Origin and evolution of a crack in silicon induced by a single grain grinding

Abstract

A brittle material fails under fracture due to the initiation and propagation of a crack. A high performance device will suffer catastrophic failure under brittle fracture. Nevertheless, the knowledge of a crack on silicon (Si) is limited to microscale, and the origin and evolution of a crack in a single crystal Si have not been reported. In this study, a median crack was ground by a developed diamond tool with a tip radius of 780 nm and a speed of 40.2 m/s. Molecular dynamics (MD) simulations reveal that a funnel-shaped structure is formed during nanocutting, consisting of a median crack and an amorphous phase including two discontinuous crystallites, which is in good agreement with those of experiments. A crack initiates and propagates in Si under hydrostatic stress at 12 GPa approximately. The material removal is through shear during nanocutting at a ductile mode on the surface, which is different from extrusion reported in previous nanocutting of Si. These findings provide new insights on the origin and evolution of a crack in a brittle material, which is beneficial to avoid catastrophic fracture and keep the stability, reliability and longevity of a brittle solid based high performance device.