Annealing-induced evolution in interface stability and electrical performance of sputtering-driven rare-earth-based gate oxides

Abstract

Annealing temperature-dependent ultrathin Dy2O3 gate dielectric films, grown on Si substrates by reactive sputtering, were characterized in terms of structural, optical and electrical properties using x-ray diffraction (XRD), x-ray photoelectron spectroscopy (XPS), UV–Vis transmission spectroscopy and electrical measurements of Dy2O3/Si gate stack. Additionally, the thickness of the interfacial SiO2 layer during the deposition and annealing process has been calculated using the Si 2p XPS spectra to exclude its influence on the electrical parameter of Dy2O3 films. XPS analyses for all the samples have shown the abrupt growth of the Dy-silicate for 700°C-annealed sample, which is identified as the primary reason for the dramatic reduction in its electrical performance. In addition, optimized Dy2O3 sample with annealed temperature at 600 °C exhibits the lowest equivalent oxide thickness of 1.6 nm, the highest dielectric constant 16.8, the lower leakage current density 4.45 × 10−8 A/cm2 and the lower frequency dispersion of 6.21%. Based on the experimental analysis, the optimized annealing temperature has been obtained to achieve Dy2O3 gate dielectric thin films as deposition of high-k with high-quality on Si substrates.