| 摘要 |
After the formation of element isolation insulating films, an n-well, and a p-well on a Si substrate, the Si substrate is subjected to cleaning (step S 1 ) as pretreatment. The surface of the Si substrate is thermally oxidized by rapid thermal oxidation (RTO) to form a silicon oxide film (step S 2 ) as an underlying oxide film. The silicon oxide film is subjected to plasma nitridation (step S 3 ). The plasma nitridation results in the nitridation of the silicon oxide film by the introduction of active nitrogen to form a silicon oxynitride film. Annealing is performed in an ammonia atmosphere (step S 4 ) to further introduce nitrogen into a region near the surface of the silicon oxynitride film. Annealing as post-annealing (step S 5 ) is performed in an atmosphere containing nitrogen and oxygen.
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