JPH04114996A - Production of thin superconducting element film - Google Patents

Abstract

PURPOSE:To effectively obtain a thin superconducting element film having excellent continuity and uniformity by filling and burning a solution, melt or powder of oxide superconducting raw material in a hollow part formed on a substrate. CONSTITUTION:Hollow forming members 3A and 3B made of a resin, previously formed and having final shape are bonded through an adhesive 4 on a substrate to form a hollow part 2 having 0.1-1000mum depth. Then a solution containing an oxide superconductor raw material is packed in the hollow part 2 or melt containing the oxide superconducting raw material is packed therein or powder of oxide superconducting raw material two times larger than volume of the oxide superconducting raw material is packed therein and heated to 1050-1200 deg.C to melt the material and then burned at 800-970 deg.C for 0.5-2hr and quickly cooled and solidified.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method for manufacturing a thin film superconducting device, and particularly relates to a method for manufacturing a thin film superconducting device, and in particular, a thin film having a thick film of an oxide superconductor formed on a substrate in a desired pattern. The present invention relates to a method for manufacturing superconducting elements with high production efficiency.

[Prior Art] Thin film superconducting elements having a thick film of oxide superconductor formed in a predetermined pattern on a substrate are industrially useful as thin film coils, microinductors, microwave element circuits, etc. be.

Conventionally, CVD, sputtering, coating methods, etc. have been known as methods for forming oxide superconductor thick films on substrates, and the formed thick films can be processed as needed to form various superconducting elements. A method for manufacturing has been proposed.

[Problem to be solved by the invention] Among the conventional methods mentioned above, CVD and sputtering methods are being actively studied because they are easy to obtain high-quality thin films, but they have problems in terms of productivity and manufacturing cost. .

On the other hand, as a coating method, a method has been proposed in which a slurry of raw material powder is used to form a desired shape, but this method has the drawback that sufficient superconducting properties cannot be obtained. Furthermore, coating methods using organic acid salts have the drawback that the concentration of raw materials is extremely low and the coating cannot be applied thickly, resulting in low productivity.

The present invention solves the above conventional problems and makes it possible to easily and efficiently manufacture a thin film superconducting element having a thick film of an oxide superconductor formed on a substrate in a desired pattern. The object of the present invention is to provide a method for manufacturing an element.

[Means for Solving the Problems] The method for manufacturing a thin film superconducting device according to claim (1), in manufacturing a thin film superconducting device having an oxide superconductor film on a substrate, comprises four parts formed on a substrate. The method for manufacturing a thin film superconducting device according to claim (2), characterized in that a solution containing an oxide superconductor raw material is filled in the substrate and then fired at a temperature for forming the oxide superconductor. In manufacturing a thin film superconducting element having a oxide superconductor film, a recess formed on a substrate is filled with a melt containing an oxide superconductor raw material, and then fired at the oxide superconductor forming temperature. The method for manufacturing a thin film superconducting device according to claim (3) is characterized in that when manufacturing a thin film superconducting device having an oxide superconductor film on a substrate, an oxide superconductor is added to a recess formed in the substrate. The method is characterized in that after filling and melting conductor raw material powder, it is fired at the temperature for forming the oxide superconductor.

In addition, as the oxide superconductor film of the superconductor element manufactured by the method of the present invention, for example, the following [T] or [I
Examples include oxide films containing bismuth and copper such as I.

[1] LI Ba2CI4307-6 (Ln = Y,
Rare earth elements such as Nd and Yb) [II Co Bi
2 5r2- X Cal+ x Cu0a+, 5
The present invention will be explained in detail below with reference to the drawings.

1 and 2 are cross-sectional perspective views showing a recess formed in a substrate, FIG. 3 is a cross-sectional perspective view of a recess forming member, and FIG. 4 is a cross-sectional perspective view showing a mask for forming a recess.

In the method of the present invention, first, a recess is formed in the substrate. There is no particular restriction on the method of forming this recess, and for example, the following method (1) or (2) may be employed.

