JPH02296730A - Manufacture of thin film superconductor - Google Patents
Manufacture of thin film superconductorInfo
- Publication number
- JPH02296730A JPH02296730A JP1118971A JP11897189A JPH02296730A JP H02296730 A JPH02296730 A JP H02296730A JP 1118971 A JP1118971 A JP 1118971A JP 11897189 A JP11897189 A JP 11897189A JP H02296730 A JPH02296730 A JP H02296730A
- Authority
- JP
- Japan
- Prior art keywords
- thin film
- strontium
- oxide
- calcium
- substrate
- 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 31
- 239000002887 superconductor Substances 0.000 title claims abstract description 21
- 238000004519 manufacturing process Methods 0.000 title claims description 13
- 229910052712 strontium Inorganic materials 0.000 claims abstract description 31
- 229910052791 calcium Inorganic materials 0.000 claims abstract description 29
- 238000004544 sputter deposition Methods 0.000 claims abstract description 17
- 239000000758 substrate Substances 0.000 claims abstract description 17
- 229910052797 bismuth Inorganic materials 0.000 claims abstract description 6
- 229910052802 copper Inorganic materials 0.000 claims abstract description 5
- 239000011575 calcium Substances 0.000 claims description 31
- CIOAGBVUUVVLOB-UHFFFAOYSA-N strontium atom Chemical compound [Sr] CIOAGBVUUVVLOB-UHFFFAOYSA-N 0.000 claims description 29
- OYPRJOBELJOOCE-UHFFFAOYSA-N Calcium Chemical compound [Ca] OYPRJOBELJOOCE-UHFFFAOYSA-N 0.000 claims description 25
- 238000000034 method Methods 0.000 claims description 14
- 239000010949 copper Substances 0.000 claims description 10
- JCXGWMGPZLAOME-UHFFFAOYSA-N bismuth atom Chemical compound [Bi] JCXGWMGPZLAOME-UHFFFAOYSA-N 0.000 claims description 6
- 239000000203 mixture Substances 0.000 claims description 6
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 claims description 4
- 230000008020 evaporation Effects 0.000 claims description 4
- 238000001704 evaporation Methods 0.000 claims description 4
- IATRAKWUXMZMIY-UHFFFAOYSA-N strontium oxide Chemical compound [O-2].[Sr+2] IATRAKWUXMZMIY-UHFFFAOYSA-N 0.000 claims 4
- BRPQOXSCLDDYGP-UHFFFAOYSA-N calcium oxide Chemical compound [O-2].[Ca+2] BRPQOXSCLDDYGP-UHFFFAOYSA-N 0.000 claims 2
- ODINCKMPIJJUCX-UHFFFAOYSA-N calcium oxide Inorganic materials [Ca]=O ODINCKMPIJJUCX-UHFFFAOYSA-N 0.000 claims 2
- 239000000292 calcium oxide Substances 0.000 claims 2
- 239000002648 laminated material Substances 0.000 claims 2
- 238000010030 laminating Methods 0.000 abstract description 2
- 239000010410 layer Substances 0.000 description 12
- 229910045601 alloy Inorganic materials 0.000 description 9
- 239000000956 alloy Substances 0.000 description 9
- 239000012071 phase Substances 0.000 description 9
- 239000013078 crystal Substances 0.000 description 8
- 230000000737 periodic effect Effects 0.000 description 8
- 239000000463 material Substances 0.000 description 7
- 238000001228 spectrum Methods 0.000 description 6
- 239000010408 film Substances 0.000 description 5
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 description 4
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 4
- 239000001301 oxygen Substances 0.000 description 4
- 229910052760 oxygen Inorganic materials 0.000 description 4
- 230000015572 biosynthetic process Effects 0.000 description 3
- 150000001875 compounds Chemical class 0.000 description 3
- 238000009792 diffusion process Methods 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- 238000010438 heat treatment Methods 0.000 description 3
- 238000003475 lamination Methods 0.000 description 3
- 238000007740 vapor deposition Methods 0.000 description 3
- 229910000882 Ca alloy Inorganic materials 0.000 description 2
- 101150027751 Casr gene Proteins 0.000 description 2
- 229910000750 Niobium-germanium Inorganic materials 0.000 description 2
- 229910001278 Sr alloy Inorganic materials 0.000 description 2
