Patent ID: 7666758

Claim:
A process for fabricating a silicon on insulator (SOI) substrate which comprises: forming a weakened zone within a semiconductor donor substrate to define a thick layer having a thickness of greater than 150 nm and form a boundary between the thick layer and a remainder of the donor substrate; bonding the donor substrate to a semiconductor receiver substrate, with one of the substrates including an oxide layer that is present between the donor and receiver substrate after bonding; detaching a remainder of the donor substrate along the weakened zone to obtain a semifinished SOI substrate comprising the receiver substrate, the oxide layer and the thick layer; and finishing the semifinished SOI substrate by: thinning the thick layer to obtain a thin layer having an exposed surface and a thickness is less than that of the thick layer but greater than 150 nm; long annealing the exposed surface of the thin layer of the semifinished SOI substrate in a gaseous atmosphere comprising hydrogen, argon or a mixture thereof, wherein the long anneal is conducted after thinning the thick layer; and thinning the thin layer to obtain an ultrathin layer having a thickness of 150 nm or less after long annealing the thin layer, thus obtaining the finished substrate.