MODELING OF THE QUASI-SATURATION BEHAVIOR IN THE HIGH-VOLTAGE MOSFET WITH VERTICAL TRENCH GATE

The quasisaturation behaviour in the high voltage MOSFET structure wit h a vertical trench gate (UMOS) is studied and demonstrated using 2D n umerical simulation techniques. The results show that the quasisaturat ion effect is mainly due to the conduction area and conductance of the drift region becoming the main constraint at high gate voltage and dr ain current levels, A simple analytical expression for the quasisatura tion current using a simple resistive model is derived and verified ba sed on the simulation results. The effect that the geometry of the tre nch has on the quasisaturation behaviour is studied, and it is found t hat increasing the depth and width of the trench improves the quasisat uration operation.