Investigation of the low-cycle fatigue mechanism for micron-scale monocrystalline silicon films

This study investigated the cyclic and static fatigue properties of 10 mu m thick, deep reactive ion etched, monocrystalline silicon films Stress life fatigue curves and fatigue degradation rates vs stress curves were generated at both 4 and 40 kHz, at 30 degrees C, 50% relative humidity (RH) A significant frequency effect was observed, with shorter fanatic lives and faster damage accumulation rates at 4 kHz Static fatigue was also observed with shorter static lifetimes at 80 degrees C, 90% RH than at 30 degrees C, 50% RH Fracture surface evaluation did not reveal any major difference between cyclically and statically fatigued devices These experimental results confirm that the fatigue of micron-scale silicon is not purely mechanical The study also proposes a fatigue scenario based on time-dependent subcritical crack growth to account for the low-cycle fatigue regime (C) 2010 Acta Materialia Inc Published by Elsevier Ltd All rights reserved