Neutron reflectivity on nanoporous poly(methylsilsesquioxane) thin films

The depth porosity profile of nanoporous poly(methylsilsesquioxane) thin films was investigated with neutron reflectivity using toluene-d8 or D2O as probes. The nanoporous films show a selective sorption behavior and swell when they are exposed to the selective solvent. The results show a localized higher porosity at the interface between porous films and silicon substrates, which suggests more careful control of the spatial pore distribution is needed to meet the thermo-mechanical stability requirements of porous low-k materials.