Theory of an improved vertical power MOSFET using high-k insulator

An improved structure of the vertical power MOSFET using high-k insulator (Hk-MOSFET), which has a better relationship between specific on-resistance (Ron) and breakdown voltage (VB) than the conventional Hk-MOSFET and the superjunction MOSFET, is studied. An analytic model of this improved Hk-MOSFET is proposed, which can be used to well explain the physical reason of the improvement as well as to obtain an optimal design. It is found that the theoretical results match well with the numerical simulation results, where the errors of VB and Ron are both less than 7%. Moreover, the numerical simulation results show that, with the guidance of the proposed analytic model, Ron of the improved Hk-MOSFET can be optimized to be about 30%-50% lower than that of the conventional Hk-MOSFET with VB = 300-1000 V.