Patent ID: 7157334

Claim:
A method of manufacturing a flash memory device, the method comprising the steps of: forming a tunnel oxide film on a semiconductor substrate and forming a floating gate electrode with a doped polysilicon film on the tunnel oxide film; forming a hemispherical grain (HSG) polysilicon layer having an HSG pattern an the doped polysilicon film; conducting nitrification on the (HSG) polysilicon layer, thereby forming a nitrified HSG polysilicon film; forming an Al 2 O 3 film on the nitrified HSG polysilicon film; and forming a control gate electrode on the Al 2 O 3 film; wherein the Al 2 O 3 film is formed by the sequential steps of; forming an amorphous Al 2 O 3 film on the nitrified HSG polysilicon film; and performing a crystallization on the amorphous Al 2 O 3 film.