JPH0761869B2 - Method for manufacturing high temperature superconducting thin film - Google Patents
Method for manufacturing high temperature superconducting thin filmInfo
- Publication number
- JPH0761869B2 JPH0761869B2 JP63249623A JP24962388A JPH0761869B2 JP H0761869 B2 JPH0761869 B2 JP H0761869B2 JP 63249623 A JP63249623 A JP 63249623A JP 24962388 A JP24962388 A JP 24962388A JP H0761869 B2 JPH0761869 B2 JP H0761869B2
- Authority
- JP
- Japan
- Prior art keywords
- thin film
- substrate
- high temperature
- annealing
- superconducting thin
- 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
Links
Classifications
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E40/00—Technologies for an efficient electrical power generation, transmission or distribution
- Y02E40/60—Superconducting electric elements or equipment; Power systems integrating superconducting elements or equipment
Landscapes
- Inorganic Compounds Of Heavy Metals (AREA)
- Physical Vapour Deposition (AREA)
- Superconductor Devices And Manufacturing Methods Thereof (AREA)
- Superconductors And Manufacturing Methods Therefor (AREA)
Description
【発明の詳細な説明】 ＜産業上の利用分野＞ 本発明はTl（タリウム）系超伝導薄膜の製造方法の改善
に関するものである。DETAILED DESCRIPTION OF THE INVENTION <Field of Industrial Application> The present invention relates to an improvement in a method for producing a Tl (thallium) -based superconducting thin film.
＜従来の技術＞ Tl,Ba,Ca,Cu,Oxから構成されるTl系化合物は現在確認さ
れている安定した酸化物超伝導体の中では超伝導臨界温
度が絶対温度125Kと最も高いことが知られている。<Prior Art> Tl-based compounds composed of Tl, Ba, Ca, Cu, and Ox have the highest superconducting critical temperature of 125K absolute temperature among the stable oxide superconductors currently confirmed. Are known.
従来は上記化合物をターゲット材として用い，スパッタ
によりMgOの基板上に薄膜を形成し，その基板を高温熱
処理（以下，アニールという）することにより超伝導性
を得ている。Conventionally, the above compound is used as a target material, a thin film is formed on a MgO substrate by sputtering, and the substrate is subjected to high-temperature heat treatment (hereinafter referred to as annealing) to obtain superconductivity.
しかしながら,Tlは非常に毒性が高く,Tlを含むターゲッ
ト材をスパッタにより着膜した場合，スパッタ装置内
（真空室や排気系等）が汚染され，作業上危険を伴うと
いう問題があった。また，スパッタしたままの状態では
結晶構造が乱れているので超伝導性を有していない。結
晶構造を整えるためにはアニールをする必要があるが，
アニールするために基板を900℃程度に加熱するとTlが
蒸発してしまい，十分な超伝導性を得るのは難しいとい
う問題があった。However, Tl is extremely toxic, and when a target material containing Tl is deposited by sputtering, the inside of the sputtering equipment (vacuum chamber, exhaust system, etc.) is contaminated, which poses a problem in terms of work. In addition, since the crystal structure is disordered in the as-sputtered state, it does not have superconductivity. Annealing is necessary to arrange the crystal structure,
When the substrate is heated to about 900 ° C for annealing, Tl evaporates, making it difficult to obtain sufficient superconductivity.
この問題を解決するために本出願人は昭和63年９月26日
に“高温超伝導薄膜の製造方法”を出願した。その内容
は，スパッタによる薄膜形成はTlを含まない化合物で行
い，アニールをTl蒸気中で行うことによりスパッタによ
る装置内部の汚染を防止すると共に十分な超伝導性を有
する様にしたものである。In order to solve this problem, the applicant of the present invention applied for “Method for producing high temperature superconducting thin film” on September 26, 1988. The content of this is that thin film formation by sputtering is performed with a compound that does not contain Tl, and annealing is performed in Tl vapor to prevent contamination inside the device due to sputtering and to have sufficient superconductivity.
