Design space exploration of Through Silicon Vias for high-speed, low loss vertical links

In this paper, performance analysis of Through Silicon Vias (TSVs) considering various bonding techniques is investigated. In that, bonding of TSVs using Cu-Sn microbumps, Cu-Ag microbumps and Cu-Cu direct bonding is considered. We present SPICE-compatible equivalent circuits for these configurations using exhaustive simulations performed on electromagnetic field solver, Ansys Q3D. We analyze these TSV configurations for various interconnect performance metrics, such as delay, energy delay product, energy per bit, insertion loss and bandwidth density. Our analysis gives physical insights into the effect of microbumps/discontinuities on the TSV performance. Our analytical results show that vertical interconnects using Cu-Cu direct bonding significantly outperforms those using Cu-Ag or Cu-Sn microbumps, which makes it an excellent candidate for high-speed, low loss vertical links.