| 摘要 |
The present invention addresses the problem of providing: high-purity yttrium characterized by having a purity, in terms of the purity of the yttrium from which the rare-earth elements and gas components have been excluded, of 5 N or higher and having Al, Fe, and Cu contents of 1 wt. ppm or less each; a high-purity yttrium sputtering target; a process for producing the high-purity yttrium, the process being characterized by subjecting a crude yttrium oxide, as a raw material, that has a purity, in terms of the purity of the crude yttrium oxide from which the gas components have been excluded, of 4 N or less to molten-salt electrolysis at a bath temperature of 500-800ºC to obtain yttrium crystals, subsequently subjecting the yttrium crystals to desalting, water washing, and drying, and thereafter melting the crystals with electron beams to remove volatile substances therefrom and thereby regulate the purity, in terms of the purity of the yttrium from which the rare-earth elements and gas components have been excluded, to 5 N or higher; and methods which make it possible to efficiently and stably provide the sputtering target, which is constituted of high-purity yttrium, and a metal-gate thin film which comprises high-purity yttrium as the main component. |
