Plasma processing apparatus and control method

A method of controlling plasma, the method comprising:

• providing a plasma processing apparatus including:
• a processing container having a ceiling plate and a cylindrical wall, the cylindrical wall including an inner wall surface and an outer wall surface;
• a plurality of amplifiers each configured to output microwaves to the processing container;
• a plurality of microwave introducing radiators provided in corresponding to the plurality of amplifiers, respectively, and disposed in a circumferential direction of the ceiling plate of the processing container so as to introduce microwaves from the plurality of amplifiers into the processing container thereby generating plasma in the processing container;
• and
• a plurality of sensors embedded in the cylindrical wall of the processing container corresponding to the plurality of microwave introducing radiators and protruding from the inner wall surface of the cylindrical wall of the processing container toward an inside of the processing container, each of the plurality of sensors being configured to monitor at least one of electron density Ne and electron temperature Te of the plasma generated in the processing container,
• wherein the plurality of microwave introducing radiators are disposed at positions symmetrical with respect to a central axis of the processing container, and
• controlling at least one of a power and a phase of the microwaves introduced from the microwave introducing radiators based on at least one of electron density Ne and electron temperature Te of the plasma monitored by the plurality of sensors.