JP2010086796A - Polycrystalline thin film and method of manufacturing the same, and oxide superconductor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polycrystalline thin film which prevents the occurrence of warping of a substrate due to membranous internal stress by reducing an intermediate layer in its thickness while maintaining excellent crystal orientation, and which is superior in productivity; and to provide an oxide superconductive conductor. <P>SOLUTION: The polycrystalline thin film has an intermediate layer 15 laminating a first layer 13 and a second layer 14 through a diffusion preventing layer 9 and a bed layer 12 on a metal substrate 11, and the crystal structures of the first layer 13 and the second layer 14 are respectively a rock salt structure and a fluorite structure, and furthermore, the first layer 13 has a <111> orientation and the second layer 14 has a <100> orientation. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a polycrystalline thin film, a manufacturing method thereof, and an oxide superconducting conductor, and more particularly, a polycrystalline thin film capable of reducing the thickness while maintaining good crystal orientation, a manufacturing method thereof, and the polycrystalline The present invention relates to an oxide superconductor using a thin film.

The RE-123 oxide superconductor discovered recently (REBa ₂ Cu ₃ O _{7-X, where} RE is a rare earth element including Y) is extremely promising in practice because it exhibits superconductivity above liquid nitrogen temperature. There is a strong demand for processing this into a wire and using it as a conductor for power supply.
As a method for processing an oxide superconductor into a wire, a metal having high strength, heat resistance, and easy to be processed into a wire is processed into a long tape shape. In addition, a method for forming an oxide superconductor into a thin film has been studied.
By the way, the oxide superconductor has an electric anisotropy that the crystal itself easily conducts electricity in the a-axis direction and the b-axis direction of the crystal axis, but hardly conducts electricity in the c-axis direction. Therefore, when an oxide superconductor is formed on a substrate, it is necessary to orient the a-axis or b-axis in the direction in which electricity flows and to orient the c-axis in other directions.

However, since the metal substrate itself is amorphous or polycrystalline, and its crystal structure is also significantly different from that of the oxide superconductor, an oxide superconductor film with good crystal orientation as described above is formed on the substrate. It is difficult to form. In addition, since there is a difference in thermal expansion coefficient and lattice constant between the base material and the superconductor, the superconductor is distorted during the cooling to the superconducting critical temperature, or the oxide superconductor film is removed from the substrate. There is also a problem such as peeling.
In order to solve the above problems, first, MgO, YSZ (yttria stable) in which physical characteristic values such as thermal expansion coefficient and lattice constant are intermediate values between the substrate and the superconductor on the metal substrate. An intermediate layer (buffer layer) made of a material such as Zirconia) or SrTiO ₃ is formed, and an oxide superconductor film is formed on the intermediate layer.
Although this intermediate layer has the c-axis oriented perpendicular to the substrate surface, the a-axis (or b-axis) does not align in the same direction in the substrate surface. The layer also has a problem that the a-axis (or b-axis) is not in-plane oriented in substantially the same direction, and the critical current density Jc is not improved.

The ion beam assisted method (IBAD method) is a technique for solving this problem, and is generated from an ion gun when depositing constituent particles knocked out of a target by a sputtering method on a substrate. Argon ions and oxygen ions are deposited while simultaneously irradiating from an oblique direction (for example, 45 degrees). According to this method, high c-axis orientation and a-axis with respect to the film formation surface on the substrate are used. An intermediate layer having in-plane orientation is obtained.
6 and 7 show an example in which a polycrystalline thin film forming an intermediate layer is formed on a base material by the IBAD method. In FIG. 6, 100 is a plate-like base material, and 110 is a base material 100. The polycrystalline thin film formed on the upper surface is shown.

  The polycrystalline thin film 110 is formed by joining and integrating a large number of fine crystal grains 120 having a cubic crystal structure via crystal grain boundaries, and the c axis of the crystal axis of each crystal grain 120 is a base material. The a-axis and the b-axis of the crystal axes of each crystal grain 120 are oriented in the same plane and oriented in the same plane. Further, the c-axis of each crystal grain 120 is oriented perpendicular to the (upper surface) film-forming surface of the substrate 100. The a-axis (or b-axis) of each crystal grain 120 is joined and integrated with an angle formed between them (grain boundary inclination angle K shown in FIG. 7) within 30 degrees.

  The IBAD method is said to be a highly practical production method such as excellent mechanical properties of the wire, easy to obtain stable high properties, etc., but conventionally, an intermediate layer formed by the IBAD method (hereinafter referred to as IBAD method) "IBAD intermediate layer") was said to have no good orientation without a film thickness of about 1000 nm. On the other hand, because the crystal orientation is controlled by ion beam bombardment on a non-oriented metal tape, the IBAD method has a slow deposition rate of about 3 nm / min. .

As a method for solving this problem, a case where an oxide of a fluorite structure series such as YSZ or GdZrO is used (for example, see Patent Document 1 or Patent Document 2), and a case where an oxide of a rock salt structure series such as MgO is used. (See, for example, Patent Document 1), and development research is being actively pursued. Further, there are known MgO films that can be produced by the IBAD method, in which the MgO (111) axis is in the substrate normal direction and in which the MgO (100) axis is in the substrate normal direction.
US 6933065 International Publication No. 2001-040536

However, in the former technique using an oxide of the fluorite structure series, the laminated structure is simple, the film forming conditions are wide, and the lengthening has been advanced, but it is necessary to increase the thickness of the intermediate layer In addition to slowing down the production rate, the internal stress of the film increases and the substrate warps.
The latter method using a rock salt series oxide is expected to drastically solve the above-mentioned problem, but this method is a method of laminating a number of very thin films of several tens of nm or less. Therefore, there is a problem that a lot of know-how is required to maintain the same narrow film forming conditions over a long length.
The present invention has been devised in view of such conventional situations, and by reducing the thickness of the intermediate layer while maintaining good crystal orientation, it is possible to reduce the warping of the substrate due to the internal stress of the film. It is a first object to provide a polycrystalline thin film that is prevented and excellent in productivity.
In addition, the present invention provides an oxide superconducting conductor that is prevented from warping of the substrate due to internal stress of the film, has excellent productivity, good crystal orientation, high critical current density, and good superconducting properties. This is the second purpose.

