Low-loss coplanar waveguides interconnects on low-resistivity silicon substrate

This paper describes fabrication, characterization and simulation of low-loss coplanar waveguide (CPW) interconnects on low-resistivity silicon substrate. The fabrication of CPWs is low-temperature (below 250°C) and incorporates a spin-on low-k dielectric benzocyclobutene (BCB) and self-aligned electroplating of copper. The performance of CPWs is evaluated by high-frequency characterization and EM simulation. CPWs with different line width (W) and line spacing (S) are investigated and compared. Using a BCB layer as thick as 20 μm, CPW fabricated on a low-resistivity silicon substrate exhibits an insertion loss of 3 dB/cm at 30 GHz.