Patent ID: 7182879

Claim:
A plasma processing method comprising: newly introducing a process gas into an evacuated process chamber to generate plasma, the evacuated process chamber having a thin film attached to an inner surface thereof; performing a plasma processing of the thin film to reduce a thickness of the thin film; exhausting the process gas from the evacuated process chamber; introducing again at least a part of the process gas exhausted from the process chamber into the process chamber while processing the thin film; monitoring a rate of change in the thickness of the thin film corresponding to a circulating ratio of the process gas into the process chamber, the circulating ratio being a ratio of a flow rate of the process gas introduced again into the process chamber to a flow rate of an entire introduced gas, the flow rate of the entire introduced gas being a sum of the newly introduced process gas and the exhausted process gas introduced again; and controlling an introduction condition of the process gas into the process chamber so as to adjust the rate of change in the thickness of the thin film to a regulated value, the introduction condition of the process gas being controlled in accordance with changing the circulating ratio, wherein the regulated value is a rate of change in the thickness of the thin film obtained before changing the circulating ratio.