JPH10233535A - Josephson element and its manufacture - Google Patents
Josephson element and its manufactureInfo
- Publication number
- JPH10233535A JPH10233535A JP9050931A JP5093197A JPH10233535A JP H10233535 A JPH10233535 A JP H10233535A JP 9050931 A JP9050931 A JP 9050931A JP 5093197 A JP5093197 A JP 5093197A JP H10233535 A JPH10233535 A JP H10233535A
- Authority
- JP
- Japan
- Prior art keywords
- substrate
- josephson
- present
- quality
- josephson element
- Prior art date
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Links
- 238000004519 manufacturing process Methods 0.000 title claims description 9
- 239000000758 substrate Substances 0.000 claims abstract description 49
- 238000000034 method Methods 0.000 claims abstract description 19
- 239000010409 thin film Substances 0.000 claims description 20
- 239000013078 crystal Substances 0.000 abstract description 21
- 238000001000 micrograph Methods 0.000 abstract description 8
- 241000238366 Cephalopoda Species 0.000 description 15
- 230000000052 comparative effect Effects 0.000 description 6
- 230000007423 decrease Effects 0.000 description 6
- 230000004907 flux Effects 0.000 description 6
- 230000005668 Josephson effect Effects 0.000 description 5
- 239000000463 material Substances 0.000 description 5
- 230000001747 exhibiting effect Effects 0.000 description 4
- OKKJLVBELUTLKV-UHFFFAOYSA-N Methanol Chemical compound OC OKKJLVBELUTLKV-UHFFFAOYSA-N 0.000 description 3
- 238000000206 photolithography Methods 0.000 description 3
- CSCPPACGZOOCGX-UHFFFAOYSA-N Acetone Chemical compound CC(C)=O CSCPPACGZOOCGX-UHFFFAOYSA-N 0.000 description 2
- 229910002367 SrTiO Inorganic materials 0.000 description 2
- 238000010438 heat treatment Methods 0.000 description 2
- 238000005304 joining Methods 0.000 description 2
- 230000003287 optical effect Effects 0.000 description 2
- 229920002120 photoresistant polymer Polymers 0.000 description 2
- 239000002887 superconductor Substances 0.000 description 2
- 229910052727 yttrium Inorganic materials 0.000 description 2
- 229910052788 barium Inorganic materials 0.000 description 1
- 238000005229 chemical vapour deposition Methods 0.000 description 1
- 238000004140 cleaning Methods 0.000 description 1
- 229910052802 copper Inorganic materials 0.000 description 1
- 230000006866 deterioration Effects 0.000 description 1
- SWXVUIWOUIDPGS-UHFFFAOYSA-N diacetone alcohol Natural products CC(=O)CC(C)(C)O SWXVUIWOUIDPGS-UHFFFAOYSA-N 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000001312 dry etching Methods 0.000 description 1
- 238000005530 etching Methods 0.000 description 1
- PCHJSUWPFVWCPO-UHFFFAOYSA-N gold Chemical compound [Au] PCHJSUWPFVWCPO-UHFFFAOYSA-N 0.000 description 1
- 229910052737 gold Inorganic materials 0.000 description 1
- 239000010931 gold Substances 0.000 description 1
- 238000000608 laser ablation Methods 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 239000003550 marker Substances 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 238000001451 molecular beam epitaxy Methods 0.000 description 1
- 230000000737 periodic effect Effects 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
- 229910052709 silver Inorganic materials 0.000 description 1
- 239000004332 silver Substances 0.000 description 1
- 238000004544 sputter deposition Methods 0.000 description 1
- 229910002076 stabilized zirconia Inorganic materials 0.000 description 1
- 238000004506 ultrasonic cleaning Methods 0.000 description 1
- VWQVUPCCIRVNHF-UHFFFAOYSA-N yttrium atom Chemical compound [Y] VWQVUPCCIRVNHF-UHFFFAOYSA-N 0.000 description 1
Landscapes
- Superconductor Devices And Manufacturing Methods Thereof (AREA)
Abstract
Description
【０００１】[0001]
【発明の属する技術分野】本発明は、酸化物超電導体を
用いたジョセフソン素子およびその製造方法に関し、特
に双結晶基板を用いたジョセフソン素子およびその製造
方法に関する。The present invention relates to a Josephson device using an oxide superconductor and a method for manufacturing the same, and more particularly, to a Josephson device using a double crystal substrate and a method for manufacturing the same.
