ABSTRACT
This chapter investigates through-silicon via (TSV)’s tapering effect, an inevitable by-product of the nonideal dry reactive ion etching–based manufacturing, and its impact on TSV’s electrical performance and reliability properties. For TSV’s electrical performance, we show that TSV delay (estimated by the Elmore delay model) is not bidirectionally symmetric for a tapered TSV. Then we study several reliability properties of tapered TSV such as its current density and thermal mechanical stress distribution, TSV’s self-heating effect, and its electromigration trend. We show that the current density and thermal mechanical stress distributions inside the TSV are more nonuniform in realistic tapered TSVs than ideal cylindrical TSVs, both of which lead to faster material fatigue and severe electromigration. Based on current, stress, and thermal simulation, we build a multiphysics simulation framework to quantify TSV’s electromigration trend, which is capable of estimating TSV’s electromigration lifetime. From this electromigration simulation framework, we can easily recognize the most vulnerable positions in a 3D structure, which would be valuable during TSV manufacturing and design optimization.
