Investigation of a power FLIMOSFET based on two-dimensional numerical simulations

Abstract

This paper presents the numerical simulation results for a power FLIMOSFET structure with up to eleven vertical floating islands, designed using PISCES-IIB, a 2-dimensional advanced device simulator. The novel structure is based on the FLI-diode concept, which helps in lowering the maximum electrical field in the N^–epitaxial region of the device to reduce the effective on–resistance without degrading device performance. Extensive simulations were performed to understand the device physics through various internal electrical quantities like potential distribution and electric field in different regions of the device both in on/off states. The effect of drift region doping on the device performance has been discussed. It is shown that the decrease in the drift region doping tends to decrease the electric field distribution and intermediate potential in this region thereby making its on-resistance lower than the value given by the conventional silicon limit. The device structure does not require any precise control of the boron implantation dose in the P⁺ floating islands for charge balance as essential in case of super junction (SJ)/COOLMOS^TM devices. The process flow mechanism required to fabricate FLIMOSFET structure using multi-epitaxial technology has been discussed, which is less complex and less expansive than the super junction (SJ) devices technology.