Improved stability of amorphous InGaZnO₄ thin-film transistors under negative bias illumination stress with the incorporation of fluorine passivation and metal shielding lines

The instability phenomenon under negative bias illumination stress (NBIS) remains a major challenge for the application of amorphous indium gallium zinc oxide (a-IGZO) thin-film transistors (TFTs) in active-matrix displays. In this paper, we employ fluorine plasma treatment and a segmented metal cover line approach to enhance the stability of elevated metal metal-oxide (EMMO) a-IGZO TFTs under NBIS. At room temperature, after 15 minutes of fluorine treatment, ΔV_ON decreases from 5.53 V to 2.02 V. This improvement is mainly attributed to the fact that fluorine atoms fill the ionized oxygen vacancies in a-IGZO, thereby reducing the density of defect states in the channel. Further adding 2.0 μm wide metal-covered wires reduces the ΔV_ON to 0.35 V. Under 80 °C NBIS, the ΔV_ON is limited to 3.79 V. This improvement is mainly attributed to the light-shielding effect of the metal lines and the passivation of oxygen vacancies by fluorine, thereby enhancing device stability under NBIS.