JPH01226183A - Manufacture of ceramic superconductor - Google Patents

Abstract

PURPOSE:To obtain a fine pattern without deteriorating the characteristics of a superconductor by forming the fine pattern of a thin film material of a second material on a substrate of a first material and depositing a ceramic superconductor on the pattern. CONSTITUTION:A ZrO2 thin film containing Y is deposited on a sapphire (Al2O3 single crystal) substrate 1 in about 1000Angstrom thickness using rf magnetron sputtering, and a fine pattern 2 of ZrO2 containing Y is formed by ordinary photolithography and dry etching. Then, an about 1mum thickness oxide thin film 3 of a composition ratio Y:Ba:Cu=1:2:3 is formed on the fine pattern by sputtering a Y-Ba-Cu oxide target with Ar+O2 gas at a substrate temperature of 200 deg.C by making use of rf magnetron sputtering. The Y-Ba-Cu oxide film formed on the ZrO2 surface containing Y has electric resistance which allows superconduction starts at about 92 K and which becomes zero at about 82 K.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to a method for producing a ceramic superconductor that can be used for superconducting elements such as a Josephson element and a magnetic detection element, and more specifically relates to a method for producing a ceramic superconductor that can be used for superconducting elements such as Josephson elements and magnetic detection elements. The present invention relates to a method for producing a ceramic superconductor that allows a fine ceramic superconductor pattern to be obtained without processing.

<Prior Art> Conventionally, wet etching using phosphoric acid, nitric acid, etc., or dry etching using chlorine gas plasma has been used as a method for processing ceramic superconducting thin films into fine patterns.

<Problems to be solved by the invention> However, the processing method of ceramic superconductors using wet or dry etching described above causes deterioration of the properties of the superconductors (
It is insufficient in that the intention to generate (critical temperature, critical current) and the stability of characteristics after processing are poor.

This is thought to be caused by compositional deviations, oxygen removal, etc. during processing. The present invention was devised in view of the above points, and it is possible to
The object of the present invention is to provide a method for manufacturing a ceramic superconductor that can obtain a ceramic superconductor pattern.

<Means for Solving the Problems> In order to achieve the above objectives, the method for manufacturing a ceramic superconductor of the present invention includes forming a fine pattern of a thin film material made of a second material on a substrate made of a first material. a step of forming;
Thereafter, the method includes a step of depositing a ceramic superconductor as a film of the first or second material. The ceramic film deposited on the ceramic film is made of a material that cannot become a superconductor, and as the other material of the first or second material, the material has good compatibility with the ceramic superconductor and the material is The ceramic film deposited on the ceramic film is made of a material that can become a superconductor.

That is, the present invention provides a substrate made of a material that is poorly matched to the ceramic superconductor and prevents a ceramic film deposited on the substrate from becoming a superconductor. Often, a fine pattern of a thin film material made of a material such that a ceramic film deposited on this material can become a superconductor is formed, and the above-mentioned ceramic superconductor is deposited on this, or the above-mentioned substrate and the above-mentioned A substrate made of a material that has good compatibility with the ceramic superconductor described above and on which the ceramic film deposited on this substrate can become a superconductor, and A fine pattern of a thin film made of a material such that the deposited ceramic film cannot become a superconductor is formed, and the above-mentioned ceramic superconductor is deposited thereon, followed by heat treatment.

When carrying out the present invention described above, a substrate made of the first material that has poor compatibility with a ceramic superconductor such as alumina or silicon is used, and a thin film material made of the second material is zirconia, silicon, etc. It is preferable to use a thin film material of a material having good compatibility with the ceramic superconductor, such as zirconia containing yttrium, platinum, silver, magnesium oxide, strontium titanate, etc., or as a substrate made of the above-mentioned first material, zirconia.

A substrate made of a material that has good compatibility with the ceramic superconductor, such as yttrium-containing zirconia, platinum, silver, magnesium oxide, and strontium titanate, is used, and a thin film material made of the above second material is made of alumina, silicon, etc. It is preferred to use thin film materials of materials that are poorly compatible with ceramic superconductors.

Effect> There is poor matching between the substrate and the ceramic superconductor, and the ceramic film formed thereon cannot become a superconductor.On the substrate, there is good matching with the ceramic superconductor, and the ceramic film formed on this material becomes superconducting. A fine pattern of a thin film material that can become a body is formed, and the above-mentioned ceramic superconductor is deposited on this, or a ceramic film formed on this is formed so that the above-mentioned substrate and the above-mentioned ceramic superconductor match well. On a substrate that can become a superconductor, the ceramic film formed on the substrate has poor matching with the ceramic superconductor, forming a fine pattern of a thin film that cannot become a superconductor, and then the ceramic superconductor is deposited on top of this. Filmed and heat treated,
A desired superconductor fine pattern can be obtained by making a superconductor only on a thin film or a substrate that has good compatibility with the ceramic superconductor and on which a ceramic film formed thereon can serve as a superconductor.

<Example> Hereinafter, an example of the present invention will be described in detail with reference to the drawings.