【０００２】[0002]
【従来の技術】YBaCuO、BiSrCaCuO 、TlBaCaCuO のよう
な酸化物超電導体を応用した電子デバイスに、ジョセフ
ソン効果を利用したジョセフソン素子がある。このジョ
セフソン素子の製造方法に、例えばD. Dimos等によっ
て、Phys. Rev. Lett. Vol. 61，P219-222(1998)に示さ
れたバイクリスタル接合方法がある。2. Description of the Related Art There is a Josephson element utilizing the Josephson effect as an electronic device to which an oxide superconductor such as YBaCuO, BiSrCaCuO or TlBaCaCuO is applied. As a method of manufacturing the Josephson element, there is a bicrystal bonding method described by D. Dimos and others in Phys. Rev. Lett. Vol. 61, P219-222 (1998).
【０００３】バイクリスタル接合方法では、例えばSrTi
O3の（１００）面を表面とする２枚の結晶板を、互いに
その結晶方位を異ならせて張り合わせた後、これに熱処
理を施して形成された双結晶基板が用いられる。双結晶
基板の接合線が露出する表面に、酸化物超電導薄膜がエ
ピタキシャル成長されると、接合線上に、酸化物超電導
薄膜の粒界接合が形成される。この粒界接合は、ジョセ
フソン効果を示すことから、粒界接合を含む酸化物超電
導薄膜を所望パターンに成形することにより、ジョセフ
ソン素子が形成される。In the bicrystal bonding method, for example, SrTi
A two-crystal substrate formed by bonding two crystal plates having the (100) plane of O 3 as a surface with different crystal orientations from each other and then performing a heat treatment on the two crystal plates is used. When the oxide superconducting thin film is epitaxially grown on the surface of the twin crystal substrate where the bonding line is exposed, a grain boundary junction of the oxide superconducting thin film is formed on the bonding line. Since the grain boundary junction exhibits the Josephson effect, a Josephson element is formed by forming the oxide superconducting thin film including the grain boundary junction into a desired pattern.
【０００４】[0004]
【発明が解決しようとする課題】しかしながら、前記し
たような従来のバイクリスタル接合方法によって得られ
たジョセフソン素子は、その特性にばらつきが生じやす
く、ほぼ均等な特性のジョセフソン素子を製造する上
で、その再現性に問題があった。そこで、本発明は、ほ
ぼ均等で良好な特性を示すジョセフソン素子、およびこ
の良好な特性を示すジョセフソン素子を再現性良く製造
し得る製造方法を提供することを企図する。However, the characteristics of the Josephson element obtained by the above-mentioned conventional bicrystal bonding method are liable to vary, and the Josephson element having substantially uniform characteristics can be manufactured. Thus, there was a problem in its reproducibility. Therefore, the present invention intends to provide a Josephson device exhibiting substantially uniform and good characteristics, and a method of manufacturing a Josephson device exhibiting such good characteristics with good reproducibility.
