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Stress reduction behavior in metal-incorporated amorphous carbon films: first-principles approach Abstract. The stress reduction behavior in metal-incorporated amorphous carbon films was investigated by the first-principle calculation. We calculated the total energy of the system with changes in bond angles between the incorporated metal (Ti, Mo, Cr, W, Ag, Au, Al, Si, etc) and the carbon atoms by using DMOL 3 computational software package. The four carbon atoms are arranged as a tetrahedron, with a carbon or metal atom at the center. The total energy increased substantially as the bond angle deviated from the equilibrium value when a carbon atom is located at the tetrahedron center. However, with a replacement by a metal atom at the center of the tetrahedron, the increase in the total energy due to the distortion in bond angle was significantly reduced. The pivotal action of the metal atoms dissolved in the carbon matrix would be more significant when noble metals having filled d-shells are incorporated compared to the transition metals having unfilled d-shells. These atoms have a weak and more isotropic bond with carbon atoms as confirmed by the electron density distribution.

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As the existence of charged clusters in the gas phase, which were predicted by the charged cluster model, has been confirmed for many thin film processes, it becomes important to understand the deposition dynamics of the clusters. In this study, deposition behaviors of the cluster of 1985 Au atoms on the (100) gold surface were studied at the deposition temperatures of 300, 700 and 1000 K by molecular dynamics (MD) simulation using the embedded atom method (EAM) potential. After 320 picoseconds of cluster landing on the surface at 300 and 700 K, only a part of the cluster rearranged into the epitaxial orientation with the substrate with the rest of the cluster making a grain boundary at 300 K and a twin at 700 K. At 1000 K, however, the cluster fully underwent epitaxial recrystallization. These results imply that the high rate of epitaxial deposition by clusters of a few nanometers is possible as long as the substrate temperature is sufficiently high as was previously suggested in the charged cluster model.

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