JPH03285373A - Manufacture of josephson junction - Google Patents
Manufacture of josephson junctionInfo
- Publication number
- JPH03285373A JPH03285373A JP2086951A JP8695190A JPH03285373A JP H03285373 A JPH03285373 A JP H03285373A JP 2086951 A JP2086951 A JP 2086951A JP 8695190 A JP8695190 A JP 8695190A JP H03285373 A JPH03285373 A JP H03285373A
- Authority
- JP
- Japan
- Prior art keywords
- thin film
- bulk
- film
- mgo
- superconducting
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
- 238000004519 manufacturing process Methods 0.000 title claims description 7
- 239000010409 thin film Substances 0.000 claims abstract description 29
- 239000013078 crystal Substances 0.000 claims abstract description 28
- 239000002887 superconductor Substances 0.000 claims abstract description 9
- 238000000034 method Methods 0.000 claims abstract description 5
- 239000012212 insulator Substances 0.000 claims 1
- 239000010408 film Substances 0.000 abstract description 13
- MCMNRKCIXSYSNV-UHFFFAOYSA-N Zirconium dioxide Chemical compound O=[Zr]=O MCMNRKCIXSYSNV-UHFFFAOYSA-N 0.000 abstract description 4
- 230000007547 defect Effects 0.000 abstract description 4
- 239000000758 substrate Substances 0.000 abstract description 4
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 abstract description 2
- 229910052593 corundum Inorganic materials 0.000 abstract description 2
- CPLXHLVBOLITMK-UHFFFAOYSA-N magnesium oxide Inorganic materials [Mg]=O CPLXHLVBOLITMK-UHFFFAOYSA-N 0.000 abstract description 2
- 229910001845 yogo sapphire Inorganic materials 0.000 abstract description 2
- 238000001659 ion-beam spectroscopy Methods 0.000 abstract 1
- 238000002441 X-ray diffraction Methods 0.000 description 4
- 230000015572 biosynthetic process Effects 0.000 description 3
- 238000010438 heat treatment Methods 0.000 description 2
- 150000002500 ions Chemical class 0.000 description 2
- 238000004544 sputter deposition Methods 0.000 description 2
- 230000004888 barrier function Effects 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 238000007716 flux method Methods 0.000 description 1
- 238000009413 insulation Methods 0.000 description 1
- 239000002245 particle Substances 0.000 description 1
- 238000010583 slow cooling Methods 0.000 description 1
- 239000002689 soil Substances 0.000 description 1
- 239000007858 starting material Substances 0.000 description 1
- LEDMRZGFZIAGGB-UHFFFAOYSA-L strontium carbonate Chemical compound [Sr+2].[O-]C([O-])=O LEDMRZGFZIAGGB-UHFFFAOYSA-L 0.000 description 1
- 229910000018 strontium carbonate Inorganic materials 0.000 description 1
Abstract
Description
【発明の詳細な説明】
〔産業上の利用分野〕
本発明は、高温酸化物超電導体を用いたトランジスタ等
のジョセフソン接合作製方法に関する。DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for manufacturing a Josephson junction of a transistor or the like using a high-temperature oxide superconductor.
従来より、高温酸化物超電導体を利用する積層型ジョセ
フソン接合は、ＭｇＯ等の絶縁性基板上に例えばＹＢａ
ｚＣｕ＋Ｏｘ超電導薄膜を形成し、この上にＭｇＯ，Ａ
ｌ２Ｏ３等の絶縁性薄膜全形成すると共に、さらにこの
上にＹＢａ２Ｃｕ３０）（超電導薄膜を形成し、いわゆ
る５１５構造にすることにより作製されている。Conventionally, stacked Josephson junctions using high-temperature oxide superconductors have been made using YBa, for example, on an insulating substrate such as MgO.
zCu+Ox superconducting thin film is formed, and MgO, A
It is fabricated by completely forming an insulating thin film such as l2O3, and further forming a YBa2Cu30 (superconducting thin film) on top of this to form a so-called 515 structure.