(2) As shown in FIG. 1, a concave portion such as a concave groove 2 is formed in the substrate 1''2. Specifically, the following methods (1) to (2) may be mentioned.

(2) During molding of the substrate (for example, during pressure molding), it is preformed into a shape having a concave portion, and fired if necessary.

■ Form recesses by mechanical processing (cutting). That is, after a concave portion is formed in the substrate molded body by G3 machining, it is fired if necessary. Alternatively, a recess is formed in the substrate 1 after sintering by machining.

(2) A recess is formed by etching a portion using a lithography technique used for semiconductor devices, such as photolithography.

(2) As shown in FIG. 2, recess forming members 3 (3A, 3B) made of resin or the like are legally provided on the substrate IA. Specifically, the following methods (1) to (0) may be mentioned.

(2) As shown in FIG. 3, a resin concave part forming member 3 (3A3B) having a pre-formed final shape is adhered to the substrate with an adhesive 4 or the like.

■ Screen print the resin in a predetermined shape on the board, or
Alternatively, a mask 5 (5A, 5B) as shown in FIG.
is placed on a substrate, coated with resin, and then cured.

■ A pattern is formed on a substrate using normal lithography using a resist. This method is advantageous when forming fine patterns.

Note that the substrate materials used in the present invention include MgO,
SrTiO3, ZrO2, etc., which have been conventionally used as substrates for forming oxide superconductor films such as copper oxide,
In addition, any material that does not react with oxides such as copper oxide during firing can be used. These substrates may be polycrystalline or single crystalline as long as the surface on which the oxide superconductor film is formed is flat. However, it is preferable that the porosity be as low as possible.

In addition, the resin material, adhesive, and resist constituting the concave portion forming member in (2) are those that will not deteriorate in the subsequent step of forming an oxide superconductor film, for example, as claimed in claim (1).
In the method, the oxide superconductor raw material used must not be deteriorated by the solution containing the raw material (hereinafter referred to as "raw material solution"), that is, if the raw material solution is an aqueous solution, it must be insoluble in water; When the raw material solution is an organic solution containing an organic acid salt, it is required to be insoluble in the organic solvent. Specifically, when a toluene solution of naphthenate is used as a raw material solution, a resin, an adhesive, and a resist that are insoluble in toluene are required. Such resins, adhesives,
Specific examples of the resist include resins such as acrylic and epoxy resins, adhesives, and resists. Among these, epoxy resins with a particularly high degree of three-dimensional crosslinking are insoluble in toluene and are extremely suitable for the present invention.

In the method according to claim (1) of the present invention, the recesses formed on the substrate as described above are filled with a raw material solution.

In this case, the raw material solution may be a solution in which an organic acid salt of a constituent element of the oxide superconductor to be formed, such as a naphthenate, is dissolved in an organic solvent such as toluene, or an oxide (carbonate salt) of the constituent element of the oxide superconductor to be formed. ) in an acid such as nitric acid to form an aqueous solution.

For example, when forming the superconductor film of [T] or [n], the raw material solution may include yttrium naphthenate,
A toluene solution containing barium naphthenate, copper naphthenate, bismuth naphthenate, strontium naphthenate, calcium naphthenate, etc. in a predetermined ratio, or a predetermined amount of yttrium oxide (Y2O2), barium carbonate (BaCO3), copper oxide (Cub), etc. A nitric acid solution containing the same proportions can be used.

In the method of claim (2), the melt containing the oxide superconductor raw material is a superconductor whose purpose is to obtain powders of oxides, carbonates, fluorides, etc. of constituent elements of the oxide superconductor to be formed. Examples include those obtained by heating the mixed powder to a temperature higher than the melting point of the mixed powder so as to have a conductive composition.

