Patent ID: 7274006

Claim:
A heater comprising: a heating member formed in a plate shape that includes a substrate-heating surface on which a substrate is mounted and a heating member rear surface which is on a side of the heating member opposing the substrate-heating surface, the heating member having a resistance heating element embedded therein; and an auxiliary member provided on the rear surface side of the heating member and having an opposing surface which opposes the heating member rear surface; wherein the opposing surface of the auxiliary member extends outwardly beyond the heating member rear surface; wherein an opposing wall is provided on the opposing surface of the auxiliary member, the opposing wall being disposed in continuity along a side surface of the heating member and protruding in a direction substantially perpendicular to the opposing surface of the auxiliary member; wherein a planar gas path for gas ejected on the substrate-heating surface is formed between the heating member rear surface and the opposing surface of the auxiliary member; and wherein a gas ejection path communicating from the planar gas path toward the substrate-heating surface is formed between the side surface of the heating member and the opposing wall of the auxiliary member.