Patent ID: 7537989

Claim:
A method for manufacturing an SOI substrate comprising a step of partially forming a mask oxide film ( 23 ) on a surface of a silicon substrate ( 12 ), a step of implanting oxygen ions ( 16 ) into the surface of the substrate ( 12 ) through the mask oxide film ( 23 ), and a step of annealing the substrate ( 12 ) to form a buried oxide film ( 13 ) inside the substrate ( 12 ), further comprising: a step of forming a thermally grown oxide film ( 21 ) on a substrate surface ( 12 a ) serving as an SOI area on which the mask oxide film ( 23 ) is not formed between the step of forming the mask oxide film ( 23 ) and the step of implanting the oxide ions ( 16 ) and thereby forming a recess portion ( 12 c ) with a predetermined-depth deeper than a substrate surface ( 12 b ) serving as a bulk area on which the mask oxide film ( 23 ) is formed on the substrate surface ( 12 a ) serving as an SOI area thereof.