【０００５】[0005]
【課題を解決するための手段】本願発明者は、バイクリ
スタル接合方法におけるジョセフソン素子の特性のばら
つきが、酸化物超電導薄膜が成長される双結晶基板に原
因があることをつきとめた。この双結晶基板の接合線
は、その上に成長される酸化物超電導薄膜に、ジョセフ
ソン効果を示す粒界接合を形成する上で、不可欠ではあ
る。しかしながら、この接合線が例えば０．８μｍを越
えるような幅寸法を有する双結晶基板上に成長させた酸
化物超電導薄膜からなるジョセフソン素子では、臨界温
度以下の低温領域で、抵抗が残留し、この残留抵抗によ
る特性の低下を招くことが判明した。The inventor of the present application has found that the variation in the characteristics of the Josephson element in the bicrystal bonding method is caused by the bicrystal substrate on which the oxide superconducting thin film is grown. The bonding line of the twin crystal substrate is indispensable for forming a grain boundary junction exhibiting the Josephson effect in the oxide superconducting thin film grown thereon. However, in a Josephson device composed of an oxide superconducting thin film grown on a bicrystalline substrate having a width dimension such that the bonding line exceeds 0.8 μm, for example, the resistance remains in a low temperature region below the critical temperature, It has been found that this residual resistance causes deterioration of characteristics.
【０００６】そこで、本発明は、次の構成を採用する。 〈構成〉本発明は、基本的には、双結晶基板の接合線が
露出する表面に酸化物超電導薄膜を成長させるジョセフ
ソン素子およびその製造方法において、双結晶基板とし
て、その接合線の幅寸法が０．８μｍ以下の双結晶基板
を用いることを特徴とする。Therefore, the present invention employs the following configuration. <Structure> The present invention basically provides a Josephson device for growing an oxide superconducting thin film on a surface where a bonding line of a bicrystal substrate is exposed, and a method of manufacturing the same, wherein the width of the bonding line is defined as a bicrystal substrate. Is characterized by using a bicrystalline substrate having a thickness of 0.8 μm or less.
【０００７】〈作用〉本発明では、双結晶基板の接合線
の幅寸法が０．８μｍ以下の良質な双結晶基板が選択さ
れ、選択された良質の双結晶基板上に、酸化物超電導薄
膜が成長される。これにより、双結晶基板の接合線に沿
って、酸化物超電導薄膜に良質な粒界接合が形成され
る。その結果、本発明によれば、臨界温度以下の低温領
域で電気抵抗が残留しない、良質なジョセフソン素子が
得られ、また、この良質なジョセフソン素子を確実かつ
比較的容易に形成することが可能となる。<Function> In the present invention, a high-quality bicrystal substrate having a junction line width dimension of 0.8 μm or less is selected, and an oxide superconducting thin film is formed on the selected high-quality bicrystal substrate. Be grown. Thereby, a high-quality grain boundary junction is formed in the oxide superconducting thin film along the junction line of the bicrystal substrate. As a result, according to the present invention, it is possible to obtain a good-quality Josephson device in which electric resistance does not remain in a low-temperature region equal to or lower than the critical temperature, and to form this good-quality Josephson device reliably and relatively easily. It becomes possible.
【０００８】[0008]
【発明の実施の形態】以下、本発明を図示の実施の形態
について詳細に説明する。 〈具体例〉本発明に係るジョセフソン素子のための双結
晶基板の結晶材料として、例えばSrTiO3が用いられ、そ
の（１００）面を表面とする２枚の結晶板が、互いにそ
の結晶方位を２４度の角度で異ならせて張り合わせた
後、これに熱処理が施され、これにより多数の双結晶基
板が形成される。DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the illustrated embodiments. <Specific Example> For example, SrTiO 3 is used as a crystal material of a bicrystal substrate for the Josephson device according to the present invention, and two crystal plates having the (100) plane as a surface have the same crystal orientation. After bonding at different angles of 24 degrees, this is subjected to a heat treatment, whereby a number of bicrystalline substrates are formed.
【０００９】図１および図２は、このようにして形成さ
れた双結晶基板の接合線を、例えば光学顕微鏡（倍率：
１０００）を用いて撮影した顕微鏡写真である。本発明
に係るジョセフソン素子の製造方法に用いる、選別工程
により選択された双結晶基板の顕微鏡写真が図１に示さ
れており、選択から洩れた双結晶基板の顕微鏡写真が図
２に示されている。FIGS. 1 and 2 show a bonding line of the thus formed bicrystal substrate, for example, with an optical microscope (magnification:
1000) is a photomicrograph taken using the same method. FIG. 1 shows a micrograph of the bicrystal substrate selected in the sorting step used in the method for manufacturing a Josephson device according to the present invention, and FIG. 2 shows a micrograph of the bicrystal substrate that has been omitted from the selection. ing.
