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CN-122028717-A - Method for reducing machining stress of large-size silicon carbide wafer

CN122028717ACN 122028717 ACN122028717 ACN 122028717ACN-122028717-A

Abstract

The application discloses a method for reducing machining stress of a large-size silicon carbide wafer, which comprises the steps of carrying out surface activation on the machined silicon carbide wafer, forming an adhesion layer, carrying out low-temperature heat treatment and stripping the adhesion layer, wherein the formation of the adhesion layer comprises the step of sequentially forming an adhesion promoting layer and a stress buffering adhesion layer on the surface of the activated silicon carbide wafer. The adhesion layer prepared by the application can be removed by chemical, mechanical and other methods, the material is not processed and deformed in the processing process, the mechanical processing stress is not directly introduced, the operation method is simple, compared with the traditional processing route, the steps are simple, the processing period is short, the surface residual stress of a final sample is less than 10Mpa, the surface Ra is less than 0.2 nm, and the whole wafer warpage (Warp) is less than 20 mu m.

Inventors

  • Chao huan
  • Wang Shuoxue
  • ZHANG WENWEN
  • YANG WENCHENG
  • 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
20260512
Application Date
20260211

Claims (10)

  1. 1.A method of reducing machining stress in a large-size silicon carbide wafer, comprising: Carrying out surface activation, forming an adhesion layer, low-temperature heat treatment and stripping the adhesion layer on the mechanically processed silicon carbide wafer; the forming of the adhesion layer comprises the step of sequentially forming an adhesion promoting layer and a stress buffering adhesion layer on the surface of the activated silicon carbide wafer.
  2. 2. The method of claim 1, wherein the stress buffer attachment layer comprises a nickel layer; the stress buffering attachment layer has a thickness of 5 μm to 10 μm.
  3. 3. The method of claim 1, wherein forming the stress buffer adhesion layer comprises electroless plating nickel on a silicon carbide wafer having an adhesion promoting layer to form the stress buffer adhesion layer; The chemical nickel plating solution used in the chemical nickel plating comprises, by mass, 180 to 220 parts of nickel sulfate, 180 to 220 parts of sodium hypophosphite, 380 to 420 parts of sodium citrate, 380 to 420 parts of ammonium chloride, 0.02 to 0.04 part of potassium iodate and 9800 to 10200 parts of water; the pH value of the electroless nickel plating solution is 9-9.5; ammonia water is used for regulating the pH value in the chemical nickel plating solution; the electroless nickel plating temperature is 80 ℃ to 90 ℃.
  4. 4. The method of claim 1, wherein forming an adhesion promoting layer comprises magnetron sputter depositing an adhesion promoting layer; The adhesion promoting layer comprises a chromium layer; the adhesion promoting layer has a thickness of 8nm to 12nm.
  5. 5. The method of claim 1, wherein the release attachment layer comprises immersing in a nitric acid solution to release the attachment layer; The temperature of the release attachment layer is 30 ℃ to 40 ℃; The volume ratio of nitric acid to water in the nitric acid solution is 1 (3-10); the time for peeling off the adhesive layer is 5min to 30min.
  6. 6. The method of claim 1, wherein the low temperature heat treatment comprises inert gas comprising cooling to 300 ℃ to 600 ℃ and incubating; The cooling rate is 8-12 ℃ per minute; the heat preservation time is 1h to 5h.
  7. 7. The method of claim 1, wherein the removing the attachment layer further comprises finish polishing; the time of the finish polishing is 5min to 20min; the polishing liquid for the finish polishing is alkaline silicon dioxide polishing liquid and/or cerium dioxide polishing liquid.
  8. 8. The method of claim 1, wherein the surface activation comprises plasma RF treating the machined silicon carbide wafer and sensitizing in an activation solution; The sensitization time is 8min to 12min; the activating solution comprises, by mass, 1 to 3 parts of palladium chloride, 180 to 220 parts of stannous chloride, 2000 to 2400 parts of 37% hydrochloric acid, 1800 to 2200 parts of sodium chloride and 9800 to 10200 parts of water; The plasma RF treatment is performed under the protection of inert gas; the inert gas comprises argon; The power of the plasma RF treatment is 180W to 220W; the plasma RF treatment time is 8min to 12min.
  9. 9. The method of claim 8, wherein the mechanically processed silicon carbide wafer is subjected to ultrasonic cleaning in turn in deionized water, acetone and ethanol, and then subjected to surface activation; the deionized water is ultrasonically cleaned for 8 to 12 minutes; the time for ultrasonic cleaning of the acetone is 8-12 min; The ultrasonic cleaning time of the ethanol is 8min to 12min.
  10. 10. The method of claim 1, wherein the machined silicon carbide wafer has a diameter of 100mm to 300mm; The thickness of the machined silicon carbide wafer is 300 μm to 800 μm.

