  This paper describes a new and simple approach to accurately characterize the
transient self-heating effect in Si-Ge Heterojunction Bipolar Transistors
(HBTs), based on pulse measurements and verified through transient
electro-thermal simulations. The measurements have been carried out over pulses
applied at Base and Collector terminals simultaneously and the time response of
Collector current increase due to self-heating effect are obtained. Compared to
previous approach, a complete calibration has been performed including all the
passive elements such as coaxial cables, connectors and bias network.
Furthermore, time domain junction temperature variations, current of heat flux
and lattice temperature distribution have been obtained numerically by means of
3D electro-thermal device simulations. The thermal parameters extracted from
measurements using HiCuM HBT compact model have been verified with the
parameters extracted from electro-thermal transient simulation. It has been
shown that, the standard R-C thermal network is not sufficient to accurately
model the thermal spreading behavior and therefore a recursive network has been
employed which is more physical and suitable for transient electro-thermal
modeling.
