JP2742097B2 - Method for producing oxide superconducting thin film - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for producing a high-temperature superconductor crystal thin film. In particular, the present invention relates to a method of mass-producing high-quality superconducting thin films at low cost in the production of oxide superconducting thin films by using sputtering, plasma-assisted vapor deposition, laser-assisted vapor deposition, or a combination thereof.

[Prior Art and Problems to be Solved by the Invention] The conventional techniques for manufacturing an oxide superconducting thin film can be roughly classified into two.
Was kind. One is to use an oxide superconducting material target and deposit an oxide superconducting thin film (as dep
In this method, a superconducting thin film having superconducting properties is formed by osit), or heat treatment is performed after deposition. Another method is to use a metal or an alloy thereof as a target, stack these thin films and then perform a heat treatment to cause an oxidation reaction or the like to form a superconducting thin film.

All of these have advantages and disadvantages, and it has been difficult to mass-produce high-quality superconducting multilayer structures. That is, in the example of the first method, using a MgO single crystal substrate, as a target material, by using a _{YBa 3.5 Cu 3.5 O X (X} = 5.0~6.0), load power, in the case of 100～150W, adult The film speed was about 30-50 ° / min, which was extremely low. Further, when the load power is increased to increase the growth rate of the thin film, re-sputtering occurs from the substrate side, and the composition component fluctuates, so that it has been difficult to obtain a high-quality superconducting thin film with high manufacturing efficiency.

In the second method, for example, when a yttrium metal or BaCu alloy is used as a target material on a MgO single crystal substrate, a thin film of these alloys is formed at a load power of 30 to 40 W. It is about 200-1500〜 / min, which is extremely fast. However, this alloy thin film does not exhibit superconductivity and requires heat treatment after film formation. When the thickness of the alloy thin film exceeds 1000 mm in this heat treatment step, the crystallinity of the superconductor rapidly deteriorates. The reason is that when the alloy is thin, when annealing, the alloy is MgO
Influenced by the crystal lattice of the single crystal substrate, the crystal should have a lattice constant close to that of the MgO single crystal, and a good quality superconducting thin film should be produced. In this case, the influence from the crystal lattice of the substrate is reduced near the surface, and uncontrolled crystals are easily formed, resulting in a low-quality superconducting thin film. It was difficult to create with.

In order to solve the technical problems as described above, the present invention creates a multilayer film structure by alternately combining a desired oxide superconducting thin film layer and a metal or alloy of an element constituting the thin film layer. Then, heat treatment is performed to produce a desired oxide superconducting thin film as a whole.

The feature of the manufacturing method of the present invention is that when a thin film layer of a metal or an alloy thereof or a combination thereof is oxidized by heat treatment in an appropriate thickness range to form an oxide crystal,
Influenced by the lattice constant of the surrounding oxide superconducting thin film crystal, it was found to be integrated with the superconducting thin film crystal to produce a good oxide superconducting thin film, and developed as a manufacturing technology for oxide superconducting thin film. It is a thing.

[Means for Solving the Problems] That is, the present invention provides a method for forming a desired oxide superconducting thin film layer having a predetermined thickness on a substrate surface and a range affected by the lattice constant of the oxide superconducting crystal. A metal as a precursor of the oxide superconducting thin film having a thickness of or a thin film layer of an alloy having a desired ratio of these metals is alternately laminated in multiple layers to form a multilayer structure, and then obtained. A method for producing an oxide superconducting thin film, characterized in that an oxide superconducting film having a desired thickness as a whole is obtained by heat-treating the alternate multilayer structure.

Then, the thin film layer in contact with the substrate surface can be a thin film of an oxide superconducting thin film layer, a metal serving as a precursor of the oxide superconducting thin film layer, or an alloy of a desired ratio of these metals.

Also, a desired number of insulating layers can be inserted at desired locations between the multilayer structures. At this time, the elements constituting the upper and lower superconducting layers sandwiching each of the insulating layers may be partially or entirely different.

