Manufacturable Low-Cost Flip-Chip Mounting Technology for 300–500-GHz Assemblies

We developed a chip mounting technology suitable for low-cost assemblies in the 300-500-GHz frequency range, compatible with standard chip and submount fabrication techniques. The waveguide and transition designs are compatible with indium phosphide heterobipolar transistor millimeterwave monolithic integrated circuit chip architecture. Increased conductor shielding in different multilayer thin-film waveguide topologies is applied to suppress radiative losses, enabling lowloss interconnects up to 500-GHz bandwidth. Standard flipchip align-and-place equipment is used to assemble the chips onto submounts. Losses are evaluated by banded S-parameter measurements between 10 MHz and 500 GHz. For an optimized stripline-to-stripline transition, an insertion loss of less than 1 dB was measured at 500 GHz.