A novel partial SOI EDMOS (>800 V) with a buried N-type layer on the double step buried oxide

•Partial silicon-on-insulator extended drain MOSFET is proposed.•Two new electric field peaks are introduced by the double step BOX layer.•The electric field in the BOX layer is enhanced by the buried N-type layer.•The proposed structure improves the breakdown voltage.•Self-heating effect is suppressed in the proposed structure.

In this paper, a high voltage partial silicon-on-insulator (PSOI) extended drain metal–oxide–semiconductor (EDMOS) field effect transistor with a buried N-type layer (BNL) on the double-step buried oxide (DSBOX) is proposed. Due to the DSBOX, two additional peaks of the electric field are introduced in the drift region, modulating the electric field, achieving a more uniform distribution in the drift, and improving the lateral breakdown voltage (BV). The BNL provides a great population of positive charges on top of the DSBOX and enhances the electric field in the BOX, leading to a higher vertical BV. Moreover, the silicon window provides a thermal conduction path from the active region to the substrate, significantly alleviating the self-heating effect (SHE) in comparison to the conventional SOI-EDMOS (C-SOI).