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CN-118219164-B - Wafer polishing method and wafer polishing apparatus

CN118219164BCN 118219164 BCN118219164 BCN 118219164BCN-118219164-B

Abstract

The application provides a wafer grinding method and wafer grinding equipment, wherein the wafer grinding method comprises the steps of placing a wafer on the surface of a wafer carrying disc of the wafer grinding equipment, obtaining preset fine grinding parameters, wherein the fine grinding parameters comprise the rotating speed n1 of a grinding wheel of the wafer grinding equipment and the rotating speed n2 of the wafer carrying disc when the wafer is subjected to fine grinding, and controlling the grinding wheel and the wafer carrying disc to rotate based on the fine grinding parameters so as to grind the surface of the wafer through a grinding part of the grinding wheel, wherein the rotating directions of the grinding wheel and the wafer carrying disc are the same when the wafer is subjected to fine grinding, and the fine grinding parameters meet the requirement that n2/n1 is equal to 0.1+/-0.025. The application improves the uniformity of the surface roughness distribution after the wafer is ground, and can meet the processing requirement of products with higher roughness requirements.

Inventors

  • ZHANG LINXI
  • LIU CHANGCHANG
  • ZHANG XUEAN

Assignees

  • 上海积塔半导体有限公司

Dates

Publication Date
20260512
Application Date
20240506

Claims (10)

  1. 1. A method of polishing a wafer, comprising: placing a wafer on the surface of a wafer carrying disc of wafer grinding equipment; Acquiring preset fine grinding parameters, wherein the fine grinding parameters comprise the rotating speed n1 of a grinding wheel of the wafer grinding equipment and the rotating speed n2 of the wafer carrying disc when the wafer is subjected to fine grinding; Controlling the grinding wheel and the wafer carrying disc to rotate based on the fine grinding parameters so as to grind the surface of the wafer through a grinding part of the grinding wheel, wherein the rotation directions of the grinding wheel and the wafer carrying disc are the same when the wafer is subjected to fine grinding, and the fine grinding parameters meet that n2/n1 is equal to 0.1+/-0.025; wherein the grinding force of the grinding wheel satisfies the following formula: ; Wherein F t is the grinding force of a grinding part, R 2 is the wafer radius, F t is the grinding force of a single abrasive, N e is the effective cutting edge density, l is the length of the grinding part, w is the width of the grinding part, R 1 is the grinding wheel radius, cp is the set grinding pressure, N 1 is the grinding wheel rotation speed, N 2 is the wafer carrier disc rotation speed, and delta is the grinding depth.
  2. 2. The method according to claim 1, wherein the rotational speed n1 of the grinding wheel is 2000rpm ± 500rpm when the wafer is subjected to finish grinding.
  3. 3. The method according to claim 2, wherein the rotation speed n2 of the wafer carrier is 200 rpm ±50rpm when the wafer is subjected to finish polishing.
  4. 4. The method of claim 2, wherein the rotational speed n1 of the grinding wheel is 2000rpm and the rotational speed n2 of the wafer carrier is 200rpm.
  5. 5. The method of claim 1, further comprising the steps of, prior to the obtaining the predetermined finish polishing parameters: Acquiring preset rough grinding parameters, wherein the rough grinding parameters comprise the rotating speed of the grinding wheel and the rotating speed of the wafer carrying disc when the wafer is subjected to rough grinding; and controlling the grinding wheel and the wafer carrying disc to rotate based on the rough grinding parameters so as to grind the surface of the wafer through a grinding part of the grinding wheel.
  6. 6. The method according to claim 5, wherein the grinding wheel and the wafer carrier are rotated in the same direction and the rotation speed of the grinding wheel is greater than n1 when the wafer is rough-ground.
  7. 7. The method of claim 6, wherein the rotational speed of the grinding wheel is 3000 rpm ±500rpm when the wafer is rough ground.
  8. 8. The method for polishing a wafer according to claim 1, wherein the wafer for polishing a silicon carbide substrate is polished.
  9. 9. A wafer polishing apparatus, comprising: The wafer bearing disc is used for bearing wafers; The grinding wheel comprises a plurality of grinding parts, wherein the grinding parts are arranged on one side of the grinding wheel facing the wafer carrying disc and are used for grinding the wafers on the wafer carrying disc; the first driving mechanism and the second driving mechanism respectively drive the grinding wheel and the wafer carrying disc to rotate based on preset fine grinding parameters so as to grind the surface of the wafer through a grinding part of the grinding wheel, wherein the fine grinding parameters comprise a rotating speed n1 of the grinding wheel and a rotating speed n2 of the carrying disc when the wafer is subjected to fine grinding; When the wafer is subjected to finish grinding, the grinding wheel and the wafer bearing disc rotate in the same direction, and the finish grinding parameters meet that n2/n1 is equal to 0.1+/-0.025; wherein the grinding force of the grinding wheel satisfies the following formula: ; Wherein F t is the grinding force of a grinding part, R 2 is the wafer radius, F t is the grinding force of a single abrasive, N e is the effective cutting edge density, l is the length of the grinding part, w is the width of the grinding part, R 1 is the grinding wheel radius, cp is the set grinding pressure, N 1 is the grinding wheel rotation speed, N 2 is the wafer carrier disc rotation speed, and delta is the grinding depth.
  10. 10. The wafer polishing apparatus according to claim 9, wherein a rotational speed n1 of the polishing wheel is 2000rpm±500rpm and a rotational speed n2 of the wafer carrier plate is 200 rpm ±50rpm when the wafer is subjected to finish polishing.

