Abstract: A nonvolatile semiconductor memory device comprising: a substrate, a pair of source and drain regions; a channel region between the source and drain regions; a pair of first and second insulating layers on the channel region, and a floating-gate or traps between the first and second insulating layer. The band gap of the first insulating layer increases gradually from the substrate to the floating gate or the traps.

Abstract: A semiconductor non-volatile memory device comprising: (a) memory transistor which has: a first source, drain, and channel regions; a first insulation film formed above the first channel region; a floating gate formed above the first insulation film; and a first impurity region which is formed contiguous with the first drain region adjacent to an end of the floating gate, and which has a conductivity type opposite to that of the first drain region; (b) a switching transistor which has: second source, drain, and channel regions, a second insulation film formed above the second channel region, and a gate electrode formed above the second insulation film; (c) wiring means which connects the first impurity region of the memory transistor to the second drain region of the switching transistor.

Abstract: Impurity ions implanted into a semiconductor silicon substrate are not redistributed during a heating of the substrate from the substrate to the film. Such redistribution does not occur due to the direct nitridation of the silicon substrate for forming the silicon nitride film.