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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 28: POSTERS Interfaces and Thin Films
CPP 28.23: Poster
Wednesday, March 25, 2009, 17:00–19:00, P3
Transient waviness of polymer films during spin-coating — •Joerg Pfeifer1, Stefan Walheim2, and Thomas Schimmel1,2 — 1Institute of Applied Physics and DFG-Center for Functional Nanostructures (CFN), Universität Karlsruhe, Germany — 2Institute of Nanotechnology (INT), Forschungszentrum Karlsruhe, Germany
The development of roughness (waviness) during spin-coating of polymer films is a well known phenomenon of high technological relevance. We have investigated the transient formation of such waves in film thickness using time-resolved light reflectance measurements during the spin-coating process. Our model system (Polystyrene (PS) in Cyclohexane) develops this instability during the last 200 milliseconds of the drying process. By controlling the process atmosphere containing a defined load of solvent vapour, the formation and recovery of film waviness (wavelength: 20-50 micron) was observed. In this way, we were able to pre-adjust the amplitude of the developing waves from zero to 100 nm in films with an average thickness of 200 nm. The results of our quantitative investigations give rise to a model of solvent-polymer phase separation during spin-coating as the driving mechanism for this widely observed instability.