Atomic-layer cleaving with Si/sub x/Ge/sub y/ strain layers for fabrication of Si and Ge-rich SOI device layers

Methods to fabricate multi-layer SOI structures have evolved from epitaxial growth of Si on sapphire and grind-back of bonded layers (in the 1970s) to direct implantation of oxygen (SIMOX) and etching of bonded wafers (from the 1980s) to bonded processes that exploit fracture of porous layers by thermal (ion/Smart-cut) or mechanical (Eltran) stress (in the 1990s). The recent development of controlled cleaving techniques using, engineered SiGe strain layers (NanoCleave/sup TM/) in conjunction with advances in layer bonding and thickness modification results in marked improvements in film thickness control. film and surface quality and production efficiency over earlier methods.