Effects of temperature and grain size on diffusivity of aluminium: electromigration experiment and molecular dynamic simulation

Abstract

Understanding the atomic diffusion features in metallic material is significant to explain the diffusion-controlled physical processes. In this paper, using electromigration experiments and molecular dynamic (MD) simulations, we investigate the effects of grain size and temperature on the self-diffusion of polycrystalline aluminum (Al). The mass transport due to electromigration are accelerated by increasing temperature and decreasing grain size. Magnitudes of effective diffusivity (Deff) and grain boundary diffusivity (DGBs) are experimentally determined, in which the Deff changes as a function of grain size and temperature, but DGBs is independent of the grain size, only affected by the temperature. Moreover, MD simulations of atomic diffusion in polycrystalline Al demonstrate those observations from experiments. Based on MD results, the Arrhenius equation of DGBs and empirical formula of the thickness of grain boundaries at various temperatures are obtained. In total, Deff and DGBs obtained in the present study agree with literature results, and a comprehensive result of diffusivities related to the grain size is presented.

Effect of Thermomigration on Electromigration in SWEAT Structures

“…The electron wind force, attributed to the momentum exchange between conducting electrons and metal atoms, pushes atoms diffusing from cathode to anode. At the same time, the mass transport driven by temperature gradient, namely thermomigration (TM), is inevitably accompanied with EM [9][10][11].…”

Implementation of Fully Coupled Electromigration Theory in COMSOL

“…The driving force of electromigration is attributed to the momentum transfer between conducting electrons and diffusion metal atoms, which is vividly called the electron wind force. However, the intense electric currents in interconnects during electromigration are accompanied by the gradients of atomic concentration, mechanical stress, and temperature [6][7][8][9][10]. These gradients become the driving forces of mass transport coupled with electron wind force.…”