Plasma treatment apparatus and plasma treatment method

A surface-wave plasma treatment apparatus comprising:

• a high-frequency power supply that outputs an electromagnetic wave;
• a first rectangular waveguide for electromagnetic wave distribution, which is connected to the high-frequency power supply and filled with air;
• a plurality of second rectangular parallelepiped waveguides for electromagnetic wave radiation, which are arranged in parallel with each other and connected to the first rectangular waveguide for electromagnetic wave distribution in a direction in which the second rectangular parallelepiped waveguides for electromagnetic wave radiation turn an electromagnetic wave transmitted in the first rectangular waveguide for electromagnetic wave distribution at a right angle;
• a plurality of slit-shaped slots formed in each of the plurality of second rectangular parallelepiped waveguides for electromagnetic wave radiation to allow the electromagnetic wave to be radiated, the direction of the largest dimension of the slit-shaped slots of each of the slit-shaped slots being in parallel extending in a longitudinal direction of the second rectangular parallelepiped waveguides;
• a first dielectric component formed in a plate shape to cover the plurality of slots, the first dielectric component having a thickness smaller than ¼ of a wavelength of an electromagnetic wave in the first dielectric component to prevent the electromagnetic wave from propagating in a thickness direction;
• a treatment vessel, the first dielectric component provided between the plurality of slots and the treatment vessel, the treatment vessel provided in such a manner that the electromagnetic wave radiated from the plurality of slots and introduced into the treatment vessel through the first dielectric component generates a surface wave plasma at an area adjacent to or contiguous with an inner surface of the first dielectric component;
• and a second dielectric component provided to completely fill a connection portion between the first rectangular waveguide for electromagnetic wave distribution and each of the second rectangular parallelepiped waveguides for electromagnetic wave radiation to keep the second rectangular parallelepiped waveguides for electromagnetic wave radiation at a vacuum, wherein the treatment vessel includes a vessel main body and a lid, and an air-tightness maintaining member capable of decompressing and bringing an inside of the treatment vessel into a vacuum state or a vicinity of the vacuum state is provided at a connection portion between the vessel main body and the lid.