A silicon carbide grinding process

Abstract

The application discloses a silicon carbide grinding process and belongs to the field of silicon carbide. The silicon carbide grinding process comprises the following steps: S1, parameter setting, detecting the shape and size of a silicon carbide base body and setting parameters of a grinding action according to the shape and size; S2, first grinding, performing rough grinding treatment on the silicon carbide base body according to the parameters set in step one; S3, second grinding, performing fine grinding treatment on the silicon carbide base body according to the parameters set in step one, and obtaining a silicon carbide wafer finished product; and S4, cleaning, cleaning and spin-drying the silicon carbide wafer finished product after the second grinding, and outputting the cleaned silicon carbide wafer finished product. The silicon carbide wafer finished product can be simultaneously improved in grinding efficiency and grinding precision by setting parameters for rough grinding and fine grinding of the silicon carbide base body according to the shape and size of the silicon carbide base body.

Description

Technical Field

[0001] This invention relates to the field of silicon carbide, and more specifically, to a silicon carbide grinding process. Background Technology

[0002] The thinning process used in silicon carbide substrate processing is basically the same as that used in first-generation semiconductor silicon wafers. Both use planetary plates, cast iron grinding discs, and diamond grinding fluid for double-sided grinding and thinning.

[0003] This approach has the following problems:

[0004] Because silicon carbide wafers have very different properties from silicon wafers, especially in terms of Mohs hardness, silicon wafers have a Mohs hardness of around 6.5, while silicon carbide wafers have a Mohs hardness of 9.5. This results in a long grinding and thinning time for silicon carbide wafers, a very low material removal rate (MRR), significantly low efficiency, and increased production and operating costs.

[0005] 2. The surface quality parameters of silicon carbide wafers after grinding are relatively low, the surface mechanical stress damage is large, the stress damage layer is relatively deep, and the surface machining accuracy is not high. Although TTV is possible, the processing thickness is not easy to control, the thickness of different batches of wafers varies greatly, and the workload of subsequent processes is large.

[0006] In summary, existing silicon carbide grinding processes cannot simultaneously achieve good grinding efficiency and grinding precision. Summary of the Invention

[0007] 1. Technical problems to be solved

[0008] In view of the problems existing in the prior art, the purpose of this invention is to provide a silicon carbide grinding process that can set the parameters for coarse grinding and fine grinding of the silicon carbide substrate according to the shape and size of the silicon carbide substrate, thereby simultaneously improving the grinding efficiency and grinding accuracy of the finished silicon carbide wafer.

[0009] 2. Technical Solution

[0010] To solve the above problems, the present invention adopts the following technical solution.

[0011] A silicon carbide grinding process includes the following steps:

[0012] S1: Parameter settings, detect the shape and size of the silicon carbide substrate, and set the parameters of the grinding action according to its shape and size;

[0013] S2: First grinding: The silicon carbide substrate is coarsely ground according to the parameters set in step one;

[0014] S3: Secondary polishing. The silicon carbide substrate is finely polished according to the parameters set in step one to obtain the finished silicon carbide wafer.

[0015] Furthermore, the polishing action includes coarse polishing and fine polishing, and the polishing parameters include polishing speed and polishing thickness.

[0016] Furthermore, the parameter settings include the following steps:

[0017] S101: Data scanning detection, scanning the surface of the silicon carbide substrate to determine the dimensional data of the silicon carbide substrate;

[0018] S102: Rough grinding thickness setting. The rough grinding thickness is calculated based on the size data of the data scan to obtain the rough grinding thickness.

[0019] S103: Fine grinding thickness setting, the fine grinding thickness is calculated based on the rough grinding thickness.

[0020] Furthermore, the calculation process for the grinding thickness in rough grinding is as follows;

[0021] S10201: Take the scanning value of the highest point of the protrusion on the silicon carbide substrate by the scanning equipment as the initial polishing height;

[0022] S10202: The scanning value of the lowest point of the silicon carbide substrate recess by the scanning equipment is taken as the end polishing height;

[0023] S10203: Calculate the minimum rough grinding thickness by subtracting the initial grinding height from the final grinding height;

[0024] S10204: The rough grinding thickness is the value of the grinding height that is not less than the minimum rough grinding thickness.

[0025] Furthermore, the calculation process for the grinding thickness includes the following steps:

[0026] S10301: Calculate the depth of the damaged layer during the rough grinding process of the silicon carbide substrate based on the grinding parameters of the rough grinding.

