A method of producing a silicon carbide substrate

Abstract

The present application relates to the technical field of substrate preparation, and particularly relates to a preparation method of silicon carbide substrate, comprising the following steps: detecting the surface of prepared silicon carbide crystal bar to obtain the surface roughness of the silicon carbide crystal bar and the diameter of the crystal bar; determining the initial cutting mode of the silicon carbide crystal bar according to the surface roughness, wherein the initial cutting mode comprises a first cutting mode and a second cutting mode; cutting the silicon carbide crystal bar according to the initial cutting mode to obtain a silicon carbide wafer; determining grinding parameters according to the cutting texture direction and the bending degree of the surface of the silicon carbide wafer; the grinding parameters comprise a grinding granularity and a grinding pressure; grinding the silicon carbide wafer according to the grinding parameters, and polishing the ground silicon carbide wafer to obtain the silicon carbide substrate. The present application can improve the production efficiency and the production quality of the silicon carbide substrate.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of substrate preparation, in particular to a preparation method of silicon carbide substrate. BACKGROUND

[0002] The device made of silicon carbide material has the characteristics of high temperature resistance, high pressure resistance, high frequency, high power, radiation resistance, etc., and also has the advantages of fast switching speed and high efficiency, which can greatly reduce product power consumption, improve energy conversion efficiency and reduce product volume. At present, silicon carbide semiconductors are widely used in radio frequency fields represented by 5G communication, national defense and military industry, aerospace, and power electronic fields represented by new energy vehicles. The silicon carbide substrate prepared by using silicon carbide material has the characteristics of large band gap, high thermal conductivity, high critical breakdown field strength, and high electron saturation drift rate. These characteristics make its application performance under the conditions of high temperature, high pressure, high frequency, and high power better than that of silicon substrate, and it is widely used in the manufacture of radio frequency devices and power devices. The global silicon carbide substrate market has shown a significant growth trend in recent years, and is expected to achieve rapid growth in the next few years.

[0003] The preparation process of silicon carbide substrate includes raw material synthesis, crystal growth, crystal ingot processing, crystal bar cutting, cutting piece grinding, ground piece polishing, and polished piece cleaning. At present, in order to improve the performance of silicon carbide substrate, optimization is mostly carried out in raw material synthesis and crystal growth. However, crystal bar cutting and cutting piece grinding also have a great influence on the performance of silicon carbide substrate. If there is damage on the surface of the substrate after cutting and grinding, it will directly spread to the surface of the epitaxial wafer in the form of triangular defects, forming a large number of unqualified areas. These unqualified areas will greatly reduce the yield of chips in the subsequent chip manufacturing process, and are the primary factor affecting the yield of chips.

[0004] Chinese Patent Publication No. CN109545680B discloses a rapid preparation method of high flatness and low damage single crystal silicon carbide substrate, which comprises the following steps: full solidified abrasive processing of single crystal silicon carbide, and then chemical mechanical polishing treatment to obtain the high flatness and low damage single crystal silicon carbide substrate; wherein the solidified abrasive processing includes wire cutting and grinding wheel grinding, solidified abrasive particles are fixed on the cutting wire, and solidified abrasive particles are fixed on the grinding wheel.

[0005] It can be seen from the above that the above-mentioned application has the following problems: the preparation process is relatively complex, the influence of the surface roughness of the silicon carbide crystal bar on the cutting and grinding process is not considered, the production efficiency is relatively low, and the quality of the silicon carbide substrate is not high. SUMMARY

[0006] To this end, the present application provides a preparation method of silicon carbide substrate to overcome the problems of complicated preparation process in prior art, low production efficiency, and no consideration of the influence of surface roughness of silicon carbide crystal bar on cutting and grinding process, and low quality of silicon carbide substrate.

