JP2979422B2 - Method of manufacturing insulator and insulating thin film, and method of manufacturing superconducting thin film and superconducting thin film - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to an insulator which is indispensable when a material such as an oxide high-temperature superconductor that undergoes a relatively high production process at 600 to 900 ° C. is made into a device. More specifically, the present invention relates to a superconducting thin film having higher performance and a method for producing a superconducting thin film.

(Prior Art) At present, one of the most urgently applied materials is an oxide high-temperature superconductor. This perovskite compound is expected to have a higher transition temperature than the metal compound superconductor,
Ba-La-Cu-O high-temperature superconductors have been proposed [JGBe
dnorz and KAMuller, Zeitschrift Fur
Fijik (Zetshrift Fur Physik B)-Condensed Ma
tter, Vol. 64, 189-193 (1986)]. Further, Bi-Sr-Ca
H-Maeda, Y.Tanaka, M.Fukutomi and T.Asan have also discovered that -Cu-O-based materials exhibit a transition temperature of 100 ° K or more.
o, Japanese Journal of Applied Physics Vo
l.27, L209-210 (1988)]. Although the details of the superconducting mechanism of this type of material are not clear, the transition temperature may be higher than room temperature, and it is expected to be applied in the field of electronic devices as a high-temperature superconductor compared to conventional binary compounds. Have been.

And, coupled with the development of these oxide superconductors,
Considering the application of this material to electronic devices, development of insulators and insulating thin films that are stable against the high heat process that occurs when fabricating oxide superconductors is being conducted [Y. Ichikawa, HA
dachi, T.Mitsuyu and K.Wasa, Japanese Journal of Applied Physics (Japanese Journ
al of Applied Physics) Vol.27, L381-383 (198
8)].

Furthermore, a higher superconducting transition temperature has been conventionally expected by alternately laminating a superconductor and an insulator [MHCohen and DHDouglass, Jr., Physical Review Letters Vol.19 , L1
18-121 (1967)].

(Problems to be Solved by the Invention) However, the material of the oxide superconductor requires heat treatment of at least 600 ° C. or heating during formation in order to obtain good superconducting properties. Crystallinity collapses, interdiffusion of each element occurs between the insulator and the insulating thin film and the superconductor, and the properties of the superconductor and the insulator deteriorate. It is extremely difficult to obtain a periodic laminated structure with a film, and an integrated device using this structure, a typical example of which is the Josephson device, has been made almost impossible to configure.

In addition, because the optimum insulating thin film for high-temperature superconductors and thin films has not been obtained, an effective laminated structure of superconductor and insulator cannot be achieved. It was the present situation that we could not hope for.

An object of the present invention is to solve the conventional drawbacks, an insulator that is indispensable when converting a material that undergoes a relatively high production process such as an oxide high-temperature superconductor into a device, and a method for manufacturing an insulating thin film, An object of the present invention is to provide a superconducting thin film with higher performance and a method for producing the superconducting thin film.

(Means for Solving the Problems) The insulator according to the first invention is characterized in that the main components are at least bismuth (Bi), copper (Cu), calcium (Ca), alkaline earth (Group IIa), and Y and lanthanum. A series of at least one element, wherein the ratio of the elements is Bi: A: Ca: Ln: Cu = 2: 2: 1−y: y: 2 (0.5 ≦ y ≦ 0.75), (Where A is an alkaline earth and represents at least one or two or more elements of group IIa elements. Ln represents at least one element of Y or a lanthanide series element) ).

Further, the method for producing an insulating thin film according to the second invention relates to thinning of the insulator according to the first invention, wherein an oxide containing at least Bi, at least copper and alkaline earth (Group IIa) is formed on a substrate. , And an oxide containing at least copper and Ln.

Further, the superconducting thin film of the third invention comprises a layered oxide superconducting thin film having a main component of at least Bi, Cu and an alkaline earth (Group IIa) on a substrate, and a superconducting thin film having a main component of at least Bi, Cu,
It has a structure in which layered oxide insulator thin films composed of alkaline earth (IIa group) and Ln are alternately laminated.

Further, in the method for producing a superconducting thin film according to the fourth invention, the superconducting thin film is formed by periodically laminating an oxide containing at least Bi and an oxide containing at least Cu and an alkaline earth (Group IIa) on a substrate. An oxide thin film and an oxide thin film formed by periodically stacking an oxide containing at least Bi and an oxide containing at least Cu and alkaline earth (IIa group) and Ln are alternately stacked. What you get.

