Ceramic heater

A ceramic heater for a semiconductor substrate process comprising:

• a mounting plate on which the substrate is mounted;
• and
• a supporter configured to support the mounting plate, wherein
• the mounting plate includes:
• a first base made of a ceramic sintered body and having a mounting surface on which the substrate is mounted, and having a lower surface provided on an opposite side to the mounting surface;
• and
• a second base made of a ceramic sintered body and having an upper surface bonded to the lower surface of the first base, and having a lower surface provided on an opposite side to the upper surface,
• the supporter is made of a ceramic sintered body, is bonded to the lower surface of the second base, and includes a first penetration hole penetrating from one end of the supporter to the other end of the supporter,
• a first region, a first groove and a second region are defined on the mounting surface of the first base,
• the first region has a first surface contacting with the mounted substrate;
• the first groove is provided in a portion covered with the substrate and surrounds the first region;
• and
• the second region has a second surface directly adjacent to and surrounding the first groove,
• the first base has:
• an adsorber configured to adsorb the mounted substrate onto the first surface;
• and
• a plurality of holes each penetrating from a bottom surface of the first groove to the lower surface of the first base,
• at least one of the upper surface of the second base and the lower surface of the first base is provided with a second groove connected to each of the plurality of holes,
• the second base has a second penetration hole connected to the second groove and to the first penetration hole,
• the first groove is supplied with an inert gas through the first penetration hole, the second penetration hole, the second groove, and the plurality of holes,
• the entirety of the second surface of the second region is located lower than the first surface of the first region and higher than a bottom surface of the first groove, and
• wherein a portion of the second surface of the second region is covered with the mounted substrate,
• wherein an annular convex portion surrounds the second surface of the second region, and wherein an inside wall of the convex portion has a tapered surface that surrounds a space formed between the mounted substrate and the second surface of the second region so as to openly enlarge outward from the bottom upward.