有场限环和横向变掺杂的平面结二极管电场分布的二维数值分析

The 2-D Numerical Analysis of Electrical Field Profiles of Planar Diodes with Floating Field Limiting Rings and Variation of Lateral Doping

本文提出了在模拟有浮空场限环(FFLR's)和横向变掺杂(VLD)结构的表面电场分布中所采用的一种新技术和新的环区边界条件,即低场点(LFP)边界条件。利用该技术在求解Poisson方程时,便能方便迅速正确地对具有上述结终端结构的平面结二极管的反向击穿特性进行二维数值模拟;同时,为进一步克服由于高反偏压导致的低求算效率,本文引入一套与外加偏压相关的归一化参数对Poisson方程进行归一化,并给出归一化参数随外加偏压变化的经验公式。利用上述技术,分别对平面结二极管以及具有双FFLR's的结构和由五段Gauss掺杂分布形成的VLD的结构的平面结二极管的表面电场进行二维数值分析,得到了满意的结果。

In this paper, the new technique and the new boundary condition (Low Field Point--LFP) are introduced in the 2-D numerical simulation of the electrical field profiles of planar diodes with Floating Field Limiting Rings (FFLR's) and Variation of Lateral Doping (VLD). By making use of this technique, the breakdown characteristics of the diode with FFLR's and VLD's can be simulated correctly and speedily, if only Poisson's equation is solved. To overcome the shortcome of low calculation efficiency at high voltage conditions, a new set of scaling factors, which are related to the maximun of the applied voltages, are introduced to scaling Poisson's eqn. The empirical formula of the ratio of the scaling factor to the applied voltage is given. Finally, the planar diode with two FFLR's and a VLD which is formed by the composed doping of five Gaussian type distributions are simulated respectively, and the correct distributions of the electrical field and the potential are obtained.