or counterclockwise horizontally, 0°<rotation angle<90°.

[0037] Furthermore, in S203, the purity of the nitrogen is ≥99.99%.

[0038] Compared with the prior art, the beneficial effect of the present technical solution is that the method for removing high points of a silicon carbide substrate flatness test disk provided by the present invention can quickly and accurately judge whether the test disk is dirty, and divide the degree of dirtiness of the test disk according to a specific formula, and select different treatment methods according to the degree of dirtiness of the test disk, thereby achieving efficient cleaning of the test disk and ensuring the cleanliness of the test disk, thereby improving the accuracy of the flatness test results and reducing the problem of high rework rate of silicon carbide caused by inaccurate judgment results. At the same time, the cleaning method of the test disk provided by the present invention will not cause wear to the disk surface of the test disk, and can significantly improve the service life of the test disk, which can play a positive role in improving the production efficiency and reducing the production cost of silicon carbide substrates, and has broad application prospects in the field of silicon carbide substrate production. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 Schematic diagram of the process of removing high points of a silicon carbide substrate flatness test plate in an embodiment of the present invention;

[0040] Figure 2 This is a flatness distribution diagram of a silicon carbide substrate tested before the test disk is processed in Example 1 of the present invention, wherein (a) is before correction, and (b) is after correction;

[0041] Figure 3 This is a flatness distribution diagram of a silicon carbide substrate tested after being processed by a test disk in Example 1 of the present invention;

[0042] Figure 4 This is a flatness distribution diagram of a silicon carbide substrate tested before the test disk is processed in Example 2 of the present invention, wherein (a) is before correction, and (b) is after correction;

[0043] Figure 5 This is a flatness distribution diagram of a silicon carbide substrate tested after being processed by a test disk in Example 2 of the present invention;

[0044] Figure 6 This is a flatness distribution diagram of a silicon carbide substrate tested before the test disk is processed in Example 3 of the present invention, wherein (a) is before correction, and (b) is after correction;

[0045] Figure 7 This is a flatness distribution diagram of a silicon carbide substrate tested after being processed by a test disk in Example 3 of the present invention;

[0046] Figure 8 This is a flatness distribution diagram of a silicon carbide substrate tested before the test disk is processed in Example 4 of the present invention, wherein (a) is before correction, and (b) is after correction;

[0047] Fig. 9 This is a flatness distribution diagram of a silicon carbide substrate tested after being processed by a test disk in Example 4 of the present invention;

[0048] Fig.10 This is a flatness distribution diagram of a silicon carbide substrate tested before the test disk is processed in Example 5 of the present invention, wherein (a) is before correction, and (b) is after correction;

[0049] Fig.11 This is a flatness distribution diagram of a silicon carbide substrate tested after being processed by a test disk in Example 5 of the present invention;

[0050] Fig.12 This is a flatness distribution diagram of a silicon carbide substrate tested before the test disk is processed in Example 6 of the present invention, wherein (a) is before correction, and (b) is after correction;

[0051] Fig.13This is a flatness distribution diagram of a silicon carbide substrate tested after being processed by a test disk in Example 6 of the present invention;

[0052] Fig.14 This is a flatness distribution diagram of a silicon carbide substrate tested before the test disk is processed in Example 7 of the present invention, wherein (a) is before correction, and (b) is after correction;

[0053] Fig.15 This is a flatness distribution diagram of a silicon carbide substrate tested after being processed by a test disk in Example 7 of the present invention;

[0054] Fig.16 This is a flatness distribution diagram of the silicon carbide substrate tested before and after the test disk treatment in Comparative Example 1 of the present invention, wherein (a) before treatment, (b) after treatment;

[0055] Fig.17 This is a flatness distribution diagram of the silicon carbide substrate tested before and after the test disk treatment in Comparative Example 2 of the present invention, wherein (a) before treatment, (b) after treatment;

[0056] Fig.18 This is a flatness distribution diagram of the silicon carbide substrate tested before the test disk is processed in Comparative Example 3 of the present invention, wherein (a) before correction, (b) after correction;

[0057] Fig.19 This is a flatness distribution diagram of a silicon carbide substrate tested after being processed by a test disk in Comparative Example 3 of the present invention;

[0058] Fig. 20 This is a flatness distribution diagram of the silicon carbide substrate tested before and after the test disk treatment in Comparative Example 4 of the present invention, wherein (a) before treatment, (b) after treatment;

[0059] Fig.21 This is a flatness distribution diagram of the silicon carbide substrate tested before the test disk treatment in Comparative Example 5 of the present invention, wherein (a) before correction, (b) after correction;

[0060] Fig. 22 This is a flatness distribution diagram of a silicon carbide substrate tested after being processed by a test disk in Comparative Example 5 of the present invention;

