Fully Dry-etched InP Double-Hetero Bipolar Transistors with ft > 400 GHz
26 June 2006
Indium Phosphide-based Double-Heterostructure Bipolar Transistors have high potential for analog, digital, and mixed-signal applications requiring extreme clock speed and high voltage swing. To harness the full performance of the InGaAs/InP material system, the HBTs need to be scaled to submicron dimensions. Yield has always been an issue with wet-etch defined submicron InP HBTs. More complex circuits require homogeneous and reproducible processing techniques. We demonstrate a manufacturable InP HBT technology which relies on dry etching of all three semiconductor mesas (emitter, base, and subcollector), thus greatly improving control of critical dimensions and device parameters such as Cbc Cbe, and collector current at which maximum ft and fmax are attained. Further, we replaced the traditional emitter metal liftoff patterning process by dry-etched refractory metal.
