Heat treatment apparatus and heat treatment method

A heat treatment apparatus, comprising:

• a processing container configured to accommodate a plurality of substrates held by a substrate holder in a shelf shape;
• a gas supply source configured to supply a raw material gas into the processing container from a lower position of the processing container;
• an exhaust unit including a pump configured to exhaust the raw material gas in the processing container;
• and
• a heater arranged to cover the processing container and configured to heat the plurality of substrates;
• wherein the gas supply source includes a gas supply pipe including:
• a first straight pipe portion that extends upward along a longitudinal direction of an inner wall surface of the processing container;
• a bent portion where a distal end side extending above the first straight pipe portion is bent downward;
• a second straight pipe portion that extends downward from the bent portion;
• and
• a plurality of gas ejecting holes formed in the second straight pipe portion;
• and
• wherein the first straight pipe portion has a larger cross-sectional area than that of the second straight pipe portion.