Development of a Test Methodology to Determine Dynamic Fracture Strength in Microfabricated MEMS Structures

Abstract

As micro-electro-mechanical systems (MEMS) are becoming more and more common in both military and consumer electronics, virtual qualification of these devices remains an important design tool. To model MEMS devices subjected to high shock loading, the dynamic fracture strength of the most widely used MEMS material, single crystal silicon (SCSi), is needed. Minimal research has been performed to determine this material property and the research that has been completed suggests that fracture strength varies considerably with processing parameters. Therefore, an efficient and inexpensive testing method to determine the dynamic fracture strength of processed SCSi has been developed.

Experimentation with SCSi MEMS structures has also been carried out using this new testing method. A probabilistic Weibull distribution for bending of DRIE processed SCSi around the <110> directions was created as a design for reliability tool. Additional experiments demonstrated that the fracture strength for bending of DRIE processed SCSi around the <100> directions is greater than 1.1 GPa. Suggestions for subsequent work that focuses on the bending of SCSi around the <100> directions are also presented.