【００１０】選別工程で選択された本発明に係る双結晶
基板では、図１に示されているように、この顕微鏡写真
からは、位置確認のための十字線状のマーカａが視認で
きるに過ぎず、接合線は視認し難い。このように、１０
００倍の光学顕微鏡では視認し難い程に良質な接合線を
示す双結晶基板が選択される。この選択された双結晶基
板の接合線は、顕微鏡写真の拡大等の手段により、その
線幅を計測すると、０．８μｍ以下の極めて細幅であっ
た。In the bicrystal substrate according to the present invention selected in the sorting step, as shown in FIG. 1, the cross-shaped marker a for confirming the position is only visually recognizable from the micrograph. And the joint line is difficult to see. Thus, 10
A bicrystal substrate that exhibits a high-quality bonding line that is difficult to see with a 00 × optical microscope is selected. When the line width of the selected bonding line of the bicrystal substrate was measured by a means such as enlargement of a micrograph, the line was extremely narrow at 0.8 μm or less.
【００１１】これに対し、図２（ａ）および図２（ｂ）
に示された顕微鏡写真の双結晶基板は、選択から洩れた
基板である。これら選択から洩れた双結晶基板では、そ
れらの顕微鏡写真から明らかなように、接合線（ｂ、
ｃ）を比較的容易に視認できる。これらの接合線ｂおよ
びｃの幅寸法は、０．８μｍを大きく越える値であっ
た。On the other hand, FIGS. 2A and 2B
The bicrystal substrate in the micrograph shown in FIG. In the bicrystalline substrates that have escaped from these selections, the junction lines (b,
c) can be visually recognized relatively easily. The width dimension of these joining lines b and c was a value greatly exceeding 0.8 μm.
【００１２】選択された本発明に係る良質な双結晶基板
および比較のために図２に示したと同様な選択から洩れ
た双結晶基板の両者を用いて、本発明に係るジョセフソ
ン素子を適用した超電導量子干渉計（ＳＱＵＩＤ）を作
成した。The Josephson device according to the present invention was applied using both the selected good-quality bicrystalline substrate according to the present invention and the twin crystal substrate leaked from the same selection as shown in FIG. 2 for comparison. A superconducting quantum interferometer (SQUID) was created.
【００１３】図３ないし図８は、そのＳＱＵＩＤの製造
方法を示す工程図である。選別工程で選択された良質な
双結晶基板１０は、図３（ａ）および図３（ｂ）に示さ
れているように、図１に示した１０００倍の顕微鏡写真
でも観察し難い０．８μｍ以下という極めて細幅の接合
線１１を有する。FIGS. 3 to 8 are process diagrams showing a method for manufacturing the SQUID. As shown in FIGS. 3 (a) and 3 (b), the high-quality bicrystal substrate 10 selected in the sorting step has a thickness of 0.8 μm which is difficult to observe even with the 1000 × microscope photograph shown in FIG. It has a very narrow joining line 11 as follows.
【００１４】選択工程により選別された双結晶基板１０
は、例えばアセトン、メチルアルコールを洗浄液とする
超音波洗浄を受けた後、結晶成長装置である例えば有機
金属気相成長装置を用いて、図４（ａ）および図４
（ｂ）に示されているように、接合線１１が露出する双
結晶基板１０の表面１０ａ上に、例えばYBaCuO7-X （YB
CO）からなる酸化物超電導薄膜１２が、４００ｎｍない
し５００ｎｍの厚さ寸法に成長される。The bicrystal substrate 10 selected by the selection process
4A and 4B are subjected to ultrasonic cleaning using, for example, acetone or methyl alcohol as a cleaning liquid, and then using a crystal growth apparatus such as a metal organic chemical vapor deposition apparatus.
