Patent ID: 7556839

Claim:
A method of manufacturing a semiconductor device, comprising the steps of: loading a substrate into a reaction furnace, processing the substrate in the reaction furnace, performing a 1 st purge in a state of the processed substrate in the reaction furnace by evacuating an inside of the reaction furnace through an exhaust line, supplying an inert gas into the reaction furnace, thereby changing a pressure in the reaction furnace, unloading the processed substrate from the reaction furnace, and performing, after the processed substrate is unloaded from the reaction furnace and before another substrate is loaded into the reaction furnace, a 2nd purge by evacuating the inside of the reaction furnace through the exhaust line, supplying the inert gas into the reaction furnace, thereby changing the pressure in the reaction furnace, wherein an amount of change in the pressure in the reaction furnace in the 2 nd purge step is larger than an amount of change in the pressure in the reaction furnace in the 1 st purge step; and in the 1 st purge and in the 2 nd purge, the evacuation of the inside of the reaction furnace and the supply of the inert gas into the reaction furnace are repeated two or more times; and in the 1 st purge, the evacuation of the inside of the reaction furnace and the supply of the inert gas into the reaction furnace are performed under a state that an exhaust valve, which is provided in the exhaust line, is open; and in the 2 nd purge, the evacuation of the inside of the reaction furnace is performed under the state that the exhaust valve is open and the supply of the inert gas into the reaction furnace is performed under a state that the exhaust valve is closed.