Low-cost Xe sputtering of amorphous In-Ga-Zn-O thin-film transistors by rotation magnet sputtering incorporating a Xe recycle-and-supply system

A Xe recycle-and-supply system was incorporated into a dual-target rotation magnet sputtering (DT-RMS) process to fabricate amorphous In-Ga-Zn-O (a-IGZO) thin-film transistors (TFTs). DT-RMS is an upgraded version of the previously reported single-target rotation magnet sputtering system [Goto et al., J. Vac. Sci. Technol. A 27, 653 (2009)] designed to expand deposition area. In DT-RMS, multiple moving plasma loops are excited at the dual-target surface. These plasma loops work to homogenize the properties of the films deposited on the substrates, with time-averaged homogenization of the plasma parameters at the substrate. As a result, film thicknesses and uniform distributions of the a-IGZO-film properties were obtained at an appropriate target-substrate distance. In this configuration, the Xe-sputtered a-IGZO TFTs exhibited higher field-effect mobilities than conventional Ar-sputtered TFTs. When using the recycled Xe supplied from the Xe recycle-and-supply system, the field-effect mobility value was the same as for fresh-Xe sputtered TFTs, demonstrating the technique's potential as a low-cost alternative for providing the flat panel display industry with Xe.