- 238000002441 X-ray diffraction Methods 0.000 description 2
- 229910052786 argon Inorganic materials 0.000 description 2
- 239000000919 ceramic Substances 0.000 description 2
- 238000007796 conventional method Methods 0.000 description 2
- 230000007423 decrease Effects 0.000 description 2
- 238000002265 electronic spectrum Methods 0.000 description 2
- 238000005516 engineering process Methods 0.000 description 2
- 239000007789 gas Substances 0.000 description 2
- 239000003446 ligand Substances 0.000 description 2
- 229910052751 metal Inorganic materials 0.000 description 2
- 239000002184 metal Substances 0.000 description 2
- 239000007787 solid Substances 0.000 description 2
- 238000006467 substitution reaction Methods 0.000 description 2
- 229910001152 Bi alloy Inorganic materials 0.000 description 1
- 229910014454 Ca-Cu Inorganic materials 0.000 description 1
- MYMOFIZGZYHOMD-UHFFFAOYSA-N Dioxygen Chemical compound O=O MYMOFIZGZYHOMD-UHFFFAOYSA-N 0.000 description 1
- 238000004833 X-ray photoelectron spectroscopy Methods 0.000 description 1
- 238000000026 X-ray photoelectron spectrum Methods 0.000 description 1
- CFJRGWXELQQLSA-UHFFFAOYSA-N azanylidyneniobium Chemical compound [Nb]#N CFJRGWXELQQLSA-UHFFFAOYSA-N 0.000 description 1
- 239000003795 chemical substances by application Substances 0.000 description 1
- 238000000151 deposition Methods 0.000 description 1
- 230000008021 deposition Effects 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 229910001882 dioxygen Inorganic materials 0.000 description 1
- 238000009826 distribution Methods 0.000 description 1
- 230000005684 electric field Effects 0.000 description 1
- 230000001747 exhibiting effect Effects 0.000 description 1
- RTRWPDUMRZBWHZ-UHFFFAOYSA-N germanium niobium Chemical compound [Ge].[Nb] RTRWPDUMRZBWHZ-UHFFFAOYSA-N 0.000 description 1
- 239000012535 impurity Substances 0.000 description 1
- 238000010348 incorporation Methods 0.000 description 1
- 239000011229 interlayer Substances 0.000 description 1
- 238000001659 ion-beam spectroscopy Methods 0.000 description 1
- 239000010985 leather Substances 0.000 description 1
- 239000002245 particle Substances 0.000 description 1
- 239000000843 powder Substances 0.000 description 1
- 238000000926 separation method Methods 0.000 description 1
- 238000005245 sintering Methods 0.000 description 1
- 238000005477 sputtering target Methods 0.000 description 1
- 238000001947 vapour-phase growth Methods 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
- Inorganic Compounds Of Heavy Metals (AREA)
- Superconductor Devices And Manufacturing Methods Thereof (AREA)
- Superconductors And Manufacturing Methods Therefor (AREA)
- Physical Vapour Deposition (AREA)
Abstract
Description
【発明の詳細な説明】
産業上の利用分野
本発明は、１００Ｋ以上の高臨界温度が期待される少な
くともビスマスを含む薄膜超電導体の製造方法に関する
。DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a method for producing a thin film superconductor containing at least bismuth, which is expected to have a high critical temperature of 100 K or higher.
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
ニオブ（ＮｂＮ）やゲルマニウムニオブ（Ｎｂ３Ｇｅ）
などが知られていたが、これらの材料の臨界温度は高々
２４にであった。一方、ペロブスカイト系３元化合物は
、さらに高い臨界温度が期待されＮ Ｂａ−Ｌａ−Ｃ
ｕ−０系の高温超電導体が提案された ［シ゛エイ・シ
゛−・テ°ント°ルフ アント° ケー・ニー・ミュラ
ー、（ファイト シュリフト フェアフィシ゛−り ヘ
゛−） −コンテ゛ン訃 マター （Ｊ、Ｇ、Ｄｅｎ
ｄｏｒｚ ａｎｄ Ｋ、Ａ、Ｍｕｌｌｅｒ、（Ｚｅ
ｔｓｈｒｌｆｔ Ｆｕｒｐｈｙｓｉ Ｂ）−Ｃｏｎｄ
ｅｎｓｅｄ Ｍａｔｔｅｒ １１ｉ４．＋８９−１９３
（１９８Ｇ）） コ。Conventional technology Niobium nitride (NbN) and germanium niobium (Nb3Ge) are used as A15 type binary compounds as high-temperature superconductors.
were known, but the critical temperature of these materials was at most 24°C. On the other hand, perovskite ternary compounds are expected to have even higher critical temperatures, and N Ba-La-C
U-0 series high-temperature superconductors were proposed.
dorz and K, A, Muller, (Ze
tshrlft Furphysi B)-Cond
ensed Matter 11i4. +89-193
(198G)) Ko.
