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CN-121973026-A - Silicon carbide wafer thinning method

CN121973026ACN 121973026 ACN121973026 ACN 121973026ACN-121973026-A

Abstract

A method for thinning a silicon carbide wafer comprises the steps of carrying out rough grinding treatment on the wafer to be treated, carrying out fine grinding treatment on the wafer to be treated, wherein the average spindle feed rate of the fine grinding treatment stage is not greater than the average spindle feed rate of the rough grinding treatment stage, at least 1 treatment stage of the rough grinding treatment stage and the fine grinding treatment stage comprises at least 2 sub-stages, the spindle rotation speed of the latter sub-stage is greater than that of the former sub-stage, and the rough grinding treatment stage and the fine grinding treatment stage are suitable for introducing cooling liquid to reduce the temperature of the contact area of the wafer to be treated and a grinding wheel. The method accurately controls the force and heat in the grinding process, effectively improves the flatness of the wafer, reduces the damage to the surface of the wafer, reduces the residual stress, inhibits the warpage of the wafer, adapts to the processing requirements of each stage of wafer thinning, improves the processing quality of the wafer while ensuring the material removal rate, reduces the abrasion loss, prolongs the service life of the abrasion wheel, reduces the rejection of the wafer caused by warpage and cracks, improves the processing yield of the wafer, and saves the manufacturing cost.

Inventors

  • WANG DONG
  • ZHANG JINGRU
  • ZHANG WEN
  • Luo ben
  • SUN JIANJIAN
  • LOU YANFANG
  • LIU CHUNJUN
  • PENG TONGHUA
  • YANG JIAN

Assignees

  • 北京天科合达半导体股份有限公司
  • 江苏天科合达半导体有限公司

Dates

Publication Date
20260505
Application Date
20260326

Claims (19)

  1. 1. A method of thinning a silicon carbide wafer, comprising: providing a wafer to be processed; carrying out rough grinding treatment on the wafer to be treated; After the wafer to be processed is subjected to rough grinding treatment, the wafer to be processed is subjected to fine grinding treatment, and the average spindle feed rate of the fine grinding treatment stage is not greater than the average spindle feed rate of the rough grinding treatment stage; At least 1 of the coarse and fine grinding treatment stages comprises at least 2 sub-stages, of which the spindle speed in the latter sub-stage is greater than the spindle speed in the former sub-stage; the rough grinding treatment stage and the fine grinding treatment stage are adapted to be supplied with a cooling liquid to reduce the temperature of the contact area of the wafer to be treated with the grinding wheel.
  2. 2. A silicon carbide wafer thinning method according to claim 1, wherein the removal amount of the rough grinding process stage is greater than the removal amount of the fine grinding process stage.
  3. 3. A silicon carbide wafer thinning method according to claim 1 or 2 wherein the removal of the rough grinding stage is greater than 85% of the total removal.
  4. 4. The method of thinning a silicon carbide wafer according to claim 1, wherein the rough grinding process stage comprises at least 2 sub-stages; In the at least 2 sub-stages, the spindle speed in the latter sub-stage is greater than the spindle speed in the former sub-stage.
  5. 5. The method of claim 4, wherein the removal of the first sub-stage of the at least 2 sub-stages is 20% -80% of the total removal of the rough grinding stage.
  6. 6. The method of thinning a silicon carbide wafer according to claim 4, wherein the removal amount in the latter sub-stage is smaller than the removal amount in the former sub-stage among the at least 2 sub-stages.
  7. 7. The method of thinning a silicon carbide wafer according to claim 4, wherein the table rotational speed of each of the at least 2 sub-stages is positively correlated with the spindle rotational speed.
  8. 8. The method of thinning a silicon carbide wafer according to claim 7, wherein the stage rotation speed in the latter sub-stage is not less than the stage rotation speed in the former sub-stage among the at least 2 sub-stages.
  9. 9. The method of thinning a silicon carbide wafer according to claim 4, wherein the coolant flow rate in each of the at least 2 sub-stages is positively correlated with the corresponding spindle feed rate.
  10. 10. The method of thinning a silicon carbide wafer according to claim 9, wherein the coolant flow rate in the latter sub-stage is not greater than the coolant flow rate in the former sub-stage among the at least 2 sub-stages.
  11. 11. The method of thinning a silicon carbide wafer according to claim 4, wherein a first sub-stage of the at least 2 sub-stages includes contacting and stabilizing for two periods of time, the spindle feed rate of the contacting period of time being less than the spindle feed rate of the stabilizing period of time.
  12. 12. A silicon carbide wafer thinning method according to claim 1, wherein the finish grinding stage comprises at least 2 stages; In the at least 2 sub-stages, the spindle speed in the latter sub-stage is greater than the spindle speed in the former sub-stage.
  13. 13. The method of thinning a silicon carbide wafer according to claim 12, wherein the removal amount in the first sub-stage of the at least 2 sub-stages is 20% to 80% of the total removal amount in the finish grinding process stage.
  14. 14. The method of thinning a silicon carbide wafer according to claim 12, wherein the removal amount in the latter sub-stage is smaller than the removal amount in the former sub-stage among the at least 2 sub-stages.
  15. 15. The method of claim 12, wherein the table rotation speed of each of the at least 2 sub-stages is positively correlated with the spindle rotation speed.
  16. 16. The method of thinning a silicon carbide wafer according to claim 15, wherein the stage rotation speed in the latter sub-stage is not less than the stage rotation speed in the former sub-stage among the at least 2 sub-stages.
  17. 17. The method of claim 12, wherein the coolant flow rate in each of the at least 2 sub-stages is positively correlated with the corresponding spindle feed rate.
  18. 18. The method of thinning a silicon carbide wafer according to claim 17, wherein the coolant flow rate in the latter sub-stage is not greater than the coolant flow rate in the former sub-stage among the at least 2 sub-stages.
  19. 19. The method of thinning a silicon carbide wafer according to claim 1, wherein the wafer to be processed comprises a substrate and a laser modified layer on the substrate.

