NONVOLATILE SEMICONDUCTOR MEMORY DEVICE AND MANUFACTURING METHOD THEREFOR

摘要

PROBLEM TO BE SOLVED: To provide a nonvolatile semiconductor memory device for preventing a deterioration in charge holding characteristic of a cell transistor, by preventing a lower edge (skirt part) of a floating electrode from extending in a tapered shape in the cell transistor. SOLUTION: The nonvolatile semiconductor memory device includes a gate insulating film 302 formed on a semiconductor substrate having a main surface floating gate electrodes (303, 308) formed on the gate insulating film, an ONO insulating film 309 formed on the floating electrode, and control gate electrodes (310, 311). An angel (θ) between a side face of the floating gate electrode on the side of its skirt part and a surface of the gate insulating film under the floating gate electrode is 90 deg. or more.