Here, A is an alkaline earth, and at least one or two or more elements of Group IIa elements, and Ln represents at least one element of Y or elements in the lanthanum series.

(Operation) The insulator according to the first aspect of the present invention is an extremely thermally stable Bi
_It has a crystal structure covered by a ₂ O ₂ oxide film layer or a layer mainly composed of this, and has a formation temperature almost equal to that of an oxide superconductor. In addition, the crystallinity and properties of the insulator and the oxide superconductor according to the present invention do not deteriorate with each other even after a process such as a high-temperature heat treatment. Further, the crystal structure of the insulator according to the first invention is the same perovskite structure as that of the oxide superconductor, and particularly, since the lengths of the a and b axes are substantially equal, the oxide superconductor and the insulator have a stable structure. Continuous lamination is possible.

Further, in the second invention, in order to achieve the above structure, at least one oxide containing at least BI and at least one oxide containing copper and an alkaline earth (Group IIa) or Y and a lanthanum element are contained. By periodically laminating oxides and producing thin films by controlling at the molecular level, a Bi-based superconducting thin film and an insulating film can be laminated with good reproducibility, which is also necessary for Josephson device design. This enables stable formation of an interlayer insulating film having a thickness of several hundreds mm or less.

Further, in the third invention, the Bi-based superconducting thin film and the insulator according to the first invention, which have a crystal structure covered by a Bi ₂ O ₂ oxide film layer or a layer mainly composed of the same, are used. By adopting a structure in which thin films are alternately stacked, it becomes possible to stack the interdiffusion of elements between the superconducting thin film and the insulating film, and as a result, the superconducting transition temperature of the Bi-based superconducting thin film is reduced. It is realized stably and with good reproducibility.

Further, in the fourth invention, an oxide containing at least Bi and an oxide containing at least copper and an alkaline earth (Group IIa) in order to achieve the structure of the third invention extremely stably and on a fine scale. Alternatively, a Bi-based superconducting thin film can be produced with good reproducibility by periodically stacking at least copper and an alkaline earth (IIa group) and an oxide containing Ln to form a thin film by controlling the molecular level. This realizes lamination with an insulating film.

(Example) Usually, Bi-Sr-Ca-Cu-O based oxide superconducting thin film is
Obtained by vapor deposition on a substrate heated to 600 to 700 ° C. After deposition,
Although the thin film shows superconducting properties as it is,
Heat treatment up to 950 ° C to improve superconductivity.

However, when the insulating film is laminated next to the oxide superconducting thin film when the substrate temperature is high, or when heat treatment is performed after forming the insulating film, mutual diffusion of elements between the superconducting film and the insulating film may occur. It has been found that the superconductivity is greatly deteriorated. In order to prevent mutual diffusion, the superconducting film and the insulating film must have excellent crystallinity, the lattice matching between the superconducting film and the insulating film must be excellent, and the insulating film must be at 700 to 950 ° C. It is considered essential to be stable to the heat treatment.

First, Bi-based superconductors with a structure sandwiched between Bi ₂ O ₂ oxide layers are extremely stable to high-temperature heat treatment,
It was investigated how the electrical properties of the superconductor change when each element constituting Bi-Sr-Ca-Cu-O is partially replaced by another element. As a result, Bi ₂ When a part of Ca was replaced with Ln in Sr ₂ Ca ₂ Cu ₂ O _x , the resistivity of the sample was found to increase at room temperature according to the amount of substitution. Here, Ln is an element belonging to Y and a lanthanum series.

In order to more clearly understand the first to fourth inventions, Examples 1 to 4 below are specifically described.

