Electron energy -loss spectroscope, has been used to investigate the interface between a Y2O3 film and the silicon substrate. The chemical composition of the interface layer is revealed to be nearly pure amorphous SiO2. Yttrium silicates are found at the Y2O3/SiO2 interface region. The fort-nation of the interfacial yttrium silicates has been interpreted by the direct chemical reaction between the deposited Y2O3 film and the SiO2 interface layer. The Si L-23 and O K edges of yttrium silicates (Y2SiO5 and Y2Si2O7) have been calculated by the first-principle full multiple scattering method. The theoretical results are consistent with the experimental spectra, which confirms the formation of yttrium silicates. (c) 2005 Elsevier B.V. All rights reserved.