PURPOSE: To form a vapor deposition film having desired film characteristics, by holding a substrate to a temp. of 450°C or less in the presence of ionized or activated modifying gas such as hydrogen from a magnetron type gas discharge device.

CONSTITUTION: A vacuum pump is connected to a bell jar 1 forming a vacuum tank through an exhaust passage 3 having a butterfly valve 2. A heater 5 for heating a substrate 4 to be vapor deposited arranged in the bell jar 1 to 450°C or less and a DC power source 6 for applying DC negative bias voltage to the substrate 4 are provided. In addition, an evaporation source 7 is arranged so as to be opposed to the substrate 4 and a magnetron type DC ion gun 18 is provided in the bell jar 1 as a gas discharge device so that the gas discharge port thereof is opposed to the substrate 4. By this constitution, for example, an amorphous silicon membrane having hydrogen mixed therein can be formed.