Preparation method of semi-insulating silicon carbide substrate

Abstract

The invention relates to the technical field of semiconductor materials, in particular to a preparation method of a semi-insulating silicon carbide substrate, which comprises the following steps: mixing high-purity silicon powder and carbon powder according to a preset proportion to synthesize silicon carbide particles; performing crystal growth to obtain a silicon carbide crystal ingot; cutting, grinding and polishing the silicon carbide crystal ingot to obtain a silicon carbide single crystal substrate; and carrying out high-temperature annealing and impurity removal treatment on the silicon carbide single crystal substrate to obtain the high-purity semi-insulating silicon carbide substrate. Wherein in the cutting process, the silicon carbide crystal ingot is cut after being subjected to pre-annealing treatment; contact pressure data, temperature data, cutting speed data, cooling liquid flow and integrity data in the cutting process are collected, then the optimal contact pressure and the optimal cutting temperature are determined, and therefore the adjusting mode of cutting parameters is determined. The cutting quality is effectively improved, and the cutting time is shortened.

Description

Technical Field

[0001] The present invention relates to the technical field of semiconductor materials, and in particular to a method for preparing a semi-insulating silicon carbide substrate. Background Art

[0002] Semi-insulating silicon carbide substrates have high resistivity, high thermal conductivity and wide bandgap characteristics, which can prevent current leakage in the substrate, withstand harsh environments such as high temperature and high pressure, and ensure the stability and reliability of the device. Semi-insulating silicon carbide substrates are often used in the fields of optoelectronics, 5G communications, and national defense.

[0003] In the prior art, the preparation of semi-insulating silicon carbide substrates often requires cutting of silicon carbide ingots. Due to the high hardness and brittleness of silicon carbide ingots, silicon carbide substrates are prone to cracking during the cutting process and the cutting time is long. Therefore, in order to reduce the risk of cracking and shorten the cutting time, the cutting parameters can be precisely controlled to ensure the stability and uniformity of the cutting process and to ensure the quality and performance of the final product.

[0004] Therefore, the present invention provides a method for preparing a semi-insulating silicon carbide substrate to solve the problem that the silicon carbide substrate is easy to crack during the cutting process and the cutting time is long. Summary of the invention

[0005] To this end, the present invention provides a method for preparing a semi-insulating silicon carbide substrate, so as to overcome the problems in the prior art that the silicon carbide substrate is prone to cracking during the cutting process and the cutting time is long.

[0006] To achieve the above object, the present invention provides a method for preparing a semi-insulating silicon carbide substrate, comprising:

[0007] Step S1, mixing high-purity silicon powder and carbon powder in a preset ratio to synthesize silicon carbide particles;

[0008] Step S2, loading the silicon carbide particles into a crucible, and moving the crucible into a crystal growth device for crystal growth to obtain a silicon carbide ingot;

[0009] Step S3, cutting, grinding and polishing the silicon carbide ingot to obtain a silicon carbide single crystal substrate;

[0010] Step S4, performing high temperature annealing and impurity removal treatment on the silicon carbide single crystal substrate to obtain a high-purity semi-insulating silicon carbide substrate;

[0011] Among them, the cutting process includes:

[0012] Step S31, pre-annealing the silicon carbide ingot and cutting the silicon carbide ingot;

[0013] Step S32, collecting contact pressure data between the cutting tool and the silicon carbide ingot during the cutting process, temperature data of the cutting area, cutting speed data, coolant flow rate, and integrity data of several wafers after cutting, wherein the integrity data includes the number of cracks and the incision width;

[0014] Step S33, determining an optimal contact pressure according to the contact pressure data and the integrity data, and determining an optimal cutting temperature according to the temperature data and the integrity data;

[0015] Step S34, determining a method for adjusting the cutting parameters according to the optimal contact pressure and the optimal cutting temperature;

[0016] Step S35, cutting the silicon carbide ingot according to the adjusted cutting parameters.

