Patent ID: 7026213

Claim:
A method of fabricating a flash memory device, comprising the steps of: (a) forming a first SiON film on a semiconductor substrate and thermally treating the first SiON film; (b) forming an insulating film on the thermally treated first SiON film; (c) forming a second SiON film on the insulating film and thermally treating the second SiON film; (d) patterning the thermally treated second SiON film, the insulating film and the thermally treated first SiON film to form trenches; (e) forming a third SiON film on the entire surface, thermally treating the third SiON film, and allowing the thermally treated third SiON film to remain on the sides of the trenches; and (f) forming bit lines within the trenches.