Microwave plasma processing apparatus and method

A plasma processing method wherein:

• a first substrate to be processed is processed with a plasma in a processing chamber in which a plasma is generated;
• after said first substrate to be processed is processed with the plasma, said first substrate is transferred from the processing chamber, and thereafter the interior of said processing chamber is cleaned with a plasma without placing any further substrate to be processed on a sample stage in the processing chamber, so as to perform plasma cleaning, whereby the cleaning is performed without any substrate on the sample stage in the processing chamber, wherein said sample stage is cleaned during the plasma cleaning within the processing chamber, and wherein during the cleaning an inert gas is blown into a gap, at the sample stage, in which a wafer push-up is provided, to blow away contaminants in the gap;
• then a next substrate to be processed, after said first substrate, is introduced into said processing chamber, after the cleaning has been finished;
• and
• said next substrate to be processed is then processed.