REACTIVE-SPUTTER DEPOSITION AND STRUCTURE OF RUO2 FILMS ON SAPPHIRE AND STRONTIUM-TITANATE

Metallic films of RuO2 were deposited by reactive-sputtering depositio n on single crystal substrates of Al2O3 (0001) and SrTiO3 (100) at roo m temperature and 450 degrees C. Measurement of the characteristic hys teresis loop revealed that the target's transition from a metal to a m etal oxide surface occurred at a very high O-2/Ar ratio (88%) under ou r experimental conditions. The hysteretical behavior of the transition was evaluated experimentally and was modeled. Resonance-enhanced Ruth erford backscattering spectrometry established that the films deposite d at 450 degrees C had an oxygen to ruthenium ratio of 1.97, while a s lightly higher value of 2.08 was observed for the films grown at room temperature. The latter films were amorphous, whereas those grown at 4 50 degrees C exhibited a highly oriented polycrystalline microstructur e. On SrTiO3 (100), the RuO2 (100) plane is parallel to the substrate surface, but no in-plane orientation was found. The same face, RuO2 (1 00), was also parallel to the surface of Al2O3 (0001), and the [001] d irection of individual grains of RuO2 aligned with the three (<(1)over bar 010>) directions of the substrate to produce a threefold mosaic m icrostructure. (C) 1996 American Vacuum Society.