Zr films were deposited on Si(100) substrates without a substrate bias voltage and with substrate bias voltages of -50V and -100V using a non-mass separated ion beam deposition system. Secondary ion mass spectrometry and glow discharge mass spectrometry were used to determine the impurity concentrations in a Zr target and Zr films. It was found that the total amount of impurities in the Zr film deposited at the substrate bias voltage of -50V was much lower than that in the Zr film deposited without the substrate bias voltage. It means that applying a negative bias voltage to the substrate can suppress the increase in impurities of Zr films. Furthermore, it was confirmed that dominant impurity elements such as C, N and O have a considerable effect on the purity of Zr films and these impurities can be remarkably reduced by applying the negative substrate bias voltage. (c) 2005 Elsevier B.V. All rights reserved.