Method for Fabricating Amorphous Indium-Zinc-Oxide Thin-Film Transistors With Copper Source and Drain Electrodes

We revealed a novel method to fabricate amorphous indium-zinc-oxide (a-IZO) thin-film transistors (TFTs) with inverted staggered back-channel-etch structure and copper (Cu) source/drain (S/D) electrodes. In particular, a gray-tone mask was used to define the S/D electrodes and active layer. The a-IZO layer acted not only as the active layer but also as the adhesive layer of Cu electrodes due to the good adhesion between Cu and a-IZO films. The presented TFTs exhibited a high saturated mobility of 12.2 cm²/Vs, a threshold voltage of -0.4 V, and a low subthreshold swing of 0.22 V/decade. The good electrical performance and reliability were attributed to the good contact property between Cu electrodes and a-IZO layer and very little Cu atoms diffusing into the channel layer.