The Research And Design Of Superjunction Mosfet And High-k Mosfet

As the key component in modern power electronic system,power Semiconductor devices still play a important role in our modern life from the day when it was invented in1970 s.Its application fields varies from consumer electronics,automotive electronics system,to Industrial equipment and smart grid.evenly includes the aerospace and marine system.but to all members of power electronics employees,the most important concern and consideration of power MOSFET is how to improve the performance of semiconductor device and exert the best outstanding characteristics of power semiconductor devices in the field of energy controling.In the last 40 years,some newly developed device structure has been proposed,which shows better performance than the before ones.In this thesis,wo will select superjunction and HK MOSFET as the objects of disscussion,and shows how this two devices break the traditional “silicon limit”.In the introduction part of this thesis,we will introduce the cells and termination's historical evolution and its present and future development of power semiconductor devices,and mainly focus on cells structure such as VDMOSFET,UMOSFET and IGBT and termination structures such as JTE,VLD.In the second part of this thesis,we will derive the superjunction and HK MOSFET by the theory of how to break the traditional “silicon limit”,and then introduce several superjunction manufacturing technology such as:multistep epitaxy growth,deep groove etching and epitaxy filled,and multistep high energy ion implantation.In the third part of this thesis,we will show the design theory of strip cell structure of Superjunction and then design a cell stureture breaking down at 500 V,then verificate that when the ionization rate integral reaches 1 at several critical electric field lines,the super junction obtains the minimum on resistance.then shows that with the improvement of depth with ratio of superjunction,its resisitance decreases.at last discuss the electric distribution model of superjunction with charge imblance.In the fourth charpter,we discuss the design theory of HK MOSFET,Firstly introduce the design Prinpicle of strip structure of HK MOSFET,and then using this prinpicle to design a HK MOSFET at a given breakdown voltage.and then study the resistances and output charcteristics of HK MOSFET,superjunction and trational VDMOS,at last we study the improved structure of HK MOSFET.