In addition, this mixed powder may be made by slightly changing the ratio of the desired oxide superconductor composition to make it easier to melt, or to improve the superconducting properties, or by adding other ingredients to the extent that the superconducting properties are not impaired. It is also possible to mix fluxes. Specifically, B
When producing i25r2CaC11206, B i
When the amount of 203 is increased, the melting point decreases. In some cases,
Increasing the amount of CuO also helps improve superconducting properties. In addition to self-fluxes such as Bi2O5 and CuO, addition of PbO, 5b20s, etc. is also effective. YBa2
When producing Cu3O7, a partially molten state can be easily obtained by adding a large amount of CuO or BaO. In addition, rare earth elements (
The mechanical strength can be increased by increasing Y 2 B a Cu O 5 by increasing the amount of Y 2 B a Cu O 5 (Y, etc.).

In the method of claim (3), the oxide superconductor raw material powder (hereinafter referred to as "raw material powder") includes oxides, carbonates, and fluorine of the constituent elements of the oxide superconductor to be formed. An example is a mixture of powders such as chemical compounds in a predetermined ratio. These may be made into a slurry in order to improve the workability of filling the concave portions of the substrate. In this case, the purpose of slurrying is to improve the handleability and compactness of the powder, and therefore, solutionization is not necessary. For example, when producing YBa2Cu3O7, raw material powders of Y203, BaCO5, and CuO are mixed at a ratio of 0.5 mol, 2 mol, and 3 mol, respectively, and mixed with ethyl alcohol, acid, water, etc. to form a slurry. Furthermore, a slurry of YBa2Cu3O7 sintered particles or calcined powder can also be used.

After filling the four parts of the substrate with such raw material powder, 10
Heat to 50-1200°C to melt. Note that since the raw material powder decreases in volume when melted, the raw material powder is filled in an amount approximately twice the volume of the desired oxide superconductor film. After melting, the portion protruding from the recess is removed as necessary.

After filling the recesses of the substrate with the raw material solution in the method of claim (1), or after filling the recesses of the substrate with the raw material melt in the method of claim (2), or after the method of claim (3) After filling the four parts of the substrate with raw material powder and heating and melting it, it is fired at a temperature for forming an oxide superconductor. Firing is typically performed using, for example, Bi25r2CaCu20a
When producing, at 800-880°C for 05-24 hours,
When producing YBa2Cu3O7, 850-970°C
for 0.5 to 24 hours. In addition, claims (2) and (3)
), the melt is preferably rapidly cooled and solidified during firing.

In the present invention, there is no particular restriction on the shape or size of the recess formed in the substrate, and the recess may be a through hole. For example, as shown in FIG.
1 can also be manufactured by filling the above-mentioned raw material solution or raw material melt 12.

Further, as shown in FIG. 6, the substrate 13 has pores 14 and grooves 1.
It is also possible to manufacture by forming a pattern combining 5 and 5 and filling this pattern with a raw material solution or raw material melt 16.

In the embodiment shown in FIG. 6, a superconducting coil is provided which has a superconducting portion in its center that connects with the back surface.

Further, as shown in FIG. 7 (plan view) and FIG. 8 (cross-sectional view taken along the line ■-■ in FIG. 7), the raw material solution or It can also be manufactured by injecting and filling the raw material melt. Further, it is also possible to manufacture the device by combining a plurality of substrates.

The thickness of the oxide superconductor film formed in the present invention is determined by the depth of the recess formed in the substrate, and according to the present invention, the thickness is about 0.1 to 1000 μm, for example,
A superconductor film with a width of 0 μm and a thickness of 30 μm can be formed.

The superconductor element manufactured by the present invention is extremely useful as devices such as thin film coils (for example, for 5QUID), microinductors, and microwave element circuits (delay lines).

[Function] In the method of the present invention, since the recesses formed in the substrate are filled with the raw material solution or raw material melt, it is possible to form a uniformly thick film with extremely good flatness and continuity as confirmed by SEM-EDAX observation. It is possible to efficiently form any type of material according to a desired pattern.

In particular, in the method of claim (1), since a raw material solution that is uniformly dissolved and mixed at the molecular level is used, the productivity is good and the uniformity of the resulting film is extremely excellent. . In this case, as shown in the comparative example below,
With slurry, it is only possible to obtain a film with excellent uniformity.

