Electrical resistivity of RuO x thin films prepared by ion beam sputter deposition

Abstract

A compact ion source using a hollow cathode discharge was fabricated and was applied to the ion beam sputter deposition of RuO x thin films. Ar or Ar + O 2 mixture was employed as the working gas and a compressed RuO 2 powder disk was used as the target. Sputter deposition was carried out by varying the acceleration voltage in the range of 1–5 kV. Electron energy loss spectroscopy (EELS) analysis indicated that the RuO 2 was reduced into RuO x through the sputtering process. The electrical resistivity of RuO x films, about 100 nm thick, is higher than the bulk value of RuO 2 (3.5 × 10 -5 Ω · cm) by about two orders of magnitude. This may be attributed to the amorphous structure of the RuO x films and to the incorporation of foreign atoms. The incorporation of Fe from the ion source into the RuO x films was confirmed by EELS analysis. Temperature dependence of the resistivity of RuO x films prepared at different acceleration voltages was also examined.