Semiconductor device including a multilayered interelectrode insulating film

Abstract

A semiconductor device includes an element isolation region having an element isolation insulating film therein; an active region delineated by the element isolation region; agate insulating film formed in the active region; a charge storage layer above the gate insulating film; and an interelectrode insulating film. The interelectrode insulating film is formed in a first region above an upper surface of the element isolation insulating film, a second region along a sidewall of the charge storage layer, and a third region above an upper surface of the charge storage layer. The interelectrode insulating film includes a stack of a first silicon oxide film, a first silicon nitride film, a second silicon oxide film, and a second silicon nitride film. A control electrode layer is formed above the interelectrode insulating film. The second silicon oxide film is thinner in the first region than in the third region.