＜発明が解決しようとする課題＞ しかしながら，上記出願においてはスパッタでBa,Ca,C
u,Oの薄膜を形成後はその真空雰囲気から基板を取出す
訳であるが，アニールを行うまでの間は大気に晒される
ことになる。そのため特に湿気の多い日やアニールを行
うまで長期間放置しておくような場合は薄膜の表面が変
色し，この変色した薄膜をアニールしても良好な超伝導
特性を示さないという問題があった。この原因は薄膜中
のBa,Caが空気中のH2OやCO2と反応しているからと考え
られる。<Problems to be Solved by the Invention> However, in the above application, spattering of Ba, Ca, C
After forming the u, O thin film, the substrate is taken out of the vacuum atmosphere, but it is exposed to the atmosphere until annealing. Therefore, there is a problem that the surface of the thin film discolors especially on a humid day or when it is left for a long time until annealing, and even if the discolored thin film is annealed, good superconducting properties are not exhibited. . This is probably because Ba and Ca in the thin film react with H 2 O and CO 2 in the air.
本発明は上記従来技術の問題点に鑑みて成されたもの
で，薄膜形成からアニールまでの間の反応を防止する薄
膜を形成し，良好な高温超伝導薄膜を得ることを目的と
する。The present invention has been made in view of the above problems of the prior art, and an object of the present invention is to form a thin film that prevents a reaction between thin film formation and annealing and obtain a good high temperature superconducting thin film.
＜課題を解決するための手段＞ 上記課題を解決するための本発明の構成は， １）Ba,Ca,Cu,Oからなる化合物のターゲット材を用いて
単結晶基板上に第１の薄膜を形成する工程と， ２）前記薄膜上にCuからなるターゲット材を用いて第２
の薄膜を形成する工程と， ３）前記２層の薄膜が形成された単結晶基板をTl雰囲気
中で熱処理する工程により，前記薄膜中にTlを拡散させ
たことを特徴とするものである。<Means for Solving the Problems> The constitution of the present invention for solving the above problems is as follows: 1) A first thin film is formed on a single crystal substrate using a target material of a compound consisting of Ba, Ca, Cu, and O. Forming step, and 2) using a target material made of Cu on the thin film,
And a step of 3) heat treating the single crystal substrate on which the two-layer thin film is formed in a Tl atmosphere, to diffuse Tl in the thin film.
＜実施例＞ 本発明の一実施例について説明する。<Example> An example of the present invention will be described.
始めにマグネトロンスパッタ法により第１の薄膜として
のBa2Ca2Cu3Ox化合物を基板へ着膜する。First, a Ba 2 Ca 2 Cu 3 Ox compound as a first thin film is deposited on a substrate by a magnetron sputtering method.
スパッタ条件は下記の通りとした。The sputtering conditions were as follows.
容器中のArガス100％ スパッタガス圧力;30mTorr 基板材質；単結晶MgO RF電力;200W 基板加熱;200〜300℃ スパッタ時間;1時間 次にこの薄膜の上に第２の薄膜であるCuをスパッタす
る。なお，この場合スパッタ装置は２種類以上のターゲ
ットが装着可能な装置を用いるものとし,Ba,Ca,Cu,O薄
膜を形成後，この上にCuのターゲットを用いてCu薄膜を
形成する。即ち，基板を装置内から取出すことなく２層
のスパッタを行う。またCuの薄膜は極薄く行い例えば50
0〜1000Åの程度とする。Ar gas in container 100% Sputtering gas pressure; 30mTorr Substrate material; Single crystal MgO RF power; 200W Substrate heating; 200-300 ℃ Sputtering time; 1 hour Next, sputter a second thin film Cu on this thin film To do. In this case, the sputtering apparatus is assumed to be an apparatus capable of mounting two or more types of targets, and after forming a Ba, Ca, Cu, O thin film, a Cu thin film is formed on this by using a Cu target. That is, the two layers are sputtered without taking out the substrate from the inside of the apparatus. Also, the Cu thin film is extremely thin, for example 50
It should be about 0 to 1000Å.
