When the size of display panel increased, the RC delay of TFTs became serious.In order to solve this problem, it is necessary to incorporate a high dielectric (high-k) material used as the gate oxide can increase the gate oxide capacitance Co, which can induce a higher drain current and higher aperture ratio. In this study, titanium silicon oxide films were grown on amorphous silicon and poly-crystal silicon by liquid phase deposition, the addition of NH4OH in the growth solution can control the PH value and prevent the amorphous and poly-crystalline silicon over etching by HF. The physical and chemical properties of titanium silicon oxide film by means of several measuring instruments, including Fourier transform infrared spectrometer (FTIR), and X-Ray diffractometer (XRD). An Al/titanium silicon oxide/a-Si or poly-Si/Si metal-oxide-semiconductor (MOS) capacitor structure was used for the electrical measurements. After oxygen and nitrogen annealing, the leakage current is improved due to the reduction of the oxygen vacancy of titanium silicon oxide film. However, the electrical characteristics can be further improved by the postmetallization annealing treatment especially under the negative electric field. Post-metallization annealing (PMA) is to use the reaction between the aluminum contact and hydroxyl groups existed on oxide surface to form active hydrogen and diffuse through the oxide to passivate the oxide traps. Therefore, titanium silicon oxide film which treated by PMA with higher dielectric constant and lower leakage current can be obtained.

The area of advanced gate dielectrics has gained considerable attention recently because semiconductor technology roadmaps predict for less than 2 nm equivalent oxide thickness (EOT) for next 10 years, and there are significant leakage current and reliability concerns for oxy-nitride in this regime. So it¡¦s an important business to use alternate high-k dielectrics instead of oxy-nitride. Titanium silicon oxide shows a low leakage current with a high dielectric constant for dielectric applications. Besides, barium doping can create additional oxygen vacancies that can enhance dielectric constant. In this study, we prepared barium doped titanium silicon by liquid phase deposition which is a novel material considered to have intermediate properties of silicon dioxide and titanium dioxide. From several characteristic measurements, we found that barium doped titanium silicon oxide with exhibiting higher dielectric constant, low leakage current and well interface state which is very promising candidates to instead of titanium silicon oxide. The physical and chemical properties of barium doped titanium silicon oxide films by means of several measuring instruments, including Fourier transform infrared spectrometer (FTIR), secondary ion spectrometer (SIMS), and X-Ray diffractometer (XRD). An Al / Ba doped titanium silicon oxide / Si metal-oxide-semiconductor (MOS) capacitor structure was used for the electrical measurements. The static dielectric constant of the O2-annealed barium doped titanium silicon oxide film can reach about 22.3. In addition, it has well leakage current density of 2.6 ¡Ñ 10-6 A/cm2 at 5 MV/cm with the equivalent oxide thickness 1.27 nm (optical thickness of 7.3 nm). It has high potential for dielectric applications.

High dielectric constant barium doped titanium silicon oxide films with equivalent oxide thickness below 1 nm can be prepared by liquid phase deposition. We learn from this research that the deposition rate of titanium silicon oxide films can be much enhanced by nitric acid incorporation, and the dielectric constant of materials can be increased by the dipole polarization from barium. The key parameter for the deposition rate, refractive index, and the dielectric constant of barium doped titanium silicon oxide is the molarity of barium nitrate. The electrical properties can be improved effectively by thermal annealing treatments. The optimum equivalent oxide thickness of barium doped titanium silicon oxide thin film is 0.9 nm with the optical thickness of 7.4 nm. The high dielectric constant can reach 31.9 and the leakage current density is 5 ¡Ñ 10-6 A/cm2 at the electrical field intensity of 5 MV/cm, which has high potential application for the next generation MOSFET.