Mathematical approach and optimisation of nanometric base thickness for a SiGeC HBT dedicated to radiofrequency applications

We present, in this paper the mathematical approach for optimization nanometric thickness of the SiGeC base heterojunction bipolar transistors (HBTs), realized in BiCMOS industrial process. However, use of these components in applications microwave radio frequencies implores the use of complex structures shrinking. The base SiGeC is the active part of the transistor, the optimization of the nanometric thickness is a crucial aspect in order to accurately predict the characteristics of the component. Numerical approach modeling is investigated, using our 2D simulator SIBIDIF , based on the drift-Diffusion Model (DDM). It solves the continuity equations for electrons and holes, coupled with the Poisson’s equation, based on the concept of the finite difference mesh using a revised SchafetterGummel type approach and solved numerically with the Gauss Seidel’s method and matrix algebra. Simulation results obtained in this study are efficiently compared with electrical characteristics obtained by measurements. KeywordsNumerical modeling; SiGe(C); Base; HBT; BiCMOS; Nanometric thickness.