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Regensburg 2007 – scientific programme

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DS: Fachverband Dünne Schichten

DS 26: Oxides

DS 26.11: Talk

Thursday, March 29, 2007, 17:30–17:45, H34

Characterization of GdScO3 layers by Spectroscopic EllipsometryMartin Roeckerath, •Jürgen Moers, Jürgen Schubert, and Siegfried Mantl — Institut of Bio- und Nanosystems, Forschungszentrum Jülich, D-52425 Jülich

For further improvement of MOSFET devices high-κ materials for gate dielectrics are under investigation. Rare earth scandates are drawing increasing attention due to their favorable material properties. The κ-value is above 20, the band offsets to silicon are larger than 2 eV and the layers are stable up to 1000C. To investigate the properties of those materials, Gadolinium scandate (GdScO3) was selected exemplarily. Layers with different thickness were deposited on silicon (HF last) and oxidized (2 nm) silicon by electron beam evaporation. Their stoichiometry and morphology were characterized by Rutherford Backscattering (RBS), X-ray reflectometry (XRR) and transmission electron microscopy (TEM).

In order to provide a quick and non-destructive characterization method, the samples were measured at angles of 50, 60 and 70 by spectroscopic ellipsometry (SE) and the results were compared to the other measurements. The optical data of GdScO3 were described analytically by a Sellmeier formula with 5 parameters. It was found that the measured thicknesses of SE and XRR are in agreement for film thicknesses above 10 nm. Below 10 nm SE overestimates the thickness by far, indicating the increasing influence of the substrate/GdScO3 interface.

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