[0061] Fig.23 This is a flatness distribution diagram of the silicon carbide substrate tested before the test disk treatment in Comparative Example 6 of the present invention, wherein (a) before correction, (b) after correction;

[0062] Fig.24 This is a flatness distribution diagram of a silicon carbide substrate tested after being processed by a test disk in Comparative Example 6 of the present invention;

[0063] Fig.25 This is a flatness distribution diagram of the silicon carbide substrate tested before the test disk treatment in Comparative Example 7 of the present invention, wherein (a) before correction, (b) after correction;

[0064] Fig.26 This is a flatness distribution diagram of the silicon carbide substrate tested after the test disk was processed in Comparative Example 7 of the present invention. DETAILED DESCRIPTION

[0065] 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.

[0066] In order to better illustrate the present invention, further examples are given below.

[0067] The silicon carbide substrate used in the following examples and comparative examples is a 6-inch conductive substrate, the side length of the test unit cell in the flatness distribution diagram is 10 mm, and the width of the polyethylene tape (ISO grade 3) is 20 mm or 30 mm. The purity of the nitrogen used is ≥99.99%.

[0068] The test discs used in the following embodiments and comparative examples all have high points when testing the flatness of the silicon carbide substrate, and after being rotated 180° for a second test, the high point position remains unchanged, and the high point position is determined to be a dirty test disc on the test disc.

[0069] The schematic diagram of the process of removing the high point of the silicon carbide substrate flatness test plate in the following embodiment is as follows: Figure 1 As shown, the specific process is described in detail in conjunction with the following embodiments.

[0070] Example 1

[0071] This embodiment provides a method for removing high points of a silicon carbide substrate flatness test plate, comprising the following steps:

[0072] S1, flatness test of silicon carbide substrate Figure 2 As shown in (a), the number of continuous high point areas is M=1, and the total number of grids occupied by high point areas is N=1;

[0073] S2, with the high point as the center, extend one test cell up, down, left and right, and correct the high point to the square with the least grid, such as Figure 2 As shown in (b), the L of the corrected square max =2×10=20mm;

[0074] S3, determine the liquidation method: 0<M=1≤INT(Ф / 5d-1)=INT(150 / (5×10)-1)=2, 0<N=1≤2INT(Ф / 2d-2)=2INT(150 / (2×10)-2)=10, and L max=20<Ф / 2=150 / 2=75, choose the physical liquidation method;

[0075] S4, matching the correction square in the flatness distribution map to the test disk, adhering the test disk with a 20 mm×20 mm polyethylene tape according to the determined cleaning range (a square with a side length of 20 mm), and removing the polyethylene tape;

[0076] Use a clean soft brush to clean the gaps in the determined cleaning range clockwise from the inside to the outside along the stripes of the test disk;

[0077] Then, the determined cleaning range is adhered with polyethylene tape, and the polyethylene tape is removed to obtain the processed test disk;

[0078] S5, the above-treated test disc is used for the flatness test of the silicon carbide substrate. After rotating it 180°, the high spots disappear, proving that the test disc is cleaned. The test results are as follows: Figure 3 shown.

[0079] Example 2

[0080] This embodiment provides a method for removing high points of a silicon carbide substrate flatness test plate, comprising the following steps:

[0081] S1, flatness test of silicon carbide substrate Figure 4 As shown in (a), the number of continuous high point areas is M=1, and the total number of grids occupied by high point areas is N=10;

[0082] S2, with the high point as the center, extend one test cell up, down, left and right, and correct the high point to a rectangle with the least grid space, such as Figure 4 As shown in (b), the L of the corrected rectangle is max =7×10=70mm;

[0083] S3, determine the liquidation method: 0<M=1≤INT(Ф / 5d-1)=INT(150 / (5×10)-1)=2, 0<N=1≤2INT(Ф / 2d-2)=2INT(150 / (2×10)-2)=10, and L max =70<Ф / 2=150 / 2=75, choose the physical liquidation method;

[0084] S4, matching the correction rectangle in the flatness distribution map to the test disk, adhering the test disk with a 20 mm × 70 mm polyethylene tape according to the determined cleaning range (a rectangle with a length of 70 mm and a width of 40 mm), and removing the polyethylene tape;

[0085] Use a clean soft brush to clean the gaps in the determined cleaning range counterclockwise from inside to outside along the stripes of the test disk;

[0086] Then, the determined cleaning range is adhered with polyethylene tape, and the polyethylene tape is removed to obtain the processed test disk;

[0087] S5, the above-treated test disc is used for the flatness test of the silicon carbide substrate. After rotating it 180°, the high spots disappear, proving that the test disc is cleaned. The test results are as follows: Figure 5 shown.

