| 摘要 |
PURPOSE:To improve the characteristics and integration of various high frequency devices by e.g. extremely facilitating the processing of gate electrode at low cost by a method wherein a sidewall of the second layer is formed on a step difference while properly adjusting the thickness of the second layer during the process of lamination. CONSTITUTION:A thin silicon dioxide film 13 is formed on a semiconductor substrate 11 exposed to the part beside a step difference part 12A. First, a silicon film 14 is removed from the surface of silicon oxide films 12, 13 by anisotropic overall etching process. Second, the silicon dioxide films 12, 13 on the substrate 11 are selectively removed to leave a sidewall 14A of the silicon nitride film 14 on the removed part exposing the surface of other part. Third, the surface of sidewall 14A of film 14 and the surface of substrate 11 are coated with photoresist (the third layer) in specified thickness. Finally, the sidewall 14A only is selectively removed by dryetching process to expose the surface of silicon dioxide film 13.
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