Hybrid mold reversal imprint for three-dimensional and selective patterning

Abstract

Three-dimensional (3D) nanostructures are needed in many applications including sensors, actuators, and microanalysis systems. In this work, a novel technology combining UV lithography, hybrid mold, and reversal imprint for fabricating 3D structures is developed. A hybrid mold made from quartz is used. The mold has structures patterned by lithography and dry etching. The quartz mold also has selected patterns formed by 50nm thick Cr. A layer of UV definable SU-8 polymer is spin coated onto the hybrid mold and patterned by optical lithography. The mold with the patterned SU-8 layer and no residue is then transferred to a substrate with topography by reversal imprint with temperatures as low as 50°C and pressures of nominally 2MPa. Depending on the dimensions of patterns on the mold compared to the ones on the substrate and the imprint pressure, patterns can be selectively transferred to substrates through reversal imprint. This technology greatly simplifies the fabrication process and provides more flexibility in building complex 3D structures.