Highly Textured (100) RuO₂/(001) Ru Multilayers Prepared by Sputtering

(001)-oriented Ru films were prepared on SiO₂/Si substrates by rf magnetron sputtering using a mixed gas of Ar and O₂ with an appropriate O₂ flow ratio which was lower than that required for RuO₂ formation. Oxygen atoms are believed to play a role as a surfactant and to enhance single oriented growth of Ru films. Next, highly (100)-oriented RuO₂ films were deposited on the Ru films by reactive sputtering. The (100)-oriented growth of the RuO₂ films is thought to originate from local epitaxial growth on (001)-oriented Ru grains because the mismatch between superlattices of Ru (001) and RuO₂ (100) planes is small. Full-widths at half maximum (FWHMs) of 1.8° and 2.1° were obtained for the X-ray diffraction (XRD) rocking curves of Ru (002) and RuO₂ (200) peaks, respectively. The highly textured RuO₂/Ru electrodes are expected to be useful for dynamic random access memory (DRAM) and ferroelectric random access memory (FeRAM) technologies.