Under unclamped inductive switching (UIS) condition, there is non-uniformity in the intra-chip distribution of avalanche breakdown current in insulated gate bipolar transistors (IGBTs). The “current filaments”, which are concentrations of current caused by the parasitic PNP transistor, move through the chip and are thought to be related to failures. During the avalanche breakdown, the charge bremsstrahlung generates light over a wide wavelength range. We have previously reported that we constructed an observation system using a photomultiplier tube (PMT) and observed the avalanche breakdown photoemission with nanosecond time resolution. In this study, we used the same observation system to observe the photoemission behaviour of the samples in which the metal electrode was partially removed with a FIB (focused ion beam) to create a defective contact area. In the sample with the pseudo-defect, (a) there was an abnormal emission peak that did not correspond to the avalanche current change, (b) the randomness of the behaviour for each single pulse became extremely low, and (c) the pseudo-defect itself did not trap the current filament. These results may explain the tendency of IGBTs to have a higher probability of failure during repetitive avalanche breakdowns if they contain some defects.

在非钳位感应开关 (UIS) 条件下，绝缘栅双极晶体管 (IGBT) 中雪崩击穿电流的芯片内分布不均匀。“电流丝”是由寄生 PNP 晶体管引起的电流集中，穿过芯片并被认为与故障有关。在雪崩击穿期间，电荷轫致辐射会在很宽的波长范围内产生光。我们之前曾报道，我们使用光电倍增管 (PMT) 构建了一个观察系统，并以纳秒时间分辨率观察了雪崩击穿光电发射。在这项研究中，我们使用相同的观察系统来观察样品的光电发射行为，其中金属电极被 FIB（聚焦离子束）部分去除以产生有缺陷的接触区域。在具有伪缺陷的样品中，（a）存在与雪崩电流变化不对应的异常发射峰，（b）每个单脉冲行为的随机性变得极低，以及（c）伪缺陷- 缺陷本身没有捕获电流灯丝。这些结果可以解释 IGBT 在重复雪崩击穿期间具有更高故障概率的趋势，如果它们包含某些缺陷。(b) 每个单脉冲行为的随机性变得极低，并且 (c) 伪缺陷本身没有捕获电流灯丝。这些结果可以解释 IGBT 在重复雪崩击穿期间具有更高故障概率的趋势，如果它们包含某些缺陷。(b) 每个单脉冲行为的随机性变得极低，并且 (c) 伪缺陷本身没有捕获电流灯丝。这些结果可以解释 IGBT 在重复雪崩击穿期间具有更高故障概率的趋势，如果它们包含某些缺陷。