Removal of moisture contamination from porous polymeric low-k dielectric films

Ultra low-k dielectrics are expected to replace SiO ₂ as the interlayer dielectric for the next-generation microelectronic devices. A challenge facing the integration of these dielectrics in manufacturing is their interactions with gaseous contaminants, such as moisture, and the resulting change in their properties. The physical and chemical interactions of moisture with porous spin-on dielectric material are investigated using temperature- and concentration-programmed exposure and purge sequence together with trace moisture analysis, using atmospheric pressure ionization mass spectrometry. The model compound in this study is methylsilsesquioxane, deposited and treated under typical manufacturing conditions. A process model is developed that provides information on the mechanism and kinetics of moisture uptake and release in thin porous films. The model elucidates the effect of film properties on the contamination uptake as well as outgassing; it also provides a valuable tool for designing an optimum process for contamination control and removal in porous films.