Further, the desired superconducting crystals, LnBa _I Cu _J O _K based superconducting material (wherein, Ln = Y, La, Nd , Sm, Eu, Gd, Dy, Ho, Er,
Any of Tm, Yb, Lu or a combination thereof;
Is in the range of 1.5-3.0, J is in the range of 2.5-4.0,
K ranges from 5.0 to 7.0) or A _M Ca _N-1 B ₂ Cu _N O
_{2 (N + 2) + M} superconducting material (where A is Bi, Tl, [D
_1.9-X Pb _x Sb _Y : where D is any of Bi and Tl or a combination thereof, X is in the range of 0.1 to 1.1, and Y is 2.0 or less] or any combination thereof. , B is
Ba or Sr or any combination thereof, M is 0.8 to
N is in the range of 2.8 and N is in the range of 0.8 to 5.8) or a combination thereof.

Further, the insulating layer is made of Al ₂ O ₃ , SiO ₂ , (AE) O (however, AE is any of Mg, Ca, Sr, and Ba), Ln ₂ O ₃
(Ln is Y, La, Nd, Sm, Eu, Gd, Dy, Ho, Er, Tm, Y
Any of oxide ceramics of any of b and Lu) or (AE) F ₂ (where AE is any of Mg, Ca, Sr and Ba) or a combination thereof is suitable.

Further, each of the thin film layers can be formed by using any one of a sputtering process, a plasma assisted vapor deposition process, and a laser vapor deposition process, or a combination thereof.

The thickness of each oxide superconducting film is in the range of 40 to 500 °, and the thickness of the metal or alloy of the element constituting each oxide superconducting thin film formed first is 500 mm. ~Five
Preferably it is in the range of 000 °.

Further, the thickness of the insulating layer is preferably in the range of 40 to 500 °.

 Hereinafter, the present invention will be described in detail.

In order to solve the above technical problems, the present invention provides a first desired oxide superconducting thin film layer formed on a substrate surface, and an elemental metal constituting the first desired oxide superconducting thin film thereon. Or a thin film layer of an alloy thereof, and further, a second desired oxide superconducting thin film layer is formed thereon, and an elemental metal constituting the second desired oxide superconducting thin film thereon, or Forming a thin film layer of the alloy, on which a third desired oxide superconducting thin film layer is formed, according to a desired multilayer structure,
(Oxide superconducting thin film layer)-(Metal and alloy thin film layer)-
(Oxide superconducting thin film layer) by forming a repeating structure of the structure, and by heat treatment of the resulting multilayer structure, the metal and alloy thin film layers of the crystal structure of the upper and lower oxide superconducting thin film Affected, oxidized and crystallized,
Provided is a method for manufacturing a multilayer oxide superconducting thin film, which comprises obtaining an oxide superconducting thin film as a whole.

In the above method, the first, second, third,... Oxide superconducting films may be the same or different. Here, the desired oxide superconductor film, LnBa _I Cu _J O _K based superconducting material (wherein, Ln = Y, La, N
d, Sm, Eu, Gd, Dy, Ho, Er, Tm, Yb, Lu or any combination thereof, I is in the range of 1.5 to 3.0,
J is in the range of 2.5 to 4.0, K is in the range of 5.0 to 7.0) or A _M Ca _N-1 B ₂ Cu _N O _{2 (N + 2) + M} superconducting material (where A is Bi, T
l, (D _{1.9 -X} Pb _x Sb _Y ) (where D is any of Bi and Tl or a combination thereof, X is in the range of 0.1 to 1.1, and Y is 2.0 or less) B is Ba or Sr or a combination thereof, M is in the range of 0.8 to 2.8, and N is in the range of 0.8 to 5.8). be able to.

The thickness of the desired oxide superconducting thin film layer formed here is:
The thickness of the metal and alloy thin film layer is 500-50
A value of 00 ° is preferred. For that purpose, it is preferable to form each thin film layer by using a sputtering process, a plasma-assisted vapor deposition process, or a laser vapor deposition process.

Then, a first desired oxide superconducting thin film layer is formed on the substrate surface, and a metal or an alloy thin film layer of an element constituting the first desired oxide superconducting thin film is formed thereon,
Further, by forming the first desired oxide superconducting thin film layer thereon, a sandwich structure made of the first desired oxide superconducting material is obtained, and further, the insulator thin film layer is formed thereon. Further, a second sandwich structure made of the second desired oxide superconducting material can be formed thereon. Further, an oxide superconducting thin film layer made of third and fourth oxide superconducting materials can be laminated thereon with an insulating layer interposed therebetween, and a multilayer oxide superconducting thin film can be manufactured according to a desired multilayer structure. can do.