In order to solve the above problems, the polycrystalline thin film of the present invention has an intermediate layer formed by laminating a first layer and a second layer on a metal substrate via a diffusion prevention layer and a bed layer, The crystal structures of the first layer and the second layer are a rock salt structure and a fluorite structure, respectively, the first layer is <111> oriented, and the second layer is <100> oriented. And
In order to solve the above-mentioned problem, the polycrystalline thin film of the present invention has an intermediate layer formed by laminating a first layer and a second layer on a metal substrate via one diffusion prevention layer, The crystal structures of the first layer and the second layer are a rock salt structure and a fluorite structure, respectively, the first layer is <111> oriented, and the second layer is <100> oriented. To do.
In the polycrystalline thin film of the present invention, the second layer includes an initial portion with <111> orientation and a growth portion with <100> orientation.

In order to solve the above problems, the method for producing a polycrystalline thin film according to the present invention comprises an intermediate layer formed by laminating a first layer and a second layer on a metal substrate via a diffusion prevention layer and a bed layer. The first layer and the second layer have a rock salt structure and a fluorite structure, respectively, the first layer is <111> oriented and the second layer is <100> oriented. A method for producing a polycrystalline thin film, wherein the first layer and the second layer are formed by an ion beam assist method.
In order to solve the above-mentioned problems, the method for producing a polycrystalline thin film of the present invention has an intermediate layer formed by laminating a first layer and a second layer on a metal substrate via a single diffusion prevention layer. The crystal structures of the first layer and the second layer are a rock salt structure and a fluorite structure, respectively, the first layer is <111> oriented, and the second layer is <100> oriented. A method for producing a crystalline thin film, wherein the first layer and the second layer are formed by an ion beam assist method.

In order to solve the above problems, the oxide superconducting conductor of the present invention comprises an intermediate layer formed by laminating a first layer and a second layer on a metal substrate via a diffusion prevention layer and a bed layer, and a cap. An oxide superconducting conductor having a layer and an oxide superconducting layer, wherein the crystal structure of the first layer and the second layer is a rock salt structure and a fluorite structure, respectively, and the first layer is <111> Oriented, wherein the second layer is <100> oriented.
In order to solve the above-described problems, the oxide superconducting conductor of the present invention includes an intermediate layer formed by laminating a first layer and a second layer on a metal substrate via a single diffusion prevention layer, and a cap layer. And an oxide superconducting conductor having an oxide superconducting layer, wherein the crystal structure of the first layer and the second layer is a rock salt structure and a fluorite structure, respectively, and the first layer has a <111> orientation The second layer is <100> oriented.

In the polycrystalline thin film and the method for producing the same of the present invention, the crystal structures of the first layer and the second layer are a rock salt structure and a fluorite structure, respectively, the first layer has a <111> orientation, and the second layer has a <100> orientation. By setting the orientation, the intermediate layer can be thinned while maintaining good crystal orientation. Thereby, the polycrystalline thin film which reduced the internal stress of the film | membrane and prevented the base material from curling can be provided.
In addition, since the intermediate layer can be made thinner than the conventional one while maintaining good crystal orientation, the production speed can be dramatically increased, and the production cost can be reduced. .
Furthermore, the structure in which the diffusion prevention layer and the bed layer are interposed between the metal substrate and the intermediate layer ensures the diffusion of the metal substrate constituent elements from the metal substrate toward the surface of the polycrystalline thin film. Can be suppressed.
Further, by adopting a structure in which a diffusion preventing layer is interposed between the metal substrate and the intermediate layer, it is possible to suppress the diffusion of the metal substrate constituent elements from the metal substrate toward the surface side of the polycrystalline thin film. it can.

In the oxide superconducting conductor of the present invention, the crystal structure of the first layer and the second layer forming the intermediate layer is a rock salt structure and a fluorite structure, respectively, so that the intermediate layer is maintained while maintaining good crystal orientation. It can be thinned. This can reduce the internal stress of the film and prevent the base material from being warped, and can provide an oxide superconducting conductor with good crystal orientation, high critical current density and good superconducting properties.
Furthermore, by adopting a structure in which a diffusion prevention layer and a bed layer are interposed between the metal substrate and the intermediate layer, the metal substrate structure is directed from the metal substrate to the oxide superconducting layer on the surface side of the polycrystalline thin film. As a result of reliably suppressing the diffusion of elements, the effect of improving the superconducting characteristics of the oxide superconducting layer can be obtained as a result of suppressing the diffusion of unnecessary elements to the oxide superconducting layer.

<First embodiment>
FIG. 1 is a diagram schematically showing an example of a polycrystalline thin film 10 according to the present invention.
The polycrystalline thin film 10 of the present invention comprises an intermediate layer 15 formed by laminating a first layer 13 and a second layer 14 via a diffusion prevention layer 9 and a bed layer 12 in this order on a metal substrate 11, The crystal structures of the first layer 13 and the second layer 14 are a rock salt structure and a fluorite structure, respectively, wherein the first layer is <111> oriented and the second layer is <100> oriented. And

  In the present invention, the intermediate layer 15 is a laminate of the first layer 13 and the second layer 14, and the crystal structures of the first layer 13 and the second layer 14 are a rock salt structure and a fluorite structure, respectively. By being <111> oriented and the second layer being <100> oriented, the intermediate layer 15 can be thinned while maintaining good crystal orientation. Thereby, the internal stress of a film | membrane is reduced and the polycrystalline thin film 10 which prevented the metal base material 11 from curling can be provided.

Examples of the first layer 13 having a rock salt structure include an oxide represented by the composition formula γO, a nitride represented by δN, and a carbide represented by εC. Here, γ represents a divalent, δ represents a trivalent, and ε represents a tetravalent metal element. Γ is particularly preferably an alkaline earth metal Be, Mg, Ca, Sr, or Ba, and δ and ε are particularly Ti or Zr. , Hf, V, Nb, Ta are preferable. The first layer 13 may be a configuration example including two or more in addition to the configuration example including one of these elements.
Examples of the second layer 14 having a fluorite structure include those represented by the composition formula (α ₁ O ₂ ) _2x (β ₂ O ₃ ) _(1-X) . Here, α is Zr, Hf, Ti or a tetravalent rare earth element (for example, Ce), β is a trivalent rare earth element and belongs to 0 ≦ x ≦ 1, and in particular α is Zr. , Hf, 0.4 ≦ x ≦ 1.0 is desirable.

Specifically, the intermediate layer 15 having good orientation can be formed thinner by forming the IBAD intermediate layer 15 having different characteristics into a structure in which two types of layers are combined. Conventionally, an intermediate layer 15 (second layer 14 in this embodiment) made of Gd ₂ Zr ₂ O ₇ (hereinafter abbreviated as “GZO”) having a fluorite structure, which has conventionally required a thickness of 1000 nm or more, is formed of rock salt. By combining with the intermediate layer 15 made of MgO having a structure (the first layer 13 in this embodiment), the half-value width (Δφ) of crystal axis dispersion in the in-plane direction is set to 15 degrees or less with a thickness of 300 nm or less. Can do. Therefore, since the thickness is less than half that of the prior art, the manufacturing speed can be dramatically increased, and the manufacturing cost can be reduced.

