Investigations on the Degradations of Double-Trench SiC Power MOSFETs Under Repetitive Avalanche Stress
Investigations on the Degradations of Double-Trench SiC Power MOSFETs Under Repetitive Avalanche Stress
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DOI：
10.1109/ted.2018.2875080
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发表时间：
2019-01-01
影响因子：
3.1
通讯作者：
Sun, Weifeng
中科院分区：
文献类型：
--
作者：
Wei, Jiaxing;Liu, Siyang;Sun, Weifeng
本文研究了双沟槽碳化硅 (SiC) 功率金属氧化物半导体场效应晶体管 (MOSFET) 在重复雪崩应力下的电参数退化。雪崩过程中热空穴注入栅极沟槽底部氧化物被证明是主要的退化机制，而沟道很少受到应力的影响。注入的空穴沿 SiC/SiO2 界面吸引 SiC 层中的额外电子，从而降低导通状态漏源电阻 (R-dson)。由于这个原因，器件的阈值电压（V-th）也略有降低。此外，除了静态电气参数之外，包括器件的栅漏电容(C-gd)和开关特性在内的动态特性也会劣化。在反复受到雪崩应力的作用后，栅极沟槽底部下方的耗尽区变薄，导致C-gd增加，进一步影响开关行为。计算器件的开启和关闭切换时间。结果表明，重复的雪崩应力导致关断过程明显延迟，但几乎不影响双沟槽 SiC MOSFET 的导通行为。
The degradations of electrical parameters for double-trench silicon carbide (SiC) power metal-oxide-semiconductor field-effect transistors (MOSFETs) under repetitive avalanche stress are investigated in this paper. The injection of hot holes into the bottom oxide of the gate trench during avalanche process is demonstrated to be the dominant degradation mechanism, while the channel is rarely influenced by the stress. The injected holes attract extra electrons in the SiC layer along the SiC/SiO2 interface, decreasing the ON-state drain-source resistance (R-dson). Due to this reason, the threshold voltage (V-th) of the device also reduces slightly. Moreover, other than static electrical parameters, dynamic characteristics including the gate-drain capacitance (C-gd) and the switching characteristics of the device also degrade. After being stressed by repetitive avalanche stress, the depletion region beneath the bottom of the gate trench gets thinner, leading to the increase in C-gd, which further influences the switching behaviors. The turn-ON and turn-OFF switching times of the device are calculated. It illustrates that the repetitive avalanche stress results in an obvious delay in the turn-OFF procedure, but hardly influences the turn-ON behaviors of the double-trench SiC MOSFET.