PURPOSE: To prepare the titled film having improved bond strength to a base plate at high growth rate inexpensively, by heating and vaporizing silicon in a vacuum vessel, feeding hydrogen or fluorine simultaneously in ionic state.

CONSTITUTION: The interior of the vacuum vessel 1 is made in reduced pressure by an exhaust pump connected to the exhaust gas vent 10, and the base plate 3 attached to stand 2 is heated by the heater 5. The evaporation source of silicon 4 is heated by electric resistance heating or electron rays and silicon is vaporized, a silicon film is deposited on the base plate 3 and the injector 9 for hydrogen or fluorine ion is simultaneously started. The interior of the vessel 1 is made in an ionized atmosphere and hydrogen or fluorine ion is injected into the deposited film. The vaporized silicon particles are ionized by keeping the base plate 3 negative based on the evaporation source 4 by the electric source 6 to give a noncrystalline silicon film having higher bond strength to the base plate. A noncrystalline silicon film having higher bond strength is obtained by furnishing the auxiliary electrode 7 with a direct or alternating current potential between the evaporation source 4 and the base plate 3.