Fabrication of an array of microcavities utilizing SU-8 photoresist as an alternative `LIGA' technology

This paper reports the use of SU-8 photoresist in the formation of an array of microcavities in polystyrene for biochemistry and combinatorial chemistry applications. Fabrication of the array involves hot embossing of polystyrene utilizing a nickel-cobalt micro-mold electroformed from the original SU-8 structure. For the particular applications being considered, the volume of the cavities necessitates a cavity depth of 100 microns. While conventional LIGA technology could be used, the use of a photoimageable spin-on layer capable of defining structures at a thickness well over 100 microns has greatly simplified the procedure. Additionally, such a method can put LIGA type processing in the hands of researchers without ready access to a synchrotron source. As such, this paper will cover the technical details of using SU-8 photoresist as it applies to the fabrication of a thermoplastic bio-MEMS structure.