Simulation of boron diffusion in Si and strained SiGe layers

Boron outdiffusion from the base into the emitter and collector caused by annealing in SiGe heterobipolar transistors (HBTs) has a serious influence on the transit frequency. One solution of the problem of boron outdiffusion is the creation of intrinsic spacers between the base, emitter and collector layers to prevent diffusion of boron across the heterointerface. For optimisation of SiGe HBT properties, several simulators are used. This paper presents a quantitative analysis of a SiGe HBT by process simulators SUPREM IV.GS and ISE TCAD-DIOS. Models for simulation of a boron-doped SiGe base of HBT are discussed and compared.