Investigation on the Robustness During Short-Circuit Turn-off and Its Tradeoff Characteristics With Performance in IGBTs

Abstract

Decreasing the chip thickness of insulated gate bipolar transistor (IGBT) to improve the performance makes the current crowding effect become more pronounced during short-circuit turn-off, especially in the self-clamping mode (SCM). Former researchers have investigated the failure mechanisms during short-circuit turn-off. But the measures to further improve the robustness of IGBT during short-circuit turn-off and performance simultaneously still need more investigations. This paper focuses on the influences of the major device parameters on the robustness of IGBT during short-circuit turn-off, especially in the SCM, and its tradeoff characteristics with performance via symmetrical multicell electrothermal simulations. The results show that wider drift region combined with higher doping concentration, lower saturation current, and larger cell pitch can achieve higher robustness during short-circuit turn-off, but the performance will degrade. Besides, as the current gain increases, there exists the optimum value at which the robustness of IGBT during short-circuit turn-off is the highest. In order to achieve high performance and high robustness during short-circuit turn-off simultaneously, combined with decreasing the chip thickness and current gain, the saturation current should be decreased without compromising the conducting voltage by novel device structure, such as trench shielded planar gate IGBT and high-conductivity IGBT.