Patent ID: 7910455

Claim:
A method for producing a SOI wafer, comprising at least the steps of: preparing a base wafer and a bond wafer each made of silicon single crystal; forming an insulator film on a surface of at least one of the base wafer and the bond wafer; bonding the base wafer and the bond wafer via the insulator film to form a bonded wafer; a bonding heat treatment for increasing bonding strength by heat-treating the bonded wafer at a treatment temperature; and thinning the bond wafer, wherein argon is ion-implanted into a first surface, wherein the first surface is on either the base wafer or the bond wafer at a dosage of 1×10 15 atoms/cm 2 or more to form a layer that is ion-implanted with the argon, before the bonding step, the first surface ion-implanted with argon is used as a bonding surface in the bonding step, a rate of increase in temperature to the treatment temperature of the bonding heat treatment is 5° C./minute or higher, and the layer that is ion-implanted with the argon grows to be a polycrystal and forms a polycrystalline silicon layer in the SOI wafer.