Patent ID: 7348257

Claim:
A process for manufacturing a composite wafer, comprising the steps of: providing a first wafer; providing a second wafer having a substrate of semiconductor material; digging a trench in said substrate; forming a top layer of semiconductor material on said substrate so as to close said trench at the top of the deep trench and form a buried cavity; forming a bonding region on a surface of at least one of said first and second wafers; bringing into mutual contact said first and said second wafers, with said top layer of said second wafer facing said first wafer and in contact with said bonding region; and carrying out a thermal treatment so as to cause bonding of a portion of said top layer to said first wafer through said bonding region to provide a bonded portion, and said thermal treatment further widening said buried cavity to form a widened cavity separating the bonded portion of said top layer from the rest of said second wafer, to form a final composite wafer, wherein said first wafer is of semiconductor material and said step of forming a bonding region comprises carrying out a thermal oxidation of the surface of said first wafer.