Crosstalk attenuation with ground plane structures in three-dimensionally integrated mixed signal systems

We report significant crosstalk reduction between two transistor planes in 3D integrated circuits (3D ICs) using tungsten ground plane structures as the isolation layer. Simulation and experimental results show ∼8 dB of crosstalk attenuation. A significant conclusion of our study is that a ground plane that physically shadows the region it is isolating is optimum for deriving most of the benefits of isolation. We also show that for ground planes composed of standard MOS metallizations, i.e. W, Al, Cu, similar crosstalk isolation is expected. The inter-device ground plane structures have potential to be standard isolation technology for 3D mixed-signal and RF integrated systems due to simple fabrication and significant crosstalk attenuation.