FRACTURE AND FATIGUE BEHAVIOR OF SINGLE-CRYSTAL SILICON MICROELEMENTSAND NANOSCOPIC AFM DAMAGE EVALUATION

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