Test Methodologies for Dynamic Fracture Strength of Single Crystal Silicon

Abstract

Single crystal silicon (SCSi) is the primary component for many microelectromechanical systems (MEMS). Therefore, identification of the dynamic fracture strength of SCSi can tremendously aid in virtual qualification of new MEMS devices used in dynamic loading applications. Unfortunately, the fracture strength is influenced by surface flaws, which are functions of microfabrication processing techniques. This work assesses the influence of deep reactive ion etching (DRIE) technology on the dynamic fracture strength of SCSi. The primary focus was to develop test methodologies that can be used for identifying the dynamic fracture strength of SCSi. The methodologies developed were applied to simple MEMS shock test structures to measure preliminary dynamic fracture strength values. Based on the experiments performed thus far, the dynamic fracture strength of DRIE processed (100) SCSi is >1.10 GPa and <1.37 GPa for bending around <100> and <110> directions, respectively. A statistically significant number of tests will be performed in the near future for verifying these fracture strength values and quantifying the uncertainties. Finally, recommendations are provided for the planned future experiments.