[0088] Example 3

[0089] This embodiment provides a method for removing high points of a silicon carbide substrate flatness test plate, comprising the following steps:

[0090] S1, flatness test of silicon carbide substrate Figure 6 As shown in (a), the number of continuous high-point areas is M=2, and the total number of grids occupied by high-point areas is N=2;

[0091] S2, with the high point as the center, extend one test cell up, down, left and right, and correct the high point to the square with the least grid, such as Figure 6 As shown in (b), the L of the corrected square max =2×10=20mm;

[0092] S3, determine the liquidation method: 0<M=2≤INT(Ф / 5d-1)=INT(150 / (5×10)-1)=2, 0<N=2≤2INT(Ф / 2d-2)=2INT(150 / (2×10)-2)=10, and L max =20<Ф / 2=150 / 2=75, choose the physical liquidation method;

[0093] S4, match the correction square in the flatness distribution map to the test disk, and adhere the test disk twice with a 20 mm × 20 mm polyethylene tape according to the determined cleaning range (two squares with a side length of 20 mm), and the polyethylene tape is not reused, and the polyethylene tape is removed;

[0094] Use a clean soft brush to clean the gaps in the determined cleaning range clockwise from the inside to the outside along the stripes of the test disk;

[0095] Then, the determined cleaning range is adhered with polyethylene tape, and the polyethylene tape is removed to obtain the processed test disk;

[0096] S5, the above-treated test disc is used for the flatness test of the silicon carbide substrate. After rotating it 180°, the high spots disappear, proving that the test disc is cleaned. The test results are as follows: Figure 7 shown.

[0097] Example 4

[0098] This embodiment provides a method for removing high points of a silicon carbide substrate flatness test plate, comprising the following steps:

[0099] S1, flatness test of silicon carbide substrate Figure 8 As shown in (a), the number of continuous high-point areas is M=2, and the total number of grids occupied by high-point areas is N=4;

[0100] S2, with the high point as the center, extend one test cell up, down, left and right, and correct the high point to a rectangle with the least grid space, such as Figure 8 As shown in (b), the L of the corrected rectangle is max =4×10=40mm;

[0101] S3, determine the liquidation method: 0<M=2≤INT(Ф / 5d-1)=INT(150 / (5×10)-1)=2, 0<N=4≤2INT(Ф / 2d-2)=2INT(150 / (2×10)-2)=10, and L max =40<Ф / 2=150 / 2=75, choose the physical liquidation method;

[0102] S4, match the correction rectangle in the flatness distribution map to the test disk, and adhere the test disk twice with 20 mm × 30 mm polyethylene tape according to the determined cleaning range (two rectangles with a length of 40 mm and a width of 30 mm). The tape is not reused and the polyethylene tape is removed;

[0103] Use a clean soft brush to clean the gaps in the determined cleaning range clockwise from the inside to the outside along the stripes of the test disk;

[0104] Then, the determined cleaning range is adhered with polyethylene tape, and the polyethylene tape is removed to obtain the processed test disk;

[0105] S5, the above-treated test disc is used for the flatness test of the silicon carbide substrate. After rotating it 180°, the high spots disappear, proving that the test disc is cleaned. The test results are as follows: Fig. 9 shown.

[0106] Example 5

[0107] This embodiment provides a method for removing high points of a silicon carbide substrate flatness test plate, comprising the following steps:

[0108] S1, flatness test of silicon carbide substrate Fig.10 As shown in (a), the number of continuous high-point areas is M=2, and the total number of grids occupied by high-point areas is N=10;

[0109] S2, with the high point as the center, extend one test cell up, down, left and right, and correct the high point to a quadrilateral with the least grid, such as Fig.10 (b) shows the L of the corrected quadrilateral. max =5×10=50mm;

[0110] S3, determine the liquidation method: 0<M=2≤INT(Ф / 5d-1)=INT(150 / (5×10)-1)=2, 0<N=10≤2INT(Ф / 2d-2)=2INT(150 / (2×10)-2)=10, and L max =50<Ф / 2=150 / 2=75, choose the physical liquidation method;

[0111] S4, match the correction quadrilateral in the flatness distribution map to the test disk, and adhere the test disk with 20mm×40mm and 20mm×50mm polyethylene tapes respectively according to the determined cleaning range (a square with a side length of 40mm and a rectangle with a length of 50mm and a width of 40mm). The tapes are not reused and the polyethylene tapes are removed;

[0112] Use a clean soft brush to clean the gaps in the determined cleaning range clockwise from the inside to the outside along the stripes of the test disk;

[0113] Then, the determined cleaning range is adhered with polyethylene tape, and the polyethylene tape is removed to obtain the processed test disk;

[0114] S5, the above-treated test disc is used for the flatness test of the silicon carbide substrate. After rotating it 180°, the high spots disappear, proving that the test disc is cleaned. The test results are as follows: Fig.11 shown.

