Focused ion beam fabrication of thermally actuated bimorph cantilevers

Focused ion beam (FIB) technology was used to fabricate thermally actuated cantilever arrays using silicon nitride membrane chips for microelectromechanical systems (MEMS) applications. Sequential modification and test is made possible by the dualbeam FIB/SEM. A fabrication route based largely on the use of FIB etch and deposition steps applied to a silicon nitride membrane chip resulted in the formation of readily released bimorph structures with lengths <10 μm. Device deflection sensitivity better than 500 nm/mW was observed. Short-circuiting and hence non-functionality of some devices was attributed to the platinum halo overlap between deposited tracks, which limits the potential for miniaturisation of FIB-MEMS prototypes. Potential applications for these cantilever arrays include scanning probe microscope (SPM) systems and resonant gas sensors.