Avalanche ruggedness is one of the key factors for safe and reliable power converters deployed in various automotive subsystems. In this paper, the avalanche capability of Power MOSFETs is tested under different repetitive avalanche conditions to differentiate the die degradation and package degradation. While examining the degradation mechanisms, the corresponding electrical parameter shifts are analyzed to better understand the structural changes, root causes, and identify potential precursors for condition monitoring. For this purpose, a high resolution and cost-effective nano-second Current Pulse Generator (CPG) is designed. Thanks to the high resolution PWM function of a digital signal processor (DSP), short current pulses can be generated in the order of 100 picoseconds where the magnitude and duration of the current pulse width can be adjusted precisely. During the experiments, power MOSFETs are stressed under two different pulse widths. It is observed that the on-state resistance gradually increases in both cases yet the roots of the degradations are different. The die degradation and package degradation are responsible for the changes in short pulse and long pulse, respectively. In short pulse case, some devices show saturation in drain leakage current and on-state resistance, while some others show a significant threshold voltage drop, which leads to a noticeable shift of transfer and output characteristics. The electrical parameter shifts indicate a possible gate degradation after the device aging. At the end of the tests, failure analyses are conducted on both devices under test (DUTs) under different stress conditions, revealing different failure mechanisms.

中文翻译：

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汽车功率MOSFET在重复雪崩击穿测试下的性能下降

雪崩坚固性是在各种汽车子系统中部署安全可靠的电源转换器的关键因素之一。在本文中，在不同的重复雪崩条件下测试了功率 MOSFET 的雪崩能力，以区分管芯退化和封装退化。在检查退化机制时，会分析相应的电气参数变化，以更好地了解结构变化、根本原因，并确定状态监测的潜在先兆。为此，设计了一种高分辨率且具有成本效益的纳秒电流脉冲发生器 (CPG)。得益于数字信号处理器 (DSP) 的高分辨率 PWM 功能，可以产生大约 100 皮秒的短电流脉冲，其中电流脉冲宽度的幅度和持续时间可以精确调整。在实验过程中，功率 MOSFET 在两种不同的脉冲宽度下受压。观察到两种情况下导通电阻逐渐增加，但退化的根源不同。芯片退化和封装退化分别是造成短脉冲和长脉冲变化的原因。在短脉冲情况下，一些器件在漏极漏电流和导通电阻方面表现出饱和，而另一些则表现出显着的阈值电压降，这导致传输和输出特性的明显变化。电气参数变化表明器件老化后可能出现栅极退化。在测试结束时，