That is, a sandwich structure of (oxide superconducting thin film layer)-(metal and alloy thin film layer)-(oxide superconducting thin film layer)-(insulating layer)-(oxide superconducting thin film layer)-. By forming a repetitive structure and heat-treating the obtained multilayer structure, the metal and alloy thin film layers are oxidized and crystallized under the influence of the upper and lower oxide thin film layers, thereby insulating the entire structure. A superconducting thin film having a multilayer structure sandwiching layers can be manufactured.

The first and second superconducting thin films may be the same material or different materials.

Here, the superconducting films, LnBa _I Cu _J O _K based superconducting material (wherein, Ln = Y, La, Nd , Sm, Eu, Gd, Dy, Ho, Er, Tm, Y
b or Lu or any combination thereof, and I is 1.5
~ 3.0, J is in the range of 2.5 ~ 4.0, K
Is in the range of 5.0 to 7.0) or A _M Ca _N-1 B ₂ Cu _N O _{2 (N + 2) + M} superconducting material (where A is Bi, T
l, (D _1.9−X Pb _x Sb _Y ) (where D is any of Bi and Tl or a combination thereof, X is in the range of 0.1 to 1.0, and Y is 2.0 or less) B is Ba or Sr or a combination thereof, M is in the range of 0.8 to 2.8, and N is in the range of 0.8 to 5.8. Is a combination of The insulating layer is made of Al ₂ O ₃ , SiO ₂ , (AE) O
(However, AE is any of Mg, Ca, Sr, and Ba), Ln
₂ O ₃ (Ln is Y, La, Nd, Sm, Eu, Gd, Dy, Ho, Er, T
m, Yb, or Lu) or (AE) F ₂ (where AE is Mg, Ca, Sr, Ba
Or a combination thereof). Preferably, the thickness of the oxide superconducting layer is 40 to 500 、, the thickness of the metal and alloy layers is 500 to 5000 、, and the thickness of the insulating layer is 40 to 500 Å. .

In the present invention, the thickness of the first desired oxide superconducting thin film layer is 40 to 500 °, and the thickness of the metal or alloy thin film layer is 500 to 5000 °. That is, the metal or alloy thin film layer formed first is made thicker than the superconducting oxide to keep the production efficiency high. If the thickness of the metal or alloy thin film is less than 500 mm, the overall production efficiency is limited by the formation of an oxide layer having a low growth rate, which is inconvenient. The effect of the layer is difficult to reach the entire alloy film, which is inconvenient.

In contrast, the initially formed oxide superconducting layer can be relatively thin, in the range of 40-500 °. If it is less than 40 mm, it becomes difficult to obtain a high quality film,
Exceeding Å will limit the overall production efficiency. Therefore, a thin film layer having a thickness in the above range is formed. The thickness of the insulating layer is preferably 40 to 500 °. If the thickness is less than 40 mm, the effect as an insulating layer and the function as a barrier layer for a chemical interdiffusion reaction are insufficient, and if it exceeds 500 mm, the insulating layer becomes completely inconvenient.
Range.

In addition, in order to form such an oxide superconducting layer and an alloy layer, it is preferable to form each thin film layer by using a sputtering process, a plasma-assisted vapor deposition process, or a laser vapor deposition process.

Therefore, in the method for producing an oxide superconducting thin film according to the present invention, an oxide thin film made of a superconducting material is basically laminated, and a metal or an alloy of an element constituting the superconducting material is placed between the laminated superconducting thin films. A multilayer thin film is prepared by inserting a thin film according to (1), and a heat treatment is performed on the multilayer thin film to produce an oxide superconducting thin film.

Here, the substrate is made of a general material used for forming an oxide superconductor thin film, for example, single crystal MgO, single crystal SrTiO.
_{A three} or polycrystalline substrate such as a partially stabilized zirconia plate can be used, but is not particularly limited.

Further, as the target material, a material having a desired composition can be used.

