Electrical-Thermal Characterization of Through Packaging Vias in Glass Interposer

Low-cost thin glass is developed as a promising material to advanced interposers for high density electrical interconnection in 2.5-D and three-dimensional (3-D) integration. In this paper, the electrical-thermal performance of through glass vias is investigated. The distributed transmission lines model for tapered through glass vias (T-TGVs) in signal-ground-signal type differential structure is first established and validated against the 3-D full-wave electromagnetic simulator. The model is applicable to TGVs made of carbon nanotubes(CNTs) by incorporating CNT quantum and kinetic effects. Using the proposed model, the impact of various parameters on the electrical characteristics of the differential T-TGVs is investigated. It is observed that the inductive element of conductor loss plays a significant role on the electrical performance, which makes the CNT-TGV interconnects show unique electrical characterization that totally different from its through silicon vias (TSVs) counterpart. For example, the signal loss of TGV interconnects in different-mode signaling is even lower than that in common-mode and increasing via pitch increases signal loss. Furthermore, the thermal performance of 2.5-D integration with TGVs is investigated with COMSOL multiphysics. It is shown that TGV is a primary path for heat dissipation and increasing TGV distribution density can significantly lower the peak temperature of 2.5-D integration. Because of high thermal conductivity of CNTs, glass interposer with CNT-TGVs can achieve better thermal performance in comparison to its Cu counterpart.