Substrate processing apparatus, quartz reaction tube and method of manufacturing semiconductor device

A substrate processing apparatus comprising:

• a reaction tube comprising an outer tube with a closed end and an inner tube provided inside the outer tube, wherein the inner tube is configured to accommodate therein a substrate to be processed;
• a manifold of a cylindrical shape connected to an open end of the reaction tube;
• a lid configured to close one end of the manifold opposite to other end of the manifold connected to the reaction tube;
• a first gas supply pipe configured to supply a cleaning gas inside the reaction tube;
• and
• a second gas supply pipe configured to supply a purge gas for purging a space inside the manifold,
• wherein the reaction tube further comprises:
• an exhaust space formed between the outer tube and the inner tube into a C-shape in horizontal cross-section, wherein two partition plates are installed respectively at two ends of the C-shape to close the two ends of the C-shape in a manner that the exhaust space is surrounded by the outer tube, the inner tube and the two partition plates without any other partition plate installed in the exhaust space;
• an exhaust outlet formed on the outer tube and communicating with the exhaust space;
• a first exhaust port provided in the inner tube so as to face the substrate and configured to discharge a process gas into the exhaust space;
• and
• a plurality of second exhaust ports formed at a bottom of the exhaust space of the C-shape, through which the exhaust space and the space inside the manifold communicate with each other,
• wherein at least one of the plurality of the second exhaust ports is configured to promote an exhaust of a stagnated gas in the exhaust space distanced away from the first exhaust port, and
• wherein the exhaust space is directly in fluid communication with both the exhaust outlet and the first exhaust port.