[0007] To achieve the above-mentioned purpose, the present application provides a preparation method of silicon carbide substrate, comprising:

[0008] Step S1, detecting the surface of the prepared silicon carbide crystal bar to obtain the surface roughness of the silicon carbide crystal bar and the diameter of the crystal bar; wherein the surface roughness includes a first roughness corresponding to a first surface and a second roughness corresponding to a second surface;

[0009] Step S2, determining the initial cutting mode of the silicon carbide crystal bar according to the surface roughness, including a first cutting mode and a second cutting mode;

[0010] Wherein, under the first condition, the first cutting mode is used, and the first cutting parameter corresponding to the first cutting mode is determined according to the diameter of the crystal bar, the first cutting parameter including a first cutting point and a first cutting speed;

[0011] Under the second condition, the second cutting mode is used, and the second cutting parameter is determined according to the surface roughness and the diameter of the crystal bar, the second cutting parameter including a second cutting point, a second cutting speed, an initial cutting depth, and a third cutting speed;

[0012] Step S3, cutting the silicon carbide crystal bar according to the initial cutting mode to obtain a silicon carbide wafer;

[0013] Step S4, determining the grinding parameter according to the cutting texture direction and the bending degree of the surface of the silicon carbide wafer; the grinding parameter including the grinding granularity and the grinding pressure;

[0014] Step S5, grinding the silicon carbide wafer according to the grinding parameter, and polishing the ground silicon carbide wafer to obtain a silicon carbide substrate.

[0015] Further, in the step S2, the initial cutting mode of the silicon carbide crystal bar is determined, including:

[0016] If the first roughness and the second roughness are both less than a preset roughness threshold, and the difference between the first roughness and the second roughness is less than a first preset difference, it is determined that the first condition is met, and the first cutting mode is used;

[0017] If the first roughness and the second roughness are both less than a preset roughness threshold, and a difference between the first roughness and the second roughness is greater than or equal to a first preset difference, it is determined that the second condition is met, and the second cutting mode is used.

[0018] Further, in the step S2, the first cutting mode includes:

[0019] In the cutting process, the cutting device takes the first cutting point as an initial cutting point, and cuts at a first cutting speed, to complete the cutting process of the silicon carbide crystal bar; wherein the obtained silicon carbide wafer takes the second surface as a bottom surface.

[0020] Further, in the step S2, the second cutting mode divides the silicon carbide crystal bar into a first cutting part and a second cutting part;

[0021] In the cutting process of the first cutting part, the cutting device takes the second cutting point as an initial cutting point, and the cutting depth is an initial cutting depth, and starts to rotate and cut at a second cutting speed, to complete the cutting process of the first cutting part;

[0022] In the cutting process of the second cutting part, the cutting device cuts at a third cutting speed, to complete the cutting process of the second cutting part;

[0023] In the cutting process, the cutting device sequentially completes the cutting of the first cutting part and the second cutting part, to complete the cutting process of the silicon carbide crystal bar.

[0024] Further, in the step S2, the first cutting parameter is determined by the following steps:

[0025] Step S21, comparing the crystal bar diameter with a preset diameter threshold, and determining a first cutting coefficient according to the comparison result;

[0026] Step S22, determining a first cutting length according to the crystal bar diameter and the first cutting coefficient; wherein an arbitrary point on a circular arc with a first cutting length from the edge of the second surface on the first surface is a first cutting point;

[0027] Step S23, comparing the first cutting length with a preset cutting length, and determining the first cutting speed according to the comparison result and a standard cutting speed.

[0028] Further, in the step S2, the second cutting parameter is determined by the following steps:

[0029] Step S24, determining a second cutting coefficient according to the first roughness and the second roughness;

[0030] Step S25, determining a second cutting length according to the diameter of the crystal bar and the second cutting coefficient; wherein, any point on a circular arc with the second cutting length as the radius and the second surface edge as the center on the first surface is a second cutting point;

[0031] Step S26, comparing the second cutting length with a preset cutting length, and determining the second cutting speed according to the comparison result and a standard cutting speed;

[0032] Step S27, determining a third cutting coefficient according to the ratio of the first roughness and the second roughness, and determining the initial cutting depth according to the second cutting length and the third cutting coefficient;

[0033] Step S28, comparing the initial cutting depth with the diameter of the crystal bar, and determining the third cutting speed according to the comparison result and a standard cutting speed.

[0034] Further, in the step S4, the grinding parameters are determined according to the cutting texture direction and the bending degree of the surface of the silicon carbide wafer, including:

[0035] comparing the cutting texture direction with a preset cutting texture direction to determine whether the cutting texture direction conforms to the preset cutting texture direction;

[0036] If the cutting texture direction conforms to the preset cutting texture direction, the grinding granularity is set as a standard grinding granularity, and the grinding pressure is set as a standard grinding pressure.

