Spectroscopic ellipsometry characterization of ZrO2 thin films by nitrogen-assisted reactive magnetron sputtering

Spectroscopic ellipsometry (SE) with photon energy 0.75-6.5 eV at room temperature has been used to derive the optical properties of high-k ZrO2 thin films on Si(100) substrates prepared by nitrogen-assisted, direct current reactive magnetron sputtering. The Tauc-Lorentz dispersion method was adopted to model the optical dispersion functions of the thin films as a function of annealing temperature. Excellent agreement has been found between the SE fitting results and X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM) and Fourier transform infrared spectroscopy (FTIR) results, indicating that our model adequately described the measured SE data. Optical band gaps (E-g) were also obtained based on the extracted absorption edge. Our results suggest that nitrogen-assisted process can effectively limit the interfacial layer growth in high-k oxides. (c) 2006 Elsevier Ltd. All rights reserved.