Patent ID: 8859360

Claim:
A method of manufacturing a semiconductor device including a first n-type MISFET formed in a first region of a semiconductor substrate, a first p-type MISFET formed in a second region of the semiconductor substrate, a second n-type MISFET formed in a third region of the semiconductor substrate and having a thicker gate insulating film than the first n-type MISFET, and a second p-type MISFET formed in a fourth region of the semiconductor substrate and having a thicker gate insulating film than the first p-type MISFET, comprising steps of: (a) forming a gate insulating film of the first n-type MISFET over the first region, and forming a gate insulating film of the first p-type MISFET over the second region; (b) forming a first gate electrode over the gate insulating film of the first n-type MISFET, and forming a second gate electrode over the gate insulating film of the first p-type MISFET; (c) after the step (b), forming first n-type impurity regions in the first region; (d) after the step (b), forming first p-type impurity regions in the second region; (e) after the step (c), forming first sidewall insulating films over the side surfaces of the first gate electrode, and over the side surfaces of the second gate electrode; (f) after the step (e), under a condition which a first resist pattern covers the second region, forming second n-type impurity regions in the first region by ion implantation method, wherein an impurity concentration of each second n-type impurity region is higher than an impurity concentration of each first n-type impurity region; (g) after the step (f), forming second sidewall insulating films over the side surfaces of the first gate electrode via the first sidewall insulating films, and over the side surfaces of the second gate electrode via the first sidewall insulating films; and (h) after the step (g), under a condition which a second resist pattern covers the first region, forming second p-type impurity regions in the second region by ion implantation method, wherein an impurity concentration of each second p-type impurity region is higher than an impurity concentration of each first p-type impurity region.