Atomistic modeling of lattice frame effects on laser-induced dislocation behaviors in nanopore mending processes

Abstract

In recent years, the femtosecond laser technique has 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 is still not well understood so far. In this paper, the microscopic dislocation behaviors of the lattice mending of metallic nanopore defects induced by femtosecond laser is presented using a modified continuum-atomistic modeling approach and the quantitative dislocation-based analysis. Two different cases of lattice frame effects are elaborated to characterize the dislocation behaviors and the nanopore mending mechanisms. The lattice frame is 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 is observed to form a prismaticlike 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 are 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 causes a rapid mending of the hole with a metastable lattice structure. The heterogeneous reaction dynamics of dislocation nucleation on the pore defect surface is analyzed in detail in this study. The photomechanical and thermally-activated plastic flow of mending processes is also clearly elucidated. The results provide vital insights into better dynamic behavior characterization of how the ultrafast laser interacts with metallic microdefects.