A new layout method to improve the thermal stability of Multi-finger power HBT

A new layout method to improve the thermal stability of Multi-finger Power heterojunction bipolar transistors(HBT) is presented in this paper. In the new layout the through-wafer-via is inserted into the central of the Multi-finger Power HBT and the emitter fingers were connected by a wide metal layer that was exactly on the active thermal emitter area. According to the experimental results of a 8 fingers GaAs power HBT, the new layout method with compare to the routine layout method can reduce the thermal resistance from 242°C/W to 163°C/W and expand the thermal stability power density from 0.76 mW/µ m2 to 1.14 mW/µ m2. And also the radio frequency( RF) gain loss of the power HBT due to the thermal effect was suppressed with the improvement of the thermal stability. 1