Variation of composition of sputtered TiN films as a function of target nitridation, thermal anneal, and substrate topography

Abstract

The chemical composition of reactively sputtered TiN was measured with RBS and AES for aspect ratio 2 topography as a function of Ti target nitridation. The bottom of the aspect ratio 2 topography was nitrogen depleted (Ti:N=1.78:1) as compared to the field (Ti:N=1.01:1) for films sputtered with a non-nitrided target at 20 kW and 400 °C. No such depletion effect was observed for TiN films sputtered with a nitrided target. Thermal annealing of the depleted TiN films at 450 °C in N2 restored the composition to near-stoichiometric. SIMBAD simulation with a saturation-dependent nitrogen sticking coefficient was used to understand the nature of the nitrogen depletion.