Low-Loss Air-Isolated Through-Silicon Vias for Silicon Interposers

An air-isolated through-silicon via (TSV) technique is proposed to reduce radio-frequency (RF) losses in silicon interposers. A testbed containing air-isolated and conventional TSVs is fabricated and characterized from 10 MHz to 20 GHz with an L-2L de-embedding technique. The proposed air-isolated TSV technique yields 46.7% lower insertion loss compared to conventional TSVs at 20 GHz from 3-D full-wave simulations and measurements. Moreover, the impact of the air-isolation region width between TSVs on capacitance and conductance is quantified.