In-plane motion characterization of MEMS resonators using stroboscopic scanning electron microscopy

We present the in-plane characterization of micro-electromechanical systems (MEMS) resonators using a stroboscopic scanning electron microscope (SEM) imaging technique. The system features time-gated sampling of the secondary electron signal in order to achieve stroboscopy, hence dispensing with electron-optical compensation and noise effects associated with front-end electron beam blanking. We demonstrate its capability in phase-resolved motion freezing and displacement tracking as well as time-resolved velocity estimation of a MEMS electrostatic comb drive resonator. The stroboscopic imaging system is able to obtain a full profile of the resonator's displacement with an accuracy of 20 nm over one and several cycles of its motion, along with estimates of the resonator's instantaneous velocity at various phases of its motion down to about 0.012 m s−1.