Patent ID: 7541246

Claim:
A method for manufacturing a semiconductor device, comprising: ion-implanting fluorine in a silicon substrate; thermally oxidizing said silicon substrate to form a fluorine-containing silicon oxide film on said silicon substrate; forming a high dielectric constant insulating film on said fluorine-containing silicon oxide film; forming a silicon nitride film on said high dielectric constant insulating film, said fluorine-containing silicon film, said high dielectric constant insulating film, and said silicon nitride film constituting a gate insulating film structure; forming a silicon film on said silicon nitride film; processing said silicon film to form a gate electrode; and heat treating said silicon substrate to diffuse fluorine from said fluorine-containing silicon oxide film and nitrogen from said silicon nitride film into said high dielectric constant insulating film, wherein, in said gate insulating film structure, concentration of fluorine progressively decreases from an interface of said gate insulating film structure with said silicon substrate to an interface of said gate insulating film structure with said gate electrode, and concentration of nitrogen progressively decreases from the interface of said gate insulating film structure with said gate electrode to the interface of said gate insulating film structure with said silicon substrate.