Regensburg 2010 – scientific programme
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O: Fachverband Oberflächenphysik
O 13: Semiconductor substrates: Adsorption
O 13.2: Talk
Monday, March 22, 2010, 15:15–15:30, H34
Thermal stability of ultra-thin ZrO2 films and structure determination of ZrSi2 islands on Si(100) — •Frank Schönbohm1,2, Christian Rolf Flüchter1, Daniel Weier1, Tobias Lühr1, Ulf Berges1,2, Sven Döring1,2, and Carsten Westphal1,2 — 1Experimentelle Physik 1 - Technische Universität Dortmund, Otto-Hahn-Str. 4, D-44221 Dortmund, Germany — 2DELTA - Technische Universität Dortmund, Maria-Goeppert-Mayer-Str. 2, D-44221 Dortmund, Germany
The ongoing miniaturisation of semiconductors requires a substitute for the presently used SiO2 gate dielectrics. Below 2 nm film thickness the leakage current increases drastically due to tunneling processes and causes the loss of efficiency. Among the high-k materials HfO2 and ZrO2 might be proper candidates to replace the SiO2. We studied the temperature dependence of thin ZrO2 films on clean silicon by means of x-ray photoelectron spectroscopy (XPS) and photoelectron diffraction (XPD). ZrO2 films with a thickness of approximately 11 Å were grown by electron beam evaporation on a (2×1)-reconstructed Si(100) surface. At annealing temperatures of 650∘C and above the ZrO2 films were transformed into ZrSi2. The temperature region of structural transformation could be narrowed to the range from 650∘C to 725∘C. During the formation of ZrSi2 all oxygen was removed from the sample surface. After annealing at 725∘C neither zirconia nor silicon oxide could be verified on the sample. From the combined spectroscopy, SEM, and XPD analysis a model for the internal structure of ZrSi2 is proposed.