Synchrotron x-ray studies of vitreous SiO 2 over Si(001). I. Anisotropic glass contribution
Contributors: M. Castro-Colin, W. Donner, S.C. Moss, Z. Islam, S.K. Sinha, Robert J. Nemanich, H.T. Metzger, P. Boescke, and T. Shulli
ABSTRACT
While numerous investigations of the structure and interface of amorphous SiO2 thermally grown on Si, theoretical as well as experimental, have been carried out over the years, a definitive picture of this thin gate oxide and its interface remains lacking. We have explored this issue using synchrotron x rays in grazing incidence geometry. In this geometry, a fourfold modulation in the first sharp diffraction peak (FSDP) from thin vitreous SiO2 of 100 and 500 Å thickness can be observed. While the FSDP exhibits a modulation throughout the entire film, this modulation decays away from the interface. Reflectivity measurements were also performed, which reveal an interfacial layer of 3% density increase in theSiO2 film over the bulk (film) density.