Reliability of anchors at surface micromachined devices in shock environments

This paper presents a methodology to determine the fracture strength of surface micromachined anchors. First, fracture tests at micro-scale specimens of different anchor size have been performed by a macro-scale load system. Then this fracture data was evaluated statistically applying the Weibull distribution function. It turned out that the statistical theory of brittle material fracture is not completely valid for the applied fabrication technology, as the determined Weibull parameters show a dependency on the anchor size and are therefore not material parameters. Nevertheless, the obtained results can be applied for reliability statements at final MEMS products based on the determined fracture forces and fracture stress.