Zr-Si-N diffusion barriers were sputtered by RF reactive magnetron sputtering with different bias voltage. The Cu films were subsequently sputtered onto the Zr-Si-N films without breaking vacuum. Energy dispersive X-ray spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy, Auger electron spectroscopy, transmission electron microscopy, atomic force microscope, and four-point probe method were employed to characterize the microstructure and properties of the Zr-Si-N films. The results reveal that as the bias voltage increases the Zr/Si ratio and the surface roughness increase, but the resistivity of the film decreases. High sputtering bias is in favor of the growth of ZrN grains in Zr-Si-N film. With the decrease of sputtering bias, the microstructure of Zr-Si-N film changes from composite consisting of nano-grain ZrN and amorphous SiN, to one consisting of amorphous phases of both ZrN and SiN,. The Zr-Si-N film can effectively prevent diffusion of Cu to Si wafer even at high temperature of 850 degreesC. (C) 2004 Published by Elsevier B.V.