Multi-Layer Polymer-on-Si Interconnects for Heterogeneous Integration to 50-GHz

This paper presents a variety of broadband, low-loss interconnects designed on an experimental process that includes 6 organic resin-filled dielectric layers laminated on both sides of a silicon interposer. The process allows metallization of each dielectric layer, making 6 metallic layers available for design. This paper highlights 3 interconnects using 3 metal layers, as well as a coaxial through-silicon via (TSV) interconnect using all 6 layers. Interconnects on both high-resistivity and low-resistivity interposer wafers are characterized from 2 to 50 GHz, showing a return loss better than 10 dB and insertion loss below 0.5 dB across the frequency range for organic-layer interconnects. The TSV transitions demonstrate 0.11 dB/mm and 0.16 dB/mm insertion loss at 10 GHz when fabricated on high and low resistivity interposers, respectively. Broadside couplers are designed and characterized to evaluate cross-coupling between lines on different metal layers. A second generation wafer including multilayer passive circuits is fabricated and measured. Results for a 6-dB grounded coplanar waveguide coupler and a substrate-integrated waveguide multi-layer filter are presented.