Power supply system, plasma processing apparatus, and control method

A power supply system comprising:

• a radio frequency power supply configured to supply radio frequency power to generate plasma in a chamber of a plasma processing apparatus;
• a bias power supply configured to repeatedly supply an electric bias to a substrate support at a time interval of a waveform cycle to attract ions from the plasma to a substrate on the substrate support in the chamber;
• and
• a power supply circuitry,
• wherein the waveform cycle includes a plurality of phase periods, and the plurality of phase periods includes a plurality of designated phase periods of which a total number is less than a total number of the plurality of phase periods, and
• the power supply circuitry is configured to:
• determine respective frequencies of the radio frequency power for the plurality of designated phase periods by adjusting the frequency of the radio frequency power for an m-th designated phase period among the plurality of designated phase periods within an i-th waveform cycle in a sequence of waveform cycles so as to suppress reflection of the radio frequency power, based on a change in the frequency of the radio frequency power for the m-th designated phase period and a change in a degree of reflection of the radio frequency power prior to the i-th waveform cycle in the sequence;
• and
• determine respective frequencies of the radio frequency power for phase periods, other than the plurality of designated phase periods, among the plurality of phase periods within the i-th waveform cycle by interpolation using the respective frequencies of the radio frequency power for the plurality of designated phase periods.

A control method comprising:

• (a) supplying radio frequency power from a radio frequency power supply to generate plasma in a chamber of a plasma processing apparatus;
• and
• (b) repeatedly supplying an electric bias to a substrate support at a time interval of a waveform cycle to attract ions from the plasma to a substrate on the substrate support disposed in the chamber,
• wherein the waveform cycle includes a plurality of phase periods, and the plurality of phase periods includes a plurality of designated phase periods of which a total number is less than a total number of the plurality of phase periods, and
• the (a) includes:
• (c) determining respective frequencies of the radio frequency power for the plurality of designated phase periods by adjusting the frequency of the radio frequency power for an m-th designated phase period among the plurality of designated phase periods within an i-th waveform cycle in a sequence of waveform cycles so as to suppress reflection of the radio frequency power, based on a change in the frequency of the radio frequency power for the m-th designated phase period and a change in a degree of reflection of the radio frequency power prior to the i-th waveform cycle in the sequence;
• and
• (d) determining respective frequencies of the radio frequency power for phase periods, other than the plurality of designated phase periods, among the plurality of phase periods within the i-th waveform cycle by interpolation using the respective frequencies of the radio frequency power for the plurality of designated phase periods.