Description

Silicon carbide wafer thinning method Technical Field The invention relates to the field of semiconductor processing and manufacturing, in particular to a silicon carbide wafer thinning method. Background Silicon carbide (SiC) is a wide bandgap semiconductor material formed from silicon (Si) and carbon (C) joined by covalent bonds, the unique properties of which make it an ideal choice for high temperature, high frequency, high voltage applications. It has extreme physical properties including ultra-high hardness, excellent thermal management capability, low coefficient of thermal expansion. Meanwhile, the electron saturation drift velocity is higher and the forbidden bandwidth is wider (3.2 eV). The high-frequency isolation module is mainly applied to a main drive inverter, an OBC (on-board diagnostics) and the like of a new energy automobile, a high-frequency isolation module of a photovoltaic inverter, a radio-frequency power amplifier in 5G communication, a high-temperature-resistant sensor required by aerospace and the like. In the silicon carbide processing process, the thinning procedure is to completely remove a laser peeling damage layer on the surface of a silicon carbide wafer, the laser peeling damage layer has larger surface roughness, the silicon carbide particles are sharp, and the requirements on a rough grinding thinning grinding wheel and a thinning process are higher. After coarse grinding and polishing to a certain extent, the surface roughness of the wafer can be processed to nano-scale by matching with a grinding wheel with fine grinding and high mesh number, and the wafer has ideal surface shape. The silicon carbide material has high hardness and high brittleness, and is extremely easy to introduce surface, subsurface damage, microcrack and residual stress in the grinding thinning process, so that wafers are warped and broken. However, current methods of silicon carbide wafer thinning remain to be improved. Disclosure of Invention The invention solves the problem of how to accurately match the surface state, stress change and heat accumulation of each stage of wafer thinning in the process of thinning the silicon carbide wafer, reduce the deviation of the total thickness of the wafer and improve the flatness of the surface of the wafer. In order to solve the problems, the invention provides a silicon carbide wafer thinning method, which comprises the steps of providing a wafer to be processed, carrying out rough grinding treatment on the wafer to be processed, carrying out fine grinding treatment on the wafer to be processed after the wafer to be processed is subjected to rough grinding treatment, wherein the average spindle feed rate of the fine grinding treatment stage is not greater than the average spindle feed rate of the rough grinding treatment stage, at least 1 treatment stage of the rough grinding treatment stage and the fine grinding treatment stage comprises at least 2 sub-stages, the spindle rotation speed of the latter sub-stage is greater than the spindle rotation speed of the former sub-stage in the at least 2 sub-stages, and the rough grinding treatment stage and the fine grinding treatment stage are suitable for introducing cooling liquid to reduce the temperature of a contact area of the wafer to be processed and a grinding wheel. Optionally, the removal of the coarse grinding stage is greater than the removal of the fine grinding stage. Optionally, the removal of the coarse grinding stage is greater than 85% of the total removal. Optionally, the rough grinding treatment stage comprises at least 2 sub-stages, and the spindle rotation speed in the latter sub-stage is larger than that in the former sub-stage in the at least 2 sub-stages. Optionally, the removal amount of the first sub-stage is 20% -80% of the total removal amount of the rough grinding treatment stage in the at least 2 sub-stages. Optionally, the removal amount in the latter sub-stage is smaller than the removal amount in the former sub-stage in the at least 2 sub-stages. Optionally, in the at least 2 sub-stages, the rotation speed of the workbench in each sub-stage is positively correlated with the rotation speed of the main shaft. Optionally, in the at least 2 sub-stages, the rotation speed of the workbench in the later sub-stage is not less than the rotation speed of the workbench in the former sub-stage. Optionally, among the at least 2 sub-stages, the coolant flow rate of each sub-stage is positively correlated with the corresponding spindle feed rate. Optionally, in the at least 2 sub-stages, the coolant flow rate in the latter sub-stage is not greater than the coolant flow rate in the former sub-stage. Optionally, of the at least 2 sub-phases, the first sub-phase includes contacting and stabilizing for two periods of time, the spindle feed rate of the contacting period of time being less than the spindle feed rate of the stabilizing period of time. Optionally, the fine grinding treatment stage co