Identification of fatigue crack extension process in zero-tension cyclic stress test of polysilicon films

This paper presents evidence for a fatigue crack extension process in zero-tension cyclic stress test of polysilicon film specimens with notches. Initial cracks and their fatigue extension were found on the fracture surfaces observed in a scanning electron microscope. The fatigue crack extension process was quantitatively analyzed in detail using Paris´ law on the basis of the parameters evaluated from static and fatigue test data. The observed and estimated crack lengths are consistent with each other. The results suggest that the fatigue crack extend into the silicon itself.