Breakdown theory of a new SOI composite structure

The new SOI composite structure and its breakdown model are proposed in the paper. The U-type reducing field (URF) structure in lateral direction and the located-hole interface charge (LIC) model for high voltage in vertical direction are developed. By locating hole charge at the interface between the insulator and silicon layer, and satisfying displacement flux continuity, the electric field in the insulator layer is raised from 3 times that of the silicon critical electric field E_C,Si to the critical electric field of the insulator SiO₂ E_C,SiO(2), breaking through the vertical breakdown limit of conventional SOI devices. In the lateral direction, the analytical electric field and potential profiles of the URF are given by decomposing the 2D Poisson equation into two 1D equations. The tradeoff between breakdown voltage and on-resistance are explored according to the simulation and analytical results.