[0027] S10302: Determine the minimum grinding thickness for fine grinding that is greater than the depth of the damaged layer after rough grinding of the silicon carbide substrate.

[0028] S10303: Calculate the fine grinding thickness based on the thickness of the finished silicon carbide wafer and the minimum grinding thickness after grinding the silicon carbide substrate.

[0029] Furthermore, the specific calculation process for the fine grinding thickness includes the following steps:

[0030] Let the two end faces of the silicon carbide substrate be end face a and end face b, respectively;

[0031] The rough grinding thickness and minimum grinding thickness of end face a are calculated sequentially based on the initial grinding height and the final grinding height of end face a. The rough grinding thickness and minimum grinding thickness of end face b are calculated based on the initial grinding height and the final grinding height of end face b.

[0032] The output value is obtained by subtracting the rough grinding thickness of end face a, the rough grinding thickness of end face b, and the thickness of the finished silicon carbide product from the thickness of the silicon carbide substrate.

[0033] Take half of the output value as the fine grinding budget value, and compare the fine grinding budget value with the minimum grinding thickness;

[0034] If the fine grinding budget value is not less than the minimum grinding thickness, the fine grinding budget value is the final fine grinding thickness.

[0035] If the fine grinding budget value is less than the minimum grinding thickness, then reduce the coarse grinding thickness value and recalculate;

[0036] Once the rough grinding thickness is less than the minimum rough grinding thickness, no further calculations are performed, and the silicon carbide substrate is judged to be a defective product.

[0037] Furthermore, step S2 includes the following steps:

[0038] S201: Select the grinding wheel model for rough grinding based on the silicon carbide substrate size data obtained from scanning in S101;

[0039] S202: Grind the silicon carbide substrate to the coarse grinding thickness set in S102 according to the set coarse grinding speed.

[0040] Furthermore, step S3 includes the following steps:

[0041] S301: Select the grinding wheel model for rough grinding based on the silicon carbide substrate size data obtained from scanning in S101;

[0042] S302: Grind the silicon carbide substrate to the fine grinding thickness set in S103 according to the set coarse grinding speed to obtain the finished silicon carbide wafer.

[0043] Furthermore, the process may also include the following steps:

[0044] S4: Cleaning. The silicon carbide wafers after secondary polishing are cleaned and dried. After cleaning and drying, the cleaned silicon carbide wafers are output.

[0045] 3. Beneficial effects

[0046] Compared with the prior art, the advantages of this invention are:

[0047] (1) This solution can set the parameters for coarse grinding and fine grinding of silicon carbide substrate according to the shape and size of silicon carbide substrate through S1-S4. During coarse grinding, a large speed is maintained and the maximum coarse grinding thickness is set to improve work efficiency. Then, the stress damage caused by coarse grinding is eliminated through fine grinding, and the precision of silicon carbide wafer is guaranteed. Thus, the grinding efficiency and grinding precision of silicon carbide wafer are improved simultaneously. Attached Figure Description

[0048] Figure 1 This is a flowchart of the steps of the present invention. Detailed Implementation

[0049] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0050] Example:

[0051] Please see Figure 1 A silicon carbide grinding process includes the following steps:

[0052] Step 1: Parameter setting. Detect the shape and size of the silicon carbide substrate, and set the parameters of the grinding action according to its shape and size;

[0053] Specifically, the polishing action includes coarse polishing and fine polishing. The polishing parameters include polishing speed and polishing thickness, and the polishing speed and polishing thickness are directly proportional. The coarse polishing has a faster polishing speed and a thicker polishing thickness, while the fine polishing has a slower polishing speed and a thinner polishing thickness.

[0054] Furthermore, to more clearly explain the parameter settings, this technical solution discloses the specific structure of the parameter settings, which specifically includes the following steps:

[0055] A1. Data scanning and inspection: The surface of the silicon carbide substrate is scanned using a scanning device to determine the dimensional data of the unevenness of the silicon carbide substrate;

[0056] A2. Rough grinding thickness setting: The rough grinding thickness is calculated based on the size data of the data scan.

