Tantalum (Ta) metal films (10-70 nm) were deposited on a Si(100) substrate with a 500 nm silicon dioxide (SiO2) interlayer by ion-beam-assisted sputtering. The as-deposited films have been characterized by X-ray diffraction (XRD) and X-ray reflectivity (XRR) techniques. XRD measurements showed the presence of films of the tetragonal phase of tantalum (beta-Ta) oriented along the (001) plane. XRR measurements indicated the presence of graded Ta films, with a thin interface layer between the 500 nm SiOz layer and the Ta films. The thickness and density of this interface layer was estimated to be 1.9 +/- 0.2 nm and 10.5 +/- 0.5 g/cm(3), respectively. X-ray photoelectron spectroscopy (XPS) was used to probe the chemical composition of this interface layer. XPS investigative studies indicated that the interface was likely composed of tantalum silicide (TaSi2) and tantalum silicate (TaSiOx). However, the TaSiOx layer was reduced during Ar ion sputter depth profile analysis. (C) 2004 Elsevier B.V. All rights reserved.