Plasma processing apparatus and sample stage thereof

A plasma processing method comprising the steps of:

• mounting a wafer to be processed on an upper surface of a sample stage which is disposed in a processing chamber inside a vacuum vessel;
• generating a plasma inside the processing chamber;
• and
• adjusting a temperature of the wafer in a predetermined permissible range using at least one of heater units which is disposed inside a dielectric film constituting the upper surface of the sample stage and configured to generate heat,
• wherein the at least one of heater units is comprised of a plurality of arcuate portions which are arranged in a ring-shape so as to surround a central region of the dielectric film and connected in series inside the dielectric film, and the at least one of heater units is supplied DC power from a DC power supply, and
• the step of adjusting the temperature of the wafer includes a step of adjusting amounts of DC current in each of the plurality of arcuate portion of the at least one of heater units supplied from the DC power supply.