JPH0393625A - Oxide superconductor thin film and production thereof - Google Patents
Oxide superconductor thin film and production thereofInfo
- Publication number
- JPH0393625A JPH0393625A JP1229917A JP22991789A JPH0393625A JP H0393625 A JPH0393625 A JP H0393625A JP 1229917 A JP1229917 A JP 1229917A JP 22991789 A JP22991789 A JP 22991789A JP H0393625 A JPH0393625 A JP H0393625A
- Authority
- JP
- Japan
- Prior art keywords
- thin film
- film
- oxide
- superconducting
- 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.)
- Granted
Links
- 239000010409 thin film Substances 0.000 title claims abstract description 64
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 15
- 239000002887 superconductor Substances 0.000 title description 7
- 239000000758 substrate Substances 0.000 claims abstract description 21
- 238000004544 sputter deposition Methods 0.000 claims abstract description 16
- 239000010949 copper Substances 0.000 claims abstract description 12
- 229910052802 copper Inorganic materials 0.000 claims abstract description 7
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 claims abstract description 6
- 229910052716 thallium Inorganic materials 0.000 claims abstract description 5
- BKVIYDNLLOSFOA-UHFFFAOYSA-N thallium Chemical compound [Tl] BKVIYDNLLOSFOA-UHFFFAOYSA-N 0.000 claims abstract description 4
- 229910052721 tungsten Inorganic materials 0.000 claims abstract description 4
- WFKWXMTUELFFGS-UHFFFAOYSA-N tungsten Chemical compound [W] WFKWXMTUELFFGS-UHFFFAOYSA-N 0.000 claims abstract description 3
- 239000010937 tungsten Substances 0.000 claims abstract description 3
- 230000008020 evaporation Effects 0.000 claims description 6
- 238000001704 evaporation Methods 0.000 claims description 6
- 239000002648 laminated material Substances 0.000 claims 2
- 239000010408 film Substances 0.000 abstract description 74
- 230000007704 transition Effects 0.000 abstract description 24
- 238000000034 method Methods 0.000 abstract description 10
- 238000010030 laminating Methods 0.000 abstract description 4
- 230000008569 process Effects 0.000 abstract description 4
- 229910052797 bismuth Inorganic materials 0.000 abstract description 3
- 238000009792 diffusion process Methods 0.000 abstract description 2
- 238000009413 insulation Methods 0.000 abstract description 2
- 229910052784 alkaline earth metal Inorganic materials 0.000 abstract 2
- 150000001342 alkaline earth metals Chemical class 0.000 abstract 2
- 229910002480 Cu-O Inorganic materials 0.000 abstract 1
- JCXGWMGPZLAOME-UHFFFAOYSA-N bismuth atom Chemical compound [Bi] JCXGWMGPZLAOME-UHFFFAOYSA-N 0.000 abstract 1
- 239000000463 material Substances 0.000 description 8
- 230000000694 effects Effects 0.000 description 7
- 230000000737 periodic effect Effects 0.000 description 7
- 238000010438 heat treatment Methods 0.000 description 6
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 description 4
- 150000001875 compounds Chemical class 0.000 description 4
- 239000013078 crystal Substances 0.000 description 4
- 238000000151 deposition Methods 0.000 description 4
- 229910014454 Ca-Cu Inorganic materials 0.000 description 3
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 3
- 238000010586 diagram Methods 0.000 description 3
- 238000003475 lamination Methods 0.000 description 3
- 239000001301 oxygen Substances 0.000 description 3
- 229910052760 oxygen Inorganic materials 0.000 description 3
- 229910004247 CaCu Inorganic materials 0.000 description 2
- 229910004369 ThO2 Inorganic materials 0.000 description 2
- 239000000956 alloy Substances 0.000 description 2
- 229910045601 alloy Inorganic materials 0.000 description 2
- 229910052786 argon Inorganic materials 0.000 description 2
- 238000007796 conventional method Methods 0.000 description 2
- 230000008021 deposition Effects 0.000 description 2
- 230000006866 deterioration Effects 0.000 description 2
- 239000007789 gas Substances 0.000 description 2
- 239000012212 insulator Substances 0.000 description 2
- 230000007246 mechanism Effects 0.000 description 2
- 239000000203 mixture Substances 0.000 description 2
- ZCUFMDLYAMJYST-UHFFFAOYSA-N thorium dioxide Chemical compound O=[Th]=O ZCUFMDLYAMJYST-UHFFFAOYSA-N 0.000 description 2
- 239000000919 ceramic Substances 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 210000000078 claw Anatomy 0.000 description 1
- 238000011109 contamination Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 229910052732 germanium Inorganic materials 0.000 description 1
- GNPVGFCGXDBREM-UHFFFAOYSA-N germanium atom Chemical compound [Ge] GNPVGFCGXDBREM-UHFFFAOYSA-N 0.000 description 1
