Non-volatile semiconductor memory device

Abstract

A non-volatile semiconductor memory device comprises a semiconductor substrate of a first conduction type, an impurity buried layer of a second conduction type formed at the surface of the semiconductor substrate for constituting either one of a drain region or a source region, an epitaxial layer of a second conduction type formed at the surface of said impurity buried layer, an insulatiang partition wall extended vertically from the surface of the epitaxial layer surrounding operation regions in the impurity buried layer for defining the operation regions therein, at least one electron holding portion extended vertically with a predetermined distance from the operation regions and disposed within the insulating partition wall apart from the operation region, the impurity buried layer or the drain region by an insulation film of such a thickness as causing a tunnel effect, control gates disposed within the insulation partition wall disposed on every electron holding portions on the side opposite to the operation regions and extended vertically with a certain gap from the electron maintaining portions, and a control gate disposed within the insulating partition wall on every electron holding portions on the opposite side to the operation region extended vertically and with a certain gap to the electron holding portions, and an impurity region of a second conduction type formed at the surface of the operation region for constituting the other of the drain region or the source region.