Patent ID: 7883581

Claim:
A substrate processing apparatus comprising: a reaction vessel configured to process a substrate; a heater configured to heat an inside of the reaction vessel; a gas supply line configured to supply gas to the inside of the reaction vessel; a first valve installed at the gas supply line; a flow rate controller installed at the gas supply line for controlling a gas supply flow rate; a main exhaust line configured to exhaust the inside of the reaction vessel; a second valve installed at the main exhaust line; a slow exhaust line installed at the main exhaust line for bypassing the second valve; a third valve installed at the slow exhaust line; a throttle part installed at the slow exhaust line for throttling a gas flow path of the slow exhaust line; a vacuum pump installed at the main exhaust line for evacuating the inside of the reaction vessel; and a controller configured to control the valves and the flow rate controller during a period where the substrate is not processed, so as to exhaust the inside of the reaction vessel through the slow exhaust line using the vacuum pump while supplying inert gas to the inside of the reaction vessel at a flow rate higher than a total flow rate of gas supplied to the inside of the reaction vessel during a substrate processing operation.