Measurement and modeling of thermal resistance of high speed SiGe heterojunction bipolar transistors

Thermal resistance has been measured for high speed SiGe HBTs with various emitter widths and lengths. The smaller devices exhibited higher thermal resistance values, but eventually resulted in lower junction temperature rise for a given power density. A physical model has been developed which showed good agreement with the measurements. The model indicates that the thermal resistance depends strongly on the deep trench geometry. The thermal resistance is also anticipated to increase with the existence of adjacent devices due to a heat dissipation interference, according to the model.