Plasma processing apparatus and gas exhaust method

A plasma processing apparatus comprising:

• a processing chamber in which a sample is to be plasma-processed;
• a radio frequency power supply configured to supply radio frequency power for generating plasma;
• a sample stage on which the sample is to be placed;
• a gas supply mechanism configured to supply a gas to the processing chamber;
• an exhaust device configured to exhaust the gas;
• and
• a control device configured to execute a sequence of exhausting a gas filled from a gas cylinder in stages and ending gas exhaustion based on a pressure on an exhaust side of the exhaust device and a gas pressure of the gas cylinder, wherein
• the gas supply mechanism includes a first valve disposed between the gas cylinder and a gas flow rate control device, a second valve disposed in a pipe for exhausting the gas filled from the gas cylinder without passing through the processing chamber, and a third valve disposed between the gas flow rate control device and the processing chamber,
• the gas filled from the gas cylinder is exhausted by the sequence a predetermined number of times, and
• the predetermined number of times is a number of times obtained based on a ratio of a length of a pipe from the first valve to the third valve with respect to a length of a pipe from the gas cylinder to the first valve.