Back-Channel-Etched IGZO TFTs With Cu-Based Multilayer Electrodes Using MoAl Alloy and MoMn Alloy as Buffer Layers

Abstract

We report high-performance IGZO TFTs with MoAl/Cu/MoAl and MoMn/Cu/MoMn three-layer electrodes, where MoAl or MoMn alloy is used as the buffer layer. The multilayer electrode has good electrical properties and can effectively prevent the oxidation and diffusion of the middle Cu layer. In addition, the multilayer electrode can be etched in a PAN etchant solution and match the etching rate with Cu. Based on these MoAl/Cu/MoAl and MoMn/Cu/MoMn electrodes, vacuum-processed IGZO TFTs exhibit a turn-on voltage of 0 V, an on-off ratio of 10⁹, and a mobility of 10.7 cm² V⁻¹ s⁻¹ after annealing at 115 °C in N₂. Under the gate bias stress test, devices with MoMn electrodes, which exhibit a small threshold voltage shift, show better performance than those with MoAl electrodes. The presented studies may provide another option for the Cu buffer layer.