[0037] If the cutting texture direction does not conform to the preset cutting texture direction, the grinding parameters are determined according to the bending degree.

[0038] Further, the grinding parameters determined according to the bending degree include:

[0039] comparing the bending degree with a standard bending degree to determine a first comparison value, and determining the grinding granularity according to the first comparison value and a standard grinding granularity, and determining the grinding pressure according to the first comparison value and a standard grinding pressure.

[0040] Further, in the step S2, if the first roughness and the second roughness are both greater than or equal to a preset roughness threshold, it is determined that a third condition is met, and a third cutting method is used.

[0041] Further, the third cutting method includes:

[0042] In the cutting process, the cutting device takes the third cutting point as the initial cutting point, and cuts at a standard cutting speed uniformly to complete the cutting process of the silicon carbide crystal bar.

[0043] Compared with the prior art, the present application has the beneficial effect that the present application determines the initial cutting mode of the silicon carbide crystal bar through the surface roughness of the silicon carbide crystal bar, which can reduce the influence of the surface roughness of the silicon carbide crystal bar on the cutting process, improve the production efficiency and the quality of the silicon carbide substrate. Since the cutting texture direction of the wafer surface will affect the material removal rate and surface roughness in the grinding process, and the bending degree of the wafer can affect the pressure distribution in the grinding process, thereby affecting the flatness of the entire wafer, determining the grinding parameters through the cutting texture direction and the bending degree of the silicon carbide wafer surface can further improve the quality of the silicon carbide substrate.

[0044] Further, the first roughness and the second roughness corresponding to the first cutting mode are both relatively small, and the difference between the two is also relatively small, indicating that the surface roughness distribution of the corresponding silicon carbide wafer is relatively uniform. By taking the first cutting point as the initial cutting point and cutting at a first cutting speed uniformly, the production efficiency can be improved.

[0045] Further, the first roughness corresponding to the second cutting mode is relatively small, but the difference between the two is relatively large, indicating that the surface roughness distribution of the corresponding silicon carbide wafer is not uniform enough. By dividing the silicon carbide crystal bar into a first cutting part and a second cutting part for cutting respectively, the cutting quality can be improved, thereby improving the quality of the silicon carbide substrate.

[0046] Further, the first cutting parameter is determined by the diameter of the crystal bar, and the second cutting parameter is determined by the surface roughness of the silicon carbide crystal bar and the diameter of the crystal bar, which can improve the cutting quality and production efficiency of each silicon carbide crystal bar.

[0047] Further, the first roughness and the second roughness are both relatively large, which will increase the friction in the cutting process. By taking the third cutting point as the initial cutting point and cutting at a standard cutting speed uniformly, the cutting quality of the silicon carbide crystal bar can be improved. BRIEF DESCRIPTION OF DRAWINGS

[0048] Figure 1 The flowchart of the preparation method of the silicon carbide substrate of the embodiment of the present application;

[0049] Figure 2 The flowchart of the preparation method of the silicon carbide substrate of the embodiment of the present application;

[0050] Figure 3Flow chart for determining the second cutting parameter for the embodiment of the present application;

[0051] Figure 4 Logic decision chart for determining the initial cutting mode for the embodiment of the present application;

[0052] Figure 5 Structure schematic diagram of the first cutting mode for the embodiment of the present application;

[0053] Figure 6 Structure schematic diagram of the second cutting mode for the embodiment of the present application;

[0054] In the figure: 1, silicon carbide crystal bar; 2, first surface; 3, second surface; 4, first cutting point; 5, second cutting point. DETAILED DESCRIPTION

[0055] In order to make the objects and advantages of the present application clearer, the present application will be further described below in conjunction with embodiments. It should be understood that the specific embodiments described herein merely serve the purpose of explaining the present application and are not intended to limit the present application.

[0056] The preferred embodiments of the present application will be described below with reference to the accompanying drawings. It should be understood by those skilled in the art that the embodiments merely serve the purpose of explaining the technical principles of the present application and are not intended to limit the protection scope of the present application.

