Patent ID: 7772636

Claim:
A nonvolatile semiconductor memory device comprising: a plurality of stacked structures, each including: a first dielectric layer formed on a major surface of a semiconductor substrate, a floating gate electrode layer formed on the first dielectric layer, the floating gate electrode layer including first portions positioned at top corner portions of the floating gate electrode layer and a second portion positioned at a top of the floating gate electrode layer, a second dielectric layer obtained by sequentially forming, on the floating gate electrode layer, a lower dielectric film mainly containing silicon and nitrogen, an intermediate dielectric film, and an upper dielectric film mainly containing silicon and nitrogen, and a control gate electrode layer formed on the second dielectric layer; a buried dielectric layer buried among a plurality of the stacked structures and buried up to a top surface of the control gate electrode layer; and a plurality of silicon oxide films, each silicon oxide film having a first member, which is an upper corner portion of one of the silicon oxide films and which is formed between one of the first portions of the floating gate electrode layer and the lower dielectric film and a second member sandwiched between a side wall of the floating gate electrode layer and a side wall of the buried dielectric layer, each silicon oxide film being not provided on the entire second portion of the floating gate electrode layer, the first member of each silicon oxide film being a continuation of the second member of each silicon oxide film.