Transport models and advanced numerical simulation of silicon-germanium heterojunction bipolar transistors

Applications in the emerging high-frequency markets for millimeter wave applications more and more use SiGe components for cost reasons. To support the technology effort, a reliable TCAD platform is required. The main issue in the simulation of scaled devices is related to the limitations of the physical models used to describe charge carrier transport. Inherent approximations in the HD formalism are discussed over different technology nodes, providing for the first time a complete survey of HD models capability and restrictions with scaling for simulation of SiGe HBTs. Moreover, a complete set of models for transport parameters of SiGe HBTs is reported, including low-field mobility, energy relaxation time, saturation velocity, high-field mobility and effective density of state. Implementation in a commercial device simulator is drawn and findings are compared with simulation results obtained using a standard set of models and with trustworthy results (i.e. MC and SHE simulation results and experimental data), validating proposed models and clarifying their reliability and accuracy over different technologies. Finally, electrical breakdown phenomena in SiGe HBTs are analyzed: a novel complete model for multiplication factor is reported and validated by experimental results; new M model provides an exhaustive accuracy over a wide range of collector voltages.