The electrical properties of resistive and dielectric thin films prepared by reactive sputtering from a tantalum-titanium composite target

Abstract

Resistive thin films of TaTiN and dielectric thin films of TaTiO prepared by reactive co-sputtering in ArN 2 or ArO 2 mixtures from a TaTi composite target were investigated in an effort to extend the data on the electrical properties of films prepared by reactive sputtering from tantalum targets. The composition of the thin films was controlled by changing the ratio of the tantalum area to the titanium area on the composite target surface. For the TaTiN films the resistivity, the temperature coefficient of resistance and the Hall coefficient were investigated as functions of the nitrogen partial pressure and the composition of the films. The dielectric constant, the temperature coefficient of capacitance and tan δ were studied as functions of composition in films of the TaTiO system. The resistivities of TaTiN films sputtered at a nitrogen partial pressure of 4 × 10 −4 Torr varied linearly from 50 to 270 μω cm as the tantalum weight percentage of the films increased from 10 to 90%. The temperature coefficient of resistance for these films decreased, again linearly, from 1000 to −50 ppm °C −1 over the same range of tantalum weight percentage. As the titanium weight percentage of the films increased from 10 to 90%, the dielectric constant and tan δ for the TaTiO films varied linearly from 30 to 70 and from 0.008 to 0.025 respectively. It is believed that these resistive and dielectric thin films will be valuable for producing thin film passive elements in hybrid integrated circuits.