37.2: Development of High Performance Oxide TFTs Using Back‐Channel‐Etch Structure With Copper Electrodes

In this paper, back‐channel‐etch structure TFTs with copper electrodes were manufactured using Indium‐Gallium‐Zinc oxide (IGZO) and Lanthanide rare earth element doped Indium‐Zinc oxide (Ln‐IZO) as the active layer. After researching the influence of different copper etchants on oxide films and device performance, we recommended fluorine‐free copper etchant. Furthermore, the application of an heavily doped Ln‐IZO with less indium content as a barrier layer covering the lightly doped Ln‐IZO layer exhibits stronger tolerance to copper etchants. With this dual‐active‐layer structure , our devices performed even higher mobility (>15 cm2/Vs).