JP2821761B2 - Patterning method for bridge-type grain boundary Josephson device composed of oxide superconducting film - Google Patents
Patterning method for bridge-type grain boundary Josephson device composed of oxide superconducting filmInfo
- Publication number
- JP2821761B2 JP2821761B2 JP1070498A JP7049889A JP2821761B2 JP 2821761 B2 JP2821761 B2 JP 2821761B2 JP 1070498 A JP1070498 A JP 1070498A JP 7049889 A JP7049889 A JP 7049889A JP 2821761 B2 JP2821761 B2 JP 2821761B2
- Authority
- JP
- Japan
- Prior art keywords
- bridge
- oxide superconducting
- superconducting film
- grain boundary
- molybdenum
- 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 - Lifetime
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- Inorganic Compounds Of Heavy Metals (AREA)
- Physical Vapour Deposition (AREA)
- Superconductor Devices And Manufacturing Methods Thereof (AREA)
Description
【発明の詳細な説明】 イ．産業上の利用分野 本発明は，基板表面にレジストとしてモリブデンを用
いたドライリフトオフ法による酸化物超伝導膜から成る
ブリッジ型粒界ジョセフソン素子のパターニング方法に
関する。DETAILED DESCRIPTION OF THE INVENTION BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for patterning a bridge type grain boundary Josephson device composed of an oxide superconducting film by a dry lift-off method using molybdenum as a resist on a substrate surface.
ロ．従来の技術 たとえば，基板に酸化物超伝導体を用いた膜状のブリ
ッジ型粒界ジョセフソン素子を作製する場合，従来の方
法は基板に酸化物超伝導体をスパッタ法やスクリーン印
刷法で膜を形成し，乾燥し，次いで900℃酸素雰囲気中
アニール処理した後，バンプおよびブリッジをケミカル
エッチング法あるいはレーザー法で成形していた。B. 2. Description of the Related Art For example, when fabricating a bridge-type grain boundary Josephson device using an oxide superconductor for a substrate, the conventional method uses an oxide superconductor on the substrate by sputtering or screen printing. Was formed, dried, and then annealed in an oxygen atmosphere at 900 ° C., and then the bumps and bridges were formed by a chemical etching method or a laser method.
ハ．発明が解決しようとする課題 特に，ブリッジ型粒界ジョセフソン素子は，ブリッジ
部の寸法によって，電磁波誘起ステップが明瞭に発現す
るか否かを決めるので，ブリッジ成形作業は入念に行わ
れていた。C. Problems to be Solved by the Invention In particular, since the bridge type grain boundary Josephson device determines whether or not the electromagnetic wave induced step clearly appears depending on the size of the bridge portion, the bridge forming operation has been carefully performed.
しかしながら，前述のケミカルエッチング法やレーザ
ー法は必ずしも最良の方法ではなかった。However, the above-described chemical etching method and laser method were not always the best methods.
すなわち，ケミカルエッチング法は基板に形成された
酸化物超伝導膜をパターニングするさい，バンクやブリ
ッジに相当する部分を有機レジスト（例えば，環化ゴム
−ビスアジドなど）でマスキングし感光したのち，リン
酸液でエッチングすることによって，不要酸化物超伝導
膜を除去する。そのさい，該不要膜を完全に除去するた
め，リン酸液に長時間接触させるので，周辺の必要な膜
まで浸蝕し，予定した酸化物超伝導膜の形状より小さく
なったり，あるいはポーラスになったりして，結果的
に，ブリッジ部の寸法にバラツキが生じ，明瞭なシャピ
ロステップが得られない場合があった。That is, in the chemical etching method, when an oxide superconducting film formed on a substrate is patterned, a portion corresponding to a bank or a bridge is masked with an organic resist (for example, cyclized rubber-bisazide or the like) and exposed to light. The unnecessary oxide superconducting film is removed by etching with a liquid. At that time, in order to completely remove the unnecessary film, it is kept in contact with a phosphoric acid solution for a long time, so that the surrounding necessary film is eroded and becomes smaller than the expected oxide superconducting film or becomes porous. As a result, the dimensions of the bridge portion may vary, and a clear Shapiro step may not be obtained.
また，レーザー法は，酸化物超伝導膜のうち，設計さ
れた素子パターン以外の不要部分をレーザー照射して，
超伝導性能を劣化させる方法である。しかし，この方法
は照射によって酸化物超伝導膜に生じた熱が周辺の該膜
にまで伝熱して劣化させた。そのため，設計通りのバン
プやブリッジのパターンがしばしば得られないという欠
点があった。The laser method irradiates unnecessary portions of the oxide superconducting film other than the designed device pattern with a laser,
This is a method of deteriorating superconductivity. However, in this method, the heat generated in the oxide superconducting film by the irradiation is transferred to the surrounding film and deteriorated. For this reason, there is a disadvantage that a bump or bridge pattern as designed is often not obtained.
