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Interfacial Effects on Moisture Absorption in Thin Polymer Films



B D. Vogt, Christopher L. Soles, Ronald L. Jones, C M. Wang, Eric K. Lin, Wen-Li Wu, Sushil K. Satija, D L. Goldfarb, M Angelopoulos


Moisture absorption in model photoresist films of poly(4-hydroxystryene) (PHOSt) and poly(tert-butoxycarboxystyrene) (PBOCSt) was measured by x-ray and neutron reflectivity. The degree of swelling in the films upon moisture exposure was found to be dependent upon the film thickness. As the film becomes thinner, the swelling is enhanced. The origin of this deviation was found to be excess water at the polymer/silicon interface, which was directly measured using neutron reflectivity. The film thickness dependent swelling behavior of both PHOSt and PBOCSt can be explained by a simple model consisting of a water rich layer at the polymer/silicon interface and bulk swelling through the remainder of the film. The water rich layer extends (25 10) into the film with a maximum water concentration of approximately 30 % by volume. The excess layer was found to be polymer independent despite the order of magnitude difference in the water solubility in the bulk of the film.
No. 13


absorption, interface, thin film


Vogt, B. , Soles, C. , Jones, R. , Wang, C. , Lin, E. , Wu, W. , Satija, S. , Goldfarb, D. and Angelopoulos, M. (2004), Interfacial Effects on Moisture Absorption in Thin Polymer Films, Langmuir, [online], (Accessed May 23, 2024)


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Created June 1, 2004, Updated February 17, 2017