Patent ID: 8294217

Claim:
A method of manufacturing a semiconductor device comprising: ion implanting a first impurity of a first conduction type in a first region of a semiconductor substrate by using a first mask exposing the first region; ion implanting, in a second region of the semiconductor substrate by using a second mask exposing the second region, a second impurity of the first conduction type, whose diffusion constant is smaller than the first impurity or the first impurity and a third impurity which suppresses a diffusion of the first impurity; activating the first impurity and the second impurity to form a first impurity layer in the first region and a second impurity layer in the second region; epitaxially growing a semiconductor layer above the semiconductor substrate with the first impurity layer and the second impurity layer formed in; forming a first gate insulating film above the semiconductor layer in the first region and the second region; removing the first gate insulating film in the second region by using a third mask exposing the second region; forming a second gate insulating film thinner than the first gate insulating film above the semiconductor layer in the second region; and forming a first gate electrode above the first gate insulating film and a second gate electrode above the second gate insulating film.