Patent ID: 8022467

Claim:
A nonvolatile semiconductor memory device comprising: a semiconductor substrate; a first insulating layer formed on the semiconductor substrate; a plurality of charge storage layers formed on the first insulating layer; a plurality of element isolation insulating films formed between the charge storage layers respectively; a second insulating layer formed on the charge storage layers and the element isolation insulating films, the second insulating layer including a stacked structure of a first silicon nitride film, a first silicon oxide film, an intermediate insulating film having a relative dielectric constant of not less than 7 and a second silicon oxide film; and a control electrode formed on the second insulating layer, wherein the first silicon nitride film has a nitrogen concentration of not less than 21×10 15 atoms/cm 2 ; wherein the charge storage layers have respective lower side surfaces, and each element isolation insulating film includes a high-temperature oxide film formed along the lower side surfaces of the charge storage layers between the charge storage layers and a coating insulating film formed on an inside of the high-temperature oxide film; and wherein the high-temperature oxide film and the coating insulating film have respective upper surfaces, and the first silicon nitride film is formed on the upper surface of the high-temperature oxide film in upper surfaces of the element isolation insulating films and not on the upper surface of the coating insulating film.