Soi wafer and a method for producing the same

A method for producing an SOI wafer comprising at least the steps of:

• forming an oxide film having a thickness of 10 nm-100 nm, at least on one of a base wafer and a bond wafer respectively consisting of silicon single crystal, implanting ions into the bond wafer to form an ion-implanted layer, bonding a surface of an ion-implanted side of the bond wafer and the base wafer via the oxide film, and delaminating the bond wafer at the ion-implanted layer as a boundary, wherein the base wafer is formed of silicon single crystal grown by Czochralski method, and the whole surface of the base wafer is within an N region formed at lower speed than an OSF region generated in a ring shape when grown with gradually decreasing pulling rate from high speed to low speed, and does not include a defect region detected by Cu deposition method, or the whole surface of the base wafer is within a region formed at lower speed than the OSF region generated in a ring shape when grown with gradually decreasing pulling rate from high speed to low speed, does not include the defect region detected by Cu deposition method, and includes an I region containing dislocation cluster due to interstitial silicon.