Method for Manufacturing High-Purity Erbium, High-Purity Erbium, Sputtering Target Composed of High-Purity Erbium, and Metal Gate Film having High-Purity Erbium as Main Component

Abstract

Provided are a method for manufacturing high-purity erbium, wherein crude erbium oxide is mixed with reducing metal, erbium is reduced and distilled by heating the mixture in a vacuum, and the distillate is melted in an inert atmosphere to obtain high-purity erbium; and high-purity erbium, wherein the purity excluding rare-earth elements and gas components is 4 N or higher and the oxygen content is 200 wtppm or less. An object of this invention is to provide a method of highly purifying erbium, which has a high vapor pressure and is difficult to be refined in a molten metal state, as well as technology for efficiently and stably providing high-purity erbium obtained with the foregoing method, a sputtering target composed of high-purity erbium, and a metal gate film having high-purity erbium as a main component.

1 . A method for manufacturing high-purity erbium, wherein erbium oxide is mixed with reducing metal, the mixture is thereafter heated in a vacuum and distilled while being reduced to metal erbium, and the distillate is melted in an inert atmosphere to obtain high-purity erbium in which the purity excluding rare-earth elements and gas components is 4 N or higher, oxygen content is 200 wtppm or less, elements of alkali metals are respectively 10 wtppm or less, elements of transition metals are respectively 100 wtppm or less, and radioactive elements are respectively 10 wtppb or less. 
     
     
         2 . The method for manufacturing high-purity erbium according to  claim 1 , wherein the mixture is heated to a temperature of 1500 to 2500° C. during the reduction and distillation of erbium. 
     
     
         3 . The method for manufacturing high-purity erbium according to  claim 2 , wherein erbium oxide having a purity of 3 N or less is used as the raw material, and this is refined to obtain high-purity erbium having a purity of 4 N or higher. 
     
     
         4 . (canceled) 
     
     
         5 . High-purity erbium, wherein the purity excluding rare-earth elements and gas components is 4 N or higher, oxygen content is 200 wtppm or less, elements of alkali metals are respectively 10 wtppm or less, elements of transition metals are respectively 100 wtppm or less, and radioactive elements are respectively 10 wtppb or less. 
     
     
         6 . (canceled) 
     
     
         7 . A high-purity erbium sputtering target made of the high-purity erbium according to  claim 5 . 
     
     
         8 . A metal gate film having high-purity erbium as a main component, made of the high-purity erbium according to  claim 5 . 
     
     
         9 . The high-purity erbium according to  claim 5 , wherein the alpha dose of the high-purity erbium is 0.01 cph/cm 2  or less. 
     
     
         10 . A high-purity erbium sputtering target made of the high-purity erbium according to  claim 9 . 
     
     
         11 . A metal gate film having high-purity erbium as a main component, made of the high-purity erbium according to  claim 9 . 
     
     
         12 . The method for manufacturing high-purity erbium according to  claim 3 , wherein the alpha dose of the high purity erbium is 0.01 cph/cm 2  or less. 
     
     
         13 . The method for manufacturing high-purity erbium according to  claim 1 , wherein erbium oxide having a purity of 3 N or less is used as the raw material, and this is refined to obtain high-purity erbium having a purity of 4 N or higher. 
     
     
         14 . The method for manufacturing high-purity erbium according to  claim 1 , wherein the alpha dose of the high purity erbium is 0.01 cph/cm 2  or less.