Electromagnetic analysis for interconnect structures with inhomogeneous substrates

Electromagnetic (EM) analysis for interconnect and packaging structures usually relies on the solutions of surface integral equations (SIEs) with an assumption of homogeneous substrates in integral equation solvers. In this work, we consider the inhomogeneity of substrates and replace the SIEs with the volume integral equations (VIEs) to form volume-surface integral equations (VSIEs) for the structures. The VSIEs are solved by the method of moments (MoM) with the Rao-Wilton-Glisson (RWG) and Schaubert-Wilton-Glisson (SWG) basis functions and could be more versatile for inhomogeneous problems. A numerical example is presented to demonstrate the effectiveness of the approach.