Patent ID: 8821656

Claim:
A vertical heat treatment apparatus comprising at least: a reaction tube; a heat treatment boat that is arranged in the reaction tube and holds a substrate; a heater configured to heat the substrate; a gas introduction tube configured to introduce an atmospheric gas into the reaction tube; a gas supply tube connected to the gas introduction tube; and a gas port portion that is formed at a flange body provided under the reaction tube and into which the gas introduction tube is inserted, wherein the gas introduction tube is L-shaped, the gas port portion is tube-shaped, the gas introduction tube is connected to the gas supply tube through a joint outside the reaction tube, the joint has at least a metal short tube having a flange portion, the flange portion of the metal short tube is connected to a flange portion provided at the gas port portion through an O-ring, and a horizontal portion of the L-shaped gas introduction tube is inserted into a through hole formed by connecting the metal short tube to the gas port portion and thereby the gas introduction tube is connected to the gas supply tube through the joint, and a material of the flange body including the gas port portion is quartz, a material of the gas introduction tube is quartz, silicon carbide, or silicon, and a material of the reaction tube is silicon carbide.