An Online Gate Oxide Degradation Monitoring Method for SiC MOSFETs Based on Turn-ON Gate Current Change Rate

Gate oxide degradation (GOD) presents a reliability issue for silicon carbide (SiC) metal-oxide-semiconductor fieldeffect transistors (MOSFETs), especially under high-temperature and high-electric-field conditions. This letter proposes an online condition monitoring (CM) method based on the peak value of the turn-on gate current change rate (di<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">g</sub>/dt<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">,max</sub>). The technique utilizes a non-invasive PCB Rogowski coil to measure dig/dt,max, demonstrating high practicality. Accelerated aging tests under positive and negative high-temperature gate bias (HTGB) and hightemperature gate switching (HTGS) conditions reveal correlations between di<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">g</sub>/dt<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">,max</sub> and GOD, with variations of 5.61%, 5% and 8.33%, after 160 hours of aging. Double pulse test (DPT) results indicate that dig/dt,max is independent of external factors such as temperature, drain-source voltage (V<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">ds</sub>), drain current (I<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">ds</sub>) and package aging. Results from a buck converter further validate the feasibility of long-term online monitoring.