Structure and Interaction of Organic/Inorganic Hybrid Nanocomposites for Microelectronic Applications. 1. MSSQ/P(MMA-<i>co</i>-DMAEMA) Nanocomposites

Abstract

Nanoporous methyl silsesquioxane (MSSQ), which is an important and promising candidate for spin-on ultralow dielectric constant applications, has been produced via the thermosetting of MSSQ, templated by a nanodispersed, thermally decomposable pore generator (porogen)−poly(methyl methacrylate-co-dimethylaminoethyl methacrylate) [P(MMA-co-DMAEMA)]. Fourier transform infrared spectroscopy is used to study the interaction and structural changes of MSSQ/P(MMA-co-DMAEMA) nanocomposites as a function of curing temperature (ranging from 25 to 450 °C) and porogen loading (ranging from 0 to 70 wt %). We find that strong hydrogen-bonding interactions occur between the −OH end groups in MSSQ and the tertiary amino groups in P(MMA-co-DMAEMA) in films at 25 °C. An increase in cure temperature from 25 to 250 °C and finally to 450 °C transforms MSSQ from a material with many reactive end groups to a highly cross-linked structure. In addition, the amino substituent in P(MMA-co-DMAEMA) can act as a catalyst for the condensation and cross-linking of MSSQ. An increase of porogen loading to 70 wt % and a decrease in the silanol group concentration in MSSQ both hinder the formation of the −Si−O−Si− network. Finally, small-angle X-ray scattering (SAXS) results indicate that MSSQ resins initially having higher −OH end group concentrations ultimately generate smaller pores after the removal of porogens.