しかし、前述したような薄膜による積層構造の場合、超
電導薄膜は酸化物であることからこれ全平坦に形成する
ことが困難であり、また、トンネルバリアである絶縁性
薄膜は酸化物超電導体のコヒーレンス長（数１０人）ま
でに薄くしなければならず、しかもこれを平坦化が困難
な酸化物超電導薄膜上に形成することから−様な膜厚に
ならず、ピンホール等の欠陥のない絶縁性薄膜全薄く超
電導薄膜上に形成することが困難となり、再現性良くジ
ョセフソン接合を得ることができない欠点がある。However, in the case of the laminated structure of thin films as described above, since the superconducting thin film is an oxide, it is difficult to form it completely flat, and the insulating thin film that serves as the tunnel barrier is difficult to form due to the coherence of the oxide superconductor. It must be made as thin as possible (several tens of nanometers), and because it is formed on an oxide superconducting thin film that is difficult to planarize, it is possible to achieve an insulation that is free from defects such as pinholes and does not have an unusually thick film. However, it is difficult to form a completely thin superconducting thin film on a superconducting thin film, and a Josephson junction cannot be obtained with good reproducibility.
本発明は、従来の技術の有するこのような問題点に留意
してなされたものであり、その目的とするところは、再
現性良く積層型ジョセフソン接合を形成できる作製方法
を提供することにある。The present invention has been made with these problems of the prior art in mind, and its purpose is to provide a manufacturing method that can form a stacked Josephson junction with good reproducibility. .
前記目的を達成するために、本発明のジョセフソン接合
作製方法においては、単結晶超電導バルクの表面にこの
表面の結晶方位と近似した結晶方位の単結晶絶縁薄膜全
形成し、この絶縁薄膜の表面に超電導薄膜を形成するよ
うにしたことを特徴としている。In order to achieve the above object, in the Josephson junction fabrication method of the present invention, a single crystal insulating thin film with a crystal orientation similar to that of this surface is entirely formed on the surface of a single crystal superconducting bulk, and the surface of this insulating thin film is It is characterized by the fact that a superconducting thin film is formed on the surface.
単結晶超電導バルクの表面に形成された単結晶絶縁薄膜
はバルク表面の結晶方位と近似した結晶方位？有してい
るため、両者の格子定数のミスマツチが小さく、ピンホ
ール等の欠陥のない単結晶絶縁膜が超電導バルクの表面
に薄く形成され、この上に超電導薄膜全形成することに
より、再現性良く積層型のジョセフソン接合が得られる
。Does the single-crystal insulating thin film formed on the surface of a single-crystal superconducting bulk have a crystal orientation similar to that of the bulk surface? As a result, the mismatch in the lattice constants between the two is small, and a single crystal insulating film without defects such as pinholes is formed thinly on the surface of the superconducting bulk, and by forming the entire superconducting thin film on top of this, it is possible to achieve high reproducibility. A stacked Josephson junction is obtained.
実施例につき図面を用いて説明する。 Examples will be explained using drawings.
第１図はジョセフソン接合の分解斜視図であり、まず、
Ｃ軸配向のＢ】系単結晶超電導バルク（１）ヲ、例エバ
、出発原料トＬ テＢ１２Ｏ３、ＳｒＣＯ３，ＣａＣＯ
３，ＣｕＯを用い、これらを所定比（Ｂｉ２５ｒ２Ｃａ
Ｃｕ２０ｘ）に混合した後、自己フラックス法により作
製する。Figure 1 is an exploded perspective view of a Josephson junction.
C-axis oriented B] system single crystal superconducting bulk (1), e.g. Eva, starting material L Te B12O3, SrCO3, CaCO
3. Using CuO, these were mixed in a predetermined ratio (Bi25r2Ca
After mixing with Cu20x), it is produced by a self-flux method.
その際の熱処理工程は、９５０℃〜１０００℃の温度全
１０〜３０時間保持し、その後、３５〜７０時間かけて
７５０℃〜８００°Ｃの温度まで下げ、さらに徐冷を行
う。In the heat treatment step, the temperature is maintained at 950° C. to 1000° C. for a total of 10 to 30 hours, and then the temperature is lowered to 750° C. to 800° C. over 35 to 70 hours, followed by slow cooling.
