Electrostatic chuck, placing table and plasma processing apparatus

An electrostatic chuck comprising:

• a circular placing region configured to place a processing target object thereon,
• wherein the placing region includes:
• a bottom surface;
• and
• a plurality of protrusions protruding from the bottom surface,
• wherein the plurality of protrusions are formed at a plurality of positions on each of a plurality of circles set concentrically and at a first regular interval around a center of the placing region, and
• wherein (i) a first plurality of protrusions among the plurality of protrusions are formed at a first plurality of positions among the plurality of positions along a first circle among the plurality of circles with a second regular circumferential interval, (ii) a second plurality of protrusions among the plurality of protrusions are formed at a second plurality of positions among the plurality of positions along a second circle among the plurality of circles with the second regular circumferential interval, and (iii) a third plurality of protrusions among the plurality of protrusions are formed at a third plurality of positions among the plurality of positions along a third circle among the plurality of circles with the second regular circumferential interval, the second circle being adjacent to the first circle and the third circle being adjacent to the second circle, and
• among the plurality of positions, a plurality of positions set on each of the first, second and third circles are set not to be positioned on a same straight line extending from the center, and
• wherein the plurality of positions of the plurality of protrusions are set at intersection points between the plurality of circles and a plurality of curves extending from the center of the placing region.