Patent ID: 8222124

Claim:
A method for manufacturing a SIMOX wafer where a BOX layer composed of silicon oxide is locally formed in an interior of a silicon single crystal wafer, the method comprising: forming a mask layer on one surface side of a silicon single crystal wafer, which has an opening on a region where a BOX layer is to be formed; implanting oxygen ions through the opening of the mask layer into the silicon single crystal wafer to a predetermined depth, and locally forming an oxygen implantation region; annealing the silicon single crystal wafer with the mask layer, and oxidizing the oxygen implantation region so as to form the BOX layer; and removing a coated oxide film that covers the whole silicon single crystal wafer which is formed in the annealing of the silicon single crystal wafer, wherein the mask layer is composed of a first silicon oxide film, either one or both of a polysilicon film and an amorphous silicon film, and a second silicon oxide film, which are laminated in this order from the one surface side of the silicon single crystal wafer, and wherein the method further comprises removing the second silicon oxide film from the mask layer between the implanting of the oxygen ions and the annealing of the silicon single crystal wafer.