[0115] Example 6

[0116] This embodiment provides a method for removing high points of a silicon carbide substrate flatness test plate, comprising the following steps:

[0117] S1, flatness test of silicon carbide substrate Fig.12 As shown in (a), the number of continuous high point areas is M=1, and the total number of grids occupied by high point areas is N=12;

[0118] S2, with the high point as the center, extend one test cell up, down, left and right, and correct the high point to a rectangle with the least grid space, such as Fig.12 As shown in (b), the L of the corrected rectangle is max =8×10=80mm;

[0119] S3, determine the liquidation method: 0<M=1≤INT(Ф / 5d-1)=INT(150 / (5×10)-1)=2, 0<N=12>2INT(Ф / 2d-2)=2INT(150 / (2×10)-2)=10, L max =80>Ф / 2=150 / 2=75, choose chemical cleaning method;

[0120] S4, matching the correction rectangle in the flatness distribution map to the test disk, according to the determined cleaning range (rectangle with a length of 80 mm and a width of 40 mm);

[0121] S5, dilute the alkaline cleaning solution with ultrapure deionized water in a volume ratio of 1:10, use a clean soft-bristled brush to dip the diluted alkaline cleaning solution and scrub the determined cleaning range, scrubbing along the texture of the test disk from the inside to the outside, scrubbing in a fixed clockwise direction for 5 minutes, and then rinse the test disk with ultrapure deionized water. When rinsing, place the test disk vertically with the scrubbing position facing downward, and rinse from top to bottom with the ultrapure deionized water nozzle to avoid splashing;

[0122] The alkaline cleaning solution comprises the following components in percentage by mass: 2% sodium bicarbonate, 1% sodium lauryl sulfate, 1% dodecyl dimethyl amine oxide, 3% coconut oil fatty acid diethanolamide, 0.05% sodium benzoate, and the balance is water.

[0123] S6, replace a new soft-bristle brush, dip it in the diluted alkaline cleaning solution, and scrub the entire surface of the test disk from the inside to the outside along the texture of the test disk in a fixed clockwise direction for 5 minutes. Then rinse the test disk with ultrapure deionized water. When rinsing, place the test disk vertically and rotate it to rinse until there is no alkaline cleaning solution left on the surface;

[0124] S7, ultrapure deionized water is placed in the ultrasonic pool, and the ultrasonic pool is provided with 3 buckles, and the buckles are distributed at an angle of 120°. The test disk is fixed on the buckles with the front side facing downward, and ultrasonicated at 50kHZ for 10 minutes, then at 70kHZ for 10 minutes, and finally at 100kHZ for 10 minutes. After each frequency of ultrasonication, the buckle is rotated horizontally counterclockwise at a rotation angle of 30°; blow dried with nitrogen, and let stand for 5 minutes to obtain the processed test disk;

[0125] S8, the above-treated test disc is used for the flatness test of the silicon carbide substrate. After rotating the test disc 180°, the high spots disappear, proving that the test disc is cleaned. The test results are as follows: Fig.13 shown.

[0126] Example 7

[0127] This embodiment provides a method for removing high points of a silicon carbide substrate flatness test plate, comprising the following steps:

[0128] S1, flatness test of silicon carbide substrate Fig.14 As shown in (a), the number of continuous high-point areas is M=3, and the total number of grids occupied by high-point areas is N=9;

[0129] S2, with the high point as the center, extend one test cell up, down, left and right, and correct the high point to the square with the least grid, such as Fig.14 As shown in (b), the L of the corrected square max =4×10=40mm;

[0130] S3, determine the liquidation method: 0<M=3>INT(Ф / 5d-1)=INT(150 / (5×10)-1)=2, 0<N=9≤2INT(Ф / 2d-2)=2INT(150 / (2×10)-2)=10, L max =40<Ф / 2=150 / 2=75, choose chemical cleaning method;

[0131] S4, matching the correction square in the flatness distribution map to the test disk, according to the determined cleaning range (3 squares with a side length of 40 mm);

[0132] S5, dilute the alkaline cleaning solution with ultrapure deionized water in a volume ratio of 1:30, use a clean soft-bristled brush to dip the diluted alkaline cleaning solution to scrub the determined cleaning range, scrubbing along the texture of the test disk from the inside to the outside, scrubbing in a fixed clockwise direction for 10 minutes, and then rinse the test disk with ultrapure deionized water. When rinsing, place the test disk vertically with the scrubbing position facing downward, and rinse from top to bottom with the ultrapure deionized water nozzle to avoid splashing;

[0133] The alkaline cleaning solution comprises the following components in percentage by weight: 5% sodium bicarbonate, 3% sodium lauryl sulfate, 3% dodecyl dimethyl amine oxide, 7% coconut oil fatty acid diethanolamide, 0.2% sodium benzoate, and the balance is water.

