Transferred-substrate heterojunction bipolar transistor integrated circuit technology

Using substrate transfer processes, we have fabricated heterojunction bipolar transistors with 0.4 μm emitter-base and collector-base junctions, minimizing RC parasitics and increasing f_max to 820 GHz, the highest yet reported for a transistor. The process provides microstrip interconnects on a low-ε_τ polymer dielectric with a electroplated copper ground plane and substrate. Substrate thermal resistance is reduced 5:1 over InP. Important wiring parasitics, including wiring capacitance, ground via inductance, and IC-package ground-return inductance, are substantially reduced. Demonstrated ICs include lumped and distributed amplifiers with bandwidths to 85 GHz, master-slave flip-flops operable at over 48 GHz, and 50 GHz AGC/limiting amplifiers. Current efforts include further improvement in bandwidth, development of power devices, and demonstration of more complex mixed-signal ICs