[0017] Furthermore, in step S31, it includes:

[0018] Determine the annealing temperature and annealing time according to the residual stress inside the silicon carbide ingot;

[0019] The silicon carbide ingot is pre-annealed according to the annealing temperature and annealing time.

[0020] Furthermore, an X-ray diffraction pattern of the silicon carbide ingot is collected, diffraction data is determined according to the X-ray diffraction pattern, and the residual stress is determined according to the diffraction data, wherein the diffraction data includes a diffraction peak position and an intensity change.

[0021] Furthermore, the annealing time is determined according to the annealing temperature and the residual stress.

[0022] Further, in step S33, determining the optimal contact pressure according to the contact pressure data and the integrity data includes:

[0023] determining a pressure-crack function between the crack data and the contact pressure based on the crack data and the contact pressure data;

[0024] Determining a pressure-notch function between the notch width and the contact pressure based on the notch width and the contact pressure data;

[0025] A first comprehensive optimization objective function is constructed according to the first weight, the pressure-crack function, the second weight, and the pressure-notch function to determine the optimal contact pressure.

[0026] Further, in step S33, the optimal cutting temperature is determined according to the temperature data and the integrity data, including:

[0027] determining a temperature-crack function between the crack data and the temperature data based on the crack data and the temperature data;

[0028] Determining a temperature-notch function between the notch width and the temperature data according to the notch width and the temperature data;

[0029] A second comprehensive optimization objective function is constructed according to the third weight, the temperature-crack function, the fourth weight, and the temperature-cut function to determine the optimal cutting temperature.

[0030] Furthermore, in step S4, determining the adjustment method of the cutting parameters includes:

[0031] If the pressure data is greater than or less than the optimal contact pressure, the cutting speed between the cutting tool and the silicon carbide ingot is adjusted.

[0032] Further, determining the adjustment amount of the cutting speed includes:

[0033] determining a first correlation coefficient based on the pressure data and the cutting speed data;

[0034] Determine a pressure difference according to the pressure data and an optimal contact pressure;

[0035] The adjustment amount of the cutting speed is determined according to the pressure difference and the first correlation coefficient.

[0036] Furthermore, in step S4, determining the adjustment method of the cutting parameters includes:

[0037] If the temperature data is greater than or less than the optimal cutting temperature, the coolant flow rate during the cutting process is adjusted.

[0038] Further, determining the adjustment amount of the coolant flow rate includes:

[0039] determining a second correlation coefficient based on the coolant flow rate and temperature data;

[0040] Determine the temperature difference based on the temperature data and the optimal cutting temperature;

[0041] The adjustment amount of the coolant flow is determined according to the temperature difference and the second correlation coefficient.

[0042] Compared with the prior art, the beneficial effect of the present invention is that by pre-annealing the silicon carbide ingot and accurately collecting a number of key data during the cutting process, the optimal cutting parameters (including contact pressure and cutting temperature) can be accurately determined, thereby optimizing the cutting process, improving the cutting quality and integrity of the silicon carbide single crystal substrate, reducing the problems of cracks and excessive incisions, and ensuring the preparation efficiency and quality of the final product.

[0043] Furthermore, the present invention performs pre-annealing on the silicon carbide ingot before cutting, and determines the annealing time and annealing temperature according to the residual stress in the silicon carbide ingot, thereby further releasing the residual stress inside the silicon carbide ingot, reducing the breakage rate during the cutting process, improving the cutting quality and integrity of the silicon carbide single crystal substrate, reducing the problems of cracks and excessive incisions, and ensuring the preparation efficiency and quality of the final product.

[0044] Furthermore, the present invention determines the optimal contact pressure based on the contact pressure data and the integrity data, and determines the optimal cutting temperature based on the temperature data and the integrity data, so as to further optimize the cutting parameters, improve the cutting quality and integrity of the silicon carbide single crystal substrate, reduce the problems of cracks and excessive incisions, and ensure the preparation efficiency and quality of the final product.

