Low k, Porous Methyl Silsesquioxane and Spin-On-Glass
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.