US Patent 11791134 Impedance adjustment device

An impedance adjustment device includes a variable capacitor unit. A microcomputer changes the capacitance value of the variable capacitor unit by switching on or off PIN diodes included in n capacitor circuits separately. Thus, the impedance on the plasma generator side when viewed from a high frequency power supply is adjusted. When changing the capacitance value of the variable capacitor unit to a target capacitance value, the microcomputer changes the capacitance value to a relay capacitance value different from the target capacitance value. The microcomputer changes the capacitance value to the target capacitance value after the capacitance value is changed to the relay capacitance value.