Research of SEB effects in trench IGBT based on the TCAD simulation

Abstract

In this paper, based on TCAD simulation, a detailed investigation of the SEB failure mechanism of trench IGBTs featuring a deep trench with slanted side-walls structure is conducted for the first time by studying the temporal evolution of electrostatic potential, impact ionization, electric field, current density, and hole concentration distributions. The study reveals that heavy ion irradiation can induce the turning-on of inherent parasitic transistors, leading to the formation of latch-up and consequently SEB. Firstly, the peak electric field transfer leads to high-level impact ionization at the homojunction, injecting ionized electrons into the base-neutral region to turn on the parasitic PNP transistor. Secondly, ionized holes flow through the P-well towards the emitter, diminishing the potential barrier between the P-well and the N+ source region, thus activating the parasitic NPN transistor. Finally, with the parasitic NPN transistor remaining forward-biased, it continuously supplies electron current to the parasitic PNP transistor, thereby sustaining its operation. In summary, the conclusions obtained from the study can provide important references for a deeper understanding of the failure mechanisms of trench IGBT devices in harsh radiation environments.