- 239000012535 impurity Substances 0.000 description 1
- 230000003993 interaction Effects 0.000 description 1
- 238000001659 ion-beam spectroscopy Methods 0.000 description 1
- 238000001755 magnetron sputter deposition Methods 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 150000004767 nitrides Chemical class 0.000 description 1
- 239000002245 particle Substances 0.000 description 1
- 239000000843 powder Substances 0.000 description 1
- 238000005245 sintering Methods 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
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
- Superconductor Devices And Manufacturing Methods Thereof (AREA)
- Containers, Films, And Cooling For Superconductive Devices (AREA)
- Superconductors And Manufacturing Methods Therefor (AREA)
- Inorganic Compounds Of Heavy Metals (AREA)
- Physical Vapour Deposition (AREA)
Abstract
Description
【発明の詳細な説明】
産業上の利用分野
本発明１上 １００Ｋ以上の高臨界温度が期待されるタ
リウムを含む酸化物超電導体薄膜及びそのの製造方法に
関するものであも
従来の技術
高温超電導体として、Ａ１５型２元系化合物として窒化
ニオプ（ＮｂＮ）やゲルマニウム二オプ（ＮｂｓＧｅ）
などが知られていた力ｔ これらの材料の超電導転移温
度はたかだか２３Ｋであった方 ペロブス力イト系化合
物は さらに高い転移温度が期待さ％ Ｂａ−Ｌａ−
Ｃｕ−０系の高温超電導体が提案された ［シ０エイ、
シ０−、へ０ント１ノルツ及びケイ、エー、ミューラー
（Ｊ．Ｇ，Ｂｅｄｎｏｒｚ ａｎｄ Ｋ，Ａ，Ｍｕ
ｌｌｅｒ） ．７ｔイトシスリフト●７エア・７４シ
２−ク（Ｚｅｔｓｈｒｉｆｔ Ｆｕｒ Ｐｈｙｓｉ
ｋ Ｂ）一コンデ０冫スト”ｖター（Ｃｏｎｄｅｎｓ
ｅｄ Ｍａｔｔｅｒ） Ｖｏ１，６４，１８９−１
９３（１９８６）ｌｏさらに Ｂｉ−Ｓｒ−Ｃａ−Ｃｕ
−０系の材料がＩＯＯＫ以上の転移温度を示すことも発
見された［エイチ、マエタゝ、ワイ、タナカ、エム、７
クトミ及びデイ、アサノ （ Ｈ，Ｍａｅｄａ，Ｙ，Ｔ
ａｎａｋａ，Ｍ，Ｆｕｋｕｔｏｍｉ ａｎｄ Ｔ．
Ａｓａｎｏ） ，シ＊ ， 八− 二− Ｘ ＃ ，
シ＊ヤーナｋ−オ７”７７＠ライト９●７イシ０
フクス（Ｊａｐａｎｅｓｅ Ｊｏｕｒｎａｌ ｏｆ
Ａｐｐｌ一ｉｅｄ Ｐｈｙｓｉｃｓ）Ｖｏ１，２７
．Ｌ２０９−２１０（１９８８）］。加えてこのＢｉ系
よりも超電導転移温度の高いＴｌ−Ｂａ−Ｃａ−Ｃｕ一
〇系の材料が発見されるに至った［セゝ７ト、セ＃７ト
、シェンク゛及びエー、エム、ヘルマン （Ｚ，Ｚ．Ｓ
ｈｅｎｇ ａｎｄ Ａ．Ｍ．Ｈｅｒｍａｎｎ），ネ
イチｗ−（Ｎａｔｕｒｅ）Ｖｏｌ．３３２，１３８−１
３９（１９８８）．コ。 この種の材料の超電導機構
の詳細は明らかではない爪転移温度が室温以上に高くな
る可能性があり、高温超電導体として従来の２元系化合
物より、より有望な特性が期待されも
さらに超電導体と絶縁物とを交互に積層することにより
、より高い超電導転移温度が従来から期待されていた
［エム、エイチ、コーエン及びデ１イ、エイチ、ドウク
１ラス、シコニア （Ｍ．Ｈ．Ｃｏｈｅｎ ａｎｄ
Ｄ，Ｈ．Ｄｏｕｇｌａｓｓ，Ｊｒ．） ，７４シ１
ル・レヒコー・レタース”（Ｐｈｙｓｉｃａｌ Ｒｅ
ｖｉｅｗ Ｌｅｔｔｅｒｓ）Ｖｏｌ，１９，１１８−
１２１（１９６７）］。DETAILED DESCRIPTION OF THE INVENTION Industrial Field of Application The present invention 1 relates to a thallium-containing oxide superconductor thin film expected to have a high critical temperature of 100 K or higher and a method for producing the same. As A15 type binary compounds, nioptic nitride (NbN) and germanium dioptic (NbsGe) are used as A15 type binary compounds.
The superconducting transition temperature of these materials was at most 23 K, while the perovus force compound is expected to have an even higher transition temperature.Ba-La-
A Cu-0-based high-temperature superconductor was proposed [Shi0ei,
J.G., Bednorz and K.A., Mueller.
ller). 7t Itoshilift ●7 Air・74 Sheet (Zetshrift Fur Physi
k B) Condens
ed Matter) Vo1, 64, 189-1
93 (1986)lo further Bi-Sr-Ca-Cu
It was also discovered that -0 series materials exhibit a transition temperature higher than IOOK [H, Maeta, Y, Tanaka, M, 7
Kutomi and Day, Asano (H, Maeda, Y, T
Anaka, M., Fukutomi and T.
Asano), shi*, 8-2-X#,
Shi*yana k-o 7” 77 @ light 9●7 ishi 0
Fukusu (Japanese Journal of
Appl ied Physics) Vol1, 27
．． L209-210 (1988)]. In addition, a Tl-Ba-Ca-Cu10-based material was discovered that had a higher superconducting transition temperature than the Bi-based material. Z, Z.S.
heng and A. M. Hermann), Nature w-(Nature) Vol. 332,138-1
39 (1988). Ko. The details of the superconducting mechanism of this type of material are not clear, but the claw transition temperature may be higher than room temperature, and it is expected that it will have more promising properties as a high-temperature superconductor than conventional binary compounds. It was previously expected that a higher superconducting transition temperature could be achieved by alternately layering superconducting materials and insulators.
[M.H. Cohen and D.1.
D.H. Douglas, Jr. ) ,74shi1
Physical Re
View Letters) Vol, 19, 118-
121 (1967)].
発明が解決しようとする課題
しかしながｈ Ｔｌ−Ｂａ−Ｃａ−Ｃｕ−０系の材料
｛よ 現在の技術では主として焼結という過程でしか形
戒できないた取 セラミックの粉末あるいはブロックの
形状でしか得られなＬｓ −Ｘ この種の材料を実
用化する場念 薄膜状に加工することが強く要望されて
いるパ 従来の技術で１よ 良好な超電導特性を有する
薄膜作製は難しいものでありｔラ すなわ＆ Ｔｌ
−Ｂａ−Ｃａ−Ｃｕ−０系には超電導転移温度の異なる
いくつかの相が存在することが知られている爪 特に転
移温度がＩＯＯＫ以上の相を薄膜の形態で達或するの（
上 非常に困難とされていあまた 従来このＴｌ系にお
いて良好な超電導特性を示す薄膜を形或するためには少
なくとも６００℃以上の熱処理あるいは形或時の加熱が
必要であり、そのため高い超電導転移温度が期待される
絶縁展との周期的な積層構造を得ることは極めて困難と
考えられ またこの構造を利用した集積化デバイスを構
威することもたいへん困難であるとされていｔら
課題を解決するための手段
本発明者らによる第１の発明の酸化物超電導薄膜番上
主体成分が少なくともタリウム（Ｔｌ）、銅（Ｃｕ）
， およびアルカリ土類（ＩＩａ族）を含む層状酸化
物超電導薄膜と、主体成分が少なくともＢｉとタングス
テン（Ｗ）を含む層状酸化物薄膜が交互に積層された構
造を持つことを特徴とする酸化物超電導薄膜であも
さらに第２の発明の酸化物超電導薄膜の製造方法（九
基体上に 少なくともＴｌを含む酸化物と少なくとも銅
およびアルカリ土類（ＩＩａ族）を含む酸化物とを周期
的に積層させて形成する酸化物薄膜と、少なくともＢｉ
を含む酸化物と少なくともＷを含む酸化物を周期的に積
