Theta-like specimen to determine tensile strength at the micro scale

Micro- and nano-electromechanical systems are typically formed via lithographic and etching processes that leave residual surface features, stresses, and chemistry that ultimately control component strength and thus device and system reliability. Here, we describe a new test specimen for micro-scale tensile strength measurements that allows for direct assessment of surface effects on strength. Specimens were formed from silicon-on-insulator wafers by deep reactive ion etching and tested with instrumented indentation. The experimental results were interpreted using finite element analyses to extract fracture strength. Fracture strengths as great as 3 GPa were observed, with fracture initiating at processing-induced flaws and propagating along {111} and {110} planes.