Abstract: A substrate holding assembly for horizontally holding a substrate to be treated is provided in a heat treatment chamber of a heat treatment apparatus. The substrate holding assembly has an annular base, and a plurality of fixed support projections provided on the annular base, for holding the underside of the substrate to be treated. A flexible beam portion is fixed to the annular base, or to a vertical support rod, and a flexible support projection is provided on the beam portion, for flexibly supporting a portion of the substrate to be treated which tends to flex downward under its own weight. Flexure caused by the own weight of the substrate to be treated held in the substrate holding assembly is thus corrected by the flexible holding portions. Accordingly, stresses caused in the substrates to be treated can be decreased or removed, and occurrence of slips in the substrate to be treated can be precluded in a high-temperature heat treatment. Accordingly, high yields can be obtained.

Abstract: The vertical heat treatment apparatus according to the present invention in which a substrate holder holding a plurality of substrates-to-be-processed at a vertical interval is mounted on the top of a cap for opening and closing the bottom opening (furnace throat) of a vertical heat treatment furnace through a heat insulation structure for a heat treatment in the uniform heat region in the furnace, the heat insulation structure comprising support rods for supporting the substrate holder, and a plurality of thin heat insulation plates having insertion holes in which the support rods are loosely inserted in, and supported by the support rods, separated from each other by spacers at a prescribed interval in the direction of height of the support rods, whereby the heat insulation structure can have a simple structure and have decreased heat capacities, and throughput can be improved.