113-GHz f_T graded-base SiGe HBTs

Abstract

A novel low-thermal cyclc proccss was used to fabricatc epitaxial SiGe-base heterojunction bipolar transistors (HBTs) with record unity current gain cutoff frequencies. The process includes an in situ phosphorus-dopcd polysilicon emitter which requires only a 800°C-10s anneal. A peak f <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">T</sub> of 113 GHz at V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">CB</sub> of 1V was obtained for an intrinsic base sheet resistance of 7 kΩ/square.