[0057] It should be noted that, in the description of the present application, the terms indicating the direction or positional relationship such as "upper", "lower", "left", "right", "inner", "outer" and the like are based on the direction or positional relationship shown in the drawings, which is merely for the purpose of description and does not indicate or imply that the device or element must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present application.

[0058] In addition, it should also be noted that, in the description of the present application, unless otherwise explicitly specified and limited, the terms "mounting", "connecting", "connection" should be understood in a broad sense, for example, can be fixed connection, can also be detachable connection, or integrally connected; can be mechanical connection, can also be electrical connection; can be directly connected, can also be indirectly connected through an intermediate medium, can be the communication inside two elements. Those skilled in the art can understand the specific meaning of the above terms in the present application according to the specific circumstances.

[0059] Please refer to Figure 1 As shown in the figure, it is a flow chart of the preparation method of the silicon carbide substrate according to the embodiment of the present application; the embodiment of the present application provides a preparation method of a silicon carbide substrate, which comprises:

[0060] Step S1, detecting the surface of the prepared silicon carbide crystal rod to obtain the surface roughness of the silicon carbide crystal rod and the diameter of the crystal rod; wherein the surface roughness comprises a first roughness corresponding to a first surface and a second roughness corresponding to a second surface;

[0061] In implementation, the specific method or device for detecting the surface of the silicon carbide crystal rod is not limited, the surface roughness of the silicon carbide crystal rod can be directly measured by a roughness measuring instrument, and the diameter of the silicon carbide crystal rod can be measured by a laser diameter measuring instrument, which are all prior art and will not be described in detail.

[0062] Step S2, determining an initial cutting mode of the silicon carbide crystal rod according to the surface roughness, comprising a first cutting mode and a second cutting mode;

[0063] Under the first condition, the first cutting mode is used, and a first cutting parameter corresponding to the first cutting mode is determined according to the diameter of the crystal rod, the first cutting parameter comprising a first cutting point and a first cutting speed;

[0064] Under the second condition, the second cutting mode is used, and a second cutting parameter is determined according to the surface roughness and the diameter of the crystal rod, the second cutting parameter comprising a second cutting point, a second cutting speed, an initial cutting depth and a third cutting speed;

[0065] It should be noted that any method and device capable of cutting the silicon carbide crystal rod in the prior art, such as laser cutting, falls within the protection scope of the present application, and will not be described in detail.

[0066] Please refer to Figure 4 shown, which is a logic decision diagram for determining the initial cutting mode according to the embodiment of the present application; specifically, in the step S2, the initial cutting mode of the silicon carbide crystal rod is determined, comprising:

[0067] If the first roughness and the second roughness are both less than a preset roughness threshold, and the difference between the first roughness and the second roughness is less than a first preset difference, it is determined that the first condition is met, and the first cutting mode is used;

[0068] If the first roughness and the second roughness are both less than a preset roughness threshold, and the difference between the first roughness and the second roughness is greater than or equal to the first preset difference, it is determined that the second condition is met, and the second cutting mode is used.

[0069] In the implementation, the actual implementer can set the preset roughness threshold according to the actual situation or based on the average of the surface roughness of the silicon carbide wafer that passes the qualification test in the historical data, and preferably, the preset roughness threshold is set to a value range of 7nm-15nm; the actual implementer can set the first preset difference according to the actual situation or based on the average of the difference between the first roughness and the second roughness of the silicon carbide wafer that passes the qualification test in the historical data, and preferably, the first preset difference is set to a value range of 2nm-5nm.

[0070] Referring to Figure 5 As shown in the figure, it is a structural schematic diagram of the first cutting mode of the embodiment of the application; the figure includes a silicon carbide crystal bar 1, a first surface 2, a second surface 3 and a first cutting point 4.

[0071] Specifically, in the step S2, the first cutting mode includes:

[0072] In the cutting process, the cutting equipment takes the first cutting point as the initial cutting point and cuts at a first cutting speed, to complete the cutting process of the silicon carbide crystal bar; wherein the obtained silicon carbide wafer takes the second surface as the bottom surface.

[0073] The first roughness and the second roughness corresponding to the first cutting mode are both relatively small, and the difference between the two is also relatively small, indicating that the surface roughness distribution of the corresponding silicon carbide wafer is relatively uniform, and by taking the first cutting point as the initial cutting point and cutting at a first cutting speed, the production efficiency can be improved.

