Compact Layout and Bias-Dependent Base-Resistance Modeling for Advanced SiGe HBTs

In this paper, an improved and extended set of physics-based analytical equations for describing the external and internal base resistance of silicon-germanium HBTs as a function of geometry (layout) is presented. The investigated layouts include single- and double-base contacts not only in parallel but also perpendicular to the emitter finger. In addition, via and slot base contacts, a large range of link to internal-base-sheet-resistance ratio, and changes in external base layout dimensions are covered. The new equations are verified using quasi-3-D device simulation and are demonstrated to be applicable to all practically useful emitter aspect ratios.