Plasma processing device, power supply system, and control method

Abstract

A power supply system of this disclosed plasma processing device includes a high-frequency power supply, a bias power supply, and a power supply control unit. The high-frequency power supply generates high-frequency power for plasma generation. The bias power supply supplies an electrical bias to a substrate support. The power supply control unit periodically modulates the power level of the high-frequency power during the repetition of a modulation cycle including at least two sub-periods. The power supply control unit is configured so as to, on the basis of changes in the degree of reflection of the high-frequency power and changes in the frequency of the high-frequency power in an n-th phase period during the repetition of the preceding modulation cycle, adjust the frequency of the high-frequency power for the n-th phase period in the modulation cycle included in a feedback period subsequent to the start time of each of the at least two sub-periods.