Patent ID: 8481383

Claim:
A method of manufacturing a semiconductor device comprising: forming a first gate electrode on a first gate insulating film above a first channel area in a silicon substrate; forming a second gate electrode on a second gate insulating film above a second channel area in the silicon substrate; forming P type diffusion areas in the silicon substrate by using the second gate electrode as a mask; forming a first insulating film over the first gate electrode and the second gate electrode; removing the first insulating film over the first gate electrode while having the first insulating film remain over the second gate electrode; after removinq the first insulating film over the first date electrode, annealing the first insulating film remaining over the second gate electrode by using a gas including a nitrogen element; after the annealing, forming first sidewall insulating films on sidewalls of the first gate electrode; after the annealing, forming second sidewall insulating films on the first insulating film remaining over the second gate electrode; forming N type diffusion areas in the silicon substrate by using the first gate electrode and the first sidewall insulating films as a mask; and forming P type diffusion areas in the silicon substrate by using the second gate electrode, the first insulating film remaining over the second gate electrode and the second sidewall insulating films as a mask; wherein the distance between the second sidewall insulating films and the silicon substrate is greater than the distance between the first sidewall insulating films and the silicon substrate.