6H-SiC lateral power MOSFETs with an asymmetrical buried oxide double step structure

Abstract

A novel 6H-SiC lateral power MOSFET structure has been proposed with asymmetrical buried oxide double step which improves breakdown voltage. Extra step introduced in the buried oxide enhances peak electric Held and is positioned in the middle of the drift region to maximum breakdown voltage. Using thin-film layer on top of the buried oxide, facilitates employment of high impurity concentration and results in reduction of on- resistance. The doping concentration of drift region , height of step in buried oxide and difference in the thicknesses of buried oxides have been optimized by using device simulation ,to reduce the surface electric field crowding. While lateral power MOSFETs with asymmetrical buried oxide double step structure fabricated on SOI substrate exhibit a maximum breakdown voltage of 245 V with doping concentration of 3.5 times 1016cm-3 in drift region , a 6H-SiC lateral MOSFETs show a characteristic breakdown voltage of 2015 V with doping concentration 1.2 times 1017c-3 in the drift region.