Temperature-dependent ion mixing and diffusion during sputtering of thin films of CrSi2 on silicon

Measurements of sputtering yields and composition profiles have been carried out using backscattering spectrometry for samples of CrSi2 on Si irradiated with 200-ke V Xe ions. When the CrSi2 layer is thinner than the ion range, the sputtering yield ratio ofSi to Cr increases from 3. 5 for room-temperature irradiation to 65 at 290 ·c. For a thick sample, the corresponding increase is from 2.4 to 4.0. only. These changes are explained in terms of a rise in the Si surface concentration at 290 ·c. The driving force for this process seems to be the establishment of stoichiometric CrSi2 compound. Transport ofSi to the surface is by ion mixing in the thin sample and thermal diffusion through the thick layer.