A High-Speed Design Methodology for Inductive Coupling Links in 3D-ICs

Inductive coupling links (ICLs) are gaining traction as an alternative to through silicon vias (TSVs) for 3D integration, promising high-bandwidth connectivity without the inflated fabrication costs associated with TSV-enabled processes. For power-efficient ICL design, optimisation of the utilised physical inductor geometries is essential, however typically necessitates the use of finite element analysis (FEA) in addition to manual parameter fitting, a process that can take several hours even for a single geometry. As a result, the generation of optimised inductor designs poses a significant challenge. In this paper, we address this challenge, presenting a CAD-tool for Optimisation of Inductive coupling Links for 3D-ICs (COIL-3D). COIL-3D uses a rapid solver based upon semi-empirical expressions to quickly and accurately characterise a given link, in conjunction with a high-speed refined optimisation flow to find optimal inductor geometries for use in ICL-based 3D-ICs. The proposed solver achieves an average accuracy within 9.1% of commercial FEA software tools, and the proposed optimisation flow reduces the search time by 26 orders of magnitude. This work unlocks new potential for power-efficient 3D integration using inductive coupling links.