Online Monitoring for Threshold Voltage of SiC MOSFET Considering the Coupling Impact on BTI and Junction Temperature
Jinlei Xin, Mingxing Du, Ziwei Ouyang, Kexin Wei
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.