JPS63224271A - Superconductor - Google Patents

Abstract

PURPOSE:To make it possible to form a superconduction electronic device applying a ceramic superconductive material, by arranging, on a substrate, YSZ, yttria or zirconia, which are in the form of a thin film and closely in contact with a material generating an oxide superconductive ceramic. CONSTITUTION:A substrate 1 has a surface with a desired shape of YSZ (yttrium stabilized zircon), yttria or zirconia. By a sputtering method or a printing method, a thin film type cermic material 2 is formed on the surface of the substrate 1 so as to be closely in contact with the surface. The ceramic material 2 formed on the surface of the substrate 1 is selectively irradiated by laser light and scanned to transform the irradiated parts only into an oxide superconductive material 4. The residual region 5 in the periphery is turned substantially into an insulating region. In this manner, the ceramic superconductive material 4 is arranged so as to be in contact with YSZ, zirconia or yttria. Thereby, the constitution substantially in the form of a coil, a disc, a film, a line or a belt is enabled.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to thin film ceramic superconducting materials. The present invention relates to a superconductor having a raw material for an oxide superconducting material or a thin film of an oxide superconducting material formed into a thin film on a substrate having a surface of YSZ, yttria, or zirconia. The aim is to use this ceramic superconducting material to create superconducting electronic devices.

"Prior Art" Conventionally, a metal material of Nb-Ge (for example, NbzGe) has been used as a superconducting material. Since this material is a metal, it has high ductility and malleability, making it possible to wind coils for superconducting magnets.

However, superconducting materials using these metal materials have Tc (
The superconducting critical temperature (hereinafter simply referred to as Tc) is small 23
On the other hand, when considering industrial applications, it is more effective if the Tc is 30' K, preferably 776 K or higher.In particular, it is effective if the Tc is at a temperature of 77' K or higher. If a superconducting material is developed, it will be possible to operate in a liquid nitrogen temperature atmosphere, reducing industrial operation and maintenance costs to about 1/10 of the current cost.
It is expected that it will be possible to reduce the amount to less than

``Conventional problems'' For this reason, ceramic materials, especially oxide ceramic materials, are attracting attention as materials with high Tc.However, these ceramic superconducting materials, which are attracting attention, have a high However, it is extremely incompatible with substrate materials that are in close contact with it.

For this reason, a special substrate material had to be chosen.

Furthermore, this ceramic material has poor bendability, ductility, and malleability, and tends to break even when bent slightly. Iwanya 0.1~10
It was thought that it would be completely impossible to form a thin film of .mu.m on a substrate and make part or all of this thin film superconducting. In particular, it was completely impossible to create new electronic devices using this thin film superconductor by creating multilayer wiring using the same photolithography technology used in semiconductor integrated circuits.

"Means to Solve the Problem" The present invention aims to form such a thin film and use this thin film to produce an electronic device.

The present invention uses YSZ (yttrium stabilized zircon), yttrium oxide, or zirconia (zirconium oxide) having a desired shape in advance.
A substrate having a surface of, for example, a cylindrical or plate-shaped substrate was used. Further, a ceramic material, particularly an oxide ceramic material, or a metal material which becomes an oxide ceramic after annealing in an oxidizing atmosphere is formed in a thin film form in close contact with this surface by a sputtering method, a printing method such as a screen printing method, or other methods.

For example, when formed by sputtering, this thin film exhibits an amorphous structure or a polycrystalline structure having microcrystals with a large amount of lattice distortion and lattice defects.

This structure was generally conductive or insulating without semiconducting or superconducting properties.

For this reason, the present invention includes a step of recrystallizing the film in such a state into a band shape having a certain width by heat treatment in an oxidizing atmosphere or by selectively irradiating and scanning the film with laser light. In this process, a laser annealing process is performed only in the area irradiated with laser light to increase the crystallization rate (increase the crystal grain size and create a microcrystalline structure exhibiting superconductivity), and only in this area, the lattice strain , lattice defects can be reduced. At the same time, since it is once melted and recrystallized, impurities other than the crystal structure that should originally have superconductivity are segregated to a certain extent on the irradiated surface, internal impurities are removed, and high purity can be achieved. Then, only this portion can be made of a superconducting material having a constant Tc. The thin film formed by this sputtering method etc. is prepared by adjusting the target and using a ceramic superconducting material such as ('b-X Bax)CuOz, s~z,
s However, x = 0.01~0.1 preferably 0.05~
0.1 intrum ceramic material or (La
d-xBax) zcuOn(BLCO), (La
1-x 5rx) z(SLCO), generally expressed as (Lad-x Ax)zcu04, where A is Ba,
A target material that could be Sr or other material was used.

