Application of an Innovative Method for the Fatigue Characterisation of 15 mm Thick Epitaxial Polysilicon

The present work deals with the application of a new method for the on-chip fatigue characterization of micro electromechanical systems. The method is based on the fact that the 2 nd harmonic of comb actuated system is proportional to the driving velocity; thus an indirect monitoring of the system displacement is possible and the sample breaking can be registered by electrical measurements. The method has been applied for characterising the industrial material used by STMicroelectronics: a 15 ?m thick epitaxial polysilicon and the experimental results have been compared to the literature data. In particular, the computed relative strength reduction to the cycles to failure follow the same trend derived in different loading conditions of frequency, thus confirming a not time depending failure mechanism. © 2006 IEEE.