| 摘要 |
PURPOSE:To obtain a semiconductor device whose characteristics are good by a method wherein one part of a substratum oxide film to be used as a field oxide film is formed to be thick in advance so that an active region is made wide and that miniaturization is realized. CONSTITUTION:After a silicon substrate 1 has been thermally oxidized and a substratum oxide film 2 has been formed on the substrate 1, the oxide film 2 is processed to be a prescribed thickness by an anisotropic plasma etching method by using a photolithographic technique by making use of the oxide film 2 as a mask. A nitride film 3 is formed on the oxide film 2; the nitride film 3 is coated with a resist 6. The resist 6 and the nitride film 3 are etched at an identical etching rate; the surface of a thick part of the oxide film 2 is exposed. The remaining resist 6 is removed. The surface of the exposed oxide film 2 is thermally oxidized; a field oxide film 4 is formed. By this setup, a semiconductor device whose characteristics are good can be obtained.
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