Patent ID: 8035174

Claim:
A semiconductor device comprising: a semiconductor substrate; a first dielectric film formed on the semiconductor substrate; a second dielectric film formed on the first dielectric film and having a higher permittivity than the first dielectric film; a gate electrode formed on the second dielectric film, both end portions of the gate electrode in the gate length direction projecting out from the second dielectric film with an eave shape; a third dielectric film formed between the both end portions of the gate electrode projecting out with an eave shape and the semiconductor substrate and having a lower permittivity than the second dielectric film; and a source region and a drain region formed in parts of the semiconductor substrate lateral to the gate electrode, wherein both end portions of the first dielectric film and the second dielectric film in the gate length direction are located inwardly of the both end portions of the gate electrode in the gate length direction, the second dielectric film is not in contact with an entire surface of a portion of the semiconductor substrate located immediately below the gate electrode, an extreme end of the source region located near the gate electrode and an extreme end of the drain region located near the gate electrode are located inwardly of both side surfaces of the gate electrode in the gate length direction and located outwardly of both side surfaces of the second dielectric film in the gate length direction, an entirety of a lower surface of the gate electrode is substantially flat, and a lowest upper surface of a portion of the semiconductor substrate located under the third dielectric film is lower than a highest upper surface of a portion of the semiconductor substrate located under the first dielectric film.