Study of IGBTs Reliability Under Coupled Electrical–Thermal Environment

Electric field and temperature are two of the most important factors affecting the reliability of IGBT devices. However, the actual effects of coupled electrical-thermal stress on the reliability of these devices have not been studied in detail. In this article, cross-experiments combining different types of reliability experiments, such as high-temperature gate bias, high-temperature storage stressing, and power cycling (PC), are carried out to study the degradation mechanisms in the IGBT devices under coupled electrical-thermal stress. The process of cross-experiments is discussed in detail and a large number of IGBT devices are used for experimental verification. The degradation parameters are monitored and the related mechanisms are discussed for two parts: chip and packaging. Based on the experimental results, a detailed trap formation hypothesis about gate leakage current is proposed. At last, it is qualitatively verified via a finite element model that high-temperature storage helps to release residual stress in bonding wires, and the influence of gate oxide degradation in the PC experiments is explained.