Role of Shape Factor in Forming Surface Electric Field Basin in RESURF Lateral Power Devices and its Optimization Design

The drift region shape factor (Ld/t) plays a sophisticated role in affecting reduced surface field (RESURF) effect and breakdown characteristics. In this paper, based on the effective doping concentration (EDC) theory, an Improved EDC concept is proposed to explore the impact of shape factor on 2-D coupling effect in RESURF lateral power devices. The Improved EDC concept indicates that the sophisticated 2-D coupling in N-well resulting an effective N-I-P type drift region. Thus, the surface electric field basin may exist because of the expansion of vertical depletion region. The proposed model presents a more adaptive trait in describing 2-D coupling effect under various device structure parameters when compared to the conventional EDC model. Furthermore, a corresponding structure optimization criterion is provided to further improve the tradeoff between breakdown voltage, On-resistance and costs. The results obtained by the proposed model are found to be accurate comparing with TCAD simulation results.