A method and an apparatus for manufacturing a multilayer high-temperature superconductor thin film according to the present invention are shown in the schematic diagrams of FIGS.

The obtained thin film was observed by X-ray diffraction analysis, and the results are shown in FIGS. 4, 5, 6, and 7.

Further, the method for producing an oxide superconducting thin film of the present invention can be further used for forming a superconducting crystal thin film for products such as Josephson junctions, infrared detectors, and optical switches.

Next, the method for producing an oxide superconducting multilayer thin film of the present invention will be specifically described with reference to Examples, but the present invention is not limited thereto.

Example 1 A method and an apparatus for producing a multilayer thin film shown in FIG. 1 will be described with reference to the drawings schematically showing the method.

As a substrate, a metal film and an oxide superconducting material film are formed on the surface of the substrate by sputtering using an MgO single crystal which has a strong influence on the superconducting crystal growth, and the laminated superconducting thin film is subjected to a heat treatment.

Here, an example in which a superconducting thin film is formed by sputtering is shown. Here, the substrate cartridge 1 and the substrate (Mg
O) 2, gate 3, heater 4, substrate preheating chamber 5, YCu sputter chamber 5, BaCu sputter chamber 6, BaCu sputter chamber 7, YBa ₂ Cu ₃ O ₆ sputter chamber 8, annealing chamber 9, conveyor line 10, gas exhaust System 11, annealing gas inlet tube 12, product outlet 13, sputter gun 14, YCu metal film (160
0Å) 15, BaCu metal film (3200Å) 16, YBa ₂ Cu ₃ O ₆ film (100
I) 17, Yba ₂ Cu ₃ O ₆ film (4900 mm) 18, sputter gas introduction pipe (Ar 100%) 19, and sputter gas introduction pipe (Ar + O ₂ 10)
%) There are 20.

The substrate 2 is supplied by the substrate cartridge 1. The supplied substrate 2 is supplied to a conveyor line 10 shown in FIG.
And enters a substrate preheating chamber 5 having a heater 4 via a gate 3. In the substrate preheating chamber 5, the vacuum is maintained while the gate 3 is closed by the gas exhaust system 11, and the substrate 2
Is heated by the heater 4 to improve the cleanliness of the surface. Also, by keeping the temperature of the substrate 2 entering the next YCu sputtering chamber 6 constant, the subsequent sputtering rate and crystallization rate are stabilized. Constant temperature 380
The substrate 2 preheated to ° C. enters the YCu sputtering chamber 6 via the gate 3. Here, the substrate 2 is formed by sputtering a YCu metal film on the surface. Here, the sputtering gas uses Ar gas 100%, enters through the introduction pipe 19, and is exhausted from the exhaust system 11.

In this example, the thickness of the metal YCu film was set to 1600 mm in order to produce a superconducting thin film of 4900 mm, with emphasis on productivity even if the film quality deteriorated. The change in the characteristics of the superconducting layer with respect to the thickness of the metal layer 15 will be described later.

Further, the substrate 2 moves to the next BaCu sputtering chamber 7,
BaCu metal thin film was formed by sputtering to a thickness of 3200 mm.
The proportions of these film thicknesses are determined so as to have the same composition ratio as that of the superconducting thin film when heat treatment is finally performed.

Finally, to improve the properties of this thin film, YBa ₂ Cu ₃ O ₆
Is formed by sputtering. Since this film thickness does not affect the entire crystal, it can be made sufficiently thin within the range of productivity.

The thickness of the YBa ₂ Cu ₃ O ₆ film 17 was 100 °. This is because even if the thickness is further reduced, the productivity does not increase only by increasing the waiting time of the apparatus (see the time chart in FIG. 8).

Then, the substrate 2 entered the YBa ₂ Cu ₃ O ₆ sputtering chamber 8, and was heated to 650 ° C. by the heater 4 to form a 100 ° YBa ₂ Cu ₃ O ₆ film 17 on the surface. Finally, the substrate 2 enters the annealing chamber 9 for performing the heat treatment. The annealing chamber 9 is divided into two chambers, and each chamber can produce a set of tens of substrates at a time. The heat treatment can be operated continuously by annealing each chamber alternately. During the annealing, an annealing gas having a gas composition according to the heat treatment schedule is introduced from the annealing gas introduction pipe 12. The introduced gas is discharged from the exhaust system 11.

