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Key criteria for the short-circuit capability of IGBTs

Authors & Affiliations

V. van Treek, H.-J. Schulze, R. Baburske, F. Hille, F.-J. Niedernostheide, and F. Pfirsch,

Infineon Technologies AG, Neubiberg, Germany

DOI

10.14311/ISPS.2021.001

Abstract

Short-circuit behavior and capability are investigated and optimized during IGBT development. Thereby,
knowledge about destruction and high-frequency short-circuit oscillation mechanisms is needed. For the
thermal destruction mechanism, filaments are formed shortly before destruction during the thermal runaway itself, whereas for the electrical destruction mechanism strong current filaments are formed by an
electrical mechanism, before the self-heating in the filaments leads to a thermal runaway. At low
collector-emitter voltages, weak non-destructive filaments exist for a large current range. For both the
filament formation and short-circuit oscillations (SCOs), an electric-field peak in the field-stop layer and
a quasi-plasma layer beneath the MOS cells are mandatory. For SCOs, which are caused by a periodic
storage and release of charge carriers inside the device, additionally, a weak electrical field at the beginning of the drift zone is necessary. Weak, non-destructive filaments and SCOs are likely to occur
simultaneously. An increase of the bipolar current gain reduces the operating area with SCOs and
increases the electrical short-circuit capability. A simultaneous reduction of the thermal short-circuit
robustness can be avoided by advanced p-emitter concepts or (over-)compensated by an improved
thermal setup.

Keywords:

IGBT, short circuit, thermal short-circuit robustness, electrical short-circuit robustness,
short-circuit destruction, high-frequency short-circuit oscillations, SOA

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