| 摘要 |
PURPOSE:To provide a gate electrode with accurate shape and dimensions and obtain an FET with excellent characteristics by performing anisotropic etching of impurity-doped polycrystalline Si with an etching rate of less than 1000 Angstrom /minute. CONSTITUTION:An aperture is formed in an SiO2 layer 22 and a gate oxide film 23 is formed on a P<->type Si layer 21. A polycrystalline Si layer is built up and, after POCl2 is deposited, oxidized lightly in an O2 atmosphere at 1000 deg.C to improve the adhesiveness to resist and a resist mask is applied and a P-doped polycrystalline Si layer 27 is formed. Then anisotropic etching of the P-doped polycrystalline Si layer 27 which is to be a gate electrode is performed with an etching rate of less than 1000 Angstrom /minute by a CDE method while O2 is made to flow. With this method, the shape and dimensions of the P-doped polycrystalline Si electrode can be satisfactory. Subsequently, a MOS-FET can be completed with the excellent yield and characteristics.
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