Berlin 2018 – scientific programme

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DS: Fachverband Dünne Schichten

DS 11: Thin Film Properties: Structure, Morphology and Composition (XRD, TEM, XPS, SIMS, RBS, AFM, ...): Session II

DS 11.9: Talk

Tuesday, March 13, 2018, 11:45–12:00, H 0111

Hafnium oxide interface formation during ALD oxide growth on pure Hf films for resistive switches — •Stephan Aussen, Alexander Hardtdegen, Thomas Heisig, Christoph Bäumer, Regina Dittmann, and Susanne Hoffmann-Eifert — Peter Grünberg Institut and JARA-FIT, Forschungszentrum Jülich GmbH, 52425 Jülich, Germany

Oxygen exchange and drift/diffusion processes play a major role in redox-based resistive switching random access memories. Therefore, understanding oxidation/reduction reactions taking place already during the growth process is of utmost importance. In this study we investigate the oxidation behavior of pure Hf during atomic layer deposition (ALD) of stoichiometric oxide films (M′O) as Al₂O₃, TiO₂ and HfO₂ and the switching behavior of the resulting stacks. 25 nm thick sputtered Hf films with a low surface roughness < 0.2 nm were transferred under ultra-high vacuum conditions into an ALD system. Oxide layers were deposited at temperatures between 160 ^∘C and 280 ^∘C from amino-based precursor and O₂-plasma. The resulting stacks were investigated by angle resolved X-ray photoelectron spectroscopy to determine the thickness of the formed interfacial HfO_x layer as well as the valence states of the involved metal cations. The effect of the different ALD processes, e.g. Al₂O₃ as passivation layer, and influence of the temperature on Hf oxidation are discussed. In addition, complementary resistive switching experiments performed on equivalent stacks, i.e. Pt/M′O/HfO_x/Hf, revealed influence of the HfO_x interface formation on the switching behavior.