  In addition, since the intermediate layer 15 (second layer 14) made of GZO having a fluorite structure is laminated, the intermediate layer 15 (first layer 13) made of MgO has an in-plane half of a thickness of 30 nm or more. Even when the value width is about 15 degrees or more, when an oxide superconducting layer (for example, YBCO) is formed on the polycrystalline thin film 10, good orientation and high characteristics can be obtained in the oxide superconducting layer. And a stable yield can be obtained.

  In the present embodiment, the metal base material 11 is in the form of a tape. However, the present invention is not limited to this, and various shapes such as a plate material, a wire material, and a strip can be used. For example, silver, Examples include various metal materials such as platinum, stainless steel, copper, nickel alloys such as Hastelloy, or various ceramic materials arranged on various metal materials.

The diffusion preventing layer 9 is formed for the purpose of preventing the diffusion of the constituent elements of the metal substrate 11 and is made of silicon nitride (Si ₃ N ₄ ), aluminum oxide (Al ₂ O ₃ , also referred to as “alumina”) or the like. Composed.

The bed layer 12 has high heat resistance and is intended to further reduce interfacial reactivity, and functions to obtain the orientation of the coating film disposed thereon. Such a bed layer 12 is arranged as necessary, and for example, a rare earth oxide layer can be used. For example, as the rare earth oxide, a composition formula (α ₁ O ₂ ) _2x (β ₂ O ₃ ) _{(1 -X)} . Here, α and β are rare earth elements belonging to 0 ≦ x ≦ 1. More specifically, Y ₂ O ₃ , CeO ₂ , Dy ₂ O ₃ , Er ₂ O ₃ , Eu ₂ O ₃ , Ho ₂ O ₃ , La ₂ O ₃ , Lu ₂ O ₃ , Nd ₂ O ₃ , Pr Examples include ₆ O ₁₁ , Sc ₂ O ₃ , Sm ₂ O ₃ , Tb ₄ O ₇ , Tm ₂ O ₃ , Yb ₂ O _{3 and the} like.
This bed layer is formed by, for example, a sputtering method, and the thickness thereof is, for example, 10 to 100 nm.
In the case of the two-layer structure of the diffusion prevention layer 9 and the bed layer 12, a structure in which the diffusion prevention layer 9 is made of alumina and the bed layer 12 is formed of Y ₂ O ₃ can be exemplified.
In the present invention, the diffusion prevention layer 9 and the bed layer 12 are not limited to the two-layer structure, but a single-layer structure including only the diffusion prevention layer 9 as shown in FIG. This structure will be described in a second embodiment described later.

The two-layer structure of the diffusion prevention layer 9 and the bed layer 12 as in this embodiment is inevitably required when an oxide superconducting layer or a cap layer is formed on the bed layer 12 as will be described in the following embodiments. When a thermal history is received as a result of being heated or heat-treated, it is possible to suppress diffusion of some of the constituent elements of the metal substrate 11 to the oxide superconducting layer side through the diffusion prevention layer 9 and the bed layer 12. Therefore, element diffusion from the metal substrate 11 side can be effectively suppressed by adopting a two-layer structure of the diffusion preventing layer 9 and the bed layer 12.
Further, since the crystal orientation of the diffusion preventing layer 9 and the bed layer 12 is not particularly limited, it may be formed by a film forming method such as a normal sputtering method.

The intermediate layer 15 is composed of a stacked body of the first layer 13 and the second layer 14.
The first layer 13 has a crystal salt structure. Examples of the material having such a rock salt structure include MgO.
The second layer 14 has a fluorite structure in crystal structure. Examples of the material having such a fluorite structure include YSZ and GZO.

As shown in FIG. 1, in the intermediate layer 15 forming the polycrystalline thin film 10, the first layer 13 and the second layer 14 have different orientation axes, the first layer 13 is <111> oriented, and the second layer 14 Is <100> oriented. In this way, by making the orientation axes of the first layer 13 and the second layer 14 different, the degree of freedom in selecting the material of the first layer and the specifications of the film structure can be greatly increased. .
In this example, even if the first layer 13 is a <111> -oriented film, the second layer 14 is <100> -oriented. In-plane orientation control can be carried out without problems. At this time, since the first layer 13 has a function of fixing the in-plane shaft of the second layer 14, the thickness of the second layer 14 can be made extremely thinner than before.

  When an oxide superconducting layer (for example, YBCO) is formed on the polycrystalline thin film 10, the MgO intermediate layer 15 (first layer 13) is adopted by adopting the <111> -oriented MgO intermediate layer 15 (first layer 13). Even if 13) has a thickness of 30 nm or more, good orientation and high characteristics can be obtained in the oxide superconducting layer, and a stable yield can be obtained.

In this case, the thickness of the first layer 13 is preferably in the range of 5 to 200 nm, and the thickness of the second layer 14 is preferably in the range of 100 to 300 nm. If the thickness of the first layer is less than 5 nm, it is difficult to maintain the film thickness stably, and there is a possibility that the film thickness varies. When an oxide superconducting layer is formed on the polycrystalline thin film 10, the lower limit value of the thickness of the second layer 14 also depends on the thickness of the cap layer 11 (CeO ₂ layer) formed thereon. The thickness may be 10 nm or more, preferably 50 nm or more, and more preferably 100 nm or more. When the thickness is less than 10 nm, even if a CeO ₂ layer is deposited thereon, the degree of orientation becomes 10 degrees or more, and a sufficient critical current does not flow.

On the other hand, when the total thickness of the first layer 13 and the second layer 14 exceeds 500 nm, the internal stress of the first layer 13 and the second layer 14 increases, and thereby the internal stress of the entire polycrystalline thin film 10 increases. The polycrystalline thin film 10 is not preferable because it easily peels from the metal substrate 11. On the other hand, if the thickness exceeds 500 nm, the surface roughness increases and the critical current density decreases, which is not preferable.
The film thicknesses of the first layer 13 and the second layer 14 can be increased or decreased by adjusting the delivery speed of the metal substrate 11.

