Method for producing high-purity lanthanum, high-purity lanthanum, sputtering target formed from high-purity lanthanum, and metal gate film having highy-purity lanthanum as main component

摘要

The present invention addresses the problem of providing a technique capable of efficiently and stably providing a method for producing high-purity lanthanum, the method characterized in that: a crude lanthanum oxide starting material having a purity of 2N-3N, excluding gas components, is used; the material is subjected to molten salt electrolysis at a bath temperature of 450-700° C. to produce lanthanum crystals; the lanthanum crystals are subsequently desalted: and electron beam melting is then performed to remove volatile substances. The present invention also addresses the problem of providing a technique capable of efficiently and stably providing high-purity lanthanum, high-purity lanthanum itself, a sputtering target formed from high-purity material lanthanum; and a thin film for metal gates that has high purity lanthanum as the main component.

主权项

1. A method for producing high-purity lanthanum comprising the steps of:
using a crude lanthanum raw material having a purity of 2 to 3N, excluding gas components, as the starting material; performing molten salt electrolysis at a bath temperature of 450 to 700° C. to produce lanthanum crystals; desalting the lanthanum crystals by vacuum heating at a temperature of no more than 850° C. using a desalting furnace and separating metal and salt by making use of the difference in the vapor pressures; and thereafter performing electron beam melting to remove volatile substances.