Electron energy-loss spectroscopy analysis of interface structure of yttrium oxide gate dielectrics on silicon

Interface stability of high dielectric constant gate insulators on silicon is an important issue for advanced gate stack engineering. In this article, we analyze the silicon/dielectric interface structure for thin Y₂O₃ and Y silicate films deposited by chemical vapor deposition on clean and prenitrided Si(100) using high-resolution transmission electron microscopy, electron energy-loss spectroscopy, and x-ray photoelectron spectroscopy. The analysis shows the films to be stoichiometric Y₂O₃ on top and Y-silicate/SiO₂ at the dielectric/Si interface. Prenitridation of the silicon surface impedes the reaction between the depositing film and the substrate, promoting a Si-free Y₂O₃ structure. Possible mechanisms leading to the observed Y₂O₃ and Y silicate structures are discussed. © 2002 American Institute of Physics.