In addition, in the methods of claims (2) and (3), since a uniformly molten material is used as the raw material melt, the raw material concentration can be increased, and in addition to being excellent in productivity and film uniformity, it is possible to form a thick film. It is said that it is even easier to

[Example] The present invention will be described in more detail by giving Examples and Comparative Examples below.

Example 1 A concave groove with a depth of about 50 μm was formed by machining on an MgO ([001] plane) substrate (thickness 0.5 mm), and in this groove, bismuth naphthenate, strontium naphthenate, and naphthene were formed. Calcium acid, copper naphthenate in toluene 1
A Bi-based naphthenic acid solution obtained by dissolving at a molar ratio of 11.2 was applied. At this time, the coating could be applied selectively almost within the grooves. This was calcined at 430°C for about 20 minutes, and coated and calcined again in the same manner.

This sample was fired at 860°C for 3 hours.

By X-ray diffraction, the obtained superconductor was Bi-based 2212
phase, and as shown in FIG.
It was confirmed that it exhibited good superconducting properties at 6K. Note that the specific resistance was approximately 1 mΩ·Cm.

Comparative Example I A Bi-based naphthenic acid solution was applied in the same manner as in Example 1, except that an MgO substrate without grooves was used, and calcined at 430°C, and again applied and calcined in the same manner. .

When this sample was fired at 860t for 3 hours,
Almost L phase was obtained by line diffraction. However, because the film thickness was not sufficient, optical microscopic observation showed that the film was almost island-like and not uniform. When we measured the electrical properties of this sample, we found that Tc
8nd was 73, and the specific resistance was 105 times higher than that of the example. This is thought to be due to poor connectivity of the membrane.

Comparative Example 2 In Example 1, instead of the Bi-based naphthenic acid solution, B
A slurry made by mixing powders of i2O:+, 5rCOs, CaCO3, and CuO with an average particle size of 1 μm in methanol was used, and this slurry liquid was applied to the grooves, dried at room temperature, and applied again.

When this sample was fired at 860°C for 3 hours, almost L phase was obtained by X-ray diffraction, but Ten
d was 83, but it did not reach completely zero resistance until 4.2K.

Example 2 In Example 1, the molar ratio of the B1 naphthenic acid solution was
Bismuth naphthenate: strontium naphthenate, calcium naphthenate/copper naphthenate = 2+2+1:2, but in the same manner as above to obtain samples having almost identical properties.

Example 3 Novolak-type epoxy acrylate acid aqueous modified product
It was applied onto an O2 ([100] plane) substrate, cured with ultraviolet light (mercury lamp), and annealed at 150° C. for 30 minutes to form recesses. A 60% by weight nitric acid aqueous solution 1
In 0g, Y203, BaCO5, CuO 123(
Molar ratio) Apply a solution in which 6 g of mixed powder is dissolved, and
After heating at 0℃ to release NO8, heating at 950℃ for 24 hours.
Baked for an hour.

nd The Tc of the superconductor film portion of this sample was 90] 5, and it was confirmed by X-ray diffraction that YBa2Cu307-δ was formed.

Example 4 As shown in FIG. 5, a hole with a diameter of 0.5 mm was penetrated on an Mg0 ([100 plane) substrate, and a Bi-based naphthenic acid solution having the same composition as in Example 1 was applied into the hole. It was calcined at 430°C, and this coating and calcining were repeated.

When this sample was fired at 860℃ for 3 hours,! 3 i
A substance identified as 2 S r 3 Ca Cu Q O8+δ filled the pores of the substrate, and the Tcend of the obtained superconductor was 76.

Example 5 A sample having the same characteristics as Example 4 was obtained in the same manner as in Example 4, except that a substrate having the holes and grooves shown in FIG. 6 was used.

Comparative Example 3 The same procedure as in Example 4 was carried out except that the slurry used in Comparative Example 2 was used instead of the Bi-based naphthenic acid solution. However, when measuring electrical resistance, 4.
It did not reach completely zero resistance until 2K.

