Patent ID: 6953728

Claim:
A method of manufacturing a semiconductor device comprising the steps of: (a) forming first and second well each having a n-type conductivity in a semiconductor substrate, (b) forming third and fourth well each having a p-type conductivity in the semiconductor substrate; (c) forming a first gate insulation film on the first well, a second gate insulation film on the second well, a third gate insulation film on the third well and a fourth gate insulation film on the fourth well, wherein the first and third gate insulation film are thicker than the second and fourth gate insulation film; (d) applying oxynitridation to the first, second, third and fourth gate insulation film; (e) forming a first gate electrode of a first MISFET on the first gate insulation film, a second gate electrode of a second MISFET on the second gate insulation film, a third gate electrode of a third MISFET on the third gate insulation film and a fourth gate electrode of a fourth MISFET on the fourth gate insulation film; (f) implanting an ion that contains nitrogen or nitrogen atoms, using a resist mask having a opening at a forming region of the third MISFET, and after the step (e); and (g) forming a first extension region of the first MISFET, a second extension region of the second MISFET, a third extension region of the third MISFET, and a fourth extension region of the fourth MISFET, after the step (f).