[0134] S6, replace a new soft-bristle brush, dip it in the diluted alkaline cleaning solution, and scrub the entire surface of the test disk from the inside to the outside along the texture of the test disk in a fixed clockwise direction for 10 minutes. Then rinse the test disk with ultrapure deionized water. When rinsing, place the test disk vertically and rotate it to rinse until there is no alkaline cleaning solution left on the surface;

[0135] S7, ultrapure deionized water is placed in the ultrasonic pool, and the ultrasonic pool is provided with 4 buckles, and the buckles are distributed at an angle of 90°. The test disk is fixed on the buckles with the front side facing downward, and ultrasonicated at 70HZ for 5 minutes, then at 90kHZ for 5 minutes, and finally at 120kHZ for 5 minutes. After each frequency of ultrasonication, the buckle is rotated horizontally counterclockwise at a rotation angle of 45°; blow-dried with nitrogen, and left to stand for 10 minutes to obtain the treated test disk;

[0136] S8, the above-treated test disc is used for the flatness test of the silicon carbide substrate. After rotating the test disc 180°, the high spots disappear, proving that the test disc is cleaned. The test results are as follows: Fig.15 shown.

[0137] Comparative Example 1

[0138] This comparative example provides a method for removing high points of a silicon carbide substrate flatness test plate, comprising the following steps:

[0139] S1, flatness test of silicon carbide substrate Fig.16 As shown in (a), the corresponding high point of the test plate is wiped with a dust-free cloth. After multiple wipes, a silicon carbide wafer with qualified flatness is used for flatness test. The results are as follows: Fig.16 As shown in (b), it can be seen from the figure that the high point in the test plate has not been cleared and the high point range has increased.

[0140] Comparative Example 2

[0141] This comparative example provides a method for removing high points of a silicon carbide substrate flatness test plate, comprising the following steps:

[0142] S1, flatness test of silicon carbide substrate Fig.17 As shown in (a), the high points of the test disk are processed by the traditional repair method: a clean silicon carbide substrate is used as a cleaning sheet, and the carbon surface of the cleaning sheet is used to rub the high points of the test disk, and then the entire test disk is rubbed along the texture of the test disk in a clockwise direction to make the entire test disk flat. After cleaning the test disk, a silicon carbide sheet with qualified flatness is used for flatness testing. The results are shown in FIG. Fig.17 As shown in (b), it can be seen from the figure that some high points in the test plate have not been cleared.

[0143] Comparative Example 3

[0144] This comparative example provides a method for removing high points of a silicon carbide substrate flatness test plate, comprising the following steps:

[0145] S1, flatness test of silicon carbide substrate Fig.18 As shown in (a), with the high point as the center, extend one test cell up, down, left and right, and correct the high point to the square with the least grid space, as shown in Fig.18 As shown in (b), the side length of the corrected square is 40 mm;

[0146] S2, match the correction square in the flatness distribution map to the test disk, and adhere the test disk with 20mm×40mm polyethylene tape according to the determined cleaning range (3 squares with a side length of 40mm). The tape is not reused and the polyethylene tape is removed;

[0147] Use a clean soft brush to clean the gaps in the determined cleaning range clockwise from the inside to the outside along the stripes of the test disk;

[0148] Then, the determined cleaning range is adhered with polyethylene tape, and the polyethylene tape is removed to obtain the processed test disk;

[0149] S3, use the silicon carbide wafer with qualified flatness to conduct flatness test, the test results are as follows Fig.19 As shown in the figure, it can be seen that for the test disk with serious pollution, the physical cleaning method is used, but the problem of high points on the test disk is not completely solved.

[0150] Comparative Example 4

[0151] This comparative example provides a method for removing high points of a silicon carbide substrate flatness test plate, comprising the following steps:

[0152] S1, flatness test of silicon carbide substrate Fig. 20 As shown in (a), the positions of the high points on the test disk are visually located according to the flatness distribution diagram, and 20 mm × 40 mm polyethylene tape is used to adhere the approximate positions of the high points on the test disk. The tape is not reused and the polyethylene tape is removed;

[0153] Use a clean soft brush to clean the gaps in the determined cleaning range clockwise from the inside to the outside along the stripes of the test disk;

[0154] Then, the determined cleaning range is adhered with polyethylene tape, and the polyethylene tape is removed to obtain the processed test disk;

[0155] S3, use the silicon carbide wafer with qualified flatness to conduct flatness test, the test results are as follows Fig. 20 As shown in (b). It can be seen from the figure that the problem of the high point of the test plate has not been completely solved.

