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Modeling of Heteroepitaxial Thin Film Growth by Kinetic Monte Carlo

Innovative thin film technology has enabled the development of finer electronic devices, but a greater understanding of the atomic level process of film growth and its relationship with film characterization is needed to successfully manufacture these devices. Kinetic Monte Carlo (KMC) simulations can treat phenomena with a µs order time scale in thin film growth. Most of the previous KMC simulations were conducted on a film surface that consisted of identical atoms with incident particles, that is homoepitaxial growth. In this study, KMC parameters that define heteroepitaxial growth are characterized by a simple Lennard-Jones type two-body interaction. KMC simulations were then performed until dislocations were created. KMC parameters, activation energy and attempt frequency, were shifted by the expansion and contraction of atomic bonds at the heteroepitaxial surface. The amount of the shift depended on the distance from the interface, but they saturated at more than three deposited layers. Thus, the KMC simulation of heteroepitaxial growth can be conducted using only a few sets of KMC parameter tables that are adopted according to the layer. The layer dependence of the KMC parameters for the Ni/Cu interface was also investigated using the embedded-atom (EAM) potential as the interatomic interaction for describing realistic materials. KMC simulations of Cu film growth on a Ni(111) surface was conducted and compared with homoepitaxial Cu film growth on Cu(111). The activation energies of diffusions around an island on the heteroepitaxial surface decreased more than those on the homoepitaxial surface. Thus, the shape of the island for the heteroepitaxial growth of Cu on Ni(111) was more simplified than the homoepitaxial growth of Cu on Cu(111).