Dielectric and optical properties of Zr silicate thin films grown on Si(100) by atomic layer deposition

Abstract

Dielectric and optical properties of (ZrO2)x(SiO2)1−x dielectric thin films, grown on Si(100) by the atomic layer deposition method, were studied by means of reflection electron energy loss spectroscopy (REELS). The quantitative analysis of REELS spectra was carried out by using the quantitative analysis of electron energy loss spectra-ε(k,ω)-REELS software to determine the dielectric function and optical properties by using an analysis of experimental REELS cross sections from the simulated energy loss function (ELF). For ZrO2, the ELF shows peaks in the vicinity of 10, 15, 21, 27, 35, 42, and 57 eV. For SiO2, a broad peak at 23 eV with a very weak shoulder at 15 eV and a shoulder at 34 eV were observed, while for Zr silicates (x=0.75 and 0.5), the peak position is similar to that of ZrO2. For Zr silicates with high SiO2 concentration (x=0.25), the peak positions are similar to that of SiO2, but the peak at 42 eV, which is due to excitation of Zr N2,3 shell electrons, still exist. This indicates that the dielectric and optical properties of ZrO2 thin films are dominating the dielectric and optical properties of Zr silicates even for high SiO2 concentrations. In addition, the inelastic mean free path (IMFP) was also calculated from the theoretical inelastic cross section. The IMFP of Zr silicates increases with increasing Zr composition in Zr silicates, and they also increase with increasing primary energy. The method of determining the dielectric and optical properties and IMFP from the ELF turns out to be a convenient tool for ultrathin high-k materials.