FEDSS—Finite-element diffusion-simulation system

The FEDSS program simulates semiconductor processes in two dimensions. An accurate model of the diffusion of impurity atoms into a substrate is necessary to assess the effects of process changes on impurity profiles. The process steps to be modeled include ion implantation, oxidation/drive-in, chemical predeposition through the surface, and oxide deposition. The finite-element method transforms the diffusion equation for impurity atoms to a simulation model at a discrete number of points. Direct techniques are used to solve the resulting matrix equations. The impurity distributions resulting from sequences of the process steps are shown.