A method for forming a film of refractory metal used for interconnection in a semiconductor integrated circuit and, above all, to a method for forming a tungsten film (Blk-W film) by a blanket CVD method. A blanket tungsten (Blk-W) film 10 is formed with good adherence and coverage on an SiO.sub.X based interlayer insulating film 3 having a minute-sized contact hole 4 for improving reliability in an interconnection. Before proceeding to Blk-W-CVD, a substrate having a Ti-based adherent layer 7 on its uppermost surface is heated and exposed to a silane-based gas atmosphere for forming Si-nuclei on its surface. A W-nucleus 9 is formed by reducing the WF.sub.6 gas with H.sub.2 and a Blk-W film 10 is also formed by reducing the WF.sub.6 with SiH.sub.4 under a rate determined by the rate of the surface reaction. If the substrate is preliminarily heated before forming the Si nuclei, formation of the Si nuclei proceeds with improved uniformity. The W-nuclei may be carried out uniformly in a temperature range of 450.degree. C. or higher. If the substrate heating temperature during high speed growth is lowered to a temperature lower than that during W-nucleus formation, the thermal stress in the substrate may be released for further improving adherence between the Blk-W film 10 and the substrate.