Method of manufacturing a semiconductor device with wider sidewall spacer for a high voltage MISFET

A manufacturing method of a semiconductor device, comprising the steps of:

• (a) providing a semiconductor substrate;
• (b) forming a first gate electrode via a first gate insulating film and a second gate electrode via a second gate insulating film over the semiconductor substrate;
• (c) forming a first insulating film over the semiconductor substrate to cover the first gate electrode and the second gate electrode, the first insulating film having first portions on upper surfaces of the first and second gate electrodes and second portions on side surfaces of the first and second gate electrodes;
• (d) forming a first sidewall insulating film selectively formed on the second portions at the side surfaces of the second gate electrode;
• (e) forming a second insulating film over the first insulating film and the first sidewall insulating film;
• and
• (f) after the step (e), etching back the second insulating film, the first sidewall insulating film and the first insulating film to thereby form a second sidewall insulating film having a first width comprising the first insulating film, over the side surface of the first gate electrode and a third sidewall insulating film having a second width comprising the first insulating film, over the side surface of the second gate electrode,
• wherein the first width is smaller than the second width.