| 摘要 |
PURPOSE:To reduce bird's beaks by a method wherein part of a poly Si film is directly nitrided to deposit first and second Si nitriding films, then the Si nitriding films are selectively removed and an oxide film is formed using the remained Si nitriding films as masks. CONSTITUTION:A high-temperature treatment is performed in an atmosphere of ammonia to directly nitride parts of a natural oxide film 23 and an oxidizing film 22 and to form a first oxidation-resistant film 24 which is used as an Si nitriding film. Thereafter, an Si nitriding film is formed on the surface of the first oxidation-resistant film 24 to use as a second oxidation-resistant film 25. Then, a resist film having a window corresponded to a field region programming part is formed in the surface of the second oxidation-resistant film 25, the second oxidation-resistant film 25 and the first oxidation-resistant film 24 are selectively removed by performing a reactive ion etching using the resist film as a mask and thereafter, an impurity 26 for inversion prevention is implanted. The resist film is removed and a thermal oxidation is performed to form a field oxide film 27 on an Si substrate 20.
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