層させて形或する酸化物薄膜とを、さらに交互に積層さ
せて得ることを特徴とする酸化物超電導薄膜の製造方法
であもここでアルカリ土類（＆ＩＩａ族元素のうちの少
なくとも一種あるいは二種以上の元素を示す作用
本発明者らによる第１の発明においてｇ＆ＴｈＯ２酸化
膜層またはこれを−主体とした層によりともに覆われた
結晶構造となっているところのＴｌ系超電導薄膜と、Ｔ
ｌ系超電導体とその結晶における格子定数（ａ軸）がほ
ぼ等しく、また安定なＢｉｓ Ｑ ＊酸化膜層またはこ
れを主体とした層によりともに覆われた結晶構造となっ
ているところのＢｉとＷとを含む酸化物層状構造の絶縁
体薄膜とバ 交互に積層された構造をとることによって
、超電導膜と絶縁膜との間での相互拡散の少ない積層が
可能となり、その結果Ｔｌ系超電導薄膜における超電導
転移温度の上昇が実現されたものであも
さらに第２の発明においては上記構造を達或するた吹
少なくともＴｌを含む酸化惧 少なくともＢｉを含む酸
化物と、少なくとも銅およびアルカリ土類（ＩＩａ族）
を含む酸化物あるいは少なくともＷを含む酸化物とを、
周期的に積層させて分子レベルの制御による薄膜の作製
を行うことによって、再現性良＜Ｔｌ系超電導薄膜と絶
縁膜との積層を得ることに或功したものであも
実施例
以下に 本発明の実施例について図面を参照しながら説
明すも
ます 本発明者らはＴｌ系超電導薄膜と絶縁膜との周期
的な積層構造を実現するた△ Ｔ１系超電導薄膜と種々
の絶縁膜との相互作用について検討した
通焦Ｔｌ系超電導薄膜は４００〜６００℃に加熱した基
体上に蒸着して得も 蒸着抵 そのままでも薄膜は超電
導特性を示す力ｔ その後８５０〜９５０℃の熱処理を
施し 超電導特性を向上させもしかしなが転 基体温度
が高い時に絶縁膜をＴｌ系超電導薄膜に続いて積層した
り、絶縁膜を形或後熱処理を行った場合、超電導膜と絶
縁膜との間玄 元素の相互拡散が起こり超電導特性が太
きく劣化することが判明しｆ， 相互拡散を起こさな
いために（よ 超電導焦 絶縁膜の結晶性が優れている
こと、超電導膜・絶縁膜間での格子の整合性が優れてい
ること、絶縁膜が８５０〜９５０℃の熱処理に対して安
定であることが不可欠と考えられも種々の検討を行った
結莱 本発明者らＣ！ 少なくともＷを含むＢｉ酸化
物層状構造の薄膜が絶縁膜として適していることを見い
だした この理由として、Ｗを含むＢｉ層状酸化物（；
ｔ．Ｂｉａｓ２酸化物層がＷおよび酸素等の元素からな
る構造体を挟み込んだ層状ペロブス力イトを示すことが
知られており、このＢｉ＊０＊層は同種の結晶構造の物
質の界面に対して高温の熱処理においても非常に安定で
あり、またＴｌ系超電導体とＢｉ−Ｗ系酸化物との格子
の整合性がきわめて優れていることが考えられもさらに
本発明者らｉ；ｔ．．Ｔｌ系超電導薄膜とＢｉ−Ｗ系酸
化物薄膜を周期的に積層したＩＩ， Ｔｌ系超電導薄
膜本来の超電導転移温度が上昇することを見いだし氾
（実施例１）
本発明者らによる第ｌの発明の内容を更に深く理解され
るために 第１図を用い具体的な実施例を示す
第１図（友 本実施例で用いた二元マグネトロンスパッ
タ装置内部の概略図であり、 １１はＴｌ −Ｂａ−Ｃ
ａ−Ｃｕ−０ターゲット、 １２はＢｉ−Ｗ−０ターゲ
ット、 １３はシャッター、 １４はアパーチャコ １
５は基＆ １６は基体加熱用ヒーターを示す 焼結体
をブレス戒形加工して作製した２個のターゲットｌ１，
１２を用１，Ｘ．第１図に示すように配置させｔラすな
わ％ ＭｇＯ（１００）基体１５に焦点を結ぶように
各ターゲットが約３０゜傾いて設置されていもターゲッ
トの前方には回転するシャッター１３があり、その中に
設けられたアパーチャ−１４の回転をパルスモーターで
制御することにより， Ｔｌ−Ｂａ−Ｃａ−Ｃｕ−０
−＋ Ｂｉ−Ｗ−０−＋ ’ｒｌ−Ｂａ−Ｃａ−Ｃｕ−
０−＋ Ｂｉ−Ｗ−０−＋Ｔｌ−Ｂａ−Ｃａ−Ｃｕ−０
のサイクルでスバッタ蒸着が行なうことができ４ Ｔ
ｌ−Ｂａ−Ｃａ−Ｃｕ−０１１ Ｂｉ−Ｗ−０膜の積
層の様子を概念的に第２図に示す 第２図において、２
ｌはＴｌ−Ｂａ−Ｃａ−Ｃｕ−０風２ ２はＢｉ−Ｗ−
０膜を示す。Problems to be Solved by the InventionHowever, Tl-Ba-Ca-Cu-0 based materials can only be produced in the form of ceramic powder or blocks with current technology, mainly through the process of sintering. The opportunity to put this type of material into practical use is that it is strongly desired to process it into a thin film.It is difficult to fabricate a thin film with good superconducting properties using conventional techniques Sunawa & Tl
It is known that there are several phases with different superconducting transition temperatures in the -Ba-Ca-Cu-0 system.In particular, it is difficult to achieve a phase with a transition temperature higher than IOOK in the form of a thin film (
In addition, it has been considered extremely difficult to form a thin film that exhibits good superconducting properties in the Tl system, requiring heat treatment at at least 600°C or higher during forming, and therefore a high superconducting transition temperature. It is considered to be extremely difficult to obtain the expected periodic layered structure with insulation properties, and it is also considered to be extremely difficult to construct integrated devices using this structure. Means of oxide superconducting thin film according to the first invention by the present inventors
Main components are at least thallium (Tl) and copper (Cu)
, and an oxide having a structure in which layered oxide superconducting thin films containing alkaline earth elements (group IIa) and layered oxide thin films containing at least Bi and tungsten (W) as main components are laminated alternately. In addition to the superconducting thin film, the method for producing an oxide superconducting thin film of the second invention (9)
An oxide thin film formed by periodically stacking an oxide containing at least Tl and an oxide containing at least copper and alkaline earth (group IIa) on a substrate;
A method for producing an oxide superconducting thin film, characterized in that it is obtained by further alternately stacking an oxide containing W and an oxide thin film formed by periodically stacking an oxide containing at least W. In the first invention by the present inventors, crystals that are both covered with a g&ThO2 oxide film layer or a layer mainly composed of g&ThO2 The Tl-based superconducting thin film, which has a structure, and the Tl-based superconducting thin film
The lattice constants (a-axis) of the l-based superconductor and its crystal are almost the same, and the stable Bis By adopting an alternately laminated structure of insulator thin films with an oxide layered structure containing Even though an increase in the superconducting transition temperature has been achieved, the second invention further provides a method for achieving the above structure.