さらに、Ｂ Ｉ−Ｓ ｒ −Ｃａ −Ｃｕ−０系の材料
が１００に以上の臨界温度を示すことも発見された［エ
イチ・マエク゛、ワイ・タナ力、エム・フクトミ アン
ド ティー・ア号へシ゛ヤハニース゛・ジャーナル・オ
フ゛ ・アプライドｎａｋａ，Ｍ．Ｆｕｋｕｔｏｍｌ
ａｎｄ Ｔ．Ａｓａｎｏ．Ｊａｐａｎｅｓｅ Ｊ
ｏｕｒｎａｌｏｆ ＡｐｐＨｅｄ Ｐｈｙｓｉｃｓ
Ｖｏｌ．２７，Ｌ２０９−２１０（１９８８）］
。Furthermore, it was discovered that materials of the BI-Sr-Ca-Cu-0 system exhibit a critical temperature of over 100°C.・Journal Off゛ ・Applied naka, M. Fukutoml
and T. Asano. Japanese J
our own applied physics
Vol. 27, L209-210 (1988)]
.
この種の材料の超電導機構の詳細は明らかではないが、
臨界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
期待される。Although the details of the superconducting mechanism of this type of material are not clear,
The critical temperature may be higher than room temperature, and as a high-temperature superconductor, it is expected to have more promising properties than conventional binary compounds.
発明が解決しようとする課題
しかしながら、Ｂｌ−Ｓｒ−Ｃａ−Ｃｕ−０系の材料は
、現在の技術では主として焼結という過程でしか形成で
きないため、セラミックの粉末あるいはブロックの形状
でしか得られない。一方、この種の材料を実用化する場
合、薄膜状に加工することが強く要望されているが、従
来の技術では、良好な超電導特性を有する薄膜作製は難
しいものであった。すなわち、Ｂｌ−Ｓｒ−Ｃａ−Ｃｕ
−０系には臨界温度の異なるいくつかの相が存在するこ
とが知られているが、特に１００に以上の臨界温度を持
つ相を薄膜の形態で達成するのは非常に困難とされてい
た。Problems to be Solved by the Invention However, with current technology, Bl-Sr-Ca-Cu-0 based materials can only be formed through the process of sintering, so they can only be obtained in the form of ceramic powder or blocks. . On the other hand, when this type of material is to be put to practical use, there is a strong demand for processing it into a thin film, but it has been difficult to fabricate a thin film with good superconducting properties using conventional techniques. That is, Bl-Sr-Ca-Cu
It is known that there are several phases with different critical temperatures in the −0 system, but it has been extremely difficult to achieve a phase with a critical temperature of 100 or higher in the form of a thin film. .
また、従来このＢｌ系において良好な超電導特性を示す
薄膜を形成するためには少なくとも７００°Ｃ以上の熱
処理あるいは形成時の加熱が必要であり集積化デバイス
を構成することはたいへん困難であるとされていた。Furthermore, in order to form a thin film exhibiting good superconducting properties in this Bl system, it has been thought that heat treatment at least 700°C or higher or heating during formation is required, making it extremely difficult to construct an integrated device. was.
本発明は、このような従来技術の課題を解決することを
目的とする。The present invention aims to solve the problems of the prior art.
課題を解決するための手段
本発明の超電導体の製造方法は、基体上に少なくともビ
スマスを含む酸化物と、少なくともストロンチウムを含
む酸化物と、少なくともカルシウムを含む酸化物と少な
くとも銅を含む酸化物とを周期的に積層させて得るもの
であり、その積層構造の中でストロンチウムの一部をカ
ルシウムで、及び／またはカルシウムの一部をストロン
チウムで置換するものである。Means for Solving the Problems The method for manufacturing a superconductor of the present invention provides an oxide containing at least bismuth, an oxide containing at least strontium, an oxide containing at least calcium, and an oxide containing at least copper on a substrate. It is obtained by periodically stacking strontium and/or calcium in the stacked structure.
