Purification of sputtering target metals for high-k insulator films of MOSFET devices

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Purification of Hf, Zr, Ti, La and Ce, needed as the sputtering target metals for the advanced electronic devices, was examined by means of thermal plasma arc techniques. For purification of Hf, Zr and Ti, hydrogen plasma arc melting (HPAM) was used and, then, their high purity metals were obtained by the remarkable reduction of many volatile metallic impurities like Fe, Al, and Cu during HPAM under atmospheric pressure. On the other hand, for purification of La and Ce, plasma arc zone melting (PZM) was applied and, then, high purity both metals were prepared by the excellent segregation of several metallic impurities like Fe and Al and, furthermore, the vaporization reduction of volatile impurities like Ca and Mn during PZM of La and Ce rods.