UIS Analysis and Characterization of the Inverted L-Shaped Source Trench Power MOSFET

In this paper, the unclamped inductive switching (UIS) behavior of an inverted L-shaped source trench power MOSFET is numerically analyzed and experimentally characterized. The measured avalanche energy absorption at UIS of the new trench power MOSFET is 2.1 times that of the conventional trench power MOSFET. This is explained by numerical simulation, which shows that the voltage drop across the emitter/base junction in the parasitic bipolar junction transistor of the new structure is smaller than that of the conventional structure. The influence of structural and device size variation of the new trench power MOSFET on UIS performance is also investigated. Results show that the avalanche current density at UIS is a strong function of the p
⁺
-region width and the device size. Furthermore, the effect becomes very significant as the device size becomes very small.