Patent ID: 7517760

Claim:
A method for manufacturing a semiconductor device which includes: a first active region, a second active region, and a third active region which are formed in a semiconductor substrate and are separated from one another by element isolation regions; a first gate electrode formed on the first active region with a first gate insulating film interposed; a second gate electrode formed on the second active region with a second gate insulating film thinner than the first gate insulating film interposed; and a third gate electrode formed on the third active region with a third gate insulating film thinner than the second gate insulating film interposed, the method comprising: a step (a) of forming protective insulating films on the first active region, the second active region, and the third active region; a step (b) of removing the protective insulating films formed on the first active region and the third active region; a step (c) of forming, after the step (b), an insulating film to be the first gate insulating film on each of the first active region and the third active region; a step (d) of removing, after the step (c), the protective insulating film formed on the second active region; a step (e) of forming, after the step (d), an insulating film to be the second gate insulating film on the second active region; a step (f) of removing, after the step (e), the insulating film to be the first gate insulating film formed on the third active region; and a step (g) of forming, after the step (f), an insulating film to be the third gate insulating film on the third active region.