STUDY ON FABRICATION PROCESS AND PROPERTIES OF AMORPHOUS INGAZNO THIN FILM TRANSISTOR

The present study reports on the fabrication of amorphous InGaZnO (a-IGZO) thin films on silicon oxide substrates using radio-frequency magnetron sputtering technique, and investigates their characteristics under different conditions. Subsequently, a-IGZO thin-film transistors (a-IGZO TFT) were prepared and their electrical properties were studied in relation to the effects of sputtering atmosphere, active layer thickness, and annealing process. The experimental findings demonstrate that, when using a sputtering power of 50W, the performance of the device can be improved by introducing supplemental oxygen into the sputtering process, which effectively mitigates the deep-level oxygen vacancy defects in the material. However, an excessive concentration of oxygen may give rise to an increase in the number of acceptor defects, such as adsorbed oxygen, which promotes carrier scattering. Based on our investigation, we determined that the device exhibited optimal performance when the argon-oxygen ratio was maintained at Ar∶O2=24∶1.2. Secondly, optimal performance of the device is achieved by controlling the thickness of the active layer within the range of 40~50nm, with the film properties peaking at a thickness of 40nm. Finally, the application of high-temperature annealing process serves to alleviate the defects of the film, while also effectively eliminating any internal stresses that may exist within the film. In comparison with nitrogen annealing conditions, annealing a-IGZO films under an air environment leads to superior electrical properties. Specifically, annealing a 40nm-thick film at 400℃ for 30 minutes in air resulted in the optimal performance of the a-IGZO TFT device, with a recorded mobility of 15.43cm²/(V·s), a threshold voltage of 13.09 V, and a current switching ratio of 7.3×10⁸. These findings establish a solid foundation for future endeavors towards the preparation of wafer-level high-mobility a-IGZO TFTs.