| 摘要 |
PURPOSE:To improve electrical characteristics of an MISFET by a method wherein a film which has an etching rate different from the etching rate of a gate electrode is patterned by etching with an etching mask to form an impurity introducing mask. CONSTITUTION:In order to form an impurity introducing mask, for instance, a tungsten silicide (WSi2) film 7 is formed by, for instance, CVD over the whole surface of a semiconduotor substrate 1. The film 7 adheres to the top surface and side surface of a gate electrode 5 composed of a polycrystalline silicon film, the surface of a gate insulating film 4 and the surface of a field insulating film 2. Then the surface of the film 7 is oxidized to form a silicon oxide film 8. At that time, on the surface of the film 7 near the gate electrode 5, the silicon oxide film 8 grows thicker than the other part. Then the whole such structure is etched to leave the silicon oxide film 8 on the surface of the film 7 near the gate electrode 5 only. Then, by utilizing the remaining silicon oxide film 8 as a mask for etching, the film 7 exposed from the film 8 is etched by reactive ion etching to form an impurity introducing mask 7.
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