Kinetic Monte Carlo simulations of stress and morphology evolution in polycrystalline thin films

Abstract

Kinetic Monte Carlo simulations have been used to model the evolution of the morphology and the stress in a polycrystalline film. Stress is incorporated into the simulation by considering the processes that occur at the grain boundary as the film grows, in the same way that has been used for analytical models. A section of a grain is simulated by assuming the grain boundary can act as a sink and a source for atoms on the surface; the relative rates of diffusion into and out of the boundary depend on the surface kinetics and the stress. This approach allows the complex interaction between the film growth kinetics, surface morphology evolution, and stress to be investigated. For a decreasing growth rate, the growth mode changes from being dominated by nucleation of new clusters to step-flow. This affects the flux of atoms into the grain boundary and makes the corresponding stress more compressive. The effect of growth interrupts and a barrier to interlayer diffusion are also investigated.