| 摘要 |
PURPOSE:To enhance the reliability by a method wherein a silicon nitride film whose thickness is more than twice as thick as that of a silicon oxide film is formed on the silicon oxide film formed on a silicon substrate. CONSTITUTION:A gate insulating film is constituted by a silicon oxide film 2 formed on a silicon film 1 and by a silicon nitride film 4 which has been formed on the silicon oxide film 2 and whose film thickness is more than twice as thick as that of the oxide film 2. By this setup, no defect is produced at the gate insulating film even by evaluating the time dependence of the destruction of the insulating film until many hours elapse; it is possible to enhance the reliability.
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