Instabilities in Focused Ion Beam-patterned Au nanowires

Abstract

Focused Ion Beam (FIB) technology has become an indispensable enabling tool for micro nano fabrications. One important application is to use FIB for patterning conducting nanowires of metals down to a few tens of nanometre for applications such as interconnects, heaters and temperature nanosensors. A series of experiments on Au nanowires fabricated by FIB on Si x N y membrane show that nanowires with width ⩽50 nm have structural instabilities. These are liquid like and first show-up as undulations in nanowire width with clearly defined wave lengths. For smaller widths (∼20 nm) the instabilities grow and the wires eventually break-up into spherical balls. Further experiments show that the nanowires can be made stable to smaller widths by the use of a Cr underlayer to enhance surface wetting. The observed behaviour is due to the Rayleigh-Plateau instability which occurs for systems in which surface energy dominates.