As shown in (b), for example, a YBaCuO 7-X (YB
An oxide superconducting thin film 12 of CO) is grown to a thickness of 400 nm to 500 nm.
【００１５】酸化物超電導薄膜１２のための原料とし
て、Y 、Ba、およびCuのβジケトンキレートが用いら
れ、双結晶基板１０の基板温度は１０７３Ｋに保持さ
れ、成長速度として、７０ｎｍ／ｈまたは１００ｎｍ／
min が採用された。この酸化物超電導薄膜１２の成長に
より、接合線１１に沿って、その上に接合粒界１３が形
成される。As raw materials for the oxide superconducting thin film 12, β-diketone chelates of Y, Ba and Cu are used, the substrate temperature of the bicrystal substrate 10 is maintained at 1073K, and the growth rate is 70 nm / h or 100 nm. /
min has been adopted. By the growth of the oxide superconducting thin film 12, a bonding grain boundary 13 is formed on and along the bonding line 11.
【００１６】次に、１０上の酸化物超電導薄膜１２をＳ
ＱＵＩＤのための所定パターンに形成するために、図５
に示されているように、酸化物超電導薄膜１２上に、所
定形状のフォトレジスト１４が、従来よく知られたフォ
トリソグラフィを用いて形成される。Next, the oxide superconducting thin film 12 on
In order to form a predetermined pattern for the QUID, FIG.
As shown in FIG. 1, a photoresist 14 having a predetermined shape is formed on the oxide superconducting thin film 12 by using a well-known photolithography.
【００１７】フォトレジスト１４をエッチングマスクと
するドライエッチングにより、図６示されているよう
に、それぞれがジョセフソン効果を示す接合粒界１３を
含むブリッジ部１５ａおよび１５ｂを備えるＳＱＵＩＤ
のパターンが形成される。図示の例では、それぞれのブ
リッジ部１５ａ、１５ｂの幅寸法が７．５μｍに設定さ
れた２つのジョセフソン素子がループ状に結合されてお
り、そのループの大きさは５０×５０μｍ2 に設定され
ている。この例に限らず、ブリッジ部に種々の寸法を採
用することができる。As shown in FIG. 6, SQUIDs having bridge portions 15a and 15b each including a junction grain boundary 13 exhibiting the Josephson effect by dry etching using the photoresist 14 as an etching mask.
Is formed. In the illustrated example, two Josephson elements each having a width dimension of 7.5 μm for each of the bridge portions 15a and 15b are coupled in a loop shape, and the size of the loop is set to 50 × 50 μm 2. ing. Not limited to this example, various dimensions can be adopted for the bridge portion.
【００１８】その後、図７に示すように、例えば金ある
いは銀のようなオーミック接触を得るための電極１６
が、前記したと同様なフォトリソグラフィ技術を用いて
形成され、これにより、ＳＱＵＩＤ１７が完成する。Thereafter, as shown in FIG. 7, an electrode 16 for obtaining an ohmic contact such as gold or silver is used.
Are formed by using the same photolithography technique as described above, whereby the SQUID 17 is completed.
【００１９】本発明に係る選択された双結晶基板１０を
用いて製造したジョセフソン素子と、その比較例として
図２に示した双結晶基板を用いて製造したジョセフソン
素子との特性の比較が、それぞれの温度と抵抗値との変
化特性について測定された。ただし、本発明に係るジョ
セフソン素子のブリッジ部１５ａおよび１５ｂの幅寸法
は、前記したとおり、７．５μｍであるが、他方、比較
例のそれは１５μｍである。Comparison of the characteristics between the Josephson device manufactured using the selected twin crystal substrate 10 according to the present invention and the Josephson device manufactured using the twin crystal substrate shown in FIG. 2 as a comparative example. And the change characteristics of each temperature and resistance value were measured. However, the width of the bridge portions 15a and 15b of the Josephson element according to the present invention is 7.5 μm as described above, while that of the comparative example is 15 μm.
