MEMS inspection by Digital Holographic

We employed Digital Holographic Microscope (DHM) as a useful method for determining, with high accuracy, the MEMS out-of-plane deformations due to the residual stress introduced by fabrication process and to understand the effect of a thermal load on MEMS profile. The measured profiles can be employed for a quantitative estimation of the residual stresses by mean of some analytical and numerical models. Moreover, DHM also allows determination of variation of the profile of the object due to some external dynamic load (e.g. change in temperature, pressure, electrostatic). In this paper, MEMS behavior subjected to thermal load has been evaluated. In particular, the variation of profiles of cantilever beams subjected to a thermal treatment from 23°C to 130°C has been measured.