| 摘要 |
PROBLEM TO BE SOLVED: To prevent a thick gate oxide film from being damaged by a washing and hydrofluoric acid pretreatment process that is made before forming a thin gate oxide film. SOLUTION: A first thick gate oxide film is formed, and an insulation film with etching resistance for washing, hydrofluoric acid treatment that is made for forming a second thin gate oxide film is formed on the surface of the first gate oxide film. A resist is formed at a part where the thick gate insulation film is formed, and the first gate oxide film is etched with the resist as a mask. The resist is released, and a surface at a part where the thin gate insulation film is formed is subjected to washing, hydrofluoric acid treatment, thus forming a second thin gate oxide film.
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