Book excerpt: This work presents a comprehensive theory describing atomic diffusion in silicon crystals under strong nonequilibrium conditions caused by ion implantation and interaction with the surface or other interfaces. A set of generalized equations that describe diffusion of impurity atoms and point defects are presented in a form suitable for solving numerically. Based on this theory, partial diffusion models are constructed, and the simulation of many doping processes used in microelectronics is carried out.Coupled Diffusion of Impurity Atoms and Point Defects in Silicon Crystals is a useful text for researchers, engineers, and advanced students in semiconductor physics, microelectronics, and nanoelectronics. It helps readers acquire a deep understanding of the physics of diffusion and demonstrates the practical application of the theoretical ideas formulated to find cheaper solutions in the course of manufacturing semiconductor devices and integrated microcircuits.