JPH063766B2 - Superconducting coil manufacturing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION “Field of Use of the Invention” The present invention relates to a thin film ceramic-based superconductivity (also called superconductivity).
The present invention relates to a method for manufacturing a material. The present invention is a superconducting device, preferably a superconducting coil (for energy storage or It is intended to be used for magnets, etc.).

"Background of the Invention" Conventionally, superconducting materials metallic material Nb-Ge (e.g. Nb ₃ Ge) is used. Since this material is a metal, it has high ductility and malleability, and it was possible to perform coil winding for a superconducting magnet.

However, the superconducting material using these metal materials has a small Tc (superconducting critical temperature is hereinafter simply referred to as Tc) and is only 23K or lower. On the other hand, when considering industrial applications, it is more effective that the Tc is 77K, preferably room temperature or higher.

“Conventional Problems” For this reason, ceramic-based materials, particularly oxide ceramic-based materials, are attracting attention as materials with high Tc, rather than metals. However, despite the high Tc, this ceramic superconducting material, which has been attracting attention, has poor bendability, ductility, and malleability, and even if it is bent a little. Iwanya 0.1-30μ
It has been considered completely impossible to form a thin film having a thickness of m on a disk-shaped or disk-shaped substrate and selectively remove a part or all of this thin film. In particular, it has been impossible at all to perform multi-layer wiring using the same photolithography technology as that for semiconductor integrated circuits or to make new electronic devices using this thin film superconductivity.

"Means for Solving the Problem" The present invention does not form an electronic device, preferably a superconducting coil, using such a thin film of an oxide superconducting material and an interlayer separation film of an oxide non-superconducting material containing the same main component sandwiching the thin film. It is what

The present invention preliminarily anneals an oxide superconducting material or a starting material having superconducting properties in a thin film on a formation surface of a base having a desired shape, for example, a cylindrical or disc-shaped base, and a starting material having superconducting properties. Hereinafter referred to as oxide superconducting material or simply superconducting material) as a sputtering method, a printing method such as a screen printing method, a spray method, an electron beam evaporation method,
It is formed by another method.

For example, magnetron sputtering method with substrate temperature 650 ° C, Ar
It is formed in an atmosphere containing 20% oxygen. At this time, the ab plane of the oxide superconducting material (the c plane, that is, the plane perpendicular to the c axis) on the formation surface
Are formed so that they are parallel to each other.

Therefore, when forming a coating film on a substrate, a magnetic field is applied to the surface to be formed in the vertical direction. Then, in the oxide superconducting material of the modified perovskite structure used in the present invention, the plane parallel to the ab plane where the current flows particularly easily is parallel to the formation surface.
This magnetic field is applied to the film formed by the sputtering method in oxygen at 850 ° C,
Add during annealing at 400 ° C for 2 hours during slow cooling at a rate of 4 ° C / min for 8 hours.

The present invention experimentally found that such an oxide superconducting material has a subliming property and can be easily scribed (cut) by an excimer laser or a YAG laser. For this reason, the present invention selectively irradiates the formed superconducting thin film with a laser beam before or after firing, and further scans (scans) as necessary to give a predetermined region,
For example, the oxide superconducting material is removed in a band shape having a certain width. Then, the band of the superconducting thin film having a constant Tc can be formed only in the portion other than the groove formed by the laser irradiation.

For the film formed by the sputtering method, adjust the target,
The oxide superconducting material after formation is, for example, (A _1-x Bx) yCuzOw, where x = 0 to 1 and preferably 0.6 to 0.7, y =
2.0-4.0, preferably 2.5-3.5, z = 1.0-4.0, preferably
1.5 to 3.5, w = 4.0 to 10.0, preferably 6 to 8,
Is one or more elements selected from Group IIIa of the Periodic Table of Elements, particularly yttrium (Y) or lanthanoid, B is one or more elements selected from Group IIa of the Periodic Table of Elements, and B is IIa of the Periodic Table of Elements. It is made to be one or more kinds of elements selected from the group, for example, barium (Ba).

The laser light source of the present invention is, for example, a YAG laser (wavelength 1.06μ
m), an excimer laser (KrF, KrCl, etc.), an argon gas laser or a nitrogen laser was used. The YAG laser can repeatedly irradiate a circular laser beam at a frequency of 5 to 100 KHz, and can sublimate and remove the superconducting material only in the irradiated portion. Although this laser has a long life and can be industrially used at low cost, it is difficult to control in the depth direction because it has an infrared wavelength and a pulse width of 50 ns or more.