[0045] Furthermore, the present invention adjusts the cutting speed between the cutting tool and the silicon carbide ingot according to the comparison result between the pressure data and the optimal contact pressure, thereby ensuring the contact pressure between the cutting tool and the silicon carbide ingot, thereby optimizing the cutting process, improving the cutting quality and integrity of the silicon carbide single crystal substrate, reducing the problems of cracks and excessive incisions, and ensuring the preparation efficiency and quality of the final product.

[0046] Furthermore, the present invention adjusts the coolant flow rate when the cutting tool cuts the silicon carbide ingot according to the comparison result of the temperature data and the optimal cutting temperature, thereby preventing thermal deformation and thermal damage of the silicon carbide ingot caused by excessive temperature, thereby optimizing the cutting process, improving the cutting quality and integrity of the silicon carbide single crystal substrate, reducing the problems of cracks and excessive incisions, and ensuring the preparation efficiency and quality of the final product. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Figure 1 This is a flow chart of a method for preparing a semi-insulating silicon carbide substrate according to an embodiment of the present invention;

[0048] Figure 2 A flow chart of determining a method for adjusting cutting parameters according to an embodiment of the present invention;

[0049] Figure 3 This is a flow chart of pre-annealing a silicon carbide ingot according to an embodiment of the present invention;

[0050] Figure 4 Flowchart for determining optimal contact pressure for an embodiment of the present invention. DETAILED DESCRIPTION

[0051] In order to make the objects and advantages of the present invention more clearly understood, the present invention is further described below in conjunction with 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.

[0052] The preferred embodiments of the present invention are described below with reference to the accompanying drawings. It should be understood by those skilled in the art that these embodiments are only used to explain the technical principles of the present invention and are not intended to limit the protection scope of the present invention.

[0053] It should be noted that, in the description of the present invention, terms such as "up", "down", "left", "right", "inside" and "outside" indicating directions or positional relationships are based on the directions or positional relationships shown in the drawings. This is merely for the convenience of description and does not indicate or imply that the device or element must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it cannot be understood as a limitation on the present invention.

[0054] In addition, it should be noted that in the description of the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For those skilled in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0055] See also Figure 1-2 As shown, Figure 1 The flowchart of a method for preparing a semi-insulating silicon carbide substrate according to an embodiment of the present invention is as follows. Figure 2 The present invention is a flowchart for determining a method for adjusting cutting parameters according to an embodiment of the present invention; specifically, the present invention provides a method for preparing a semi-insulating silicon carbide substrate, comprising:

[0056] Step S1, mixing high-purity silicon powder and carbon powder in a preset ratio to synthesize silicon carbide particles;

[0057] Step S2, loading the silicon carbide particles into a crucible, and moving the crucible into a crystal growth device for crystal growth to obtain a silicon carbide ingot;

[0058] Step S3, cutting, grinding and polishing the silicon carbide ingot to obtain a silicon carbide single crystal substrate;

[0059] Step S4, performing high temperature annealing and impurity removal treatment on the silicon carbide single crystal substrate to obtain a high-purity semi-insulating silicon carbide substrate;

[0060] Among them, the cutting process includes:

[0061] Step S31, pre-annealing the silicon carbide ingot and cutting the silicon carbide ingot;

[0062] Step S32, collecting contact pressure data between the cutting tool and the silicon carbide ingot during the cutting process, temperature data of the cutting area, cutting speed data, coolant flow rate, and integrity data of several wafers after cutting, wherein the integrity data includes the number of cracks and the incision width;

[0063] Step S33, determining an optimal contact pressure according to the contact pressure data and the integrity data, and determining an optimal cutting temperature according to the temperature data and the integrity data;

[0064] Step S34, determining a method for adjusting the cutting parameters according to the optimal contact pressure and the optimal cutting temperature;

[0065] Step S35, cutting the silicon carbide ingot according to the adjusted cutting parameters.

[0066] It is understandable that the silicon carbide substrate is prone to cracking during the cutting process and the cutting time is long. Therefore, in order to reduce the risk of cracking and shorten the cutting time, the optimal contact pressure and optimal cutting temperature between the cutting tool and the silicon carbide ingot are accurately determined, and then the adjustment method of the cutting parameters is determined to ensure the cutting quality.

