Self-aligned indium-gallium-zinc oxide thin-film transistors with SiNx/SiO2/SiNx/SiO2 passivation layers

Self-aligned top-gate amorphous indium-gallium-zinc oxide (a-IGZO) thin-film transistors (TFTs) with SiNx/SiO2/SiNx/SiO2 passivation layers are developed in this paper. The resulting a-IGZO TFT exhibits high reliability against bias stress and good electrical performance including field-effect mobility of 5 cm2/Vs, threshold voltage of 2.5 V, subthreshold swing of 0.63 V/decade, and on/off current ratio of 5 × 106. With scaling down of the channel length, good characteristics are also obtained with a small shift of the threshold voltage and no degradation of subthreshold swing. The proposed a-IGZO TFTs in this paper can act as driving devices in the next generation flat panel displays.