Design and Fabrication of 2.5D Cryogenic Interposer With Integrated Superconducting TSVs and Resonators

A transmission line with TSVs was fabricated and characterized at room temperature and 10 mK. The extracted average loss per TSV is ~ 0.4 dB at 10mK within 4-6 GHz. That means TSVs can be used to carry microwave signals between the different chip surfaces in our future superconducting quantum processor. The frequency shift Δf <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">r</inf> for dense TSV resonator chip is much larger than for sparse TSV chip, which creates a method to optimize the resonator frequency.