An oxide containing at least Tl, an oxide containing at least Bi, and at least copper and alkaline earth (group IIa)
or an oxide containing at least W,
By periodically laminating thin films and controlling them at the molecular level, we succeeded in obtaining a laminated layer of a Tl-based superconducting thin film and an insulating film with good reproducibility. An example of this will be explained with reference to the drawings. In order to realize a periodic stacked structure of a T1-based superconducting thin film and an insulating film, the present inventors investigated the interactions between the T1-based superconducting thin film and various insulating films. The focused Tl-based superconducting thin film studied can be deposited on a substrate heated to 400 to 600°C. However, if the substrate temperature is high, if an insulating film is laminated next to a Tl-based superconducting thin film, or if the insulating film is heat-treated after forming, interdiffusion of elements between the superconducting film and the insulating film will occur. It was found that this caused a significant deterioration of the superconducting properties.In order to prevent interdiffusion (superconducting focus) Although it is considered essential that the insulating film be stable against heat treatment at 850 to 950°C, the present inventors have conducted various studies to develop a Bi oxide layered structure containing at least W. We found that a thin film of Bi layered oxide containing W is suitable as an insulating film.
t. It is known that the Bias2 oxide layer exhibits a layered perovskite structure sandwiching a structure composed of elements such as W and oxygen, and this Bi*0* layer is exposed to high temperature at the interface of substances with the same crystal structure. It is considered that the lattice matching between the Tl-based superconductor and the Bi-W-based oxide is extremely stable, and that the lattice matching between the Tl-based superconductor and the Bi-W-based oxide is extremely excellent. ．． II, in which a Tl-based superconducting thin film and a Bi-W-based oxide thin film were periodically laminated, it was discovered that the superconducting transition temperature inherent to the Tl-based superconducting thin film increased (Example 1) First invention by the present inventors In order to understand the contents more deeply, FIG. 1 is used to show a specific example. -C
a-Cu-0 target, 12 is Bi-W-0 target, 13 is shutter, 14 is aperture 1
5 indicates the base & 16 indicates the heater for heating the base. Two targets l1 made by press-forming the sintered body,
12 using 1, X. Even though each target is installed at an angle of about 30 degrees so as to focus on the MgO (100) substrate 15, there is a rotating shutter 13 in front of the target. By controlling the rotation of the aperture 14 provided therein with a pulse motor, Tl-Ba-Ca-Cu-0
−+ Bi-W-0-+ 'rl-Ba-Ca-Cu-
0-+ Bi-W-0-+Tl-Ba-Ca-Cu-0
Spatter deposition can be performed with a cycle of 4 T.
Figure 2 conceptually shows how the l-Ba-Ca-Cu-011 Bi-W-0 film is stacked.
l is Tl-Ba-Ca-Cu-0 wind 2 2 is Bi-W-
0 film is shown.
ターゲット１１Ｓ １２への入力電九 Ｔｌ−Ｂａ−Ｃ
ａ−Ｃｕ−０およびＢｉ−Ｗ−０のスパッタ時間を制御
することにより、基体１５上に蒸着するＴｌ−Ｂａ−Ｃ
ａ−Ｃｕ−０膜２１， Ｂｉ−Ｗ−０膜２２の膜厚を
変えることができも基体ｌ５をヒーターｌ６で約６００
℃に加熱し アルゴン・酸素（１： １）混合雰囲気
０．５Ｐａのガス中で各ターゲットのスパッタリングを
行なう１，薄膜作製後は酸素雰囲気中において、８５０
℃の熱処理を１０分間施しｔ４ 本実施例で（よ 各
ターゲットノスパッタ電力を、Ｔｌ−Ｂａ−Ｃａ−Ｃｕ
−０： １００１， Ｂｉ−Ｗ−０： １００１とレ
ターゲット１１，１２のスパッタ時間を制御しｔ＝
Ｂｉ−Ｂａ−Ｃａ−Ｃｕ−０［２ １の元素の組或比
率がＴｌ：Ｂａ：Ｃａ：Ｃｕ＝２：２：２：３， Ｂｉ
−Ｗ−０膜２２の元素の組戊比率がＢｉ：Ｗ＝２：１に
なるよう、ターゲット１１．１２の元素の組戒比率を調
整し？，． Ｔｌ−Ｂａ−Ｃ８１−Ｃｕ−０膜２１を
Ｂｉ−Ｗ−０膜２２と積層せずに基体１５上に形成した
場振 すなわちＴｌ−Ｂａ−Ｃａ−Ｃｕ−０膜２１その
ものの特性ｉ；ｔ． １２５Ｋで超電導転移を起こし