  The second layer 14 is preferably composed of an initial portion oriented <111> and a growth portion oriented <100>. Thereby, the interface between the <111> -oriented first layer 13 and the second layer 14 is stabilized. Therefore, the <100> -oriented second layer 14 is formed on the <111> -oriented first layer 13 through the <111> -oriented initial portion of the second layer 14 with high reproducibility and wide production conditions. Can be formed. From the initial part of the second layer 14 to the growth part, the axis is tilted in the stacking direction of the first layer 13 and the second layer 14 and gradually becomes <100> oriented from <111> orientation.

<Second Embodiment>
Next, a second embodiment of the polycrystalline thin film of the present invention will be described. In the following description, portions different from those of the first embodiment described above will be mainly described, and description of similar portions will be omitted.
FIG. 2 is a diagram schematically showing an example of the polycrystalline thin film 20 according to the present invention.
The polycrystalline thin film 20 of the present embodiment is formed by forming an intermediate layer 25 formed by laminating a first layer 23 and a second layer 24 on a metal substrate 21 with a diffusion preventing layer 22 interposed therebetween. And
In the structure of the present embodiment, an example in which one diffusion prevention layer 22 is provided between the metal substrate 21 and the intermediate layer 25 is shown. The structure of the second embodiment is different from the structure of the first embodiment in that the bed layer is omitted.

As in the first embodiment, a two-layer structure of the diffusion prevention layer 9 and the bed layer 12 is desirable in terms of prevention of diffusion. However, if the number of layers is increased, it takes a longer film formation time. In the case of a tape-like wire having a length of several hundreds of meters, such as an oxide superconducting conductor, the bed layer 12 can be omitted and only the diffusion preventing layer 22 can be used in order to shorten the entire manufacturing time as much as possible. is there.
As in the case of the first embodiment, alumina is preferably used for the diffusion preventing layer 22 used in that case.
Further, a Gd ₂ Zr ₂ O ₇ layer can be used as the rare earth metal oxide layer constituting the diffusion preventing layer 22. In this case, since the crystal orientation is not particularly limited, the diffusion preventing layer 22 may be formed by a film forming method such as a normal sputtering method as in the case of the first embodiment. In particular, if a Gd ₂ Zr ₂ O ₇ layer is used as the diffusion preventing layer 22, a diffusion preventing effect close to the two-layer structure of the diffusion preventing layer 9 and the bed layer 12 of the first embodiment can be obtained. This is advantageous because the superconducting properties of the oxide superconducting layer formed in the above are improved.
If a special film formation method such as the IBAD method is used for adjusting the crystal orientation of the diffusion preventing layer 22, the film formation rate is lowered and the film formation takes time. As long as the prevention layer 22 is used, crystal orientation is not an issue, and a normal sputtering method having a high film formation rate can be selected and used. There is little risk of lengthening.

<Structure of oxide superconducting conductor>
Next, an oxide superconductor using the polycrystalline thin film as described above will be described.
FIG. 3 is a diagram schematically showing an example of the oxide superconducting conductor according to the present invention.
The oxide superconducting conductor 30 of this embodiment includes an intermediate layer 35 formed by laminating a first layer 33 and a second layer 34 via a diffusion prevention layer 29 and a bed layer 32 in this order on a metal substrate 31. An oxide superconducting conductor in which a cap layer 37 and an oxide superconducting layer 38 are stacked at least on top of each other, and the first layer 33 and the second layer 34 are respectively the first layer 13 of the first embodiment, The structure is the same as that of the second layer 14.

  In this embodiment, the crystal structure of the first layer 33 and the second layer 34 forming the intermediate layer 35 in the polycrystalline thin film is a rock salt structure and a fluorite structure, respectively, and the first layer 33 is <111> oriented, By making the second layer 34 be <100> oriented, the intermediate layer can be thinned while maintaining good crystal orientation. As a result, the internal stress of the film can be reduced, the substrate can be prevented from warping, and the oxide superconducting conductor having good crystal orientation, high critical current density and good superconducting properties can be provided.

The cap layer 37 is composed of a CeO ₂ layer. Further, this CeO ₂ layer does not need to be entirely made of CeO _2, and may contain a Ce—M—O-based oxide in which part of Ce is partially substituted with another metal atom or metal ion. . The CeO ₂ layer can be formed by a PLD method (pulse laser deposition method), a sputtering method, or the like, but it is desirable to use the PLD method from the viewpoint of obtaining a high film formation rate. As conditions for forming the CeO ₂ layer by the PLD method, a laser energy density of 1 to 5 J / cm ² can be performed in an oxygen gas atmosphere at a substrate temperature of about 500 to 800 ° C. and about 0.6 to 40 Pa. .
The film thickness of the CeO ₂ layer may be 50 nm or more, but is preferably 100 nm or more, and more preferably 500 nm or more in order to obtain sufficient orientation. However, if it is too thick, the crystal orientation deteriorates, so it is preferable to set the thickness to 500 to 600 nm.

As a material of the oxide superconducting layer 38, an RE-123 oxide superconductor (REBa ₂ Cu ₃ O _7-X : RE is a rare earth element such as Y, La, Nd, Sm, Eu, and Gd) is used. it can. The RE-123-based oxide is preferably Y123 (YBa ₂ Cu ₃ O _7-X : hereinafter referred to as “YBCO”) or Sm123 (SmBa ₂ Cu ₃ O _7-X , hereinafter referred to as “SmBCO”). It is.

The oxide superconducting layer 38 can be formed by a normal film forming method. From the viewpoint of productivity, the TFA-MOD method (metal organic deposition method using trifluoroacetate, coating pyrolysis method), PLD method or CVD method is preferably used.
The MOD method is a method in which a metal organic acid salt is applied and then thermally decomposed. After a solution in which a metal component organic compound is uniformly dissolved is applied on a substrate, the substrate is heated and thermally decomposed. This is a method of forming a thin film on top, and is suitable for the production of a long tape-shaped oxide superconducting conductor because it does not require a vacuum process and enables high-speed film formation at low cost.

  Here, as described above, when the oxide superconducting layer 37 is formed on the polycrystalline thin film 36 having a good orientation, the oxide superconducting layer 37 laminated on the polycrystalline thin film 36 is also aligned with the polycrystalline thin film 1. Crystallize to match sex. Therefore, the oxide superconducting layer 37 formed on the polycrystalline thin film 36 is hardly disturbed in crystal orientation, and in each of the crystal grains constituting the oxide superconducting layer 37, the metal base 31 The c-axis in which electricity is difficult to flow is oriented in the thickness direction, and the a-axis or b-axis is oriented in the length direction of the metal substrate 2. Therefore, the obtained oxide superconducting layer 12 is excellent in the quantum connectivity at the crystal grain boundary, and hardly deteriorates the superconducting property at the crystal grain boundary, so that it is easy to flow electricity in the length direction of the metal base 2. A sufficiently high critical current density is obtained.