[0074] Referring to Figure 6 As shown in the figure, it is a structural schematic diagram of the second cutting mode of the embodiment of the application; the figure includes: a silicon carbide crystal bar 1, a first surface 2, a second surface 3, and a second cutting point 5.

[0075] Specifically, in the step S2, the second cutting mode divides the silicon carbide crystal bar into a first cutting part and a second cutting part;

[0076] In the cutting process of the first cutting part, the cutting equipment takes the second cutting point as the initial cutting point, and the cutting depth is the initial cutting depth, and starts to rotate and cut at a second cutting speed, to complete the cutting process of the first cutting part;

[0077] In the cutting process of the second cutting part, the cutting equipment cuts at a third cutting speed, to complete the cutting process of the second cutting part;

[0078] In the cutting process, the cutting equipment sequentially completes the cutting of the first cutting part and the second cutting part, to complete the cutting process of the silicon carbide crystal bar.

[0079] The second cutting mode corresponds to a first roughness which is smaller, but the difference between the two is larger, indicating that the surface roughness distribution of the corresponding silicon carbide wafer is not uniform enough. By dividing the silicon carbide crystal bar into a first cutting part and a second cutting part for cutting respectively, the cutting quality can be improved, thereby improving the quality of the silicon carbide substrate.

[0080] Please refer to Figure 2 As shown in the figure, it is a flowchart of determining the first cutting parameter according to an embodiment of the present application. Specifically, in the step S2, the first cutting parameter is determined by the following steps:

[0081] Step S21, compare the diameter of the crystal bar with the preset diameter threshold, and determine the first cutting coefficient according to the comparison result;

[0082] In implementation, the first cutting coefficient is determined according to the square of the ratio of the difference between the diameter of the crystal bar and the preset diameter threshold to the preset diameter threshold.

[0083] It should be noted that the actual implementer can set the preset diameter threshold based on the mean value of the diameter of the crystal bar corresponding to the silicon carbide wafer passing the qualification test in the historical data. Preferably, the preset diameter threshold is set to 101% to 110% of the standard diameter of the silicon carbide substrate in actual demand. For example, if the standard diameter of the silicon carbide substrate in actual demand is 8 inches (200 mm), the preset diameter threshold can be set to 202 mm to 220 mm.

[0084] Step S22, determine the first cutting length according to the diameter of the crystal bar and the first cutting coefficient; wherein any point on the circular arc with a first cutting length from the edge of the second surface on the first surface is a first cutting point;

[0085] In implementation, the first cutting length is determined according to the product of the diameter of the crystal bar and the first cutting coefficient.

[0086] Step S23, compare the first cutting length with the preset cutting length, and determine the first cutting speed according to the comparison result and the standard cutting speed.

[0087] In implementation, the first intermediate value is determined according to the ratio of the first cutting length to the preset cutting length, and the first cutting speed is determined according to the product of the first intermediate value and the standard cutting speed.

[0088] It should be noted that the actual implementer can set the preset cutting length based on the actual situation or based on the average value of the cutting speed of the silicon carbide wafer that passes the qualification test in the historical data, and preferably, the preset cutting length is set to 101% to 105% of the standard thickness of the silicon carbide substrate in actual demand, for example, the standard thickness corresponding to the actual demand of the silicon carbide substrate with a standard diameter of 8 inches (200 mm) is 500 μm, and the preset cutting length can be set to 505 μm to 525 μm.

[0089] Specifically, the actual implementer can determine the standard cutting speed based on the minimum value of the cutting speed of the silicon carbide wafer that passes the qualification test in the historical data, and preferably, the standard cutting speed can be set to 100 mm / s to 150 mm / s.

[0090] Referring to Figure 3 The flowchart shown in FIG. 2 is a flowchart of the process of determining the second cutting parameter according to an embodiment of the present application, and specifically, in step S2, the second cutting parameter is determined by the following steps:

[0091] In step S24, a second cutting coefficient is determined according to the first roughness and the second roughness.

[0092] In implementation, the second cutting coefficient is determined according to the square of the ratio of the difference between the first roughness and the second roughness to the second roughness.

