A New Physical Understanding of Lateral Step Doping Technique via Effective Concentration Profile Concept

The drift region doping profile plays a significant role in affecting the performance of lateral power devices on silicon-on-insulator (SOI) substrate. However, due to the modeling difficulty of the 2-D solution, the physical meaning of which still remains unclear. Thus, a novel effective doping profile concept is proposed to explore the physical insight of the surface electric field (EF) reshaping as a result of the step lateral doping profile. Through the effective concentration profile (ECP) theory, the sophisticated 2-D relationship between lateral step doping profile (SDP) and reduced surface field (RESURF) effect can be simplified to the fluctuation of the 1-D effective doping profile. A 1-D ECP model is presented accordingly to qualitatively and quantitatively explore the influence of SDP on the surface EF and breakdown voltage (BV) improvements. Furthermore, the designing criterion of drift region SDP is proposed with the help of the analytical model, which provides a useful guidance for realizing the optimized surface EF and BV in devices with SDP.