Enhancing the Crystallization and Properties of the SrRuO₃ Electrode Film Grown by Atomic-Layer-Deposited SrO and Pulsed-Chemical Vapor-Deposited RuO₂ through Al Substitution

Abstract

SrRuO 3 (SRO) is a promising electrode material for the next-generation dynamic random access memory (DRAM) capacitor. This study focuses on the properties of SRO electrode films grown by combining the atomic-layer deposition of SrO and pulsed-chemical vapor deposition of RuO 2 component layers using Sr( i Pr 3 Cp) 2 ( i Pr 3 Cp = 1,2,4-trisisopropyl-cyclopentadienyl) and RuO 4 precursors, respectively. Changes in the Ru concentration and electrical properties of SRO electrode films during postdeposition annealing (PDA) for crystallization were examined in detail. SRO films were crystallized after PDA in an O 2 atmosphere, but the Ru concentration of SRO films was decreased due to volatile RuO 4 formation. Also, the morphology of the film was degraded by agglomeration, which degraded the film′s performance. A thin Al 2 O 3 film was deposited on or inserted into Ru and SRO films, and its effects on Ru-loss and crystallization were experimentally and theoretically investigated. The density functional theory calculation confirmed that Al substituted with Ru (Al Ru ) in the SRO film improved the crystallinity of cubic SRO. Thus, the Al 2 O 3 -layer-inserted or Al-substituted SRO films had a larger grain size, higher crystallinity, and improved surface morphology and maintained a lower resistivity down to 25 nm (∼1000 μΩ•cm).