[0067] In a specific embodiment, the process of preparing a high-purity semi-insulating silicon carbide substrate is as follows: high-purity silicon powder and carbon powder are selected as raw materials, and the purity of the raw materials is usually above 99.999%. The high-purity silicon powder and carbon powder are uniformly mixed in a preset ratio of 1:1, and then synthesized at a high temperature (such as above 2000°C) and specific reaction conditions to generate silicon carbide particles. The synthesized silicon carbide particles are then loaded into a crucible and then moved to a crystal growth device. In a closed growth chamber, the silicon carbide powder is sublimated by heating to produce a material containing Si, Si 2 C. SiC 2 By controlling the temperature field and the transmission of the reaction gas, the sublimated components are recrystallized on the surface of the seed crystal, thereby growing a silicon carbide ingot. Subsequently, a diamond wire is used to cut the silicon carbide ingot into thin slices of the required thickness, i.e., silicon carbide single crystal substrates, which are further ground, polished, annealed at high temperature, and impurities are removed to improve the purity and quality of the silicon carbide single crystal substrates.

[0068] The present invention performs pre-annealing treatment on the silicon carbide ingot and accurately collects multiple key data during the cutting process, so as to accurately determine the optimal cutting parameters (including contact pressure and cutting temperature), thereby optimizing the cutting process, improving the cutting quality and integrity of the silicon carbide single crystal substrate, reducing the problems of cracks and excessive incisions, and ensuring the preparation efficiency and quality of the final product.

[0069] See also Figure 3 As shown, Figure 3This is a flow chart of pre-annealing a silicon carbide ingot according to an embodiment of the present invention. Specifically, in step S31, it includes:

[0070] Step S311, determining annealing temperature and annealing time according to residual stress inside the silicon carbide ingot;

[0071] Step S312: pre-annealing the silicon carbide ingot according to the annealing temperature and annealing time.

[0072] It is understandable that residual stress will be generated in the growth process of silicon carbide ingots, which may cause wafer breakage or cracks during the cutting process. Pre-annealing can release the residual stress inside the silicon carbide ingot, thereby reducing the breakage rate during the cutting process.

[0073] Specifically, in step S311, an X-ray diffraction pattern of the silicon carbide ingot is collected, diffraction data is determined according to the X-ray diffraction pattern, and the residual stress is determined according to the diffraction data, wherein the diffraction data includes a diffraction peak position and an intensity change.

[0074] In a specific embodiment, XRD (X-ray diffraction) is used to detect silicon carbide ingots, and an X-ray diffraction pattern is obtained to characterize the structure of the silicon carbide ingot and its changing pattern. After the X-ray diffraction pattern is smoothed and denoised, the lattice structure and stress state inside the silicon carbide ingot can be preliminarily determined by observing the position and intensity changes of the diffraction peaks in the diffraction pattern. If the position of the diffraction peak shifts or the intensity changes, it indicates that there is residual stress inside the silicon carbide ingot. The residual stress can be calculated by professional XRD software.

[0075] Specifically, the annealing time is determined according to the annealing temperature and the residual stress.

[0076] In a specific embodiment, the annealing temperature is determined according to the residual stress inside the silicon carbide ingot. If the residual stress is greater than 20MPa to 40MPa, the annealing temperature is determined to be 1800°C to 1850°C. Preferably, the annealing temperature is 1810°C. The annealing time is 1h to 3h. Preferably, the annealing time is 2h. The range and preferred value of the annealing temperature and return time can be determined according to actual conditions, and are not specifically limited here and will not be repeated.

[0077] The present invention performs a pre-annealing treatment on the silicon carbide ingot before cutting, and determines the annealing time and annealing temperature according to the residual stress in the silicon carbide ingot, thereby further releasing the residual stress inside the silicon carbide ingot, reducing the breakage rate during the cutting process, improving the cutting quality and integrity of the silicon carbide single crystal substrate, reducing the problems of cracks and excessive incisions, and ensuring the preparation efficiency and quality of the final product.