(Example 1) Here, an example of the invention when Ln = Nd is used for a bulk fired body will be described. First, Bi ₂ O ₃ , SrCO ₃ , CaCO ₃ , Nd ₂ O
_3. Mix the CuO oxide powder. Subsequently, in order to remove carbon molecules of this mixed powder, a heat treatment was performed at 700 ° C. for 5 hours in air. Further, the heat-treated mixed powder is pressed into a disk having a diameter of 8 mm and a thickness of 2 mm. This press was subjected to a heat treatment at 900 ° C. for 5 hours in an oxygen atmosphere. In order to produce a material of Bi ₂ Sr ₂ Ca _1-y Nd _y Cu ₂ O _x , Bi: Sr: Ca: Nd: Cu = 2: 2:
Weigh to 1-y: y: 2. Further, in order to measure electric characteristics, the platinum (Pt) electrode on the disk after the heat treatment is patterned and deposited by a high-frequency magnetron sputtering method. FIG. 1 shows the temperature characteristics of the resistivity of Bi ₂ Sr ₂ Ca _1-y Nd _y Cu ₂ O _x . It was found that as y was increased, the electrical characteristics became semiconductive, the superconductivity phenomenon disappeared when y ≧ 0.5, and that when y was 1, a complete insulator was obtained. However, making a perfect insulator narrows the range of application when making an electronic device. Further, as y approaches 1, the amount of strain in the crystal increases, so that y approaches 1. Is practically not a good idea, and it is preferable that y ≦ 0.75 be considered comprehensively. This Bi ₂ Sr ₂ LnCu ₂ O
The crystal structure of _x shown in FIG. 2 compared to that of _{Bi 2 Sr 2 Ca 2 Cu 2} O x.

Bi ₂ Sr ₂ Ca ₂ Cu ₂ O _x is composed of two pyramid-shaped Cu-Os, Sr-O,
It has a perovskite structure sandwiched between Bi ₂ O ₂ layers together with Ca—O (FIG. 2 (a)). On the other hand, Bi ₂ Sr ₂ LnCu ₂ O _x was analyzed from X-ray diffraction and the like to find that Ca of Bi ₂ Sr ₂ Ca ₂ Cu ₂ O _x was completely substituted with Ln (FIG. 2 (b)). ).

The reason why Bi ₂ Sr ₂ LnCu ₂ O _x exhibits much higher resistivity than Bi ₂ Sr ₂ Ca ₂ Cu ₂ O _x is not well understood at present, but is interpreted as follows. That is, electric conduction
Bi ₂ Sr _{2 with} Cu ²⁺ but with Ca ²⁺
In the case of CaCu ₂ O _x , holes are supplied to the Cu-O network.By replacing Ca ²⁺ with Ln ³⁺ having a different valence, the supply of holes is eliminated, and Bi ₂ Sr ₂ LnCu ₂ O _x becomes an insulator. It is possible. Furthermore, if the material of the Bi-Sr-Ln-Cu- O was described as _{Bi 2 Sr 3-y Ln y} Cu 2 O x, it was found that the electric conductivity appears when the y ≠ 1. When y <1, the crystal structure is the same as Bi ₂ Sr ₂ CaCu ₂ O _x ,
It is replaced by r and Ln. On the other hand, y> 1
In the case of Bi ₂ Sr ₂ Cu whose crystal structure has electrical conductivity
It was found that the change in O _2.

In Bi-Sr-Ln-Cu-O, the composition of Bi ₂ Sr ₂ LnCu ₂ O _x needs to be adjusted accurately in order to obtain insulating properties, but usually, a superconducting transition occurs. Is about 120 ゜ K
From the following, 0.5 in Bi ₂ Sr ₂ Ca _1-y Nd _y Cu ₂ O _x
If it is in the range of ≦ y ≦ 0.75, it will function as a suitable insulator.

The type of Ln that can be used as an insulator was examined. As a result, Ln = Ce, Y, Pr, Nd, Pm, Sm, Eu, Gd, Tb,
Bi ₂ Sr ₂ LnCu ₂ O _x was found to be an insulator for Dy, Ho, Tm, Yb, and Lu.

As a result of various studies, it was found that the above Bi ₂ Sr ₂ LnCu ₂ O _x was excellent as an insulator. For this reason, this material shows a layered perovskite in which a Bi ₂ O ₂ oxide layer sandwiches a structure composed of elements such as Sr, Ln, Cu and oxygen, and this Bi ₂ O ₂ layer is a substance having the same kind of crystal structure. Is very stable to high temperature heat treatment with respect to the interface, and since the lengths of the a-axis and b-axis in the crystal with a series of oxide superconductors are almost equal, the lattice matching is extremely excellent. When this material is thinned, it is deposited on the oxide superconductor.
It is mentioned that continuous epitaxial growth of oxide superconductor on Bi ₂ Sr ₂ LnCu ₂ O _x and further on Bi ₂ Sr ₂ LnCu ₂ O _x is possible. Therefore, Bi ₂ Sr ₂ LnCu ₂ O _x was attempted to be thinned, and a high-frequency magnetron sputtering method was used for the thinning. 850 in air as a sputtering target
Bi ₂ Sr ₂ was obtained by performing sputtering in a mixed gas atmosphere of Ar and O ₂ using a mixed oxide fired at 5 ° C. for 5 hours.
It has been found that LnCu ₂ O _x can be made thinner. However, when the oxide high-temperature superconductor is applied to an electronic device, the thickness of the insulating film is required to be about several hundreds of mm, and the crystal structure of the insulator is shown in FIG. 2 (b). It has a similar structure, and the crystals are Bi-O, Sr-Cr-O, Ln-Cu-O
Since each part is sequentially laminated, the second
Invention.