１００Ｋで抵抗がゼロになるものであう丸 さらに本発
明者らによるａ 結晶性を維持したまま、薄くできる膜
厚の限界はＢｉ−Ｗ−０膜２２については約２００Ａで
あっム 絶縁膜はできるだけ薄い方が好ましいの玄 膜
厚２００ＡのＢｉ−Ｗ−０膜２２に対して、Ｔｌ−Ｂａ
−Ｃａ−Ｃｕ−０膜２１の膜厚を変え第２図に示すよう
な（Ｔｌ−Ｂａ−Ｃａ−Ｃｕ−０膜→Ｂｉ−Ｗ−０膜）
の積層構造を２０周期作製し九 そのときの超電導薄膜
の抵抗の温度特性を第３図に示す 第３図において、Ｔ
ｌ−Ｂａ−Ｃａ−Ｃｕ−０膜２１の膜厚がＩＯＯＡ，
３００Ａ， ５００Ａのときのを特性をそれぞ札
特性３１，３２、 ３３に示す 特性３ｌにおいてはゼ
ロ抵抗温度が約３０ＫとＴｌ−Ｂａ−Ｃａ−Ｃｕ−０膜
２１の特性が劣化することがわかッｆ−ｏ この理由
として、Ｔｌ−Ｂａ−Ｃａ−Ｃｕ−０膜２１とＢｉ−Ｗ
−０膜２２との間で元素の相互拡散による膜２１，２２
の結晶性の破壊が考えられも さらに特性３３において
ＬＬ Ｂｉ−Ｗ−０膜２２との周期的な積層なしに基
体ｌ５上につけたときのＴｌ−Ｂａ−Ｃａ−Ｃｕ−０膜
２１本来の超電導特性とほとんど同じであり、絶縁膜Ｂ
ｉ−Ｗ−０膜２２との積層効果は確認されなかっｔ４シ
かしなが板 本発明者らは特性３２において、超電導転
移温嵐 ゼロ抵抗温度がともに約５Ｋ上昇することを見
いだした この効果の詳細な理由については未だ不明で
あるＩＪ＜． Ｔｌ−Ｂａ−Ｃａ−Ｃｕ−０膜２１と
Ｂｉ−Ｗ−０膜２２との積層界面での元素の相互拡散の
影響が少なく、かつ薄いＢｉ −Ｗ−０１ｌ２２を介し
て複数のＴｌ−Ｂａ−Ｃａ−Ｃｕ−０膜２ｌを積層する
ことによりＴｌ−Ｂａ−Ｃａ−Ｃｕ−０膜２■において
超電導機構になんらかの変化が引き起こされたことが考
えられも
な叙 超電導転移温度が上昇する効果！Ｌ Ｔｌ−Ｂ
ａ−Ｃａ−Ｃｕ−０膜２ｌの膜厚が２００〜４００Ａの
範囲で有効であることを、本発明者らは確認しｆ，な叙
本発明者らは薄膜形成後の熱処理において、Ｔｌガス
を供給しながら行うと、より再現性よく超電導特性が得
られることを見いだし１， このことはＴｌの蒸気圧
が異常に高く、蒸発しやすいのでこれを供給することに
よって、結晶性の劣化を防ぐことができたためと考えら
れも
な耘 本発明者らはターゲットｌ １， もしくはｌ
２に鉛（Ｐｂ）を添加してスパッタしたとき、基体ｌ５
の温度が上記実施例よりも約１００℃低くて転上記実施
例と同等な結果が得られることを見いだし九
さらに本発明者ら｛ＩＴｌの酸化物と、ＢＬＣａ．
Ｃｕの酸化物を異なる蒸発源から真空中で別々ニ蒸発さ
せ、基体上にＴｌ−０４ Ｂａ−Ｃｕ−０−ｅ Ｃａ−
Ｃｕ−０−＋Ｂａ−Ｃｕ−０→Ｔｌ−０の順で周期的に
積層させた場念さらにＢｉの酸化物と、Ｗの酸化物を異
なる蒸発源から真空中で別々に蒸発させ、Ｂｉ−０→Ｗ
−０−ｈＢｉ−０の順で周期的に積層させた場合、 （
実施例ｌ）に示した積層構造作製方法より極めて制御性
良く、安定した膜質へ しかも膜表面が極めて平坦なＴ
ｌ−Ｂａ−Ｃａ−Ｃｕ−０超電導薄膜およびＢｉ−Ｗ−
０絶縁膜が得られることを見いだしｔも
さらに本発明者ら（＆ Ｔｌ−０、Ｂａ−Ｃｕ−０、
Ｃａ−Ｃｕ−０，Ｂｉ−０， Ｗ−０を別々の蒸発源か
ら蒸発させ、Ｔｌ−Ｂａ−Ｃａ−Ｃｕ−０超電導薄膜と
Ｂｉ−Ｗ−０絶縁膜を周期的に積層した線 極めて制御
性良＜ ｍ （Ｔｌ−Ｂａ−Ｃａ−Ｃｕ−０）ｎ （
Ｂｉ−Ｗ−０）の周期構造を持つ薄膜を形戒できること
を見いだし１， ここでれ ｎは正の整数を示す さ
らに このｍ （Ｔｌ−Ｂａ−Ｃａ−Ｃｕ−０） ・
ｎ （Ｂｉ−Ｗ−０）薄膜ｇ！ ＜実施例１）に示し
たＴｌ−Ｂａ−Ｃａ−Ｃｕ一〇を同時に蒸着して得る超
電導薄膜Ｌ Ｂｉ−Ｗ−０を同時に蒸着して得る酸化
物絶縁膜とを周期的に積層して得た薄膜に比べて、はる
かに結晶性が優れ超電導転移温嵐 臨界電流密度等の特
性に勝っているζとも併せて見いだし丸 さらに本発明
者らＣ友 上記の方法で作製したＴｌ−Ｂａ−Ｃａ−
Ｃｕ−０超電導薄膜とＢｉ−Ｗ−０絶縁膜はともに薄膜
表面が極めて平坦であることを見いだし九
これらのことは第４図に示す積層の概念図を用いて説明
することができも すなわ板 それぞれ層状構造を構戒
する異なる元素を別々に順次積層していくことにより、
基体表面に対し平行な面内だけで積層された蒸着元素が
動くだけ℃ 基体表面に対し垂直方向への元素の移動が
ないことによるものと考えられも さら４Ｑ Ｂｉと
Ｗを含む酸化物層状ペロプス力イト構造の結晶のａ軸の
長さ＆友Ｔｌ−Ｂａ−Ｃａ−Ｃｕ−０のそれとほぼ等し
く、゜連続的にエビタキシャル戒長が可能であることに
よるものと考えられも
さらに以外にＬ 良好な超電導特性を得るに必要な基体
の温嵐 熱処理温度ｋ 従来より低いことを見いだしｔ
も
Ｔｌ −０， Ｂａ−Ｃｕ−０， Ｃａ−Ｃｕ−０，
， Ｂｉ−０， Ｗ−０を周期的に積層させる方法とし
ては いくつか考えられも −般＋，：，ＭＢＥ装置あ
るいは多元のＥＢ蒸着装置で蒸発源の前を開閉シャッタ
ーで制御したり、気相戒長法で作製する際にガスの種類
を切り替えたりすることにより、周期的積層を達或する
ことができも しかしこの種の非常に薄い層の積層には
従来スパッタリング蒸着は不向きとされてい九 この理
由（よ 或膜中のガス圧の高さに起因する不純物の混入
およびエネルギーの高い粒子によるダメージと考えられ
ていも しかしなか板 本発明者らＥ上 このＴｌ系
酸化物超電導体に対してスパッタリングにより異なる薄
い層の積層を行なったとこム 以外にも良好な積層膜作
製が可能なことを発見しｔ４ スパッタ中の高い酸素
ガス圧およびスパッタ放電ＭＴｌ系のＩＯＯＫ以上の臨
界温度を持っ相の形恵 およびＢｉ−Ｗ−０絶縁膜の形
成に都合がよいためではなかろうかと考えられも
スパッタ蒸着で異なる物質を積層させる方法として｛上
組成分布を設けたｌケのスパッタリングターゲットの
放電位置を周期的に制御するという方法がある爪 組戒
の異なる複数個のターゲットのスパッタリングという方
法を用いると比較的簡単に達或することができも この
場伍 複数個のターゲットの各々のスパッタ量を周期的
に制御したり、あるいはターゲットの前にシャッターを
設けて周期的に開閉したりして、周期的積層膜を作製す
ることができも また基板を周期的運動させて各々ター
ゲットの上を移動させる方法でも作製が可能であも レ
ーザースパッタあるいはイオンビームスパッタを用いた
場合に《戴 複数個のターゲットを周期運動させてビー
ムの照射するターゲットを周期的に変えれば 周期的積
層膜が実現されも このように複数個のターゲットを用
いたスパッタリングにより比較的簡単にＴｌ系酸化物の
周期的積層が作製可能となん
以下本発明者らによる第２の発明の内容をさらに深く理
解されるために 具体的な実施例を示す（実施例２）
第５図に本実施例で用いた５元マグネトロンスパッタ装
置の概略図を示す 第５図において、 ５０はＢｉター
ゲット、 ５１はＴｌターゲット、 ５２はＢａＣｕ合
金ターゲット、 ５３はＣａＣｕ合金ターゲット、 ５
４はＷターゲット、 ５５はシャッター、５６はスリッ
ト、 ５７は基依 ５８は基体加熱用ヒーターを示す
計５個のターゲット５０、 ５１、５２、 ５３、 ５
４は第２図に示すように配置させた 即Ｌ ＭｇＯ
（１ ０ ０）基体５７に焦点を結ぶように各ターゲッ
トが約３０”傾いて設置されていも ターゲットの前方
には回転するシャッター５５があり、パルスモー夕で駆
動することによりその中に設けられたスリット５６の回
転が制御され 各ターゲットのサイクル及びスパッタ時
間を設定することができも 基体５７をヒーター５８で
約６００℃に加熱し アルゴン・酸素（５： １）混
合雰囲気３Ｐａのガス中で各ターゲットのスパッタリン
グを行なっｆ， 各ターゲットのスパッタ電流を、Ｂ
ｉ ： ３０ｍＡ， Ｔｌ ： ３０ｍＡ， ＢａＣｕ
： ８０ｍＡ， ＣａＣｕ ： ３００ｍＡ，Ｗ：４
００ｍＡにして実験を行ッｆ，， Ｔｌ−ＢａＣｕ−
ＣａＣｕ−”ＴｌのサイクルでスパッタＬＡＴｌ−Ｂａ
−Ｃａ−Ｃｕ−０膜の元素の組或比率がＴｌ：Ｂａ：Ｃ
ａ：Ｃｕ−２：２：２：３となるように各ターゲットの
スパッタ時間を調整し上記サイクルを２０周期行った結
凰 １００Ｋ以上の臨界温度を持つ相を作製することが
でき氾このままの状態でもこのＴｌ−Ｂａ−Ｃａ−Ｃｕ