作用
本発明は、異なる物質を周期的に積層させて新しい薄膜
を作る方法は金属薄膜、酸化物薄膜でいくつか試みられ
ているが、基体温度を高くすると層間拡散のため周期構
造が消失してしまうことが常識であった。このため通常
は周期構造を作る場合は基体の冷却を行なうこともある
。本発明者らはこのＢｌを含む酸化物超電導体に対し、
例えば、異なる２つ以上のターゲットをもちいたスパッ
タリングによりストロンチウムの一部をカルシウムで、
そして／またはカルシウムの一部をストロンチウムで置
換し、超電導薄膜の臨界温度と薄膜の周期的結晶構造中
での原子配列が関係することを１した。ストロンチウム
をカルシウムで、そしてカルシウムをストロンチウムで
置換した場合、置換量を零からだんだんと増やして行く
ことにより臨界温度の上昇がみられた。ストロンチウム
の４０％をカルシウムで、そしてカルシウムの４０％を
ストロンチウムで置換した場合臨界温度が高くまた超電
導特性の再現性もすぐれていた。５０％以上置換すると
薄膜の結晶性が減少し、また臨界温度も低下する。本発
明により良質で高性能な薄膜超電導体を再現性良（得る
ことが可能となった。Effects of the present invention The method of creating a new thin film by periodically layering different materials has been tried in several ways for metal thin films and oxide thin films, but when the substrate temperature is raised, the periodic structure disappears due to interlayer diffusion. It was common sense to put it away. For this reason, when creating a periodic structure, the substrate is usually cooled. For this oxide superconductor containing Bl, the present inventors
For example, by sputtering using two or more different targets, some of the strontium can be converted into calcium.
And/or some of the calcium was replaced with strontium, and the critical temperature of the superconducting thin film was found to be related to the atomic arrangement in the periodic crystal structure of the thin film. When strontium was replaced with calcium and calcium was replaced with strontium, an increase in the critical temperature was observed by gradually increasing the replacement amount from zero. When 40% of strontium was replaced with calcium and 40% of calcium was replaced with strontium, the critical temperature was high and the reproducibility of superconducting properties was also excellent. If the substitution exceeds 50%, the crystallinity of the thin film decreases and the critical temperature also decreases. The present invention has made it possible to obtain high-quality, high-performance thin film superconductors with good reproducibility.
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
明する。Examples Examples of the present invention will be described below with reference to the drawings.
まず、本発明者らの検討例を述べる。すなわち、例えば
ビスマスのターゲットと適当に組成比を変化させたスト
ロンチウムとカルシウムの第１の合金ターゲットと銅の
ターゲットそして適当に組成比を変化させたカルシウム
とストロンチウムの第２の合金ターゲットをアルゴンと
酸素混合ガス中で交互にスパッタリングし、ＭｇＯ（１
００）基体上に周期的に積層させた。ストロンチウムの
４０％をカルシウムで、そしてカルシウムの４０％をス
トロンチウムで置換した場合６５０℃以下の基体温度で
も１００に以上の臨界温度を持つ相を安定に作製し得る
ことを発見した。第１図は得られた薄膜のＸ線回折バタ
ンであり、これまでセラミック超電導体において得られ
ている１００に以上の臨界温度をもつ相の結晶系、格子
常数と一致する。第２図（ａ）、 （ｂ）は得られた
薄膜のＸ線光電子スペクトルである。Ｘ線により励起さ
れ固体中から飛び出した光電子の束縛エネルギはその電
子が固体中で存在していた原子の電子状態を反映してい
る。例えばストロンチウムの同じ内殻準位の電子でもそ
の電子が存在していたストロンチウム原子の結晶中での
位置が異なるとそれぞれの電子が置かれていた電場の大
きさの違いが束縛エネルギに反映される。つまり結晶中
での配位子の距離や数そしてその種類の違いをこの電子
スペクトルから知ることが出来る。配位子との距離が大
きく、その数が多い方が束縛エネルギが小さくなる。こ
こではストロンチウムとカルシウムの３ｄ１２ｐ電子の
スペクトルを示している。電子の全軌道角運動量が保存
されるのでスペクトルの分離は３ｄ５／２，２ｐ３／２
の電子スペクトルについてのみおこなった。ストロンチ
ウムとカルシウムが結晶中で局在しているならば、それ
ぞれの内殻電子スペクトルは単一成分からなる。この図
からはそれぞれのスペクトルが２成分よりなることが分
かる。つまり結晶中でストロンチウムとカルシウムの４
０％が互いに原子位置を置換していることになる（これ
はストロンチウムの層：第４図の層Ａとカルシウムの層
：第４図の層Ｂの各々の層においてストロンチウムとカ
ルシウムの２０％が互いに置換していることになる）。First, an example of the study conducted by the present inventors will be described. That is, for example, a bismuth target, a first alloy target of strontium and calcium with an appropriately changed composition ratio, a copper target, and a second alloy target of calcium and strontium with an appropriately changed composition ratio are mixed with argon and oxygen. MgO (1
00) were periodically layered on the substrate. It has been discovered that when 40% of strontium is replaced with calcium and 40% of calcium is replaced with strontium, a phase having a critical temperature of 100 or higher can be stably produced even at a substrate temperature of 650° C. or lower. Figure 1 shows the X-ray diffraction pattern of the obtained thin film, which matches the crystal system and lattice constant of a phase with a critical temperature of 100 or more that has been obtained in ceramic superconductors. FIGS. 2(a) and 2(b) are X-ray photoelectron spectra of the obtained thin film. The binding energy of a photoelectron excited by X-rays and ejected from a solid reflects the electronic state of the atom in which the electron existed in the solid. For example, even if electrons are in the same core level of strontium, if the position of the strontium atom in which the electron exists differs in the crystal, the difference in the magnitude of the electric field in which each electron was placed will be reflected in the binding energy. . In other words, the distance, number, and type of ligands in the crystal can be determined from this electronic spectrum. The greater the distance to the ligand and the greater the number, the smaller the binding energy. Here, the spectra of 3d12p electrons of strontium and calcium are shown. Since the total orbital angular momentum of the electron is conserved, the spectrum separation is 3d5/2, 2p3/2
This was done only for the electronic spectra of . If strontium and calcium are localized in the crystal, each core electron spectrum consists of a single component. It can be seen from this figure that each spectrum consists of two components. In other words, 4 of strontium and calcium in the crystal.