[0156] Comparative Example 5

[0157] This embodiment provides a method for removing high points of a silicon carbide substrate flatness test plate, comprising the following steps:

[0158] S1, flatness test of silicon carbide substrate Fig.21As shown in (a), the number of continuous high point areas is M=1, and the total number of grids occupied by high point areas is N=12;

[0159] S2, with the high point as the center, extend one test cell up, down, left and right, and correct the high point to the square with the least grid, such as Fig.21 As shown in (b), the L of the corrected square max =6×10=60mm;

[0160] S3, determine the liquidation method: 0<M=1≤INT(Ф / 5d-1)=INT(150 / (5×10)-1)=2, 0<N=12>2INT(Ф / 2d-2)=2INT(150 / (2×10)-2)=10, L max =60<Ф / 2=150 / 2=75, choose chemical cleaning method;

[0161] S4, matching the correction square in the flatness distribution map to the test disk, according to the determined cleaning range (rectangle with a length of 60 mm and a width of 50 mm);

[0162] S5, dilute the acid cleaning solution with ultrapure deionized water in a volume ratio of 1:10, use a clean soft-bristled brush to dip the diluted acid cleaning solution and scrub the determined cleaning range, scrubbing along the texture of the test disk from the inside to the outside, scrubbing in a fixed clockwise direction for 5 minutes, and then rinse the test disk with ultrapure deionized water. When rinsing, place the test disk vertically with the scrubbing position facing downward, and rinse from top to bottom with the ultrapure deionized water nozzle to avoid splashing;

[0163] The alkaline cleaning solution comprises the following components in percentage by weight: 2% citric acid, 1% sodium lauryl sulfate, 1% dodecyl dimethyl amine oxide, 3% coconut oil fatty acid diethanolamide, 0.05% sodium benzoate, and the balance is water.

[0164] S6, replace a new soft-bristle brush, dip it in the diluted acidic cleaning solution, and scrub the entire surface of the test disk from the inside to the outside along the texture of the test disk in a fixed clockwise direction for 5 minutes. Then rinse the test disk with ultrapure deionized water. When rinsing, place the test disk vertically and rotate it to rinse until there is no residual acidic cleaning solution on the surface;

[0165] S7, ultrapure deionized water is placed in the ultrasonic pool, and the ultrasonic pool is provided with 3 buckles, and the buckles are distributed at an angle of 120°. The test disk is fixed on the buckles with the reverse side facing downward, and ultrasonicated at 50kHZ for 10 minutes, then at 70kHZ for 10 minutes, and finally at 100kHZ for 10 minutes. After each frequency of ultrasonication, the buckle is rotated horizontally counterclockwise at a rotation angle of 30°; blown dry with nitrogen, and allowed to stand for 5 minutes to obtain the treated test disk;

[0166] S8, use the silicon carbide wafer with qualified flatness to conduct flatness test, the test results are as follows Fig. 22 As shown in the figure, it can be seen that the problem of the high point of the test plate has not been completely solved.

[0167] Comparative Example 6

[0168] This comparative example provides a method for removing high points of a silicon carbide substrate flatness test plate. The only difference from Example 6 is that during ultrasonic cleaning, the test plate is placed upright. The specific steps are as follows:

[0169] S1, flatness test of silicon carbide substrate Fig.23 As shown in (a), the number of continuous high point areas is M=1, and the total number of grids occupied by high point areas is N=12;

[0170] S2, with the high point as the center, extend one test cell up, down, left and right, and correct the high point to a rectangle with the least grid space, such as Fig.23 As shown in (b), the L of the corrected rectangle is max =6×10=60mm;

[0171] S3, determine the liquidation method: 0<M=1≤INT(Ф / 5d-1)=INT(150 / (5×10)-1)=2, 0<N=12>2INT(Ф / 2d-2)=2INT(150 / (2×10)-2)=10, L max =60<Ф / 2=150 / 2=75, choose chemical cleaning method;

[0172] S4, matching the correction rectangle in the flatness distribution map to the test disk, according to the determined cleaning range (rectangle with a length of 60 mm and a width of 50 mm);

[0173] S5, dilute the alkaline cleaning solution with ultrapure deionized water in a volume ratio of 1:10, use a clean soft-bristled brush to dip the diluted alkaline cleaning solution and scrub the determined cleaning range, scrubbing along the texture of the test disk from the inside to the outside, scrubbing in a fixed clockwise direction for 5 minutes, and then rinse the test disk with ultrapure deionized water. When rinsing, place the test disk vertically with the scrubbing position facing downward, and rinse from top to bottom with the ultrapure deionized water nozzle to avoid splashing;

[0174] The alkaline cleaning solution comprises the following components in percentage by mass: 2% sodium bicarbonate, 1% sodium lauryl sulfate, 1% dodecyl dimethyl amine oxide, 3% coconut oil fatty acid diethanolamide, 0.05% sodium benzoate, and the balance is water.

