Process used to fabricate bonded SOI substrates by cleaving the top wafer close to the desired thickness of the active layer. Before bonding, one wafer is implanted with hydrogen to a depth that will determine the thickness of an active layer in the future SOI wafer;following bonding, the wafer is annealed (at ~500ºc) at which time the wafer splits along the plane stressed with implanted hydrogen. The result is a very thin layer of Si forming a SOI substrate.