Synthesis of ruthenium dioxide thin films by a solution chemistry technique

Smooth, fine-grained RuO2 thin films have been synthesized and deposited onto [100] silicon substrates via a solution chemistry technique. Ruthenium(III) chloride n-hydrate dissolved in ethanol was used as the precursor solution. Thin films from a 0.38M solution were spun at 4000 rpm for 20 s onto the substrates and fired at temperatures between 400 degrees and 800 degrees C. XRD analysis shows that RuO2 forms over this entire temperature range. Using an appropriate firing schedule, the grain growth can be controlled and reproduced to provide for a uniform grain size distribution consisting of equiaxed, submicrometer diameter grains, The electrical resistance of the films has been measured at 300 K using the conventional four-point probe technique. The resistivity values range from 1.8 mu Omega . m for the films with an average grain size of 250 nm to 3.1 mu Omega . m for the films with 30 nm grains. The presence of residual carbon and hydrogen is not believed to have a significant effect on the resistivity.