A tantalum nitride film rich in tantalum atoms is formed, according to the CVD technique, by simultaneously introducing a raw gas consisting of a coordination compound constituted by an elemental tantalum (Ta) having a coordinated ligand represented by the general formula: N=(R, R′) (in the formula, R and R′ may be the same or different and each represents an alkyl group having 1 to 6 carbon atoms) and NH3 gas into a film-forming chamber, reacting the raw gas with the NH3 gas and forming a reduced compound having Ta—NH3 on a substrate; and then introducing a hydrogen atom-containing gas into the chamber to thus form a tantalum nitride film rich in tantalum atoms. The resulting tantalum nitride film has a low resistance, low contents of C and N atoms, and a high compositional ratio: Ta/N, can ensure sufficiently high adherence to Cu film and can thus be useful as a barrier film. Moreover, tantalum particles are implanted in the resulting film according to the sputtering technique to thus further enrich the film with tantalum.