PURPOSE: To provide a method for forming polysilicon gate electrodes, 0.1μm or below in gate length, that enables simple mass production through ordinary photolithography techniques, not lithography methods based on X-ray, electron beam or ion beam.

CONSTITUTION: A gate oxide film 2 and a polysilicon film 3 to be a gate electrode 20, are formed on a semiconductor substrate 1, and then an oxidation-proof film 4 is formed. The oxidation-proof film 4 is patterned to expose the polysilicon, which is in turn subjected to dry etching to form an inclined sidewall 10. An oxide film 6 is formed to protect the sidewall, and then the oxidation- proof film 4 is removed. The polysilicon is subjected to dry etching to obtain a polysilicon gate electrode.