Effects of UV cure on glass structure and fracture properties of nanoporous carbon-doped oxide thin films

The effects of UV radiation curing on the glass structure and fracture properties were examined for a class of nanoporous organosilicate low dielectric constant films. A detailed characterization by nuclear magnetic resonance spectroscopy and Fourier transform infrared spectroscopy showed significant changes in the glass structure with increasing curing time, marked by the removal of terminal organic groups and increased network-forming bonds following the initial removal of porogen material. The higher degree of film connectivity brought about by an increased cure duration is demonstrated to significantly enhance adhesive fracture properties and to moderately improve cohesive fracture resistance. Explanations for the enhanced fracture behavior are considered in terms of the glass structure. The important role of crack path selection during adhesive and cohesive fracture processes is used to rationalize the observed behavior.