The laser light source of the present invention is, for example, a YAG laser (wavelength 1.0
6p), an excimer laser (KrF, KrC1, etc.), a carbon dioxide laser, or a nitrogen laser. The former can be repeatedly irradiated with a circular laser beam at a frequency of 5 to 30 KHz, and only the irradiated portion is recrystallized, so that the molecular arrangement with a layered structure is further formed into a layered structure along the surface of the substrate. The feature is that this portion can be made of superconducting material by disposing it. In addition, when using the latter excimer laser, it is possible to pulse and irradiate a surface of, for example, 20 x 30 mm.In the present invention, by squeezing this with an optical system, it is possible to irradiate a circle (10 to 100 μm in diameter).
Alternatively, a belt-shaped laser beam (width: 5 to 100 μm, length: 10 to 40 cm) can be created, and the substrate or the laser beam is continuously moved while irradiating the ceramic film with this laser beam. That is, the crystal grain size in the annealed area to be scanned can be increased to almost that of a single crystal. The particle size is determined by epitaxial growth on the substrate as Sol (Supe).
r-conduction Material On
In5lator).

The present invention is characterized in that the ceramic material formed on the surface of the substrate is selectively irradiated and scanned with laser light so that only that portion is transformed into an oxide superconducting material. Then, the remaining region at the periphery is essentially a vA edge region (an insulating region with theoretically sufficiently high resistance compared to the superconducting region at humidity below Tc).
It becomes possible to do this. Although it is possible to remove this portion, it is also possible to use the material to fill in the recessed portions in order to reduce the level difference in the multilayer wiring.

In the present invention, the substrate materials include alumina, silicon oxide substrate, YSZ (yttoria stabilized zircon), silicon nitride substrate, aluminum nitride, zirconia,
Ittria was used. However, YSZ, ittria, or zirconia, which have the most similar thermal expansion coefficients, can provide a high Tc after laser annealing.

In the present invention, it is not preferable to use a substrate that undergoes an acid-base reaction with oxide superconducting ceramics, such as a silicon oxide substrate or a silicon nitride substrate, and use a substrate that is sufficiently (at least one order of magnitude) more reliable than these as an insulating substrate. Using.

``Action'' For this reason, for oxide superconducting ceramics that are highly susceptible to acid-base reactions and have a large coefficient of thermal expansion,
It was possible to generate materials YSZ, yttria and zirconia that could prevent the reaction and have approximately the same coefficient of thermal expansion. This made it possible for the first time to form oxide superconducting ceramics into a thin film. Regarding the ceramic superconductor of the present invention, a base body in the final shape is provided, and a film-like material (
(does not exhibit superconductivity as it is).

Then, by selectively performing laser annealing on this film, the degree of crystallinity is improved only in the annealed portions. By scanning this laser beam arbitrarily, it is possible to derive an arbitrary line, band, or plane only on the surface area. Only in this region, the resistance decreases at temperatures below Tc, and at Tco (temperature at which the electrical resistance becomes zero), the resistance can become "0" or close to it.

The present invention will be explained below according to examples.

"Example 1" FIG. 1 shows the manufacturing process of the present invention.

In FIG. 1(A), a ceramic material such as yttrium, zirconia or ysz<yttrium stabilized zircon) is used for the substrate (1).

In these cases, it is preferable that the difference in coefficient of thermal expansion be the same (within ±50%) as that of a ceramic thin film. If this difference is too large, stress distortion occurs after annealing, the temperature at which superconductivity is exhibited is low, and superconductivity is not observed.

In this example, this substrate was formed on a plate-shaped substrate by sputtering to a thickness of 0.1 to 20 μm, for example, 2 μm. During this sputtering, the target (YI
-XBax) zcuoz, s~3. . For example, X=0
．． A sufficiently mixed product was used as 075.

It is made into flying particles by sputtering, and a film (2
) was formed. At this time, the substrate temperature is between room temperature and 400°C, for example, 2
Some oxygen was added to the argon in an atmosphere heated to 50°C. After the shape shown in Figure 1 (B) is created in this way, the shape shown in Figure 1 (C) is created.
), excimer laser light (
Wavelength: 0.25 μm) (3) While irradiating, scan continuously as shown by the broken line. Since this is pulsed light, one rectangular spot was made to overlap 80 to 98% of the next rectangular beam so that the pulse scanned in a continuous manner. That is, the scanning speed of the laser beam was 2 cm/min, and the frequency was 100 cm/min.
KHz, beam diameter 50 μm x 10 cm. Then, only the portions irradiated with this laser light are selectively oxidized, and crystals are arranged microscopically. They were able to create a strip-shaped superconducting thin film with a width of 10 cm. In order not to make the rate of recrystallization too steep, during the process shown in FIG. 1(C), the entire substrate is heated by laser annealing or Optical annealing was performed. Then, the temperature of the part irradiated with the laser beam or equivalent strong light was set to 1000° C. or higher, at which the irradiated ceramic material would not sublimate. The occurrence of cranks could be prevented by rapid cooling to room temperature after irradiation with light.

In this example, Tc was 43°K.

Thus, by irradiating this laser light or strong light, it was possible to create a region having Tc substantially in the form of a band or line.

