Patent ID: 7592243

Claim:
A method of fabricating a semiconductor device comprising: a first step of forming a gate electrode over a semiconductor substrate while placing a gate insulating film in between; a second step of introducing at least one diffusion-suppressive substance for suppressing diffusion of a conductivity-providing impurity, which will be introduced later, into the surficial portion of said semiconductor substrate on both sides of said gate electrode; a third step of introducing a conductivity-providing impurity into the surficial portion of said semiconductor substrate on both sides of said gate electrode to a depth shallower than that for said diffusion-suppressive substance; a fourth step of forming an insulating film only on the side faces of said gate electrode; a fifth step of introducing an impurity having a conductivity type same as that of conductivity-providing impurity introduced previously in said third step to a depth deeper than that of said diffusion-suppressive substance introduced previously in said second step; and a sixth step of introducing at least one impurity having a conductivity type opposite to that of the conductivity-providing impurity introduced previously in said third step, so as to attain a concentration profile almost equivalent to that of said diffusion-suppressive substance but has a lower concentration as compared therewith at least over a partial range of depth; wherein said first step comes first, and said second through sixth steps follow thereafter in an arbitrary order, wherein said diffusion-suppressive substance, the impurity introduced previously in said third step, the impurity introduced previously in said fifth step and the impurity introduced previously in said sixth step are partially overlapped, and wherein a depth of the bottom portion of the impurity introduced previously in said sixth step is shallower than that of said diffusion-suppressive substance, and is deeper than that of the bottom portion of the impurity introduced previously in the third step.