Research And Design Of IGBT Based On Ultra-thin Silicon Wafer

Super Junction(SJ)IGBT is a new type of IGBT structure proposed in recent years.The super junction is used to replace the traditional N-type epitaxial layer drift region,which can make the device with a flat electric field distribution even at high doping concentration.And a better compromise between device on-voltage drop and breakdown voltage is obtained.With its performance advantages,super-junction IGBT quickly became a research hotspot in academia.A design and preparation method of1200 V trench gate SJ-IGBT device and its terminal are proposed in this paper.Working principle of the IGBT device and the super junction structure is first analyzed,including the electric field distribution characteristics and carrier transport characteristics of the device under the conduction,blocking and switching states.On this basis,the cells of the super junction IGBT The structure is designed,and the parameters of the drift region super junction structure,the front active region structure and the back ion implantation are simulated and analyzed.A large number of curves and charts are used to show the impact of these parameters on their performance.Finally,the design specifications are met 1200 V,40A SJ-IGBT cell structure parameters.In contrast,the SJ-IGBT in this paper can be implemented on relatively thinner silicon wafer,achieving the turn-on voltage drop of 1.52 V and the turn-off loss of 1.15 mJ.It is worth mentioning that in this paper,in view of the deep trench etching process in the preparation,asymmetric super junction structure cells are proposed.It has wider P-pillar and lower etching depth-to-width ratio,which greatly improves design space and flexibility,reducing the process difficulty.A 1200 V stepped multi-level field plate super-junction terminal structure is proposed.Multi-level metal field plates are used to generate multiple metal ends arranged equidistantly,so that the entire terminal area is depleted longitudinally and has a flatter electric field distribution.It can be seen from the simulation results that under the same terminal width,increasing the number of stages of the metal field plate can greatly improve the withstand voltage value of the terminal.Under the condition of four layers of metal field plate,breakdown voltage of the super junction terminal achieves1250 V.Based on 80?m ultra-thin silicon wafer,the SJ-IGBT process flow simulation isproceeded.The manufacturing process of super-junction IGBT and its terminal is designed based on the Trench+FS process.Relevant designs and simulations have been made on the epitaxy parameters,active area parameters,and backside ion implantation parameters.Finally,the layout design of the chip is completed.