Thermo-mechanical characterization of materials at micro/nanoscale under bending

This paper presents a new method for testing materials at the microscale at high temperature under bending in-situ in SEM. The proposed method consists of a straining stage with built-in force and displacement sensors attached to a heating stage inside the SEM. The sample is co-fabricated with the stage to eliminate any misalignment error. The method is applied to test the strength of single crystal silicon (SCS) micro-beams under bending. At room temperature, bending tests revealed strengthening of SCS compared to that under uniform tension. This strengthening is contributed by stress localization near the surface of the beams close to the anchors, and the stress gradient from the surface to the neutral axis. The study further reveals significant reduction in the Brittle to Ductile Transition (BDT) temperature of SCS micro-beams compared to their bulk counterparts.