Optimization And Implementation Of Epitaxial Layer For IGBT

IGBT(Insulated Gate Bipolar Transistor),a new type multiple-unit semiconductor device combining the advantage of both MOSFET and power transistor,is the representative product of the third technological revolution of power semiconductor devices.IGBT has the following advantages:(1),high input impedance,which could be driven in universal low-cost way;(2),High speed switching characteristic;(3)conducting sate and low loss.It Is a kind of power electronic device applied to medium and high power application,especially to the conversion system with DC voltage of 600 v and above.This paper is studying IGBT silicon EPI growth process under normal pressure,and developing the IGBT silicon EPI self-doped suppression technology.This subject specifies the IGBT silicon EPI growth process optimization technology,with normal pressure equipment.Mainly studies on the following aspects:(1)study on the structure of IGBT power device to find out the critical controllable elements;(2)study on doping mechanism,diffusion effects and self-doped effects to find out the factors influencing the EPI transition area and uniformity of resistivity;(3)to eliminate self-doping effect with dynamic temperature and dynamic deposition rate;(4)study on N/N+/P+ structure theoretical model,to know how the N-EPI self-doped effect could be improved by restraining high concentration P type impurities on N+ layer;(5)propose a method of controlling N+/P+ transition area with Pre-pass doping technology;(6)to control the EPI micro defect via filter of raw material and control of the reaction room environment.Verification results prove that 6” 1200V/20 A IGBT silicon EPI wafers,produced with optimized process,has single wafer resistivity uniformity? 5%,single wafer thickness uniformity? 2%,transition area width? 10 um,dislocation ?500cm-2,surface particle?30ea/pic(??0.3um),meanwhile the other specification could meet GB/T 14139-2009 criteria,completely reach the commercial IGBT silicon material standard.Therefore,the localization of IGBT with silicon EPI could be realized,which establishes the raw material foundation of national independent IGBT production.