Plasma processing apparatus and method of controlling the same

A plasma processing apparatus comprising:

• a radio-frequency power supply;
• a pair of plasma electrodes;
• a matching box located between the pair of plasma electrodes and the radio-frequency power supply and having an impedance matching circuit including a first variable inductor and a second variable inductor;
• and
• a controller,
• wherein the controller has an efficiency map that correlates an inductance of the first variable inductor and an inductance of the second variable inductor with an efficiency of the matching box, and
• wherein the controller is configured to execute:
• performing impedance matching by varying the inductance of the first variable inductor and the inductance of the second variable inductor;
• obtaining the efficiency of the matching box based on the inductance of the first variable inductor and the inductance of the second variable inductor after the impedance matching and the efficiency map, and calculating output power of the radio-frequency power supply based on the obtained efficiency of the matching box and supply power supplied to the plasma electrodes;
• and
• controlling the output power of the radio-frequency power supply based on the calculated output power.