A>400 GHz fmax transferred-substrate heterojunction bipolar transistor IC technology

We report transferred-substrate AlInAs/GaInAs bipolar transistors. A device having a 0.6 μm×25 μm emitter and a 0.8 μm×29 μm collector exhibited f/sub /spl tau//=134 GHz and f
_max
>400 GHz. A device with a 0.6 μm×25 μm emitter and a 1.8 μm×29 μm collector exhibited 400 GHz f
_max
164 GHz f/sub /spl tau//. The improvement in f
_max
over previous transferred-substrate HBT's is due to improved base Ohmic contacts, narrower emitter-base and collector-base junction areas, and slightly reduced transit times. The transferred-substrate fabrication process provides electroplated gold thermal vias for transistor heat-sinking and a microstrip wiring environment on a low dielectric constant polymer substrate.