Patent attributes
A semiconductor device includes a semiconductor layer having a trench; a source region formed in a surface layer portion thereof adjacently to a first side of the trench; a drain region formed in the surface layer portion adjacently to a second side of the trench; a first insulating film formed in the trench; a floating gate stacked on the first insulating film and opposed to the trench, and extending over and covering only partially the source and drain regions; a second insulating film formed on the floating gate; and a control gate at least partially embedded in the trench so that a portion embedded in the trench is opposed to the floating gate through the second insulating film. The first insulating film has a thin portion in contact with the drain region and a thick portion formed by the remainder thereof which covers the entire bottom surface of the trench.