[0078] See also Figure 4 As shown, Figure 4 The flowchart of determining the optimal contact pressure according to the embodiment of the present invention is as follows. Specifically, in step S33, the optimal contact pressure is determined according to the contact pressure data and the integrity data, including:

[0079] Step S331, determining a pressure-crack function between the crack data and the contact pressure according to the crack data and the contact pressure data;

[0080] Step S332, determining a pressure-incision function between the incision width and the contact pressure according to the incision width and the contact pressure data;

[0081] Step S333, constructing a first comprehensive optimization objective function according to the first weight, the pressure-crack function, the second weight, and the pressure-notch function to determine the optimal contact pressure.

[0082] In a specific embodiment, the pressure-crack function and the pressure-notch function can be obtained by data fitting, and the minimum number of cracks and the minimum notch width are used as limiting conditions. The optimal contact pressure is determined according to the limiting conditions, the pressure-crack function and the pressure-notch function. The first weight is the influence of the contact pressure on the number of wafer cracks, and the second weight is the influence of the contact pressure relative to the wafer notch width. The optimal contact pressure can be obtained by solving the minimum value of the first comprehensive optimization objective function according to the limiting conditions. Preferably, the first weight is 0.5, the second weight is 0.5, and the minimum number of cracks is in the range of 0 to 2, preferably, the minimum number of cracks is 1. The minimum notch width is in the range of 10μm to 30μm, preferably, the minimum notch width is 20μm. In implementation, the value range and preferred value of the first weight, the second weight, the minimum number of cracks, and the minimum notch width can be determined according to actual conditions, and will not be repeated here.

[0083] Specifically, in step S33, the optimal cutting temperature is determined according to the temperature data and the integrity data, including:

[0084] Step S334, determining a temperature-crack function between the crack data and the temperature data according to the crack data and the temperature data;

[0085] Step S335, determining a temperature-notch function between the notch width and the temperature data according to the notch width and the temperature data;

[0086] Step S336, constructing a second comprehensive optimization objective function according to the third weight, the temperature-crack function, the fourth weight, and the temperature-cut function to determine the optimal cutting temperature.

[0087] In a specific embodiment, the temperature-crack function and the temperature-notch function can be obtained by data fitting, and the minimum number of cracks and the minimum notch width are used as limiting conditions. The optimal cutting temperature is determined according to the limiting conditions and the temperature-crack function and the temperature-notch function. The third weight is the influence of the temperature data on the number of wafer cracks, and the fourth weight is the influence of the temperature data on the wafer notch width. The optimal contact pressure can be obtained by solving the minimum value of the second comprehensive optimization objective function according to the limiting conditions. Preferably, the third weight is 0.5, the fourth weight is 0.5, and the minimum number of cracks is in the range of 0 to 2, preferably, the minimum number of cracks is 1. The minimum notch width is in the range of 10μm to 30μm, preferably, the minimum notch width is 20μm. In implementation, the value range and preferred value of the third weight, the fourth weight, the minimum number of cracks, and the minimum notch width can be determined according to actual conditions, and will not be repeated here.

[0088] The present invention determines the optimal contact pressure according to the contact pressure data and the integrity data, and determines the optimal cutting temperature according to the temperature data and the integrity data, so as to further optimize the cutting parameters, improve the cutting quality and integrity of the silicon carbide single crystal substrate, reduce the problems of cracks and excessive incisions, and ensure the preparation efficiency and quality of the final product.

[0089] Specifically, in step S4, determining the adjustment method of the cutting parameters includes:

[0090] If the pressure data is greater than or less than the optimal contact pressure, the cutting speed between the cutting tool and the silicon carbide ingot is adjusted.

[0091] It is understandable that if the cutting speed changes, the contact pressure between the cutting tool and the silicon carbide ingot will change, which will affect the cutting depth and the cutting effect. Therefore, the cutting speed between the cutting tool and the silicon carbide ingot is adjusted according to the comparison result between the pressure data and the optimal contact pressure.

