Porous SiO2 films derived from a novel organic-inorganic composite sol-gel process were studied for possible applications in the microelectronics industry. The films were capped with plasma-enhanced chemical-vapor-deposited silicon nitride and characterized using ellipsometry, IR spectroscopy and cross-sectional transmission electron microscopy (TEM). TEM cross-sections were prepared using a focused ion beam (FIB) system, because traditional TEM preparation by polishing was too harsh for the fragile samples. The TEM analysis determined the film thickness to be 155 nm for SiO2 and 83 nm for Si3N4, and showed high porosity in the SiO, film and vertical pores in the Si3N4 film.