次にこの基板を第１図に断面図で示す熱処理装置を用い
てアニールを行う。図において,1は石英管であり,2は石
英管を巻き回して形成された加熱装置である。3a,3bは
アルミナからなるボートであり，第２図の斜視図に示す
ように上下に分割され，重ねた状態で縁部に形成された
溝等により内部との気体の流通が行われるように形成さ
れている（流通溝は図では省略）。４は薄膜が形成され
たMgO基板,5は金属Tlまたは酸化Tlであり，これらはア
ルミナボートの中に配置される。6a,6bは石英管の中に
配置されたアルミナからなるキャップであり，気体の流
通が可能なように形成されている。矢印はO2の流通方向
を示している。Next, this substrate is annealed using the heat treatment apparatus shown in the sectional view of FIG. In the figure, 1 is a quartz tube, and 2 is a heating device formed by winding a quartz tube. 3a and 3b are boats made of alumina, which are divided into upper and lower parts as shown in the perspective view of FIG. It is formed (the flow groove is omitted in the figure). 4 is a MgO substrate on which a thin film is formed, 5 is a metal Tl or oxide Tl, and these are arranged in an alumina boat. 6a and 6b are caps made of alumina placed in a quartz tube, and are formed so that gas can flow. The arrow indicates the flow direction of O 2 .
アニールは第３図に示す条件により行った。即ち,120分
で905℃まで昇温し,10〜20分間保持後,180分で300℃ま
で降温して徐冷する。上記アニールによりアルミナボー
ト中のTlが蒸発し，その蒸発したTlが基板表面に形成さ
れた薄膜中に拡散する。アニールは酸素流量0.1〜0.2ml
/minの雰囲気中で行った。なお，キャップ6a,6bは蒸発
したTlをより長く石英管１内に滞留させてTlの雰囲気を
高めるために寄与する。Annealing was performed under the conditions shown in FIG. That is, the temperature is raised to 905 ° C in 120 minutes, held for 10 to 20 minutes, then lowered to 300 ° C in 180 minutes and gradually cooled. By the above annealing, Tl in the alumina boat is evaporated, and the evaporated Tl is diffused in the thin film formed on the substrate surface. Annealing oxygen flow rate 0.1-0.2ml
I went in the atmosphere of / min. The caps 6a and 6b contribute to increasing the atmosphere of Tl by allowing the evaporated Tl to stay in the quartz tube 1 longer.
上記の様なアニール装置はスパッタ装置の様にクリーン
ルームに配置する必要がなく，毒性のあるTl蒸気の処理
も比較的容易である。Unlike the sputtering system, the annealing system as described above does not need to be placed in a clean room, and the treatment of toxic Tl vapor is relatively easy.
第４図は上記方法により作製した超伝導薄膜の温度と抵
抗の関係を示すものである。図によれば臨界温度は100K
であり，液体窒素温度（77K）を23K上回っていることが
分る。なお，臨界温度の測定は超伝導薄膜に銀ペースト
を用いて電極を取出し液体ヘリウム中に配置して４端子
法により温度−抵抗測定を行った。また，本発明の製造
方法により複数回同様の超伝導薄膜を作製し温度−抵抗
測定を行ったが臨界温度の再現性は良好であった。FIG. 4 shows the relationship between temperature and resistance of the superconducting thin film produced by the above method. According to the figure, the critical temperature is 100K
It is found that the temperature is higher than the liquid nitrogen temperature (77K) by 23K. The critical temperature was measured by using a silver paste for the superconducting thin film, taking out the electrode, placing it in liquid helium, and measuring the temperature-resistance by the four-terminal method. Further, the same superconducting thin film was prepared by the manufacturing method of the present invention a plurality of times and the temperature-resistance was measured, but the reproducibility of the critical temperature was good.
なお，本実施例においては薄膜をマグネトロンスパッタ
法を用いて作製したが，薄膜形成装置の種類は任意であ
る。また，アニールの条件を具体的数値で示したが本実
施例に限るものではなく，より良好な値を得るために適
宜変更可能である。また，酸化化合物の構成はBa2Ca2Cu
3Oxに限ることなく他の組成でも良い。In this embodiment, the thin film was produced by using the magnetron sputtering method, but the type of thin film forming apparatus is arbitrary. Further, although the annealing conditions are shown by specific numerical values, they are not limited to the present embodiment, and may be changed as appropriate to obtain better values. The composition of the oxide compound is Ba 2 Ca 2 Cu.
The composition is not limited to 3 Ox, and other compositions may be used.
また，本実施例においては単結晶基板をMgOとしたが，
これに限ることなく例えばSrTiO3等でもよい。In addition, although the single crystal substrate is MgO in this example,
The material is not limited to this, and may be SrTiO 3 or the like.
