HIGH MOBILITY MISFET SEMICONDUCTOR DEVICE ON SILICON SUBSTRATE WITH CAVITY AND A METHOD FOR PRODUCING SAME

摘要

A low-cost semiconductor device with low defect density and improved mobility is disclosed which has a high mobility strained silicon structure which enables to realize a high-performance MISFET. As a high mobility strained silicon structure for realizing a high-performance MISFET, a relaxed silicon-germanium film/silicon-germanium film with varying concentration is formed on a silicon substrate with a cavity, and then a strained silicon film is formed thereon. By having such a structure, restraint on the lattices near the cavity is loosened, thereby increasing the degree of freedom. Consequently, the silicon-germanium film can be made thin and thus there can be obtained a low-cost semiconductor device with low defect density and improved mobility.