Regensburg 2007 – wissenschaftliches Programm

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DS: Fachverband Dünne Schichten

DS 26: Oxides

DS 26.1: Vortrag

Donnerstag, 29. März 2007, 15:00–15:15, H34

XPS study of Pr-aluminate high-k dielectric layers on titanium nitride — •Grzegorz Lupina, Thomas Schroeder, Christian Wenger, Gunther Lippert, Jarek Dabrowski, and Hans-Joachim Müssig — IHP, Im Technologiepark 25, 15236 Frankfurt/Oder

To extend the scalability of deep trench capacitor-based dynamic random access memories (DRAM), the introduction of high-k dielectrics-based metal-insulator-metal (MIM) storage capacitors is required. Pr-enriched Al₂O₃ dielectrics with TiN electrodes appear as a promising materials system for this application. Electrical measurements performed on this materials combination show that the development of a capacitor with a very high capacitance density and low leakage current requires a very careful control of the electrode/dielectric interface. For this purpose, we carried out a synchrotron radiation x-ray photoelectron spectroscopy (SR-XPS) study to non-destructively investigate interface reactivity of the Pr_xAl_2−xO₃ (x = 0, 1, 2) dielectrics with TiN metal electrodes. The depth profiling study using SR-XPS shows that the TiN substrate is covered with a native TiO₂. Additionally, a thin interfacial TiON layer is present between these compounds, resulting in a TiN/TiON/TiO₂ materials stack. Molecular beam deposition of Al₂O₃ onto substrates of this structure leads to the reduction of the native TiO₂. In contrast, in the same way deposited PrAlO₃ and Pr₂O₃ dielectrics are significantly less reactive towards TiO₂.