This laminated metal-inserted superconducting thin film is heated at 850 ° C in air for 30 minutes.
Annealing was performed for a minute to obtain a YBa ₂ Cu ₃ O ₆ thin film.

In the substrate 2 which has been subjected to the heat treatment in the final step, the laminated metal thin film is heat-treated and oxidized, and a good crystalline YBa ₂ Cu ₃ O ₆ film (490 thick) is formed.
0Å) It becomes 18.

As described above, the superconducting thin film (●) obtained by laminating the superconducting material layers (17 in the above) sandwiching the metal layers (15 and 16 in the above) and heat-treating the superconducting thin film (●) as in the prior art The crystallinity and orientation of the obtained superconducting thin film (○) were simply compared by X-ray diffraction observation. That is, the thickness of the designed superconducting thin film is plotted on the horizontal axis, and YBa ₂
Cu ₃ O ₆ thin film X-ray diffraction peaks and (005), (005) + (1
The vertical axis represents the diffraction line intensity ratio of (03) + (110) and is shown in the graph of FIG.

The X-ray diffraction peak of YBa ₂ Cu ₃ O ₆ was measured after annealing for 30 minutes in air at 850 ° C. with or without a metal film having a thickness T between YBa ₂ Cu ₃ O ₆ layers. Then, comparison was made with the above intensity ratio.

The higher the value of the diffraction line intensity ratio, the higher the (00l) orientation.

In the conventional method, in order to secure productivity, a film is formed by sputtering using only a metal target material, and heat treatment is performed. As is apparent from FIG. 4, the orientation of the superconducting film changes depending on the distance between the metal layer and the superconducting material layer sandwiching the metal layer. That is, in the conventional method, when the metal film thickness exceeds 1000 °, the orientation sharply decreases. In comparison, the superconducting thin film prepared according to the present invention has good orientation,
Even when the thickness exceeds 2000 mm, good orientation was obtained.

In forming a thin film layer by the sputtering process, the conventional technology and the sputtering process conditions, production efficiency, and the like were compared and shown in Table 1.

In Table 1, in the conventional method A, as in the present invention, the productivity is improved by using three sets of sputter guns, and compared with other methods. On the other hand, in the conventional method B, 4 spatter guns are used.
This is compared with the case where productivity is improved using a set. On the other hand, in the present invention, the production measurement is about 15 times faster than the conventional method A, 270 times faster than the conventional method B, and 270 times faster than the conventional method C. The production speed is almost the same.

In addition, the power required for production is about
One-fifteenth, and one-twentieth of the conventional method B, which is slightly higher than the conventional method C.

The cause of such a difference is that, as shown in Table 2, the metal has a deposition rate that is 20 to several hundred times faster than its oxide. This is because productivity becomes extremely higher than when the oxide target material is used.

In addition, when a thin film is formed using a plurality of target materials, in order to adjust the chemical composition of the final film to a desired value, a compound having the slowest film forming speed among several target materials is used. You. For example, in the conventional method, since the sputtering rate of Y ₂ O ₃ is low, it is difficult to form a film. In the case of metal Y, the productivity is 250 times higher. In addition, as shown in Table 1, the film formation rate does not change so much for metal as an alloy or metal alone. For this reason, even if a YCu alloy having the slowest film formation measurement is used, it is about 65% of the Cu metal having the largest film formation rate, and the productivity does not decrease much. However, in the case of an oxide target material, not only the overall film forming rate is low, but also the difference between the target materials is large.

Therefore, in the method of manufacturing an oxide superconducting thin film according to the present invention, a thin film using an oxide target material is formed into a sandwich-like structure while using a metal target and a high film forming rate, and the crystallinity of the film is improved. Using only the oxide target material, it is possible to have almost the same performance as the formed thin film.

[Example 2] A description will be given of the production of a laminated superconducting thin film in which partially stabilized zirconia is used as the substrate 2 and the superconducting thin film has a thickness of 9800 °.

However, since the substrate is made of polycrystalline partially stabilized zirconia, a YBa ₂ Cu ₃ O ₆ film is first formed on the surface of the substrate by sputtering, and then a metal film is formed by sputtering.

