| abstract |
An oxide sintered object which comprises a composite oxide of lanthanum and hafnium, characterized in that the amount of the hafnium contained in the sintered object is equivalent to or larger than that of the lanthanum. A process for producing a sintered object of an oxide of lanthanum and hafnium is provided which is characterized by using an La2(CO3)3 powder and an HfO2 powder as raw-material powders, mixing the powders so that the Hf/La molar ratio becomes 1-1.2, thereafter heating the powder mixture in the air to conduct synthesis, subsequently pulverizing the synthesized material into a powder, and then hot-pressing the synthesis powder to form a sintered object. Lanthanum metal combines rapidly with oxygen and disintegrates, while lanthanum oxide combines with water to form the hydroxide and changes to a powder. Both lanthanum metal and lanthanum oxide have hence had a problem that long-term storage is difficult and a sputtering target, even when produced, cannot be actually used. In view of this, the stable lanthanum-containing oxide sintered object comprising an oxide of lanthanum (La) and hafnium (Hf) is provided. A lanthanum-containing oxide sputtering target especially suitable for use in forming a high-k gate insulating film is provided. |