Abstract
Inelastic electron tunneling spectroscopy (IETS) was applied to characterize the microstructure, interface, and trap-related states in silicon metal-oxide-semiconductor devices consisting of high- κ gate dielectrics Hf O2, Y2 O3, and stacked Hf O2 Y2 O3 bilayer by molecular beam epitaxy and atomic layer deposition under various heat treatments. Reproducible vibrational modes of monoclinic Hf O2 and cubic Y2 O3 were identified from IETS spectra, along with phonon modes related to interfacial structures for a given metal-oxide-semiconductor fabrication process. A simple modeling was employed to analyze the trap related features in IETS spectra of stacked Hf O2 Y2 O3 bilayers, and showed that most traps are located near the Hf O2 Y2 O3 interface due to dissimilar charge distributions of two ionic oxides of different cation valences, and the presence of interfacial strains of dissimilar structures. © 2008 American Institute of Physics.