Manufacturing of Large-Scale Cold-Sprayed Ta Target Material and Its Sputtering Property

Abstract

The manufacture of high-purity Ta sputtering targets suffers from high processing costs and long manufacturing times because of the high melting point and oxygen affinity. This calls for new process that can reduce the processing cost and manufacturing time. In this study, large-scale (21 × 21 × 0.4 cm3) Ta sputtering material was manufactured using cold spraying. The manufactured cold-sprayed Ta target material underwent actual sputtering to evaluate its properties. Pure Ta powder was used for the cold spray, and the sputtering target material was manufactured under suitable process conditions. The manufactured target material was composed of α-Ta phase that was identical to the powder feedstock. Microstructural observation of the target material confirmed that it was very dense with almost no pores. Vacuum sputtering was performed using two sputtering conditions, viz. 500 W/3 mTorr and 1 kW/3 mTorr. Atomic force microscopy (AFM), transmission electron microscopy (TEM), and energy-dispersive x-ray spectroscopy (EDS) mapping analyses were performed on the sputtered thin layers obtained. To identify whether small amounts of impurities were present in the sputtered thin layers, secondary-ion mass spectrometry (SIMS) was performed. In both sputtered thin layers, small amounts of oxygen and impurities were found along with Ta element. Based on these results, this study explored the possibility of manufacturing a target material using cold spraying and its sputtering applications.