Patent ID: 8232608

Claim:
A semiconductor device with a high-voltage transistor and a low-voltage transistor, comprising: an isolation insulating film between a first element region of the high-voltage transistor and a second element region of the low-voltage transistor; a first gate insulating film on a semiconductor substrate in the first element region; a first gate electrode on the first gate insulating film; a second gate insulating film on the semiconductor substrate in the second element region; and a second gate electrode on the second gate insulating film, wherein the isolation insulating film comprises a first isolation region adjacent to the first element region and a second isolation region adjacent to the second element region, a bottom of the second isolation region being lower than a bottom of the first isolation region, and the first gate insulating film being thicker than the second gate insulating film, wherein a top of the first gate insulating film is flush with a top of the second gate insulating film.