[0093] In step S25, a second cutting length is determined according to the diameter of the crystal bar and the second cutting coefficient, and wherein any point on the circular arc with the second cutting length from the edge of the second surface on the first surface is a second cutting point.

[0094] In implementation, the second cutting length is determined according to the product of the diameter of the crystal bar and the second cutting coefficient.

[0095] In step S26, the second cutting length is compared with a preset cutting length, and the second cutting speed is determined according to the comparison result and the standard cutting speed.

[0096] In implementation, a second intermediate value is determined according to the ratio of the second cutting length to the preset cutting length, and the second cutting speed is determined according to the product of the second intermediate value and the standard cutting speed.

[0097] In step S27, a third cutting coefficient is determined according to the ratio of the first roughness to the second roughness, and the initial cutting depth is determined according to the second cutting length and the third cutting coefficient.

[0098] In implementation, the initial cutting depth is determined according to the product of the second cutting length and the third cutting coefficient.

[0099] Step S28, according to the initial cutting depth and the diameter of the crystal bar, the third cutting speed is determined according to the comparison result and the standard cutting speed.

[0100] In the implementation, the third intermediate value is determined according to the ratio of the initial cutting depth to 0.5 times of the diameter of the crystal bar, and the third cutting speed is determined according to the ratio of the standard cutting speed to the third intermediate value.

[0101] The first cutting parameter is determined by the diameter of the crystal bar, and the second cutting parameter is determined by the surface roughness of the silicon carbide crystal bar and the diameter of the crystal bar, so that the cutting quality and production efficiency of each silicon carbide crystal bar can be improved.

[0102] Please continue to refer to Figure 4 Specifically, in the step S2, if the first roughness and the second roughness are greater than or equal to the preset roughness threshold, it is determined that the third condition is met, and the third cutting method is used.

[0103] Specifically, the third cutting method includes:

[0104] In the cutting process, the cutting equipment takes the third cutting point as the initial cutting point, and cuts at a standard cutting speed, so as to complete the cutting process of the silicon carbide crystal bar; wherein, any point on the circular arc with a preset cutting length from the edge of the second surface on the first surface is the third cutting point.

[0105] The first roughness and the second roughness are relatively large, which can increase the friction in the cutting process. By taking the third cutting point as the initial cutting point and cutting at a standard cutting speed, the cutting quality of the silicon carbide crystal bar can be improved.

[0106] Step S3, according to the initial cutting method, the silicon carbide crystal bar is cut to obtain a silicon carbide wafer;

[0107] Step S4, according to the cutting texture direction and the bending degree of the surface of the silicon carbide wafer to determine the grinding parameters; the grinding parameters include grinding granularity and grinding pressure;

[0108] Specifically, in the step S4, the grinding parameters are determined according to the cutting texture direction and the bending degree of the surface of the silicon carbide wafer, including:

[0109] The cutting texture direction is compared with the preset cutting texture direction to determine whether the cutting texture direction meets the preset cutting texture direction;

[0110] If the cutting texture direction meets the preset cutting texture direction, the grinding granularity is set to a standard grinding granularity, and the grinding pressure is set to a standard grinding pressure.

[0111] if the cutting texture direction does not conform to the preset cutting texture direction, determining a grinding parameter according to the curvature.

[0112] It can be understood that any method and device capable of detecting the cutting texture direction of the cutting surface of the silicon carbide wafer in the prior art, such as an optical profiler, a texture analysis method based on computer vision, etc., falls within the protection scope of the present application, and will not be described here.

[0113] In implementation, the cutting texture direction is set as an angle range corresponding to a maximum number of cutting scratch tracks on the surface of the cutting surface of the silicon carbide wafer within a unit angle range centered on the initial cutting point, and the preset cutting texture direction is defined as an angle range corresponding to a preset number of cutting scratch tracks on the surface of the cutting surface of the silicon carbide wafer within the unit angle range centered on the initial cutting point. The cutting texture direction conforms to the preset cutting texture direction is defined as that the maximum number of cutting scratch tracks on the surface of the cutting surface of the silicon carbide wafer within the unit angle range centered on the initial cutting point conforms to the preset number range, and the cutting texture direction does not conform to the preset cutting texture direction is defined as that the maximum number of cutting scratch tracks on the surface of the cutting surface of the silicon carbide wafer within the unit angle range centered on the initial cutting point exceeds the preset number range.

