(Georgia Institute of Technology, 1999)
Kohl, Abbe T.; Mimna, Richard; Shick, Robert; Rhodes, Larry; Wang, Z. L. (Zhong Lin); Kohl, Paul A.
Low dielectric constant, porous silica was made from commercially available methyl silsesquioxane (MSQ) by the addition of a
sacrificial polymer, substituted norbornene polymer containing triethoxysilyl groups (NB), to the MSQ. The silsesquioxane-NB
polymer film mixture was thermally cured followed by decomposition of the NB at temperatures above 400°C. The dielectric constant
of the MSQ was lowered from 2.7 to 2.3 by creating 70 nm pores in the MSQ. The voids created in the MSQ exhibited a
closed-pore structure. The concentration of NB in the MSQ affected the number of pores but not their size. Porous films were also
created in a methyl siloxane spin-on-glass and its dielectric constant was lowered from 3.1 to 2.7. Infrared spectroscopy was used
to follow the curing of the MSQ and decomposition of the NB.