Patent ID: 7705393

Claim:
A nonvolatile semiconductor storage device comprising: a semiconductor substrate including a memory cell region and a peripheral circuit region; a first insulating film formed on the semiconductor substrate in the memory cell region; a memory cell transistor formed on the semiconductor substrate in the memory cell region, including a first conductive film formed on the first insulating film, a second insulating film formed on the first conductive film, and a second conductive film formed on the second insulating film, the second conductive film having a first silicide film; a dummy cell transistor formed on the semiconductor substrate in the memory cell region, including a third conductive film formed on the first insulating film, a third insulating film formed on the third conductive film, and a fourth conductive film formed on the third insulating film, the fourth conductive film having a second silicide film and contacting with the third conductive film by penetrating the third insulating film; a fourth insulating film formed on the semiconductor substrate in the peripheral circuit region; a peripheral transistor formed on the semiconductor substrate in the peripheral circuit region and including a fifth conductive film formed on the fourth insulating film, a fifth insulating film formed on the fifth conductive film, and a sixth conductive film formed on the fifth insulating film, the sixth conductive film having a third silicide film and contacting with the fifth conductive film by penetrating the fifth insulating film; a sixth insulating film formed on the semiconductor substrate in the peripheral circuit region; and a dummy peripheral transistor formed on the semiconductor substrate in the peripheral circuit region, including a seventh conductive film formed on the sixth insulating film, a seventh insulating film formed on the seventh conductive film, and an eighth conductive film formed on the seventh insulating film, the eighth conductive film contacting with the seventh conductive film by penetrating the seventh insulating film, wherein a thickness of the fourth insulating film is larger than a thickness of the sixth insulating film.