Effects of film thickness on critical crack tip opening displacement in single-crystalline and polycrystalline submicron Cu films

摘要

We performed in-situ field emission scanning electron microscopy fracture toughness tests on single-crystalline and polycrystalline submicron-thick Cu films. In all specimens, the notch root became blunt, and a crack was initiated from the blunted notch root. The critical crack tip opening displacement (CTOD) for crack initiation, delta(i), was thickness dependent, where di decreased with a decrease in the thickness. The critical CTOD normalized by the thickness, delta(i)/B, values of the films were similar (delta(i)/B = 1.4-1.9), irrespective of the film thickness and microstructure. This suggested that the local fractures of the submicron Cu films were similar. (C) 2016 Elsevier Ltd. All rights reserved.