Effective Concentration Profile Theory:a New Physical Insight Of Breakdown Mechanism And Electric Field And Potential Model For Lateral Power Device

The development of lateral power devices has made revolutionary progress as the introduction of reduced surface field(RESURF)technique.The Lateral Double diffusion MOS(LDMOS)using RESURF principle has become the basic component of High Voltage Integrated Circuit(HVIC)and Smart Integrated Circuit(SPIC)for its high breakdown voltage(BV),low on-resistance(Ron),low power loss and high integration.Driven by the unresting demands for high performance and low costs,the utilization,and expansion of RESURF theory have been constantly considered as a key topic in the realm of power electronics.One of the key challenges for the designing lateral power devices is to obtain high BV and low specific Ron.Yet,the physical insight of the inherited 2-D coupling effect in RESURF structure is still not clear.Furthermore,as more and more new device structures have been reported,the corresponding analytical model is more and more complicated.More importantly,as the device dimensions continue to decrease,the effect of 3-D curvature will become more and more severe.Therefore,the current 2-D breakdown theory and model can no longer optimize the real world devices.This dissertation focuses on the breakdown characteristic of the most widely used Bulk Silicon(BS)and Silicon on Insulator(SOI)lateral power devices.Using 1-D approach,the Effective Concentration Profile theory(ECP)has been proposed to conduct an innovative study on breakdown theory.The ECP theory considers that the 2-D and 3-D breakdown voltage techniques achieve surface field reshaping via equivalently changing the doping profile of drift region.In light of that,the ECP models are proposed to provide physical insight on Single RESURF,Double/Triple RESURF and Field plates assistant RESURF lateral power device.In addition,the ECP theory is applied to study the impact of 3-D layout curvature effect on device breakdown characteristics,and a corresponding analytical model is proposed as well.Two 1-D breakdown theories include:1.Single RESURF breakdown theory and its 1-D model.The BS/SOI Single RESURF ECP theory is proposed to illustrate the surface field reshaping of RESURF technique on both bulk silicon and SOI substrate.Using the Effective Concentration Profile profile,the distinctive surface electric field of RESURF structure has been explained for the first time.By merely solving 1-D Poisson equation,the ECP theory can provide simple but accurate 2-D field and potential distribution.Furthermore,the breakdown voltage model is also obtained which has simple and clear mathematics expressions.Based on which,a structure optimization window of the drift region is obtained to provide theoretical guidance on device designing.2.Double/Triple RESURF breakdown theory and its 1-D model.To unify the breakdown theory of various device structure,the ECP theory is expanded and applied on Double and Triple RESURF structures.By equivalent the changes of drift region doping profile to the variation of ECP profile,the ECP breakdown theory is systemized.By equivalenting the double and triple RESURF structure to a single RESURF drift region,a pervasive ECP theory is proposed which can accurately demonstrate the surface electric field profile and breakdown characteristic.Based on the in-depth discussion on the D/T-RESURF effect,its physical insight is provided with the corresponding optimization criterion.Two active region Junction Termination Effects on breakdown characteristics:1.Field plates assistant RESURF breakdown theory and its 1-D model.A novel Field Plate RESURF breakdown theory is proposed using ECP principle.In which theory,the surface charge modulation effect induced by field plates are considered as the outcome of the joint action between ECP and effective characteristic thickness.Accordingly,the ECP FP-RESURF 2-D field potential and BV models are established to provide physical insight of field plate effect.Using the proposed 1-D model and ECP theory,the field plate geometric optimization criterion is proposed which provide theoretical guidance to the device optimization.Our study indicates that one of the biggest challenges in field plate designing is the trade-off between drift region dose and process tolerance.2.Study on 3-D layout curvature effect induced surface field crowding effect.Using the ECP theory,this work focus on the inevitable 3-D layout curvature effect and its increasing impact on device breakdown voltage.The corresponding 3-D breakdown model is obtained via simple 1-D ECP theory for the first.So that,the complicated mathematics expressions are prevented while maintaining high accuracy on describing the device reverse characteristics.Using those models,the 3-D layout induced surface electric reshaping effect is studied,the sensitivity of breakdown voltage and surface electric field crowding on device structure is demonstrated in detail for the first time.Our study indicates that when the radius of inner ring region is three times larger than characteristics,the adverse effect of 3-D layout can be suppressed greatly.