[0092] Specifically, determine the adjustment amount of cutting speed, including:

[0093] determining a first correlation coefficient based on the pressure data and the cutting speed data;

[0094] Determine a pressure difference according to the pressure data and an optimal contact pressure;

[0095] The adjustment amount of the cutting speed is determined according to the pressure difference and the first correlation coefficient.

[0096] In a specific embodiment, the first correlation coefficient between the pressure data and the cutting speed data can be obtained by the Pearson correlation coefficient calculation formula, the pressure difference is the difference between the pressure data and the optimal contact pressure, and the adjustment amount of the cutting speed is the product of the first correlation coefficient and the pressure difference. In implementation, the adjustment amount of the cutting speed can be determined according to actual conditions, which is not specifically limited here and will not be repeated.

[0097] The present invention adjusts the cutting speed between the cutting tool and the silicon carbide ingot according to the comparison result between the pressure data and the optimal contact pressure, thereby ensuring the contact pressure between the cutting tool and the silicon carbide ingot, thereby optimizing the cutting process, improving the cutting quality and integrity of the silicon carbide single crystal substrate, reducing the problems of cracks and excessive incisions, and ensuring the preparation efficiency and quality of the final product.

[0098] Specifically, in step S4, determining the adjustment method of the cutting parameters includes:

[0099] If the temperature data is greater than or less than the optimal cutting temperature, the coolant flow rate during the cutting process is adjusted.

[0100] Specifically, determine the amount of adjustment to the coolant flow, including:

[0101] determining a second correlation coefficient based on the coolant flow rate and temperature data;

[0102] Determine the temperature difference based on the temperature data and the optimal cutting temperature;

[0103] The adjustment amount of the coolant flow is determined according to the temperature difference and the second correlation coefficient.

[0104] It is understandable that silicon carbide has a high hardness and will generate a lot of heat due to friction during the cutting process. Without coolant, the wafer will overheat, affecting the cutting quality or even damaging the wafer. Therefore, the adjustment amount of the coolant flow is determined based on the temperature data and the optimal cutting temperature data to help reduce the temperature of the cutting area and prevent thermal deformation and thermal damage of the silicon carbide ingot caused by excessive temperature.

[0105] In a specific embodiment, the second correlation coefficient between the coolant flow rate and the temperature data can be obtained by the Pearson correlation coefficient calculation formula, the temperature difference is the difference between the temperature data and the optimal cutting temperature, and the adjustment amount of the coolant flow rate is the product of the second correlation coefficient and the temperature difference. In implementation, the adjustment amount of the coolant flow rate can be determined according to actual conditions, which is not specifically limited here and will not be repeated.

[0106] The present invention adjusts the coolant flow rate when the cutting tool cuts the silicon carbide ingot according to the comparison result of temperature data and the optimal cutting temperature, thereby preventing thermal deformation and thermal damage of the silicon carbide ingot caused by excessive temperature, thereby optimizing the cutting process, improving the cutting quality and integrity of the silicon carbide single crystal substrate, reducing the problems of cracks and excessive incisions, and ensuring the preparation efficiency and quality of the final product.

[0107] So far, the technical solutions of the present invention have been described in conjunction with the preferred embodiments shown in the accompanying drawings. However, it is easy for those skilled in the art to understand that the protection scope of the present invention is obviously not limited to these specific embodiments. Without departing from the principle of the present invention, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after these changes or substitutions will fall within the protection scope of the present invention.

