Microstructure evolution during the early stages of deposition: Monte Carlo simulations

Thin film growth morphology during the early stages of deposition is investigated with Monte Carlo simulations using a solid-on-solid (SOS) model. The simulator incorporates the surface atomic processes of deposition and surface migration of adatoms. Thus, this work deals with atomic deposition processes which are often called physical vapor deposition processes. Deposition is assumed to be a random process with surface relaxation to a nearest neighbor stable site. Surface migration is modeled as a nearest neighbor hopping process. The model allows for the interlayer transport.; Simulation results for the case of submonolayer homoepitaxy of Fe yields good quantitative agreement with experiments and scaling rules. Simulation results obtained using effective pair-bond model parameters indicate that thermal dissociation of singly and doubly coordinated atoms is not negligible at the highest temperature studied in homoepitaxy of Fe. Simulations used to investigate the growth front when a few monolayers are deposited predict a step-edge barrier of 0.1 eV for Fe/Fe. Simulations for Ni on Cu suggest that the increase in surface roughness observed experimentally for coverages greater than 6 ML is due to a change in the step-edge barrier as a result of strain energy due to small lattice mismatch between Ni and Cu.; The microstructural evolution of Ag grown on GaAs(110) surfaces is monitored using nm spatial resolution secondary electron microscopy. In the initial stages of growth, the films grown at room temperature consist of isotropic 3D Ag islands, while depositions at 250{dollar}spcirc{dollar}C resulted in islands elongated along the {dollar}langle{dollar}110{dollar}rangle{dollar} direction. Monte Carlo simulation results indicate that anisotropy in the surface diffusion and adatom attachment along the {dollar}langle{dollar}100{dollar}rangle{dollar} and {dollar}langle{dollar}110{dollar}rangle{dollar} directions are the main factors for the elongation of islands at 250{dollar}spcirc{dollar}C deposition temperature.; This SOS model is used to study nucleation inside idealized rectangular trenches as might be present on a patterned wafer. The island density decreases along the wall from top to bottom and increases along the base from corner to center, corresponding to the spatial dependence of flux. The nucleation density is smallest at the bottom corner on the wall side as compared to the base side, which again corresponds to a jump in flux at corners. As the aspect ratio increases the difference in nucleation density at the base corner and center decreases. The nucleation density decreases at any position inside the trench as the aspect ratio is increases.