Plasma processing apparatus and operation method thereof

An operation method of a plasma processing apparatus including a processing chamber disposed in a vacuum container to form plasma in the processing chamber in which pressure is reduced, a sample stage disposed in lower part of inside of the processing chamber and having an upper surface on which a wafer to be processed by plasma is put, a plurality of pins disposed in the sample stage to be moved in vertical direction so that the plurality of pins abut against rear side of the wafer to move the wafer up and down over the upper surface of the sample stage, and a plurality of openings formed in the upper surface of the sample stage so that the plurality of pins are moved in the openings, wherein

• gas is fed from supply ports communicating with the inside of the openings into the processing chamber through the openings at at least one of the following times:
• when the wafer is not put on the upper surface of the sample stage;
• when the openings are exposed to the processing chamber;
• and
• when the wafer is delivered.