Analysis of Signal Propagation Through TSVs Within Distilled Water for Liquid-Cooled Microsystems

This paper analyzes the impact of liquid cooling on the electrical characteristics of through-silicon vias (TSVs) using a microfluidic cooling testbed containing TSVs. The microfabrication of TSVs in a silicon micropin-fin heat sink is presented, and the high-frequency characterization of TSVs within a micropin-fin heat sink using distilled water is performed from 10 MHz to 20 GHz. TSV capacitance and conductance are extracted from measurements; TSVs within distilled water have larger capacitance and conductance than TSVs in silicon due to the lossy characteristics of distilled water at high frequencies. A coaxial-like TSV configuration, which consists of multiple ground TSVs surrounding a center signal TSV, is proposed and demonstrated to shield signal TSVs from the coolant.