The effect of zirconium dopant on the properties of copper films

Cu-Zr alloy films were sputtered on Si substrate with co-sputtering technology that are composed of magnetron sputtering (MS) and ion beam sputtering (IBS). The Cu films sputtered with magnetron sputtering on the TaN diffusion barrier were used as control experiment. Atomic force microscope, four-point probe method, X-ray diffraction, nano-indentator and Auger electron spectroscopy were employed to characterize the microstructure and properties of the Cu-Zr alloy and Cu films. The results reveal that the surface roughness of Cu-Zr alloy films is obviously different from the one of Cu films. After annealed at 450 °C, the resistivity of Cu-Zr alloy films is slightly higher than that of Cu films, but the hardness of annealed Cu-Zr alloy films is much more higher than that of pure Cu films. After annealed at 800 °C, CuSi₃ phase and TaSi₂ phase appear in Cu/TaN film system, but there is no new phase in Cu-Zr/TaN film system. The reasons are that the Zr atoms diffuse to the interface of Cu-Zr/TaN and come into being a new diffusion barrier between Cu-Zr and TaN, which prevents the diffusion between Cu and Si.