Patent ID: 8828257

Claim:
An operation method of a plasma processing apparatus including a processing chamber disposed in a vacuum container, the processing chamber having a reduced pressure and having plasma generated therein, a sample stage disposed in a lower part of the processing chamber, the sample stage having an upper surface on which a wafer to be processed by plasma is located, a plurality of pins disposed in through holes in the sample stage so as to enable movement of the plurality of pins in a vertical direction and to enable the plurality of pins to abut against a rear side of the wafer and to move the wafer up and down with respect to the upper surface of the sample stage, and a plurality of openings disposed in the upper surface of the sample stage respectively communicated with the plurality of through holes disposed in the sample stage so that the plurality of pins are respectively movable in the plurality of through holes, the method comprising the step of: feeding gas from supply ports communicating with the inside of the through holes into the processing chamber through the openings in the upper surface of the sample stage while plasma is generated in the processing chamber above the sample stage and upper ends of the plurality of pins are maintained above the upper surface of the sample stage in a state that the wafer is not located on the plurality of pins.