JPH0675101B2 - SQUID element - Google Patents
SQUID elementInfo
- Publication number
- JPH0675101B2 JPH0675101B2 JP1215205A JP21520589A JPH0675101B2 JP H0675101 B2 JPH0675101 B2 JP H0675101B2 JP 1215205 A JP1215205 A JP 1215205A JP 21520589 A JP21520589 A JP 21520589A JP H0675101 B2 JPH0675101 B2 JP H0675101B2
- Authority
- JP
- Japan
- Prior art keywords
- thin film
- substrate
- squid
- ring
- temperature 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.)
- Expired - Fee Related
Links
Landscapes
- Measuring Magnetic Variables (AREA)
- Superconductor Devices And Manufacturing Methods Thereof (AREA)
Description
【発明の詳細な説明】 ＜産業上の利用分野＞ 本発明は高温超電導薄膜を用いたSQUID素子に関する。DETAILED DESCRIPTION OF THE INVENTION <Field of Industrial Application> The present invention relates to a SQUID element using a high temperature superconducting thin film.
なお、本発明のSQUID素子は、例えば生体の肺や心臓等
における磁気の検出、金属疲労や金属腐食等を検査する
材料試験、更には資源探査、あるいは地震予知等の、極
めて微弱な磁気の検出に適用することができる。Incidentally, the SQUID element of the present invention, for example, detection of magnetism in the lungs and heart of a living body, material test for inspecting metal fatigue, metal corrosion, etc., further resource exploration, or earthquake prediction, detection of extremely weak magnetism. Can be applied to.
＜従来の技術＞ YBCOに代表される高温超電導薄膜を用いたSQUID素子関
しては、既に多くの報告がなされているが、そのジョセ
フソン接合はいずれも実質的に粒界接合であり、粒界部
分での臨界電流密度が小さいことを利用して、弱結合部
たるジョセフソン接合を得ている。<Prior Art> Many reports have already been made on SQUID devices using high-temperature superconducting thin films represented by YBCO, but all Josephson junctions are grain boundary junctions. By utilizing the fact that the critical current density in the part is small, a Josephson junction, which is a weak coupling part, is obtained.
このことから、従来すでに発表されている高温超電導薄
膜製のSQUID素子では、高温超電導体の多結晶薄膜をパ
ターニングすることによって、超電導リングとジョセフ
ソン接合部を得ている。For this reason, in the SQUID element made of a high-temperature superconducting thin film that has been previously announced, the superconducting ring and the Josephson junction are obtained by patterning the polycrystalline thin film of the high-temperature superconductor.
＜発明が解決しようとする課題＞ ところで、高温超電導薄膜では、粒界が存在するとその
部分から薄膜内に磁束が侵入する。<Problems to be Solved by the Invention> In a high-temperature superconducting thin film, when a grain boundary exists, magnetic flux penetrates into the thin film from that portion.
従って、上記のような従来の高温超電導薄膜を用いたSQ
UID素子によれば、超電導リング部分にも磁束が侵入す
ることになり、その結果、磁場−出力電圧特性が安定せ
ず、ヒステリシス等が存在する。Therefore, SQ using the conventional high temperature superconducting thin film as described above
According to the UID element, the magnetic flux also penetrates into the superconducting ring portion, and as a result, the magnetic field-output voltage characteristic is not stable, and hysteresis or the like exists.
＜課題を解決するための手段＞ 本発明はより安定した動作を行うことのできる高温超電
導薄膜製のSQUID素子を得るためになさたもので、その
構成を実施例に対応する第１図を参照しつつ説明する
と、本発明では、基板１の一方の面に、高温超電導体の
粒界接合を利用したジョセフソン接合2aを含む所定パタ
ーンの薄膜SQUIDリング２を形成し、その基板１の他方
の面には、ジョセフソン接合2aに対応する箇所を除い
て、上記のSQUIDリング２のパターンと同じパターン
で、SQUIDリング２を形成する薄膜よりも高い臨界電流
値を有する高温超電導薄膜３を形成している。<Means for Solving the Problems> The present invention was made to obtain a SQUID element made of a high-temperature superconducting thin film capable of performing more stable operation, and its configuration is shown in FIG. 1 corresponding to the embodiment. That is, in the present invention, in the present invention, a thin film SQUID ring 2 having a predetermined pattern including a Josephson junction 2a utilizing the grain boundary junction of a high temperature superconductor is formed on one surface of the substrate 1, and the other surface of the substrate 1 is formed. A high-temperature superconducting thin film 3 having a critical current value higher than that of the thin film forming the SQUID ring 2 is formed on the surface in the same pattern as the SQUID ring 2 except for the portion corresponding to the Josephson junction 2a. ing.
