Non-volatile semiconductor memory with outer drain diffusion layer

摘要

A non-volatile semiconductor memory wherein in a semiconductor substrate at both sides of a gate structure, a source diffusion layer and drain diffusion layer having an opposite conductivity type impurity to that of the substrate are provided with a high impurity concentration and a threshold value of a transistor is changed by holding charges in an insulating film in the gate structure, an outer diffusion layer having the same conductivity type impurity as that of the substrate and the impurity concentration higher than that of the substrate intervenes between the drain diffusion layer and the substrate.