Short Circuit Capability and Short Circuit Induced $V_{\mathrm{TH}}$ Instability of a 1.2-kV SiC Power MOSFET

Abstract

The withstand capability and threshold voltage (VTH) instability of 1.2-kV silicon carbide (SiC) MOSFETs under repetitive short circuit (SC) tests are investigated. An SC test system is constructed to apply repetitive SC stress to SiC MOSFETs and measure the transfer I-V characteristics and gate-to-source leakage current (I <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">GSS</sub> ) after each set of SC tests. To evaluate the SC capability, repetitive SC tests with different SC durations (t <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">p</sub> ) are conducted until device failure. The SC withstand time (SCWT) at 1000 SC cycles is found to be ~3.3 μs. V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">TH</sub> instability under repetitive SC tests prior to the device failure is characterized. A bidirectional V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">TH</sub> shift behavior, i.e., negative shift at shorter t <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">p</sub> and positive shift at longer t <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">p</sub> , was revealed. The V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">TH</sub> shifts under repetitive SC tests are attributed to the SC pulse process according to the results of high-temperature reverse bias (HTRB) and dynamic high-temperature gate bias (HTGB) tests. The underlying mechanisms of the complex V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">TH</sub> shift behavior are explained in a unified framework by taking into account the junction temperature (T <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">j</sub> ) increase with longer t <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">p</sub> . TCAD device simulation is used to help analyze the mechanisms.