Example 6 On Mg0 ([001] plane) substrate (thickness 0.5 mm),
A groove with a depth of about 30 μm was formed by machining.

Bi2O3, SrCO3, CaCO3 and CuO in 1.
The mixed powder obtained by mixing at a molar ratio of 2:12 was mixed in ethanol in an amount of 20% by volume, and after thorough stirring and mixing, the precipitate was removed and applied to the concave areas of the substrate.

This sample was held at 890° C. for 1 hour to melt it. In addition,
It was confirmed by SEM observation of the rapidly cooled and slowly cooled samples that the sample was in a molten state at this temperature. This was taken out to room temperature atmosphere and allowed to cool naturally. Next, set the furnace temperature to 810°C, insert the sample into the furnace, and
Baked for an hour.

When this sample was subjected to X-ray diffraction, the amount of B1 superconductor 13 was 2.
Mainly Sr2 CaC11Oa+δ (L phase), Bi2
It was confirmed that a mixture of 5r2Cube+δ was formed. The electrical characteristics of this material are shown in FIG. Further, the resistance value was 3Ω at room temperature, which is 10 times lower than that of Comparative Example 4 described below. This reflects the good connectivity of this embodiment.

Comparative Example 4 In Example 6, the slurry used in Comparative Example 2 was used as the slurry, and this slurry was applied to the grooves of the substrate, dried at room temperature, and applied again.

This was baked at 860°C for 3 hours. At this time, it was confirmed by SEM observation that no melt state clearly existed. Further, almost L phase was obtained by X-ray diffraction, but superconducting Tc8nd was 83 by electrical resistance measurement, but it did not become completely zero resistance until 42K. The electrical characteristics are as shown in FIG.

In addition, in this comparative example, when the firing temperature was set to 810° C., zero resistance was not achieved up to 4.2 K even after firing for 10 hours.

[Effects of the Invention] As detailed above, according to the method for manufacturing a thin film superconducting element of the present invention, an oxide superconductor film can be easily formed according to a desired pattern even if it is a relatively thick film. Moreover, it can be efficiently formed on a substrate, and the obtained superconductor film has extremely excellent film continuity and uniformity. Therefore, according to the present invention, it is possible to manufacture high-performance thin film superconductor elements with high productivity.

[Brief explanation of drawings]

1 and 2 are cross-sectional perspective views showing a recess formed in a substrate, FIG. 3 is a cross-sectional perspective view of a recess forming member, and FIG. 4 is a cross-sectional perspective view showing a mask for forming a recess. FIG. 5 is a perspective view showing another embodiment of the invention, FIG. 6 is a plan view showing another embodiment of the invention, FIG. 7 is a plan view showing a different embodiment of the invention, and FIG. 7 is a sectional view taken along the line ■-■ in FIG. 7. FIG. 9 is a graph showing the results obtained in Example 1, FIG. 10 is a graph showing the results obtained in Example 6,
FIG. 11 is a graph showing the results obtained in Comparative Example 4. DESCRIPTION OF SYMBOLS 1. IA...Substrate, 2... Concave groove, 3... Concave forming member, 4... Adhesive, 5... Mask.

Claims (3)

[Claims] (1) When manufacturing a thin film superconducting device having an oxide superconductor film on a substrate, after filling a solution containing an oxide superconductor raw material into a recess formed on the substrate, the oxide superconductor film is A method for manufacturing a thin film superconducting element, characterized by firing at a forming temperature. (2) When manufacturing a thin film superconducting element having an oxide superconductor film on a substrate, after filling the recesses formed on the substrate with a melt containing the oxide superconductor raw material, the oxide superconductor 1. A method for manufacturing a thin film superconducting element, characterized by firing at a body forming temperature. (3) In manufacturing a thin film superconducting device having an oxide superconductor film on a substrate, the recesses formed on the substrate are filled with powder of the oxide superconductor raw material and then melted. 1. A method for manufacturing a thin film superconducting element, which comprises firing at a superconductor forming temperature.