Heat treatment apparatus

A heat treatment apparatus, comprising:

• a reaction tube configured to process a plurality of substrates and having an inner tube and an outer tube, the inner tube including:
• a flange protruding outwardly from a lower end of the inner tube, and a concave portion formed in a portion of an outer peripheral side surface of the flange and having a curved surface formed in a sidewall of the concave portion;
• a manifold configured to support the outer tube;
• a support ring fixed to the manifold and configured to support the inner tube by mounting the flange of the inner tube on the support ring, the support ring having a stepped portion which includes a horizontal surface on which the flange of the inner tube is mounted and a vertical surface coming into contact with the outer periphery of the flange and positioning the flange in a radial direction;
• and
• a rotatable roller rotatably installed on the support ring by fixing a fixed pin as a rotation axis of the rotatable roller to the support ring such that a portion of the rotatable roller is positioned at a side of the stepped portion of the support ring,
• wherein the flange of the inner tube is mounted on the support ring such that the rotatable roller is centered in a space provided by the concave portion of the flange and in contact with the curved surface formed in the sidewall of the concave portion of the flange.