  As described above, in the present invention, an intermediate layer with good orientation can be formed thinner by combining IBAD intermediate layers having different crystal structures in a polycrystalline thin film. By combining a MgO intermediate layer (first layer) having a rock salt structure with an intermediate layer (second layer) made of GZO having a fluorite structure, which conventionally required a thickness of 1000 nm or more, a thickness of 300 nm or less The intermediate layer 35 having an in-plane half width of 15 degrees or less in thickness can be provided. Thereby, the internal stress of a film | membrane is reduced and the curvature of a metal base material can be prevented.

The polycrystalline thin film and the oxide superconducting conductor of the present invention have been described above. However, the present invention is not limited to this, and can be appropriately changed as necessary.
For example, in the present embodiment, the case where a polycrystalline thin film is applied to an oxide superconducting conductor has been described. However, the present invention is not limited to this. The present invention can be applied to any of thin film for wiring, a dielectric thin film used for a high frequency waveguide, a high frequency filter, a cavity resonator, and the like.

That is, if these thin films are formed on a polycrystalline thin film having good crystal orientation by sputtering, laser deposition, vacuum deposition, CVD (chemical vapor deposition) or the like, good consistency with the polycrystalline thin film. Since these thin films are deposited or grown, the orientation becomes good.
These thin films provide high-quality thin films with good orientation, so optical films are excellent in optical characteristics, magnetic films are excellent in magnetic characteristics, and wiring thin films are free from migration. Can provide a thin film with good dielectric properties.

First, a film forming apparatus using the IBAD method used in this embodiment will be described.
FIG. 4 shows an example of an apparatus for manufacturing a polycrystalline thin film, and the apparatus of this example has a configuration in which an ion gun for ion beam assist is provided in a sputtering apparatus.
The film forming apparatus includes a base material holder 51 that holds the base material A horizontally, a plate-like target 52 that is disposed diagonally above the base material holder 51 at a predetermined interval, and an oblique position of the base material holder 51. It is mainly configured by an ion gun 53 that is opposed to the upper side at a predetermined interval and is spaced apart from the target 52, and a sputter beam irradiation device 54 that is disposed below the target 52 and toward the lower surface of the target 52. Yes. Reference numeral 55 in the drawing denotes a target holder that holds the target 52.
The apparatus is housed in a vacuum container (not shown) so that the periphery of the substrate A can be maintained in a vacuum atmosphere. Further, an atmospheric gas supply source such as a gas cylinder is connected to the vacuum container, the inside of the vacuum container is in a low pressure state such as a vacuum, and an inert gas containing argon gas or other inert gas atmosphere or oxygen The atmosphere can be changed.

When a long metal tape is used as the base material A, a metal tape feeding device and a winding device are provided inside the vacuum container, and the base material A is continuously fed from the feeding device to the base material holder 51. Subsequently, it is preferable that the polycrystalline thin film be continuously formed on the tape-shaped substrate by winding with a winding device.
The base material holder 51 includes a heater inside, and the base material A positioned on the base material holder 51 can be heated to a desired temperature. In addition, an angle adjustment mechanism that can adjust the horizontal angle of the substrate holder 51 is attached to the bottom of the substrate holder 51. An angle adjustment mechanism may be attached to the ion gun 53 to adjust the tilt angle of the ion gun 53 to adjust the ion irradiation angle.

The target 52 is used to form a target polycrystalline thin film, and a target having the same or approximate composition as the polycrystalline thin film having the target composition is used. Specifically, MgO, GZO, or the like is used as the target 52, but is not limited thereto, and a target that matches the polycrystalline thin film to be formed may be used.
The ion gun 53 is configured such that a gas to be ionized is introduced into a container and a lead electrode is provided on the front surface. And it is an apparatus which ionizes one part of the atom or molecule | numerator of gas, and irradiates the ionized particle | grain as an ion beam controlled by the electric field generated with the extraction electrode. There are various types of ionization of gas, such as a high frequency excitation method and a filament type. The filament type is a method in which a tungsten filament is energized and heated to generate thermoelectrons and collide with gas molecules in a high vacuum to be ionized. The high-frequency excitation method ionizes gas molecules in a high vacuum by polarization with a high-frequency electric field.
In this embodiment, an ion gun 53 having an internal structure shown in FIG. 5 is used. The ion gun 53 includes an extraction electrode 57, a filament 58, and an introduction tube 59 for Ar gas or the like inside a cylindrical container 56, and can irradiate ions in parallel in a beam shape from the tip of the container 56. It is.

As shown in FIG. 4, the ion gun 53 is opposed to the upper surface (film formation surface) of the substrate A with an inclination angle θ. The inclination angle θ is preferably in the range of 30 to 60 degrees, but in the case of MgO, around 45 degrees is particularly preferable. Accordingly, the ion gun 53 is arranged so as to irradiate ions with an inclination angle θ with respect to the upper surface of the substrate A. The ions irradiated onto the substrate A by the ion gun 53 may be ions of rare gases such as He ⁺ , Ne ⁺ , Ar ⁺ , Xe ⁺ , Kr ⁺ , or mixed ions of these and oxygen ions.
The sputter beam irradiation device 54 has the same configuration as that of the ion gun 53, and can irradiate ions on the target 52 to knock out the constituent particles of the target 52. In the device of the present invention, since it is important that the constituent particles of the target 53 can be knocked out, a voltage is applied to the target 52 with a high-frequency coil or the like so that the constituent particles of the target 52 can be knocked out. The sputter beam irradiation device 54 may be omitted.

Next, the case where a polycrystalline thin film is formed on the base material A using the apparatus having the above configuration will be described.
In order to form a polycrystalline thin film on the substrate A, a predetermined target is used, and the angle adjustment mechanism is adjusted to irradiate the upper surface of the substrate holder 51 with ions irradiated from the ion gun 53 at an angle of about 45 degrees. It can be so. Next, the inside of the container containing the substrate is evacuated to form a reduced pressure atmosphere. Then, the ion gun 53 and the sputter beam irradiation device 54 are operated.

  When the target 52 is irradiated with ions from the sputter beam irradiation device 54, the constituent particles of the target 52 are knocked out and fly onto the substrate A. Then, the constituent particles knocked out from the target 52 are deposited on the substrate A, and at the same time, a mixed ion of Ar ions and oxygen ions is irradiated from the ion gun 53. The irradiation angle θ at the time of ion irradiation is preferably in the range of 40 to 60 degrees, for example, when forming MgO.

