Patent ID: 6897536

Claim:
A semiconductor device, comprising: a substrate; a gate electrode formed on said substrate; a first diffusion region of a first conductivity type formed in said substrate at a first side of said gate electrode; a second diffusion region of said first conductivity type formed in said substrate at a second side of said gate electrode; and a third diffusion region of a second conductivity type formed in said substrate underneath said second diffusion region in contact with said second diffusion region, said third diffusion region containing an impurity element of said second conductivity type with a concentration level larger than a concentration level of an impurity element of said second conductivity type contained in a region right underneath said gate electrode when comparison is made at the same depth in said substrate, said gate electrode having side wall insulation films at respective sidewall surfaces thereof, said sidewall insulation films extending from a top part of said gate electrode down to a bottom part of said gate electrode at respective sidewall surfaces.