Christian Jaeger

Comparison of critical current filaments in IGBT short circuit and during diode turn-off

Device simulations of two-dimensional structures with a huge lateral extension indicate that the combination of lateral current flow and a vertical reduction of space-charge region are necessary for the filament formation during the short-circuit operation of IGBTs and the turn-off of diodes. The shape of the electric-field distribution is introduced as new criterion to estimate the rising branch of the short-circuit destruction curve in the Ic-Vce SOA-diagram. The impact of the stray inductance Lstray and the gate resistor RG on the short-circuit destruction limit are experimentally investigated. The presented results allow a deeper understanding of the different electrical short-circuit failure mechanisms (turn-on, quasi-stationary state, turn-off) and their relation to one another.

The effect of different stray inductances on the performance of various types of IGBTs — Is less always better?

In this paper, the effect of different stray inductances on the performance of various combinations of different types of IGBTs and freewheeling diodes was studied. Therefore, a fast switching IGBT4 High-Speed was combined with either a SiC Schottky diode or a Si bipolar diode. It was analyzed how the switching losses are affected by the type of the freewheeling diode, the stray inductance and to what extent a faster switch and diode can be exploited in a low inductance circuit.

A new sub-micron trench cell concept in ultrathin wafer technology for next generation 1200 V IGBTs

The overall growing trend towards electrification and, at the same time, the urgent need to minimize energy consumption strongly requires higher energy efficiency in power electronics. We present a new technology concept for next generation 1200 V IGBTs with vastly reduced overall power losses using an optimized micro-pattern trench (MPT) cell design with sub-micron mesas. Further important parameters relevant for inverters driving electrical machines were optimized, including turn-off softness, dv/dt-controllability, and short circuit capability, providing a right-fit solution to customer requirements.

Critical overcurrent turn-off close to IGBT current saturation

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.