Electrostatic-chuck heater

A Johnsen-Rahbek electrostatic-chuck heater to be used in a process of forming a conductive film on a wafer, the electrostatic-chuck heater comprising:

• a disc-shaped ceramic base having on one side a wafer-mounting surface on which the wafer is to be mounted, the ceramic base including an electrostatic electrode and a heating resistor;
• a hollow shaft attached to a side of the ceramic base that is opposite the side having the wafer-mounting surface;
• an outermost projection group including a plurality of projections provided in an annular area of the wafer-mounting surface and arranged on a circle that is concentric with the ceramic base, the annular area having an outside diameter smaller than a diameter of the wafer;
• a circular groove provided on an inner side with respect to the outermost projection group;
• a plurality of through-holes extending in a peripheral wall of the hollow shaft from a lower end through to a central part of a circular-groove enclosed area of the wafer-mounting surface that is on an inner side with respect to the circular groove, each through-hole of the plurality of through-holes allowing gas to be supplied from the lower end of the hollow shaft into a below-wafer space enclosed by the wafer-mounting surface, the outermost projection group, and the wafer mounted on the wafer-mounting surface;
• a branch provided with each through-hole of the plurality of through-holes, extending from each of the respective through-holes in a radial direction inside the ceramic base;
• a circular hole provided inside the ceramic base concentrically with the ceramic base, communicating with the other end of the respective branch;
• and
• a vertical hole provided inside the ceramic base, arranged along the peripheral direction, communicating with the circular hole and opening in an outer peripheral part of the circular-groove-enclosed area that is on an inner side adjacent to the circular groove.