"Example 2" FIG. 2 shows another embodiment of the invention.

In the drawing, the base body (1) has a cylindrical shape. Here, similarly to Example 1, a ceramic material (2) is formed in the form of a film by sputtering.

For this production, use a sputtering device to connect this cylindrical substrate to the arrow (12).
The coating may be applied while rotating as shown in the figure.

Next, while irradiating the substrate on which these films are formed with a YAG laser (3) beam diameter (50 μm), this laser light (1
Gradually move in the direction of 1). At the same time, rotate the cylinder in the direction of arrow (12). Then, a region (4) having one continuous band-like Tc can be formed on this cylindrical substrate. The adjacent portion (5) is left as a region without Tc. In other words, a superconducting magnet coil can be constructed which is essentially the same as forming a thermoelectric wire in the form of a coil.

FIG. 4 shows a multi-layered superconducting wire formed by repeating these steps.

This corresponds to the longitudinal sectional view taken along line AA' in FIG. The structure of the drawing is abbreviated.

A first ceramic material is coated (2-1) on the substrate (1). After this, the laser beam (4-1), (
4-2)...(4-n) is irradiated. This can be accomplished by moving the laser beam to the right while rotating the substrate. Then, this laser light is irradiated while scanning continuously, and only the thermally annealed region is transformed into a superconducting material.

A second ceramic material is then formed over these with a membrane coating (2-2). Further, laser annealing was performed in the same manner to form a region (4''-〇) having a band-shaped Tc.

...(4'-2), (4''-1) are made. At this time, the laser tends to bleed downward because it is relatively difficult to control the depth direction. Therefore, (4'-1), (4'-
The position of 2) is the region (4-1) with Tc below it.
, (4-2) . . . , and are arranged above the Tc-free region (5-1) , (5-2) . This (4-1) goes around the coil once and (4-2)
are electrically linked. These ends (4-n) are connected to the second layer (4'-n) at (10-1).

Furthermore, the other end (4'-1) of this second layer opening is connected to the third layer (4''-1) and (10-2), and the region having the 3Nth Tc is (4° '-1), (4"-2
) ...(4″-〇), and further (10
Connect with the fourth layer in -3). In this way, even in the case of a multilayer structure (here, a 4N structure), one long wire is wound repeatedly, and the structure can be substantially the same as that of multilayer winding of a coil.

In the embodiment shown in FIG. 4, (5-1) and (5-2) are made to have approximately five times the width of (4-1) and (4-2),
(4'-1), (4"-1) (4"-1) is (
5-1) to prevent short-circuiting of the lead wires between the respective layers. By repeating this process, multilayer wiring can have one to several tens of layers. In addition, in this case, they were connected in series as if they were one superconductor. However, they may be connected in parallel depending on the purpose. External extraction electrodes, leads <30) and (30') were provided.

The rest is the same as in Example 1.

"Example 3" FIG. 3 is a drawing showing another embodiment of the present invention.

In the drawing, a substrate (1) of YSZ, yttria, or zirconia has a disk shape, and a laser beam (3) larger than this diameter is applied linearly.

Thereafter, this disk (1) is repeatedly and continuously rotated. Then, optical annealing can be repeated. Then, this ceramic thin film gradually aligns its crystal alignment and can grow into crystals over a large area. Thereafter, it is recrystallized along the upper surface of the substrate to form a layered structure with molecular alignment.

Although this figure shows a single-layer disk configuration, it is possible to have a multi-layer configuration similar to the embodiment shown in FIG.

Tc of the region subjected to laser annealing in this oxidizing atmosphere
obtained 43°K.

``Effect'' By providing a ceramic superconductor in contact with these ysz, zirconia, or yttria, which has been thought to be completely impossible until now, the present invention allows a substantially coil-like, disk-like, or film-like wire or band-like structure to be formed. It became possible to do so.

As a ceramic superconducting material that easily warps when bent, it was possible to make it into a thin film as a solid material for conductors or superconducting elements.

In the present invention, after forming a superconducting thin film on a substrate of YSZ, yttria, or zirconia, a predetermined buttering process is performed using a known photolithography technique to form a superconducting element or superconducting wiring, which facilitates its industrial application. This is important when you think about it.

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

[Brief explanation of the drawing]

FIG. 1 shows the manufacturing process of the superconductor of the present invention. 2, 3 and 4 show embodiments of the superconductor of the present invention. 1... Substrate 2... Ceramic material 3... Laser light 4... Band-shaped region exhibiting superconductivity 5... Region not exhibiting superconductivity

Claims (1)

[Claims] 1. When forming a material capable of producing an oxide superconducting ceramic in the form of a thin film on a substrate, YS
A superconductor characterized by being provided with Z, yttria or zirconia. 2. In claim 1, the material that produces a superconducting state in the form of a thin film is made of a thin film of an oxide ceramic material, and has a coefficient of thermal expansion comparable to that of this thin film (within ±50%). A superconductor.