−０薄膜は１００Ｋ以上の超電導転移を示した力ｔ さ
らに酸素中で６５０ｔ．１時間の熱処理を行なうと非常
に再現性よくなり、超電導転移温度は１２５運 抵抗が
ゼロになる温度は１０５Ｋになうｔも 超電導転移温
度が１００Ｋを越す相は金属元素がＴｌ−Ｂａ−Ｃｕ−
Ｃａ−Ｃｕ−Ｃａ−Ｃｕ−Ｂａ−Ｔｌの順序で並んだ酸
化物の層から戊り立っているとも言われており、本発明
の製造方法がこの構造−を作るのに非常に役だっている
のではないかと考えられも また 同様にＢｉ→ｌ−＋
ＢｉのサイクルでＢｉ−Ｗ−０膜の元素の組或比がＢｉ
：Ｗ−２：ｌとなるように各ターゲットのスパッタ時間
を調整し 上記サイクルを４サイクルまで少なくして、
Ｂｉ−Ｗ−０膜の膜厚を薄くしてｋ 極めて結晶性に優
れたＢｉ−Ｗ−０膜が得られん
さらに本発明者らはｍｘ （Ｔｌ−ｅＢａｃｕ−＊Ｃａ
Ｃｕ−＋ＢａＣｕ−＋Ｔｌ） →ｎ ｘ （Ｂｉ−ｓ＝
Ｗ−＋Ｂｉ）のサイクルで各ターゲットをスパッタＬ，
， ｍ （Ｔｌ−Ｂａ−Ｃａ−Ｃｕ−０） ・ｎ（
Ｂｉ−Ｗ−０）薄膜を基体５７上に作製した ここで鶏
ｎは正の整数を示す 本発明者らはｎ＝４のとき、ｍ
を変化させて周期的に積層して得た膜の超電導特性を調
べん 第６図にｍ＝２、６、 ｌ６のときに得た膜の抵
抗の温度変化をそれぞれ特性６１，６２、６３に示す
第６図において、ｍ＝６のとき、最も高い超電導転移温
度およびゼロ抵抗温嵐 すなわち特性６２が得られ丸
特性６２の超電導転移温嵐 ゼロ抵抗温度はＴｌ−Ｂａ
−Ｃａ−Ｃｕ−０膜本来のそれらの値よりも約８Ｋ高い
ものであっ九この効果の詳細な理由については未だ不明
である戟 本実施例に示した方法でＴｌ−Ｂａ−Ｃａ−
Ｃｕ−０膜とＢｉ−Ｗ−０膜とを周期的に積層すること
によって、Ｔｌ−Ｂａ−Ｃａ−Ｃｕ−０膜とＢｉ−Ｗ−
０膜が互いにＴ１＊０象層と１３ｉ象Ｑ＊層を介してエ
ビタキシャル戒長していることにより積層界面での元素
の相互拡散の影響がなく、かつ結晶性に優れた薄いＢｉ
−Ｗ−０膜を介して同じく結晶性に優れたＴｌ−Ｂａ−
Ｃａ−Ｃｕ−０１１［を積層することによりＴｌ−Ｂａ
−Ｃａ−Ｃｕ−０膜において超電導機構になんらかの変
化が引き起こされたことが考えられもな叙 超電導転移
温度が上昇する効果ｓｔ， Ｔｌ→ＢａＣｕ−ｅ Ｃ
ａＣｕ−＋ ＢａＣｕ−＊ Ｔｌのサイクルが４〜ｌＯ
の範囲で有効であることを、本発明者らは確認したさら
に 本発明者らは基体の温度は４００〜６００℃．の範
囲で最もＴｌ−Ｂａ−Ｃａ−Ｃｕ−０超電導薄膜の結ｉ
ａおよび超電導特性がよいことを見いだし九 これは蒸
気圧が異常にに高いＴｌの蒸発が６００℃以上で起こり
、さらに４００℃以下では結晶化が得られないことが考
えられも
な叙 本発明者らはターゲット５ １， もしくは５
４に鉛（ Ｐ ｂ）を添加してスパッタしたとき、基体
５７の温度が上記実施例よりも約１００℃低くて転上記
実施例と同等な結果が得られることを見いだしｔ４
発明の効果
以上のように第１の本発明の酸化物超電導薄膜ｊよＴｌ
系酸化物超電導薄膜の超電導転移温度を上昇させる構造
を提供するものであり、第２の発明の酸化物超電導薄膜
の製造方法は第１の発明をより効果的に実現し デバイ
ス等の応用には必須の低温でのプロセス確立したもので
あり、本発明の工業的価値は太きもちInput power to target 11S 12 Tl-Ba-C
Tl-Ba-C deposited on the substrate 15 by controlling the sputtering time of a-Cu-0 and Bi-W-0.
Although the film thicknesses of the a-Cu-0 film 21 and the Bi-W-0 film 22 can be changed, the substrate 15 is heated to about 600 ml by using the heater 16.
℃ and sputtering each target in a mixed atmosphere of argon and oxygen (1:1) at 0.5 Pa.
In this example, the sputtering power for each target was changed to Tl-Ba-Ca-Cu.
-0: 1001, Bi-W-0: 1001, and controlling the sputtering time of targets 11 and 12, t=
Bi-Ba-Ca-Cu-0[2 The ratio of elements in 1 is Tl:Ba:Ca:Cu=2:2:2:3, Bi
-Adjust the element ratio of target 11.12 so that the element ratio of W-0 film 22 becomes Bi:W=2:1? 、． Field vibration when the Tl-Ba-C81-Cu-0 film 21 is formed on the substrate 15 without being laminated with the Bi-W-0 film 22, that is, the characteristics i; t of the Tl-Ba-Ca-Cu-0 film 21 itself. ．． The circle indicates that a superconducting transition occurs at 125K and the resistance becomes zero at 100K.Furthermore, the limit of the film thickness that can be made thin while maintaining crystallinity is approximately 200A for the Bi-W-0 film 22. It is preferable that the insulating film be as thin as possible.For the Bi-W-0 film 22 with a film thickness of 200A,
-The film thickness of the Ca-Cu-0 film 21 is changed as shown in FIG. 2 (Tl-Ba-Ca-Cu-0 film → Bi-W-0 film).
The temperature characteristics of the resistance of the superconducting thin film at that time are shown in Figure 3. In Figure 3, T
The thickness of the l-Ba-Ca-Cu-0 film 21 is IOOA,
The characteristics at 300A and 500A are shown respectively.
It can be seen that in characteristic 3l shown in characteristics 31, 32, and 33, the zero resistance temperature is about 30 K, and the characteristics of the Tl-Ba-Ca-Cu-0 film 21 deteriorate. Ca-Cu-0 film 21 and Bi-W
-0 film 22 due to interdiffusion of elements between the films 21 and 22
Further, in characteristic 33, the original superconductivity of the Tl-Ba-Ca-Cu-0 film 21 when deposited on the substrate 15 without periodic lamination with the LL Bi-W-0 film 22 is considered. The characteristics are almost the same as those of insulating film B.
