In recent years, the femtosecond laser technique had emerged as an effective tool for defect mending, especially for fault repairs of the conducting wire in three-dimensional integrated circuits. However, the nanodefect mending mechanism subjected to photothermal and mechanical stress introduced by ultrafast laser dynamics was still not well understood so far. In this paper, the microscopic dislocation behaviours of the lattice mending of metallic nanopore defects induced by femtosecond laser was presented using a modified continuum-atomistic modelling approach and the quantitative dislocation-based analysis. Two different cases of lattice frame effects were elaborated to characterize the dislocation behaviours and the nanopore mending mechanisms. The lattice frame was found to possess a direct effect on controlling the mechanisms of nucleation and growth of dislocation during laser interaction with metallic microdefects. The nanopore defect with a symmetric lattice frame was observed to form a prismatic-like slip structure around the pore region, and the dislocation loop consequently expands along its glide-prism plane. The growth of the loops continues even after they were fully mended to form sessile junctions by creating a local anisotropic hardening structure. On the other hand, the nanopore defect of an asymmetric lattice frame induces drastically irregular lattice glides, forming a tight network of junction loops around the mended area. It was found that the fast shock wave enhanced by the stress concentration factor around the pore that enabled a cooperative movement of sheets of atoms around the pore. This particular mechanism caused a rapid mending of the hole with a metastable lattice structure. The heterogeneous reaction dynamics of dislocation nucleation on the pore defect surface was analyzed in detail in this study. The photomechanical and thermally-activated plastic flow of mending processes was also clearly elucidated. The results provided vital insights into better dynamic behaviour characterization of how the ultrafast laser interacts with metallic microdefects.

Atomistic Modeling of Lattice Frame Effects on Laser-Induced Dislocation Behaviors in Nanopore Mending Processes. P.H.Huang, H.Y.Lai: Journal of Applied Physics, 2010, 108[12], 123504