High-speed 600V NPT-IGBT with unclamped inductive switching (UIS) capability

In this paper, a new design concept is proposed for 600V IGBTs to achieve both fast switching and unclamped inductive switching (UIS) capability. The concept is based on optimizing p-emitter efficiency (γ) for each condition of on-state and sustaining mode. Here the γ is reduced in on-state to lower the turn-off loss, but kept enough in sustaining mode to suppress the electric field. In particular, it is show that the γ of more than 0.4 in sustaining mode prevents the short-time UIS failure. The concept was successfully applied to NPT-IGBT, and the fabricated device has demonstrated fast switching adaptable to a frequency of 150 kHz and UIS capability of 28mJ/mm² at a high current density ( J_C) of 200A/cm₂ (about 6 times the J_C of MOSFETs).