Manufacture method of MOS semiconductor device having extension and pocket

A semiconductor device manufacture method comprising the steps of:

• (a) forming an isolation region in a semiconductor substrate, said isolation region defining an active region of a first conductivity type;
• (b) forming a gate insulating film on a surface of said active region;
• (c) forming a gate electrode on said gate insulating film;
• (d) implanting impurity ions of the first conductivity type in said active region by using said gate electrode as a mask, to form pocket regions;
• (e) after said step (d), depositing a first insulating film on said semiconductor substrate, said first insulating film covering side surfaces and an upper surface of said gate electrode;
• (f) implanting impurity ions of a second conductivity type opposite to the first conductivity type in said active region by using said gate electrode and said first insulating film as a mask, to form extension regions;
• (g) forming side spacers on side walls of said first insulating film;
• and
• (h) implanting impurities of the second conductivity type into said active region by using said gate electrode, said fist insulating film, and said side spacers as a mask, to form source/drain regions.