Interface formation between reactively sputtered tungsten nitride (WNx) or titanium nitride (TiNx) metallic films and thermally grown silicon dioxide (SiO2) layers is studied by interrupted growth with on-line Auger electron spectroscopy. For both composite metals, growth proceeds directly without a metal precursor layer. The chemical stability of these WNx/SiO2 and TiNx/SiO2 interfaces is investigated by rapid thermal annealing up to 850 °C. The WNx/SiO2 interface is stable up to 650 °C while TiNx/SiO2 is stable below 850 °C. Metal–oxide–semiconductor capacitors have been fabricated with WNx and TiNx gates and 7.5 nm thick thermal oxide gate dielectrics with interface trap densities, Dit<2×1011cm−2 eV−1. Capacitance–voltage and current–voltage measurements indicate the Fermi level for TiNx lies near midgap in Si, while for WNx it lies closer to the valence band.

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