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CN-121624971-B - Cutting method of silicon carbide crystal bar

CN121624971BCN 121624971 BCN121624971 BCN 121624971BCN-121624971-B

Abstract

The application discloses a cutting method of a silicon carbide crystal bar, which comprises the steps of providing a crystal bar to be cut, determining a cutter-in top point of the crystal bar in the cutting direction, adhering a sacrificial component at the cutter-in top point, covering the cutter-in top point by the sacrificial component and extending along the axial direction of the crystal bar, forming a rigid adhesive layer by adhesive, controlling a cutting wire net to feed in the direction perpendicular to the axial direction of the crystal bar, enabling the cutting wire net to cut into the sacrificial component first and then cut into the crystal bar, wherein the material of the sacrificial component is the same as that of the crystal bar, or the absolute value of the deviation between the Vickers hardness of the sacrificial component and the Vickers hardness of the crystal bar is smaller than a preset threshold value, so that the continuity of cutting stress is maintained when the cutting wire net cuts into the crystal bar from the sacrificial component, cutter-in line marks caused by axial movement of a cutting line are avoided, the deformation quantity of a wafer at the cutter-in position is reduced, the warp degree and the bending degree of the wafer are effectively reduced, the probability of extra repair is reduced, and the problem of direct scrapping of the wafer caused by the lines of the line mark is solved.

Inventors

  • WANG TAO
  • HAO HAN
  • ZHAO XINTIAN

Assignees

  • 宁波阿尔法半导体有限公司

Dates

Publication Date
20260512
Application Date
20260205

Claims (7)

  1. 1. A method of cutting a silicon carbide ingot, comprising: s100, providing a crystal bar to be cut, wherein the crystal bar is provided with an arc-shaped peripheral surface extending along the axial direction; S200, determining a cutter entering peak of the crystal bar in the cutting direction, and bonding a sacrificial component at the cutter entering peak, wherein the sacrificial component covers the cutter entering peak and extends along the axial direction of the crystal bar, and the adhesive forms a rigid adhesive layer; S300, controlling a cutting wire net to feed along the direction perpendicular to the axial direction of the crystal bar, so that the cutting wire net firstly cuts into the sacrificial component and then cuts into the crystal bar, wherein the material of the sacrificial component is the same as that of the crystal bar, or the absolute value of the deviation between the Vickers hardness of the sacrificial component and that of the crystal bar is smaller than a preset threshold value, so that the continuity of cutting stress is maintained when the cutting wire net cuts into the crystal bar from the sacrificial component; In step S300, the preset threshold is 200HV; the thickness of the adhesive layer is controlled between 2 mu m and 10 mu m, and the Shore hardness D of the adhesive layer is more than 80.
  2. 2. The method of cutting according to claim 1, wherein the thickness H of the sacrificial member in the cutting direction is 3 mm≤H≤10 mm.
  3. 3. The cutting method according to any one of claims 1 to 2, wherein the sacrificial member comprises a plurality of sacrificial blocks disposed along a circumferential direction of the ingot, wherein the sacrificial blocks located in the middle cover the cutting-in vertices, and the sacrificial blocks located on both sides are disposed obliquely with respect to the sacrificial blocks located in the middle so that bottom surfaces of the plurality of sacrificial blocks collectively fit the circular arc-shaped outer circumferential surface of the ingot.
  4. 4. A cutting method according to claim 3, wherein the sacrificial block is made of silicon carbide scrap and has a rectangular cross section perpendicular to the axial direction of the ingot.
  5. 5. The method of claim 4, wherein a gap is formed between two adjacent sacrificial blocks, the gap has a width of 0.5mm to 4mm, and the length of each sacrificial block in the circumferential direction is 5mm to 30mm.
  6. 6. The cutting method as claimed in claim 5, wherein the number of the sacrificial blocks is 3, the sacrificial blocks in the middle are horizontally disposed, and the inclination angles α of the sacrificial blocks on both sides with respect to the sacrificial blocks in the middle satisfy 10 ° - α -20 °.
  7. 7. The cutting method according to any one of claims 1 to 2, wherein the sacrificial component is an integral arc block, the arc block is formed by sintering silicon carbide powder in a mold, a side of the arc block facing the crystal bar is provided with an inward concave arc surface, and the curvature radius of the inward concave arc surface is equal to the curvature radius of the circular arc outer circumferential surface of the crystal bar so as to realize gapless fit.

