Thermal stability of RuO2/Ru bilayer thin film in oxygen atmosphere

The thermal stability of RuO2/Ru bilayer prepared by r.f. magnetron (reactive) sputtering was investigated in an oxygen atmosphere (1 atm). Diffusion barrier property and electrical conductivity were maintained up to 750 degrees C for 10 min without the oxidation of the Ru layer, but the volatilization of RuO2 took place both at the surface and within the film layer. The oxidation of the Ru layer, which is a thermally activated and diffusion-limited process, started with the formation of RuO2 protrusions on the surface of bilayer at 800 degrees C. This could be possible at the initial stage of the Ru oxidation process because of the metal (Ru) diffusion in rutile structure which is faster than oxygen diffusion. (C) 2000 Elsevier Science S.A. All rights reserved.