Application of microscopic interferometry techniques in the MEMS field

Microscopic homodyne interferometry with monochromatic or white light illumination is up to now the most widely used technique for micromechanical devices and MEMS surface profiling. In the last five years its capabilities have been largely extended and this technique can now be applied to out-of-plane or in-plane vibration measurements, to micromechanical testing, to transparent film thickness mapping and to surface spectral reflectivity, mapping. In this paper we will review the performances and limits of this technique and its various applications in the MEMS field from technology assessment up to final device characterisation. Some guidelines are provided to achieve high frequency vibration measurements, transient response measurements as well as on wafer or in vacuum measurements. Finally, future developments needed are discussed.