【００２０】図８および図９に示すそれぞれのグラフの
Ｘ軸は、温度（Ｋ）を示し、Ｙ軸は抵抗値（Ω）を示
す。本発明に係るジョセフソン素子では、図８のグラフ
の特性線Ａで示されているように、臨界温度であるほぼ
８５Ｋから温度が低下すると、抵抗値が零へ向けて急激
に変化しており、その臨界温度以下の温度領域では、残
留抵抗が零となり、良好な超導電特性を示す。8 and 9, the X-axis indicates temperature (K) and the Y-axis indicates resistance (Ω). In the Josephson device according to the present invention, as shown by the characteristic line A in the graph of FIG. 8, when the temperature decreases from the critical temperature of approximately 85 K, the resistance value rapidly changes toward zero. In a temperature range below the critical temperature, the residual resistance becomes zero, indicating good superconductivity.
【００２１】これに対し、比較例では、図９のグラフの
特性線Ｂで示されているように、臨界温度であるほぼ８
５Ｋから温度が低下すると、抵抗値が低減するものの、
図８に示される特性線Ａにおける程に急激に低下するこ
とはなく、しかも直ちに零になることはない。そのた
め、臨界温度以下での抵抗値は、その温度の低下に伴い
Ｘ軸に平行に変化することなく、角度θの傾斜に沿って
漸減することから、この抵抗分が、例えば４０Ｋという
低温まで、残留抵抗として残ることとなる。このことか
ら、比較例では、本願発明に係るジョセフソン素子にお
けるような良好な超電導特性を得ることはできない。On the other hand, in the comparative example, as shown by the characteristic line B in the graph of FIG.
When the temperature decreases from 5K, although the resistance value decreases,
It does not decrease as sharply as the characteristic line A shown in FIG. 8 and does not immediately become zero. Therefore, the resistance value below the critical temperature does not change in parallel with the X-axis as the temperature decreases, but gradually decreases along the inclination of the angle θ. It will remain as residual resistance. For this reason, in the comparative example, good superconductivity cannot be obtained as in the Josephson element according to the present invention.
【００２２】図１０は、図３ないし図７に示した工程に
よって得られた本発明に係るＳＱＵＩＤの電圧−磁束変
化特性を示すグラフである。ＳＱＵＩＤの特性を調べる
ために、このＳＱＵＩＤに、その電極１６および１６を
経て定電流を供給した状態で、順次、増大する磁束を作
用させる。この磁束の増大に応じて、端子間電圧値が、
周期的に変化すれば、良好なＳＱＵＩＤが形成されてい
る、すなわち、良好なジョセフソン素子が形成されてい
ることが分かる。FIG. 10 is a graph showing a voltage-magnetic flux change characteristic of the SQUID according to the present invention obtained by the steps shown in FIGS. In order to investigate the characteristics of the SQUID, a magnetic flux that increases sequentially is applied to the SQUID while a constant current is supplied through the electrodes 16 and 16. According to the increase of the magnetic flux, the voltage value between the terminals becomes
If it changes periodically, it is understood that a good SQUID is formed, that is, a good Josephson element is formed.
【００２３】図１０のグラフのＸ軸はＳＱＵＩＤに作用
する磁束（Ｗｂ）を示し、Ｙ軸はＳＱＵＩＤの端子間電
圧（μＶ）を示す。図１０のグラフの特性線Ｃは、ＳＱ
ＵＩＤへの定電流として−４００μＡの直流電流を供給
したときの電圧特性変化を示し、特性線Ｄは、同様な定
電流として−４５０μＡの直流電流を供給したときの電
圧変化特性を示す。いずれの特性線ＣおよびＤにおいて
も、量子化された磁束Φ0 （＝２．０７×１０-15 Ｗ
ｂ）に対応する周期的な電圧変化（図１０のグラフに
は、１０Φ0 のスパンが符号１７で示されている）が観
測されることから、良好なＳＱＵＩＤが得られており、
このＳＱＵＩＤのために良好なジョセフソン素子が形成
されていることが理解できよう。The X-axis of the graph of FIG. 10 shows the magnetic flux (Wb) acting on the SQUID, and the Y-axis shows the voltage (μV) between the terminals of the SQUID. The characteristic line C in the graph of FIG.
