Molecular Dynamics Simulation of Electromigration in Nano-sized Metal Lines

Abstract

The molecular dynamics simulation of electromigration has been made for nano-sized metal lines. By solving Laplace equations for the electric field using the relaxation method the current direction and the local current density were determined. In this model, a two-dimensional Lennard-Jones single crystal structure in contact with an insulator was first assumed. The periodic boundary conditions of both the current and atomic flows were setup in the direction of the applied voltage. The forces originated from atomic pair potential and electric field were setup to atoms in the molecular dynamics simulation. The simulations showed that the generations of vacancies, their movements and disappearances could be realized at the areas with a large current density. When the current direction was along the closest packing direction of atoms, the diffusion coefficient became largest. Results suggest an existence of thresholds of the voltage and temperature for the metal line lifetime.