Optimized Research And Design Of High Voltage And Low Loss Shielded Gate MOSFET

SGT MOS is the shield-gate trench MOSFET,which is a vertical power MOSFET similar to the Cool-MOS.Due to its low process difficulty and production cost,SGT MOS has gradually replaced TMOS which is the original low-voltage discrete device in the past few years to become the main product of low-and medium-voltage power device.Due to the transformation of the semiconductor industry from quantity to quality since the second half of 2022,people have also put forward higher demand for SGT MOS performance.Based on the influence of each structure size of SGT MOS on these two parameters,a design path for optimizing SGT MOS with high breakdown voltage and low loss can be designed,so that the performance of SGT MOS can be iteratively updated on the basis of existing products.In addition,the new SGT MOS structure is also a hotspot of SGT MOS research,one of which is the short channel SGT MOS research.Short channel SGT MOS can reduce its channel resistance to improves its performance.At the same time,the short channel SGT MOS can reduce the threshold voltage due to various short channel effects,so it can get a lower threshold voltage at higher channel doping and widen the range of devices.This thesis summarizes and validates a design path for 60V SGT MOS by studying the size parameters of SGT MOS.Based on this path,the characteristics,problems,solutions and design scheme of short channel SGT MOS are studied.In this thesis,five parameters of SGT MOS:trench depth,drift zone length,drift zone width,drift zone doping concentration,and field oxide layer thickness are simulated and analyzed.The effects of these five parameters on the breakdown voltage and specific on-resistance of SGT MOS were analyzed.According to the degree of influence of these five parameters on the performance of SGT MOS,the difficulty of process change,and the difficulty of design,they are divided into major parameters,secondary parameters and structural parameters.The SGT MOS optimization design method by sequential design of different parameters is given,and a 60V SGT MOS scheme is designed by this method.The simulation results show that the breakdown voltage is 66.52V,the specific on-resistance is 13.07 mΩ·mm~2,and the threshold voltage is 1.848V.On this basis,the research of short-channel SGT MOS is carried out,and the problem of the low breakdown voltage of the device in some cases caused by the premature depletion of P-body is solved by adding a low-doped N-type isolation layer,and two processes for forming N-type isolation layer are proposed.Finally,a 60V short-channel SGT MOS optimization scheme is designed according to the previous SGT MOS optimization design method,and the breakdown voltage is 66.2V,the specific on-resistance is 13.44 mΩ·mm~2,and the threshold voltage is 1.468V.