Broadband Characterization of Co-planar GSG Wirebonds for RF Heterogeneous 2.5D Integration

With the advancement in silicon interposer teehnol- ogy and Through Silicon Vias (TSVs) [1], [2], heterogeneous 2.5D integration at mm-wave frequencies is becoming more approachable than ever. In this work, we investigated co-planer Ground- Signal-Ground (GSG) wirebonds as cost-effective interconnect for RF 2.5D applications. On-silicon GSG wirebonds of 25μm diameter and 100μm pitch were realized and measured at different lengths and at frequencies up to 40 GHz. Circuit modeling of the measurements showed excellent agreement. Additionally, GSG wirebonds with lengths below 500μm achieved insertion loss below 2dB up to 40GHz, while still leaving room for improvements, e.g., by reducing bond pitch or deploying ribbon bonds.