A New Split Gate Resurf Stepped Oxide UMOSFET Structure with High Doped Epitaxial Layer for Improving Figure of Merit (FOM)

Abstract

The split gate resurf stepped oxide with highly doped epitaxial layer (HDSGRSO) UMOSFET has been proposed. The epitaxial layer of HDSGRSO u-shape metal oxide semiconductor field effect transistor (UMOSFET) has been divided into three parts: the upper epitaxial layer, the lower epitaxial layer and the middle epitaxial layer with higher doping concentration. The research shows that the reduced SURface field (RESURF) active has been enhanced due to the high doped epitaxial layer, which can modulate the electric field distribution and reduce the internal high electric field. Therefore, the HDGRSO UMOSFET has a higher breakdown voltage (BV), a lower on-state specific resistance (RSP) and a better figure of merit (FOM). According to the results of Technology Computer Aided Design (TCAD) simulations, the FOM (BV2/RSP) of HDSGRSO UMOSFET has been improved by 464%, and FOM (RSP × Qgd) of HDSGRSO UMOSFET has been reduced by 27.9% compared to the conventional structure, respectively, when the BV is 240 V. Furthermore, there is no extra special process required in this advanced fabrication procedure, which is relatively cost-effective and achievable.