Patent ID: 8709911

Claim:
A method for producing an SOI substrate in which an SOI layer having a thickness of 1 μm or more is formed on a buried oxide film by a bonding method, comprising at least the steps of: preparing a bond wafer and a base wafer which are composed of single crystal silicon wafers; forming an oxide film on a surface of at least one of the bond wafer and the base wafer so that a thickness of a buried oxide film after bonding becomes 3 μm or more; bonding the bond wafer and the base wafer via the oxide film; and performing the following steps in the following sequential order: (1) performing a low-temperature heat treatment at a temperature of 400° C. or more and 1000° C. or less to the substrate made by bonding the bond wafer and the base wafer; (2) thinning the bond wafer to be an SOI layer, the thinning of the bond wafer being performed only by grinding, or only by polish, or only by grinding and polishing; and (3) increasing bonding strength by performing a high-temperature heat treatment at a temperature exceeding 1000° C.