| 摘要 |
PURPOSE: A method for forming a dual gate oxide film is provided to easily control the threshold voltage between a thick gate oxide film and a thin gate oxide film. CONSTITUTION: The method for forming a dual gate oxide film implants ions into a semiconductor substrate(10) around a thin gate formation portion to form a well. A gate oxide film(20) is stacked on the resulting surface under wet atmosphere. A nitride oxide film(25) is stacked on the gate oxide film. A photoresist film is stacked on the resulting surface, through which the portion where a thin gate oxide film(35) will be formed is open. The nitride oxide film and the gate oxide film, which are stacked on the thin gate oxide formation, are etched by means of a cleaning process through the open portion of the photoresist film. After the photoresist film is removed, an oxide film is grown on the resulting surface to form the thin gate oxide film(35).
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