Further, when the excimer laser is used, the pulse width is as small as 20 nsec, so that it becomes easier to control the region to be removed in the depth direction. In the present invention, a circular (10 to 100 μm diameter) laser beam can be produced by squeezing an excimer laser with an optical system, and the substrate or the laser light beam is moved while irradiating the oxide superconducting film with this laser beam. At this time, the oxide superconducting thin film at a desired position is removed by sublimation or flying.

Since this oxide superconducting thin film has a relatively small thermal conductivity and is sublimable, it is possible to completely remove the thin film selectively on only the portion irradiated with laser light. The superconducting material is characterized by being able to have a molecular arrangement having a layered structure of copper and oxygen atoms even near the end face thereof.

The present invention thus selectively irradiates the ceramic material formed on the surface of the substrate with laser light and, if necessary, scans to remove the oxide superconducting material only in that portion, and Before and after this, since an oxide non-superconducting material having substantially the same thermal expansion coefficient as this oxide superconducting material is used as an interlayer film for electrical separation on the upper surface, a material having the same element as the oxide superconducting material A material having superconducting properties was laminated. Then, after this, a second oxide superconducting thin film was laminated, and laser scribing was performed again as in the case of the first oxide superconducting material. This was repeated to form a coil wound in multiple layers.

In the present invention, as the base material, alumina, YSZ (yttria stabilized zircon), magnesium oxide
(MgO), silicon nitride, aluminum nitride, zirconia, yttria, strontium titanate (SrTiO ₃ ) and quartz glass were used. Alternatively, a composite substrate may be used by forming an oxide non-superconducting thin film on a substrate such as metal.

[Operation] Conventionally, when a metal superconducting material is used, a wire is first used as the process. The coil was constructed by spreading this on a predetermined substrate.

However, with respect to the coil using the oxide superconductor of the present invention, a substrate having a final shape, for example, a circular or cylindrical shape
(Bobbin) structure is used. After band-shaped superconducting heat treatment is performed on this substrate, an oxide superconducting material that exhibits superconducting properties is formed into a film. Then, by selectively performing laser scribing on this film, a strip-shaped coil is formed by the remaining region of the other portion. Further, an oxide non-superconducting material having the same element as the oxide superconducting material is formed on the upper surface by the same method. Further, the second oxide superconducting thin film is formed while connecting at the connecting portion of the oxide non-superconducting material. Then, second laser scribing is performed on this thin film. Annealing of the oxide superconducting material may be performed after performing all the steps, or may be performed in each step.

The present invention will be described below with reference to examples.

Example 1 FIG. 1 shows an example of the present invention.

In FIG. 1 (A), the substrate (1) used was one in which an oxide non-superconducting thin film (1 ') was formed on a ceramic material (1). Then, it is possible to make a difference in the coefficient of thermal expansion on the upper surface to the same extent (within ± 50%) as that of the oxide superconducting thin film. If this difference is too large, there is stress strain after annealing, the temperature at which superconductivity is exhibited is low, and cracks that occur in the film prevent superconductivity from being observed. In this example, an oxide superconducting thin film (2) having a thickness of 0.1 to 50 μm, for example 20 μm, was formed on a disk-shaped substrate (1) by a sputtering method or a printing method such as a screen printing method.

It was heat-treated in an oxygen atmosphere. It was carried out at 500 to 1000 ° C, for example 900 ° C for 15 hours. Thus, a superconducting ceramic film was formed. After this, the excimer laser (254n
m) (4) was irradiated for laser scribing. In FIG. 1, this laser beam was scanned from the left end toward the center (11), and the disc-shaped substrate was rotated (12). Thus, the open groove (3) was prepared. The laser light had a peak output of 10 ⁶ to 10 ⁸ W / sec. If this is made too strong, the substrate (1) will also be damaged, so care must be taken.

In FIG. 1 (B), after the single-layer wiring of FIG. 1 (A), an oxide non-superconducting thin film (6) is formed on the entire surface thereof, and a second oxide superconducting thin film (7) is further laminated. . It corresponds to the cross section of AA ′ in FIG. 1 (A).

As is clear from the drawing, the first oxide superconducting thin film remains in the form of strips (5-1), (5-2) ... And constitutes a coil. The second oxide superconducting thin film is connected to the laser-scribed coils (7-1), (7-2) ... At the connecting portion (8).

