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

Abstract

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 shortcircuit 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 I c -V ce SOA-diagram. The impact of the stray inductance L stray and the gate resistor R G 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.

Investigation and Classification of Short-Circuit Failure Modes Based on Three-Dimensional Safe Operating Area for High-Power IGBT Modules

“…As explained in Part B, the IGBT ruggedness to resist the upper short-circuit pulse failure increases with the rising VDC. Thus, at high VDC/Vrated region of the device full-voltage range, this failure mode is less crucial for restricting ISC_allow, and then there comes the influence of turn-off failures [20,32,36]. For an IGBT operating under short-circuit conditions, three different kinds of turn-off failures probably occur to destroy the device.…”

“…This is to say, the relative values of the triggering voltages for the self-turn-off failure and turn-off failure during the steady state against Vrated are more approaching to 1. In other words, as limiting factors for the IGBT short-circuit VDC/Vrated-ISC SOA, these two turn-off failures will play dominating roles in high-ratio region of the device full-voltage range [20,32,39].…”

TCAD simulation of current filamentation in adjacent IGBT cells under turn-on and turn-off short circuit condition

“…8. The lateral current flows are driven by the potential difference between the filament cells and the adjacent non-filament cells [3]. Fig.…”

“…current filamentation) occurs, because such an effect induces strong local self-heating and restrict the turn-off capability of the switch. In previous works [1][2][3], strong collector side electric field strength (E collector ) is claimed to be one of the relevant factors for the onset of current filaments. However, cause-effect relationship between E collector and filamentation has never been completely clarified.…”

Al modification as indicator of current filaments in IGBTs under repetitive SC operation

“…Many authors have investigated the SC-SOA for different voltage classes ranging from 1200 to 6500 V [1][2][3][4][5][6][7][8][9]. A hypothesis was developed for device destruction based on simulation results, explaining the avalanche generation rate exceeding the critical value near n-base/n-field-stop junction [6][7][8].…”