A silicon platform with Through-silicon vias for heterogeneous RF 3D modules

This paper presents a silicon platform with Through-silicon vias (TSV) interconnects for Radio-Frequency applications, implemented in a via-last integration scheme. As it is aimed at transmitting a wide range of signals, it is mandatory to accurately evaluate frequency dependent loss of TSV. To achieve attractive RF performances, the silicon platform is carried out on High-Resistivity (HR) substrates. Indeed, silicon conductivity is a material property that has major influence on TSV electrical characteristics. Fabrication, design and characterization of wideband wave-guided TSV transition are detailed. Measurements and three-dimensional electromagnetic (3D EM) simulations demonstrate significant influence of parasitic coupling through the substrate. Finally, technological and design optimizations are highlighted to reduce impedance mismatch and substrate influence.