Effective Doping Concentration Theory: A New Physical Insight for the Double-RESURF Lateral Power Devices on SOI Substrate

Double-reduced surface field (D-RESURF) technique aims to increase the doping concentration of drift regions and maintain a high breakdown voltage. However, conventional 2-D models are too complicated and unable to elaborate its physical meaning. Hence, the D-RESURF effective doping concentration (EDC) theory is proposed in this paper to explore the physical insight of the D-RESURF effect by equating the sophisticated 2-D structure to a simple 1-D RESURF model with segmented-doped p-n junction. The EDC indicates that an NPNP structure may exist because of the influence of the P-top region. Thus, two electric field valleys and one electric field peak can be formed on the surface. Based on the theory, a 1-D analytical model is presented to qualitatively and quantitatively explore the impact of D-RESURF effect on breakdown mechanism of silicon on insulator lateral double diffusion MOS. The results obtained by the proposed model are found to be sufficiently accurate comparing with TCAD simulation results.