Multiscale Modeling of Stress-Mediated Diffusion in Silicon - Ab Initio to Continuum

摘要

The introduction of new "back-end" materials, as well as the further scaling of silicon device dimensions, has raised the level of stress in device structures. Current engineering simulations of diffusion neglect the direct effect of stress on diffusivity. In this paper, we demonstrate for the first time the development of a complete methodology to simulate the effects of general anisotropic non-uniform stress on diffusion of B in Si. The macroscopic diffusion equation is derived from microscopic transition state theory, relating the diffusivity to the microscopic jump parameters. The required microscopic parameters are calculated from first principles. Stress in gate stack materials is measured as a function of temperature and used to develop a stress-prediction methodology. All these numbers are implemented into a continuum model and used to examine diffusion in a complex stress field.