Thin films of TaBx interposed between Cu and Si are examined here as diffusion barriers for Cu metallization. In order to investigate the performance of Cu/TaBx/Si contact systems, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), sheet resistance measurement, scanning electron microscopy (SEM), cross-sectional transmission electron microscopy (XTEM). and Auger electron spectroscopy (AES) depth profile were used. Results of this study indicate that the barrier characteristics are significantly affected by the B/Ta ratio. In addition, the failure mechanism for the Cu/TaBx/Si contact systems is also discussed herein. (C) 2003 Elsevier B.V. All rights reserved.