Abstract: A method of forming a thin film for a semiconductor device, for forming a metal thin film by chemical vapor deposition on an intermediate layer which is provided on a substrate, comprises the steps of activating the surface of the intermediate layer by introducing a halide gas of a metal for forming the thin film onto the surface of the intermediate layer, forming nuclei on the surface of the intermediate layer by introducing a silane-system gas onto the activated surface of the intermediate layer, and introducing the halide gas and a reducing gas onto the surface of the intermediate layer formed with the nuclei, thereby depositing the metal thin film on the surface of the intermediate layer.

Abstract: A method of and an apparatus for removing a naturally grown oxide film and contaminants on the surface of a semiconductor substrate and then forming a thin film on the cleaned surface. The semiconductor substrate is placed in a pretreatment chamber and then hydrogen chloride gas is introduced into the chamber. Then, the semiconductor substrate is heated at a temperature between 200.degree..about.700.degree. C. and the surface of the semiconductor substrate is irradiated with ultraviolet rays, whereby the naturally grown oxide film and other contaminants on the semiconductor substrate can be removed. Then, a thin film is formed on the cleaned surface of the semiconductor substrate by a CVD method or a sputter method. According to this method, the naturally oxide film and other contaminants can be removed from the surface of the semiconductor substrate at a low temperature and the thin film can be formed on the cleaned surface.