Patent ID: 7902043

Claim:
A method of producing a bonded wafer, comprising: performing heat treatment of a first semiconductor wafer and a second semiconductor wafer at a temperature in a range from 1100 to 1150° C. for a retention time in a range from 10 minutes to 2 hours in an Ar gas; performing bonding of the first semiconductor wafer and the second semiconductor wafer after the heat treatment without interposing an insulation film in between; and performing thinning of the second semiconductor wafer, wherein outermost surfaces of the first semiconductor wafer and the second semiconductor wafer before the bonding have an oxygen concentration of not higher than 1.0×10 17 atoms/cm 3 (Old ASTM), and surface portions from the outermost surfaces to the depth of 0.5 μm of the first semiconductor wafer and the second semiconductor wafer have an oxygen concentration of 1.0×10 18 atoms/cm 3 (Old ASTM) or less.