A comprehensive analysis of failure mechanisms: Latch up and second breakdown in IGBT(IXYS) and improvement

The importance of the Insulate Gate Bipolar Transistor reliability has significantly increased due to the widespread use and target application of these devices which includes power conversion and motor drives. The IGBT as an optimal candidate as a power switch for applications requires high current, high voltage and high temperature operation [1], Nevertheless, one of the most important drawbacks of IGBTs is the latch up to the inherent parasitic thyristor structure, which leads to the gate control loss of the collector current and failure caused by second breakdown. The aim of this paper is to study the latch up performance at high operating temperature and to give a short discussion of the second breakdown phenomena during turn off process under disadvantageous conditions of IGBT for IXYS constructor. The circuit used in our study takes into account the effect of elements such as wires, inherent parasitic inductance of resistive elements and packaging. This analysis can help in understanding the operation mechanism with in the device during this condition. This is very helpful in developing optimum device. The need for a good physics based simulator (Spice) to carry out a reliability study is pointed out in this paper. The improvement of the electrical characteristics has been corroborated by focusing the analysis on the dynamic latch up and second breakdown phenomena. Furthermore, our reliability study permits us to improve the implantation of the device in a circuit, as well as its use in industrial operating conditions. Our simulation results indicate a decrease in the latching current density of the IGBT with an increase in the ambient temperature. Transient's characteristics show a decrease in maximum controllable current and an increase in the turnoff time.