Abstract: A film with small hysteresis and high voltage resistance is obtained by reducing the carbon content in a gate insulating film on a SiC substrate. Specifically, the carbon content in the gate insulating film is set to 1×1020 atoms/cm3 or less. For this, using a plasma processing apparatus, a silicon oxide film is formed on the SiC substrate and then the formed silicon oxide film is reformed by exposure to radicals containing nitrogen atoms. Thus, the gate insulating film excellent in electrical properties is obtained.

Abstract: A film with small hysteresis and high voltage resistance is obtained by reducing the carbon content in a gate insulating film on a SiC substrate. Specifically, the carbon content in the gate insulating film is set to 1×1020 atoms/cm3 or less. For this, using a plasma processing apparatus, a silicon oxide film is formed on the SiC substrate and then the formed silicon oxide film is reformed by exposure to radicals containing nitrogen atoms. Thus, the gate insulating film excellent in electrical properties is obtained.

Abstract: A flip-flop circuit comprises two basic flip-flop circuits, four field effect transistors, and four amplifiers. The two basic flip-flop circuits respectively composed of a first and a second inverter circuits, and an output terminal of the first inverter circuit is connected to an input terminal of the second inverter circuit and an output terminal of the second inverter circuit is connected to the input terminal of the first inverter circuit. The field effect transistors have sources respectively connected to input terminals of the two basic flip-flop circuits, and gates to which clock pulses and inverse clock pulses are applied. The amplifiers respectively composed of an inverter circuit are connected to output terminals of the two basic flip-flop circuits.