Three‐dimensional molecular dynamics simulation of behaviors of a void in an Al interconnection under high current stress has been accomplished employing empirical two‐body potential and the Huntington‐Grone ballistic model for an electron wind force. Stability of a void under a uniform strain field was first investigated; it was shown that a void was stable under a tensile strain, while it was unstable under a compressive strain. Then, a void movement into cathode direction was clearly demonstrated in the single‐crystalline Al interconnection at the high current density of 1 × 1010 A/cm2. The activation energy of the drift velocity of the void was 0.76 eV. Next, behaviors of a void in [111] bicrystal grains with a periodic boundary condition which resembled a bamboo structure interconnection was investigated. A void was stabilized at the grain boundary at low current density conditions; however, it could go across the grain boundary and move further to the cathode direction when the current density was high enough. It was shown that when a void comes close to the grain boundary, it suddenly annihilates into vacancies and rapid movement of vacancies into the grain boundary occur. A void was formed again at the grain boundary. This model will explain the void annihilation phenomena, reported by the in situ scanning electron microscope (SEM) observations. After stopping the current, a backflow of a void was observed as a consequence of the strain energy relaxation when the current density was high. These obtained results explained well the experimental observations qualitatively; furthermore, new predictions were obtained with quantitative analysis based on total potential energy analysis.
Kagamiy ama I-4-l,Hi gas hi-Hiros him a, 7 24, JAPAN Stabilities and movements due to electromigration of a void in an Al lattice or in a bicrystal grain boundary are investigated by thrree-dimensional molecular dynamics simulations empioying ttre empirical pairpotential and the ballistic model for an electron wind force. It is shown ttrat a void becomes more stable when a grain boundary energy increases. A void movement toward cathode direction, which is in good agreement with experiments, is simulated when a void is in the latice. However, the drift velocity of the void is significantly retarded when the void come close to the grain boundary. This may be due to the stabilaization effect of the grain boundary on the void.
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