Simulation of sputtering from liquid Cu targets

Abstract

The sputtering of Cu atoms from liquid targets by normally incident 5 keV Ar^+ ions was simulated using the multiple interaction molecular dynamics technique. Yields, energy distributions, and angular distributions of sputtered atoms were obtained at several temperatures slightly above and below the experimental melting point of copper. In all cases the resulting angular distributions of ejected atoms peaked more sharply than the cos θ behavior predicted by linear cascade theory. The ratio of yields from individual layers of the liquid targets, and the energy and angular distributions of ejected atoms generally were found to be similar to those obtained in previous simulations with solid Cu targets. Our results also are in qualitative agreement with Dumke's measurements of angular distributions and layer yield ratios of sputtered atoms from liquid Ga-In eutectic alloy targets. In particular, no marked changes in yields or energy distributions were observed when the temperature of the target was lowered below the nominal melting point of copper. The angular distributions were found to broaden with increasing temperature.