Research On Key Technology Of SGT-MOS With Integrated Schottky Structure

SGT-MOSFET(Shield-gate Metal Oxide Semiconductor Field Effect Transistor),as a new type of power switching MOSFET,by adding a grounded shield gate SG under the gate of the trench gate MOSFET as an internal field plate,through the depletion of the auxiliary drift region and the isolation of the control gate and the drift region effectively increase the withstand voltage,greatly reduce the gate-to-drain capacitance,and allow higher doping concentration in the drift region to obtain lower on-resistance.In the secondary side management of the power supply of the AC-DC power integrated circuit,the front and rear side of the DC-DC power supply,the intelligent power switch,etc,it is rapidly replacing the traditional single-gate power MOSFET.Nowadays,the market of automotive electronics,industrial automation,advanced communication and Internet of Everything equipment has higher and higher requirements for power switching devices,and SGT-MOS is bound to become the mainstream choice for MOS-type power switches in the future.Foreign manufacturers such as Infineon,Vishay,and ON have launched many SGT-MOS products,and have launched a series of products after many rounds of optimization iterations.At the same time,in order to effectively improve the reverse recovery performance of the body diode,some products integrate SBD(Schottky Barrier Diode)as the body diode.The domestic related field started late,especially in the design and manufacturing experience of P-type SGT-MOS,and there is no related product integrating SBD body diode.This subject carries out research on the main MOS structure and key technologies of SGT-MOS integrated SBD.The main work is as follows:1.Design and simulate and optimize the main structure of the P-type SGT-MOS.Through Sentaurus tool,a P-type SGT-MOS simulation model was built,and the process parameters such as epitaxial resistivity,epitaxial thickness,gate oxide thickness,various implant doses,SG design and other process parameters were simulated and pulled in detail,and the performance of each process parameter was obtained.The specific impact of,and theoretical analysis,further optimize the SGT-MOS simulation model through simulation and analysis results,and finally obtain the optimal parameter configuration,the breakdown voltage is-45.64 V,the on-resistance is 19.7 m?mm~2,input,output,reverse transfer capacitances are 528 p F/mm~2,136 p F/mm~2,and 13.4 p F/mm~2,respectively,and the simulation values are far better than the benchmarks of foreign products.2.The design and simulation technology of SGT-MOS with integrated SBD is studied.According to the anatomy results of the benchmarking foreign products,an integrated SBD scheme with multiple columns of SGT cells and one column of SBD cells in parallel is designed,and the Pi N/Schottky mixed structure MPS(Merged Pi N/Schottky Diode)is used to improve the withstand voltage.The reverse recovery characteristic of the SGT-MOS main structure,MPS structure and SGT-MOS integrated with MPS as the body diode was analyzed,and it was concluded that the addition of the MPS body diode can make the reverse recovery of the SGT-MOS more stable.The maximum reverse recovery current and reverse recovery charge are also significantly reduced at low current freewheeling.The trough terminal supporting the process is designed,and the withstand voltage reaches more than 99%of the cell.According to the process requirements,the layout is drawn and the tape-out is ready.