Patent ID: 8796779

Claim:
A semiconductor device comprising: a first MIS transistor and a second MIS transistor of an identical conductivity type provided on an identical semiconductor substrate, wherein the first MIS transistor includes a first gate insulating film formed on a first active region in the semiconductor substrate and a first gate electrode formed on the first gate insulating film, the second MIS transistor includes a second gate insulating film formed on a second active region in the semiconductor substrate and a second gate electrode formed on the second gate insulating film, the first gate insulating film includes a first interface layer being in contact with the semiconductor substrate and a first high dielectric constant insulating film formed on the first interface layer, the second gate insulating film includes a second interface layer being in contact with the semiconductor substrate and a second high dielectric constant insulating film formed on the second interface layer, the first interface layer has a thickness larger than that of the second interface layer, and each of the first interface layer and the second interface layer is made of a silicon dioxide film or a silicon oxynitride film.