| 摘要 |
PURPOSE:To improve cell characteristics when a semiconductor device is used for an EPROM cell by increasing the withstanding voltage of an oxide film formed onto the surface of a polycrystalline silicon film. CONSTITUTION:A foundation oxide film 12 and a polycrystalline silicon film 13 are deposited on the surface of an N-type silicon substrate 11, and phosphorus is diffused for 15min at 950 deg.C in a POCl3 atmosphere, thus bringing phosphorus concentration in the polycrystalline silicon film 13 to 1X10<20>cm<-3>. A PSG film (a phosphorus-doped oxide film) 14 having phosphorus concentration of 1X10<21>cm<-3> is deposited on the whole surface through a CVD method, and annealed for 30min at 950 deg.C in a N2 atmosphere. The PSG film 14 is removed through dipping for 1min in NH4F, and a polycrystalline silicon oxide film 15 is formed onto the surface of the polycrystalline silicon film 13 through dry oxidation. |
