A Study Of 6H-SiC Heterojunction Source/Drain MOSFET

A novel 6H-SiC metal-oxide-semiconductor field-effect transistor with heterojunctions for source and drain is presented in this thesis. Instead of using heavily doped pn junction, the source and drain regions are completely replaced by polysi-SiC hetreojunctions. This kind of device gives fabrication advantages avoiding the steps of ion implantation and annealing at high temperature usually used for the conventional SiC MOSFET. Also it has not the problems of crystal damage caused by ion implantation and low activation rate of implanted atoms.Firstly, a basic structure of 6H-SiC Heterojunction Source/Drain MOSFET is presented, and the transport characteristics are analyzed.Secondly, the operational mechanism of this device is simulated and its characteristics are comparable to conventional SiC MOSFET from the simulation with 2D device simulation program ISE TCAD. The effects of different oxidatation time,doping concentration of source and drain, oxide thickness, gate length and other factors on the device performance are discussed.Based on the research result, a novel SiC ohmic contact used by n~+ polysilicon/N~+ SiC heterojunction is presented in this thesis. The research results show that the n~+ polysilicon/N~+ SiC heterojunction can form excellent ohmic contact and has the advantages of simple process and excellent performance.Finally, device structure and masks have been designed to fabricate 6H-SiC Heterojunction Source/Drain MOSFET. The advanced structure and the key technologies are discussed. The fabrication processes to be suitable to 6H-SiC Heterojunction Source/Drain MOSFET are developed.The performance, model, simulation and fabrication processes for 6H-SiC Heterojunction Source/Drain MOSFET are investigated in this thesis. This provides the fundamental work for its further research and development.