Patent ID: 8384187

Claim:
A semiconductor device comprising: a first shallow trench isolation having a prescribed depth and a first width so as to surround a first region in the semiconductor substrate; a second shallow trench isolation having a prescribed depth and a second width narrower than the first width so as to surround a second region in the semiconductor substrate; a first element isolation insulating film embedded in the first shallow trench isolation; and a second element isolation insulating film embedded in the second shallow trench isolation, wherein: the second element isolation insulating film includes: a first insulating film having a prescribed density; and a second insulating film having a density higher than the density of the first insulating film; in the second shallow trench isolation, the first insulating film and the second insulating film are embedded so that the second insulating film is stacked over the first insulating film; and the first element isolation insulating film includes the first insulating film and does not include the second insulating film.