Patent ID: 9303332
Filing Date: 2016-04-05
CPC Classification: C30B

Claim Text:
1. A method of manufacturing a silicon single crystal substrate, comprising the steps of: preparing an initial silicon melt having a boron concentration and a phosphorous concentration, said boron concentration being not higher than 4×10 growing a silicon single crystal by the Czochralski method from said initial silicon melt; and slicing said silicon single crystal to form a silicon single crystal substrate; wherein in said step of growing said silicon single crystal, said silicon single crystal is grown under conditions such that a ratio of the rate of cooling of an edge portion of the silicon single crystal to a rate of cooling a central portion of the silicon single crystal from the melting point of silicon to 1350° C. is not lower than 1.4 and not higher than 2.0, and the rate of cooling the central portion from 1200° C. to 1100° C. is not less than 6° C./minute, said silicon single crystal having an oxygen concentration not lower than 5.0×10