Dresden 2009 – scientific programme

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DS: Fachverband Dünne Schichten

DS 22: Organic Thin Films II

DS 22.5: Talk

Wednesday, March 25, 2009, 12:15–12:30, GER 38

Effects of annealing and UV irradiation on pulsed laser deposited PMMA films — •Britta Lena Fuchs, Andreas Meschede, and Hans-Ulrich Krebs — Institut für Materialphysik, Universität Göttingen, Friedrich-Hund-Platz 1, D-37077 Göttingen

Smooth thin films of Poly(methyl methacrylate) (PMMA) are of interest as photoresist or for coating applications. Here pulsed laser deposition (PLD) at a wavelength of 248 nm is used at low laser fluences slightly above the deposition threshold of PMMA (between 80 and 160 mJ cm⁻²) to prepare completely smooth films free of droplets [1]. The chemical behaviours were measured by infrared spectroscopy (FTIR) and size exclusion chromatography (SEC). By indentation measurements we find that these films are very soft after preparation and possess a universal hardness of only HU=5 N mm⁻². But after UV irradiation a strong hardening of the PMMA films occurs due to a higher cross-linking of the polymer. When depositing the PMMA films at higher substrate temperatures, we also observe a hardening of the films (above 200 N mm⁻²). But additionally a strong dewetting from the substrates occurs. Above 250 ^∘C partial evaporation of the polymer becomes observable and the FTIR specra do not show the characteristic vibration bands any more.

[1] B. Lösekrug, A. Meschede, H.U. Krebs, Appl. Surf. Sci. 254 (2007) 1312