A description will be given with reference to FIG. 2 which schematically shows a manufacturing apparatus. Here, a substrate cartridge 1, a substrate (partially stabilized zirconia) 2, a gate 3, a heater 4, a substrate preheating chamber 5, a YBa ₂ Cu ₃ O ₆ sputtering chamber 6, a YCu sputtering chamber 7, a BaCu sputtering chamber 8, and an annealing chamber 9 , Conveyor line 10, gas exhaust system 11, annealing gas introduction pipe 1
2, Product outlet 13, Sputter gun 14, YBa ₂ Cu ₃ O ₆ thin film (100
Å) 15, BaCu metal film (3200Å) 16, BaCu film (3200Å) 1
7, YBa ₂ Cu ₃ O ₆ film (9800Å) 18, sputter gas introduction pipe (Ar
100%) 19 and a sputtering gas introduction pipe (Ar + O ₂ 10%) is 20.

The substrate 2 is preheated from the substrate cartridge 1 through the gate 3 to 650 ° C. in the preheating chamber 5 and enters the YBa ₂ Cu ₃ O ₆ sputtering chamber 6. Next, in the YCu metal sputtering chamber 7, the substrate temperature is lowered to 360 ° C. by controlling the heater 4, and the YCu metal layer is sputtered to a thickness of 1200 °. Further, YBa ₂ Cu ₃ O ₆ is sputtered on these surfaces to a thickness of 100 °. On this, metal films YCu and BaCu are again laminated in a similar manner to a thickness of 1600 mm and 3200 mm, respectively. Finally, when heat-treated in the annealing chamber 9, a high-quality superconducting thin film having a thickness of 9800 mm is obtained.

The superconducting film has a relatively strong orientation since it is sandwiched by a superconducting thin film on the upper and lower sides, and is of good quality.
Since the upper metal thin film is in contact with the crystal YBa ₂ Cu ₃ O ₆ on only one side, the crystal quality obtained by annealing is slightly reduced. To prevent this, use a similar method to apply YBa ₂
If Cu ₃ O ₆ is further sputtered, a better superconducting thin film can be obtained.

FIG. 5 shows an X-ray diffraction pattern of the YBa ₂ Cu ₃ O ₆ thin film prepared according to the present embodiment in the upper part and an X-ray diffraction pattern of the conventional superconducting thin film in the lower part. Total thickness 10,000Å, 8
It was obtained by annealing at 50 ° C for 30 minutes in air.
FIG. 5 clearly shows that each of the superconducting thin films (00
l) The peak is sharper and more crystalline than the conventional method,
It shows that the orientation is excellent.

FIG. 6 shows that a thin film of 10000 mm thick contains 50 mm of YBa ₂ Cu ₃ O ₆
4 is a graph showing the relationship between the number of layers (the number of steps) of the YBa ₂ Cu ₃ O ₆ film and the properties of the crystal when a sandwich structure is formed with the film.

That is, by changing the number of superconducting material layers to be inserted in the lamination, the alloy layer and the superconducting layer were formed by sputtering lamination up to 10,000 °, and the laminated structure was annealed in air at 850 ° C. for 30 minutes to obtain The intensity ratio between the X-ray diffraction peak (005) and (005) + (103) + (110) of the obtained YBa ₂ Cu ₃ O ₆ thin film is shown on the vertical axis. For reference, the thickness between superconducting layers calculated from the number of steps inserted at 10000 ° on the upper axis is indicated by Å.

In order to obtain a good crystalline superconducting thin film having a thickness of 10,000 mm, approximately six layers (n = 6) are sufficient, and the conventional method (n =
The peak more than twice of 2) appears.

