Dresden 2020 – scientific programme
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DS: Fachverband Dünne Schichten
DS 39: Thin Oxides and Oxide Layers II (joint session DS/HL)
DS 39.5: Talk
Thursday, March 19, 2020, 12:00–12:15, CHE 91
TiOx formation during ALD metal oxide growth on Ti for resistive switches — •Ivonne Bente, Stephan Außen, and Susanne Hoffmann-Eifert — Peter Grünberg Institut, Forschungszentrum Jülich GmbH
We studied the formation of TiOx at the interface of Ti metal and a metal oxide film, which is grown onto the Ti layer by atomic layer deposition (ALD). For the metal oxide we investigated stoichiometric oxide films (MO) including Al2O3, TiO2 and HfO2 layers. The 25 nm thick dense Ti films are deposited on thermal oxidized Si wafers in an off-axis sputter tool with a base pressure < 10−10 mbar. The Ti films with hexagonal crystal structure exhibit a low surface roughness. The films were transferred under ultra-high vacuum into an ALD plasma system. 2 to 3 nm thick oxide layers are deposited at 250∘C using O2-plasma as the oxygen source and standard metalo-organic precursors for the metal sources. The resulting stacks are investigated by x-ray photoelectron spectroscopy showing different Ti oxidation states (0 to 4+) and a clear TiOx thickness dependence on the ALD process. The switching behavior of the resulting stacks is investigated. In addition, complementary resistive switching experiments are performed on equivalent stacks, i.e. Pt/MO/TiOx/Ti. The correlation between the XPS results and the resistive switching characteristics (pristine leakage current, electroforming voltage, etc.) is discussed.