| 摘要 |
A MONOS nonvatile memory transistor includes a semiconductor substrate, a memory insulator film on the semiconductor substrate composed of a tunnel insulator film, a memory nitride film and a top oxide film, and a memory gate electrode on the memory insulator film. The tunnel insulator film is constituted of a silicon nitrided oxide film containing oxygen and nitrogen and an oxygen-rich silicon nitrided oxide film or a silicon oxide film to make the nitrogen content of the tunnel insulator film in the vicinity of its interface with the semiconductor substrate greater than its nitrogen content in the vicinity of its interface with the memory nitride film. By this, the barrier height of the tunnel insulator film to holes in the semiconductor substrate is lowered without lowering the barrier height thereof to holes captured on the memory nitride film side.
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