A semiconductor device, which suppresses formation of an organic impurity layer and has excellent adhesiveness to a copper film and a metal to be a base, is manufactured. A substrate (wafer W) coated with a barrier metal layer (base film) 13 formed of a metal having a high oxidation tendency, such as titanium, is placed in a processing chamber. At the time of starting to supply water vapor or after that, a material gas containing an organic compound of copper (for instance, Cu(hfac)TMVS) is supplied, and a copper film is formed on the surface of the barrier metal layer 13 whereupon the oxide layer 13a is formed by the water vapor. Then, heat treatment is performed on the wafer W, and the oxide layer 13a is converted into an alloy layer 13b of a metal and copper which constitute the barrier metal layer 13.