The failure mechanisms of micro-scale cantilevers in shock and vibration stimuli

Contemporary shock testing of micro-devices is carried out in controlled test environments where test parameters can be monitored with current metrology techniques. Due to demanding environments and limited scope of design rules, the reliability of micro devices has become a concern. A modified Hopkinson pressure bar (HPB) is used to investigate failure mechanisms of single crystal silicon (SCS) micro-cantilever devices under high-g accelerations. Response upon impact is monitored using high speed imaging (HSI) to ascertain the cause of failure. White light interferometry (WLI) and scanning electron microscopy (SEM) are used as post analysis techniques to investigate cause of failure and fracture topography. The modified HPB method in conjunction with high speed imaging allowed valid prediction of modal and temporal failure information of the micro cantilevers. WLI investigated the effects of deep reactive ion etching (DRIE) etching on crack instigation. SEM identified octahedral cleavage of SCS as the dominant failure mechanism of the micro-cantilevers.