The Optimization Research On The Specific On-resistance Of The Isolating Pillar Superjunction Structure

With the development of the power electronics,power devices are going to occupy more market shares,with further research on the power MOSFETs.In order to overcome the“silicon limit”problem,several innovative structures have been come up with.Among these,superjunction(SJ)MOSFETs,which take advantage of the charge compensation to improve electric field distribution,possess higher breakdown voltage(BV)as well as lower specific ON-resistance(R_on,sp),attracting good graces from the market.Still the structure has drawbacks such as charge imbalance effect owing to the difficulty of fabrication,inferior body diode reverse recovery performance and existing junction field-effect transistor(JFET)effect.Many novel structures,inventions and optimization methods were proposed to relieve those shortcomings.Thus it is of necessity to tap the potential of the SJ structures further more.This thesis establishes the R_on,spand electric field distribution analyzing models of the isolating-pillar SJ and arbitrary trapezoid SJ structures.Through the adequate optimization method,the influence of different design parameters and outside environment is investigated,providing basic data and theoretical support for design.The main innovation of this thesis are:1.Based on the research of the oxide-pillar and compensated pillar SJ structures,unified models of the isolating-pillar SJ structures are proposed.The models are useful for arbitrary dielectric constant of the isolating pillar.It is verified that compensated pillar can not bring improvement compared with the conventional SJ structures,while low-permittivity material is superior with limited ranges of design parameters.2.The electric field and R_on,spmodels of arbitrary trapezoid SJ structures are proposed.The conclusion that there is more superior trade-off between R_on,spand BV in arbitrary trapezoid SJ structures than centrosymmetric SJ structures is drawn with MATLAB and Medici.This thesis investigates the superjunction and its modified structures further,providing analysis and basic theory for the future study.