Two-dimensional process simulation of bipolar devices using a multilayer simulator: IMPACT4

A new 2D multilayer process simulator specially developed for the study of advanced bipolar technologies is described. Numerical problems are presented and an application is introduced to demonstrate the possibilities of the program. The layer management is performed by the topology simulation module, according to the etching or deposition steps. The well-known string model is used and special algorithmic problems have been solved in order to take into account the general multilayer aspect. The compatibility with mesh generation has been also carefully studied: to avoid accuracy loss in the surface shape definition, the string model points are also the surface vertices of the FEM triangulation