Resonant-type micro-probe for vertical profiler

We present a characterization method, which is dedicated to the measurement of the inner dimensions of high aspect ratio micro-holes, typically 100mum in diameter and 1mm in depth. Micro-probes with an integrated force-sensitive element are manufactured in silicon technology. Vertical surface profiles can be obtained through the measurement of the deflection at the end of a cantilever beam due to contact force, while scanning over the inner surface of the hole. Two alternative solutions have been developed for force sensing. The first one is based on piezoresistive detection and the other one is based on frequency shift of mechanical resonators. In this paper, the latter sensing method is presented more in detail. The operation principle, modeling and fabrication process are presented.