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SANS and XRR Porosimetry of a Polyphenylene Low-k Dielectric



M S. Silverstein, Michael Shach-Caplan, Barry J. Bauer, R C. Hedden, V. J. Lee, B G. Landes


Nanometer scale porosity is being introduced into low-k dielectrics in an attempt to achieve the permittivities of less than 2.0. X-ray reflectivity (XRR) solvent porosimetry and small angle neutron scattering (SANS) contrast match solvent porosimetry can be used to describe the pore size distributions (PSD) in such materials. This paper investigates applying a combination of SANS and XRR porosimetries to characterize the PSD in a polyphenylene low-k dielectric, describing an approach which has not been explored previously. Previous descriptions of these materials based on SANS in vacuum assumed a PSD with a single peak. The intensity varies as q-2 in contrast match solvent SANS, indicating the existence of a single phase with relatively large scale concentration fluctuations.The structure in a film with partially developed porosity, containing both pores and porogen, was for the first time described using a combination of contrast match SANS and solvent absorption XRR. Both SANS and XRR porosimetry indicate the presence of a bimodal PSD. The PSD peak at about 5 from XRR porosimetry indicates that SANS is less sensitive to structure at high q, relatively small size scales, such as solvent absorbed in the matrix free volume. The observed sorption/desorption hysteresis indicates the presence of ink-bottle pores in which solvent-filled small pores block the desorption from large pores until lower partial pressures are reached.
39 No 8


low-k, nanoporous, polyphenylene, porogen, SANS, XRR


Silverstein, M. , Shach-Caplan, M. , Bauer, B. , Hedden, R. , Lee, V. and Landes, B. (2006), SANS and XRR Porosimetry of a Polyphenylene Low-k Dielectric, Macromolecules, [online], (Accessed July 13, 2024)


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Created April 1, 2006, Updated February 17, 2017