A CMOS MEMS Gold Plated Electrode Array for Chemical Vapor Detection

This work presents the fabrication and demonstration of an electroless gold plated CMOS-MEMS chemresistor array sensor for selective detection of volatile organic compounds, with conductive polythiophene polymer used as an active sensing material. Chemresistor electrode fabrication involves post-CMOS etching and electroless plating steps. An electroless gold plating process selectively deposits gold onto the CMOS aluminum electrodes to provide ohmic contact to the polymer layer. Electroless gold techniques are optimized to provide for a sub-micron vertical gap between the chemresistor electrodes. Polymer solutions are then deposited onto electrodes using drop-on-demand inkjet printing. Measured device response to methanol, acetone, and acetonitrile vapors demonstrates feasibility.