Preparation of IGZO sputtering target and its applications to thin-film transistor devices

Nano-scale In₂O₃, Ga₂O₃ and ZnO powder mixture prepared by a hybrid process of chemical dispersion and mechanical grinding was adopted for the In–Ga–Zn–O (IGZO) sputtering target fabrication. A pressure-less sintering at 1300 °C for 6 h yielded the target containing sole InGaZnO₄ phase with relative density as high as 93%. Consequently, the thin-film transistor (TFT) devices containing amorphous IGZO channels were prepared by using the self-prepared target and the electrical measurements indicated the TFT subjected to a post annealing at 300 °C exhibits the best device performance with the saturation mobility = 14.7 cm²/V s, threshold voltage = 0.57 V, subthreshold gate swing = 0.45 V/decade and on/off ratio = 10⁸. Capacitance–voltage measurement indicated that post annealing effectively suppresses the interfacial traps density at the IGZO/SiO₂ interface and thus enhances the electrical performance of TFT.