Fracture and fatigue behavior of single crystal silicon microelements and nanoscopic AFM damage evaluation

Abstract

Quasi-static bending and fatigue tests of single-crystal silicon microelements fabricated by photoetching were performed. The microelements were subjected to simple bending and three-point bending with two-support roll length of 1.5 mm. The tests were conducted by using a specially designed electromagnetic actuator based testing machine (load range: 0.1 mN–5 N, accuracy: 0.02 mN), which enables mechanical testing including fatigue of microelements. Mechanical testing including fatigue of microelements could be performed with sufficient precision. Single-crystal silicon microelements deformed elastically until final catastrophic failure, showing a brittle nature. The influence of specimen size on quasi-static fracture behavior was investigated: fracture strength increased with a decrease in sample width, and the maximum fracture strength reached 7.7 GPa. The influence of water on fatigue strength was discussed. The fracture surface and sample surface were examined using an atomic force microscope. Nanoscopic damage during testing was evaluated, and the fracture mechanisms were discussed.