| 摘要 |
PURPOSE:To prevent generation of short-circuit and breakdown between a control gate and an erase gate through a double-layer structure by forming a polycrystalline silicon film, which is previously doped with phosphorus in a high concentration, to a polycrystalline silicon film forming an erase gate. CONSTITUTION:A polycrystalline silicon film 206a is formed in the double-layer structure by previously doping phosphorus in the high concentration into a polycrystalline silicon film 206 without implanting arsenic ions thereto. At the time of etching, the edge part of an erase gate is given the smooth inclination. Therefore, the surface of erase gates 207 and 207a formed by etching the polycrystalline silicon films 206 and 206a are smooth without providing the protruded and recessed areas and an insulating film 209 formed on this surface will never be damaged. In the same manner, a protrusion is not formed at the edge portion of the erase gates 207 and 207a and the fear of giving a damage on the insulating film 209 of this area can also be eliminated. In addition, damage on the area where the erase gates 207 and 207a of the insulating film 205 and the floating gate 204 are overlapped can also be prevented. |
