Authors: A. Barbato, M. Rondanini and C. Cavallotti
Affilation: Politecnico di Milano, Italy
Pages: 540 - 543
Keywords: Monte Carlo, density functional theory, CVD, silicon
Growth rates and morphology of thin solid films deposited through Chemical Vapor Deposition processes are strongly dependent on chemical-physical events that occur at time and length scales differing by several orders of magnitudes. Models adopted to study these complicated systems are usually focused on describing what happens on a single length scale. For example, ab initio calculations are often used to evaluate rates of elementary gas phase and surface reactions, which can then be inserted in rector models and used to simulate the growth process. Generally, reactors models aimed at predicting film growth rates describe surface events fitting adsorption rates to experimental parameters or, if a surface kinetic scheme is used, imposing that the concentration of surface species is at the steady state. In such models the effect of surface morphology on film growth rate is usually neglected. In this work we show that the morphology of the growing film can have a significant impact on film growth rates affecting the surface reactivity. We base such conclusion on simulations of Si epitaxial deposition we performed using a multiscale CVD model in which we couple consistently the gas phase fluid dynamics to the surface morphological evolution, with kinetic constants of some key surface reactions determined from first principles.