No stacking effect with the i-W-0 film 22 was confirmed.The inventors found that in characteristic 32, the superconducting transition temperature storm and zero resistance temperature both increased by approximately 5K.This effect The detailed reason for IJ<. is still unknown. The effect of mutual diffusion of elements at the laminated interface between the Tl-Ba-Ca-Cu-0 film 21 and the Bi-W-0 film 22 is small, and multiple Tl-Ba- It is inconceivable that some change was caused in the superconducting mechanism in the Tl-Ba-Ca-Cu-0 film 2 by stacking the Ca-Cu-0 film 2l.The effect of increasing the superconducting transition temperature! L Tl-B
The present inventors have confirmed that the film thickness of 2L of a-Ca-Cu-0 film is effective in the range of 200 to 400A. They found that superconducting properties can be obtained with better reproducibility by supplying Tl while supplying it.1 This means that the vapor pressure of Tl is abnormally high and it evaporates easily, so by supplying Tl, the deterioration of crystallinity can be prevented. This is unlikely to be because the inventors were able to target l 1 or l
When lead (Pb) is added to 2 and sputtered, the base l5
The present inventors found that the temperature of BLCa.
The oxides of Cu were evaporated separately in vacuum from different evaporation sources, and Tl-04 Ba-Cu-0-e Ca-
In addition, Bi oxide and W oxide were evaporated separately in vacuum from different evaporation sources, and Bi- 0→W
When stacked periodically in the order of -0-hBi-0, (
The layered structure fabrication method shown in Example 1) has much better controllability and stable film quality. Moreover, the film surface is extremely flat.
l-Ba-Ca-Cu-0 superconducting thin film and Bi-W-
The present inventors further discovered that an insulating film of
A line in which Ca-Cu-0, Bi-0, and W-0 are evaporated from separate evaporation sources, and Tl-Ba-Ca-Cu-0 superconducting thin films and Bi-W-0 insulating films are periodically laminated. Good quality < m (Tl-Ba-Ca-Cu-0)n (
We found that it is possible to form a thin film with a periodic structure of Bi-W-0)1, where n is a positive integer, and m (Tl-Ba-Ca-Cu-0) ・
n (Bi-W-0) thin film g! A superconducting thin film L obtained by simultaneously depositing Tl-Ba-Ca-Cu10 shown in <Example 1) and an oxide insulating film obtained by simultaneously depositing Bi-W-0 are periodically laminated. In addition, the Tl-Ba-Ca film prepared by the above method was found to have much superior crystallinity and superior properties such as superconducting transition temperature and critical current density compared to thin films made by the present inventors. −
It was found that both the Cu-0 superconducting thin film and the Bi-W-0 insulating film have extremely flat thin film surfaces9.These can be explained using the conceptual diagram of the lamination shown in Figure 4. By sequentially stacking different elements, each with a layered structure,
This is thought to be due to the fact that the stacked evaporated elements move only in the plane parallel to the substrate surface, and there is no movement of the elements in the direction perpendicular to the substrate surface. The length of the a-axis of the crystal with the vitreous structure is almost equal to that of Tl-Ba-Ca-Cu-0, and it is thought that this is due to the fact that continuous ebitaxial length is possible. The heat treatment temperature of the substrate necessary to obtain good superconducting properties was found to be lower than that of conventional methods.
Also Tl -0, Ba-Cu-0, Ca-Cu-0,
, Bi-0, and W-0 can be stacked periodically. There are several possible methods for periodically stacking , Bi-0, and W-0. Although it is possible to achieve periodic stacking by switching the type of gas during fabrication using the phase-cut method, sputtering deposition has traditionally been considered unsuitable for this type of stacking of extremely thin layers. (9) The reason for this (although it is thought that the contamination of impurities due to the high gas pressure in the film and the damage caused by high-energy particles) is the reason for this. By using sputtering to stack different thin layers, we discovered that it was possible to fabricate a good stacked film in addition to t4. This may be because it is convenient for forming a Bi-W-0 insulating film and a Bi-W-0 insulating film. This can be achieved relatively easily by using a method of sputtering multiple targets with different combinations, but in this case, the amount of sputtering for each of multiple targets can be controlled periodically. It is possible to fabricate a periodic stacked film by controlling the target structure, or by providing a shutter in front of the target and opening and closing it periodically.Also, by periodically moving the substrate and moving it over each target. However, if laser sputtering or ion beam sputtering is used, periodic laminated films can be realized by periodically moving multiple targets and periodically changing the targets irradiated with the beam. In order to further understand the content of the second invention by the present inventors, the following is a detailed description of the invention. (Example 2) Fig. 5 shows a schematic diagram of the five-element magnetron sputtering apparatus used in this example. In Fig. 5, 50 is a Bi target, 51 is a Tl target, and 52 is a BaCu alloy target. , 53 is a CaCu alloy target, 5
4 is a W target, 55 is a shutter, 56 is a slit, 57 is a base, and 58 is a heater for heating the substrate.
Total of 5 targets 50, 51, 52, 53, 5
4 is arranged as shown in Figure 2.Immediate L MgO
(1 0 0) Even if each target is installed at an angle of about 30" so as to focus on the base 57, there is a rotating shutter 55 in front of the target, and the shutter 55 is driven by a pulse motor. The rotation of the slit 56 is controlled, and the cycle and sputtering time for each target can be set.The substrate 57 is heated to about 600°C with a heater 58, and each target is heated in a mixed atmosphere of argon and oxygen (5:1) at 3 Pa. sputtering is performed, f, and the sputtering current of each target is B
i: 30mA, Tl: 30mA, BaCu
: 80mA, CaCu : 300mA, W: 4
Conduct the experiment at 00 mA f,, Tl-BaCu-
Sputtered LATl-Ba with cycle of CaCu-"Tl
-The composition ratio of elements of the Ca-Cu-0 film is Tl:Ba:C
a: Cu-2: The sputtering time of each target was adjusted so that the ratio was 2:2:3, and the above cycle was repeated 20 times.A phase with a critical temperature of 100K or more could be created. But this Tl-Ba-Ca-Cu
-0 thin film showed a superconducting transition at a force of 100K or more. After 1 hour of heat treatment, the reproducibility becomes very good, and the superconducting transition temperature is 125 K. The temperature at which the resistance becomes zero is 105 K. The phase where the superconducting transition temperature exceeds 100 K has a metallic element of Tl-Ba-Cu. −
It is said that the structure is formed by an oxide layer arranged in the order Ca-Cu-Ca-Cu-Ba-Tl, and the manufacturing method of the present invention is extremely useful in creating this structure. Similarly, Bi→l−+
In the Bi cycle, the element composition ratio of the Bi-W-0 film changes to Bi
:W-2:l by adjusting the sputtering time for each target and reducing the above cycles to 4 cycles.
By reducing the thickness of the Bi-W-0 film, a Bi-W-0 film with extremely excellent crystallinity cannot be obtained.
