Patent ID: 7897455

Claim:
A semiconductor device comprising: a semiconductor substrate containing silicon and including a source region, a drain region, and a channel region between the source region and the drain region; a tunnel insulating film formed on the semiconductor substrate and including a first insulating film having a first dielectric constant and a second insulating film formed on the first insulating film and having a second dielectric constant smaller than the first dielectric constant; a floating gate electrode formed on the tunnel insulating film and formed of a semiconductor film containing silicon; an inter electrode insulating film formed on the floating gate electrode; and a control gate electrode formed on the inter electrode insulating film, an oxinitride film formed on a side surface of the floating gate electrode, the side surface extending to a channel length direction, wherein the second insulating film is formed of an oxide film and is thicker at its ends than in its center in a channel width direction, the inter electrode insulating film contacts the oxinitride film on the side surface of the floating gate electrode, and the oxinitride film has a distribution of a nitrogen concentration, across its thickness, in which the nitrogen concentration is higher near an interface between the oxinitride film and the floating gate electrode.