Patent ID: 8975686
Filing Date: 2015-03-10
Classification: H01L

Abstract:
1. A semiconductor device comprising: a semiconductor layer having a surface; a trench extending downward from the surface of the semiconductor layer, the trench having a first side, a second side opposite the first side, and a bottom; a source region formed on a surface layer portion of the semiconductor layer adjacently to the first side of the trench in a prescribed direction; a drain region formed on the surface layer portion of the semiconductor layer adjacently to the second side of the trench in the prescribed direction; a first insulating film formed on the bottom surface and the first and second side surfaces of the trench, the first insulating film having a thin portion and having a thick portion formed by the remainder of the first insulating film, the thick portion having a thickness that is greater than the thickness of the thin portion; a floating gate stacked on the first insulating film and opposed to the bottom surface and the side surfaces of the trench through the first insulating film; a second insulating film formed on the floating gate; and a control gate at least partially embedded in the trench so that the portion embedded in the trench is opposed to the floating gate through the second insulating film, wherein the thick portion of the first insulating film covers the bottom surface of the trench entirely.