Claims

1. A method for preparing a semi-insulating silicon carbide substrate, characterized in that: include: Step S1, mixing high-purity silicon powder and carbon powder in a preset ratio to synthesize silicon carbide particles; Step S2, loading the silicon carbide particles into a crucible, and moving the crucible into a crystal growth device for crystal growth to obtain a silicon carbide ingot; Step S3, cutting, grinding and polishing the silicon carbide ingot to obtain a silicon carbide single crystal substrate; Step S4, performing high temperature annealing and impurity removal treatment on the silicon carbide single crystal substrate to obtain a high-purity semi-insulating silicon carbide substrate; Among them, the cutting process includes: Step S31, pre-annealing the silicon carbide ingot and cutting the silicon carbide ingot; Step S32, collecting contact pressure data between the cutting tool and the silicon carbide ingot during the cutting process, temperature data of the cutting area, cutting speed data, coolant flow rate, and integrity data of several wafers after cutting, wherein the integrity data includes the number of cracks and the incision width; Step S33, determining an optimal contact pressure according to the contact pressure data and the integrity data, and determining an optimal cutting temperature according to the temperature data and the integrity data; Step S34, determining a method for adjusting the cutting parameters according to the optimal contact pressure and the optimal cutting temperature; Step S35, cutting the silicon carbide ingot according to the adjusted cutting parameters.

2. The method for preparing a semi-insulating silicon carbide substrate according to claim 1, characterized in that: In step S31, it includes: Determine the annealing temperature and annealing time according to the residual stress inside the silicon carbide ingot; The silicon carbide ingot is pre-annealed according to the annealing temperature and annealing time.

3. The method for preparing a semi-insulating silicon carbide substrate according to claim 2, characterized in that: include: An X-ray diffraction pattern of the silicon carbide ingot is collected, diffraction data is determined according to the X-ray diffraction pattern, and the residual stress is determined according to the diffraction data, wherein the diffraction data includes a diffraction peak position and an intensity change.

4. The method for preparing a semi-insulating silicon carbide substrate according to claim 3, characterized in that: The annealing time is determined according to the annealing temperature and the residual stress.

5. The method for preparing a semi-insulating silicon carbide substrate according to claim 1, characterized in that: In step S33, determining the optimal contact pressure according to the contact pressure data and the integrity data includes: determining a pressure-crack function between the crack data and the contact pressure based on the crack data and the contact pressure data; Determining a pressure-notch function between the notch width and the contact pressure based on the notch width and the contact pressure data; A first comprehensive optimization objective function is constructed according to the first weight, the pressure-crack function, the second weight, and the pressure-notch function to determine the optimal contact pressure.

6. The method for preparing a semi-insulating silicon carbide substrate according to claim 5, characterized in that: In step S33, the optimal cutting temperature is determined according to the temperature data and the integrity data, including: determining a temperature-crack function between the crack data and the temperature data based on the crack data and the temperature data; Determining a temperature-notch function between the notch width and the temperature data according to the notch width and the temperature data; A second comprehensive optimization objective function is constructed according to the third weight, the temperature-crack function, the fourth weight, and the temperature-cut function to determine the optimal cutting temperature.

7. The method for preparing a semi-insulating silicon carbide substrate according to claim 5, characterized in that: In step S4, determining the adjustment method of the cutting parameters includes: If the pressure data is greater than or less than the optimal contact pressure, the cutting speed between the cutting tool and the silicon carbide ingot is adjusted.

8. The method for preparing a semi-insulating silicon carbide substrate according to claim 7, characterized in that: Determine the amount of adjustment for cutting speed, including: determining a first correlation coefficient based on the pressure data and the cutting speed data; Determining a pressure difference according to the pressure data and an optimal contact pressure; The adjustment amount of the cutting speed is determined according to the pressure difference and the first correlation coefficient.

9. The method for preparing a semi-insulating silicon carbide substrate according to claim 7, characterized in that: In step S4, determining the adjustment method of the cutting parameters includes: If the temperature data is greater than or less than the optimal cutting temperature, the coolant flow rate during the cutting process is adjusted.

10. The method for preparing a semi-insulating silicon carbide substrate according to claim 9, characterized in that: Determine adjustments to coolant flow, including: determining a second correlation coefficient based on the coolant flow rate and temperature data; Determine the temperature difference based on the temperature data and the optimal cutting temperature; The adjustment amount of the coolant flow is determined according to the temperature difference and the second correlation coefficient.

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