Patent ID: 7972937

Claim:
A method for producing a semiconductor substrate, comprising the steps of: ion-implanting for forming a hydrogen-ion implanted layer to a main surface of a silicon substrate, a surface treatment for performing a plasma-treatment on at least one of a main surface of an insulator substrate, which is any one of a high resistivity silicon substrate, a silicon substrate having an oxide film, a quartz substrate, a sapphire substrate, and a silicon carbide substrate, and the main surface of the silicon substrate, bonding the main surface of the insulator substrate and the main surface of the silicon substrate, delaminating for mechanically delaminating a silicon thin film from the silicon substrate of the bonded substrate to prepare an SOI substrate having a silicon film on the main surface of the insulator substrate, heat-treating the SOI substrate at a temperature of 600° C. to 1250° C., wherein an atmosphere in the heat-treatment is a mixed gas of an oxidizing gas and an inert gas containing as a main component at least one of a nitrogen gas, an argon gas, and a helium gas, thereby gettering metal impurities to a surface region of the silicon film of the SOI substrate, and removing a surface layer of the silicon film of the SOI substrate after the heat-treatment.