High performance a-InZnSnO thin-film transistor with a self-diffusion-barrier formable copper contact

A low resistivity copper (Cu) film was used as a source/drain contact layer to fabricate high performance amorphous In-Zn-Sn-O (a-IZTO) thin-film transistors (TFTs). The calcium (Ca)-doped Cu films greatly simplified the conventional Cu/diffusion barrier stack structure and process, which allowed the production of promising a-IZTO TFTs with a saturation mobility of 22.8 cm2/Vs and an ION/OFF ratio of 108. Furthermore, the a-IZTO TFTs with the Ca-doped Cu contact exhibited better gate bias thermal stress-induced stabilities than those with the pure Cu contact. This was attributed to the effective formation of a self-diffusion CuOx barrier at the Cu/IZTO interfaces.