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Notwithstanding its excellent properties such as high work function and low resistance, Ru has not been widely applied in the preparation of electrodes for various electronic devices. This is because of the occurrence of severe morphological degradation in the actual devices employing Ru. Herein, we investigated Ru chemistry for electrode application and the degradation mechanism of Ru during subsequent processes such as thin film deposition or thermal annealing. We revealed that subsurface oxygen induces Ru degradation owing to the alteration of Ru chemistry by the pretreatment under various gas ambient conditions and due to the growth behavior of TiO2 deposited via atomic layer deposition (ALD). The degradation of Ru is successfully ameliorated by conducting an appropriate pretreatment prior to ALD. The TiO2 thin film deposited on the pretreated Ru electrode exhibited a rutile-phased crystal structure and smooth surface morphology, thereby resulting in excellent electrical properties. This paper presents an important development in the application of Ru as the electrode that can facilitate the development of various next-generation electronic devices.

Capacitors based on ABO3-type perovskite oxides show considerable promise for overcoming the limitations of nanoscale integration with dynamic random access memory (DRAM) devices. Among the thermodynamically stable perovskite oxides, titanates (ATiO3) exhibit high dielectric permittivity in metal–insulator–metal (MIM) configurations. However, their performance in mitigating the large leakage current caused by their narrow bandgap (3 eV) remain under scrutiny. Herein, substantially enhanced dielectric properties of an epitaxial SrRuO3/Ba0.5Sr0.5TiO3/SrRuO3 MIM capacitor with a thin dielectric layer (10 nm) are reported. The dielectric/electrode heterointerface was engineered to realize a capacitor with a low leakage current and high dielectric permittivity. A pit-free and stoichiometric SrRuO3 bottom electrode with an atomically smooth surface was exploited to suppress defect formation at the heterointerface. The critical roles of oxygen vacancies and substituted transition-metal atoms in determining the leakage current were assessed, and a strategy for reducing the leakage current via interface engineering was established. Consequently, a dielectric permittivity of 861 and a leakage current density of 5.15 × 10−6 A/cm2 at 1 V were obtained with the thinnest dielectric layer ever reported. Our work paves the way for the development of perovskite-oxide-based capacitors in next-generation DRAM memories.

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