Failure Mechanism Investigations of Type II Short-Circuit in Trench Gate IGBT Device

The type II short-circuit failure mechanism of trench gate insulated gate bipolar transistor (IGBT) is investigated in detail. By using physical TCAD simulations and experiments, it shows that high hole current goes along the trench gate which restructures the electric field distribution under the bottom of the trench gate. As a consequence, a dynamic peak voltage appears under the bottom of trench gate, which results in the gate oxide breakdown during the type II short-circuit process. An optimization structure with reducing the trench gate depth is proposed to suppress the dynamic peak voltage and improve the type II short-circuit robustness for trench gate IGBT.