Broadband RF Interconnects in a Multi-Layer Advanced Packaging with a Si Interposer

This paper presents results obtained for multiple types of interconnects using a packaging technique for heterogeneous high-frequency (dc – 50 GHz) integration. The process has three organic dielectric layers laminated on each side of a central silicon interposer. The process allows for metalization of each dielectric layer, leading to 6 possible metal layers. A through-silicon coaxial via (TSV) using all available metal layers is designed. A back-to-back 50-Ω interconnect using two TSVs is measured and shows a return loss higher than 10 dB from dc to 50 GHz with an estimated insertion loss of 1 dB per TSV at 50 GHz. Measured results are compared to previously tested interconnect structures between different transmission lines in the same process.