| abstract |
A rare earth element and a gaseous component, wherein the purity is not less than 5N, and each of Al, Fe, Cu and Ta is not more than 1 wtppm, W is not more than 10 wtppm, carbon is not more than 150 wtppm, alkali metals and alkaline earth metals are each not more than 1 wtppm, And the radioactive elements U and Th are each 10 wt ppb or less. A method for highly purifying erbium which has a high vapor pressure and is difficult to purify in a molten state, and a method for efficiently and stably providing a high-purity erbium, a sputtering target made of erbium of high purity and a metal gate thin film containing erbium as a main component And to provide a technology that can be used. |