| 摘要 |
To improve a charge retention characteristic of a nonvolatile memory transistor. A first insulating film, a charge trapping film, and a second insulating film are formed between a semiconductor substrate and a conductive film. The charge trapping film is formed of a silicon nitride film including an upper region having a low concentration of hydrogen and a lower region having a high concentration of hydrogen. Such a silicon nitride film is formed in such a manner that a silicon nitride film including 15 atomic % or more hydrogen is formed by a chemical vapor deposition method and an upper portion of the silicon nitride film is nitrided. The nitridation treatment is performed by nitriding the silicon nitride film by nitrogen radicals produced in plasma of a nitrogen gas.
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