[0057] The calculation process for the grinding thickness in rough grinding is as follows;

[0058] A201. Take the scanning value (i.e. the value with the shortest scanning distance) of the scanning equipment scanning the highest point of the silicon carbide substrate protrusion as the initial polishing height H1;

[0059] A202. Take the scanning value (i.e. the value of the maximum scanning distance) of the scanning equipment scanning the lowest point of the silicon carbide substrate depression as the end polishing height H2;

[0060] A203. Calculate the minimum rough grinding thickness H3 by subtracting the initial grinding height H1 from the final grinding height H2;

[0061] A204. The rough grinding thickness H4 is a value that is not less than the minimum rough grinding thickness H3, and it is preferably the maximum value, that is, H2-H1=H3≦H4.

[0062] A3. Fine grinding thickness setting: The fine grinding thickness is calculated based on the coarse grinding thickness.

[0063] Here, since the coarse grinding process will damage the silicon carbide substrate, resulting in a damage layer of a certain depth and residual stress during grinding on the surface of the silicon carbide substrate, the damage layer generated during the coarse grinding process should be completely removed by fine grinding.

[0064] Specifically, the process of calculating the grinding thickness includes the following steps:

[0065] A301. Calculate the depth of the damaged layer H5 during the rough grinding of the silicon carbide substrate based on the grinding parameters;

[0066] A302. The minimum grinding thickness H6 for fine grinding is determined based on the damage layer depth H5 after coarse grinding of the silicon carbide substrate, wherein the minimum grinding thickness H6 is greater than the damage layer depth H5.

[0067] A303. Calculate the fine grinding thickness H7 based on the thickness of the finished silicon carbide wafer after grinding the silicon carbide substrate and the minimum grinding thickness H6.

[0068] The specific calculation process includes the following steps:

[0069] Let the thickness of the silicon carbide substrate be Hn, the thickness of the finished silicon carbide product be Hx, and the two end faces of the silicon carbide substrate be end face a and end face b, respectively. The initial grinding height and the final grinding height of end face a are H1a and H2a, respectively, and the initial grinding height and the final grinding height of end face b are H1b and H2b, respectively.

[0070] Based on the initial grinding height H1a and the final grinding height H2a of end face a, the rough grinding thickness H4a and the minimum grinding thickness H6a of end face a are calculated sequentially. Based on the initial grinding height H1b and the final grinding height H2b of end face b, the rough grinding thickness H4b and the minimum grinding thickness H6b of end face b are calculated.

[0071] The output value Ho is obtained by subtracting the rough grinding thickness H4a of end face a, the rough grinding thickness H4b of end face b, and the thickness Hx of the finished silicon carbide product from the thickness Hn of the silicon carbide substrate.

[0072] Half of the output value Ho is taken as the fine grinding budget value Hl, and the fine grinding budget value Hl is compared with the minimum grinding thickness H6b;

[0073] If the fine grinding budget value Hl is not less than the minimum grinding thickness H6b, the fine grinding budget value Hl is the final fine grinding thickness H7.

[0074] If the fine grinding budget value Hl is less than the minimum grinding thickness H6b, then reduce the coarse grinding thickness H4 and recalculate until the coarse grinding thickness H4 is less than the minimum coarse grinding thickness H3. Then stop the calculation and determine that the silicon carbide substrate is a defective product.

[0075] Step 2: First grinding. The silicon carbide substrate is coarsely ground according to the parameters set in Step 1.

[0076] Specifically, step two includes the following steps:

[0077] B1. Select the grinding wheel model for rough grinding based on the silicon carbide substrate size data obtained from scanning in A1;

[0078] B2. Grind the silicon carbide substrate to the coarse grinding thickness set in A2 according to the set coarse grinding speed;

[0079] Step 3: Secondary polishing. The silicon carbide substrate is finely polished according to the parameters set in Step 1 to obtain the finished silicon carbide wafer.

[0080] Specifically, step three includes the following steps:

[0081] C1. Select the grinding wheel model for rough grinding based on the silicon carbide substrate size data obtained from scanning in A1;

[0082] C2. Grind the silicon carbide substrate to the fine grinding thickness set in A3 according to the set coarse grinding speed to obtain the finished silicon carbide wafer;

[0083] Based on the above, the process may further include the following steps:

[0084] Step 4: Cleaning. The silicon carbide wafers after secondary polishing are cleaned and dried. After cleaning and drying, the cleaned silicon carbide wafers are output.

