THE INFLUENCE OF DIFFUSION PROCESSES ON THE SURFACE SELF-ORGANIZATION IN THE MULTILAYER FILM COATING

The multilayer film coatings are widely used in the electronic and optoelectronic industries. However, the technology of devices manufacturing requires that the number of defects should be kept to a minimum, otherwise, their operational properties will be poor. In recent years, it is assumed that the main cause of formation of defects within the film coatings is the formation of film surface relief. Surface roughness can be formed both during its depositing and post-heat treatment and during other phase transformations. The modeling of the process of thin-film coating surface self-organization will allow a better understanding of this phenomenon. The paper considers the 2D model of a solid body with a multilayer film coating. A small perturbation of film surface form is described by an arbitrary periodic function. Based on Gibbs thermodynamic approach, the authors got the evolutionary equation of film surface in combined action of surface diffusion determined by the derivative of chemical potential along the surface and the lattice diffusion associated with the stress alteration along the curved surface and capillary effect. Based on the initial approximation of perturbation method, the authors carried out the numerical analysis of morphological stability of flat form of multilayer film coating surface when affecting it with diffusion processes. The initial perturbation wavelength, the relative elasticity modules of the film system materials, the proportion of surface and lattice diffusion in the mass-transfer process, and the residual stresses were considered the key parameters of the task. The important feature of the study is that, by taking into account the lattice diffusion, the authors analyzed the influence of stress operator. It is proved that when increasing the lattice diffusion proportion, the relief is smoothed in case of tensions. For the compression forces, the lattice diffusion, as well as the surface diffusion, is the destabilizing process.