| CPC H01J 37/32669 (2013.01) [H01J 37/32183 (2013.01); H01J 37/32513 (2013.01); H01J 37/3266 (2013.01); H01J 2237/334 (2013.01)] | 9 Claims |

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1. A plasma processing apparatus comprising:
a vacuum vessel in which a plasma processing is performed on a sample;
a radio frequency power source configured to supply radio frequency power for generating plasma;
a sample stage on which the sample is placed; and
a plurality of outer peripheral coils configured to form a magnetic field inside the vacuum vessel and disposed outside the vacuum vessel and comprising a first outer coil extending in a horizontal direction and a second outer coil extending in a vertical direction;
a middle coil disposed in the horizontal direction and positioned inwardly from the first outer coil and having a diameter smaller than a diameter of the first outer coil;
a first yoke having a first portion extending in the horizontal direction that covers the first outer coil and an upper side surface of the vacuum vessel, and a second portion extending in the vertical direction that covers the second outer coil; and
a second yoke having three side portions and arranged in a U-shape to cover a top portion and two sides of the middle coil and has an opening below the second middle coil,
wherein the middle coil and the second yoke each have a portion extending in the horizontal direction that are not covered by the first yoke.
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