ニ．課題を解決するための手段 そこで，本発明者らは前記従来法の欠点に鑑み，全く
別異の立場から酸化物超伝導膜から成るブリッジ型粒界
ジョセフソン素子のパターニング方法について鋭意検討
した結果，レジストとして熱によって昇華するモリブデ
ンを基板にネガパターニングした後，酸化物超伝導膜を
スパッタリングし加熱すると，所望の酸化物超伝導膜か
ら成るブリッジ型粒界ジョセフソン素子のパターンが得
られることを知見して本発明を完成させた。D. Means for Solving the Problems In view of the drawbacks of the conventional method, the present inventors have conducted intensive studies on a patterning method for a bridge-type grain boundary Josephson device composed of an oxide superconducting film from a completely different standpoint. After the substrate is negatively patterned with molybdenum, which sublimates due to heat as a resist, the oxide superconducting film is sputtered and heated to obtain a bridge-type grain boundary Josephson device pattern composed of the desired oxide superconducting film. The present invention has been completed based on the findings.
すなわち，本発明はモリブテンを用いてネガパターン
を形成したセラミックス基板表面に，酸化物超伝導体を
スパッタリングし，次いで500℃以上に加熱してスパッ
タリングした酸化物超伝導体をアニール処理すると同時
にモリブデンを昇華させたのち，モリブデン上に積層し
ていた酸化物超伝導体を除去することを特徴とする酸化
物超伝導膜から成るブリッジ型粒界ジョセフソン素子の
パターニング方法を要旨とするものである。That is, the present invention sputters an oxide superconductor on the surface of a ceramic substrate on which a negative pattern is formed using molybdenum, and then heats the oxide superconductor to a temperature of 500 ° C. or more to anneal the sputtered oxide superconductor and simultaneously remove molybdenum. An object of the present invention is to provide a method of patterning a bridge type grain boundary Josephson device comprising an oxide superconducting film, which comprises removing an oxide superconductor laminated on molybdenum after sublimation.
以下，本発明を詳細に説明する。 Hereinafter, the present invention will be described in detail.
モリブデン（Mo）は酸素雰囲気,500℃以上に加熱する
と三酸化モリブデン（MoO3）になると同時に昇華する。
本発明はその昇華現象を酸化物超伝導膜形成に応用した
ものである。When molybdenum (Mo) is heated to 500 ° C. or more in an oxygen atmosphere, it becomes molybdenum trioxide (MoO 3 ) and sublimates at the same time.
The present invention applies the sublimation phenomenon to the formation of an oxide superconducting film.
まず，セラミックス材料（例えばアルミナ，ムライ
ト，マグネシアなど）で平滑面を有する基板を常法にし
たがって成形する。First, a substrate having a smooth surface is formed of a ceramic material (for example, alumina, mullite, magnesia, etc.) according to a conventional method.
基板表面にスパッタリングなどの方法によってモリブ
デンの膜を形成する。その膜厚はあとで形成する酸化物
超伝導膜厚と同等ないし，それより少し厚めに形成する
のが好ましい。A molybdenum film is formed on the substrate surface by a method such as sputtering. The film thickness is preferably equal to or slightly larger than the oxide superconducting film thickness to be formed later.
次いで，常用されているホトレジスト（例えば，環化
ゴム−ビスアジトなど）をモリブデン膜上全面に塗布
し，乾燥したのち，所望形状に該当する部分を感光し，
引き続き，硝酸，リン酸などでエッチングを行う。その
結果，基板表面にモリブデン膜によるネガパターンが形
成される。Next, a commonly used photoresist (for example, cyclized rubber-bisazit) is applied to the entire surface of the molybdenum film, dried, and exposed to a portion corresponding to a desired shape.
Subsequently, etching is performed with nitric acid, phosphoric acid, or the like. As a result, a negative pattern of the molybdenum film is formed on the substrate surface.
その基板表面上に酸化物超伝導体をスパッタリング法
によって所望の厚さの膜を形成させる。このとき，もし
基板表面あるいはモリブデン表面に硝酸等が残存してい
ても，スパッタリングの過程でほぼ完全に飛散する。な
お，スパッタリング時に基板温度を200℃以上に加熱し
ておけば，酸化物超伝導膜の基板表面への付着もよく望
ましい。A film of a desired thickness is formed on the surface of the substrate by sputtering an oxide superconductor. At this time, even if nitric acid or the like remains on the substrate surface or the molybdenum surface, it is almost completely scattered during the sputtering process. Note that if the substrate temperature is heated to 200 ° C. or higher during sputtering, it is preferable that the oxide superconducting film adhere to the substrate surface.
