Non-equilibrium molecular dynamics of electromigration in aluminum and its alloys
With constant miniaturization of integrated circuits, the current densities experienced in interconnects in
electronic circuits has been multiplied. Aluminum, which is widely used as an interconnect material, has
fast diffusion kinetics under low temperatures. Unfortunately, the combination of high current density and
fast diffusion at low temperatures causes the circuit to fail by electromigration (EM), which is the mass
transport of atoms due to the momentum transfer between conducting electrons and diffusing atoms. In the
present study, the effect of alloying elements in aluminum on the diffusion behavior is investigated using a
non equilibrium molecular dynamics method (NEMD) under the effect of electromigration wind force.
The electromigration force was computed by the use of a pseudopotential method in which the force
depends on the imperfections on the lattice. 1.125 at% of various elements, namely Cu, Mg, Mn, Sn and
Ti were added into aluminum. The electromigration force was then calculated on the alloying elements
and the surrounding aluminum atoms and these forces incorporated into molecular dynamics using the
non-equilibrium formalism. The jump frequencies of aluminum in these systems were then computed. Cu,
Mn and Sn impurities were found to be very effective in lowering the kinetics of the diffusion under
electromigration conditions. Cu was known experimentally to have such an effect on aluminum for several
years, but the Mn and Sn elements are shown here for the first time that they can have a similar effect.
Fatih Gürçağ Şen
Non-equilibrium molecular dynamics of electromigration in aluminum and its alloys · 2006 · 110 sayfa.
Danışman: Doç.Dr. Mehmet Kadri Aydınol
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