A Simulation Study of a Bandpass Filter Formed by CNT-Core Cu-TSVs with Enhanced Thermal Management.

Bandpass filters based on through-silicon-via (TSV) interposers offer advantages such as compact footprint, excellent radio frequency (RF) performance, simplified processing, and low cost. However, as power densities in three-dimensional (3D) integrated circuits continue to rise, thermal management has become a critical performance bottleneck. In this work, we present a TSV-based bandpass filter design where the TSVs feature annular Cu conductors with carbon nanotube (CNT) cores. The annular Cu structure provides the required vertical electrical connectivity, while the high-thermal-conductivity CNT core facilitates inter-layer heat dissipation. RF simulations confirm that the RF characteristics of the filter remain comparable to those of filters based on conventional TSVs with Cu-pillar conductors or TSVs with annular Cu conductors and polymer cores such as benzocyclobutene (BCB). In addition, multiphysics simulations demonstrate that the proposed filter exhibits a maximum steady-state temperature of only 89.1 °C with a 5 W constant heat source attached to the interposer surface and a heat sink at the bottom side, presenting an efficient reduction compared to the other two types. The filter also shows reduced thermally induced surface deformation, confirming the thermal benefits of the CNT cores. Furthermore, comprehensive parametric analyses involving the influences of critical TSV structural parameters on the TSV-based capacitors and inductors are performed, providing guidelines for customized filter design. We believe the proposed design highlights a promising pathway for addressing the thermal management challenges in high-density RF integrated microsystems.