Simulation model and parameter extraction of Field-Stop (FS) IGBT

In view of the differences between FS layer and Buffer layer in width and doping concentration as well as the differences between the doping concentration and the excess carrier lifetime in the N-base, an improved FS switching transient model for FS IGBT has been established by applying a high-level injection assumption to the FS layer and taking the recombination of the excess carrier into account. Some improved simplified methods for parameter extraction and data processing have also been proposed based on the measurement of the port electrical characteristics of IGBTs. The experiment results show that there are different temperature characteristics when IGBT is in the turn-on or turn-off transient. The analysis of the experimental phenomenon has come to a conclusion that the base excess carrier lifetime has a great influence on the temperature characteristics of switching transient. Therefore, an improved electro-thermal model of IGBT has been presented to simulate the turn-off tail current and the whole switching transient of IGBT at different temperatures. By the comparison between the simulated and the measured results, the proposed model is proved to be more accurate, and the conclusion is correct.