Threshold Voltage Monitoring Method for SiC MOSFET Based on Body Diode Voltage under Body Effect

Threshold voltage (V TH ) shift caused by bias temperature instability (BTI) has become the most serious reliability problems in silicon carbide (SiC) metal-oxide-semiconductor field-effect transistor (MOSFET). BTI-induced V TH shift is divided into recoverable shift and permanent shift. The traditional V TH shift measurement method for silicon (Si) devices is difficult to monitor the recoverable shift of SiC MOSFET. To solve this problem, firstly, based on the physical structure and working principle of SiC MOSFET, this paper establishes an analytical model of forward voltage of body diode (V SD ) under body effect based on the reverse conduction resistance (R SD-ON ). Secondly, the influence mechanism of BTI on V SD is studied. Finally, a method is proposed to monitor V TH of SiC MOSFET utilizing the forward voltage of body diode under body effect at small current. The experimental results prove that this method can real-time extract V TH , and the monitoring method is simple.