＜作用＞ ジョセフソン接合2aを除いたSQUID2の超電導リング部2b
は、これと同じパターンでその裏面に形成された高温超
電導薄膜３によってシールドされ、磁束の侵入が阻止さ
れる。<Operation> Superconducting ring 2b of SQUID2 excluding Josephson junction 2a
Is shielded by the high-temperature superconducting thin film 3 formed on its back surface in the same pattern as this, and the penetration of magnetic flux is blocked.
＜実施例＞ 第１図は本発明実施例の構成を示す図で、（ａ）は表面
図、（ｂ）は裏面図、（ｃ）は側面図である。<Embodiment> FIG. 1 is a diagram showing a configuration of an embodiment of the present invention, (a) is a front view, (b) is a rear view, and (c) is a side view.
MgO（100）製の基板１の表面には、YBCO高温超電導薄膜
をパターニングして超電導リング部2bの一部のジョセフ
ソン接合2aを持つSQUIDリング２が形成されている。On a surface of a substrate 1 made of MgO (100), a SQUID ring 2 having a Josephson junction 2a which is a part of a superconducting ring portion 2b is formed by patterning a YBCO high temperature superconducting thin film.
このSQUIDリング２を形成する高温超電導薄膜は、第２
図にそのジョセフソン接合2a近傍の拡大図を模式的に示
すように、粒界Ｉを持つ多結晶膜であって、その結晶粒
径はジョセフソン接合2aの幅と長さにオーダー的にほぼ
等しい大きさを持っている。The high temperature superconducting thin film that forms this SQUID ring 2
As shown schematically in an enlarged view of the vicinity of the Josephson junction 2a in the figure, it is a polycrystalline film having a grain boundary I, and its crystal grain size is approximately the order of the width and length of the Josephson junction 2a. Have equal size.
基板１の裏面には、SQUIDリング２とほぼ同一のパター
ンを持つYBCO高温超電導薄膜３が形成されている。裏面
の高温超電導薄膜３のパターンが表面のSQUIDリング２
のパターンと相違する点は、第３図に示すように、SQUI
Dリング２のジョセフソン接合2aに対応する箇所には製
膜されていない点である。A YBCO high temperature superconducting thin film 3 having substantially the same pattern as the SQUID ring 2 is formed on the back surface of the substrate 1. The pattern of the high temperature superconducting thin film 3 on the back surface is the SQUID ring 2 on the front surface.
The difference from the pattern is that SQUI
The film is not formed on the part of the D ring 2 corresponding to the Josephson junction 2a.
そして、この高温超電導薄膜３は粒界の殆ど存在しない
実質的に単結晶膜であって、SQUIDリング２を形成する
超電導薄膜よりも高い臨界電流密度を持っている。The high temperature superconducting thin film 3 is a substantially single crystal film having few grain boundaries, and has a higher critical current density than the superconducting thin film forming the SQUID ring 2.
以上のような構造によれば、SQUIDリング２の超電導リ
ング部2bは、その裏面にこれと同一パターンで形成され
た臨界電流密度の高い、かつ、粒界の存在しない高温超
電導薄膜３によって磁気シールドされることになり、超
電導リング部2bが臨界電流密度の低い多結晶薄膜であっ
ても、ここに磁束が侵入することがない。According to the structure as described above, the superconducting ring portion 2b of the SQUID ring 2 is magnetically shielded by the high temperature superconducting thin film 3 having a high critical current density and having no grain boundary formed on the back surface thereof in the same pattern. Therefore, even if the superconducting ring portion 2b is a polycrystalline thin film having a low critical current density, the magnetic flux does not enter here.
次に以上の本発明実施例の製法を説明する。Next, the manufacturing method of the embodiment of the present invention will be described.
