Applied Physics Letters · 2007 · 11 citations · 8 references
Natural SciencesMaterials EngineeringMaterials ScienceInterface ScienceSurface ScienceThin FilmsAtomic Layer DepositionPlasma-surface InteractionsSurface CrystallographySurface PhysicsThin-film DepositionThin-film MaterialsCrystallization BehaviorPlasma-assisted OxidationPlasma-enhanced Atomic Layer DepositionPlasma-enhanced DepositionReactivityThermodynamic AnalysisThin Oxide FilmsThin Oxide Layers
The thermodynamic properties and interfacial characteristics of HfO2 thin films that were deposited by the direct plasma atomic layer deposition (DPALD) method are investigated. The as-deposited HfO2 films that were deposited by the DPALD method show crystallization of the HfO2 layers, which initiates at approximately the 35th cycle (about 2.8nm) of the DPALD process. Medium-energy ion scattering analysis reveals that the direct O2 plasma causes a compositional change in the interfacial layer as the process progresses. With an increase in the number of process cycles, the Si content decreases and the O content increases at that position, so that the HfO2-like Hf-silicate layer is formed on top of the interfacial layer. The enhanced physical reactivity of the oxygen ions in the direct plasma and the Hf-silicate layer may be the driving forces that accelerate the early crystallization of the HfO2 layer in the DPALD process in the as-deposited state.
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