Method for evaluating internal stress of silicon carbide monocrystalline wafer and method for predicting warpage in silicone carbide monocrystalline wafer

Patent metadata

Field	Value
Publication number	US-2016231256-A1
Application number	US-201415023254-A
Country	US
Kind code	A1
Filing date	May 30, 2014
Priority date	Sep 20, 2013
Publication date	Aug 11, 2016
Grant date	—

Abstract

Provided are a method of evaluating an internal stress of a silicon carbide (SiC) single crystal wafer and a method of predicting warpage of the SiC single crystal wafer after completion of polishing by evaluating the internal stress of the wafer. Wavenumber shift amounts of Raman-scattered light are measured at two points within a surface of the SiC single crystal wafer, and the internal stress is evaluated through use of a difference between the wavenumber shift amounts. Also provided is a method of predicting warpage of a silicon carbide single crystal wafer in advance, the silicon carbide single crystal wafer being produced by sublimation-recrystallization method, the method including predicting warpage of a SiC single crystal wafer through use of the evaluation indicator.

First claim

1 . A method of evaluating an internal stress of a silicon carbide single crystal wafer, the silicon carbide single crystal wafer being produced by a sublimation-recrystallization method, through use of a difference between Raman shift values measured at two points within a principal surface of the silicon carbide single crystal wafer.

2 . A method of evaluating an internal stress of a silicon carbide single crystal wafer according to claim 1 , the method comprising using a Raman shift difference (A-B) between a Raman shift value (A) measured at a center and a Raman shift value (B) measured in an outer peripheral portion.

3 . A method of predicting warpage of a silicon carbide single crystal wafer in advance, the silicon carbide single crystal wafer being produced by a sublimation-recrystallization method,
the method comprising estimating warpage of the silicon carbide single crystal wafer after completion of a polishing step through use of a difference between Raman shift values at two points within any one of a front surface and a back surface, which is measured before final polishing in obtaining the silicon carbide single crystal wafer.

4 . A method of predicting warpage of a silicon carbide single crystal wafer according to claim 3 , the method comprising using a difference between Raman shift values measured at two points within any one of a front surface and a back surface of a single crystal thin plate obtained by slicing a silicon carbide single crystal ingot obtained by the sublimation-crystallization method.

5 . A method of predicting warpage of a silicon carbide single crystal wafer according to claim 3 or 4 , the method comprising: determining, in advance, a relationship between the difference between the Raman shift values and the warpage of the silicon carbide single crystal wafer; and predicting, based on an obtained relational expression, the warpage of the silicon carbide single crystal wafer from the difference between the Raman shift values.

Assignees

• Nippon Steel & Sumikin Mat Co

Inventors

• Kojima Kiyoshi
• Nakabayashi Masashi
• Shimomura Kota
• Nagahata Yukio

Classifications

• H10P74/203

  Structural properties, e.g. testing or measuring thicknesses, line widths, warpage, bond strengths or physical defects · CPC title

• G01L1/24

  by measuring variations of optical properties of material when it is stressed, e.g. by photoelastic stress analysis {using infrared, visible light, ultraviolet} · CPC title

• C30B29/36

  Carbides · CPC title

• G01N2201/06113

  Coherent sources; lasers · CPC title

• G01N21/65 Primary

  Raman scattering · CPC title