A voltage characteristic change when a DC current of −400 μA is supplied as a constant current to the UID is shown, and a characteristic line D shows a voltage change characteristic when a DC current of −450 μA is supplied as the same constant current. In each of the characteristic lines C and D, the quantized magnetic flux Φ 0 (= 2.07 × 10 −15 W
Since a periodic voltage change corresponding to b) (a span of 10Φ 0 is indicated by reference numeral 17 in the graph of FIG. 10) is observed, a good SQUID is obtained.
It can be seen that a good Josephson element is formed for this SQUID.
【００２４】双結晶基板１０の結晶面あるいは方位のず
れは、一例に過ぎず、これらは適宜選択することができ
る。また、基板材料として、SrTiO3の他、MgO 、YSZ
（イットリゥム安定化ジルコニア）、NdGaO3等の種々の
基板材料を使用することができる。また、酸化物超電導
薄膜材料として、BiSrCaCuO のようなBi系あるいはTlBa
CaCuO のようなTl系材料を用いることができる。また、
これら酸化物超電導薄膜の成長方法として、前記したＭ
ＯＣＶＤ法の他、スパッタ法、レーザアブレーション
法、分子線エピタキシー（ＭＢＥ）法等を適宜選択する
ことができる。さらに、前記したところでは、本発明を
ＳＱＵＩＤに適応した例について説明したが、これに限
らず、種々のジョセフソン素子応用デバイスに適用する
ことができる。The shift of the crystal plane or orientation of the bicrystal substrate 10 is merely an example, and these can be selected as appropriate. In addition, as a substrate material, in addition to SrTiO 3 , MgO, YSZ
(Yttrium stabilized zirconia), various substrate materials such as NdGaO 3 can be used. In addition, Bi-based materials such as BiSrCaCuO or TlBa
Tl-based materials such as CaCuO can be used. Also,
As a method for growing these oxide superconducting thin films, M
In addition to the OCVD method, a sputtering method, a laser ablation method, a molecular beam epitaxy (MBE) method, or the like can be appropriately selected. Furthermore, in the above description, the example in which the present invention is applied to the SQUID has been described. However, the present invention is not limited to this, and can be applied to various Josephson device application devices.
【００２５】[0025]
【発明の効果】本発明によれば、前記したように、双結
晶基板の接合線の幅寸法が０．８μｍ以下の良質な双結
晶基板が選択して用いられていることから、この良質な
接合線に沿って、酸化物超電導薄膜に良質な粒界接合が
形成され、これにより、臨界温度以下の低温領域で電気
抵抗が残留しない、良質なジョセフソン素子を確実かつ
比較的容易に形成することが可能となる。According to the present invention, as described above, a high-quality bicrystalline substrate having a width dimension of the bonding line of the bicrystalline substrate of 0.8 μm or less is selected and used. A high-quality grain boundary junction is formed in the oxide superconducting thin film along the bonding line, thereby reliably and relatively easily forming a high-quality Josephson device in which electric resistance does not remain in a low-temperature region below the critical temperature. It becomes possible.
【００２６】また、本発明によれば、残留抵抗を示すこ
とのない良好なジョセフソン素子を得ることができるこ
とから、このジョセフソン素子を例えばＳＱＵＩＤのよ
うな種々のジョセフソン効果を利用した電子デバイスに
応用することにより、優れた特性の電子デバイスを得る
ことができる。Further, according to the present invention, a good Josephson element having no residual resistance can be obtained. Therefore, the Josephson element can be replaced with an electronic device utilizing various Josephson effects such as SQUID. By applying it to an electronic device, an electronic device having excellent characteristics can be obtained.
【図１】本発明に係る双結晶基板の顕微鏡写真である。FIG. 1 is a micrograph of a bicrystal substrate according to the present invention.
