Patent ID: 7696084

Claim:
A method of producing a semiconductor device, comprising the steps of: preparing a semiconductor substrate; defining a first area and a second area on the semiconductor substrate; laminating sequentially an insulation film and a conductive film in the first area and the second area on one of main surfaces of the semiconductor substrate; patterning the conductive film to form a first gate electrode in the first area and a second gate electrode in the second area; depositing a non-doped silicate glass over the semiconductor substrate for covering the first gate electrode and the second gate electrode; removing the non-doped silicate glass on the first gate electrode; forming a silicon thermal oxide film for covering the first gate electrode in the first area and the non-doped silicate glass in the second area on the semiconductor substrate through thermal oxidation; forming a laminated film for sidewalls including a film for charge accumulation on the silicon thermal oxide film; etching the laminated film for sidewalls, the silicon thermal oxide film in the first area, and the silicon thermal oxide film and the non-doped silicate glass in the second area in a direction perpendicular to the main surface of the semiconductor substrate to form a first sidewall portion on a sidewall of the first gate electrode and a second sidewall portion on a sidewall of the second gate electrode; and introducing impurity ions at a high concentration with the first gate electrode, the first sidewall portion, the second gate electrode, and the second sidewall portion as a mask to form an impurity diffused area.