Impact of 3D simulation on the analysis of unclamped inductive switching

Abstract

Unclamped inductive switching (UIS) is a crucial topic for modern power devices. The UIS failure analysis has been done by 2D Technology CAD (TCAD) simulations due to the restrictions of computation capabilities. In this paper, the detailed UIS failure mechanism for IGBT was analyzed by large scale 3D TCAD simulations. The authors propose that there are two kinds of current filaments. These are avalanche induced current filament and temperature induced current filament. The avalanche induced current filament firstly developed and moved around during the UIS operation. It finally caused local latch-up. The local temperature rapidly increased by the latch-up. This triggered a destructive temperature induced current filament, which stayed in the same location and caused device failure. It was also found that these phenomena were accurately treated only by large scale 3D simulation of at least 160 µm × 160 µm device area.

Effects of Current Filaments on IGBT Avalanche Robustness: A Simulation Study

“…Many studies have shown that when the device operates in the negative differential resistance (NDR) region of the avalanche breakdown curve, a localized aggregation of currents (current filaments) induced by the avalanche effect occurs within the device [4][5][6][7]. The concentration effect of avalanche current leads to the gathering of avalanche energy at the location of the current filament, significantly reducing the device's robustness to avalanche breakdown and possibly leading to device failure [8][9][10][11][12]. When avalanche breakdown occurs in a device due to significant power dissipation, it is generally not feasible to test it directly through experiments.…”