Characterization techniques for NEMS/MEMS devices

Abstract

In this work, three useful techniques for dynamic motion characterization of MEMS devices are presented, namely network analyzer, acoustic phonon detection and stroboscopic SEM techniques. Proof-of-concept experiments using an MEMS electrostatic resonator reveal reliable and consistent measurement results from the three techniques. The network analyzer characterization technique is most widely used in practice due to its convenience, high sensitivity and high speed. The second acoustic phonon technique features non-invasive and package level testing, but it is still an indirect characterization method, like the network analyzer. In acoustic phonon detection, mechanical waves (phonons) generated by the actuated MEMS device are used as the coupling mechanism through which information on the dynamic mechanical state of the device can be obtained. The third stroboscopic SEM technique is capable of directly measuring the device motion, but its throughput is low and hence not suitable for high volume testing. The stroboscopic SEM imaging system is based on time-gated sampling of the analogue secondary electron (SE) signal. Unlike conventional SEM, stroboscopic SEM is able to detect the actual position of the structure at a specific point in time by taking a time-gated sample of the SEM SE signal at a specific phase of the structure's motion. © 2008 SPIE.