CONTROLLING THE MORPHOLOGY OF CVD FILMS

The morphology of the gas-solid interface during typical chemical vapo r deposition (CVD) processes is investigated. The dynamic behavior of the interface depends on many factors, including local curvature of th e film, reactant diffusion, adsorption equilibrium, surface kinetics, and mobility of adatoms. These factors depend on material properties o f the system and reactor conditions, such as the deposition temperatur e and pressure. A 2-D model proposed describes the evolution of the in terface in Cartesian coordinates under the influence of stabilizing an d destabilizing effects. A linear stability analysis is used to predic t under which conditions a planar interface becomes unstable. Stabilit y criteria of a simplified 1-D analysis is not necessarily valid if th e real system has more than one dimension. The substrate temperature a nd reactor pressure are important factors affecting the stability of f ilm growth and thus the morphology of CVD films. An increase in temper ature stabilizes planar film growth if the deposition is diffusion-lim ited, but destabilizes it if the process is reaction-controlled. The r eactor pressure has a destabilizing effect on planar film growth durin g a typical CVD process.