PURPOSE: To enhance the uniformness of thickness and quality of a stacked film on a substrate by a method wherein gas supplying and discharging pipes having plural gas supplying inlets and discharging outlets are installed in the longitudinal direction of the inner surface of a reaction pipe for forming a stacked film, employing a reduced-pressure vapor growth method.

CONSTITUTION: Reaction gas supplying pipe 3 and discharging pipe 4 are installed along the longitudinal inner surface of the silica reaction pipe 1 enclosed by the heating oven 2. Plural reaction gas inlets 5 are installed to the gas supplying pipe 3, while plural outlets 6 to the discharge pipe 4. Substrates 91W9n are placeded in the reaction pipe 1, and SiH2Cl2 and NH3 gas are guided from the inlets 5 to form a stacked film of Si3N4 on the substrates. Because there are plural gas inlets and outlets on the entire inner surface of the reaction pipe 1, the air in the pipe is excluded and the atmopsheric pressure of the reacting gas is controlled, both rapidly and properly. As a result, an Si3N4 stacked film with uniform thickness and quality is easily formed on the plural substrates.