Theoretical Modeling of the Morphological Evolution of Thin Films During Deposition Processes

In the modern nanotechnology, thin films deposition is one of the fundamental and general techniques to manufacture the nano-materials or nano-devices. The objective of this study is to develop a self-consistent phase-field model to simulate the formation and evolution of thin films during a deposition process. In this study, the microstructural evolution of thin-films was represented by the temporal field variables related to the concentration of the adatoms, which could also reflect the effects of the thermodynamics and kinetics. Various critical factors, such as the interfacial energies between different phases, and the deposition rates of adatoms on the film and substrate, were included in the theoretical model and their influences were further investigated via the numerical simulations. We delivered a comprehensive analysis of the surface morphologies and structures formed in the deposition processing, and indicated the underlying mechanism led to the formation of featured profiles. From the simulation results, it proved that the nucleation and growth of thin films were sensitive to the competitive processes between the deposition and diffusion. The formation of three-dimensional islands or layers on the substrate surface was in accordance with the Volmer-Weber, Frank-van der Merwe and Stranski-Krastanov modes of films growth under the corresponding conditions. This self-consistent model had revealed the general physics related to the growth mechanisms of thin films. In addition, it could also be implemented to predict the characters of thin films in various extreme situations.