Patent ID: 7785954

Claim:
A method of manufacturing a non-volatile semiconductor memory device including a semiconductor substrate having a memory cell region and a peripheral circuit region, comprising: forming a first insulating film on the semiconductor substrate in the memory cell region and a second insulating film on the semiconductor substrate in the peripheral circuit region; forming a first conductive film on the first insulating film in the memory cell region and the second insulating film in the peripheral circuit region, the first conductive film having a first non-doped polycrystalline silicon film; forming device isolation regions in the memory cell region and the peripheral circuit region, each of the device isolation regions including an insulator having a lower portion embedded in the semiconductor substrate and an upper portion protruding from an upper surface of the semiconductor substrate, respectively; implanting impurities in the first conductive film of the memory cell region without implanting the impurities in the first conductive film of the peripheral circuit region; forming an inter-gate insulating film on the impurities-doped first conductive film in the memory cell region without forming the inter-gate insulating film on the non-doped first conductive film in the peripheral circuit region; and forming a second conductive film on the inter-gate insulating film in the memory cell region and on the non-doped first conductive film in the peripheral circuit region, wherein the second conductive film has a second non-doped polycrystalline silicon film.