Effect of silicon surface orientation on the Au droplet motion

Abstract

The Monte Carlo simulation results of the gold droplet motion along the silicon surface during the gold deposition are presented in this paper. The droplet behavior on silicon substrates with (111), (011) and (311) orientations at temperatures above the eutectic temperature of the Au-Si system was considered. The reason for the droplet movement is the substrate dissolution by the liquid droplet in an attempt to maintain the equilibrium Au-Si melt concentration. It was demonstrated that the gold droplet movement in 〈110〉 directions is determined by the etch pit asymmetry under the droplet, which depends on the substrate orientation. On the Si(111) surface the etch pit shape is symmetric. In this case, the droplet moves only along the vicinal surface, where the vicinal steps provide the lateral droplet-crystal interface asymmetry. The average droplet velocity on the vicinal Si(111) surface increases with an increase in the misorientation angle. On Si(011) and Si(311) surfaces the lateral droplet-crystal interface is asymmetric. A lower droplet velocity on the Si(311) surface, compared to the Si(011) surface, is due to a different etch pit shape under the droplet for these surface orientations.