3-D Electrothermal Modeling of SiC Multichip Power Modules for a More Accurate Reliability Assessment

This paper shows a 3-D electro-thermal FEM-based modeling of SiC multichip power modules including the volume heat generation of SiC power MOSFET dies. Based on a newly developed measurement approach and a physics-based semiconductor modeling, the on-state resistance components of a power MOSFET are extracted and used to distinguish the surface from the volume heat generation. The results show that the temperature-dependent on-state resistance components of high-voltage (>1.2 kV) SiC power MOSFETs have a significant impact on the temperature-distribution within a SiC power MOSFET die. The modeling error is increasing with thickness and, hence, the breakdown voltage capability of the devices when using only the surface heat generation in the ET FEM modeling for predicting the die temperature of HV SiC power MOSFETs. Furthermore, a difference between thermal-only and ET simulations is observed in terms of not only the average/maximum temperature but also the surface temperature distribution.