【図２】比較例を示す双結晶基板の顕微鏡写真である。FIG. 2 is a micrograph of a bicrystal substrate showing a comparative example.
【図３】選択された本発明に係る双結晶基板を示し、図
３（ａ）は双結晶基板の平面図であり、図３（ｂ）は双
結晶基板の側面図である。3 shows a selected bicrystal substrate according to the present invention, FIG. 3 (a) is a plan view of the bicrystal substrate, and FIG. 3 (b) is a side view of the bicrystal substrate.
【図４】本発明に係る酸化物超電導薄膜の形成工程を示
し、図４（ａ）および図４（ｂ）はそれぞれ平面図およ
び側面図である。FIG. 4 shows a step of forming an oxide superconducting thin film according to the present invention, and FIGS. 4 (a) and 4 (b) are a plan view and a side view, respectively.
【図５】本発明に係るフォトリソ工程を示し、図５
（ａ）および図５（ｂ）はそれぞれ平面図および側面図
である。5 shows a photolithography process according to the present invention, and FIG.
5A and 5B are a plan view and a side view, respectively.
【図６】本発明に係るパターン形成工程を示し、図６
（ａ）および図６（ｂ）はそれぞれ平面図および側面図
である。FIG. 6 shows a pattern forming step according to the present invention, and FIG.
6A and 6B are a plan view and a side view, respectively.
【図７】本発明に係る電極形成工程を示し、図７（ａ）
および図７（ｂ）はそれぞれ平面図および側面図であ
る。FIG. 7 shows an electrode forming step according to the present invention, and FIG.
FIG. 7B is a plan view and a side view, respectively.
【図８】本発明に係るジョセフソン素子の温度−抵抗特
性を示すグラフである。FIG. 8 is a graph showing temperature-resistance characteristics of the Josephson element according to the present invention.
【図９】比較例の温度−抵抗特性を示すグラフである。FIG. 9 is a graph showing temperature-resistance characteristics of a comparative example.
【図１０】本発明に係るＳＱＵＩＤの電圧−磁束特性を
示すグラフである。FIG. 10 is a graph showing voltage-magnetic flux characteristics of the SQUID according to the present invention.
１０ 双結晶基板 １１ 接合線 １２ 酸化物超電導薄膜 １３ 接合粒界 Reference Signs List 10 Bicrystalline substrate 11 Bonding line 12 Oxide superconducting thin film 13 Bonding grain boundary
Claims (2)
化物超電導薄膜を成長させて得られるジョセフソン素子
であって、前記接合線の幅寸法が０．８μｍ以下である
ことを特徴とするジョセフソン素子。1. A Josephson element obtained by growing an oxide superconducting thin film on a surface of a bicrystalline substrate where a bonding line is exposed, wherein a width dimension of the bonding line is 0.8 μm or less. Josephson element.
ｍ以下の基板を選択すること、選択された双結晶基板の
接合線が露出する表面に酸化物超電導薄膜を成長させて
ジョセフソン素子を形成することを含むジョセフソン素
子の製造方法。2. The method according to claim 1, wherein the width dimension of the bonding line of the bicrystal substrate is 0.8 μm.
m. A method for manufacturing a Josephson device, comprising: selecting a substrate of m or less; and growing a Josephson device by growing an oxide superconducting thin film on a surface of the selected bicrystal substrate where the bonding line is exposed.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP9050931A JPH10233535A (en) | 1997-02-19 | 1997-02-19 | Josephson element and its manufacture |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP9050931A JPH10233535A (en) | 1997-02-19 | 1997-02-19 | Josephson element and its manufacture |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH10233535A true JPH10233535A (en) | 1998-09-02 |
Family
ID=12872575
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP9050931A Pending JPH10233535A (en) | 1997-02-19 | 1997-02-19 | Josephson element and its manufacture |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH10233535A (en) |
-
1997
- 1997-02-19 JP JP9050931A patent/JPH10233535A/en active Pending
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