Combination of direct laser writing and soft lithography molds for combined nano- and microfabrication

Abstract

This work presents a novel approach for combined micro-and nanofabrication based on the local laser exposure of an UV-curing material through a structured mold. The proposed process makes use of the high freedom of design of direct laser writing (DLW) and the high resolution of soft lithography molds (made e.g. from PDMS). By optimizing the exposure process it was possible to fabricate locally defined hierarchical structures with a height of around 16 µm, that are fully covered with nanometer-sized holes using OrmoComp ® . Manual test imprints showed that the fabricated structures can be used for "step & repeat" nanoimprint processes. Furthermore, the local transfer of nanostructures into two different soft lithography resists (Katiobond 110707, mr-NIL210) was investigated. Diffusion of resist components into the PDMS mold was observed and could be prohibited by the use of hybrid molds, which employ OrmoComp ® as structure containing layer. First experiments revealed successful transfer of the mold's nanostructures into mr-NIL210 but still leave room for improvement concerning the process parameters.

Large area manufacturing of plasmonic colour filters using substrate conformal imprint lithography

“…Based on the dimensions of the master structures given in the Experimental section, a resist layer of around 180 nm should allow for the complete filling of the mould and the formation of a minimal residual layer. However, we were able to show in a previous study that the substantial diffusion of Katiobond 110707 into PDMS moulds can lead to the formation of filling defects [33]. Therefore, the resist loss due to the diffusion effect has to be taken into account when choosing the appropriate coating parameters for the imprint process.…”