このようにして得られたＢｉ２５ｒ２ＣａＣｕ２０ｘの
単結晶は、０．５Ｘ Ｏ，５ｘ Ｏ，０１麿３程度であ
り、その単結晶のＸ線回折ピークは第２図に示すように
なり、Ｃ軸配向の単結晶が得られていることがわかる。The single crystal of Bi25r2CaCu20x obtained in this way has a particle size of about 0.5X O,5x O,013, and the X-ray diffraction peak of the single crystal is as shown in Figure 2, indicating that the C-axis orientation is It can be seen that a single crystal was obtained.
この単結晶は、臨界温度Ｔｃｅ ＝８１Ｋ ｋもつ超電
導体である。This single crystal is a superconductor with a critical temperature Tce =81K k.
次に、前記単結晶超電導バルクｎ＋ １基板として用い
、この表面にＭｇＯ，ＺｒＯ２，Ａｌ２Ｏ３等からなる
単結晶絶縁薄膜（２）を例えば数１０人の膜厚に形成す
る。Next, using the single crystal superconducting bulk n+1 substrate, a single crystal insulating thin film (2) made of MgO, ZrO2, Al2O3, etc. is formed on the surface to a thickness of, for example, several tens of layers.
この絶縁薄膜（２）としてＭｇＯｆ用いた場合の成膜条
件は、ターゲットとして直径４インチのＭｇＯｆｅｚ用
い、チャンバ内の初期圧力ｆ ＩＱ ’Ｐａ以下、イオ
ンガンの出力ｋ １２０ｍＡ、ｉｋ〜′、バイアス電圧
ヲ１５０■、スパッタ時のチャンバ内圧力１１ＱＰａ以
下、成膜速度ｆ ０．Ｏ３ｎｍ／ｓｅｅとした。When MgOf is used as the insulating thin film (2), the film formation conditions are as follows: MgOfez with a diameter of 4 inches is used as a target, the initial pressure in the chamber is below f IQ 'Pa, the output of the ion gun is k 120 mA, ik~', and the bias voltage is 150■, chamber internal pressure during sputtering 11QPa or less, film formation rate f 0. It was set to O3nm/see.
その後、バルク（］）土に形成した絶縁薄膜ｆ２１’ｔ
７３５〜７４５℃の間で熱処理全行い、Ｘ線回折した
ところ、第３図に示すように、ＭｇＯではその（１１１
）面のピークのみが見られ、バルク（１）上に（１１１
）方向の単結晶ＭｇＯが形成されていることがわかり、
ＳＥＭ（走査電子顕微鏡）等の微構造観察からも平坦性
の良好な膜であることを確認している。After that, an insulating thin film f21't was formed on the bulk (]) soil.
All heat treatment was carried out between 735 and 745°C, and X-ray diffraction was performed. As shown in Figure 3, MgO has a
) plane peak is seen, and (111
) It was found that single crystal MgO was formed in the direction.
It has been confirmed that the film has good flatness from microstructural observation using SEM (scanning electron microscope) and the like.
これらのことは、第１図に示したように、Ｍｇ０（１１
１）の格子定数（５，８人）とＢｉｚＳｒ２ＣａＣｕｚ
Ｏｘ（ＯＯｌり ｔＤ格子定数（５，４Ａ）とのマツチ
ングの良さ（ミスマツチ７％）によるものである。As shown in Figure 1, these things are true for Mg0(11
1) Lattice constant (5, 8 people) and BizSr2CaCuz
This is due to the good matching (7% mismatch) with Ox (OOl) tD lattice constant (5,4A).
次に、ジョセフソン接合を形成するために、バルク（１
）上の絶縁薄膜（２，、の表面に、イオンビームスパッ
タリング法により、Ｂｉ２５ｒ２ＣａＣｕ２０ｘ（００
ｒ）よりなる超電導薄膜ｉａｉを２０００〜３０００Ｘ
の膜厚に形成する。Next, to form a Josephson junction, the bulk (1
) Bi25r2CaCu20x (00
r) Superconducting thin film iai consisting of 2000-3000X
Formed to a film thickness of .
