Characterization of chemical-vapor-deposited low-k thin films using x-ray porosimetry

Trimethylsilane-based carbon-doped silica films prepared with varying chemical-vapor-deposition process conditions were characterized using x-ray reflectivity and porosimetry to measure the film thickness, average film density, density depth profile, wall density, and porosity. Samples deposited under single or dual frequency conditions with either N2O or O-2 as an oxidant were compared. The structural parameters were correlated with the chemical bond structure measured by Fourier transform infrared spectroscopy. The density profiles of the porous films were uniform with a slight densification at the film surface. The distribution of pores was also uniform through the film. Films prepared under a single frequency and/or N2O atmosphere had the lowest film density, wall density, and dielectric constant. The porosities of the films were similar and the pore sizes were less than 10 Angstrom. (C) 2003 American Institute of Physics.