Online Monitoring for Threshold Voltage of SiC MOSFET Considering the Coupling Impact on BTI and Junction Temperature

Abstract

Gate oxide degradation can reduce the reliability of silicon carbide metal-oxide-semiconductor field-effect transistor (SiC MOSFET), which is indicated by bias temperature instability (BTI). BTI-induced threshold voltage ( V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">\text th</sub> ) shift has an effect on ON-resistance ( R <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">\text DS - ON</sub> ) and leakage current. Meanwhile, the rising junction temperature ( T <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">j</sub> ) caused by power losses will affect V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">\text th</sub> . It is of vital significance to the reliability research provided that V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">\text th</sub> shift can be rapidly monitored when the coupling impact on BTI and T <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">j</sub> is sufficiently considered. In this article, the body effect in SiC MOSFET and its impact on the body diode voltage ( V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">\text SD</sub> ) are analyzed, and the temperature dependence of V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">\text SD</sub> is investigated. In addition, the impact mechanism of BTI in SiC MOSFET on V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">\text SD</sub> is studied. Finally, a method for online monitoring V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">\text th</sub> shift due to BTI and T <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">j</sub> is proposed employing the forward voltage of the SiC MOSFET body diode under body effect at low measuring current. Through the proposed method, V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">\text th</sub> shift can be indirectly evaluated using V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">\text SD</sub> . Most importantly, considering the impact of T <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">j</sub> , this methodology can be used in different working conditions, and the problem of difficult extraction of V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">\text th</sub> is solved under complex working conditions.