Highly pure lanthanum, sputtering target comprising highly pure lanthanum, and metal gate film mainly composed of highly pure lanthanum

摘要

Provided are high-purity lanthanum, wherein the purity excluding rare-earth elements and gas components is 4N or higher, and amounts of aluminum, iron and copper in the lanthanum are respectively 100wtppm or less; as well as high-purity lanthanum, wherein the purity excluding rare-earth elements and gas components is 4N or higher, amounts of aluminum, iron and copper in the lanthanum are respectively 100wtppm or less, oxygen content is 1500wtppm or less, elements of alkali metals and alkali earth metals are respectively 1wtppm or less, elements of transition metals and high-melting-point metals other than those above are respectively 10wtppm or less, and radioactive elements are respectively 10wtppb or less. The invention aims to provide technology capable of efficiently and stably providing high-purity lanthanum, a sputtering target comprising high-purity lanthanum, and a thin film for metal gate mainly comprising high-purity lanthanum.