Microwave supply apparatus, plasma processing apparatus, and plasma processing method

A microwave supply apparatus for supplying a microwave for generation of plasma, the apparatus comprising:

• a waveguide including a first end and a second end, and extending between the first end and the second end;
• a circulator including a first port, a second port coupled to the first end, and a third port coupled to the second end, the circulator being configured to propagate the microwave coming from an input end of the microwave supply apparatus, from the first port to the second port, and return the microwave received at the third port, from the first port to a side of the input end;
• and
• a matcher provided between the input end and the first port of the circulator, the matcher being configured to reflect a part of the microwave returned from the first port to the side of the input end, to the first port of the circulator,
• wherein the waveguide includes a rectangular waveguide, the rectangular waveguide including a first wall and a second wall that face each other, and a third wall and a fourth wall that intersect with the first wall and the second wall and face each other,
• wherein a slot hole extending along a propagation direction of the microwave in the waveguide is formed in the first wall, and the slot hole is provided in a region deviated to a side of the third wall,
• wherein the waveguide includes a first ridge portion provided in the waveguide, and
• wherein the first ridge portion has a rectangular parallelepiped shape, is separated from the first wall, faces the slot hole, is in contact with the second wall and the third wall, and is separated from the fourth wall.