[Example 3] A process of manufacturing a superconducting film / insulating film / superconducting film laminated structure with high quality and high efficiency after an annealing process will be described. Here, the substrate cartridge 1 and the substrate (Mg
O) 2, gate 3, heater 4, substrate preheating chamber 5, YCu sputter chamber 6, BaCu sputter chamber 7, YBa ₂ Cu ₃ O ₆ sputter chamber 8, annealing chamber 9, conveyor line 10, gas exhaust system 11, annealing gas Inlet tube 12, product outlet 13, sputter gun 14, YCu thin film (1600 mm) 15, BaCu metal film (320
0Å) 16, YBa ₂ Cu ₃ O ₆ film (100Å) 17, YBa ₂ Cu ₃ O ₆ film (4900
Ii) 18, a sputter gas introduction pipe (Ar 100%) 19, a sputter gas introduction pipe (Ar + O ₂ 10%) 20, an insulating film sputtering chamber 21, and an insulating film (MgO: 200 °) 22.

MgO was used for the substrate in the same manner as in Example 1, and after preheating it, the YCu alloy and the BaCu alloy were laminated at 16003 and 3200Å, respectively, and then YBa ₂ Cu ₃ O ₆ was deposited at a thickness of 100Å.
YBa ₂ Cu ₃ O ₆ is further laminated to a thickness of 100 mm to a thickness of 200 mm, followed by YCu
The alloy and the BaCu alloy were subjected to a sputtering treatment to a thickness of 1200 mm and 3200 mm, respectively. The structure completed so far is as follows.

Substrate / YCu (1600Å) / BaCu (3200Å) / YBa ₂ Cu ₃ O ₆ (100
Å) / MgO (200Å) / YBa ₂ Cu ₃ O ₆ (100Å) / YCu (1600Å)
/ BaCu (3600Å) When this is heat-treated, the substrate / YBa ₂ Cu ₃ O ₆ (4900Å) / MgO
(200Å) / YBa ₂ Cu ₃ O ₆ (4900Å) structure is obtained.

[Example 4] Fig. 7 A, B, for _{Tl 2 Ba L Ca M Cu N} O 2N + 2 based superconducting film, in order to compare with the thin-film forming method and the conventional method according to the present invention, X-ray diffraction Shows the crystallinity and orientation measured by the line. That is, the X-ray diffraction pattern of the Tl ₂ Ba _L Ca _M Cu _N O _{2 N + 2} superconducting microcrystalline thin film according to the present invention is shown in FIG. 7A, and the X-ray diffraction pattern of the conventional superconducting thin film is shown in FIG. 7 shown in FIG. In addition, the result of measuring the low-temperature resistivity of each superconducting thin film,
This is shown in the graph of FIG. 7C. The case according to the present invention is indicated by curve A, and the case according to the conventional method is indicated by curve B. That is, it was measured on a superconducting thin film having a total film thickness of 1 μm and obtained by annealing at 950 ° C. in air.

[Effects of the Invention] The following remarkable technical effects have been obtained by the method for producing an oxide superconductor multilayered structure thin film of the present invention.

First, it is possible to provide a method for manufacturing an oxide superconducting thin film that solves the disadvantage that the film formation rate in the conventional method for manufacturing an oxide superconducting thin film is low and productivity is poor.

Secondly, in the conventional method, the morphology and crystallinity of a thin film after production are extremely poor if only a metal target material is used simply in order to increase the film formation rate. Such disadvantages are eliminated.

Third, by combining a metal target material and an oxide target material, a method for manufacturing a superconducting thin film having high productivity and improved properties of the superconducting thin film is provided.

Fourth, in a method for producing an oxide superconducting thin film, there is provided a superconducting production method capable of increasing production efficiency and further improving the quality of the obtained superconducting thin film.

Fifth, it has become possible to create a multi-layered oxide superconducting thin film in which different types of oxide superconducting thin film layers, which have not been obtained before, are laminated. Sixth, it has a new function. It becomes possible to provide a superconducting material, and the field of electronics application thereof is expanded. For example, a method for producing an oxide superconductor having a structure usable for a Josephson device or the like is provided.

