Patent ID: 7425480

Claim:
A method of manufacturing a semiconductor device comprising; forming a tunnel insulating film containing silicon and nitrogen on a semiconductor substrate; forming a first film on the tunnel insulating film, the first film to be processed into a floating gate electrode and containing silicon; forming an insulating film on the first film; forming a second film on the insulating film, the second film to be processed into a control gate electrode; processing the second film, the insulating film and the first film to cause a portion of the tunnel insulating film to be exposed to the outside so that the floating gate electrode and the control gate electrode are formed; changing a lower edge of the floating gate electrode into a rounded shape by applying a post oxidation to a semiconductor structure resulting from the above recited formings and processing, the post oxidation using an oxidizing gas containing one of ozone and oxygen radicals, the oxygen radicals being generated by a remote plasma oxidizing method or by reacting a first gas containing oxygen and a second gas containing hydrogen, and a concentration of nitrogen on the part of the tunnel insulating film under an edge portion of the floating gate electrode being decreased by the post oxidation.