Improving the Properties of SrRuO₃ Electrode Films Grown by Atomic Layer-Deposited SrO and Pulsed Chemical Vapor-Deposited RuO₂ Using Al₂O₃ Capping Layers

Abstract

In this study, an Al 2 O 3 capping layer (ACL) was utilized to enhance the surface morphology and electrical properties of SrRuO 3 (SRO) electrode films deposited via combined atomic layer deposition and pulsed chemical vapor deposition. To crystallize the SRO films, postdeposition annealing (PDA) was necessary; however, this led to material agglomeration and degradation of the surface morphology. Therefore, to address this issue, the ACL was used to reduce agglomeration by inhibiting material migration. Next, the appropriate thickness of ACL and PDA conditions, which ensured high crystallinity and suppressed agglomeration, were investigated. Subsequently, the ACL was wetetched using an aqueous HF solution. The changes in the layer density of Ru and Sr were analyzed, and the stoichiometric SRO film was stably obtained after PDA and wet-etching. The resulting ACL-etched SRO film had an improved surface morphology, lower resistivity (∼800 μΩ•cm), and lower root-mean-squared roughness (1.15 nm) compared to uncapped SRO films at a thickness of 25 nm. Finally, the atomic layer-deposited SrTiO 3 dielectric layer on the SRO film was in situ-crystallized, with a high dielectric constant of 81 and a minimal interfacial equivalent oxide thickness of 0.03 nm.