Study on Ozonated Solution Oxidation of Phosphorus Doped Hydrogenated Amorphous Silicon Surface for Cu–Mn Alloy Based Electrodes in Thin Film Transistor

For next generation Cu–Mn alloy based interconnects in thin film transistor liquid crystal displays (TFT-LCDs), we propose the use of an ozonated solution as a promising oxidation pretreatment of phosphorus doped hydrogenated amorphous silicon (n+a-Si:H) surface for the self-formation of Mn complex oxide layers. We have investigated the electrical characteristics of TFTs having Cu/Cu–Mn alloy bilayer electrodes with/without ozonated solution oxidation and those having conventional Cr–Mo single layer electrodes. TFTs having Cu/Cu–Mn alloy electrodes oxidized with ozonated solution exhibit very similar transfer characteristics to those of TFTs with conventional material electrodes; however, they also show increases in threshold voltage (Vth) and subthreshold swing (SS) as well as slightly reduced electron mobility and on-current. We have concluded that partial and shallow Cu-diffusion into a n+a-Si:H layer is the most likely reason for the degraded TFT electrical properties.