Challenges of Junction Temperature Calibration of SiC MOSFETs for Power Cycling - a Dynamic Approach

For thermal impedance measurement (Zth) and power cycle testing (PCT) of semiconductor power packages, a precise measurement of the junction temperature is essential and critical for lifetime characterization. Based on recent observations on advanced silicon carbide (SiC) MOSFETs from several manufacturers, it has been observed that the commonly used static temperature calibration method might lead to a significant calculation error of the virtual junction temperature Tvj. This study investigates the time-dependent transient response of the body diode's forward voltage under test conditions with a switched gate bias applied. Based on the results, a new approach of the measurement of Tvj is proposed. This dynamic calibration method is applied to address the transient effects detected in Zth and PCT. Further investigations into the potential influence of additional test parameters on the transient behavior as well as a comprehensive comparison of SiC MOSFETs from different semiconductor manufacturers are the subject of the investigations.