Patent ID: 6906382

Claim:
A semiconductor device comprising: an element separating area formed on a semiconductor substrate of a first conductivity type; a gate electrode formed on an inner region surrounded by said element separating area on said semiconductor substrate, and having a gate insulating film interposed therebetween; a sidewall spacer formed only on both lateral sides of said gate electrode, and the sidewall spacer is composed of an insulating film; a pair of laminates formed respectively on said semiconductor substrate at both lateral sides of said gate electrode with being in contact with said sidewall spacer, each of said laminates including a lower first semiconductor layer made of silicon and an upper second semiconductor layer mainly made of silicon; and first impurity layers of a second conductivity type, respectively serving as a source or a drain, and respectively formed as extending over both upper areas of said first semiconductor layers and the entire areas of said second semiconductor layers, wherein said first semiconductor layers being made of single-crystal silicon film relatively superior in crystallinity, in that the first semiconductor layers contain substantially no crystal defects, within said inner region, and wherein said second semiconductor layers being made of single-crystal films or polycrystalline films, which are relatively inferior in crystallinity, in that the single-crystal or polvcrystalline films of the second semiconductor layers contain crystal defects, or being made of amorphous films.