For present-day micro-electronic designs, it is becoming ever more important to accurately model substrate coupling ef-fects. Basically, either a Finite Element Method (FEM) or a Boundary Element Method (BEM) can be used. The FEM is the most versatile and flexible whereas the BEM is faster, but requires a stratified, layout-independent doping profile for the substrate. Thus, the BEM is unable to properly model any specific, layout-dependent doping patterns that are usually present in the top layers of the substrate, such as channel stop layers. This paper describes a way to in-corporate these doping patterns into our substrate model by combining a BEM for the stratified doping profiles with a 2D FEM for the top-level, layout-dependent doping pat-terns, thereby achieving improved flexibility compared to BEM and improved speed compared to FEM. The method has been implemented in the SPACE layout to circuit ex-tractor and it has been successfully verified with two other tools.

In mixed-signal designs, substrate noise originating from the digital part can seriously influence the functionality of the analog part. As such, accurately modeling the properties of the substrate as a noise-propagator is becoming ever more important. A model can be obtained through the Finite Element Method (FEM) or the Boundary Element Method (BEM). The FEM performs a full 3D discretization of the substrate, which makes this method very accurate and flexible but also slow. The BEM only discretizes the contact areas on the boundary of the substrate, which makes it less flexible, but significantly faster. A combination between BEM and FEM can be efficient when we need flexibility and speed at the same time. This paper briefly describes the BEM and the FEM and their combination, but mainly concentrates on the theoretical validation of the combined method and the experimental verification through implementation in the SPACE layout to circuit extractor and comparison with commercial BEM and FEM tools.