动态耐压下SOI RESURF器件的二维电场解析模型

摘要

在SOI(绝缘衬底上的硅)器件的设计过程中,为使其具有较高的耐压水平,可优化器件的RESURF(降低表面电场)效应.而在实际电路工作过程中,由于SOI RESURF器件承受动态耐压的缘故,衬底深耗尽效应的存在将会导致衬底耗尽区出现,器件的RESURF效应将会发生改变,从而使器件的实际耐压性能发生改变.基于此,提出动态耐压下SOI RESURF器件的二维电场解析模型,通过求解相应的二维泊松方程,获取新的表面电场分布表达式.并对动态耐压下器件的击穿特性进行分析,阐述动态耐压下促使器件RESURF效应改善的物理机制.与此同时,依据新的表面电场分布表达式,优化衬底掺杂浓度,以使SOI RESURF器件在各类功率集成电路中具有更好的实用性.最后由仿真分析验证了所提模型的正确性.%During the design of the SOI ( silicon-on-insulator) device, in order to make it have a higher voltage level, the RESURF effect of the device should be optimized. However, due to the dynamic voltage of the SOI RESURF device during the actu-al circuit operation, the deep depletion effect of the substrate will cause the substrate depletion region to appear and the RESURF effect of the device will be changed. As a result, the device voltage-withstand performance will be changed. So, a two-dimensional elec-tric field analytical model for SOI ( silicon-on-insulator) RESURF devices under dynamic voltage was proposed. A new surface elec-tric field distribution expression was obtained based on the corresponding two-dimensional Poisson equation solution. According to this model, the breakdown characteristics under dynamic voltage was analyzed and the physical mechanism to improve the RESURF effect of the device under dynamic voltage was described. Simultaneously, to improve the practicality of the SOI RESURF device, the substrate doping concentration was optimized based on the new surface electric field distribution expression. Finally, simulation a-nalysis verified the correctness of the proposed model.