Plasma processing apparatus and plasma processing method

A plasma processing apparatus, comprising:

• a processing chamber which is arranged inside a vacuum container, and in which plasma is formed;
• a sample table that is arranged in the processing chamber and has an upper surface on which a wafer to be processed is placed;
• a metal base member that is arranged on the sample table and incudes, therein, a refrigerant flow path through which a temperature-adjusted refrigerant flows;
• at least one temperature sensor that is arranged between the refrigerant flow path and an upper surface of the base member and is configured to detect a temperature;
• and a controller that is configured to detect a temperature of the base member or the wafer being processed, which is placed on the sample table, by using an output from the temperature sensor, wherein
• the controller is configured to detect the temperature of the base member or the wafer based on one of a plurality of relations indicating linear functions obtained from results of measurements taken in advance of the processing of the wafer between a plurality of errors and a corresponding plurality of set temperatures of the refrigerant each defining a difference between a temperature obtained from the output of the temperature sensor and an actual temperature of the base member or the wafer as an error, and
• the linear functions are different corresponding to regions of a plurality of continuous temperature ranges within an adjustable temperature range of the refrigerant, and the plurality of linear functions include the same coefficient and have a point where the error is 0.