[0085] In summary, this technical solution, through the above steps, can set the parameters for coarse and fine grinding of the silicon carbide substrate according to its shape and size. During coarse grinding, a higher speed is maintained and the maximum coarse grinding thickness is set to improve work efficiency. Then, fine grinding eliminates the stress damage caused by coarse grinding and ensures the precision of the finished silicon carbide wafer. Thus, the grinding efficiency and grinding precision of the finished silicon carbide wafer can be improved simultaneously.

[0086] The above description is merely a preferred embodiment of the present invention; however, the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and its improved concepts, should be covered within the scope of protection of the present invention.

Claims

1. A silicon carbide grinding process, characterized in that: It includes the following steps: S1: Parameter settings, detect the shape and size of the silicon carbide substrate, and set the parameters of the grinding action according to its shape and size; S2: First grinding: The silicon carbide substrate is coarsely ground according to the parameters set in step one; S3: Secondary polishing: The silicon carbide substrate is finely polished according to the parameters set in step one to obtain the finished silicon carbide wafer. The parameter settings include the following steps: S101: Data scanning detection, scanning the surface of the silicon carbide substrate to determine the dimensional data of the silicon carbide substrate; S102: Rough grinding thickness setting. The rough grinding thickness is calculated based on the size data of the data scan to obtain the rough grinding thickness. S103: Fine grinding thickness setting, the fine grinding thickness is calculated based on the coarse grinding thickness; The calculation process for the grinding thickness in rough grinding is as follows; S10201: Take the scanning value of the highest point of the protrusion on the silicon carbide substrate by the scanning equipment as the initial polishing height; S10202: The scanning value of the lowest point of the silicon carbide substrate recess by the scanning equipment is taken as the end polishing height; S10203: Calculate the minimum rough grinding thickness by subtracting the initial grinding height from the final grinding height; S10204: The rough grinding thickness is the value of the grinding height that is not less than the minimum rough grinding thickness. The process of calculating the grinding thickness during fine grinding includes the following steps: S10301: Calculate the depth of the damaged layer during the rough grinding process of the silicon carbide substrate based on the grinding parameters of the rough grinding. S10302: Determine the minimum grinding thickness for fine grinding that is greater than the depth of the damaged layer after rough grinding of the silicon carbide substrate. S10303: Calculate the fine grinding thickness based on the thickness of the finished silicon carbide wafer and the minimum grinding thickness after grinding the silicon carbide substrate. The specific calculation process for the fine grinding thickness includes the following steps: Let the two end faces of the silicon carbide substrate be end face a and end face b, respectively; The rough grinding thickness and minimum grinding thickness of end face a are calculated sequentially based on the initial grinding height and the final grinding height of end face a. The rough grinding thickness and minimum grinding thickness of end face b are calculated based on the initial grinding height and the final grinding height of end face b. The output value is obtained by subtracting the rough grinding thickness of end face a, the rough grinding thickness of end face b, and the thickness of the finished silicon carbide product from the thickness of the silicon carbide substrate. Take half of the output value as the fine grinding budget value, and compare the fine grinding budget value with the minimum grinding thickness; If the fine grinding budget value is not less than the minimum grinding thickness, the fine grinding budget value is the final fine grinding thickness. If the fine grinding budget value is less than the minimum grinding thickness, then reduce the coarse grinding thickness value and recalculate; Once the rough grinding thickness is less than the minimum rough grinding thickness, no further calculations are performed, and the silicon carbide substrate is judged to be a defective product.

2. The silicon carbide grinding process according to claim 1, characterized in that: The polishing action includes coarse polishing and fine polishing, and the polishing parameters include polishing speed and polishing thickness.

3. The silicon carbide grinding process according to claim 1, characterized in that: S2 includes the following steps: S201: Select the grinding wheel model for rough grinding based on the silicon carbide substrate size data obtained from scanning in S101; S202: Grind the silicon carbide substrate to the coarse grinding thickness set in S102 according to the set coarse grinding speed.

4. The silicon carbide grinding process according to claim 1, characterized in that: S3 includes the following steps: S301: Select the grinding wheel model for rough grinding based on the silicon carbide substrate size data obtained from scanning in S101; S302: Grind the silicon carbide substrate to the fine grinding thickness set in S103 according to the set coarse grinding speed to obtain the finished silicon carbide wafer.

5. The silicon carbide grinding process according to claim 1, characterized in that: The process also includes the following steps: S4: Cleaning. The silicon carbide wafers after secondary polishing are cleaned and dried. After cleaning and drying, the cleaned silicon carbide wafers are output.

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