以上のようにして得られた基板を，酸素雰囲気下,500
℃以上に加熱すると，ネガパターンを形成しているモリ
ブデンは酸素と反応して三酸化モリブデンを生成する一
方，昇華する。加熱温度を500℃未満にすると，モリブ
デンは昇華し難いので，好ましくない。加熱時間は温度
とモリブデンの厚さによって決まる。たとえば，三酸化
モリブデンの昇華は800℃付近から急激になり,900℃で
１分間に数十μｍの昇華速度である。なお，加熱温度は
スパッタリングした酸化物超伝導膜のアニール処理温度
と一致させて行えば，昇華とアニール処理の２工程を同
時に進行させるので，それだけ工程は簡略化され，製造
所要時間も短縮できるので一石二鳥である。The substrate obtained as described above was placed in an oxygen atmosphere at 500
When heated to a temperature of at least ° C., molybdenum forming the negative pattern reacts with oxygen to generate molybdenum trioxide, while sublimating. If the heating temperature is lower than 500 ° C., molybdenum is difficult to sublimate, which is not preferable. The heating time depends on the temperature and the thickness of the molybdenum. For example, the sublimation of molybdenum trioxide rapidly increases from around 800 ° C., at a sublimation rate of several tens μm per minute at 900 ° C. If the heating temperature is made to coincide with the annealing temperature of the sputtered oxide superconducting film, the two steps of sublimation and annealing are performed at the same time, which simplifies the process and shortens the time required for manufacturing. Two birds with one stone.
この際，昇華とともに酸化物超伝導膜も除去され，所
望のポジパターンを形成した酸化物超伝導膜から成るブ
リッジ型粒界ジョセフソン素子を有する基板が得られ
る。At this time, the oxide superconducting film is also removed along with the sublimation, and a substrate having a bridge type grain boundary Josephson element composed of the oxide superconducting film having a desired positive pattern is obtained.
本発明で使用する酸化物超伝導膜の材質はBa−La−Cu
−Ｏ系,Ba−Ｙ−Cu−Ｏ系,Ba−Er−Cu−Ｏ系,Bi−Sr−C
a−Cu−Ｏ系,Tl−Ba−Ca−Cu−Ｏ系など超伝導を示す酸
化物全てに適用でき，本発明において，その化合物を特
に限定するものではない。The material of the oxide superconducting film used in the present invention is Ba-La-Cu
-O system, Ba-Y-Cu-O system, Ba-Er-Cu-O system, Bi-Sr-C
The present invention can be applied to all oxides exhibiting superconductivity, such as a-Cu-O system and Tl-Ba-Ca-Cu-O system. In the present invention, the compound is not particularly limited.
以下，本発明を実施例に基づいて説明する。 Hereinafter, the present invention will be described based on examples.
ホ． 実施例 マグネシア基板上に，酸化物超伝導膜でブリッジ型粒
界ジョセフソン素子をパターニングした。E. Example A bridge type grain boundary Josephson device was patterned on a magnesia substrate with an oxide superconducting film.
成形されたマグネシア基板上に，モリブデンをスパッ
タリング法で１μｍの厚さに形成させたのち，レジスト
として環化ゴム−ビスアジドを塗布し，乾燥した。After forming molybdenum to a thickness of 1 μm on the formed magnesia substrate by a sputtering method, cyclized rubber-bisazide was applied as a resist and dried.
その表面を該ジョセフソン素子が得られるように感光
し，さらに，不要なモリブデンを５％リン酸溶液でエッ
チングを行ってネガパターンを形成した。The surface was exposed so that the Josephson element was obtained, and unnecessary molybdenum was etched with a 5% phosphoric acid solution to form a negative pattern.
しかるのち，基板を250℃に加熱しながら，ネガパタ
ーン側に，スパッタリング法によって厚さ１μｍのBa2Y
Cu3Oy膜を形成させた。Thereafter, while heating the substrate to 250 ° C., a 1 μm thick Ba 2 Y
A Cu 3 Oy film was formed.
続いて，大気中900℃,60分間加熱して，ネガを形成し
ているモリブデンを昇華させ、Ba2YCu3Oy膜からなるポ
ジパターンを得た。Subsequently, the substrate was heated in the air at 900 ° C. for 60 minutes to sublimate the molybdenum forming the negative to obtain a positive pattern composed of a Ba 2 YCu 3 Oy film.
