RuO₂ Thin Films as Bottom Electrodes for High Dielectric Constant Materials

Abstract

Ruthenium dioxide (RuO2) thin films are evaluated as bottom electrode for dielectric SrTiO3. It was found that a RuO2 (50nm) / Ru (20nm) barrier layer on a Si substrate is effective as an oxygen barrier layer and as a metal diffusion barrier layer for sputter deposited SrTiO3 films at substrate temperature of 450°C. To test suitability for high temperature processes, RuO2/Ru electrodes were annealed in air at 600°C. 100nm-thiick RuO2 was sufficient to prevent oxygen diffusion. After annealing in the same condition, the leakage current of sputter deposited SrTiO3 (150nm) on RuO2(50nm) / Ru(50nm) was 7.6 × 10 −9 (A/cm2) at 2V.