| 摘要 |
PROBLEM TO BE SOLVED: To facilitate removal of the shield gate oxide film before thermal oxidization where a sidewall oxide film is partially formed in the isolation of the field shielded element in which a sidewall oxide film part is formed through thermal oxidization, and to improve the electrical characteristics of a transistor. SOLUTION: When a field shield element, where the part of side wall oxide film 5 is formed by thermal oxidization, is isolated, a gate oxide film 12 and a shield gate oxide film 2 are formed respectively, in such a manner that they are thinly formed in an element activated region 7 and formed thick on an element isolation region 8. As a result, when a sidewall oxide film is formed, the shield gate oxide film can be removed easily prior to its thermal oxidization by wet washing using fluoric acid. Accordingly, a damaged layer, which is damaged when the shield gate oxide film is removed, will not be introduced. As a result, the production yield and the electrical characteristics of the semiconductor device can be improved.
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