A semiconductor device includes a silicon substrate and a gate dielectric film
provided on the silicon substrate. The gate dielectric film includes at least a
first oxide film and an oxynitride film formed on the first oxide film. A peak
position of a concentration of nitrogen of the gate dielectric film is located
in a range of 0.5 nm-1.5 nm from a surface thereof, and in a range of 0.3 nm-2.0
nm from an interface thereof with the silicon substrate, and an element concentration
peak of the nitrogen is 71021 or greater.
