Electrostatic chuck

An electrostatic chuck, comprising:

• a ceramic dielectric substrate having a placement surface configured to have a process object placed thereon;
• and
• a base plate supporting the ceramic dielectric substrate,
• the base plate having an upper surface at the ceramic dielectric substrate side, and a lower surface opposite to the upper surface,
• the base plate including a communicating path located between the upper surface and the lower surface, the communicating path being configured to allow a coolant to pass,
• the communicating path having a spiral shape when viewed along a stacking direction of the base plate and the ceramic dielectric substrate, the communicating path including a first flow path part, the first flow path part being a portion of an outermost circumference of the spiral shape and having a pair of side surfaces along a first direction, the first direction being along a flow of the coolant,
• when viewed along the stacking direction of the base plate and the ceramic dielectric substrate, one side surface of the pair of side surfaces including
• a plurality of convex portions that is convex in a second direction, the second direction being perpendicular to the first direction from the other side surface toward the one side surface of the pair of side surfaces, and
• a plurality of concave portions that is convex in an opposite direction of the second direction,
• the plurality of convex portions and the plurality of concave portions being alternately arranged;
• the chuck further comprising:
• a heater unit located inside the ceramic dielectric substrate or between the ceramic dielectric substrate and the base plate,
• the heater unit heating the ceramic dielectric substrate,
• the heater unit including a heater line,
• the heater line having a pair of sides extending along an extension direction of the heater line,
• at least a portion of one of the pair of sides overlapping the first flow path part in the stacking direction.