Design And Implementation Of Shielded-gate MOSFETs

Shielded-Gate Trench MOSFET(SGT)is the most advanced MOSFET technology in the commercial low and medium voltage field,SGT uses the two-dimensional charge balance principle to break through the traditional power MOSFET's“limit of silicon”(R_ON(SP)?BV^2.5).Compared to conventional trench MOSFETs,its shield gate acts as a field plate in the drift region within the body,giving SGT a significant advantage in terms of specific on-resistance R_ON(SP)and figure of merit(FOM=Ron*Qg),which can effectively improve the energy utilization efficiency of the system.As an energy-consuming super country,the popularity of SGT has great economic value and environmental benefits.In low-voltage,high-current applications,such as switching power supplies,SGT replaces conventional diodes for synchronous rectification to significantly reduce conduction losses.In this application scenario,the intrinsic diode in SGT conducts during the off time,and its reverse recovery characteristics become a limiting factor for switching frequency and efficiency,so improving SGT reverse recovery characteristics has significant application and market implications.In this paper,we will realize the design and flow of 150 V SGT and optimize its fast recovery characteristics based on this platinum doping process.The followings is the main work of this thesis.1.Simulation of device structure based on theoretical analysis and derivation of equations using TCAD simulation tool-Sentaurus.The main datas are epitaxial layer thickness,epitaxial layer concentration,mesa width,and shield gate oxide thickness.After that,the terminal and layout are designed to stabilize the breakdown voltage above155 V,and finally the optimal value range of each structure parameter is obtained.2.Combined with the mature SGT manufacturing process of the cooperative process line,the 150V SGT obtained from the simulation is flowed and verified by the process.Finally,the finished SGT with the desired dynamic and static characteristics is obtained.3.The platinum doping process is selected as the means to achieve the fast recovery characteristics of this product by using the minority carriers life time control technology,and finally the SGT with excellent fast recovery characteristics is obtained.4.Finally,the application results of the final sample in actual work are described,and its application performance is not much different from that of the benchmark product,which meets the design expectations.In this thesis,a 150 V SGT with fast recovery characteristics is implemented,which has a breakdown voltage of 160.2 V,on-state resistance of 8.15 mohm,and reverse recovery characteristics of Trr=42.3 ns and Qrr=31.5 nC.