Optimization Design And Research Of Drift Region Of HVT Structure MOSFET

The semiconductor industry has developed rapidly in the past few decades.Under the impetus of Moore’s Law,the size of transistors has been continuously reduced,and the integration and performance of chips have been rapidly improved.Nowadays,the reduction of transistor size encounter huge resistance,the development of the integrated circuit industry enter a"post-Moore era".In order to continue Moore’s Law,the current mainstream research and manufacturing devices are Fin FET and GAAFET.At the same time,the possibility of diversified development of integrated circuits is also being explored.For this reason,three concepts are proposed:“More Moore”,“More than Moore”,"Beyond CMOS",these three directions,have become the focus of research and heated discussions in academia and industry.The HVT structure studied in this thesis was born in the background of this era.The HVT structure adopts a structure similar to a trench gate MOSFET and a vertical channel structure with a fully enclosed gate of VGAAFET,which has good gate control ability and can effectively suppress short channel.It can effectively improve the integration degree while increasing the application flexibility of the device,and the channel length is not limited by the"minimum lithography size",which has inherent advantages in process fabrication.The drift region with the doping concentration lower than the channel region is introduced,which changes the drain withstand voltage region of the device,and at the same time utilizes the carrier accumulation effect of the trench gate,reduces the on-resistance,and makes the HVT structure have low on-resistance,high Pressure-resistant characteristics.This thesis analyzes its mechanism and conducts simulation verification,and completes the following work:1.The effects of the drift region length,doping concentration,trench gate depth and trench gate number on device breakdown voltage and specific on-resistance are explored.The simulation results are summarized and the corresponding optimization scheme is given.The optimized HVT structure’s turn-on voltage V_th is 0.38V,current turn-off ratio can reach 10~7,the breakdown voltage is 3.15V,and the specific on-resistance is 3.22×10~3mΩ·um~2.2.The effects of the drift region length,doping concentration,trench gate depth and trench gate number on the cut-off frequency of the device is explored,the simulation results are summarized,and the optimization scheme of frequency characteristics is given.The optimized HVT structure’s cut-off frequency can reach 245.47GHz.3.The unique manufacturing process of the HVT structure is introduced in detail.Our research group completed the fabrication based on the 0.35um process level,and conducted actual tests on the finished tapes.The test results show that the device has good electrical characteristics.The corresponding comparison simulation is completed and the simulation data compared with the test data.Our feasibility of the HVT structure fabrication process is preliminarily verified.