また，本実施例ではTlを含まない薄膜を形成後Tl拡散を
行う工程をそれぞれ一工程で終了したが，この場合Tlは
表面の極浅い部分にしか拡散しない。用途に応じてTl拡
散を行った基板の上に更にTlを含まない薄膜をスパッタ
し，その上に更にTlを拡散することも可能である。この
場合，基板にはすでにTlが含まれているがTlは300℃程
度では蒸発しないので汚染の危険性はない。Further, in this embodiment, the steps of performing Tl diffusion after forming a thin film not containing Tl are completed in one step, but in this case, Tl diffuses only in the extremely shallow part of the surface. Depending on the application, it is also possible to sputter a thin film that does not contain Tl on the substrate on which Tl has been diffused, and to further diffuse Tl onto it. In this case, the substrate already contains Tl, but since Tl does not evaporate at around 300 ° C, there is no risk of contamination.
＜発明の効果＞ 以上，実施例とともに具体的に説明したように本発明に
よれば，スパッタによる薄膜形成からアニールを行うま
での間にBa−Ca−CuOx薄膜が反応するのを防止するCu薄
膜を形成したので良好な高温超伝導薄膜を得ることが出
来る。<Effects of the Invention> As described above in detail with reference to the embodiments, according to the present invention, a Cu thin film for preventing the reaction of the Ba-Ca-CuOx thin film between the thin film formation by sputtering and the annealing. As a result, the high temperature superconducting thin film can be obtained.
【図面の簡単な説明】 第１図はアニール装置の一実施例を示す図，第２図は基
板とTlを収納するボートを示す斜視図，第３図はアニー
ルの温度条件を示す図，第４図は薄膜の温度と抵抗の関
係を示す図である。 １……石英管,2……加熱装置,3a,3b……アルミナボー
ト,4……基板,5……Tl金属または酸化Tl。BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a diagram showing an embodiment of an annealing device, FIG. 2 is a perspective view showing a boat accommodating a substrate and Tl, and FIG. 3 is a diagram showing annealing temperature conditions. FIG. 4 is a diagram showing the relationship between temperature and resistance of the thin film. 1 ... Quartz tube, 2 ... Heating device, 3a, 3b ... Alumina boat, 4 ... Substrate, 5 ... Tl Metal or oxide Tl.
───────────────────────────────────────────────────── フロントページの続き (72)発明者 梅沢 俊匡 東京都武蔵野市中町２丁目９番32号 横河 電機株式会社内 (56)参考文献 特開 平１−294560（ＪＰ，Ａ) 特開 平２−46611（ＪＰ，Ａ) ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Shunji Umezawa 2-9-32 Nakamachi, Musashino-shi, Tokyo Yokogawa Electric Co., Ltd. (56) Reference JP-A-1-294560 (JP, A) JP Flat 2-46611 (JP, A)
Claims (3)
を用いて単結晶基板上に第１の薄膜を形成する工程と，1. A step of forming a first thin film on a single crystal substrate using a target material of a compound consisting of Ba, Ca, Cu, O,
いて第２の薄膜を形成する工程と，2. A step of forming a second thin film on the thin film by using a target material made of Cu,
Tl雰囲気中で熱処理する工程により，前記薄膜中にTlを
拡散させたことを特徴とする高温超伝導薄膜の製造方
法。3. A single crystal substrate on which the two-layer thin film is formed
A method of manufacturing a high temperature superconducting thin film, characterized in that Tl is diffused in the thin film by a heat treatment step in a Tl atmosphere.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP63249623A JPH0761869B2 (en) | 1988-10-03 | 1988-10-03 | Method for manufacturing high temperature superconducting thin film |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP63249623A JPH0761869B2 (en) | 1988-10-03 | 1988-10-03 | Method for manufacturing high temperature superconducting thin film |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH0297420A JPH0297420A (en) | 1990-04-10 |
| JPH0761869B2 true JPH0761869B2 (en) | 1995-07-05 |
Family
ID=17195781
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP63249623A Expired - Lifetime JPH0761869B2 (en) | 1988-10-03 | 1988-10-03 | Method for manufacturing high temperature superconducting thin film |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH0761869B2 (en) |
-
1988
- 1988-10-03 JP JP63249623A patent/JPH0761869B2/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| JPH0297420A (en) | 1990-04-10 |
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