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Abstract text

According to the present invention, a semiconductor device having a field effect transistor is provided. The field effect transistor comprises a gate insulating film 2 formed on a semiconductor layer 1 and a gate electrode 5 formed on the gate insulating film 2. The gate insulating film 2 has a silicon oxide film including a metal element 4 and nitrogen 3, and characteristics of the silicon oxide film are modified by adding the metal element 4 and nitrogen 3. Respective concentration distributions of the metal element 4 and nitrogen 3 in the gate insulating film 2 have maximum values on an interface side between the gate insulating film 2 and the gate electrode 5, and gradually decrease toward the semiconductor layer 1.