MAGNETIC FLUID SEALING UNIT FOR SEMICONDUCTOR WAFER VERTICAL HEAT TREATING APPARATUS

摘要

An outer shell member (60) is fixed to the lower end of a rotational shaft (20) so as to wrap around a unit main body (30) from the lower side thereof to the outer periphery thereof. The gap between the rotational shaft (20) and the unit main body (30) is magnetically sealed by a ferrofluid seal portion (40). A bearing portion (70) is provided at the lower end portion of the unit main body (30) between the unit main body (30) and the outer shell member (60). Purge gas is supplied to the gap between the rotational shaft (20) and the unit main body (30) at a position nearer to the reaction container than the ferrofluid seal portion (40) and in the neighborhood of the ferrofluid seal portion (40) .