THERMO‐ELECTRIC STUDY OF THE TRENCH‐GATE POWER VDMOS TRANSISTOR

In this paper, the 2‐D numerical analysis is used to investigate the electro‐thermal performance of a trench power VDMOS transistor having a much reduced quasi‐saturation effect over the conventional VDMOS structure. Taking into account all the appropriate physical mechanisms, the analysis self‐consistently solves Poisson's equation, the electron continuity equation and the heat flow equation. The results show that the trench structure introduced enables the device to operate at higher current levels due to a favorable change in current density distribution within the device. However, these two effects can increase the self‐heating of the device, decrease the forward current and degrade the thermal stability of the new structure. Nevertheless the new device is still found to provide a higher quasi‐saturation current than the conventional VDMOS device even when thermal effects are taken into account.