Sputtering of Ta2O5 by Ar+ ions at energies below 1 keV

The sputtering of anodically formed Ta2O5 layers of about 3500 A thickness has been studied by Sputtered Neutral Mass Spectroscopy (SNMS). For perpendicular bombardment with Ar+ ions up to 900 eV the flux of ejected neutral particles is found to consist almost exclusively of metal atoms Ta and Oxide specific molecules TaO and TaO2 with intensity ratios in the order 1 : 1 : 10-1. From depth profiling measurements with SNMS, and from the intensity ratios in the SNMS spectra the total sputtering yield of Ta2O5 and the partial yields of Ta, TaO and of oxygen have been determined for normally incident Ar+ ions of 100 to 600 eV. After an initial increase the TaO intensity in the SNMS spectra remains constant during the sputter removal of the whole layer. A simple model is derived by which the preferred emission of TaO molecules, and the initial increase of the TaO intensity is referred to ion induced variations of the surface stoichiometry of Ta2O5. For optimum TaO production the model predicts equal atomic surface concentrations of Ta and O. (Auth.)