 An embodiment of the second invention is shown in the following embodiment 2.

Embodiment 2 FIG. 3 shows a schematic diagram of a ternary magnetron sputtering apparatus used in this embodiment. In FIG. 3, reference numeral 11 denotes a Bi target, 12 denotes an SrCu alloy target, 13 denotes an NdCu alloy target, 14 denotes a shutter, 15 denotes a slit, 16 denotes a substrate, and 17 denotes a substrate heating heater. Three targets 11, 12, 13
Are arranged as shown in FIG. That is, MgO (10
0) Each target is installed at an angle of about 30 ° so as to focus on the base 17. A rotating shutter 14 is provided in front of the target, and when driven by a pulse motor, the rotation of a slit 15 provided therein is controlled, so that the cycle and sputtering time of each target can be set. The target 16 was heated to about 600 ° C. by the heater 17 of the base 16, and each target was sputtered in a gas of a mixed atmosphere of argon and oxygen (5: 1) 3 Pa. The experiment was performed with the sputtering current of each target set to Bi: 30 mA, SrCu: 80 mA, and NdCu: 300 mA. Sputtering in the cycle of Bi → SrCu → NdCu → Bi, the composition ratio of the elements of the Bi-Sr-Nd-Cu-O film is Bi: Sr: N
The sputtering time of each target was adjusted so that d: Cu = 2: 2: 1: 2, and the above cycle was performed for 7 cycles. Even in this state, the Bi-Sr-Nd-Cu-O thin film becomes a c-axis oriented film, and a stable insulating film can be formed. A film with good crystallinity was obtained.

It should be noted that a Bi-Sr-Nd-Cu-O insulating film thin film can be obtained by a vapor deposition method using a single evaporation source. Therefore, the method of the second invention is effective.

Further, effective lamination of an insulating thin film and a superconducting thin film was attempted, and the third invention was achieved.

A specific example of the third invention is shown below as Example 3.

Example 3 FIG. 4 schematically shows a cross-sectional view of a thin film produced by the present invention. In FIG. 4, a Bi—Sr—Ca—Cu—O film was formed on a substrate.
Bi-Sr-Nd-Cu-O films were alternately laminated. As a lamination method, a Bi-Sr-Ca-Cu-O film is deposited by a single target high-frequency magnetron sputtering method, and a Bi-Sr-Nd-Cu-O film is further deposited by the method described in Example 2. did. Bi-Sr
-The thickness of the Ca-Cu-O film is about 1000Å, and Bi-Sr-Nd-
The thickness of the Cu—O film, that is, the number of lamination cycles in the experimental apparatus of FIG. 3 used in Example 2 was changed to examine the change in the resistivity of the thin film. The results are shown in FIG. Here, the number of cycles is m
And When m = 6, the highest superconducting transition temperature and zero resistance temperature, that is, characteristic 32, are obtained. The superconducting transition temperature and zero resistance temperature of characteristic 32 were about 8 K higher than those of the Bi-Sr-Ca-Cu-O film. Although the detailed reason for this result is still unknown, as shown in FIG. 4, the Bi—Sr—Ca—Cu—O film and the Bi—Sr—Nd—Cu
-O film is periodically laminated to form Bi-Sr-Ca
-Cu-O film and the Bi-Sr-Nd-Cu- O film without elemental influence of interdiffusion at the interface between the stacked layers by the epitaxially grown via a Bi ₂ O ₂ layer to each other, and excellent crystallinity By stacking a Bi-Sr-Ca-Cu-O film also having excellent crystallinity via a thin Bi-Sr-Nd-Cu-O film, Bi-Sr-
It is possible that some change in the superconducting mechanism was caused in the Ca-Cu-O film, but the mechanism cannot be clarified yet.

