Patent ID: 6949788

Claim:
A nonvolatile semiconductor memory device comprising: a substrate; a semiconductor channel forming region in the vicinity of the surface of the substrate; a first and a second impurity regions formed in the vicinity of the surface of the substrate sandwiching the channel forming region between them, acting as a source and a drain in operation; a gate insulating film stacked on the channel forming region, and comprised of a plurality of films; a gate electrode formed on the gate insulating film; a charge storing means which is formed in the gate insulating film dispersed in the plane facing the channel forming region and in the direction of thickness and is injected with excited hot electrons in operation due to an electric field applied; and wherein a bottom insulating film positioned at the bottom in said gate insulating film comprises a dielectric film that makes an energy barrier between the bottom insulating film and the substrate lower than that between silicon dioxide and silicon.