Patent ID: 7625808

Claim:
A method for manufacturing a bonded wafer, comprising: ion-implanting a light element into a wafer for active layer at a predetermined depth via an insulating film that has been formed thereon to form an ion-implanted area in said active layer wafer; subsequently bonding said active layer wafer with a supporting wafer having an insulating film formed thereon together as their insulating films facing to each other to produce the bonded wafer; and heat treating said bonded wafer to form bubbles of said light element in said ion-implanted area and thereby induce a cleavage and separation of a part of said bonded wafer defined in said ion-implanted side for forming an active layer wherein a thickness of said insulating film of said active layer wafer, tdox, satisfies the following formula: tdox <( 1/9)× tsoi, where tsoi=thickness of said active layer, and wherein the thickness of said active layer is approximately 333 nm or less.