Patent ID: 7414292

Claim:
A semiconductor device comprising: a semiconductor substrate; a first active region of a first conductivity type formed in said semiconductor substrate; a second active region of a second conductivity type formed in said semiconductor substrate; a first gate insulating film having a first thickness, and formed on said first active region; a second gate insulating film having a second thickness thinner than the first thickness, and formed on said second active region; first and second gate electrodes formed on the first and second gate insulating films, respectively; side wall spacers of insulating material formed on side walls of said first and second gate electrodes; a first diffusion region of the second conductivity type formed in said first active region outside and aligned with the edge of said side wall spacers; a second diffusion region of the first conductivity type formed in said second active region outside and aligned with the edge of said side wall spacers; a third diffusion region of the second conductivity type having an impurity concentration lower than that of said first diffusion region, and formed in said first active region outside and aligned with the edge of said first gate electrode; a fourth diffusion region of the second conductivity type formed in said second active region outside and aligned with the edge of said second gate electrode, and having an impurity concentration higher than that of said second active region; and a fifth diffusion region of the first conductivity type formed in said second active region and within said fourth diffusion region outside and aligned with the edge of said second gate electrode, and having an impurity concentration lower than that of said second diffusion region; wherein said gate insulating films extend under said side wall spacers and do not extend outside the sidewall spacers, and the impurity concentration distributions of said third diffusion region is substantially equal to that of said fourth diffusion region.