Simulation of nucleation and growth stages for sputtered films

摘要

A three-dimensional simulation system of sputter deposition for microstructure evolution of thin films has been developed in this study. In terms of the nucleation stage, the nucleation process is modeled using a randomization method, which produces atomic data to describe the condition of nuclei coverage. In terms of the growth stage, the topographic evolution is modeled using level set methods, and the deposition rate is evaluated considering shadow effects. The effects of controlled nucleation variables (including sticking coefficients, captured radii of clusters and critical nuclei size) on nucleation types are discussed in the model as well as the influences of nucleation types on the following grain growth. The simulation results show that three different nucleation types (networks, flat pieces and islands) are observed for different combinations of controlled nucleation variables. Under the assumption of immobile grain boundaries, the resulting grain shapes and grain structures of these three nucleation types are different. The simulation results of nucleation and growth are also shown to be consistent with the experimental data of references.