Thin Ta layers deposited on Si (100) substrates were irradiated with 475 keV Xe+ ions to fluences of (0.5-2) x 1016 ions/cm2 at temperatures between room temperature and 400 °C. By means of Rutherford Backscattering Spectrometry, the interface mixing and tantalum silicide formation were monitored as function of the ion fluence. TaSi2 phase formation was verified using X-ray diffraction. The interface broadening variance was found to depend linearly on the ion fluence and was explained with the help of a compound formation model involving global thermal spikes.