Control method and plasma processing apparatus

1. A method of controlling a plasma processing apparatus including a chamber in which a plasma is generated, a substrate holder, a radio frequency power supply configured to supply radio frequency electric power to the substrate holder, a matching device provided between the substrate holder and the radio frequency power supply,

the matching device including

a first variable capacitor connected in parallel with the radio frequency power supply,

a second variable capacitor connected in series with the radio frequency power supply, and

a third variable capacitor for adjusting output impedance to a high harmonic component, the third variable capacitor being connected in parallel with the first variable capacitor and being disposed at a position closer to the substrate holder relative to the first variable capacitor and the second variable capacitor;

the method comprising:

acquiring output impedance of the matching device in a state in which impedance matching is achieved;

obtaining F-parameters indicating electrical characteristics of the chamber;

calculating a degree of high harmonic component generation using the output impedance of the matching device and the F-parameters; and

controlling impedance of the matching device based on the degree of high harmonic component generation; wherein

the controlling includes adjusting capacitance of the third variable capacitor in the matching device.

2. The method according to claim 1 , wherein

the acquiring of the output impedance includes acquiring output impedance of the matching device with respect to a fundamental component and output impedance of the matching device with respect to a high harmonic component; and

the degree of high harmonic component generation is calculated from impedance of the substrate holder calculated by using the F-parameters and the output impedance of the matching device with respect to the high harmonic component, and from plasma impedance with respect to the high harmonic component.

3. The method according to claim 1 , wherein the plasma processing apparatus further includes a low-pass filter provided between the radio frequency power supply and the matching device, to prevent high harmonic components from flowing into the radio frequency power supply.

4. A plasma processing apparatus comprising a controller including a processor and a memory storing a program causing the processor to perform the method according to claim 1 .