| 摘要 |
PURPOSE:To obtain easily the sidewall of a gate electrode, by applying a high concentration ion implantation wherein the uniformity and the mass-productivity are excellent, and a thermal oxidation to the means for forming the sidewall. CONSTITUTION:A gate oxide film 2 and a polycrystal silicon layer 3 in which high concentration impurity is introduced are formed on a silicon substrate 1. The side ends of the polycrystal silicon are processed so as to be almost vertical to the surface. By applying the polycrystal silicon to a mask, the gate oxide film 2 in the region, where a diffusion layer for source and drain is formed, is subjected to etching, and nitrogen ion with low acceleration energy is implanted into the silicon substrate from the vertical diraction. A nitrogen implantation layer 6 of high concentration is formed in the vicinity of the upper surface of a silicon electrode and on the source.drain region. When oxidation is performed for one hour in an atmosphere containing oxygen of 100% at a temperature of 1100 deg.C, the sidewall of the polycrystal electrode in which nitrogen is not implanted is oxidized with a normal rate of oxidation, and a thick oxide film is formed. Thereby, the region where nitrogen is implanted turns to a thick oxide film, so that the sidewall 8 of the electrode is formed.
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