Bias Temperature Instability of SiC Trench MOSFET under DC and AC gate stress

This study investigates the threshold voltage (V<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">th</inf>) instability and capacitance-voltage (C<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">g</inf>-V<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">g</inf>) degradation mechanisms in commercial SiC trench MOSFETs under DC and AC bias temperature instability (BTI) stresses. By analyzing ∆V<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">th</inf> and C<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">g</inf>-V<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">g</inf> characteristics under varying voltage biases, temperatures, and stress modes (DC, unipolar AC, and bipolar AC), distinct degradation is identified. High-bias DC BTI (e.g., 35 V) induces ∆V<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">th</inf> via Fowler-Nordheim tunneling at near-interface traps, aligning with conventional models. In contrast, bipolar AC stress (20 V/−10 V) triggers severe ∆V<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">th</inf> degradation (up to 5 V) and C<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">g</inf>-V<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">g</inf> drifts in both depletion and inversion regions at room temperature, which may attribute to bulk defect generation driven by recombination-enhanced defect reactions during polarity switching. Elevated temperatures (175°C) suppress AC-induced degradation, while unipolar AC stress shows opposite effects in ∆V<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">th</inf> degradation, highlighting the critical role of dynamic switching in defect kinetics. These findings reveal that AC BTI degradation stems from carrier recombination during rapid switching, fundamentally differing from the field-driven trapping mechanisms in DC BTI.