The Reliability Study Of Fin Field-effect Transistor At The Atomic Scale

The fin field-effect transistor(FinFET)with great gate control ability,low leakage current and low threshold slope is a crucial technology for semiconductor devices below the 10 nm process.The three-dimensional conductive channel of FinFET devices changes the internal electric field distribution from planar to spatial,which increases the difficulty of fabrication and makes the conventional electrical failure mechanism inapplicable.Thus,the reliability research is of great significance for FinFET devices.This study analyzes devices of the 7-nm-fin and 10-nm-fin FinFET processes with scanning electron microscopy and transmission electron microscopy,and identifies the factors restricting device scaling down.The micro-inspection process was established to ensure the device process reliability.Failure mechanisms of FinFET devices under different electrical stress were analyzed.Combining technology computer-aided design(TCAD)technology,failure analysis was studied and the influencing factors of device reliability were clarified,providing theoretical guidance for the design optimization direction.The specific research results are as follows:(1)Design and process reliability research of the 7-nm-fin FinFET devices.The device design includes layout building,structural parameter setting and flowsheet.Metal interconnection structure is removed in the layout and the reliability of fin structure has a targeted study.In the process reliability research,the 7-nm-fin FinFET devices are validated and compared with the 10-nm FinFET devices.The atomic-scale analysis results show that the fin structure is difficult to etch,and the uniformity of the fin becomes the key factor restricting the scaling down of FinFET devices.The precision of etching technology is of great importance.(2)The electrical reliability research of the 7-nm-fin FinFET devices.Through direct current(DC)technology and transmission line pulsing(TLP)technology,the electrical breakdown under normal operation and electrostatic discharge failure of the FinFET devices are analyzed.The atomic-scale analysis results show that the device structure presents different failure modes.The silicon atom at the fin tip has different growth directions,which results from the harsh heat loss conditions of FinFET devices.Improving the isolation layer insulation and fin tip stability could improve the device electrical reliability.(3)Simulation of device failure mechanism based on the TCAD technology.The electric field distribution in the fin tip is obtained by setting the corresponding electrical test conditions,and the failure mechanisms are clarified.The results show that the difference in electric field intensity distribution in the fin tip affects the epitaxial growth direction of silicon.Combining theory with practice could deepen the understanding of the electrical failure mechanism in FinFET devices.The study on the reliability of FinFET devices in this paper contributes to the device subsequent optimization design.It provides the experimental basis for the reliability study of advanced semiconductor devices below 10 nm.Additionally,the atomic-scale characterization techniques used in this study can realize the visualization of the fin structure.They can also be used to study the reliability of other advanced nanodevices,including low-dimensional semiconductor devices.