Preparation Of A Ruthenium Oxide Dielectric Layer By Solution Method And Its Application In Thin Film Transistors

With the development of integrated circuit, the level of integration is increasing, and thus the size of TFT is decreasing. When the scale of manufacturing technique of the silicon-based transistor reaches to 0.13 ?m, the thickness of dielectric layer of silica?SiO₂? will reduce to 2.5 nm. When the thickness of silicon dioxide?SiO₂? in TFT is decreased to 2 nm, the current tunneling effect becomes serious. There are two ways to solve this problem: changing the structure of TFT or finding an alternative high-k gate dielectric material. Thin film transistor?TFT? is a kind of field effect transistor, which is the core device of liquid crystal display?LCD? and organic light emitting display?OLED?. In this paper, we will research the physical property and annealing effects of solution-processed high k material in TFT.Among these high-k materials, hafnium oxide?HfOx? is regarded as a good candidate due to its high dielectric constant of 25, wide band gap of 5.8 e V. In this work, HfOx dielectric films were fabricated by using spin-coating method. The properties of HfOx thin films were studied by atomic force microscope?AFM?, fourier transform infrared spectrum?FT-IR? and X-ray photoelectron spectroscopy?XPS?. The annealing effects on the microstructural and electrical properties of HfOx thin films were studied. The HfOx thin film annealed at 500 ? exhibited the best insulating performance with a current density of 10^-9 A/cm² at an electric field of 4.5 MV/cm. In order to demonstrate the possible application of HfOx thin films in transistors, the indium-zinc oxide?IZO? channel layer was fabricated by using magnetron sputtering at room temperature. The IZO TFT based on 500 ?-annealed HfOx can be operated under an operation voltage of 5 V, with a high fieldeffect mobility of 36.9 cm²/V s, a threshold voltage of 1.8 V, a subthreshold swing of 0.38 V/dec, and an on/off current ratio of 109. At last, we studied the HfAlOx films.The results demonstrate that HfOx thin film prepared by using spin-coating method is a promising gate dielectric candidate for cheap and high-performance oxide electronic devices.