Investigation on the material removal mechanism of polycrystalline gold film nanomilling

Nanostructures fabricated on metal films have found applications in biosensing, nanooptics, and nanoelectronics. Atomic force microscope (AFM) tip-based nanofabrication represents a promising approach for fabrication of nanostructures. However, the material removal mechanism and subsurface damage of polycrystalline gold during nanomilling remain poorly understood. In this study, we investigated the nanomilling mechanism of polycrystalline gold films through a combination of experimental analysis and molecular dynamics (MD) simulations. It has been observed that the material removal rate is influenced by the maximum undeformed chip thickness (UCT). Moreover, MD simulations demonstrate that grain boundaries inhibit dislocation nucleation and motion more effectively than in single-crystal materials. Complex dislocations and stacking faults are generated during nanomilling at high strain rates, leading to material embrittlement. Our findings deepen the understanding of material removal mechanism and elucidate the impact of grain boundaries on subsurface damage during nanomilling, offering valuable insights for fabrication of nanostructures on metal films.