Design And Performance Study For AlN As The Gate Dielectric Material Applied To Nano-scale MOS Devices

With the development of microelectronic technique, the feature size of integrated circuits has scaled down to several decade nanometers. Silicon-dioxide, as the gate dielectric to be used widely in the integrated circuits, will arrive to its physical limits. Thus the selection of high-k gate dielectric materials instead of silicon-dioxide for next generation MOSFET applications has become an interested topic when designing the MOSFET devices.Aluminum Nitride (AlN) belongs to III–V semiconductor compounds with a hexagonal wurtzite crystal structure. Due to its high thermal conductivity, chemical stability, high hardness, high acoustic velocity, large electromechanical coupling coefficient and a wide band gap, AlN thin films have been attracted the extensive interests as a promising candidate electronic material for thermal dissipation, dielectric and passivation layers, surface acoustic wave (SAW) devices and photoelectric devices. In this thesis, we have researched AlN films as the gate dielectric materials of nano-MOS devices theoretically and experimentally.Firstly, fabrication, application and research progress of AlN were introduced. The possibility of AlN as nano-MOS devices was discussed according to the properties such as permittivity, thermodynamic stability, film morphology, interface quality, gate compatibility, process compatibility and reliability, which must be considered in the application.Secondly, the electrical properties of nano-MOS devices using AlN as the gate dielectric material instead of SiO2 were researched. The gate voltage applied can reach 4.3 V, the drain-source saturation current is 5.62×10-9 A, and tunneling current can decrease to about 10-7 A/cm2. Although scaling down the size of dielectric layer, the tunneling current through the gate delectric layer of nano-MOS devices can be improved significantly.Finally, the high-breakdown-field AlN films were prepared by DC reactive magnetron sputtering deposition method and then the influence of sputtering parameters on electrical properties of AlN films was measured and discussed. The results show that the pressure, nitrogen concentration and substrate temperature have a significant influence on the crystallization quality and organizational structure of the films, especially on the electrical properties. The AlN films with well crystallization quality, higher Preferential Orientation and excellent electrical properties can be deposited on the following conditions: 0.5~1.2Pa of working pressure, 70~80% of nitrogen concentration and 400℃of substrate temperature, etc.