Energy-dispersive, x-ray reflectivity density measurements of porous SiO2 xerogels

X-ray reflectivity has been used to measure nondestructively the density of thin, porous, silica xerogels used for interlayer dielectric applications. The critical angle, defined through total external reflection, was measure d for multiple x-ray energies to correct for sample misalignment error in t he determination of the density for the films. This density was used to ext rapolate the percentage porosity, assuming a bulk SiO2 density standard. Th e results were compared to those obtained by Rutherford backscattering and ellipsometry techniques. (C) 2000 American Institute of Physics. [S0003-695 1(00)00702-6].