(Ti,Zr) N films were prepared by dc reactive magnetron sputtering from a Ti-5 atom % Zr alloy target in N-2/Ar gas mixtures and then employed as diffusion barriers between Cu thin films and Si substrates. Material characteristics of the (Ti,Zr)N film were investigated by X-ray photoelectron spectroscopy and cross-sectional transmission electron microscopy (XTEM). The (Ti, Zr) N film microstructure was an assembly of very small columnar crystallites with a rock-salt (NaCl) structure. Metallurgical reactions of Cu/(Ti, Zr)N-0.95/Si, Cu/(Ti,Zr)N-0.76/Si, and Cu/TaN0.71/Si were studied by X-ray diffraction and sheet resistance measurements. The variation percentage of sheet resistance for all Cu/ barrier/Si systems stayed at a constant value after annealing up to 500degreesC for 30 min. However, the sheet resistance increased dramatically after annealing above 750degreesC for Cu/(Ti,Zr)N0.95/Si, and 500degreesC for both Cu/(Ti, Zr)N-0.76/Si and Cu/TaN0.71/Si. For these samples, the interface deteriorated seriously and formation of Cu3Si was observed by XTEM. Our results suggest that the refractory binary metal nitride film, (Ti, Zr)N, can be used as a diffusion barrier for Cu metallization as compared to the well-known TaN film. (C) 2003 The Electrochemical Society.