PLASMA PROCESSING APPARATUS AND PLASMA PROCESSING METHOD

The invention provides a plasma processing apparatus and a plasma processing method. The plasma processing method for processing a membrane structure formed previously on the upper surface of a waferplaced in the processing chamber in a vacuum container and including a membrane to be processed and a base membrane placed thereunder, by using a plasma formed in the processing chamber includes a step of calculating the etching amount of the membrane to be processed at the time of processing an arbitrary wafer, by using the comparison results of the data of an actual pattern and the data of a detection pattern synthesizing the actual pattern of intensity having the wavelength of interference light obtained while processing the membrane structure on an arbitrary wafer as a parameter, and two intensity patterns having the wavelength of the interference light obtained by processing the membrane structure having the membrane to be processed and three or more base membranes of different thickness before processing the