Patent ID: 8354326

Claim:
A method for manufacturing a semiconductor device, comprising: forming an oxide film on a semiconductor substrate; forming a polysilicon film with an opening on the oxide film; forming a first oxygen-containing region in the semiconductor substrate by implanting oxygen ions to the semiconductor substrate using the polysilicon with the opening as a mask; forming a second oxygen-containing region by implanting oxygen ions to the polysilicon film; oxidizing the first oxygen-containing region and the second oxygen-containing region using oxygen contained therein by performing a thermal processing of the first oxygen-containing region and the second oxygen-containing region, wherein the first oxygen-containing region is converted to a first oxide region, and the second oxygen-containing region is converted to a second oxide region; and forming a groove in the semiconductor substrate by eliminating the first oxide region and the second oxide region, wherein the performing thermal processing comprises subjecting the first oxygen-containing region and the second oxygen-containing region to a gas low on oxygen.