Patent ID: 7148552

Claim:
A semiconductor device comprising: a high breakdown voltage transistor and a low voltage transistor the widths of whose side walls are different from each other; the side walls of the high breakdown voltage transistor including four layers of first side wall film, second side wall film, third side wall film, and fourth side wall film that are formed in such a way that they are laminated in a sequential order from both side surfaces of a gate electrode in directions that are sidewardly remote away from this gate electrode; the side walls of the low voltage transistor including three layers of the first side wall film, the second side wall film, and the fourth side wall film that are formed in such a way that they are laminated in a sequential order from both side surfaces of a gate electrode in directions that are sidewardly remote away from this gate electrode, wherein the first side wall film is made of different material than the second side wall film, and the second side wall film is made of different material than the third side wall film and the fourth side wall film.