栅氧老化下SiC MOSFET开通瞬态栅极振荡特性研究

Effect of Gate Oxide Degradation on SiC MOSFET Gate Turn-on Oscillation

栅氧老化问题已成为制约碳化硅(SiC)金属半导体氧化物场效应管(metal oxide semiconductor field effect transistor,MOSFET)可靠性的关键因素,该文尝试利用SiC MOSFET高速开关在变换器中引起的高频开关振荡获取栅氧状态信息,重点研究栅氧老化对开通瞬态栅极高频振荡特性的影响。首先,分析SiC MOSFET栅氧老化机理及其对器件开通时间的影响。然后,建立开通瞬态栅极回路分阶段高频等效电路模型,揭示SiC MOSFET栅极开通振荡电流的形成机理和影响因素。最后,通过33 V高压栅偏加速老化实验进行验证。研究结果表明,随着栅氧老化程度的加深,SiC MOSFET阈值电压会逐渐增加而开通速度变慢,导致栅极开通振荡电流显著减小(约28%)。该文的工作有望为SiC MOSFET栅氧老化在线监测提供一种新的思路。

The gate oxide degradation has become a crucial factor restricting the reliability of SiC metal oxide semiconductor field effect transistor(MOSFET).This paper attempts to obtain gate oxide state information by using the high-frequency(HF)switching oscillations caused by SiC MOSFETs high-speed switching in converters.The effect of gate oxide degradation on SiC MOSFETs gate turn-on oscillation is explored.First,the aging mechanism of SiC MOSFETs gate oxide and its influence on device turn-on time are analyzed.Then,a multi-stages HF equivalent model of gate loop during turn-on transient is established to reveal the formation mechanism and dominating factors of gate turn-on oscillation.Finally,a 33 V high voltage gate bias accelerated aging experiment is conducted for verification.The research results show that the threshold voltage of SiC MOSFETs increases and the turn-on speed becomes slower with the development of gate oxide aging.Consequently,a significant reduction of about 28%is observed in the gate turn-on oscillation current.The presented work is expected to provide a new idea for online monitoring of SiC MOSFETs gate oxide aging.