Patent ID: 7696059

Claim:
A method for manufacturing a semiconductor substrate comprising: an ion implantation step of forming a hydrogen ion implanted layer to a main surface of a silicon substrate; a surface treatment step of performing a plasma treatment with respect to a main surface of at least one of a transparent insulator substrate and the silicon substrate; a step of bonding the main surfaces of the transparent insulator substrate and the silicon substrate to each other; a delamination step of mechanically delaminating a silicon thin film from the silicon substrate of the bonded substrate to provide an SOI substrate having a silicon film on the main surface of the transparent insulator substrate; a step of performing a flattening treatment with respect to the silicon film of the SOI substrate; a step of thermally oxidizing the flattened surface of the silicon film at a temperature of 450° C. or below to form an oxide film of 100 Å or below; and a step of depositing an oxide film on the thermal oxide film based on a CVD method to form a gate oxide film.