| 摘要 |
PROBLEM TO BE SOLVED: To provide a placement table structure capable of preventing a placement table from being broken owing to stress by suppressing a difference between temperatures generated at an inner periphery and an outer periphery of the placement table. SOLUTION: A placement table device includes the placement table 26 for placing a workpiece W on its top surface, a heating means 30 composed of a plurality of heater portions each provided for each of a plurality of heating zones sectioned concentrically on the placement table, a leg portion 28 connected to a center portion of the placement table to support the placement table upright, a temperature measuring means 38 provided corresponding to the innermost circumferential heating zone among the plurality of heating zones, and a power supply control unit 42 which brings the innermost peripheral heater portion under feedback control based upon a measured value of the temperature measuring means, and controls electric power supplied to other heater portions at a safe supply electric power ratio to the predetermined innermost peripheral heater portion so as to have a range of temperature differences with which the placement table is not broken owing to a temperature difference between heating zones. COPYRIGHT: (C)2009,JPO&INPIT |
