Semiconductor device and method of forming the same

Abstract

A semiconductor device includes a gate electrode on a gate insulating film over a semiconductor substrate, a first sidewall insulating film on a side surface of the gate electrode, and source and drain regions, each including a pocket diffusion layer of a first conductivity type, and first and second diffusion layers of a second conductivity type. The pocket diffusion layer is disposed in the semiconductor substrate. The first diffusion layer of a second conductivity type extends over the pocket diffusion layer. The first diffusion layer faces toward the gate electrode through the first sidewall insulating film. The second diffusion layer over the first diffusion layer is higher in impurity concentration than the first diffusion layer. The second diffusion layer is separated by the first diffusion layer from the pocket diffusion layer, and has a side surface which faces toward the first sidewall insulating film through the first diffusion layer.