PURPOSE: To enable control of a speed for forming a metallic film to a specified speed in the stage of sublimating and reducing a solid raw material in a reaction chamber and depositing a high melting metallic film by evaporation on the surface of a wafer by detecting the concn. of the sublimating raw material with an IR absorption cell and maintaining always the specified concn.

CONSTITUTION: A high melting metallic chloride such as MoCl5 is put in a vessel 1 and is heated to sublimate at 100W200°C by a heater 2. He 3 as a carrier gas is at the same time passed through a mass flow controller 4c and a part thereof is supplied via a flow rate controller 4b for control to the inside of the vessel 1. Said gas is passed together with the sublimated gas of MoCl5 through an IR absorption cell 12 and is then supplied into a reaction chamber 5 where the chloride is reduced to Mo by gaseous H2 and the Mo is deposited by evaporation on the surface of th wafer in the reaction chamber. If a change arises in the concn. of the MoCl5 supplied into the chamber 5, the change is detected with an IR spectrophotometer 14 and the output signal therefrom is fed back via a control circuit 15 to the controller 4b which in turn controls the amt. of the He to be introduced into the vessel 1, thereby maintaining the specified concn. of the MoCl5 to be introduced into the chamber 5 and maintaining the specified speed for forming the film deposited by evaporation.