| 摘要 |
In a vertical thermal treatment apparatus wherein a plurality of semiconductor wafers are held in multiple layers within a wafer boat, the wafer boat is mounted onto a turntable at the upper end of a rotational shaft that penetrates from a bottom portion through a shaft hole into a vertical reaction vessel, and the wafers are subjected to a thermal treatment while the wafer boat is rotated; a seal is formed between the rotational shaft and the penetration portion, to restrain the intrusion of gases and moisture into the seal portions from the interior of the reaction vessel and to eliminate adverse effects on the seal materials. The space within a gap between a shaft hole 33 and a rotational shaft 4 communicates with a space between a fixing member 34 and an outer shell member 44, and a magnetic seal portion 7 is provided between this fixing member 34 and the outer shell member 44. This increases the effective length of the shaft hole 33 from the reaction vessel to the magnetic seal portion 7, preventing the intrusion of gases and moisture into the magnetic seal portion 7 from the reaction vessel during reduced-pressure CVD and also alleviating the effects of heat from the reaction vessel which is heated to a high temperature by a heating furnace 21, thus preventing deterioration of the magnetic fluid.
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