Berlin 2008 – wissenschaftliches Programm
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DS: Fachverband Dünne Schichten
DS 23: High-k Dielectric Materials - Synthesis, Properties, Applications
The posters can also be presented at Poster A on Tuesday morning (DS poster session).
DS 23.8: Poster
Mittwoch, 27. Februar 2008, 18:30–20:30, Poster C
Optical characterization of HfO2-based high-k gate stacks — •Martin Weisheit, René Hübner, Hans-Jürgen Engelmann, Inka Zienert, Susanne Ohsiek, Kornelia Dittmar, Michael Hecker, Martin Trentzsch, and Ehrenfried Zschech — AMD Saxony LLC & Co. KG, Wilschdorfer Landstraße 101, 01109 Dresden
HfO2 is currently introduced as a high-k gate dielectric into large scale semiconductor production of logic devices. Along with HfO2, a number of other new materials will have to be introduced into the gate stack, namely ultrathin work function layers and metal gates. This results in a complex gate stack that challenges traditional characterization techniques. In this presentation we demonstrate how a combination of complementary methods allows quantitative determination of relevant parameters. Important information can be derived from the optical properties of the stack - such as the bandgap of the HfO2 - which are measured by Variable Angle Spectroscopic Ellipsometry (VASE). However, due to the very thin individual layers of the stack, independent determination of thickness and refractive index is difficult. Therefore, TEM and X-Ray Reflectivity are needed as complementary methods for an accurate measure of the layer thicknesses. Using the Drude model, VASE is then employed to characterize the electrical conductivity of the TiN metal gate layers, which is compared to Microscopic Four-Point Probe measurements and discussed with respect to chemical composition as determined by XPS and Auger electron spectroscopy. The work described in this presentation has been funded in line with the technology funding for regional development (ERDF) of the European Union and by funds of the Free State of Saxony.