Cu thin films as a seed layer were deposited on Si (1 0 0) substrates by applying a negative substrate bias voltage using a non-mass separated ion beam deposition method. Using resistivity measurement, X-ray diffraction analysis, atomic force microscopy, secondary ion mass spectroscopy, and scanning electron microscopy, the Cu films were characterized. The Cu films deposited at the substrate bias voltage of -50 V showed higher purity, strong (1 1 1) preferred orientation, smoother surface and better step coverage in comparison with the Cu films deposited without the substrate bias voltage. The thickness dependence of the resistivity showed clear size effects with decreasing the film thickness. In the case of Cu (100 nm)/Ta (50 nm)/Si structures, the Cu films deposited on Ta/Si substrates by applied the substrate bias voltage maintained a completely (1 1 1) preferred orientation without (2 0 0) texture even after thermal annealing at 450 degreesC for 60 min. (C) 2003 Elsevier Science B.V. All rights reserved.