| 摘要 |
PURPOSE:To decrease birds' beaks, improving electric characteristics and to obtain a minute semiconductor device in simple processes, by using a silicon nitride film, which is etched with mixed gas of SF6 and He, performing selective oxidation, and performing oxidation and etching of the silicon surface before forming a gate oxide film. CONSTITUTION:A silicon substrate 11 undergoes thermal oxidation, and a first silicon oxide film 12 is formed. A silicon nitride film 13 is deposited thereon. Then, with photoresist 14 as a mask, the silicon nitride film 13 undergoes dry etching by using mixed gas of SF6 and He. Then, with the silicon nitride film 13 as a mask, a field oxide film 16 is grown. Thereafter, the silicon nitride film 13 and the first silicon oxide film 12 are removed, and the silicon surface in an active region is exposed. Then, thermal oxidation is performed and second silicon oxide film 10 is formed. The silicon oxide film 10 is removed with aqueous solution of fluoric acid again. Then a gate oxide film 17 is grown. After a gate electrode 18 comprising polycrystalline silicon is patterned, a source and a drain 19 are formed, Thus an MOS transistor is obtained.
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