A scalable model for temperature dependent thermal resistance of SiGe HBTs

This paper presents a geometry scalable approach for temperature dependent thermal resistance (R
_TH
) calculations in trench-isolated SiGe heterojunction bipolar transistors (HBTs). The model is able to predict the RTH at any temperature and power dissipation (P
_diss
). The temperature dependency is obtained by discretizing the heat flow region into n-number of elementary slices depending on the temperature gradient. RTHs of each slice are calculated using temperature dependent thermal conductivity. The results are compared to 3D thermal TCAD simulations for a wide range of ambient temperature (T
_amb
), P
_diss
and device dimensions. Finally, the scalability is validated through measurements of several transistor geometries as well as two different technologies and found to be in good agreement.