JP2601676B2 - Method for producing thin-film oxide superconductor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial application field) The present invention relates to a thin film oxide superconductor which is used when a thin film oxide superconductor is formed by sputtering on a substrate. It relates to a manufacturing method.

2. Description of the Related Art It has long been known that when a certain metal or alloy is cooled to a temperature near zero in absolute temperature, the electric resistance of the metal or alloy becomes zero. Recently, an oxide having a perovskite structure has been known. Are also reported to exhibit such superconducting properties.

Therefore, this kind of oxide is sputtered on a substrate and used as a superconductor.

Conventionally, when a thin-film oxide superconductor is formed by sputtering a Y-Ba-Cu-O-based oxide superconductor composition material on a substrate, a part of the Cu composition is considered in consideration of evaporation. ,
Usually, a sputtering target having a higher Cu composition than the stoichiometric composition has been used.

(Problems to be Solved by the Invention) In the above-described conventional method, since a sputtering target having a large Cu composition needs to be used, this target is made of Cu.
Depending on the composition, it became an insulator or a semiconductor, and was not suitable for DC sputtering.

Further, in this case, since a part of the Cu composition evaporates, there is a disadvantage that the properties as an oxide superconductor are significantly impaired.

The present invention has been made in order to solve the above-mentioned problems, the application of DC sputtering can be performed without hindrance, and a thin film oxide superconductor capable of obtaining a stoichiometric oxide superconductor It is intended to provide a manufacturing method.

[Constitution of the Invention] (Means for Solving the Problems) A first invention relates to a method for producing a thin film oxide superconductor, wherein a Y-Ba-Cu-O-based oxide superconductor composition material is used.
With respect to parts by weight, a fine powder of Cu is added in an amount of 5 to 30 parts by weight, and the mixture is finely mixed to form a sputtering target. did.

In a second aspect, a fine powder of Cu and at least one of fine powders of Ag and Au are combined with respect to 100 parts by weight of the Y-Ba-Cu-O-based oxide superconductor composition material. 5 to 30 parts by weight were added and finely mixed to form a sputtering target, and the sputtering gate was used to form a thin film superconductor by sputtering on a substrate.

(Action) In the first invention, 5 to 30 parts by weight of a fine powder of Cu is added to 100 parts by weight of the Y-Ba-Cu-O-based oxide superconductor composition material, and this is finely divided. Since the sputtering is performed on the substrate using an oxide superconductor sputtering target mixed with, especially during the sputtering, Cu is present as a fine metal powder, and since Cu is present in a larger amount than the stoichiometric composition, the AC The superconductor is formed as an oxide superconductor on the substrate not only by sputtering but also by DC sputtering without becoming an insulator or a semiconductor.

In addition, the presence of the Cu fine metal powder improves the thermal power ratio of the target, and suppresses the occurrence of cracks due to thermal strain.

In the second invention, Cu fine powder and at least one of Ag and Au fine powders are mixed with 100 parts by weight of the Y-Ba-Cu-O-based oxide superconductor composition material. In addition, 5 to 30 parts by weight, using an oxide superconductor sputtering target that is finely mixed, it is to be sputtered on the substrate, especially during sputtering Cu is present as a fine metal powder, and Cu Is present in excess of the stoichiometric composition, and the presence of at least one or more fine powders of Ag and Au improves the conductivity of the sputtering target. The superconductor is formed as an oxide superconductor on the substrate by sputtering without becoming an insulator or a semiconductor.

(Example) Hereinafter, an example is described.

First, less than 5 parts by weight (4 parts by weight) of Cu fine powder is added to 100 parts by weight of Y-Ba-Cu-O-based oxide superconductor powder, and these are mixed to form a sputtering target. did.

In this state, sputtering was performed on the substrate. In this case, however, the effect of the addition of Cu became uncertain and sometimes resulted in an insulator or a semiconductor.

Further, the improvement of the thermal conductivity was not sufficient, and sometimes cracks occurred in the target.

On the other hand, the same treatment as described above was performed with the amount of the fine powder of Cu being 30 parts by weight or more (55 and 65 parts by weight). in this case
On the contrary, depending on the conductor characteristics of the fine metal powder of Cu, the conductor may be a conductor in any case, the thermal conductivity has been improved, and the occurrence of cracks has been suppressed. Could not be obtained.

As a result, it was found that the optimal amount of the Cu fine powder was 5 to 30 parts by weight based on 100 parts by weight of the Y-Ba-Cu-O-based oxide superconductor powder.

Next, based on 100 parts by weight of the Y-Ba-Cu-O-based oxide superconductor powder, the total amount of the fine powder of Cu and the fine powder of Ag is less than 5 parts by weight (Cu 3, Ag 1, (Total 4 parts by weight) were added and mixed to form a sputtering target.

In this state, sputtering was performed on the substrate. In this case, however, it was found that the effect of adding the fine powder of Cu and the fine powder of Ag became uncertain and sometimes became an insulator.

On the other hand, the same processing as described above was performed with the total amount of the Cu fine powder and the Ag fine powder being 30 parts by weight or more (55 and 65 parts by weight).

In this case, depending on the conductor properties of the fine powder of Cu and Ag,
Contrary to the above, the conductor sometimes became a conductor in each case.

Note that Au was used instead of Ag, but the same results as in the case of Ag were obtained.

As a result, Cu fine powder and at least one of Ag and Au
It has been found that the optimal amount of addition to the seed fine powder is 5 to 30 parts by weight based on 100 parts by weight of the Y-Ba-Cu-O-based oxide superconductor powder.

[Effects of the Invention] As described above, according to the present invention, the sputtering target does not become an insulator or a semiconductor even by DC sputtering, and it becomes possible to obtain an oxide superconductor according to stoichiometry. .

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification number Agency reference number FI Technical display location H01L 39/24 ZAA H01L 39/24 ZAAB

Claims (2)

(57) [Claims] 1. A sputtering target is prepared by adding 5 to 30 parts by weight of a fine powder of Cu to 100 parts by weight of a Y-Ba-Cu-O-based oxide superconductor composition material and mixing them finely. A method of manufacturing a thin film oxide superconductor, comprising forming a thin film superconductor by sputtering on a substrate using the sputtering gate. 2. A fine powder of Cu and at least one of fine powders of Ag, Au and Pt are mixed with 100 parts by weight of a Y-Ba-Cu-O-based oxide superconductor composition material. A sputtering target is formed by adding 5 to 30 parts by weight of the total amount and mixing them finely, and a thin film superconductor is formed by sputtering on a substrate using the sputtering target. Conductor manufacturing method.