[0175] S6, replace a new soft-bristle brush, dip it in the diluted alkaline cleaning solution, and scrub the entire surface of the test disk from the inside to the outside along the texture of the test disk in a fixed clockwise direction for 5 minutes. Then rinse the test disk with ultrapure deionized water. When rinsing, place the test disk vertically and rotate it to rinse until there is no alkaline cleaning solution left on the surface;

[0176] S7, ultrapure deionized water is placed in the ultrasonic pool, and the ultrasonic pool is provided with 3 buckles, and the buckles are distributed at an angle of 120°. The test disk is fixed on the buckles with the front side facing up, and ultrasonicated at 50kHZ for 10 minutes, then at 70kHZ for 10 minutes, and finally at 100kHZ for 10 minutes. After each frequency of ultrasonication, the buckle is rotated horizontally counterclockwise at a rotation angle of 30°; blow dried with nitrogen, and let stand for 5 minutes to obtain the treated test disk;

[0177] S8, use the silicon carbide wafer with qualified flatness to conduct flatness test, the test results are as follows Fig.24 As shown in the figure, it can be seen that the problem of the high point of the test plate has not been completely solved.

[0178] Comparative Example 7

[0179] This comparative example provides a method for removing high points of a silicon carbide substrate flatness test plate. The only difference from Example 6 is that during ultrasonic cleaning, the test plate is placed upright. The specific steps are as follows:

[0180] S1, flatness test of silicon carbide substrate Fig.25 As shown in (a), the number of continuous high point areas is M=1, and the total number of grids occupied by high point areas is N=12;

[0181] S2, with the high point as the center, extend one test cell up, down, left and right, and correct the high point to a rectangle with the least grid space, such as Fig.25 As shown in (b), the L of the corrected rectangle is max =6×10=60mm;

[0182] S3, determine the liquidation method: 0<M=1≤INT(Ф / 5d-1)=INT(150 / (5×10)-1)=2, 0<N=12>2INT(Ф / 2d-2)=2INT(150 / (2×10)-2)=10, L max =60<Ф / 2=150 / 2=75, choose chemical cleaning method;

[0183] S4, matching the correction rectangle in the flatness distribution map to the test disk, according to the determined cleaning range (rectangle with a length of 60 mm and a width of 50 mm);

[0184] S5, dilute the alkaline cleaning solution with ultrapure deionized water in a volume ratio of 1:10, use a clean soft-bristled brush to dip the diluted alkaline cleaning solution and scrub the determined cleaning range, scrubbing along the texture of the test disk from the inside to the outside, scrubbing in a fixed clockwise direction for 5 minutes, and then rinse the test disk with ultrapure deionized water. When rinsing, place the test disk vertically with the scrubbing position facing downward, and rinse from top to bottom with the ultrapure deionized water nozzle to avoid splashing;

[0185] The alkaline cleaning solution comprises the following components in percentage by mass: 2% sodium bicarbonate, 1% sodium lauryl sulfate, 1% dodecyl dimethyl amine oxide, 3% coconut oil fatty acid diethanolamide, 0.05% sodium benzoate, and the balance is water.

[0186] S6, replace a new soft-bristle brush, dip it in the diluted alkaline cleaning solution, and scrub the entire surface of the test disk from the inside to the outside along the texture of the test disk in a fixed clockwise direction for 5 minutes. Then rinse the test disk with ultrapure deionized water. When rinsing, place the test disk vertically and rotate it to rinse until there is no alkaline cleaning solution left on the surface;

[0187] S7, ultrapure deionized water is placed in the ultrasonic pool, and the ultrasonic pool is provided with 3 buckles, and the buckles are distributed at an angle of 120°. The test disk is fixed on the buckles with the front side facing up, and ultrasonicated at 50kHZ for 10 minutes, then at 70kHZ for 10 minutes, and finally at 100kHZ for 10 minutes. After each frequency of ultrasonication, the buckle is rotated horizontally counterclockwise at a rotation angle of 30°; blown dry with compressed air, and left to stand for 5 minutes, and the test disk is processed;

[0188] S8, use the silicon carbide wafer with qualified flatness to conduct flatness test, the test results are as follows Fig.26 As shown in the figure, it can be seen that the high point problem of the test plate has not been completely solved, and the high point range has increased.