Note that the effect of increasing the superconducting transition temperature is Bi → SrCu →
The present inventors have confirmed that the cycle of NdCu → Bi is particularly effective in the range of 4 to 10.

Note that, instead of the Bi-Sr-Nd-Cu-O film, Bi-Sr-Ln
-Cu-O (Ln = Ce, Y, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Tm, Y
It was confirmed that the third invention was also effective when a (b, Lu) film was used. Also, when Bi: Sr: Ln: Cu = 2: 2: 1: 2, the superconductor having the highest insulating property and the composition of the third invention using the composition has the most improved superconductivity and stability. showed that.

 Embodiment 4 Embodiment 4 of the present invention will be described below.

(Example 4) FIG. 6 is a schematic view of the inside of a quaternary magnetron sputtering apparatus used in this example, where 41 is a Bi target and 42 is Sr.
A Cu target, 43 is a CaCu target, 44 is an NdCu target, 45 is a shutter, 46 is a slit, 47 is a substrate, and 48 is a substrate heating heater. The target 41 is a metal target, and the targets 42, 43, and 44 are element ratios Sr (or Ca,
Or Nd): Cu = 1: 1 alloy target, which was arranged as shown in FIG. That is, the MgO (100) substrate 47
Each target is installed at an angle of about 30 ° to focus on the target. A rotating shutter 45 in front of the target
By controlling the rotation of the slit 46 provided therein with a pulse motor, (Bi → SrCu → NdCu → Sr
Sputter deposition can be performed in a cycle of (Cu → Bi) and a cycle of (Bi → SrCu → CaCu → SrCu → Bi). FIG. 7 conceptually shows the state of lamination, and the targets 41, 42, 43, 4
By controlling the input power to 4 and the sputtering time of each target, Bi-Sr-Nd
-The thickness of the Cu-O film and the Bi-Sr-Ca-Cu-O film can be changed. The substrate 47 was heated to about 700 ° C. by a heater 48, and each target was sputtered in a gas of 0.5 Pa in a mixed atmosphere of argon and oxygen (1: 1). After forming the thin film, a heat treatment at 850 ° C. was performed for 5 hours in an oxygen atmosphere.

In this embodiment, the composition ratio of the elements of the Bi-Sr-Ca-Cu-O film is Bi: Sr: Ca: Cu = 2: 2: 2: 3, and the element ratio of the Bi-Sr-Nd-Cu-O film. The sputtering current was adjusted so that the composition ratio became Bi: Sr: Nd: Cu = 2: 2: 1: 2. Further, it is considered that the limit of the film thickness that can be reduced while maintaining the crystallinity is several tens of mm. Since the insulating film is preferably as thin as possible,
・ (Bi → SrCu → CaCu → SrCu → Bi) → l ・ (Bi → SrCu → Nd
The cycle that can be expressed as Cu → SrCu → Bi) was performed 20 times. Note that Bi-Sr-Nd can be manufactured while maintaining a favorable crystal structure.
The film thickness of the -Cu-O film was limited to l = 2. Then, l
When = 2, the temperature change of the resistivity of the thin film completed by changing ΔK was examined, and the result at that time is shown in FIG. In FIG. 8, 81 is ΔK = 2, 82 is ΔK = 6, 83 is ΔK = 1.
The result at the time of 0 is shown. As can be seen from this figure, ゜ K =
6, it was found that the superconducting transition temperature and the zero resistance temperature rose most as compared with the case where the insulating film was not laminated with Bi-Sr-Nd-Cu-O. Although the physical cause of this is not well understood, according to the fourth invention, the Bi-Sr-Ca-Cu-O thin film and the Bi-
It is considered that both of the Sr-Nd-Cu-O thin films could be laminated with extremely controllability.

Further, the Bi oxide and the Sr, Ca, Cu, Nd oxides are separately evaporated from different evaporation sources in vacuum without using the sputtering method in the second and fourth inventions, and the same structure is obtained. When the layers are periodically stacked, it is possible to obtain a thin film of stable film quality with the same controllability as in the method of manufacturing a stacked structure by using the sputtering shown in (Example 4). Bi
There are several possible methods for periodically stacking -O, Sr-Cu-O, Ca-Cu-O, and Nd-O. In general, periodic lamination is achieved by controlling the front of the evaporation source with an opening / closing shutter using an MBE device or a multi-source EB evaporation device, or by switching the type of gas when manufacturing by vapor phase growth. be able to. However, sputtering deposition has heretofore been unsuitable for stacking very thin layers of this type. It is considered that the reason for this is that impurities are mixed due to the high gas pressure during the film formation and damage is caused by high energy particles. However, when different thin layers were formed by sputtering on the Bi-based oxide superconductor and the insulating thin film, it was found that a surprisingly good laminated film could be produced. Due to the high oxygen gas pressure and sputtering discharge during sputtering, the introduction of oxygen into the film is further promoted, and the reproducibility and stabilization of the superconducting characteristics are achieved.
This is probably because it is convenient for forming a phase having a critical temperature of 0 ° K or more and for forming an insulating thin film.