この場合の成膜条件は、ターゲットとして直径４ イン
％ ノＢｉｚＳｒｚＣｕ２０ｘ ｆ用い、初期圧力１０
−’Ｐａ以下、イオンガン出力１２０ｍＡ 、 １ ｋ
Ｖ 、バイアス電圧１５０■、スパッタ時圧力１ｏ−２
ｐａ以下、成膜速度０．０４１ｍ／ｓ＋！ｃであり、さ
らに、基板温度’ｉ ６００−６５０°Ｃと上げた状態
で０２アシストを行うことにより、ＢｌｚＳｒｚＣａＣ
ｕ ２０Ｘの超電導薄膜（３）全形成することができる
。In this case, the film forming conditions were as follows: BizSrzCu20x f with a diameter of 4 in% was used as the target, and an initial pressure of 10
-'Pa or less, ion gun output 120mA, 1k
V, bias voltage 150■, sputtering pressure 1o-2
Pa or less, film formation speed 0.041 m/s+! By performing 02 assist with the substrate temperature 'i raised to 600-650°C, BlzSrzCaC
A superconducting thin film (3) of u 20X can be completely formed.
このようにして、第１図に示すジョセフソン接合が作製
できる。In this way, the Josephson junction shown in FIG. 1 can be manufactured.
本発明は、以上説明したように構成されているため、次
に記載する効果を奏する。Since the present invention is configured as described above, it produces the effects described below.
単結晶超電導バルクにこの表面の結晶方位と近似した結
晶方位の単結晶絶縁薄膜を形成するようにしたので、超
電導体上に格子定数のミスマツチが小さく、ピンホール
等の欠陥のない単結晶絶縁膜を薄くかつ平坦に形成する
ことができ、再現性良くジョセフソン接合を形成できる
ものである。By forming a single-crystal insulating thin film with a crystal orientation similar to the surface crystal orientation on the single-crystal superconductor bulk, we can create a single-crystal insulating film with small lattice constant mismatches and no defects such as pinholes on the superconductor. can be formed thin and flat, and Josephson junctions can be formed with good reproducibility.
図面は本発明によるンヨセフソン接合作製方法の１実施
例を示し、第１図は分解斜視図、第２図は単結晶超電導
バルクのＸ線回折パターン図、第３図はバルク上に単結
晶絶縁薄膜全形成した場合のＸ線回折パターン図である
。
ｊｌｌ・−・単結晶超電導バルク、
（２）
単結晶絶縁薄膜、
３）・
超電導薄膜。The drawings show one embodiment of the method for manufacturing a Nyosefson junction according to the present invention, in which Fig. 1 is an exploded perspective view, Fig. 2 is an X-ray diffraction pattern of a single-crystal superconducting bulk, and Fig. 3 is a single-crystal insulating thin film on the bulk. It is an X-ray diffraction pattern diagram when completely formed. jll -- Single crystal superconducting bulk, (2) Single crystal insulating thin film, 3) Superconducting thin film.
Claims (1)
ン接合作製方法において、 単結晶超電導バルクの表面に該バルクの表面の結晶方位
と近似した結晶方位の単結晶絶縁薄膜を形成する工程と
、 前記絶縁薄膜の表面に超電導薄膜を形成する工程と、 よりなるジョセフソン接合作製方法。(1) A method for producing a stacked Josephson junction of superconductor/insulator/superconductor, which includes the step of forming a single-crystal insulating thin film on the surface of a single-crystal superconducting bulk with a crystal orientation similar to that of the surface of the bulk; A method for manufacturing a Josephson junction, comprising: forming a superconducting thin film on the surface of the insulating thin film.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2086951A JPH03285373A (en) | 1990-03-31 | 1990-03-31 | Manufacture of josephson junction |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2086951A JPH03285373A (en) | 1990-03-31 | 1990-03-31 | Manufacture of josephson junction |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH03285373A true JPH03285373A (en) | 1991-12-16 |
Family
ID=13901181
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP2086951A Pending JPH03285373A (en) | 1990-03-31 | 1990-03-31 | Manufacture of josephson junction |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH03285373A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5565415A (en) * | 1991-01-10 | 1996-10-15 | Sumitomo Electric Industries, Ltd. | Method for manufacturing tunnel junction type josephson device composed of compound oxide superconductor material |
-
1990
- 1990-03-31 JP JP2086951A patent/JPH03285373A/en active Pending
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5565415A (en) * | 1991-01-10 | 1996-10-15 | Sumitomo Electric Industries, Ltd. | Method for manufacturing tunnel junction type josephson device composed of compound oxide superconductor material |
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