Supercritical CO2 extraction of porogen phase: An alternative route to nanoporous dielectrics

J. A. Lubguban, S. Gangopadhyay, B. Lahlouh, T. Rajagopalan, N. Biswas, J. Sun, D. H. Huang, S. L. Simon, A. Mallikarjunan, H. C. Kim, J. Hedstrom, W. Volksen, R. D. Miller, M. F. Toney

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16 Scopus citations


We present a supercritical CO2 (SCCO2) process for the preparation of nanoporous organosilicate thin films for ultralow dielectric constant materials. The porous structure was generated by SCCO2 extraction of a sacrificial poly(propylene glycol) (PPG from a nanohybrid film, where the nanoscopic domains of PPG porogen are entrapped within the crosslinked poly(methylsilsesquioxane) (PMSSQ) matrix. As a comparison, porous structures generated by both the usual thermal decomposition (at approximately 450 °C) and by a SCCO 2 process for 25 and 55 wt% porogen loadings were evaluated. It is found that the SCCO2 process is effective in removing the porogen phase at relatively low temperatures (<200 ° C) through diffusion of the supercritical fluid into the phase-separated nanohybrids and selective extraction of the porogen phase. Pore morphologies generated from the two methods are compared from representative three-dimensional (3D) images built from small-angle x-ray scattering (SAXS) data.

Original languageEnglish
Pages (from-to)3224-3233
Number of pages10
JournalJournal of Materials Research
Issue number11
StatePublished - Nov 2004


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