InP HBT Integrated Circuit Technology for Terahertz Frequencies

We report on the development of a 0.25 μm InP HBT technology suitable for integrated circuit demonstrations at the lower end of the THz frequency band (0.3-3THz). Transistors demonstrate an extrapolated f
_max
of >800 GHz while maintaining a common-emitter breakdown voltage (BV
_CEO
) >4 V. The transistors have been integrated in a full IC process that includes three-levels of interconnects, backside wafer thinning to 50 μm with a through-wafer via process, and a backside etch singulation process that allows for the formation of free-standing integrated waveguide probes. The technology has been utilized to demonstrate amplifiers, fixed-frequency and voltage controlled oscillators and dynamic frequency dividers all operating at >300 GHz.