Bias temperature instability and junction temperature measurement using electrical parameters in SiC power MOSFETs

Junction temperature sensing is an integral part of both on-line and off-line condition monitoring where direct access the bare die surface is not available. Given a defined power input, the junction temperature enables the estimation of the junction-to-case thermal resistance, which is a key indicator of packaging failure mechanisms like solder voiding and cracks. The use of temperature sensitive electrical parameters has widely been proposed as a means of junction temperature sensing however, there are certain challenges regarding their use in SiC MOSFETs. Bias Temperature Instability from charge trapping in the gate dielectric causes threshold voltage drift, which in SiC affects some of the key temperature sensitive electrical parameters including ON-state resistance, body diode forward voltage as well as the current commutation rate. This paper reviews the impact of bias temperature instability on the accurate junction temperature measurement using temperature sensitive electrical parameters in SiC MOSFETs