Modelling of the quasisaturation behaviour in the high-voltage MOSFET with vertical trench gate

The quasisaturation behaviour in the high voltage MOSFET structure with a vertical trench gate (UMOS) is studied and demonstrated using 2D numerical simulation techniques. The the quasisaturation effect is the conduction area and conductance of the drift region becoming the main constraint at high gate voltage and drain current levels. A simple analytical expression for the quasisaturation current using a simple resistive model is derived and verified based on the simulation results. The effect that the geometry of the trench has on the quasisaturation behaviour is studied, and it increasing the depth and width improves the quasisaturation operation