Low-Loss Air-Cavity Through-Silicon Vias (TSVs) for High Speed Three-Dimensional Integrated Circuits (3-D ICs)

Since the coupling loss of conventional low resistivity silicon (LRSi) is considerable in high speed three-dimensional integrated circuits (3-D ICs), air-cavity through-silicon vias (TSVs) on LRSi are proposed in this letter to reduce the conductive substrate losses for microwave applications. The
$Q$
-factor and insertion loss are exploited to assess the effect of air-cavity TSVs. The accurate wideband equivalent circuit model and simplified
$\pi$
-model are derived based on the physical design parameters, which are established by the ADS software. Well agreements between the proposed models and 3-D full-wave EM field simulation of Ansoft's HFSS are shown with the operating frequencies up to 20 GHz.