Patent ID: 7378706
Filing Date: 2008-05-27
Classification: H01L

Abstract:
1. A semiconductor device, comprising: a semiconductor substrate having a main surface; an insulating film formed on the main surface of said semiconductor substrate; a floating gate electrode formed on the main surface of said semiconductor substrate via said insulating film; and a control gate electrode extending above the floating gate electrode, wherein said insulating film has a first insulating film located at both end portions below said floating gate electrode, and a second insulating film sandwiched between said first insulating films and located in a middle portion below said floating gate electrode, said first insulating film and said second insulating film are formed in separate steps, said first insulating film is thicker than said second insulating film, and at least a portion of a lower surface of said second insulating film is located lower than the surface of said semiconductor substrate, and the lower surface of said second insulating film has a rounded shape.