FIGS. 1(a) to 1(c) each show a process diagram of a method for manufacturing a ceramic superconductor according to an embodiment of the present invention.

First, as shown in Figure 1(a), sapphire (Adz
A ZrO2 thin film containing Y was deposited to a thickness of about 1000 Å on a substrate 1 using high-frequency magnetron sputtering, and a fine pattern 2 of ZrO2 containing Y was formed by ordinary photolithography and dry etching.

Next, as shown in FIG. 1(b), using high frequency magnetron sputtering, Y-
A Ba-Cu oxide target was sputtered with Ar+02 gas to a thickness of about 1 μm (') Y:Ba:Cu=I:2:
An oxide thin film 3 having a composition ratio of 3 was formed. At this point Y
-Ba-Cu oxide did not exhibit superconductivity.

After this, heat treatment was performed at 900°C for 5 hours in 02 atmosphere, and 2°C
/min to 100°C (Figure 1 (C))
.

AI of this heat-treated substrate l! The electrical resistance of the Y-Ba-Cu oxide film (4 and 5, respectively) on the 2o3i and on the two surfaces of the ZrO2 thin film containing Y was measured by the four-probe method after depositing a Ti electrode of approximately 6oooX. As shown in characteristic (a) of Figure 2, the busy Ae203
The Y--Ba--Cu oxide film on the surface had high resistance, and temperature changes in electrical resistance showed semiconductor characteristics and did not become superconducting.

On the other hand, the electrical resistance of the Y-Ba-Cu oxide film on the ZrO2 surface containing Y shows a metallic change as shown in characteristic (■) in Figure 2, and the superconducting transition begins at about 92 and the resistance reaches about 82. became 0. Also, AI! by Auger electron spectroscopy! 203
Analysis of the oxide film on the surface revealed AI in the thickness direction! was found to be widespread. No diffusion of At was observed on the ZrO2 surface containing Y. Also, X-ray diffraction revealed that the Y-Ba-Cu-0 film on the ZrO2 surface containing Y was a single phase with an orthorhombic structure, but AI! Y-Ba-C on 203 plane
It was found that the u-0 film contained an At peak and a phase other than orthorhombic. As described above, by annealing after forming the Y-Ba-Cu-0 film, AI is transferred from the Ae2o3 plane to Y-B
By diffusing into the a-Cu-0 film, Y-Ba-C
It was found that various insulating layers were formed on u-0, resulting in high resistance and no superconducting phase was formed. It was also found that ZrO2 acts as a layer to prevent Al diffusion. Furthermore, the characteristics of Y-Ba-Cu oxide superconductor on ZrO2 containing Y are 2
It was stable even when left indoors for more than a month.

On the contrary, AI is applied to a ZrO2 substrate containing Y! 203 thin film pattern is formed, Y-Ba-Cu oxide is deposited on this,
In the case of heat treatment, almost the same results as above were obtained. In addition to ZrO2 containing Y, fgO,5 to ZrO2°
Even when rTi03 or the like was used, the effect of preventing At diffusion was almost the same, but the superconducting properties were the best when using zro2 containing Y.

Furthermore, when Si is used for the substrate l or a thin film formed on the substrate l, the thermal expansion coefficient of Si is significantly different from that of the Y-Ba-Cu oxide superconductor.
U oxide did not become a superconductor even after heat treatment. Furthermore, Y--Ba--Cu oxides on Pt and Ag exhibited superconductivity.

In addition, as a ceramic film, Re-Ba-Cu oxide (Re
-Y) other than Re = Yb, Tm, Er, Ho, Dy,
Gd.

Similar implementation was possible when Eu, Sm, and Nd were used.

<Effects of the Invention> As described above, by using the present invention, ceramic superconductors can be processed without directly wet or dry etching.
It becomes possible to obtain a fine pattern of a ceramic superconductor without impairing the characteristics of the superconductor.

Furthermore, by using such a method for producing a ceramic superconductor, it becomes easy to form various superconducting elements such as magnetic detection elements and Josephson elements using ceramic superconductors.

[Brief explanation of the drawing]

FIGS. 1(a) to (c) are process diagrams showing a method for manufacturing a ceramic superconductor according to an embodiment of the present invention, and FIG. 2 is a diagram showing the electrical properties of the ceramic superconductor and non-superconducting portions manufactured using the present invention. FIG. 3 is a characteristic diagram showing temperature changes in resistance. 1...Substrate, 2-ZrO2 thin film, 3-...-Y-Ba
-Cu oxide thin 1 copy, 4-ZrO2 surface, 5.-At20
3 sides.

Claims (1)

[Claims] 1. The method comprises the steps of forming a fine pattern of a thin film material made of a second material on a substrate made of a first material, and thereafter depositing a ceramic superconductor as a film; As either the first or second material, a material is used that has poor compatibility with the ceramic superconductor and a ceramic film deposited on the material cannot become a superconductor; The other material of the first or second material is a material that has good compatibility with the ceramic superconductor and that allows the ceramic film deposited on the material to become a superconductor. A method for producing a ceramic superconductor.