PURPOSE: To obtain the formed film product which causes no clouding of α-Si formed film product and which is high in quality are reliability.

CONSTITUTION: The gas for amorphous silicon film-formation is introduced into the inside of the reactor provided with the substrate to be film-formed, and also plasma is generated in the inside of the reactor to form an amorphous silicon film on the substrate, and the gas for etching containing fluorine is introduced into the inside of the reactor after taking out the film-formed substrate from the inside of the reactor to carry out cleaning, then the next substrate to be film-formed is provided in the inside of the reactor under atmospheric pressure, and the pressure in the inside of the reactor is reduced down to 500 Torr in ≥5min. Then, the pressure is reduced down to 1 Torr in ≥5min, and after that, the gas for amorphous silicon film formation is introduced, and also, the plasma is generated in the inside of the reactor to form the next amorphous silicon film on the substrate.