Description

Wafer polishing method and wafer polishing apparatus Technical Field The application relates to the technical field of semiconductor preparation, in particular to a wafer grinding method and wafer grinding equipment. Background Currently, conductive silicon carbide SiC substrates are limited to wafer processing, and concentration spot areas can appear on the back side of the substrate. As shown in fig. 1, there is a concentration spot area 110 with chromatic aberration on the back surface of the wafer substrate 100 (flat side facing upwards), and the presence of the concentration spot area 110 affects the roughness uniformity of the polished surface of the wafer, which is specifically shown by that the local roughness corresponding to the concentration spot area is lower after the substrate is polished and thinned. The wafer polishing mainly uses an In-Feed method, and most of the polishing uses a method of z1+z2 (rough polishing+fine polishing). Since some semiconductor products require a relatively high roughness (Ra >10 nm) on the back side (or C side) of the silicon carbide substrate, grinding wheels of the same grit SD2000 are used in the rough grinding + finish grinding stage. In the finish grinding stage, if the grinding wheel speed is 3000rpm, as shown in fig. 2, the overall roughness is too low to meet the product requirements. Therefore, the rotation speed of the grinding wheel can be reduced to 2000rpm in the finish grinding stage to enable the roughness to meet the requirement, however, at the moment, the roughness of a local area of the substrate is influenced by concentration spots, as shown in fig. 3, the roughness of the concentration spot area is lower, other potential product risks such as peeling of the back Jin Yi and fluctuation of electrical parameters are easily caused, and the problem of roughness distribution is difficult to improve by a wet etching method after the SiC substrate is ground due to stable chemical properties. Therefore, it is desirable to provide a wafer polishing method to overcome the problem of poor overall roughness uniformity caused by too low local surface roughness after wafer polishing. It should be noted that the information disclosed in the foregoing background section is only for enhancement of understanding of the background of the application and thus may include information that does not form the prior art that is already known to those of ordinary skill in the art. Disclosure of Invention Aiming at the problems in the prior art, the application aims to provide a wafer grinding method and wafer grinding equipment, which improve the roughness of a concentration spot position, ensure that the roughness uniformity of an overall wafer after grinding is higher, ensure the average value of the roughness, and meet the processing requirement of products with higher roughness requirements. The embodiment of the application provides a wafer grinding method, which comprises the following steps: placing a wafer on the surface of a wafer carrying disc of wafer grinding equipment; Acquiring preset fine grinding parameters, wherein the fine grinding parameters comprise the rotating speed n1 of a grinding wheel of the wafer grinding equipment and the rotating speed n2 of the wafer carrying disc when the wafer is subjected to fine grinding; and controlling the grinding wheel and the wafer carrying disc to rotate based on the fine grinding parameters so as to grind the surface of the wafer through a grinding part of the grinding wheel, wherein the rotation directions of the grinding wheel and the wafer carrying disc are the same when the wafer is subjected to fine grinding, and the fine grinding parameters meet that n2/n1 is equal to 0.1+/-0.025. In some embodiments, the rotational speed n1 of the grinding wheel is 2000rpm + -500 rpm when the wafer is finish ground. In some embodiments, the rotational speed n2 of the wafer carrier plate is 200rpm + -50 rpm when the wafer is finish ground. In some embodiments, the rotational speed n1 of the grinding wheel is 2000rpm and the rotational speed n2 of the wafer carrier plate is 200rpm. In some embodiments, before the obtaining the preset fine grinding parameters, the method further includes the following steps: Acquiring preset rough grinding parameters, wherein the rough grinding parameters comprise the rotating speed of the grinding wheel and the rotating speed of the wafer carrying disc when the wafer is subjected to rough grinding; and controlling the grinding wheel and the wafer carrying disc to rotate based on the rough grinding parameters so as to grind the surface of the wafer through a grinding part of the grinding wheel. In some embodiments, the grinding wheel and the wafer carrier are rotated in the same direction and the rotational speed of the grinding wheel is greater than n1 when the wafer is rough ground. In some embodiments, the rotational speed of the grinding wheel is 3000rpm + -500 rpm when the wafer is roug