| 摘要 |
PURPOSE:To obtain good writing (program) characteristics by performing a channel doping after forming a second gate oxide film between the floating gate and the control gate, and implanting an impurity for imparting electrical conductivity. CONSTITUTION:On a first gate oxide film 4, a polycrystalline silicon pattern 106 having end portions overlapping a field insulating film 3 is formed, and after forming a gate oxide film 7 on the upper surface and end faces of the polycrystalline silicon pattern 106 by thermal oxidation, a channel doping by ion implantation is applied to a device forming region through the polycrystalline silicon pattern 106 having the second gate oxide film and the first gate oxide film 4, and an ion implantation of an impurity for imparting electrical conductivity to the polycrystalline silicon pattern 106 is performed through the second gate oxide film 7. With this, control of the impurity profile in the channel forming region by the channel doping is enabled, and the dielectric strength between the floating gate and the control gate can greatly be improved, so the program characteristics will improve.
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