An In-Depth Investigation Into Short-Circuit Failure Mechanisms of State-of-the-Art 1200 V Double Trench SiC MOSFETs
Xuan Li, Yifan Wu, Zhao Qi, Zhen Fu, Yanning Chen, Wenmin Zhang, Quan Zhang, Hanqing Zhao, Xiaochuan Deng, Bo Zhang
Abstract
In this article, the short-circuit capability of 1200 V state-of-the-art silicon carbide (SiC) metal–oxide–semiconductor field-effect transistor (<sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">mosfet</small>) featuring reinforced double <underline xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">t</u>rench structure (named RDT-MOS) is investigated comprehensively, involving the maximum short-circuit time and energy under various dc bus voltages and gate driving voltages. Furthermore, the corresponding failure mechanisms of RDT-MOS are revealed through finite-element simulation and microcosmic failure analysis. Under zero turn-<sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">off</small> gate bias, the temperature exceeds the critical limit of melting aluminum and thermal runaway under dc bus voltages of 400 V and 800 V, respectively. The failure mechanism evolves from the fracture of interlayer dielectric to thermal runaway when increasing bus voltage from 400 to 800 V. Under negative turn-<sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">off</small> gate bias, meanwhile, the breakdown of gate trench oxide occurs near the N<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">+</sup> region in the 400 V case and near both the current spreading layer region and the N<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">+</sup> region in the 800 V case. The location of breakdown evolves from a single region to multi-regions from 400 to 800 V. In brief, the article timely provides significant physical insights to better understand short-circuit capability and failure mechanisms and promotes the safe use of SiC <sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">mosfet</small>s in practical power circuits.