As a method of laminating different materials by sputter deposition, there is a method of periodically controlling the discharge position of one sputtering target having a composition distribution, but a method of sputtering a plurality of targets having different compositions is used. And can be achieved relatively easily. In this case, a periodic laminated film can be manufactured by periodically controlling the amount of sputtering of each of the plurality of targets, or by providing a shutter in front of the targets and periodically opening and closing them. Further, it can also be manufactured by a method in which the substrate is moved periodically over the target by periodically moving the substrate.
In the case of using laser sputtering or ion beam sputtering, a periodic laminated film can be realized by periodically moving a plurality of targets to change the target to be irradiated with a beam periodically. Thus, the periodic lamination of the Bi-based oxide can be relatively easily produced by sputtering using a plurality of targets. As shown in (Examples 2 and 4), Bi-O, Sr-Cu-O, Ca-Cu-O, and Nd-O were evaporated from separate evaporation sources, and Bi-Sr-Ca-Cu-O Conductive thin film and Bi-Sr
-N (Bi-Sr-Ca-Cu-O) .n (Bi-Sr-Nd-O) with very controllability when -Nd-O insulating film is periodically laminated
It has been found that a thin film having a periodic structure can be formed.
Here, m and n indicate positive integers. In addition, Bi
Even if a composite oxide of -Sr-Ca-Cu-O or Bi-Sr-Nd-O is used, a thin film can be formed by a simple method. When separate evaporation sources are used, a production method with more excellent crystallinity and excellent composition controllability can be obtained. It has also been found that it has superior properties such as superconducting transition temperature and critical current density. further,
Bi-Sr-Ca-Cu-O superconducting thin film produced by the above method and
The Bi-Sr-Nd-Cu-O insulating film was found to have an extremely flat thin film surface. This is because, by sequentially and sequentially laminating the different elements constituting the layered structure separately, the deposited elements only move in a plane parallel to the substrate surface, and the vapor deposition elements move in a direction perpendicular to the substrate surface. It is considered that there is no element movement. Furthermore, the insulating thin film of this composition is a crystal having a layered perovskite structure, and the length of the a-axis is almost equal to that of Bi-Sr-Ca-Cu-O, which is considered to be due to the fact that continuous epitaxial growth is possible. Can be

In addition, the present inventors have also found that the temperature of the substrate and the heat treatment temperature necessary for obtaining good superconducting properties are lower than before.

(Effect of the Invention) As described above, the insulator of the first invention provides an element part indispensable for the device configuration of the oxide superconducting thin film, and the method of manufacturing the insulating thin film of the second invention is as follows. The first invention has been more effectively realized, and a low-temperature process essential for application of devices and the like has been established. The superconducting thin film of the third invention is intended to improve the performance of oxide superconducting thin films. The method for manufacturing a superconducting thin film according to the fourth aspect of the present invention realizes the third aspect of the invention more effectively, and establishes a low-temperature process essential for application of devices and the like. The industrial value of the present invention is great.

[Brief description of the drawings]

