Plasma processing apparatus and plasma processing method

A plasma processing method comprising:

• providing a tray having at least one substrate housing hole provided so as to penetrate in a thickness direction to house a plurality of substrates, and a substrate support section protruding from a hole wall of the substrate housing hole;
• housing the plurality of the substrates in the substrate housing hole in the tray so that an outer edge section of a lower surface of each of the substrates is put on the substrate support section;
• lowering the tray toward a stage in a chamber so that the tray is supported with a tray support section of the stage while a substrate installation section is inserted from a lower surface side of the tray into the substrate housing hole, thereby installing the lower surfaces of the plurality of the substrates housed in the substrate housing hole, on a substrate installation surface which is an upper end surface of the substrate installation section, and
• generating plasma in the chamber.