"Production Example 1"
As the metal substrate, a 10 mm wide Hastelloy tape whose surface was polished was used. A thin yttria film (Y ₂ O ₃ film) (about 20 nm) was formed on this metal substrate by sputtering, and then an MgO film (about 200 nm) was formed by IBAD as the first layer constituting the intermediate layer. .
Next, a GZO film having a thickness of about 200 nm was stacked on the MgO film by the IBAD method as a second layer constituting the intermediate layer. At this time, the MgO film and the GZO film were produced while performing ion beam assist with a rare gas ion beam of Ar or the like at a substrate temperature of 200 ° C. or lower.

Further, a CeO ₂ film having a thickness of 500 nm was formed on the GZO film by the PLD method. With respect to the MgO film, the GZO film, and the CeO ₂ film thus obtained, the half width of crystal axis dispersion in the in-plane direction was measured. The results are shown in Table 1 (Samples 1 to 4).
As a comparative example, only a GZO film was formed as an intermediate layer, and a CeO ₂ film having a thickness of 500 nm was formed on the GZO film by a PLD method. The half-value width measurement results in this case are also shown in Table 1 (Samples 5 and 6).

Under appropriate film formation conditions, the <111> axis is oriented perpendicular to the base material of the MgO film, the <100> axis is oriented in the ion beam direction, and the in-plane crystal axis is within a half width of 20 degrees. A thin film having this structure is characterized by being formed with a similar structure under a wide range of conditions, and the film thickness can be changed to about 5 to 200 nm.
In order to obtain a high-performance superconducting layer, it is necessary that the c-axis of the superconducting layer is oriented perpendicular to the substrate and the half-value width of the in-plane crystal axis is within 10 degrees. In order to obtain such a superconducting layer by lattice matching with the intermediate layer, an intermediate layer in which the <100> axis is vertically oriented and the half width of the in-plane crystal axis is within 10 degrees is formed in a cubic material. It is essential to do. As a method for stably obtaining this, a fluorite structure-based intermediate layer made of GZO was laminated by the IBAD method. Thus, an intermediate layer (second layer) made of GZO having a half-value width of about 10 degrees and a <100> axis vertically oriented on an intermediate layer (first layer) made of <111> -oriented MgO with a half-width of 20 degrees. Layer) was successfully grown (sample 4).
Up to now, there has been no example in which an intermediate layer having an orientation structure clearly different from that of the first layer is aligned, and the present invention has opened the way to stably synthesize high-performance films stably under a wide range of conditions.

Further, in the CeO ₂ layer laminated on the intermediate layer made of GZO by the PLD method, the crystal axis dispersion in the in-plane direction has a half width of about 4 degrees.
That is, by comparing sample 3 and sample 5 in Table 1, in sample 5, the half-value width of 13.5 degrees was obtained at 1400 nm thickness in the intermediate layer made of GZO, whereas in sample 3, A full width at half maximum (14.2 degrees) as described above is obtained with a total thickness of 290 nm [intermediate layer made of MgO (30 nm) + intermediate layer made of GZO (260 nm)].
As described above, the polycrystalline thin film produced in Example 1 is formed by stacking (two layers) intermediate layers having different crystal structures, with the first layer being a rock salt structure and the second layer being a fluorite structure. It was confirmed that the half-width at the same level can be realized by an intermediate layer having a thickness of about 1/5. That is, according to the configuration of the present invention, since the intermediate layer forming the polycrystalline thin film can be made 1/5 of the film thickness, the internal stress of the film is reduced and the conventional problem of the substrate warping is solved. be able to. Furthermore, since the film thickness is 1/5, the manufacturing speed can be dramatically increased, and the manufacturing cost can be reduced.

Further, a YBCO superconducting layer was formed on the CeO ₂ layer to a thickness of 1000 nm by the PLD method. This YBCO superconducting layer is heat-treated in an oxygen atmosphere at 500 ° C. for 5 hours after film formation. As a result of evaluating the characteristics, it was confirmed that high characteristics of critical current density Jc = 2 MA / cm ² and critical current Ic = 200 A were obtained at liquid nitrogen temperature.
Next, in place of the structure of Test Example 1, a GZO film as a diffusion prevention layer was formed on a metal substrate of Hastelloy tape by a sputtering method to a thickness of about 20 μm, and Example 1 and Example 1 were formed on this diffusion prevention layer. A polycrystalline thin film was obtained by forming an equivalent structure, that is, an MgO film by IBAD method, a GZO film by IBAD method as a second layer, and a CeO ₂ film by PLD method. That is, the film thickness and film formation conditions of each film were the same as those in Test Example 1.
As a result of measuring the in-plane axial dispersion half-value width equivalent to that of Example 1 for the polycrystalline thin film having this structure, a result equivalent to the result shown in Table 1 could be obtained.
Further, a YBCO superconducting layer was formed to a thickness of 1000 nm on the CeO ₂ layer of the polycrystalline thin film by a PLD method to obtain an oxide superconducting conductor. As a result of evaluating the characteristics, it was confirmed that high characteristics of critical current density Jc = 3 MA / cm ² and critical current Ic = 300 A were obtained at liquid nitrogen temperature.
Since these values exhibit superconducting properties superior to those of the oxide superconducting conductor using the yttria film (Y ₂ O ₃ film) (about 20 nm), in the GZO film, the heat during heat treatment It seems to be the result that the element diffusion from the metal base material can be more effectively suppressed during the history.

Next, instead of the single layer structure of the yttria film or the GZO film, a two-layer laminated structure of an alumina film (thickness 100 nm) and an yttria film (Y ₂ O ₃ film) (about 20 nm) is employed on a metal substrate. Thus, a polycrystalline thin film was formed. Both the alumina film and the yttria film were formed by sputtering.
A YBCO superconducting layer was formed to a thickness of 1000 nm by the PLD method on the obtained polycrystalline thin-film CeO ₂ layer to obtain an oxide superconducting conductor. As a result of evaluating the characteristics, it was confirmed that high characteristics of critical current density Jc = 3.5 MA / cm ² and critical current Ic = 350 A were obtained at the liquid nitrogen temperature.
From the above results, in comparison with the single layer structure, the GZO film is more advantageous as an element diffusion suppressing effect of the metal base constituent element than the yttria film, and the alumina film and the yttria film are more advantageous than the single layer structure. It has been clarified that the two-layer structure is more advantageous as an element diffusion suppressing effect of the metal base constituent elements.

