Cluster size and substrate temperature affecting thin film formation during copper cluster deposition on a Si (001) surface

The soft deposition of Cu clusters on a Si (001) surface was studied by molecular dynamics simulations. The embedded atom method, the Stillinger-Weber and the Lennar-Jones potentials were used to describe the interactions between the cluster atoms, between the substrate atoms, and between the cluster and the substrate atoms, respectively. The Cu sub(13), Cu sub(55), and Cu sub(147) clusters were investigated at different substrate temperatures. We found that the substrate temperature had a significant effect on the Cu sub(147) cluster. For smaller Cu sub(13) and Cu sub(55) clusters, the substrate temperature in the range of study appeared to have little effect on the mean center-of-mass height. The clusters showed better degrees of epitaxy at 800 K. With the same substrate temperature, the Cu sub(55) cluster demonstrated the highest degree of epitaxy, followed by Cu sub(147) and then Cu sub(13) clusters. In addition, the Cu sub(55) cluster showed the lowest mean center-of-mass height. These results suggested that the Cu sub(55) cluster is a better choice for the thin-film formation among the clusters considered. Our studies may provide insight into the formation of desired Cu thin films on a Si substrate.