FIG. 1 is a temperature characteristic diagram of the resistivity of an insulator according to the embodiment of the first invention, FIG. 2 is a conceptual diagram of the structure according to the embodiment of the first invention, and FIG. FIG. 4 is a schematic view of an apparatus used for the method of manufacturing an insulating thin film, FIG. 4 is a cross-sectional view of the thin film manufactured according to the third invention, and FIG. 5 shows the temperature dependence of the resistance of the superconducting thin film in the third embodiment. FIG. 6, FIG. 6 is a schematic view of an apparatus used for the method of manufacturing a superconducting thin film in the embodiment of the fourth invention, FIG. 7 is a conceptual diagram of the structure of the thin film production of the fourth invention, and FIG. FIG. 4 is a temperature characteristic diagram of resistivity of a thin film obtained in an example of the invention. 11,12,13,41,42,43,44 …… sputtering target,
14,45 …… Shutter, 15,46 …… Slit, 17,47 …… M
gO base, 17,48… heater, 31, 32, 33, 81, 82, 83… temperature characteristics of thin film resistance.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification symbol FI H01L 39/24 ZAA H01L 39/24 ZAAB (72) Inventor Hideaki Adachi 1006 Odakadoma, Kadoma-shi, Osaka Matsushita Electric Industrial Co., Ltd. (72) Inventor Kentaro Seto 1006 Kazuma Kadoma, Kadoma, Osaka Prefecture Inside Matsushita Electric Industrial Co., Ltd. (56) References JP-A-3-50122 (JP, A)

Claims (13)

(57) [Claims] (1) The main component is at least bismuth (Bi), copper (Cu), calcium (Ca), alkaline earth (Group IIa),
And Y and at least one element in the lanthanum series, and the ratio of the elements is Bi: A: Ca: Ln: Cu = 2: 2: 1−y: y: 2 (0.5 ≦ y ≦ 0.75) An insulator (here, A is an alkaline earth, and represents at least one or two or more elements of Group IIa elements; Ln is at least one of Y or elements in the lanthanum series) Element). 2. The method according to claim 1, wherein an oxide containing at least Bi, an oxide containing at least copper and an alkaline earth (Group IIa), and an oxide containing at least copper and Ln are periodically laminated on a substrate. Characteristic method for producing an insulating thin film (where the alkaline earth is at least one or more of the Group IIa elements. Ln is at least one element of Y or a lanthanum series element) Shown). 3. The method according to claim 1, wherein the ratio of the elements constituting the main component is Bi: A: B: Ln: Cu = 2: 2: 1−y: y: 2 (0.5 ≦ y ≦ 0.75). Item (2): A method for producing an insulating thin film (where A and B are alkaline earths and IIa
It represents at least one element or two or more elements among group elements. Ln represents at least one element of Y or a lanthanide element). 4. The method for producing an insulating thin film according to claim 2, wherein the evaporation of the laminated material is performed by at least two or more types of evaporation sources. 5. The method according to claim 2, wherein the evaporation of the laminated material is performed by sputtering. 6. A layered oxide superconducting thin film whose main component is at least Bi, Cu and alkaline earth (Group IIa), and a main component is at least Bi, Cu and alkaline earth (IIa)
Group), a superconducting thin film having a structure in which layered oxide insulator thin films composed of Ln are alternately laminated (where the alkaline earth is at least one or more of the group IIa elements) Ln represents at least one element of Y or an element belonging to the lanthanum series). 7. The oxide insulating thin film, wherein the ratio of elements constituting a main component is Bi: A: B: Ln: Cu = 2: 2: 1−y: y: 2 (0.5 ≦ y ≦ 0.75) The superconducting thin film according to claim (6), wherein A and B are alkaline earths and represent at least one element or two or more elements of Group IIa elements.
Ln represents at least one element of Y or a lanthanide element). 8. The ratio of elements constituting the main component in one oxide thin film is Bi: A: B: Ln: Cu = 2: 2: 1−y: y: 2 (0.5 ≦ y ≦ 0.75). The superconducting thin film according to claim 6, wherein A and B are alkaline earths and represent at least one element or two or more elements of Group IIa elements. Ln
Represents at least one element of Y or a lanthanide series element). 9. The superconducting thin film according to claim 6, wherein the evaporation of the laminated material is performed by at least two or more evaporation sources. 10. The superconducting thin film according to claim 6, wherein the evaporation of the laminated material is performed by sputtering. 11. An oxide thin film formed by periodically stacking an oxide containing at least Bi and an oxide containing at least Cu and an alkaline earth (Group IIa) on a substrate;
An oxide thin film formed by periodically stacking an oxide containing at least Bi and an oxide containing at least Cu and alkaline earth (IIa group) and Ln is obtained by alternately stacking. (Where the alkaline earth is at least one or more of the Group IIa elements. Ln is at least one of the elements in the Y or lanthanum series) ). 12. The method for producing a superconducting thin film according to claim 11, wherein the evaporation of the laminated material is performed by at least two or more evaporation sources. 13. The method for producing a superconducting thin film according to claim 11, wherein the evaporation of the laminated material is performed by sputtering.