(This means that 20% of strontium and calcium have replaced each other's atomic positions in the strontium layer: layer A in Figure 4 and the calcium layer: layer B in Figure 4. (They are replacing each other.)
従来の単一元素ターゲットを用いた場合には基体温度を
７００℃以上としなければ１００Ｋ以上の相を実現する
ことはできなかった。この方法では、高温を利用し拡散
を用いるため温度変化に敏感であり特性の再現性に問題
があった。発明者らは例えばストロンチウムの４０％を
カルシウムで、そしてカルシウムの４０％をストロンチ
ウムで置換した場合、基体温度４００−６５０ ”Ｃで
ビスマスとストロンチウムの合金ターゲットそしてスト
ロンチウムとカルシウムの合金ターゲットのスパッタレ
ートを適宜に調整すると、積層周期に対応して１００Ｋ
以上の相が出現し、薄膜で１１０にの臨界温度も得られ
、臨界温度の上昇も図られることを見いだした。また積
層を周期的ではなく同時に行なった場合には８０にの臨
界温度を持つ相しか作製できなかった。作製した薄膜は
そのままの状態でも臨界温度を示すが、酸素中５００−
７００℃程度で熱処理を行なうとより確実に１００に以
上の臨界温度を示した。When using a conventional single-element target, it was not possible to realize a phase of 100 K or higher unless the substrate temperature was 700° C. or higher. This method uses high temperature and diffusion, so it is sensitive to temperature changes and has problems in reproducibility of characteristics. For example, the inventors found that when 40% of the strontium was replaced with calcium and 40% of the calcium was replaced with strontium, the sputtering rate of a bismuth and strontium alloy target and a strontium and calcium alloy target at a substrate temperature of 400-650''C was If adjusted appropriately, it will be 100K depending on the lamination period.
It has been found that the above phases appear, a critical temperature of 110°C can be obtained in a thin film, and that the critical temperature can also be raised. Moreover, when the lamination was carried out simultaneously rather than periodically, only a phase having a critical temperature of 80°C could be produced. The prepared thin film exhibits a critical temperature even in its original state, but at 500°C in oxygen.
When the heat treatment was performed at about 700°C, the critical temperature of 100°C or more was more reliably shown.
ビスマスおよびストロンチウム、カルシウム、銅を含む
酸化物とを周期的に積層させる方法としては、いくつか
考えられる。一般に、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
相成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、周期的積層を達成することができる。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た。この理由は、成膜中のガス
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る。しかしながら
、本発明者らは、このＢｌ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
ろ、以外にも良好な積層膜作製が可能なことを発見した
。スパッタ中の高い酸素ガス圧およびスパッタ放電が、
Ｂｔ系の１００Ｋ以上の臨界温度を持つ相の形成に都合
がよいためではなかろうかと考えられる。特にストロン
チウムの層（：第４図層Ａ）のストロンチウムの２０％
をカルシウムで、そしてカルシウムのｆｆｉ （： 第
４図層Ｂ）のカルシウムの２０％をストロンチウムで置
換した場合、特に低い温度で安定な膜が再現性よく得ら
れることが分かった。There are several possible methods for periodically stacking bismuth and oxides containing strontium, calcium, and copper. In general, periodic stacking can be achieved by controlling an opening/closing shutter in front of the evaporation source in an MBE device or multi-source EB evaporation device, or by switching the type of gas during production using the vapor phase growth method. can. However, sputtering deposition has traditionally been considered unsuitable for this type of extremely thin layer stacking. The reason for this is thought to be the incorporation of impurities due to the high gas pressure during film formation and damage caused by high energy particles. However, the present inventors discovered that it is possible to produce a good laminated film in other ways by laminating different thin layers on this Bl-based oxide superconductor by sputtering. The high oxygen gas pressure and sputter discharge during sputtering
It is thought that this is because it is convenient for the formation of a Bt-based phase having a critical temperature of 100K or more. In particular, 20% of the strontium in the strontium layer (layer A in Figure 4)
It has been found that when strontium replaces 20% of the calcium in the ffi of calcium (layer B in Figure 4), a stable film can be obtained with good reproducibility, especially at low temperatures.