Cu-+BaCu-+Tl) →n x (Bi-s=
Sputter each target with a cycle of W−+Bi) L,
, m (Tl-Ba-Ca-Cu-0) ・n(
Bi-W-0) thin film was fabricated on the substrate 57, where n is a positive integer.
We will investigate the superconducting properties of films obtained by periodically stacking them with different values. Figure 6 shows the temperature changes in resistance of films obtained when m = 2, 6, and l6, with characteristics 61, 62, and 63, respectively. show
In Fig. 6, when m = 6, the highest superconducting transition temperature and zero resistance temperature storm, that is, characteristic 62, are obtained and the circle is rounded.
Characteristic 62 superconducting transition temperature storm Zero resistance temperature is Tl-Ba
-Ca-Cu-0 film is about 8K higher than the original value.The detailed reason for this effect is still unknown.Tl-Ba-Ca-
By periodically stacking Cu-0 film and Bi-W-0 film, Tl-Ba-Ca-Cu-0 film and Bi-W-
Since the 0 films are ebitaxially extended to each other via the T1*0 and 13i quadrant Q* layers, there is no effect of interdiffusion of elements at the lamination interface, and the thin Bi layer has excellent crystallinity.
-Tl-Ba- which also has excellent crystallinity through the W-0 film
By laminating Ca-Cu-011[Tl-Ba
-The effect of increasing the superconducting transition temperature st, Tl→BaCu-e C
aCu-+ BaCu-* Tl cycle is 4~1O
The present inventors have confirmed that the temperature of the substrate is 400 to 600°C. The highest concentration of Tl-Ba-Ca-Cu-0 superconducting thin film in the range of
This is because Tl, which has an abnormally high vapor pressure, evaporates at temperatures above 600°C and cannot be crystallized below 400°C. are targets 5 1 or 5
It was found that when lead (Pb) was added to 4 and sputtered, the temperature of the substrate 57 was about 100°C lower than in the above embodiment, and results equivalent to those in the above embodiment were obtained. As shown in the first oxide superconducting thin film of the present invention, Tl
The present invention provides a structure for increasing the superconducting transition temperature of an oxide superconducting thin film, and the method for producing an oxide superconducting thin film of the second invention more effectively realizes the first invention and is suitable for applications such as devices. The essential low-temperature process has been established, and the industrial value of the present invention is significant.
第１図は第１の発明の一実施例における薄膜の製造装置
の概略構造阻 第２図はＭ１の発明の薄展の構造阻 第
３図は第１図の装置により得た薄膜における抵抗の温度
特性阻 第４図は第２の発明の構造飄 第５図は第２の
発明の実施例における薄膜の製造装置の概略構造阻 第
６図は第５図の装置により得た薄膜における抵抗の温度
特性図であも
１１、１２、５０．５Ｌ５２、５３、５４−−−−ス八
”ｙ？ｌＪ７？”夕−＆”ｙ｝、１３、５５・・・シャ
ッター、゛ｌ４・・・ア八１−チャー、５６・・・スリ
フト、ｌ５、５７・・・ＭｇＯ基．体、ｌ６、５８−−
−ｈ−ター、２１ ・・４１−Ｂａ−Ｃａ−Ｃｕ−０膜
、２２・・・Ｂｉ−１−０１１、３１、３２、３３、６
１、６２、６３・・・薄膜の抵抗の温度特也FIG. 1 shows a schematic structure of a thin film manufacturing apparatus according to an embodiment of the first invention; FIG. 2 shows a structure of a thin film according to M1's invention; and FIG. 3 shows the resistance of a thin film obtained by the apparatus of FIG. Figure 4 shows the structure of the second invention. Figure 5 shows the schematic structure of the thin film manufacturing apparatus according to the embodiment of the second invention. Figure 6 shows the resistance of the thin film obtained by the apparatus of Figure 5. In the temperature characteristic diagram, 11, 12, 50.5L52, 53, 54--S8"y?lJ7?"Y-&"y}, 13, 55...Shutter, ゛l4...A 81-char, 56...thrift, l5, 57...MgO base body, l6, 58--
-h-tar, 21...41-Ba-Ca-Cu-0 film, 22...Bi-1-011, 31, 32, 33, 6
1, 62, 63...Temperature characteristics of thin film resistance
Claims (5)
Ｃｕ）、およびアルカリ土類（ I I ａ族）を含む層状
酸化物超電導薄膜と、主体成分が少なくともＴｌとタン
グステン（Ｗ）を含む層状酸化物薄膜が交互に積層され
た構造を持つ（ここでアルカリ土類は、 I I ａ族元素
のうちの少なくとも一種あるいは二種以上の元素を示す
。）ことを特徴とする酸化物超電導薄膜。(1) The main components are at least thallium (Tl) and copper (
It has a structure in which layered oxide superconducting thin films containing Cu) and alkaline earth elements (group IIa) and layered oxide thin films containing at least Tl and tungsten (W) as main components are laminated alternately. 1. An oxide superconducting thin film characterized in that earth represents at least one or two or more elements of Group IIa elements.
くとも銅およびアルカリ土類（ I I ａ族）を含む酸化
物とを周期的に積層させて形成する酸化物薄膜と、少な
くともＢｉを含む酸化物と少なくともＷを含む酸化物を
周期的に積層させて形成する酸化物薄膜とを、交互に積
層させて得る（ここでアルカリ土類は、 I I ａ族元素
のうちの少なくとも一種あるいは二種以上の元素を示す
。）ことを特徴とする酸化物超電導薄膜の製造方法。(2) An oxide thin film formed by periodically stacking an oxide containing at least Tl and an oxide containing at least copper and alkaline earth (group IIa) on a substrate, and an oxide containing at least Bi. and oxide thin films formed by periodically stacking oxides containing at least W (here, the alkaline earth is at least one or two or more of the group IIa elements). A method for producing an oxide superconducting thin film, characterized in that:
とを特徴とする請求項２記載の酸化物超電導薄膜の製造
方法。(3) The method for producing an oxide superconducting thin film according to claim 2, characterized in that the temperature of the substrate is in the range of 400 to 600°C.
で行うことを特徴とする請求項２記載の酸化物超電導薄
膜の製造方法。(4) The method for producing an oxide superconducting thin film according to claim 2, wherein the evaporation of the laminated material is performed using at least two types of evaporation sources.
を特徴とする請求項２記載の酸化物超電導薄膜の製造方
法。(5) The method for producing an oxide superconducting thin film according to claim 2, wherein the evaporation of the laminated material is performed by sputtering.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP1229917A JPH0714817B2 (en) | 1989-09-05 | 1989-09-05 | Oxide superconducting thin film and method for producing the same |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP1229917A JPH0714817B2 (en) | 1989-09-05 | 1989-09-05 | Oxide superconducting thin film and method for producing the same |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH0393625A true JPH0393625A (en) | 1991-04-18 |
| JPH0714817B2 JPH0714817B2 (en) | 1995-02-22 |
Family
ID=16899765
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP1229917A Expired - Lifetime JPH0714817B2 (en) | 1989-09-05 | 1989-09-05 | Oxide superconducting thin film and method for producing the same |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH0714817B2 (en) |
-
1989
- 1989-09-05 JP JP1229917A patent/JPH0714817B2/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| JPH0714817B2 (en) | 1995-02-22 |
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