负栅极偏置下的SiC MOSFET栅氧老化状态监测

Gate-oxide Degradation Condition Monitoring of SiC MOSFETs With Negative Gate Bias

随着SiC MOSFET的大量应用,其栅氧可靠性成为了备受关注的热点问题。然而现有研究主要关注正应力条件下的老化,对负应力引起的栅氧老化缺乏研究。首先,介绍了SiC MOSFET栅氧老化机理并分析监测参数的影响。然后,建立SiC MOSFET开通过程的高频振荡等效模型,并分析栅氧老化对监测参数,即栅极开通振荡电流峰值的影响。最后通过双脉冲实验和Buck电路研究了负栅极偏置下的开关过程中的SiC MOSFET各特征参数。研究结果表明,负栅偏加速老化200 h后阈值电压降低了51%,栅极开通振荡电流峰值增加了39%,此处的研究可为SiC MOSFET在负栅极偏置下的状态监测提供支撑。

With the widespread application of SiC MOSFETs,the reliability of gate-oxide has become a highly focused hot topic.However,the existing research has mainly concentrated on aging under positive stress conditions,with a lack of investigation into gate-oxide degradation induced by negative stress.Firstly,the mechanism of gate-oxide aging in SiC MOSFETs is introduced,and an analysis of its impact on monitoring parameters is provided.Subsequently,an e-quivalent high-frequency oscillation model for the SiC MOSFET turn-on process is established,and the influence of gate-oxide aging on the monitoring parameter,namely the peak of gate oscillation current is analyzed.Finally,a series of experiments,including double-pulse tests and investigations in a Buck circuit,are conducted to examine various characteristic parameters of SiC MOSFETs during the switching process under negative gate bias conditions.The re-search results indicate that after 200 h accelerated aging under negative gate bias,the threshold voltage is decreased by 51%,and the peak of gate turn-on oscillation current is increased by 39%,this study provides support for the condition monitoring of SiC MOSFETs under negative gate bias conditions.