Thus, it becomes possible to wire the strip-shaped wire in a disc shape and to perform the multi-layer winding.

A multi-layer film in which a metal such as silver is provided on or under the first and second strip-shaped superconducting thin films may be used.

Second Embodiment FIG. 2 shows another embodiment of the present invention.

In the drawing, the substrate (1) has a cylindrical shape (bobbin shape). Here, as in Example 1, a film-shaped oxide superconducting material was formed.
Form (2).

This production was performed by using a sputter device.
The deposit may be made while rotating as shown in FIG.

Next, after annealing these films by thermal annealing, while irradiating this film with a YAG laser (3) beam (diameter 50 μm),
Gradually move in the direction of (11). Simultaneously with the arrow on the cylindrical substrate (1)
Rotate in the direction of (12). Then, one continuous strip-shaped scribe line (3) can be formed on this cylindrical substrate. By this groove, each oxide superconducting material is formed into a band shape as (5-1) and (5-2), and each is electrically separated to form a superconducting region. Here, this superconducting region had a coil shape, and a superconducting magnet coil could be substantially constituted.

In this example, after these steps, the whole of them was baked in oxygen to be transformed into an oxide superconducting material represented by the general formula of (A _1-x Bx) yCuzOw. And I was able to make it a superconducting magnet. An energy storage device can be obtained by connecting the start point and the end point of this coil with a superconducting wire.

FIG. 2 (B) corresponds to the cross-sectional view of AA ′ in FIG. 2 (A). FIG. 2 (A) shows only the first layer in order to avoid complication of the drawing. The present invention has a multilayer structure. Fig. 2
In (B), a substrate having an oxide non-superconducting thin film (1 ')
(The oxide superconducting material is formed in a band shape on 19 as shown in FIG. 2A. Further, an oxide non-superconducting thin film containing the same element is formed on the whole by the same sputtering method.
After making a hole in the connecting part (8), a second oxide superconducting thin film is formed on all of them. Further, like the first superconducting thin film, laser scribing is performed to form strips (7-1), (7-2) ...
make. Further, a second oxide superconducting thin film (6 ') was formed, and further a third oxide superconducting material was connected at (8') to form a strip shape. External extraction is done in (10) and (11). By repeating this, it is possible to form not only three layers but also arbitrary layers.

Others are the same as in the first embodiment.

"Effect" The present invention makes it possible to selectively leave the oxide superconducting material, which has been heretofore impossible at all, substantially in the form of a coil on the substrate.

Thus, the ceramic superconducting material that would be easily bent can be isolated to form a conductor, an electrode or a superconducting element, and can be formed into a film or strip.

In the present invention, after forming the superconducting thin film, a known photolithography technique may be used to perform predetermined patterning to obtain a superconducting element or a superconducting wiring. However, the method of the present invention is excellent because it easily deteriorates depending on the liquid used in this step.

The superconducting material of the present invention may be any ceramic material.

[Brief description of drawings]

1 and 2 show examples of superconducting coils using the oxide superconducting material of the present invention. DESCRIPTION OF SYMBOLS 1 ... Substrate 2 ... Oxide superconducting material 3 ... Open groove 4 ... Laser light 5 ... Region which exhibits superconductivity 6,9 / Interlayer separation film 7 ... Second oxide superconductivity material

Claims (3)

[Claims] 1. A step of providing a material having non-superconducting properties on a substrate, a step of providing a band-shaped first oxide superconducting material on the material, and laminating a material having non-superconducting properties on the material. And a step of stacking a second oxide superconducting material on the material so as to be connected to one end of the first oxide superconducting material provided in the shape of a strip and stacking the second oxide superconducting material in a strip shape. A method of manufacturing a coil, wherein a method of removing a part of the oxide superconducting material by laser light is used as a method of providing the oxide superconducting material in a strip shape, and the oxide having a non-superconducting property is used. A method for producing a superconducting coil, which comprises using a material containing an element constituting a superconducting material. 2. The method for producing a superconducting coil according to claim 1, wherein the ratio of the thermal expansion coefficients of the oxide superconducting material and the material having non-superconducting properties is approximately within ± 50%. . 3. The method according to claim 1, wherein a step of providing a first oxide superconducting material, a step of providing a material having non-superconducting properties on the material, and the first oxidation on the material. A step of providing a second oxide superconducting material connected to one end of the superconducting material, and a superconducting coil laminated in multiple layers is formed by performing a plurality of times.