Small angle x-ray scattering for measuring pore-size distributions in porous low-κ films

A small-angle x-ray scattering technique has been applied for characterizing pore-size distribution in porous low-kappa dielectric films. The data are collected in reflection geometry using offset theta/2theta scans for avoiding strong specular reflections from the film surface and its substrate. The effects of refraction and reflection at the film surface and interface are corrected by the distorted wave Born approximation. A Gamma-distribution mode is used to determine the pore-size distribution in a film. The technique has been used to analyze porous methyl silsesquioxane films. The pore sizes were found to disperse in the range from subnanometer to several nanometers, and the results agree well with those obtained by the N-2 gas adsorption technique. (C) 2003 American Institute of Physics.