Patent ID: 8048769

Claim:
A method for producing a bonded wafer by directly bonding a wafer for active layer to a wafer for support layer and then thinning the wafer for active layer, which comprises a time-oriented combination of: implanting oxygen ions into the wafer for active layer to form an oxygen ion implanted layer in the active layer; subjecting the wafer for active layer to a heat treatment at a temperature of not lower than 1100° C. in a non-oxidizing atmosphere; bonding the wafer for active layer to a wafer for support layer; heat-treating for improving a bonding strength; grinding a portion of the wafer for active layer in the bonded wafer that does not include of the oxygen ion implanted layer; further polishing or etching the wafer for active layer to expose the oxygen ion implanted layer; oxidizing the bonded wafer to form an oxide film on the exposed surface of the oxygen ion implanted layer; removing the oxide film; and heat-treating at a temperature of not higher than 1100° C. in a non-oxidizing atmosphere.