| 摘要 |
PURPOSE:To prevent reduction of punch through voltage and fluctuation of threshold voltage of a semiconductor device by a method wherein patterning is performed on a polycrystalline silicon film being added with an N type impurity to form source and drain regions. CONSTITUTION:After a field oxide film 12 is formed on a P type silicon substrate 11, a gate oxide film 13 is formed. Then the gate polycrystalline silicon film 14 being added with arsenic is accumulated. After then patterning of gate electrode is performed according to the photoetching method, and the polycrystalline silicon film 14 is etched. Then after the gate oxide film 13 is etched to expose the surface of the silicon substrate 11, the polycrystalline silicon film 15 being added with arsenic is accumulated. The polycrystalline silicon film 15 excepting the area necessary for the source and drain regions is removed by etching, etc. when it is oxidized by steam oxidation (1,000 deg.C), arsenic being added in the polycrystalline silicon film 15 is diffused to form N<+> type regions 16, and a thermally oxidized film 17 is formed. |
