Efficiency of Zr-Si diffusion barriers in Cu metallization has been investigated. Amorphous Zr-Si diffusion barriers were deposited on the Si substrates by reactive magnetron sputtering with different negative substrate bias. The mass density of Zr-Si films increases with substrate bias voltage up to -150 V. The deposition rate decreased with the negative substrate bias from 5.4 nm/min to 1.8 nm/min. XRD measurements show that the Zr-Si barriers have amorphous structure in the as-deposited state. The FE-SEM images show that the sizes of spherical granules on the Zr-Si film surface increase with increasing the substrate bias. The Cu/Zr-Si/Si structures were prepared and annealed in Ar ambient at temperatures varying from 500 to 650 degrees C for an hour. It is shown from the comparison study that the Zr-Si film deposited with -150 V is better at maintaining good performance in Cu/Zr-Si/Si contact system than that of Zr-Si film deposited with -50 V. (C) 2009 Published by Elsevier B.V