Characterization of the Static Thermal Coupling Between Emitter Fingers of Bipolar Transistors

A strategy for compact modeling the static thermal coupling between the emitter fingers of SiGe heterojunction bipolar transistors (SiGe-HBTs) is described. An extraction methodology that includes the nonlinear temperature dependence of the thermal conductivity is introduced and applied to suitable test structures. The experimental results are used for calibrating a 3-D numerical solution of the equation for heat conduction based on a Green's function approach. The latter can then be employed for generating thermal coupling networks for arbitrary transistor configurations.