スパッタ蒸着で異なる物質を積層させる他の方法として
は、組成分布を設けた１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が、組
成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成することができる。こ
の場合、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
することができる。また基板を周期的に運動させて各々
ターゲットの上を移動させる方法でも作製が可能である
。レーザースパッタあるいはイオンビームスパッタを用
いた場合には、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
積層膜が実現される。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Ｂｉ系酸化物
の周期的積層が作製可能となる。Another method of stacking different materials by sputter deposition is to periodically control the discharge position of one sputtering target with a composition distribution, but there is also a method of sputtering multiple targets with different compositions. This can be achieved relatively easily using . In this case, a periodic laminated film can be produced by periodically controlling the amount of sputtering for each of a plurality of targets, or by providing a shutter in front of the target and opening and closing it periodically. It can also be manufactured by a method in which the substrate is moved periodically and moved over each target. When laser sputtering or ion beam sputtering is used, periodic laminated films can be realized by periodically moving a plurality of targets and periodically changing the targets irradiated with the beam. In this way, by sputtering using a plurality of targets, a periodic stack of Bi-based oxides can be produced relatively easily.
以下本発明の内容をさらに深く理解するために、具体的
な実施例を示す。In order to further understand the content of the present invention, specific examples will be shown below.
（実施例１）
Ｂｌおよび５ｒＣａ合金、Ｃｕ、ＣａＳｒ合金の計４個
のターゲットを用い、第３図に示すように配置した。す
なわち、Ｍｇ０（１００）基体３１に焦点を結ぶように
各ターゲットが約３０度傾いて設置されている。ターゲ
ットの前方には回転するシャッター３２があり、その中
に設けれたスリット３３の回転によりＢＩ＋５ｒＣａ合
金→Ｃｕ→ＣａＳｒ合金→Ｃｕ４ＣａＳｒ合金→Ｃｕ−
＞５ｒＣａ合金→Ｂ１というサイクルでスパッタ蒸着が
行われる。(Example 1) A total of four targets of Bl and 5rCa alloy, Cu, and CaSr alloy were used and arranged as shown in FIG. That is, each target is installed at an angle of about 30 degrees so as to focus on the Mg0 (100) substrate 31. There is a rotating shutter 32 in front of the target, and by rotating a slit 33 provided in it, BI+5rCa alloy→Cu→CaSr alloy→Cu4CaSr alloy→Cu−
Sputter deposition is performed in a cycle of >5rCa alloy→B1.
基体３１をヒーター３４で約６００″Ｃに加熱し、アル
ゴン：酸素（５： １）混合雰囲気３Ｐａのカス中で
各ターゲットのスパッタリングをおこなった。各ターゲ
ットのスパッタ電流を、ＢＩ：３０ｍ ＡＩ Ｓ ｒ
Ｃａ合金： ５０ｍＡ、 Ｃｕ： ２５０ｍＡ
。The substrate 31 was heated to about 600''C with a heater 34, and sputtering of each target was performed in a mixed atmosphere of argon:oxygen (5:1) at 3 Pa.The sputtering current of each target was set to BI: 30 m AI S r
Ca alloy: 50mA, Cu: 250mA
.
ＣａＳｒ合金５合金５己
周期を１０分間として周期的積層を行ったところ、基体
温度６００℃で１００Ｋ以上の臨界温度を持つ層を作製
することができた。約１０時間の蒸着により１ ０ ０
ｎｍ程度の薄膜が作製された。組成はＢｉ： Ｓｒ：
Ｃａ： Ｃｕ＝２： ２： ２： ３であった。When periodic lamination was carried out with a period of 10 minutes, a layer having a critical temperature of 100 K or higher at a substrate temperature of 600° C. could be produced. 100 after about 10 hours of vapor deposition.
