Patent ID: 8293646

Claim:
A method for manufacturing semiconductor devices comprising the steps of: loading a substrate into a reaction furnace, supplying silane type gas into the reaction furnace and pretreating the substrate to remove by reduction oxidized film on the substrate during a pretreating step, supplying process gas into the reaction furnace and performing a main processing of the pretreated substrate during a main processing step to form a film on the pretreated substrate, and unloading the substrate from the reaction furnace after the main processing step, wherein hydrogen gas is continuously supplied into the reaction furnace at least during vacuum-exhausting an interior of the reaction furnace in the period from the end of the pretreating step to the start of the main processing step, and the temperature inside the reaction furnace is set between 200 C. and 430 C. to remove the oxidized film by the silane type gas during the pretreating step, and the pressure inside the reaction furnace is set between 1 Pa and 10 Pa.