Thermal analysis of the via holes in AlGaN/GaN HEMTs

This paper presents the comparison of the highest channel temperature of two different layouts-the individual source vias (ISV) and the mircostrip transmission line (MSL). The number of substrate vias and the dimension of metal electrode in layout are different for these two structures, which cause different thermal resistance and thermal capacitance. Considering the reality, it is reasonable to add the boundary conditions: air convection and the heat-sink convection. Thus more accurate channel temperature is obtained, which make a big difference on device reliability and is necessary for both physical model and equivalent circuit model. Variation trend of the thermal resistance at different temperature and different size of via holes are also analyzed. The results show that via holes have great influences on the thermal resistance and thermal capacitance.