The desaturation and charge recovery behavior for 1200-V RC-IGBTs with diode control is investigated. The low thickness of the drift-region of modern 1200-V IGBTs results in significantly reduced time constants of the diode-control feature. While a low desaturation time constant is well acceptable, the recovery time constant becomes critical when compared to typical locking time requirements of common gate driver units. The impact of different locking times on the overall performance is discussed and a novel device concept for RC-IGBTs is presented which overcomes this issue. The FWD-mode of the novel RC-IGBT is desaturated at a gate-emitter voltage of 0 V allowing for the first time a desaturation pulse pattern which may disregard the locking time requirements of the driving-unit.

A failure mechanism in the edge termination of a 1200V IGBT during overcurrent turn-off is studied with simulations and verified by experiments. The position of the destruction in the experiment can be correlated to the formation of a critical filament in the simulation. The destruction mechanism is investigated in detail. It is only observed if the IGBT enters its current saturation regime. I.e., the IGBT survives a turn-off from the same current level for an increased gate voltage. It is shown that an IGBT provided with a properly-designed High Dynamic Ruggedness (HDR) edge termination structure [1] is no longer susceptible to the destruction mechanism.