Non-Equilibrium Molecular Dynamics Simulation of Electromigration in Aluminum-Based Metallic Interconnects

The effect of alloying elements in aluminum on diffusion behavior was investigated using non-equilibrium molecular dynamics (NEMD) under the effect of electromigration wind force. The electromigration wind force was computed based on a theory using the pseudopotential formalism of the elements, where it depends on the type and distribution of the imperfections in the lattice. It was found that the electromigration force on the impurity depends on the scattering power of the atom, which is related to the chemical valence. Elements like Cu, Li and Na gave low values, but the incorporation of such forces into molecular dynamics simulations underline the importance of the electromigration force distribution on the host aluminum atoms. In this regard, in NEMD formalism, we calculated the atomic jump frequency of aluminum atoms in alloys containing different impurity elements like Cu, Mg, Mn, Na, Sn and Ti. It was found that the electromigra-tion diffusion process slowed down considerably, compared to pure Al, in alloys containing elements having a softer Al-M pair potential, namely Cu, Mn and Sn