This invention provides a surface treating apparatus which, despite dry treatment in which HF-derived radicals generated in a plasma production chamber are supplied through an introduction hole into a treatment chamber and HF gas molecules are supplied as a treatment gas around the radical introduction hole to suppress excitation energy and thus to enhance selectivity for Si to remove a natural oxide film, can realize surface treatment capable of realizing good surface flatness equivalent to wet washing requiring elevated temperature treatment, and can grow a Si single crystal film on the surface treated substrate. The amount of impurities such as oxygen and carbon is small on the surface of the substrate after the Si single crystal film formation. Hf or the like is sputtered on the Si single crystal film grown surface followed by oxidation and nitriding to form a dielectric insulating film such as an HfO insulating film. A metal electrode film is then formed. These steps are carried out without the exposure of the substrate to the air, impurity adsorption on the interface can be suppressed, and a C-V curve having a small hysteresis can be provided. Accordingly, in MOS-FET, good device properties can be realized.