Ultra-broadband chip-to-chip interconnects to 220 GHz for Si-based millimeter-wave systems

Ultra-broadband chip-to-chip interconnects at high frequencies are demonstrated. These interconnects, based on the Quilt Packaging (QP) approach, appear to be promising for applications in millimeter-wave circuits due to their extremely wide bandwidth and ease of assembly. The performance of chip-to-chip interconnects in a 50 Ω coplanar waveguide environment on high-resistivity silicon substrates has been measured to 220 GHz using a vector network analyzer, and is compared with projections obtained from 3D electromagnetic modeling. Single-mode, resonance-free operation is demonstrated through 220 GHz, with insertion loss below 1.5 dB over the full frequency range. Although the resistance of the conductive epoxy (used for the prototypes reported here) limits the performance of the QP nodules, simulations indicate that better joining methods such as soldering promise to yield insertion loss of much less than 1 dB at 220 GHz.