Next, the conditions for forming the <111> -oriented first layer (MgO film) in the structure of Production Example 1 were examined.
In the same manner as in Production Example 1, after forming an yttria film on the metal substrate by sputtering, an MgO film (200 nm or less) was formed by IBAD as the first layer constituting the intermediate layer. At that time, the voltage of the sputter ion gun was fixed at 1500 V, and the current was 850 mA to 1000 mA. Moreover, the voltage of the assist ion gun was fixed to 800 V, and the current was set to 400 mA to 900 mA. The results are shown in Table 2.

In Table 2, the region B shown under white conditions indicates that a <111> -oriented MgO film was formed, and in the region A shown under gray, the <100> orientation was shown. This shows that the formed MgO film was formed.
FIG. 8 shows the conditions for forming the MgO film and the orientation axis direction. The horizontal axis is the current density of the assist ion beam, and the vertical axis is the half width of dispersion in the in-plane crystal axis direction of the MgO alignment film by the IBAD method. <111> orientation (3-fold) is obtained under most film formation conditions, and the <100> orientation film is formed only in a narrow region where the current density of the assist ion beam is about 100 μA / cm ^2. Recognize.
From Table 2 and FIG. 8, it can be seen that the <111> -oriented MgO film is formed under a wide range of conditions, whereas the <100> -oriented MgO film can be obtained only under certain limited conditions. It was. Therefore, a <111> -oriented MgO film can be formed with a wider margin than a <100> -oriented MgO film.

Next, a cross-sectional image when a GZO film was formed on the <111> -oriented MgO film by the IBAD method in the same manner as in Example 1 was observed with a transmission electron microscope (hereinafter referred to as TEM). The results are shown in FIGS.
FIG. 9 shows a dark field cross-sectional TEM image of a sample in which an yttria film (Y ₂ O ₃ film), an MgO film by an IBAD method, and a GZO film are provided in this order on a metal substrate. Note that a Pt film is formed on the GZO film so that a section of the sample can be stably produced when the cross section is observed with a TEM. FIG. 10 shows a diffraction image of the electron beam irradiated on the GZO film after being focused. The dark field TEM image in FIG. 9 is a mapping based on the signal obtained by extracting the GZO (004) diffraction peak. The portion that appears bright indicates that the GZO film is oriented <100> perpendicular to the substrate. It can be seen that the portion near the upper film surface is very bright and is strongly <100> oriented. On the other hand, since it is dark at a thickness of about 150 nm near the interface, it can be seen that there are almost no <100> oriented crystal grains in this region. When the diffraction image of FIG. 10 in which the entire GZO film is irradiated with an electron beam is seen, in addition to the (004) diffraction peak, the (222) diffraction peak is seen, so that the (222) -oriented crystal grains are located near the interface. The possibility exists.

FIG. 11 is a bright field TEM image in which a part of FIG. 9 is enlarged. FIG. 11A is an image from a metal base material to an overlapped portion from the yttria film, the MgO film, and the GZO film. FIG. 11B is an enlarged high-resolution image showing a part of the interface between the MgO film and the GZO film.
Because of the high resolution, the crystal structure can be confirmed directly from the atomic image, and the orientation can be specified. From FIG. 10B, it can be confirmed that in the vicinity of the interface, both the MgO film and the GZO film have a structure in which the <111> axes are arranged vertically.
9 to 11, the structure of this example shows that the initial portion of the <111> -oriented GZO film is first laminated on the <111> -oriented MgO film, and then the <100> -oriented GZO film is formed. Growing structure was confirmed. By producing with this structure, it is possible to utilize the wide MgO film formation conditions shown in Table 2 and FIG.

"Production Example 2"
As the metal substrate, a 10 mm wide Hastelloy tape whose surface was polished was used. A thin yttria (Y ₂ O ₃ ) film (about 20 nm) was formed on this metal substrate by sputtering, and then an MgO film (200 nm or less) was formed by IBAD as the first layer constituting the intermediate layer.
Next, a GZO film having a thickness of about 200 nm was stacked on the MgO film by the IBAD method as a second layer constituting the intermediate layer. At this time, the MgO film and the GZO film were produced while performing ion beam assist with a rare gas ion beam of Ar or the like at a substrate temperature of 200 ° C. or lower.

Further, a CeO ₂ film having a thickness of 500 nm was formed on the GZO film by the PLD method. With respect to the MgO film, the GZO film, and the CeO ₂ film thus obtained, the half width of crystal axis dispersion in the in-plane direction was measured.
As a result, the polycrystalline thin film produced in Production Example 2 also has the same tendency as the polycrystalline thin film in Production Example 1 described above, that is, an intermediate layer having a different crystal structure is laminated (two layers). It was confirmed that by using a rock salt structure and a fluorite structure as the second layer, an intermediate layer with a half-width at the same level as the conventional one can be realized. Therefore, even in the case of the polycrystalline thin film produced in Production Example 2, the internal stress of the film is reduced and the conventional problem of warping of the substrate can be solved. Furthermore, since the film thickness is extremely thin, the manufacturing speed can be dramatically increased, and the manufacturing cost can be reduced.

More specifically, under appropriate film forming conditions, the MgO film has a <100> axis oriented perpendicular to the substrate, a <110> axis oriented in the ion beam direction, and the in-plane crystal axis has a half-width of 10 degrees. It turned out to be within. However, this condition is narrow. For example, when the film thickness exceeds 10 nm, the full width at half maximum spreads rapidly, and when the thickness is 50 nm, it reaches about 15 degrees.
In order to obtain a superconducting layer having high characteristics, the half width must be within 10 degrees. As a method for stably obtaining this, a fluorite-structure-type intermediate layer made of GZO was laminated by the IBAD method. This succeeded in growing a <100> -oriented GZO intermediate layer with a half-value width of 10 degrees on an <100> -oriented MgO intermediate layer with a half-value width of 15 degrees.
Further, by laminating the CeO ₂ layer with a thickness of 500 nm by the PLD method, the crystal axis dispersion in the in-plane direction became about 4 degrees half-value width.

In addition, a YBCO superconducting layer having a thickness of 1000 nm was formed on the CeO ₂ layer by the PLD method. As a result of evaluating the characteristics, it was confirmed that high characteristics of critical current density Jc = 2 MA / cm ² and critical current Ic = 200 A were obtained at liquid nitrogen temperature.