そのパターンに10GHzのマイクロ波を照射したとき，
交流ジョセフソン効果を示す電磁波誘起ステップが観測
され，ブリッジ型粒界ジョセフソン素子が製作できたこ
とを確認した。When the pattern is irradiated with 10GHz microwave,
Electromagnetic wave induced steps showing the AC Josephson effect were observed, confirming that a bridge-type grain boundary Josephson device was fabricated.
ヘ．発明の効果 本発明はレジストとしてモリブデンを採用し，加熱に
よる酸化および昇華現象を利用した酸化物超伝導膜から
成るブリッジ型粒界ジョセフソン素子のパターニング方
法に係わり，従来法の欠点であったエッチング液の浸蝕
等による酸化物超伝導膜周辺の劣化を解消した。F. The present invention relates to a method of patterning a bridge type grain boundary Josephson device composed of an oxide superconducting film using molybdenum as a resist and utilizing an oxidation and sublimation phenomenon by heating, which is a disadvantage of the conventional method. Deterioration around the oxide superconducting film due to erosion of the liquid is eliminated.
それゆえ，本法にしたがえば微細寸法の形状構造を作
製する必要のあるブリッジ型粒界ジョセフソン素子も容
易に製作可能であり，当業界への寄与は大きい。Therefore, according to the present method, a bridge-type grain boundary Josephson device that needs to fabricate a fine-sized shape structure can be easily produced, and the contribution to the industry is great.
───────────────────────────────────────────────────── フロントページの続き (56)参考文献 特開 昭63−220546（ＪＰ，Ａ) 特開 昭63−276822（ＪＰ，Ａ) 特開 昭64−43922（ＪＰ，Ａ) 特開 昭58−147034（ＪＰ，Ａ) (58)調査した分野(Int.Cl.6，ＤＢ名) H01L 27/18,39/00,39/22,39/24 H01L 21/306,21/308 ZAA──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-63-220546 (JP, A) JP-A-63-276822 (JP, A) JP-A-64-43922 (JP, A) JP-A-58-58 147034 (JP, A) (58) Fields investigated (Int. Cl. 6 , DB name) H01L 27 / 18,39 / 00,39 / 22,39 / 24 H01L 21 / 306,21 / 308 ZAA
Claims (1)
ミックス基板表面に、酸化物超伝導体をスパッタリング
し、次いで500℃以上に加熱してスパッタリングした酸
化物超伝導体をアニール処理すると同時にモリブデンを
昇華させたのち、モリブデン上に積層していた酸化物超
伝導体を除去する酸化物超伝導膜から成るブリッジ型粒
界ジョセフソン素子のパターニング方法。An oxide superconductor is sputtered on the surface of a ceramic substrate on which a negative pattern is formed with molybdenum, and then heated to 500 ° C. or more to anneal the sputtered oxide superconductor and at the same time sublimate molybdenum. Thereafter, a method of patterning a bridge-type grain boundary Josephson device comprising an oxide superconductor film for removing the oxide superconductor laminated on molybdenum.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP1070498A JP2821761B2 (en) | 1989-03-24 | 1989-03-24 | Patterning method for bridge-type grain boundary Josephson device composed of oxide superconducting film |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP1070498A JP2821761B2 (en) | 1989-03-24 | 1989-03-24 | Patterning method for bridge-type grain boundary Josephson device composed of oxide superconducting film |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH02252680A JPH02252680A (en) | 1990-10-11 |
| JP2821761B2 true JP2821761B2 (en) | 1998-11-05 |
Family
ID=13433251
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP1070498A Expired - Lifetime JP2821761B2 (en) | 1989-03-24 | 1989-03-24 | Patterning method for bridge-type grain boundary Josephson device composed of oxide superconducting film |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP2821761B2 (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113629181A (en) * | 2021-07-23 | 2021-11-09 | 中国科学院电工研究所 | MgB2Preparation method of superconducting microbridge |
Family Cites Families (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS58147034A (en) * | 1982-02-26 | 1983-09-01 | Nippon Telegr & Teleph Corp <Ntt> | Formation of film in semiconductor device |
| JPS63276822A (en) * | 1987-05-06 | 1988-11-15 | Furukawa Electric Co Ltd:The | Patterning method for superconductive thin film |
| JPS6443922A (en) * | 1987-08-12 | 1989-02-16 | Hitachi Ltd | Formation of superconductive thin film |
| JPS63220546A (en) * | 1987-11-09 | 1988-09-13 | Semiconductor Energy Lab Co Ltd | Manufacture of superconducting device |
-
1989
- 1989-03-24 JP JP1070498A patent/JP2821761B2/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| JPH02252680A (en) | 1990-10-11 |
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