| 摘要 |
PURPOSE:To form a fine element separating region by forming a sidewall, then selectively oxidizing it, then removing the sidewall, and then selectively oxidizing again it to suitably generate bird's beaks to alleviate a stress and a crystal defect generated at the end of the element separating region. CONSTITUTION:After a silicon nitride film 15 and further an NSG film 16 are deposited, the film 16 is anisotropically etched to form a sidewall 16' of the NSG film, and the film 15 is selectively etched with the sidewall as a mask. A sidewall 15' made of the silicon nitride film is formed by removing the films 14, 16'. A field oxide film 17 is grown by selectively oxidizing it in a steam atmosphere. Only the film 15' is selectively removed, again selectively oxidized to form a final field oxide film 17', and a silicon nitride films 13 and a first thermal oxide film 12 are removed.
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