用于改善多指SiGe HBT热特性的变指间距设计方法研究

A Novel Method of Emitter Finger Spacing Design to Improve Thermal Characteristic of Multi-Finger SiGe HBT

通过引入表示发射指之间热耦合程度的耦合热阻,建立了多指异质结双极晶体管(HBT)热阻模型。基于该模型,得到了耦合热阻与指间距的变化关系,并用于器件指间距的设计。当耦合热阻均匀分布时,所对应的一套非等值的指间距值便是器件温度均匀分布所要求的指间距值。用该方法得到热阻分布与热模拟得到的温度分布相吻合。但这种方法不必通过热模拟来得到温度分布均匀的SiGe HBT各指问距值,具有快速、直观的优点,为变指间距的设计提供了方便。

The thermal resistance model of multi-finger Heterojunction Bipolar Transistor（HBT） is established by introducing coupling thermal resistance which represents thermal interaction among fingers. Based on the model, the dependence of coupling thermal resistance on finger spacing is obtained, which is used to obtain a set of unequal value finger spacings. When coupling thermal resistance profile is uniform, there is a set of finger spacing values which are coorespodingly in need of the temperature uniform distribution for HBT. The thermal resistance profile obtained by this method is in agreement with temperature distribution from thermal simulation method. But, this method avoids repeated thermal simulation to obtain a set of finger spacings for uniform temperature distribution HBT,which is more fast and much easier to be observed. It provides convenience for finger spacing design.