A thin film on the order of nm was fabricated. The composition is Bi: Sr:
Ca: Cu=2:2:2:3.
このままの状態でもこの薄膜は１００Ｋ以上の臨界温度
を示したが、さらに酸素中で８５０℃、１時間の熱処理
を行うと再現性が非常に良くなった。Even in this state, this thin film showed a critical temperature of 100 K or more, but when it was further heat-treated in oxygen at 850° C. for 1 hour, the reproducibility became very good.
１００に以上の臨界温度を持つ相の構造を今回の検討結
果も含めて整理すると第４図に示す様になる。基本的に
は、金属元素がＢ１→Ｓｒ−＊Ｃｕ＋Ｃａ→Ｃｕー４ー
Ｃａ→Ｃｕ→Ｓｒ→Ｂ１の順序で並んだ酸化物の届から
成り立っており、Ｃｕ酸化物の層にホールを供給するの
に都合が良いように、第１表に示すようにＣａより＋１
価だけ価数の大きいＳｒが一部のＣａを置換している。The structure of phases with a critical temperature of 100 or higher, including the results of this study, is summarized as shown in Figure 4. Basically, the metal element is made up of oxides arranged in the order of B1 → Sr-*Cu+Ca → Cu-4-Ca → Cu → Sr → B1, which supplies holes to the Cu oxide layer. For convenience, as shown in Table 1, +1 from Ca.
Sr, which has a higher valence, replaces a part of Ca.
第１表 Ｓｒの酸化物層は一部Ｃａにより置換されている。Table 1 The Sr oxide layer is partially replaced by Ca.
これは結晶全体としての電気的中性を保ち、また構造の
周期性を保つために役立っているものとかんかえられる
。本発明の製造方法は、この構造を作るのに非常に有効
と考えられる。また従来に比べて低温で形成されるよう
になった。これは従来と異なり蒸着中または蒸着後の各
元素間の拡散を用いるのではなく、蒸着時点からの元素
置換の効果である。また、ここではターゲットの例とじ
て合金を用いる場合を示したが混合酸化物でも高周波ス
パッタ法を用いれば可能である。This can be thought of as helping to maintain the electrical neutrality of the crystal as a whole and the periodicity of the structure. The manufacturing method of the present invention is considered to be very effective in manufacturing this structure. Also, it is now formed at a lower temperature than before. This differs from the conventional method in that it does not use diffusion between elements during or after vapor deposition, but is an effect of element substitution from the time of vapor deposition. Moreover, although the case where an alloy is used as an example of the target is shown here, it is also possible to use a mixed oxide by using the high frequency sputtering method.
発明の効果
以上のように本発明の薄膜超電導体の製造方法は、１０
０に以上の超電導臨界温度をもつＢｉ系酸化物超電導薄
膜の再現性の良い低温プロセスを提供するものであり、
デバイスなどの応用には必須である低温でのプロセスを
確立出来る。Effects of the Invention As described above, the method for producing a thin film superconductor of the present invention has a
The present invention provides a low-temperature process with good reproducibility for Bi-based oxide superconducting thin films having a superconducting critical temperature of 0.0 or higher,
It is possible to establish low-temperature processes that are essential for device applications.
第１図は本発明の実施例に於ける薄膜超電導体のＸ線回
折バタンを示すグラフ、第２図は本発明の実施に於ける
薄膜超電導体のＸ線光電子分光スペクトルを示すグラフ
、第３図は本発明の実施例に於ける薄膜超電導体の製造
方法に使用される装置を示す斜視図、 第４図は本発明
の実施例に於ける薄膜超電導体の結晶中の原子配列を示
す構成図である。
３１−−Ｍｇ０基体、３２−一シャッター ３３−一ス
リット、３４−ヒーター
代理人の氏名 弁理士 栗野重孝 はか１名第
図
乙
ｄり
Ｃ２ン
第
図
Ｚ＝Ｚ−３７ｒｇｏ基沫
第
図
（勾
１３６ ｔ３ｂ
＊ −字’ｘじトルノ←（エレクトロレザ１ルト）ｔｂ
）
３！ｂ Ｍ４
１４工序ルキにレクトロンｍｌルト）
第
図
○○○○ｅ−５・
○○Ｏ○FIG. 1 is a graph showing the X-ray diffraction spectrum of the thin film superconductor in the embodiment of the present invention, FIG. 2 is a graph showing the X-ray photoelectron spectroscopy spectrum of the thin film superconductor in the implementation of the present invention, and FIG. The figure is a perspective view showing an apparatus used in a method for manufacturing a thin film superconductor in an embodiment of the present invention. Figure 4 is a configuration showing the atomic arrangement in a crystal of a thin film superconductor in an embodiment of the present invention. It is a diagram. 31--Mg0 base, 32-1 shutter 33-1 slit, 34-Heater agent's name Patent attorney Shigetaka Kurino 136 t3b * -character'xjitorno←(electro leather 1st) tb
) 3! b M4 14th step Ruki and Lectron ml route) Figure ○○○○e-5・○○O○
Claims (5)
ストロンチウムとカルシウムを含む酸化物と、銅を含む
酸化物とを周期的に積層させて得ることを特徴とする薄
膜超電導体の製造方法。(1) An oxide containing at least bismuth on the substrate,
A method for producing a thin film superconductor, characterized in that it is obtained by periodically stacking an oxide containing strontium and calcium and an oxide containing copper.
