Non-volatile semiconductor memory device and method of manufacturing the same

Abstract

The charge retention characteristics of a non-volatile memory, particularly, a MONOS-type non-volatile memory is improved. In a non-volatile memory cell including a tunnel silicon oxide film (), a silicon nitride film () serving as a charge storage film, a silicon oxide film (), and a gate electrode () which are sequentially formed on a semiconductor substrate, the tunnel silicon oxide film () has a stacked structure of a silicon oxynitride film () and a silicon oxide film (). Herein, it is configured such that a density of nitrogen atoms contained in the silicon oxynitride film () decreases as a distance from an interface with the semiconductor substrate increases in a film-thickness direction of the silicon oxynitride film ().