Semiconductor device and method of producing the same including a charge accumulation layer with differing charge trap surface density

Abstract

There is provided a trap memory device suppresses electric charges from flowing from the outside into a charge accumulation region and accumulated electric charges from diffusing to the outside or flowing out due to a defect. A gate conductoris formed through a laminate insulating film including a first gate insulating film, a charge accumulation layerand a second gate insulating filmon a silicon substrate. The laminate insulating film (to) projects outside the gate conductorand extends to under the outer end of a side wall. The charge accumulation layerincludes a high trap surface-density regionimmediately under the gate conductor and a low trap surface-density regionoutside the gate conductor.