Direct Parameter Extraction Of Base and Emitter Resistances For SiGe HBTs Using DC Data Only

Abstract

A new method to directly extract base and emitter resistance parameters for SiGe HBTs using the Mextram bipolar compact transistor model has been presented. The method only requires a standard forward Gummel measurement and accounts for several second order effects like high-injection base conductivity modulation, Early effect and emitter current crowding. Base and emitter resistance parameters have been extracted over a wide temperature range (300K - 93K) for a first generation 0.5µm SiGe HBT with a peak cut-off frequency of 50 GHz at 300K. The HBT features a heavily doped poly-silicon emitter, an extrinsic base region doped well above the Mott's transition (3e18 cc for boron in silicon) and an intrinsic base region doped very close to the Mott's transition. The extracted parameters have been verified by comparison with several different methods.