The simulation of source and drain domain build-up in modern MOSFETs is an explictly three-dimensional TCAD problem due to several effects. First there are silicon/silicon-dioxide, silicon/polysilicon and polysilicon/silicon dioxide interfaces whith a specific structure in each spatial dimension. Segregation effect take place at these interfaces and influence formation of the junction through the pile-up phenomena. Furthermore, the silicon/silicon-nitride and silicon/silicon-dioxide interfaces are places of point defect generation and annihilation. These interface processes have stronger impact on the point defect dynamics than bulk processes and thus influence considerably the diffusion behavior of the dopants. Here again the three-dimensional structure of the interfaces between silicon and others materials of the MOSFET structure is the cause of three-dimensional dopant profiles broadening.
In the following sections we present three-dimensional simulation results. The simulations are carried out with the FEDOS tool based on the diffusion models and PDE discretization and linearization schemes presented in previous sections.