Fabrication of mixed thin-film and bulk semiconductor substrate for integrated circuit applications

摘要

A mixed thin-film and bulk semiconductor substrate (10, 30) for integrated circuit applications is made with two different processes. In the first process, a standard wafer (11) is masked around its periphery (14). The internal unmasked portion (16) is implanted with an insulating species to form a buried dielectric layer (18), thus forming a mixed thin- film and bulk semiconductor substrate. Alternatively, a thin- film wafer may be masked on an internal portion (36) and then etched to expose a portion (40) of the underlying bulk substrate (11') around the periphery of the wafer. An epitaxial layer (50) is then grown to build up the exposed bulk portion to form the mixed substrate. An isolation region (24, 52, 46, 54) is formed at a boundary between the thin-film portion and the bulk portion. Devices (27, 28, 28') having different voltage requirements may then be formed overlying appropriate portions of the mixed substrate.