Description

Method for reducing machining stress of large-size silicon carbide wafer Technical Field The application relates to the technical field of silicon carbide wafer processing, in particular to a method for reducing machining stress of a large-size silicon carbide wafer. Background Silicon carbide (SiC) is used as a third-generation semiconductor material and high-performance structural ceramic, and has important application in the fields of power electronics, aerospace, nuclear energy, optical systems and the like. However, the high hardness, high brittleness of silicon carbide makes its mechanical processing (e.g., cutting, grinding, lapping) extremely difficult, with the inevitable creation of microcracks, dislocations, and residual tensile stresses of up to hundreds of megapascals at the surface and subsurface during processing. These defects and stresses can severely compromise the mechanical strength, fatigue life, and reliability of the wafer. The conventional stress relief methods at present are that high temperature annealing is liable to cause crystal quality change, dimensional deformation and surface oxidation, chemical etching (such as) Chemical Mechanical Polishing (CMP) can improve surface quality, but has limited elimination and low efficiency of deep stress caused by the previous process. Therefore, developing a method that can reduce the machining stress of large-sized silicon carbide wafers is a problem that needs to be solved by those skilled in the art. Disclosure of Invention In view of the above, the application provides a method which has controllable process and obvious effect, can synchronously remove a processing damage layer and greatly reduces residual stress. The application provides a method for reducing machining stress of a large-size silicon carbide wafer, which comprises the following steps: Carrying out surface activation, forming an adhesion layer, low-temperature heat treatment and stripping the adhesion layer on the mechanically processed silicon carbide wafer; the forming of the adhesion layer comprises the step of sequentially forming an adhesion promoting layer and a stress buffering adhesion layer on the surface of the activated silicon carbide wafer. In some specific implementations, the stress buffer attachment layer includes a nickel layer; the stress buffering attachment layer has a thickness of 5 μm to 10 μm. In some specific implementations, the forming the stress buffer adhesion layer includes electroless plating nickel on the silicon carbide wafer with the adhesion promoting layer to form the stress buffer adhesion layer; the chemical nickel plating solution used in the chemical nickel plating comprises, by mass, 180-220 parts of nickel sulfate, 180-220 parts of sodium hypophosphite, 380-420 parts of sodium citrate, 380-420 parts of ammonium chloride, 0.02-0.04 part of potassium iodate, 9800-10200 parts of water; the pH value of the electroless nickel plating solution is 9-9.5; ammonia water is used for regulating the pH value in the chemical nickel plating solution; the electroless nickel plating temperature is 80 ℃ to 90 ℃. In some specific implementations, the forming the adhesion promoting layer includes magnetron sputter depositing the adhesion promoting layer; The adhesion promoting layer comprises a chromium layer; the adhesion promoting layer has a thickness of 8nm to 12nm. In some specific implementations, the release attachment layer includes immersing in a nitric acid solution to release the attachment layer; The temperature of the release attachment layer is 30 ℃ to 40 ℃; The volume ratio of nitric acid to water in the nitric acid solution is 1 (3-10); the time for peeling off the adhesive layer is 5min to 30min. In some specific implementations, the low temperature heat treatment includes inert gas including cooling to 300 ℃ to 600 ℃ and maintaining the temperature; The cooling rate is 8-12 ℃ per minute; the heat preservation time is 1h to 5h. In some specific implementations, the removing the attachment layer further includes finish polishing; the time of the finish polishing is 5min to 20min; the polishing liquid for the finish polishing is alkaline silicon dioxide polishing liquid and/or cerium dioxide polishing liquid. In some specific implementations, the surface activation includes plasma RF treatment of the machined silicon carbide wafer and sensitization in an activation solution; The sensitization time is 8min to 12min; the activating solution comprises, by mass, 1 to 3 parts of palladium chloride, 180 to 220 parts of stannous chloride, 2000 to 2400 parts of 37% hydrochloric acid, 1800 to 2200 parts of sodium chloride and 9800 to 10200 parts of water; The plasma RF treatment is performed under the protection of inert gas; the inert gas comprises argon; The power of the plasma RF treatment is 180W to 220W; the plasma RF treatment time is 8min to 12min. In some specific implementations, the mechanically processed silicon carbide wafer is seq