Equivalent Substrate Model for Lateral Super Junction Device

摘要

The equivalent substrate (ES) model and the accordant optimized structure for the lateral super junction (LSJ) device are proposed in this paper. The ES, defined as the combination of the depleted substrate under the reverse voltage and the charge compensation layer (CCL) in the substrate, is treated as a whole to analyze the modulation impact of the compensation electric field $Delta{E}$ on the total electric field of the LSJ. The analytical formulas for the surface electric field profiles of the LSJ are deduced from the 3-D Poisson equation and the Green function. The ES model reveals the essence and the suppression of the substrate-assisted depletion effect in the LSJ, from which the optimized substrate conditions are achieved. The optimized substrate condition allows the LSJ device featuring a similar breakdown voltage to that of the vertical super junction. Then four typical doping concentrations of the CCLs with four different compensation electric field strengths $Delta{E}_{s}$ are compared. The developed novel device with optimized CCL delivers a breakdown voltage of 301 V, realizing 157% improvement compared with the conventional LSJ with ${L}_{d}=15~mu{rm m}$, which shows a superior performance to the LSJ devices reported. It is noteworthy that the ES model can also be used to analyze other LSJs.