| 摘要 |
After a first gate oxide film ( 302 ) is formed on a substrate ( 301 ), a nitride layer ( 303 ) is formed by a first oxynitriding process. The first gate oxide film is selectively removed from a thinner film part area of the substrate. A second gate oxide film forming process forms a second gate oxide film ( 305 A) in the thinner film part area and a third gate oxide film ( 305 B) in a thicker film part area. By executing second oxynitriding process, nitride layers ( 306 A and 306 B) are formed at the thinner and the thicker part areas.
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