A Nano-Cantilever Bending Method for Interface Cracking in Nanoscale Materials

Abstract

A nanocantilever bending method is developed to investigate the interface cracking in multilayered nanoscale materials basing on the technology of the focused ion beam (FIB) and the transmission electron microscopy (TEM). With FIB, a nanocantilever specimen consisting of 20-nm-thick copper (Cu) layer and 500-nm-thick silicon nitride (SiN) layer on a silicon (Si) substrate is fabricated from a macroscale multi-layered material (Si/Cu/SiN) with the proposed method. By using a minute loading apparatus, the loading experiment is conducted in TEM, and the crack initiation at the edge of Cu/Si interface in different specimens is in situ observed. The critical stress fields at crack initiation are analyzed with the finite element method, and both normal and shear stresses concentrate at the region of 100 nm from the interface edge in all specimens. In addition, the normal stress is much larger than the shear one. A close observation on stress fields shows that the normal stress field at the area 20 nm–30 nm away from interface edge produces the local criterion for crack initiation at the edge of Cu/Si interface in nanoscale components.