Analysis of clamped inductive turn-off failure of multi-finger lateral IGBT in SOI single chip inverter ICs

The clamped inductive turn-off failure of Silicon-on-Insulator Lateral Insulated Gate Bipolar Transistor (SOI-LIGBT) with multi-finger layout pattern is investigated in this paper. Firstly, the measurements of device failure under clamped inductive turn-off are discussed. Secondly, simulations are carried out to reproduce the failure by using Sentaurus TCAD. It is found that the failure origins from the inhomogeneous depletion behavior among the fingers, leading to the non-uniform current-sharing and the subsequent current crowding in single finger. As a result, the NPN transistor is activated, and eventually resulting in destruction of the device. Lastly, an improved structure with deep-oxide trenches arranged between the adjacent fingers is fabricated and no failure occurs when the device turns off under high-voltage and high-current conditions.