Improved thermal stability of power SiGe heterojunction bipolar transistor with novel emitter structure

A novel segmented emitter structure with nonuniform finger length and spacing has been presented to alleviate adverse thermal effects in multi-finger SiGe HBT power device. Considering the various thermal resistances of different components for the segmented multi-finger HBT, an appropriate thermal model is developed. Using this model, the thermal simulation for a ten-finger power SiGe HBT with segmented emitter structure is performed and the three-dimensional temperature distribution on emitter fingers is obtained. Compared with traditional emitter structure, the maximum junction temperature reduce significantly from 416.3 K to 405 K, the thermal resistance reduce from 154.67 K/W to 140 K/W, thus the thermal stability of improved structure is enhanced apparently.