Insights into the Properties of IGZO Films and Thin-Film Transistors Fabricated by Radio Frequency and High-Power Impulse Magnetron Sputtering

Abstract An amorphous indium-gallium-zinc-oxide (a-IGZO) film is a promising candidate for high performance TFT devices. In this study, the a-IGZO films were fabricated using radio frequency magnetron sputtering (RFMS) and high-power impulse magnetron sputtering (HiPIMS). The detailed IGZO film deposition mechanism under RFMS and HiPIMS has been proposed and elaborated, respectively. It is verified by in situ optical emission spectroscopy used to monitor the excited plasma species during the deposition process. The overall plasma intensity under RFMS is higher than that of HiPIMS, especially for the ratio of excited neutral radicals, leading to a bigger deposition rate. By contrast, the ratio of positive charged ions under HiPIMS is distinctly higher than that of RFMS. The atomic ratio of RF-IGZO film is closer to the target and shows higher electron mobility. In comparison, the atomic ratio of HiPIMS-IGZO film is slightly deviates from target. The HiPIMS-IGZO film is more compact and smooth with higher film density, but lower electron mobility. Hence, it may be necessary to tune the target atomic ratio to obtain the optimal atomic ratios of HiPIMS-IGZO film. This work may provide a unique perspective for the achievement of superior IGZO film and TFT device using HiPIMS.