Method of producing SiC wafer

Patent metadata

Field	Value
Publication number	US-9975202-B2
Application number	US-201715678785-A
Country	US
Kind code	B2
Filing date	Aug 16, 2017
Priority date	Aug 29, 2016
Publication date	May 22, 2018
Grant date	May 22, 2018

Abstract

An SiC wafer is generated from an SiC ingot by a peel-off plane generating step for generating a peel-off plane by forming a separation layer made up of a modified layer, and cracks extending from the modified layer along a c-plane, a plurality of times by indexing-feeding a focused point of a pulsed laser beam and the SiC ingot relative to each other in a direction in which an off-angle is formed, thereby forming a plurality of separation layers to generate the peel-off plane. The peel-off plane generating step includes relatively moving the focused point from an end to an opposite end of the SiC ingot in a forward stroke and relatively moving the focused point from the opposite end to the end of the SiC ingot in a backward stroke to trace back the separation layer that has already been formed in the forward stroke.

First claim

What is claimed is:

1. A method of producing an SiC wafer from a single-crystal SiC ingot having a first surface, a second surface opposite the first surface, a c-axis extending from the first surface to the second surface and oblique to a line perpendicular to the first surface, and a c-plane perpendicular to the c-axis, the c-plane and the first surface jointly defining an off-angle therebetween, comprising:
a peel-off plane forming step of forming a peel-off plane in the SiC ingot by performing a separation layer forming step by positioning a focused point of a pulsed laser beam having a wavelength with which SiC is transmittable in the SiC ingot at a depth, from the first surface, corresponding to the thickness of a wafer to be produced from the SiC ingot, and applying a pulsed laser beam to the SiC ingot while the SiC ingot and the focused point are relatively processing-fed in a first direction perpendicular to a second direction in which the off-angle is formed, thereby forming a separation layer made up of a modified layer where SiC is separated into Si and C by a pulsed laser beam applied thereto and a pulsed laser beam applied next thereto is absorbed by the previously formed C, separating SiC into Si and C in a chain reaction, and cracks extending from the modified layer along the c-plane, the separation layer forming step being performed a plurality of times by indexing-feeding the SiC ingot and the focused point relatively to each other in the second direction in which the off-angle is formed, thereby forming a plurality of separation layers to form the peel-off plane; and
a wafer producing step of peeling off a portion of the SiC ingot from the peel-off plane that serves as a boundary plane, as an SiC wafer;
wherein the peel-off plane forming step includes relatively moving the focused point from an end to an opposite end of the SiC ingot in a forward stroke and relatively moving the focused point from the opposite end to the end of the SiC ingot in a backward stroke to trace back the separation layer that has already been formed in the forward stroke.

Assignees

• Disco Corp

Inventors

• Yamamoto Ryohei
• Hirata Kazuya

Classifications

• B23K26/53 Primary

  for modifying or reforming the material inside the workpiece, e.g. for producing break initiation cracks · CPC title

• B28D5/0011

  with preliminary treatment, e.g. weakening by scoring · CPC title

• B23K26/0006

  taking account of the properties of the material involved (B23K26/32, B23K26/40 take precedence) · CPC title

• B23K26/0853

  Devices involving movement of the workpiece in at least two axial directions, e.g. in a plane · CPC title

• B23K2203/56

  Operations & Transport · mapped topic