Plasma processing apparatus and processing method

An apparatus for plasma processing comprising:

• a first electrode on which a substrate is placed;
• a plasma generation source configured to generate plasma;
• a bias power supply configured to supply a bias power to the first electrode;
• a source power supply configured to supply a source power having a frequency higher than that of the bias power to the plasma generation source;
• and
• a controller configured to control the bias power supply and the source power supply,
• wherein the source power has a first state and a second state,
• the controller performs a control to alternately apply the first state and the second state of the source power in synchronization with a signal synchronized with a high frequency cycle of the bias power, or a phase within one cycle of a reference electrical state that represents any one of a voltage, a current, and an electromagnetic field measured in a power feed system of the bias power, and
• the controller performs a control to turn OFF the source power at least at a negative peak of the phase within one cycle of the reference electrical state.