Placing bed structure, treating apparatus using the structure, and method for using the apparatus

A holding stage structure which holds a substrate and is disposed in a process chamber, the process chamber being vacuum-evacuatable and allows to perform on the substrate therein a predetermined process which generates water molecules as byproduct, the holding stage structure comprising:

• a holding stage body on which the substrate is placed;
• an elevation pin mechanism lowering the substrate onto the holding stage body or raising the substrate from the holding stage body;
• a stepped portion formed by a projecting portion that is formed by projecting a central portion, other than a peripheral portion, of the holding stage body so that a peripheral portion of a rear surface of the substrate placed on the holding stage body is exposed to a processing gas supplied into the process chamber, and
• a plurality of first groove portions formed in the projecting portion, wherein when spaces are defined between the plurality of first groove portions and the substrate placed on the holding stage body, the spaces penetrates in a plan view the projected central portion to communicate horizontally with an inside space of the process chamber, and
• wherein a first area is an area of the holding stage which is within the stepped portion in a plan view, a second area is an area of the first area other than the first groove portions, and
• a ratio of the second area to the first area and the depth of the spaces are determined to meet a condition that a pressure applied to the substrate due to water vapor is less than the weight of the substrate per unit area, the water vapor being generated from the water molecules, which is attached to the rear surface of the substrate, due to a temperature difference between the substrate and the holding body stage when the substrate contacts the holding body stage in the predetermined process.