まず、両面研磨した基板１を用意し、基板１を加熱せず
にその表面にRFマグネトロンスパッタによりYBCO薄膜を
製膜する。First, a double-side polished substrate 1 is prepared, and a YBCO thin film is formed on the surface of the substrate 1 by RF magnetron sputtering without heating the substrate 1.
その後、基板１を加熱しながらRFマグネトロンスパッタ
を行うことによって、裏面側にYBCOのアズグロウン膜を
製膜する。Then, RF magnetron sputtering is performed while heating the substrate 1 to form an as-grown YBCO film on the back surface side.
次いで両面にYBCO薄膜が製膜された基板１をアニールす
ることによって、表面側のYBCO薄膜を結晶化してこれに
粒界を作成する。つまり、裏面にYBCOのポストアニール
膜を得るわけである。Then, the substrate 1 having YBCO thin films formed on both sides is annealed to crystallize the YBCO thin films on the front surface side to form grain boundaries in the YBCO thin films. In other words, a YBCO post-annealed film is obtained on the back surface.
次に、両面のYBCO薄膜上のフォトレジストを塗布し、フ
ォトリソ工程によって表裏両面に第１図に示すパターン
を残してレジストを除去する。このとき、表裏両面のパ
ターンの位置合わせを考慮した露光を行う必要がある
が、これは、両面同時露光装置を用い、あらかじめダミ
ーウエハで上下のフォトマスクの位置合わせをしておく
ことによって可能である。Next, a photoresist on the YBCO thin films on both surfaces is applied, and the resist is removed by a photolithography process leaving the pattern shown in FIG. At this time, it is necessary to perform exposure in consideration of the alignment of the patterns on the front and back sides, but this can be done by aligning the upper and lower photomasks with a dummy wafer in advance using a double-sided simultaneous exposure apparatus. .
そして、現像によって残されたレジスト膜をマスクとし
て、ドライエッチング（特にArイオンエッチングがベス
ト）によって第１図に示した構造の素子を得る。Then, using the resist film left by the development as a mask, an element having the structure shown in FIG. 1 is obtained by dry etching (particularly Ar ion etching is best).
なお、以上の工程において、表裏両面のパターニングの
後にアニールを行ってもよい。In the above steps, annealing may be performed after patterning both front and back surfaces.
また、本発明では、基板１は必ずしも一枚でなくてもよ
く、異なる基板に粒界SQUIDリング２とシールド体であ
る高温超電導薄膜３を別々に作成して、位置合わせをし
て貼り合わせてもよい。Further, in the present invention, the number of the substrate 1 is not necessarily one, and the grain boundary SQUID ring 2 and the high temperature superconducting thin film 3 as the shield are separately formed on different substrates and are aligned and bonded. Good.
更に、SQUIDリング２とそのシールド体である高温超電
導薄膜３は、YBCO薄膜に限らず、他の高温超電導薄膜で
あってもよいことは勿論であり、基板１の材料はMgOの
ほか、SrTiO3等、使用する高温超電導薄膜の成長が可能
な任意のものを使用できることは言うまでもない。Further, the SQUID ring 2 and the high-temperature superconducting thin film 3 that is the shield thereof are not limited to the YBCO thin film, and needless to say, may be other high-temperature superconducting thin films, and the material of the substrate 1 is MgO or SrTiO 3 Needless to say, any material that can grow the high-temperature superconducting thin film used can be used.
＜発明の効果＞ 以上で説明したように、本発明によれば、高温超電導薄
膜の粒界を利用したジョセフソン接合を有するSQUIDリ
ングが形成された基板の裏面に、そのジョセフソン接合
部分を除く超電導リング部と等しいパターンで、SQUID
リングを構成する超電導薄膜よりも臨界電流密度の高
い、換言すれば磁束の侵入しにくい超電導薄膜を形成し
たので、SQUIDリングの超電導リング部はその裏面の高
温超電導薄膜によって磁気シールドされ、ここに磁束が
侵入することがなくなり、動作の安定した高性能のSQUI
D素子が得られる。<Effects of the Invention> As described above, according to the present invention, the Josephson junction is removed from the back surface of the substrate on which the SQUID ring having the Josephson junction utilizing the grain boundaries of the high temperature superconducting thin film is formed. SQUID with the same pattern as the superconducting ring
Since a superconducting thin film with a higher critical current density than the superconducting thin film forming the ring, in other words, a magnetic flux that is hard to penetrate, was formed, the superconducting ring part of the SQUID ring is magnetically shielded by the high-temperature superconducting thin film on its back surface. High-performance SQUI with stable operation
D element is obtained.