[Brief description of the drawings]

FIG. 1 is a schematic view showing an apparatus and a method for manufacturing an oxide superconducting thin film according to the present invention. FIG. 2 is a schematic view showing another apparatus and method for producing an oxide superconducting thin film according to the present invention. FIG. 3 is a schematic view showing still another apparatus and method for producing an oxide superconducting thin film according to the present invention. FIG. 4 is a graph comparing the crystallinity of the oxide superconducting thin film manufactured according to the present invention and the oxide superconducting thin film manufactured according to the conventional method. The X-ray diffraction intensity ratio is obtained. FIG. 5 shows X-ray diffraction patterns of the oxide superconducting thin film manufactured according to the present invention and the oxide superconducting thin film manufactured according to the conventional method. Indicates a pattern. FIG. 6 is a graph showing the crystallinity of the oxide superconducting thin film manufactured according to the present invention, wherein the horizontal axis represents the number of superconducting layers inserted between 1 μm in total film thickness, and the vertical axis represents X-ray diffraction. The intensity ratio is taken. FIGS. 7A, 7B, and 7C show each of the oxide superconducting thin film manufactured according to the present invention and the oxide superconducting thin film manufactured according to the conventional method in order to compare their crystallinity and orientation. It is a graph which shows an X-ray diffraction pattern and the measurement result of the low temperature resistivity. FIG. 8 shows a time chart for forming each thin film by sputtering according to the present invention.

────────────────────────────────────────────────── (5) Int.Cl. ⁶ Identification symbol FI H01L 39/24 ZAA H01L 39/24 ZAAC (56) Reference JP-A-63-310520 (JP, A) JP-A-1-219018 (JP, A) Japanese Patent Laid-Open No. 1-239021 (JP, A)

Claims (10)

(57) [Claims] A superconducting oxide thin film layer having a predetermined thickness and a desired thickness and a thickness within a range affected by a lattice constant of the oxide superconducting crystal are provided on a substrate surface. A precursor metal or a thin film layer of an alloy having a desired ratio of these metals is alternately laminated in a multilayer to form a multilayer film structure, and then heat-treating the obtained alternate multilayer film structure. Thereby obtaining an oxide superconducting film having a desired thickness as a whole. 2. The method according to claim 1, wherein the thin film layer in contact with the substrate surface is an oxide superconducting thin film layer. 3. The oxidation according to claim 1, wherein the thin film layer in contact with the substrate surface is a thin film of a metal serving as a precursor of the oxide superconducting thin film layer or an alloy of a desired ratio of these metals. Of manufacturing superconducting thin film. 4. The oxide superconducting thin film according to claim 1, wherein a desired number of insulating layers are inserted between said multilayer structure at desired positions. Manufacturing method. 5. An oxide superconducting thin film according to claim 4, wherein the elements constituting the upper and lower superconducting layers sandwiching each of said insulating layers are partially or entirely different. Method. 6. The desired superconducting crystals, LnBa _I Cu _J O _K based superconducting material (wherein, Ln = Y, La, Nd , Sm, Eu, Gd, Dy, Ho, Er, T
m, Yb, Lu or any combination thereof;
Is in the range of 1.5-3.0, J is in the range of 2.5-4.0,
K is in the range of 5.0 to 7.0) or A _M Ca _N-1 B ₂ Cu _N O _{2 (N + 2) + M} superconducting material (where A is Bi, Tl, [D _1.9-X Pb _x Sb _Y : However, D is B
i is any of Tl or a combination thereof, and X is 0.1 to 1.
B is Ba or Sr or a combination thereof, M is in the range of 0.8 to 2.8, and N is 0.8 or less. ~
5.8) or a combination thereof. 7. The insulating layer is made of Al ₂ O ₃ , SiO ₂ , (AE) O
(However, AE is any of Mg, Ca, Sr, and Ba), Ln
₂ O ₃ (Ln is Y, La, Nd, Sm, Eu, Gd, Dy, Ho, Er, T
m, Yb, or Lu) or (AE) F ₂ (where AE is Mg, Ca, Sr, Ba
The method for producing an oxide superconducting thin film according to claim 4 or 5, wherein 8. The oxidation according to claim 1, wherein each of the thin film layers is formed by using any one of a sputtering process, a plasma assisted vapor deposition process, and a laser vapor deposition process or a combination thereof. Of manufacturing superconducting thin film. 9. The thickness of each oxide superconducting thin film formed first is in the range of 40 to 500 °, and the metal or alloy of the element constituting each oxide superconducting thin film formed first. The method for producing an oxide superconducting thin film according to claim 1, wherein the thickness of the film is in the range of 500 to 5000 °. 10. The method according to claim 4, wherein the thickness of the insulating layer is in the range of 40 to 500 °.