A method for forming an integrated circuit on an insulating substrate is described
comprising the steps of forming a semiconductor layer on a seed wafer substrate
containing an at least partially crystalline porous release layer, processing the
semiconductor layer to form a "transferable" device layer containing at least one
semiconductor device, and bonding said transferable device layer to a final, insulating
substrate before or after separating said device layer from the seed wafer substrate.
A second method, for separating a semiconductor layer from a seed wafer substrate,
is described wherein an at least partially crystalline porous layer initially connecting
the semiconductor layer and seed wafer substrate is split or broken apart by the
steps of (i) introducing a fluid including water into the pores of said porous
layer, and (ii) expanding said fluid by solidifying or freezing to break apart
the porous layer. The at least partially crystalline porous layer may incorporate
at least one porous silicon germanium alloy layer alone or in combination with
at least one porous Si layer. Also described is an integrated circuit comprising
the transfered device layer described above.