Two-Dimensional Numerical Modeling of Sub Micrometer SiGe HBT Transistors

This paper presents an investigation of numerical modeling of SiGe HBT (Silicon-Germanium heterojunction Bipolar Transistor). For this, we consider three models: the so called Drift Diffusion Model (DDM), the Isothermal Energy Balance model (EB) and the Non-Isothermal Energy Balance model (NEB). The considered devices correspond to the BiCMOS6G 0.35 mu m industrial processes and are dedicated to radiofrequency applications. The numerical device modeling considers Technology CAD (TCAD) simulation. The DDM model describes the classical transport in semiconductor devices. The energy balance model describes the energy transport. This model is coupled with thermionic emission transport. The NEB model permits to take into account the non-uniform distribution of the carrier's temperature. Some typical numerical results are presented such as the current-tension curve, Gummel curves and cutoff frequency for the three models. For submicron devices, it is clear that it is necessary to take into account the phenomena such as thermionic emission and the non-uniform distribution of the carriers.