Patent ID: 8143668

Claim:
A semiconductor device comprising: (a) a pair of source/drain regions formed of a semiconductor layer and arranged on a main surface of a semiconductor substrate at a predetermined distance therebetween; (b) sidewall insulating films arranged to be adjacent to sidewalls of the source/drain regions; (c) a gate electrode arranged at a position between the pair of the source/drain regions and sandwiched by the sidewall insulating films via an interposed gate insulating film, in a cross-sectional view; and (d) first semiconductor regions formed in regions each extending from respective a position below and lateral to the gate electrode to a position overlapping with an end portion of a corresponding one of the source/drain regions in the cross-sectional view, wherein the first semiconductor regions are formed to be electrically connected to the source/drain regions, impurity concentrations of the first semiconductor regions are lower than impurity concentrations of the source/drain regions, each of said sidewalls of the source/drain regions has a shape such that a height thereof from the semiconductor substrate becomes lower toward an end portion thereof, and each of the sidewall insulating films has a sidewall which is adjacent to the gate insulating film and the gate electrode, and which has a shape such that a height thereof from the semiconductor substrate becomes lower toward an end portion thereof, a trench-shaped recess portion is disposed at a position between the pair of source/drain regions and sandwiched by the sidewall insulating films in the cross-sectional view, the gate insulating film and the gate electrode are formed to cover the recess portion, a dielectric constant of the gate insulating film is higher than that of silicon oxide, the gate electrode is formed of a conductor film mainly made of titanium nitride, molybdenum nitride, or hafnium silicide, and each of the source/drain regions is formed of a semiconductor layer mainly made of a mixed crystal of silicon and germanium.