Description

Cutting method of silicon carbide crystal bar Technical Field The application relates to the technical field of wafer processing, in particular to a cutting method of a silicon carbide crystal bar. Background The Mohs hardness of the silicon carbide is 9.2, the silicon carbide belongs to a superhard material, the hardness is inferior to that of diamond, and the silicon carbide can be cut by a diamond-based tool in the cutting process, so that the cutting speed is very low, and the cutting processing time is longer and longer along with the increase of the diameter of a grown SiC crystal. In addition, the SiC substrate material also requires that the cut wafer must have low warpage and low bending after polishing, and has a low total thickness variation value, thereby further increasing the processing difficulty of the cut silicon carbide wafer. At present, a direct feeding mode is generally adopted in the industry to cut the crystal bar, but the mode has the obvious defects that the feeding speed of a feeding position is higher than that of a middle area due to the characteristic of a cutting process, the hardness of silicon carbide is extremely high, a cutting steel wire is difficult to directly cut into the inside of the crystal bar, axial movement easily occurs outside the crystal bar, the steel wire state is unstable in the cutting process, a deeper line mark with the depth of 50-100 mu m and the maximum radial depth of 10mm is directly generated at a wafer feeding position, the deformation of a wafer in the feeding area is increased, warping is generated, the wafer is directly scrapped due to the fact that the line mark cannot be repaired by a subsequent grinding and polishing process, and the production yield and benefit are seriously affected even if the wafer is reworked according to a Warp value. Disclosure of Invention The application aims to provide a cutting method of a silicon carbide crystal bar, which aims to solve the problem that a wafer generates single-side warpage at a cutter-in position. The cutting method of the silicon carbide crystal bar comprises the following steps of S100, providing a crystal bar to be cut, wherein the crystal bar is provided with an arc-shaped outer peripheral surface extending along the axial direction, S200, determining the cutter inlet top point of the crystal bar in the cutting direction, bonding a sacrificial component at the cutter inlet top point, covering the cutter inlet top point and extending along the axial direction of the crystal bar by the sacrificial component, forming a rigid bonding adhesive layer by the adhesive, S300, controlling a cutting wire net to feed along the direction perpendicular to the axial direction of the crystal bar, enabling the cutting wire net to cut into the sacrificial component first and then cut into the crystal bar, wherein the material of the sacrificial component is the same as that of the crystal bar, or the absolute value of the difference between the Vickers hardness of the sacrificial component and the Vickers hardness of the crystal bar is smaller than a preset threshold value, so that the continuity of cutting stress is kept when the cutting wire net cuts into the crystal bar from the sacrificial component. Preferably, in step S300, the preset threshold is 200HV. As another preference, the thickness H of the sacrificial component in the cutting direction is 3 mm≤H≤10 mm. Further preferably, in step S200, the thickness of the adhesive layer is controlled to be less than 20 μm when the sacrificial member is adhered. Further preferably, the thickness of the adhesive layer is controlled between 2 μm and 10 μm, and the Shore hardness D of the adhesive layer is more than 80. Further preferably, the sacrificial component comprises a plurality of sacrificial blocks arranged along the circumferential direction of the crystal bar, wherein the middle sacrificial blocks cover the cutter inlet peaks, and the sacrificial blocks on two sides are obliquely arranged relative to the middle sacrificial blocks, so that the bottom surfaces of the sacrificial blocks fit the circular arc-shaped peripheral surface of the crystal bar together. Further preferably, the sacrificial block is made of silicon carbide scraps, and has a rectangular cross section perpendicular to the axial direction of the ingot. Further preferably, a gap is formed between two adjacent sacrificial blocks, the width of the gap is 0.5 mm-4 mm, and the length of each sacrificial block along the circumferential direction is 5 mm-30 mm. Further preferably, the number of the sacrifice blocks is 3, the sacrifice blocks in the middle are horizontally arranged, and the inclination angles alpha of the sacrifice blocks on two sides relative to the sacrifice blocks in the middle satisfy that alpha is more than or equal to 10 degrees and less than or equal to 20 degrees. Further preferably, the sacrificial component is an integral arc-shaped block, the arc-shaped block is for