Electro-thermal characterization of Si-Ge HBTs with pulse measurement and transient simulation

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.