Patent ID: 8907430

Claim:
A semiconductor device comprising: a first transistor including a first gate side wall insulating film and a second gate side wall insulating film disposed outside of the first gate side wall insulating film; a second transistor including a third gate side wall insulating film that has the same composition as a composition of the first gate side wall insulating film, and a fourth gate side wall insulating film that has the same composition as a composition of the second gate side wall insulating film, the fourth gate side wall insulating film being disposed outside of the third gate side wall insulating film; and a third transistor including a fifth gate side wall insulating film that has the same composition as the composition of the second gate side wall insulating film and the fourth gate side wall insulating film, wherein a total side wall spacer width of the third transistor is smaller than a total side wall spacer width of the second transistor by a thickness corresponding to the third gate side wall insulating film; wherein the first transistor is a flash memory; wherein the second transistor is configured to operate at a higher voltage than the third transistor; wherein each of the first gate side wall insulating film and the third gate side wall insulating film contains a first silicon oxide film and a first silicon nitride film which is disposed outside of the first silicon oxide film; wherein each of the second gate side wall insulating film, the fourth gate side wall insulating film, and the fifth gate side wall insulating film contains a second silicon oxide film and a second silicon nitride film which is disposed outside of the second silicon oxide film; and wherein the first silicon oxide film has a higher density than the second silicon oxide film, and the first silicon nitride film has a higher density than the second silicon nitride film.