[0114] Specifically, the actual implementer can determine the standard grinding granularity based on the mean value of the grinding granularity of the silicon carbide substrate passing the qualification test in the historical data, and preferably, the value range of the standard grinding granularity can be set as 0.5 μm-150 μm; the actual implementer can determine the standard grinding pressure based on the mean value of the grinding pressure of the silicon carbide substrate passing the qualification test in the historical data, and preferably, the value range of the standard grinding pressure can be set as 1 psi-3 psi.

[0115] Specifically, the determining of the grinding parameter according to the curvature includes:

[0116] comparing the curvature with a standard curvature to determine a first comparison value, and determining the grinding granularity according to the ratio of the first comparison value to the standard grinding granularity, and determining the grinding pressure according to the ratio of the first comparison value to the standard grinding pressure.

[0117] In implementation, the first comparison value is determined according to the ratio of the curvature to the standard curvature, the grinding granularity is determined according to the ratio of the standard grinding granularity to the first comparison value, and the grinding pressure is determined according to the ratio of the standard grinding pressure to the first comparison value.

[0118] Step S5, grinding the silicon carbide wafer according to the grinding parameter, and polishing the ground silicon carbide wafer to obtain a silicon carbide substrate.

[0119] In the implementation, the actual implementer can set the standard bending degree based on the average value of the bending degree of the silicon carbide wafer that passes the qualification test in the historical data, and preferably, the standard bending degree is set to 10-20 μm.

[0120] It should be noted that any device and method capable of polishing the silicon carbide wafer in the prior art falls within the protection scope of the present application, and will not be described here.

[0121] The present application determines the initial cutting mode of the silicon carbide crystal bar according to the surface roughness of the silicon carbide crystal bar, which can reduce the influence of the surface roughness of the silicon carbide crystal bar on the cutting process, improve the production efficiency and the quality of the silicon carbide substrate. The cutting texture direction of the wafer surface will affect the material removal rate and the surface roughness in the grinding process, and the bending degree of the wafer can affect the pressure distribution in the grinding process, and then affect the flatness of the whole wafer. By determining the grinding parameters according to the cutting texture direction and the bending degree of the silicon carbide wafer surface, the quality of the silicon carbide substrate can be further improved.

[0122] So far, the technical solutions of the present application have been described in combination with the preferred embodiments shown in the drawings, but those skilled in the art can easily understand that the protection scope of the present application is obviously not limited to these specific embodiments. Those skilled in the art can make equivalent changes or replacements to the related technical features without departing from the principles of the present application, and the technical solutions after the changes or replacements will fall within the protection scope of the present application.

