Performance and reliability comparison of power DMOSFET structures with and without an integral Schottky diode

This paper reports on the results obtained from a study of the performance and reliability characteristics of two low-voltage power MOSFET structures. Both structures were fabricated using ultrahigh cell density self-aligned refractory TiSi₂ gate and contact technology. In the power MOSFET structure with an integral Schottky diode (ISMOSFET), approximately 5% of the total number of cells were used for incorporating a Schottky diode in parallel with the parasitic PN-junction diode inherent in the MOSFET structure. Two-dimensional (2D) mixed device and circuit simulations were used to study the unclamped inductive switching (UIS) characteristics. It is shown that the ISMOSFET structure performs similarly to the MOSFET structure under UIS conditions. The former, however, results in more than 30% improvement in the reverse recovery performance with no degradation in the on-state power loss and off-state blocking voltage rating. The simulation results are shown to be in excellent agreement with the measured data