Soft-lithographic replication of 3D polymeric microstructures created with MAP

Abstract

Considerable effort has gone into the development of techniques for three-dimensional fabrication. A particularly promising class of techniques for creating 3D structures relies upon the use of multiphoton absorption. In multiphoton absorption polymerization (MAP), 3D structures are created on a point-by-point basis by hardening a prepolymer resin with a tightly focused laser beam. While MAP offers the capability of creating arbitrarily complex 3D structures with feature sizes on the order of 100 nm, it is inherently a serial technique. In order to scale this technique up for mass production of microstructures, it will be necessary to develop a means for parallelizing the creation of structures on the wafer scale. One promising avenue for attaining this goal is the use of soft lithography, in the form of microtransfer molding (&mgr;TM). However, in the past &mgr;TM has been limited to the reproduction of "2.5D" structures, i.e. those without closed loops. We have developed a new technique called membrane-assisted microtransfer molding (MA-&mgr;TM) that can circumvent the closed-loop issue, allowing for the replication of truly 3D structures.