Plasma processing apparatus and plasma processing method

A plasma processing apparatus, comprising:

• an inner tube made of aluminum having an anodized surface, the inner tube is provided inside a metal vacuum chamber and in which plasma processing is performed with a substrate disposed in a plasma diffusion region;
• a gas nozzle which is made of aluminum having an anodized surface and which is provided in an inner side wall of the vacuum chamber and disposed to penetrate a through-hole provided in the inner tube;
• a protruding portion having a leading end is provided in the through-hole of the inner tube, the leading end of the protruding portion in point-contact with the gas nozzle is not provided with the anodized aluminum, and
• a surface of a portion of the gas nozzle in point-contact with the protruding portion of the inner tube and in a surface of a portion of the gas nozzle in contact with the vacuum chamber is not provided with the anodized aluminum so that the inner tube is electrically conductive with the vacuum chamber.