Interatomic Potentials In FCC Metals And Molecular Dynamic Simulation Of Z-shaped Copper Nanobelt

Presently, the dimension of interconnects in Integration Circuits has been reduced to a nanometer scale, and materials are apt to undergo a structural transformation under such tiny size by the effect of temperatures and mechanical stress. We adopt molecular dynamics (MD) simulation to investigate the structural transformation of a miniaturized Z-shaped model of practical copper interconnects.A key factor in MD simulation is the accuracy of interatomic potentials. As face-centered-cubic (FCC) metals are widely applied in interconnects, various potentials are summarized in this research to obtain an explicit image about MD method. Besides classical pairwise potentials such as Lennard-Jones potential and Morse potential, embedded atom method (EAM) becomes a primary choice in many potential styles for its perfect application in FCC metals. Johnson analytic EAM combines the virtues of a concise expression and efficient calculations. Fitting tremendous experimental results and calculations from ab intio, the EAM presented by Mishin et al describes interatomic behaviors in FCC metals precisely.A research is conducted to study the structural transformation of Z-shaped copper nanobelt during a mechanical elongation by MD simulation. Continuous mechanical loading accumulates much stress in the two corners of the Z-shaped nanobelt, and the stress drives the dislocation atoms nucleating in the {111}planes. Propagation of dislocation atoms will dominate a slippage of a whole {111}plane. At 10.0K, in one corner of Z-shaped nanobelt, these slippages transform the initial < 100> orientation into < 111> and < 110> orientations, and in the other corner into all < 111> orientation, whereas the latter reorientation, induced by Lomer-Cottrell lock (L-C lock), is limited in a triangular region. When temperature ranges from 100.0K to 500.0K, there is a universal reorientation. Firstly, L-C lock emerges symmetrically in both corners of the nanobelt. Secondly, further elongation forms an atomic configuration of double L-C locks. At last, the double L-C locks are incorporated into a large-angle L-C lock. The simulating results also show the fact that the time of the dislocation emergence depends on temperatures strongly.