Plasma processing apparatus, and method of maintaining interior of processing container of the plasma processing apparatus

An apparatus for plasma processing that performs an etching on a workpiece, comprising:

• a container;
• a gas supply system configured to supply a processing gas into the container;
• a plasma source configured to excite the processing gas supplied from the gas supply system;
• a support configured to hold the workpiece inside the container;
• an exhaust system configured to exhaust an internal space of the container;
• a plurality of electrode plates provided on an inner wall of the container;
• a plurality of insulators configured to electrically insulate the plurality of electrode plates from each other;
• a DC power supply configured to independently apply a DC voltage to each of the plurality of electrode plates;
• and
• a controller configured to control the gas supply system, the plasma source, and the DC power supply,
• wherein the controller controls the gas supply system, the plasma source, and the DC power supply such that the DC voltage is supplied to each of the plurality of electrode plates during execution of the etching or after completion of the etching.