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Updated: Jul 13, 2026

Micropunching Lithography for Generating Micro- and Submicron-patterns on Polymer Substrates
Published on: July 2, 2012
Multi-layering of SU-8 exhibits distinct geometrical transitions from circular to planarized profiles
Martin Sauzade1, Ling Li1, Tomasz Bakowski1
1Department of Biomedical Engineering, Stony Brook University, Stony Brook, New York 11794, USA.
Abstract:
The negative tone photoresist SU-8 permits the creation of micrometer-scale structures by optical lithography. It is also the most used photoresist in soft lithography for the fast-prototyping of microfluidic devices. Despite its importance, the effect of capillary forces on SU-8 multi-layering onto topographical features has not been thoroughly studied. In particular, the profile of the added layer has not been examined in detail. The overlaying process exhibits a set of distinct behaviors, or regimes, depending on the relative thickness of the overlay and the underlying rectangular pattern. We demonstrate how capillary effects control the profile of multi-layer microchannels in a predictable manner. We derive a simple static model to describe the evolution of the overlay as a function of dimensionless geometric parameters. Our study provides a critical understanding of the parameters that govern multi-layer spin coating.
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