Claims

1. A method of producing a silicon carbide substrate, characterized by, The method comprises the following steps: Step S1, detecting the surface of the prepared silicon carbide crystal rod to obtain the surface roughness of the silicon carbide crystal rod and the diameter of the crystal rod; wherein the surface roughness comprises a first roughness corresponding to a first surface and a second roughness corresponding to a second surface; Step S2, determining the initial cutting mode of the silicon carbide crystal rod according to the surface roughness, which comprises a first cutting mode and a second cutting mode; wherein, under the first condition, the first cutting mode is used, and the first cutting parameter corresponding to the first cutting mode is determined according to the diameter of the crystal rod, the first cutting parameter comprising a first cutting point and a first cutting speed; under the second condition, the second cutting mode is used, and the second cutting parameter is determined according to the surface roughness and the diameter of the crystal rod, the second cutting parameter comprising a second cutting point, a second cutting speed, an initial cutting depth and a third cutting speed; Step S3, cutting the silicon carbide crystal rod according to the initial cutting mode to obtain a silicon carbide wafer; Step S4, determining the grinding parameters according to the cutting texture direction and the bending degree of the surface of the silicon carbide wafer; the grinding parameters comprising the grinding granularity and the grinding pressure; Step S5, grinding the silicon carbide wafer according to the grinding parameters, and polishing the ground silicon carbide wafer to obtain a silicon carbide substrate; In step S2, the initial cutting mode of the silicon carbide crystal rod is determined, comprising: if the first roughness and the second roughness are both less than a preset roughness threshold, and the difference between the first roughness and the second roughness is less than a first preset difference, it is determined that the first condition is met, and the first cutting mode is used; if the first roughness and the second roughness are both less than a preset roughness threshold, and the difference between the first roughness and the second roughness is greater than or equal to the first preset difference, it is determined that the second condition is met, and the second cutting mode is used; In step S2, during the cutting process, the cutting equipment uses the first cutting point as the initial cutting point, and cuts at a constant first cutting speed to complete the cutting process of the silicon carbide crystal rod; wherein the obtained silicon carbide wafer has a second surface as a bottom surface, and any point on a circular arc on the first surface with a first cutting length from the edge of the second surface is a first cutting point; The second cutting mode divides the silicon carbide crystal rod into a first cutting part and a second cutting part; wherein, in the cutting process of the first cutting part, the cutting equipment uses the second cutting point as the initial cutting point, and the cutting depth is the initial cutting depth, and the cutting equipment starts to rotate at a constant second cutting speed to complete the cutting process of the first cutting part, wherein any point on a circular arc on the first surface with a second cutting length from the edge of the second surface is a second cutting point; in the cutting process of the second cutting part, the cutting equipment cuts at a constant third cutting speed to complete the cutting process of the second cutting part; In the cutting process, the cutting equipment sequentially completes the cutting of the first cutting part and the second cutting part to complete the cutting process of the silicon carbide crystal rod; The first cutting parameter is determined by the following steps: Step S21, determining a first cutting coefficient according to a square of a ratio of a difference between the diameter of the crystal bar and a preset diameter threshold and the preset diameter threshold; Step S22, determining a first cutting length according to a product of the diameter of the crystal bar and the first cutting coefficient; Step S23, determining a first intermediate value according to a ratio of the first cutting length and a preset cutting length, and determining a first cutting speed according to a product of the first intermediate value and a standard cutting speed; The second cutting parameter is determined by the following steps: Step S24, determining a second cutting coefficient according to a square of a ratio of a difference between the first roughness and the second roughness and the second roughness; Step S25, determining a second cutting length according to a product of the diameter of the crystal bar and the second cutting coefficient; Step S26, determining a second intermediate value according to a ratio of the second cutting length and a preset cutting length, and determining a second cutting speed according to a product of the second intermediate value and a standard cutting speed; Step S27, determining a third cutting coefficient according to a ratio of the first roughness and the second roughness, and determining an initial cutting depth according to a product of the second cutting length and the third cutting coefficient; Step S28, determining a third intermediate value according to a ratio of the initial cutting depth and 0.5 times of the diameter of the crystal bar, and determining a third cutting speed according to a ratio of the standard cutting speed and the third intermediate value.

2. The method of producing a silicon carbide substrate according to claim 1, wherein In the step S4, the grinding parameters are determined according to the cutting texture direction of the surface of the silicon carbide wafer and the curvature, including: Comparing the cutting texture direction with a preset cutting texture direction to determine whether the cutting texture direction conforms to the preset cutting texture direction; If the cutting texture direction conforms to the preset cutting texture direction, the grinding granularity is set as a standard grinding granularity, and the grinding pressure is set as a standard grinding pressure; If the cutting texture direction does not conform to the preset cutting texture direction, the grinding parameters are determined according to the curvature.

3. The method of producing a silicon carbide substrate according to claim 2, wherein The determination of the grinding parameters according to the curvature includes: Comparing the curvature with a standard curvature to determine a first comparison value, and determining the grinding granularity according to the first comparison value and a standard grinding granularity, and determining the grinding pressure according to the first comparison value and a standard grinding pressure.

4. The method of producing a silicon carbide substrate according to claim 3, wherein In the step S2, if the first roughness and the second roughness are both greater than or equal to a preset roughness threshold, it is determined that the third condition is met, and a third cutting mode is used.

5. The method of producing a silicon carbide substrate according to claim 4, wherein The third cutting mode includes: In the cutting process, the cutting equipment takes a third cutting point as an initial cutting point, and cuts at a standard cutting speed to complete the cutting process of the silicon carbide crystal bar; wherein, any point on a circular arc with a preset cutting length on the first surface and away from the edge of the second surface is the third cutting point.

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