第１図は本発明実施例の構成図で、（ａ）は表面図、
（ｂ）は裏面図、（ｃ）は側面図である。第２図はその
本発明実施例のSQUIDリング２の近傍の模式的拡大図、
第３図は同じく本発明実施例のジョセフソン接合2aの真
下部分近傍の裏面の高温超電導薄膜３の拡大図である。 １……基板 ２……SQUIDリング 2a……ジョセフソン接合 2b……超電導リング ３……高温超電導薄膜 Ｉ……粒界FIG. 1 is a configuration diagram of an embodiment of the present invention, (a) is a front view,
(B) is a rear view and (c) is a side view. FIG. 2 is a schematic enlarged view of the vicinity of the SQUID ring 2 of the embodiment of the present invention,
FIG. 3 is an enlarged view of the high temperature superconducting thin film 3 on the back surface in the vicinity of the portion just below the Josephson junction 2a of the embodiment of the present invention. 1 ... Substrate 2 ... SQUID ring 2a ... Josephson junction 2b ... Superconducting ring 3 ... High-temperature superconducting thin film I ... Grain boundary
───────────────────────────────────────────────────── フロントページの続き (56)参考文献 特開 平２−126173（ＪＰ，Ａ) 特開 昭64−15988（ＪＰ，Ａ) 特開 昭64−86574（ＪＰ，Ａ) 特開 昭59−210677（ＪＰ，Ａ) 特開 昭60−65582（ＪＰ，Ａ) 特開 昭61−182282（ＪＰ，Ａ) 特開 昭61−255077（ＪＰ，Ａ) 特開 昭62−285082（ＪＰ，Ａ) 特公 昭60−2796（ＪＰ，Ｂ２) ─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-2-126173 (JP, A) JP-A 64-15988 (JP, A) JP-A 64-86574 (JP, A) JP-A 59- 210677 (JP, A) JP 60-65582 (JP, A) JP 61-182282 (JP, A) JP 61-255077 (JP, A) JP 62-285082 (JP, A) Japanese Patent Sho 60-2796 (JP, B2)
Claims (1)
合を利用したジョセフソン接合を含む所定パターンの薄
膜SQUIDリングが形成され、その基板の他方の面には、
上記ジョセフソン接合に対応する箇所を除いて、上記パ
ターンと同じパターンで、上記薄膜よりも高い臨界電流
値を有する高温超電導薄膜が形成されてなる、SQUID素
子。1. A thin film SQUID ring having a predetermined pattern including a Josephson junction utilizing a grain boundary junction of a high temperature superconductor is formed on one surface of a substrate, and the other surface of the substrate is formed on the other surface of the substrate.
A SQUID element, wherein a high-temperature superconducting thin film having a critical current value higher than that of the above-mentioned thin film is formed in the same pattern as the above-mentioned pattern except for the portion corresponding to the above-mentioned Josephson junction.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP1215205A JPH0675101B2 (en) | 1989-08-21 | 1989-08-21 | SQUID element |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP1215205A JPH0675101B2 (en) | 1989-08-21 | 1989-08-21 | SQUID element |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH0378675A JPH0378675A (en) | 1991-04-03 |
| JPH0675101B2 true JPH0675101B2 (en) | 1994-09-21 |
Family
ID=16668434
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP1215205A Expired - Fee Related JPH0675101B2 (en) | 1989-08-21 | 1989-08-21 | SQUID element |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH0675101B2 (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP4936207B2 (en) * | 2005-12-06 | 2012-05-23 | 卓 加藤 | Carriage with stair-climbing assist mechanism |
| JPWO2010122733A1 (en) * | 2009-04-23 | 2012-10-25 | 国立大学法人豊橋技術科学大学 | SQUID magnetic sensor |
-
1989
- 1989-08-21 JP JP1215205A patent/JPH0675101B2/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| JPH0378675A (en) | 1991-04-03 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| LAPS | Cancellation because of no payment of annual fees |