Method for Storing Target Comprising Rare Earth Metal or Oxide Thereof

Abstract

Provided is a method for storing a target comprising a rare earth metal or oxide thereof, wherein oxide of the same rare earth metal as the material of the rare earth metal or its oxide target to be stored is introduced as a desiccant into a container or a film-type seal for storing the target, and the target is stored by sealing the storage container or the film-type seal. This invention aims to provide technology for enabling the long-term storage of a target by devising the method for storing a target comprising a rare earth metal or oxide thereof, and thereby inhibiting the pulverization of the target caused by the oxidation and hydroxylation of such target due to the ingress of air.

Description

TECHNICAL FIELD[0001]The present invention relates to a method for storing a target comprising a rare earth metal or oxide thereof that is easily pulverized due to oxidation or hydroxylation.BACKGROUND ART[0002]Rare earth metals are contained in the earth's crust as a mixed composite oxide. Rare-earth elements are so called because they are separated from relatively rare minerals, but they are not that rare in light of the overall earth's crust. In recent years, rare earth metals are attracting attention as an electronic material, and research and development for using rare earth metals are being promoted.[0003]Among the rare earth metals, lanthanum (La) is attracting particular attention. To briefly introduce lanthanum, lanthanum is a white metal having an atomic number of 57 and an atomic weight of 138.9, and comprises a double hexagonal close-packed structure at normal temperature. Lanthanum has a melting point of 921° C., boiling point of 3500° C., and density of 6.15 g / cm3, its...

AI Technical Summary

Benefits of technology

[0031]When encapsulating and storing a conventional target comprising a rare earth metal or oxide thereof in a hermetic container or with a plastic film, if it goes unattended for a long time, it will react with oxygen and moisture and become covered with white hydroxide powder, and there is a problem in that normal sputtering cannot be performed. Nevertheless, the target that is stored in a storage container or a film-type seal according to the present invention yields a significant effect of being able to avoid the foregoing problems.

Problems solved by technology

A rare earth metal such as lanthanum is a material in which high purification is difficult to achieve since it is easily oxidized during the refining process.

In addition, if a rare earth metal such as lanthanum is left in the atmosphere, there is a problem in that the handling thereof is difficult since it will become oxidized and tarnished in a short time.

In recent years, thinning of a gate insulator film is being demanded in the next-generation MOSFET, but with the SiO2 that has been conventionally used as the gate insulator film, the leak current increases due to the tunnel effect, and normal operation is becoming difficult.

Nevertheless, even if a lanthanum sputtering target is prepared, as described above, it becomes oxidized in a short time in the atmosphere.

However, with a lanthanum sputtering target, the oxide layer becomes thick, and deterioration of the electrical conductivity will occur and thereby cause defective sputtering.

In addition, if the lanthanum sputtering target is left in the atmosphere for a long time, it reacts with the moisture in the air to become covered with white hydroxide powder and ultimately become pulverized, and it may even cause a problem of not allowing normal sputtering to be performed.

However, there is a problem in that the cleaning of the target itself is difficult due to its reactivity with oxygen, moisture and carbon dioxide.

However, even in a state where the target is vacuum packed, since pulverization caused by oxidation or hydroxylation will progress even with a small amount of moisture that penetrates the used film, it was difficult to store the sputtering target in enabled condition for a long time.

Nevertheless, since the foregoing Documents disclose that the target is encapsulated with a resin lid or a resin film, they are insufficient as a method for storing a target comprising a rare earth metal or oxide thereof.

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