Abstract: In this paper microscopic interferometry is used for 2D and 3D profiling of micromechanical devices deformation and, is extended to allow vibration spectra measurements on a few microns wide microdevices. This is obtained by adding an apertured photomultiplier with suitable signal processing and subnanometric piezoelectric excitation. Resonant frequencies are detected both from vibrations-induced fringes contrast variations and by using a homemade wide bandwidth (10 MHz) double lock-in amplifier. This allows vibration measurements up to several MHz with a spatial resolution down to 1.25 micrometer and a detection limit of vibrations amplitudes in the 0.2 - 1 nm range. Furthermore the system allows a direct visualization of the whole vibration modes and can be applied for automated bulge testing of membranes. System operation for 3D profilometry, vibrometry and bulge testing is demonstrated on Cr cantilever microbeams and microbridges fabricated by surface micromachining and on membranes. Capabilities of the system for large vibration amplitudes measurements and its extension for on-wafer resonant frequencies measurements by using optical excitation are discussed. !20
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