Microfabrication and characterization of UV micropatternable, electrically conducting polyaniline photoresist blends for MEMS applications

Abstract

We present the preparation and electrical characterization of an electrically conductive blend of polyaniline (PANi) and SU-8 UV micropatternable photoresist that offers promising opportunities for MEMS applications. The blend was prepared by shear mixing of PANi and SU-8 2010 resist at an rpm of 1,000 for 15 h. The composite was spin-coated on a silicon wafer at an 850 rpm in order to achieve a thickness of 50 µm, followed by soft baking at 70 °C for 35 min and cooling to room temperature. The desired structures were patterned using masked UV exposure for 60 s. Full cross-linking of PANi and SU-8 blend was achieved by a post-exposure bake at a temperature of 90 °C for 25 min, followed by cooling to room temperature. The desired electrode structures and trace lines were then developed in SU-8 developer for 10 min by manual agitation. The fabricated structures were characterized under Scanning Electron Microscope and through Electron Dispersion X-ray Spectroscopy (EDS) demonstrating that good patternability was achieved when using photo-initiator (triarylsulfonium hexafluoro-anitimonate salts) and gamma-butyrolactone solvents in the blend. Further, electrical characterization together with EDS showed that an electrically conductive path is formed in the PANI SU-8 2010 polymer matrix. It is also observed that resistivity as low as 350 ?-m was achieved at 8.6 wt% of PANi in SU-8 2010 polymer matrix.