Patent ID: 7557004

Claim:
A method of manufacturing a semiconductor device including a first transistor formed in a first region of a semiconductor substrate and having a first gate electrode of a first conductive film, a second transistor formed in a second region of the semiconductor substrate and having a second gate electrode of a second conductive film, and a third transistor formed in a third region of the semiconductor substrate and having a third gate electrode of the second conductive film, the method comprising the steps of: forming a first insulating film over the semiconductor substrate; forming the first conductive film over the first insulating film; forming a second insulating film over the first conductive film; removing the second insulating film, the first conductive film and the first insulating film formed in the second region and the third region; forming a third insulating film over the semiconductor substrate in the second region and the third region from which the first insulating film has been removed; removing the second insulating film in the first region and the third insulating film in the third region with a photoresist film covering the second region and exposing the first region and the third region as a mask; forming a fourth insulating film over the semiconductor substrate in the third region from which the third insulating film has been removed; forming the second conductive film over the first conductive film in the first region, the third insulating film in the second region and the fourth insulating film in the third region; patterning the second conductive film and the first conductive film in the first region to form the first gate electrode of the first conductive film; and patterning the second conductive film to form the second gate electrode and the third gate electrode while removing the second conductive film over the first gate electrode.