[0189] The cleaning effects of different cleaning methods of Example 1 to Example 7 and Comparative Example 1 to Comparative Example 7 are summarized in Table 1:

[0190] Table 1

[0191]

[0192] 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 method for removing high points of a silicon carbide substrate flatness test plate, characterized in that: The steps include: S1, placing the silicon carbide substrate on a test plate for a first test, and recording the high point position on a flatness distribution map; rotating the silicon carbide substrate by a preset angle for a second test, and recording the high point position on a flatness distribution map; If the high points of the two tests are consistent, the test plate is determined to be dirty and the process goes to S2; If the high point positions of the two tests are inconsistent, the silicon carbide substrate is judged to be unqualified and the silicon carbide substrate is reworked; S2, determine the method of removing the high point of the test plate: S201, counting the number M of continuous high point areas and the total number N of grids occupied by the continuous high point areas according to the flatness distribution map; On the flatness distribution map, take the high point location as the center, extend several test cells up, down, left, and right, respectively, correct the high point range to a quadrilateral with the least grid, and calculate the length L of the longest side of the corrected quadrilateral max ; If the high point is located at the edge of the flat distribution map, it will only extend at least one cell into the flat distribution map. If the high point is not at the edge, it will be centered at the high point and extended up, down, left, and right by several cells respectively. S202, matching the corrected high point area of ​​the flatness distribution map to the corresponding area of ​​the test disk, which is the area to be processed; S203, if 0<M≤INT(Ф / 5d-1), 0<N≤2INT(Ф / 2d-2), and L max < Ф / 2, then physically clear the area to be processed; if M> INT(Ф / 5d-1) or N> 2INT(Ф / 2d-2) or L max ≥Ф / 2, the area to be processed is chemically cleaned; wherein Ф is the diameter of the silicon carbide substrate, mm; d is the side length of the test cell on the flatness distribution diagram, mm; The physical cleaning method comprises the following steps: using a cleaning tape to adhere to the to-be-treated area of ​​the test disc to remove dirt and using a clean brush to clean the gaps in the to-be-treated area; The chemical cleaning method comprises the following steps: using alkaline cleaning liquid to scrub and wash the area to be treated, using the alkaline cleaning liquid to scrub and wash the entire surface of the test disk, inverting the test disk and immersing it in water for ultrasonic cleaning, and drying it with nitrogen to obtain a clean test disk.

2. The method for removing high points of a silicon carbide substrate flatness test plate according to claim 1, characterized in that: In S1, the preset angle is 90°~180°.

3. The method for removing high points of a silicon carbide substrate flatness test plate according to claim 1, characterized in that: The physical cleaning method specifically includes the following steps: covering the to-be-treated area of ​​the test disc with a cleaning tape, cleaning the gaps in the to-be-treated area with a clean brush after removing the cleaning tape, and finally covering the to-be-treated area with the cleaning tape again, removing the cleaning tape, and obtaining a clean test disc.

4. The method for removing high points of a silicon carbide substrate flatness test plate according to claim 3, characterized in that: In S203, the cleaning tape is a polyethylene tape with an ISO grade of 3 to 6; and the width of the cleaning tape is greater than the stripe spacing of the test disk.

5. The method for removing high points of a silicon carbide substrate flatness test plate according to claim 3, characterized in that: In S203, a clean soft brush is used to clean the test disk along the stripes from the inside to the outside in a clockwise or counterclockwise direction.

6. The method for removing high points of a silicon carbide substrate flatness test plate according to claim 1, characterized in that: In S203, the alkaline cleaning solution includes the following components in mass fractions: 2% to 5% sodium bicarbonate, 1% to 3% sodium lauryl sulfate, 1% to 3% dodecyl dimethyl amine oxide, 3% to 7% coconut oil fatty acid diethanolamide, 0.05% to 0.2% sodium benzoate, and the balance is water.

7. The method for removing high points of a silicon carbide substrate flatness test plate according to claim 1, characterized in that: In S203, during the scrubbing, the scrubbing direction is from the inside to the outside along the texture of the test disk, and the scrubbing is performed in a clockwise or counterclockwise direction, and the scrubbing time is 5 minutes to 10 minutes.

8. The method for removing high points of a silicon carbide substrate flatness test plate according to claim 1, characterized in that: In S203, during water washing, the test plate is placed vertically and water is washed from top to bottom.

9. The method for removing high points of a silicon carbide substrate flatness test plate according to claim 1, characterized in that: In S203, the ultrasonic cleaning steps are specifically as follows: firstly ultrasonically clean at 50kHZ-70kHZ for 5min-10min, then ultrasonically clean at 70kHZ-90kHZ for 5min-10min, and finally ultrasonically clean at 100kHZ-120kHZ for 5min-10min.

10. The method for removing high points of a silicon carbide substrate flatness test plate according to claim 1, characterized in that: In S203, the purity of the nitrogen is ≥99.99%.

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