ストロンチウム酸化物の一部をカルシウム酸化物で置換
して形成したことを特徴とする請求項１記載の薄膜超電
導体の製造方法。(2) The method for manufacturing a thin film superconductor according to claim 1, wherein the oxide containing strontium and calcium is formed by replacing a portion of the strontium oxide with calcium oxide.
カルシウム酸化物の一部をストロンチウム酸化物で置換
して形成したことを特徴とする請求項１記載の薄膜超電
導体の製造方法。(3) The method for manufacturing a thin film superconductor according to claim 1, wherein the oxide containing strontium and calcium is formed by replacing a portion of calcium oxide with strontium oxide.
を特徴とする請求項１〜３のいずれかに記載の薄膜超電
導体の製造方法。(4) The method for producing a thin film superconductor according to any one of claims 1 to 3, characterized in that the evaporation of the laminated material is performed by a sputtering method.
複数個のターゲットのスパッタリング法で行なうことを
特徴とする請求項１〜３のいずれかに記載の薄膜超電導
体の製造方法。(5) The method for producing a thin film superconductor according to any one of claims 1 to 3, characterized in that the evaporation of the laminated material is performed by sputtering using a plurality of targets having at least two types of compositions.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP1118971A JP2502743B2 (en) | 1989-05-12 | 1989-05-12 | Method of manufacturing thin film superconductor |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP1118971A JP2502743B2 (en) | 1989-05-12 | 1989-05-12 | Method of manufacturing thin film superconductor |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH02296730A true JPH02296730A (en) | 1990-12-07 |
| JP2502743B2 JP2502743B2 (en) | 1996-05-29 |
Family
ID=14749815
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP1118971A Expired - Lifetime JP2502743B2 (en) | 1989-05-12 | 1989-05-12 | Method of manufacturing thin film superconductor |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP2502743B2 (en) |
Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS63169375A (en) * | 1986-12-29 | 1988-07-13 | Toyobo Co Ltd | Sputtering method |
| JPH01157406A (en) * | 1987-08-24 | 1989-06-20 | Sumitomo Electric Ind Ltd | Production of compound oxide superconducting thin film |
| JPH0259403A (en) * | 1988-08-26 | 1990-02-28 | Hitachi Ltd | Manufacture of oxide superconducting material, ion-beam sputtering device, and electronic element |
| JPH02120229A (en) * | 1988-10-27 | 1990-05-08 | Nec Corp | Production of superconducting thin film of oxide |
| JPH02120232A (en) * | 1988-10-27 | 1990-05-08 | Nec Corp | Production of superconducting thin film of oxide |
-
1989
- 1989-05-12 JP JP1118971A patent/JP2502743B2/en not_active Expired - Lifetime
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS63169375A (en) * | 1986-12-29 | 1988-07-13 | Toyobo Co Ltd | Sputtering method |
| JPH01157406A (en) * | 1987-08-24 | 1989-06-20 | Sumitomo Electric Ind Ltd | Production of compound oxide superconducting thin film |
| JPH0259403A (en) * | 1988-08-26 | 1990-02-28 | Hitachi Ltd | Manufacture of oxide superconducting material, ion-beam sputtering device, and electronic element |
| JPH02120229A (en) * | 1988-10-27 | 1990-05-08 | Nec Corp | Production of superconducting thin film of oxide |
| JPH02120232A (en) * | 1988-10-27 | 1990-05-08 | Nec Corp | Production of superconducting thin film of oxide |
Also Published As
| Publication number | Publication date |
|---|---|
| JP2502743B2 (en) | 1996-05-29 |
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