S. Spinner, M. Doelle, P. Ruther, I. Polian, O. Paul, B. Becker, University of Freiburg, Freiburg, Germany

Summary: We report an experimental test system which enables the automated analysis of mechanical stress impact on the reliability of microelectromechanical systems (MEMS). With this system, in-situ electrical characterization and optical inspection are performed while subjecting MEMS devices to defined mechanical loads. Impact objects of various geometries, e.g., contact probes or wafer prober needles, can be applied which are aligned relative to the MEMS device using an xyz-nanopositioning stage with a positioning accuracy of 20 nm. This positioning stage enables programmable static forces up to 3.6 N and dynamic loads at frequencies up to 20 Hz. With this highly flexible system reliability tests, postmanufacturing tests and stress screens can be performed on single chips as well as on whole wafers with diameters up to 6 inch. Preliminary results on long-term reliability tests using CMOS-based stress sensors exploiting the piezoresistive effect in field effect transistors are presented.