Ruthenium oxide electrodes prepared by sol-gel spin-coating

Ruthenium oxide thin films were obtained by sol-gel spin-coating. The precursor solution was prepared by dissolving an aqueous solution of ruthenium nitrosyl nitrate Ru(NO)(NO 3 ) 3 into 2-methoxyethanol. Sols exhibiting appropriate viscosity were spin coated onto (100) Si wafers at 4000 rpm for 30 s following by drying at 300°C for 10 min, and repeated 5 ∼ 15 times. The coated wafer was then fired at 400 ∼ 800°C for 3 h in air. Crystallized homogeneous RuO 2 films were obtained below 300°C, and further heating at higher temperature improves the crystallinity. The resistivity of the films regularly decreases from 270 μΩcm to 200 μΩcm as the film thickness increases from 150 nm (5 successive coatings) to 450 nm (1 successive coatings). In addition the resistivity remains almost constant up to 700°C. These RuO 2 thin films are to be used as bottom electrodes for the sol-gel deposition of SrBi 2 Nb 2 O 9 ferroelectric films.