PURPOSE: To form a uniform amorphous film on a substrate to be subjected to vacuum deposition, by confining helium or hydrogen in a gap between a temp.- controllable metallic tank and the substrate prior to vacuum deposition so as to keep the temp. of the substrate uniform.

CONSTITUTION: An apparatus composed of a temp.-controllable and rotatable metallic tank 2, a substrate 7 to be subjected to vacuum deposition, and a substrate clamping flange 12 for holding a vacuum state is prepared. Grooves 15, 16 coinciding with the substrate 7 are cut in the flange 12 and a part of the tank 2 opposite to the flange 12, and vacuum gaskets 11 are put in the grooves 15, 16. Prior to vacuum deposition, hydrogen or helium is confined in the gap 10 between the tank 2 and the substrate 7. The temp. of the substrate 7 is kept uniform by utilizing this high heat conductive gas, so an amorphous film of stable quality is obtd.