Next, the conditions for forming the <100> -oriented first layer (MgO film) were examined.
As in Production Example 2, after forming an yttria film on the metal substrate by sputtering, an MgO film (200 nm or less) was formed by the IBAD method as the first layer constituting the intermediate layer. At that time, the voltage of the sputter ion gun was fixed at 1500 V, and the current was 850 mA to 1000 mA. Moreover, the voltage of the assist ion beam was fixed at 800 V, and the current was set to 400 mA to 900 mA. The results are shown in Table 2 as in Example 1.
Table 2 shows that a <100> -oriented MgO film can be obtained only under specific limited conditions.

Next, in the above-described examination of the conditions of the MgO film, a sample in which the yttria (Y ₂ O ₃ ) film as the diffusion preventing layer on the metal substrate is replaced with a GZO film, and the yttria as the diffusion preventing layer on the metal substrate. Samples in which the (Y ₂ O ₃ ) film was replaced with a two-layer laminated structure of an alumina film and an yttria film were prepared and examined for the same conditions as described above. The same tendency was shown.
From the above results, even if the yttria (Y ₂ O ₃ ) film as the diffusion preventing layer is replaced with a GZO film or a two-layer laminated structure of an alumina film and an yttria film, the MgO intermediate layer and the GZO film thereon are equivalent. <111> orientation and <100> orientation were shown. Regarding the crystal orientation of the MgO film and the GZO film by the IBAD method, the single layer of the yttria film is used even when the base is a single GZO film by the normal sputtering method and the base is a two-layer structure of an alumina film and an yttria film. It was found that it is possible to obtain the same result as in the case of.

"Production Example 3"
Instead of the yttria (Y ₂ O ₃ ) film used in Production Example 1, an alumina (Al ₂ O ₃ ) film is formed on a metal substrate, and a first layer having a structure equivalent to that of Production Example 1 is formed thereon. An MgO film (about 200 nm thick) by the IBAD method was formed, and a GZO film (about 250 nm thick) by the IBAD method was stacked as the second layer. The half width of the in-plane crystal axis of this GZO film was 17 °.
Thus on the GZO film, when 500nm laminated form CeO ₂ film by a PLD method, it is possible to obtain excellent alignment property of the CeO ₂ film of about 4 ° equivalent to the previous Preparation Example 1.
FIG. 12 shows an MgO (110) positive electrode dot diagram of an MgO film (about 200 nm thick) formed by the IBAD method on the alumina film.
From this figure, the present invention is similar to the case of the previous yttria film also by using an alumina film instead of the yttria film, that is, not by the combination of the diffusion prevention layer and the bed layer but by the structure of only the diffusion prevention layer. It was revealed that the desired excellent orientation could be realized.
FIG. 13 is a (222) positive electrode dot diagram of the GZO film formed by the IBAD method. From the pole figure of FIG. 13, it is clear that the excellent orientation aimed at by the present invention is obtained.

It is a figure which shows typically an example of the polycrystalline thin film which concerns on this invention. It is a figure which shows typically an example of the polycrystalline thin film which concerns on this invention. It is a figure which shows typically an example of the oxide superconducting conductor which concerns on this invention. It is a figure which shows typically the film-forming apparatus by IBAD method. It is a figure which shows typically the ion gun with which the film-forming apparatus shown in FIG. 4 is provided. It is a figure which shows typically an example of the conventional polycrystalline thin film. It is a figure which shows typically an example of the conventional polycrystalline thin film. It is the figure which showed the film-forming conditions and orientation axis direction of a MgO film | membrane. It is a figure which shows the cross-sectional TEM image of the interface of a MgO film | membrane and a GZO film | membrane. It is a figure which shows the cross-sectional TEM image of the growth part of the GZO film | membrane formed on the <111> oriented MgO film | membrane. It is a figure which shows the diffraction peak of the GZO film | membrane formed on the <111> oriented MgO film | membrane. The (110) positive electrode dot figure of the MgO film | membrane formed on the alumina film | membrane. The (222) positive electrode dot figure of the GZO film | membrane by IBAD method formed on the MgO film | membrane.

Explanation of symbols

  9, 22, 29 ... Diffusion prevention layer, 10, 20, 36 ... Polycrystalline thin film, 11, 21, 31 ... Metal substrate, 12, 32 ... Bed layer, 13, 23, 33 ... First layer, 14, 24 34 ... second layer, 15, 25, 35 ... intermediate layer, 30 ... oxide superconducting conductor, 37 ... cap layer, 38 ... oxide superconducting layer.

Claims (7)

  An intermediate layer formed by laminating a first layer and a second layer via a diffusion prevention layer and a bed layer on a metal substrate, and the crystal structures of the first layer and the second layer are rock salt A polycrystalline thin film having a structure and a fluorite structure, wherein the first layer is <111> oriented and the second layer is <100> oriented.   On the metal substrate, it has an intermediate layer formed by laminating the first layer and the second layer through one diffusion prevention layer, and the crystal structure of the first layer and the second layer is a rock salt structure, respectively. And a fluorite structure, wherein the first layer is <111> oriented and the second layer is <100> oriented.   3. The polycrystalline thin film according to claim 1, wherein the second layer includes a <111> -oriented initial portion and a <100> -oriented growth portion. An intermediate layer formed by laminating a first layer and a second layer via a diffusion prevention layer and a bed layer on a metal substrate, and the crystal structures of the first layer and the second layer are rock salt A method of producing a polycrystalline thin film having a structure and a fluorite structure, wherein the first layer is <111> oriented and the second layer is <100> oriented,
The method for producing a polycrystalline thin film, wherein the first layer and the second layer are formed by an ion beam assist method. On the metal substrate, it has an intermediate layer formed by laminating the first layer and the second layer through one diffusion prevention layer, and the crystal structure of the first layer and the second layer is a rock salt structure, respectively. A method of manufacturing a polycrystalline thin film in which the first layer is <111> oriented and the second layer is <100> oriented,
The method for producing a polycrystalline thin film, wherein the first layer and the second layer are formed by an ion beam assist method. An oxide superconducting conductor having an intermediate layer formed by laminating a first layer and a second layer via a diffusion prevention layer and a bed layer, a cap layer, and an oxide superconducting layer on a metal substrate. ,
The crystal structures of the first layer and the second layer are a rock salt structure and a fluorite structure, respectively, the first layer is <111> oriented, and the second layer is <100> oriented. Oxide superconducting conductor. An oxide superconducting conductor having an intermediate layer formed by laminating a first layer and a second layer, a cap layer, and an oxide superconducting layer on a metal substrate via one diffusion prevention layer,
The crystal structures of the first layer and the second layer are a rock salt structure and a fluorite structure, respectively, the first layer is <111> oriented, and the second layer is <100> oriented. Oxide superconducting conductor.

Images