Electrical Analysis and Modeling of 3D Through-Strata-Vias (TSVs) and Pads

Through-strata-via (TSV) is one of the most attractive3D integration solutions in that it offers a massive number of short interstrata connects, high data bandwidth, reduced delay and power consumption, small footprint, improved yield, heterogeneous integration and reduced volume-production cost. This work attempts to investigate the TSV signal integrity and, particularly, compares the performance among different TSV and pad combinations. Transient analysis, eye diagram and bathtub curves show a good behavior of TSV signal integrity in the time domain. Regarding to frequency response, the set of circular TSV and circular pad offers a slightly better performance than other shapes. When a misalignment is so large that the TSV does not land completely within the pad, the TSV frequency response is affected considerably. A big pad size degrades performance and decreases trace density, while a thinner pad would enhance process throughput and reduce cost. Simulation results also indicate that rather than using multiple small TSVs connecting to a common pad, it is better to implement one single big TSV because of less parasitics and coupling. Furthermore, the TSV component is carefully modeled, and the results from electromagnetic simulation and a broadband SPICE model are in a very good agreement.