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.