High-cycle fatigue test of nanoscale Si and SiO2 wires based on AFM technique

This paper focuses on revealing the effects of specimen size, frequency and temperature on fatigue lives of nanoscale single crystal silicon (SC-Si) and silicon dioxide NOD wires for reliable design of micro/nano electro-mechanical systems (MEMS/NEMS). Evaluation of fatigue lives for nanoscale fixed-fixed SC-Si and SiO₂ wires was performed by stress-controlled cyclic bending tests under an atomic force microscope (AFM) at temperatures ranging from 295 K to 573 K. In MEMS-00 and MEMS-01, the quasi-static bending tests under the AFM for nanoscale SC-Si wires were reported, which discussed the effect of specimen size on elastic/plastic deformation behavior of the wires at intermediate temperatures. Here, we exhibit high-cycle fatigue lives of nanoscale SC-Si and SiO₂ specimens. The specimen size produced a large effect on fatigue life, but frequency and temperature dependences were not observed. The 200 nm-wide SC-Si wires had the fatigue lives of 10¹-10² times longer than those for 550 nm-wide wires at the same stress level. This research newly proposes fatigue life criteria for nanoscale SC-Si and SiO₂ specimens using a power law.