Pattern formation in hot embossing of thin polymer films

Abstract

We have investigated pattern formation of thin PMMAfilms during both hot embossing and demoulding of micro- andnanostructures. During filling of the stamp cavities,compressive and capillary effects were observed, and undercertain conditions periodic patterns with characteristic lengthscales formed. In unstructured stamp regions the form of thesepatterns is affected by local differences in the pressure. Forstructured stamps, the self-assembly is strongly influenced bythe size and the shape of the stamp cavities. Rapid expansionof trapped air resulted in viscous fingering patterns and adewetting behaviour of the polymer could be observed.