Simulationsuntersuchungen zur Grenzbelastbarkeit von IGBTs im Abschaltvorgang

Abstract

Within the frame of this thesis turn-off behaviour of IGBTs was investigated, focussed on Trench IGBT design. Temperature was introduced as additional mean for the device's behaviour. The existence of filament oscillations is proved. Neighbouring relations influence the sequence of the current-concentration carrying transistors. The filament self-extinguishing through plasma extraction is shown as driving force for the filaments' transition from one IGBT to another. Gate backlash was recognized as a reason for oscillation. The parasitic capacity of trench IGBTs was devoted attention. The oscillation itself as destructive mechanism was ruled out. It became clear, that temperature and thermal runaway make up the final destruction mechanism. Thermal feedback is the prerequisite for a stable local latch-up. Considerations were taken to provide conditions for informative, yet fast to be computed simulation setups. Variants of the trench cell were examined regarding their turn-off capabilities.