The Efficient Parameter Extraction of Lossy Interconnect Lines by Accurate Characterization of Skin Effect in FEM

An exponential basis function (EBF) method is proposed for efficient and accurate electromagnetic modeling of lossy interconnect lines using the finite element method (FEM). In conventional FEM, dense volumetric meshes are required to resolve the skin effect in lossy conductors, which leads to high computational cost and limited accuracy. To address this challenge, the proposed method introduces EBFs featuring an attenuation factor aligned with the conductor thickness, thereby capturing the skin effect-induced current decay with fewer basis functions. Moreover, the volume current distribution is normalized to the surface current, which enables the conductor to be modeled solely with surface meshes and eliminates volumetric meshing inside conductors. In addition, the corresponding FEM matrix formulation is derived for face-mesh elements, thus integrating the method seamlessly into standard FEM workflows. Numerical results show that the proposed method achieves accuracy comparable to full 3D-FEM with coarser meshes, while outperforming impedance boundary methods in both accuracy and numerical stability.