JPH07106904B2 - Method of manufacturing thin film superconductor - Google Patents
Method of manufacturing thin film superconductorInfo
- Publication number
- JPH07106904B2 JPH07106904B2 JP1339012A JP33901289A JPH07106904B2 JP H07106904 B2 JPH07106904 B2 JP H07106904B2 JP 1339012 A JP1339012 A JP 1339012A JP 33901289 A JP33901289 A JP 33901289A JP H07106904 B2 JPH07106904 B2 JP H07106904B2
- Authority
- JP
- Japan
- Prior art keywords
- thin film
- oxygen
- substrate
- cuo
- film superconductor
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
Links
- 239000010409 thin film Substances 0.000 title claims description 39
- 239000002887 superconductor Substances 0.000 title claims description 18
- 238000004519 manufacturing process Methods 0.000 title claims description 10
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims description 28
- 239000013078 crystal Substances 0.000 claims description 28
- 239000001301 oxygen Substances 0.000 claims description 28
- 229910052760 oxygen Inorganic materials 0.000 claims description 28
- 239000000758 substrate Substances 0.000 claims description 22
- 239000007789 gas Substances 0.000 claims description 12
- 239000010408 film Substances 0.000 claims description 11
- 238000010438 heat treatment Methods 0.000 claims description 11
- 238000000034 method Methods 0.000 claims description 11
- 230000009467 reduction Effects 0.000 claims description 11
- 238000004544 sputter deposition Methods 0.000 claims description 11
- 229910052731 fluorine Inorganic materials 0.000 claims description 7
- 239000011737 fluorine Substances 0.000 claims description 7
- YCKRFDGAMUMZLT-UHFFFAOYSA-N Fluorine atom Chemical compound [F] YCKRFDGAMUMZLT-UHFFFAOYSA-N 0.000 claims description 6
- 229910052779 Neodymium Inorganic materials 0.000 claims description 6
- 239000011261 inert gas Substances 0.000 claims description 6
- 229910052684 Cerium Inorganic materials 0.000 claims description 5
- 229910052772 Samarium Inorganic materials 0.000 claims description 4
- 229910052776 Thorium Inorganic materials 0.000 claims description 4
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 description 12
- 229910052786 argon Inorganic materials 0.000 description 6
- 229910002367 SrTiO Inorganic materials 0.000 description 5
- 230000000694 effects Effects 0.000 description 4
- 239000000463 material Substances 0.000 description 4
- 229910002480 Cu-O Inorganic materials 0.000 description 3
- 229910052777 Praseodymium Inorganic materials 0.000 description 3
- 238000005516 engineering process Methods 0.000 description 3
- 230000001590 oxidative effect Effects 0.000 description 3
- 230000008569 process Effects 0.000 description 3
- 230000007704 transition Effects 0.000 description 3
- 206010021143 Hypoxia Diseases 0.000 description 2
- 229910052796 boron Inorganic materials 0.000 description 2
- 239000000919 ceramic Substances 0.000 description 2
- 229910052802 copper Inorganic materials 0.000 description 2
- 238000009792 diffusion process Methods 0.000 description 2
- 239000000203 mixture Substances 0.000 description 2
- 229910052574 oxide ceramic Inorganic materials 0.000 description 2
- 239000011224 oxide ceramic Substances 0.000 description 2
- 238000010791 quenching Methods 0.000 description 2
- 230000000171 quenching effect Effects 0.000 description 2
- 238000005245 sintering Methods 0.000 description 2
- VEALVRVVWBQVSL-UHFFFAOYSA-N strontium titanate Chemical compound [Sr+2].[O-][Ti]([O-])=O VEALVRVVWBQVSL-UHFFFAOYSA-N 0.000 description 2
- 238000006467 substitution reaction Methods 0.000 description 2
- 238000007740 vapor deposition Methods 0.000 description 2
- 229910017493 Nd 2 O 3 Inorganic materials 0.000 description 1
- 238000002441 X-ray diffraction Methods 0.000 description 1
- 230000009471 action Effects 0.000 description 1
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 229910010293 ceramic material Inorganic materials 0.000 description 1
- 239000004020 conductor Substances 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 239000002178 crystalline material Substances 0.000 description 1
- 238000002425 crystallisation Methods 0.000 description 1
- 230000008025 crystallization Effects 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 230000007812 deficiency Effects 0.000 description 1
- 230000002950 deficient Effects 0.000 description 1
- 125000001153 fluoro group Chemical group F* 0.000 description 1
- 238000001755 magnetron sputter deposition Methods 0.000 description 1
- 230000007246 mechanism Effects 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000000843 powder Substances 0.000 description 1
- 230000001737 promoting effect Effects 0.000 description 1
- 238000005477 sputtering target 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
- Inorganic Compounds Of Heavy Metals (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、高臨界温度を持つ酸化物超電導体の薄膜超電
導導体製造方法、特にNd2CuO4型結晶構造の酸化物超電
導体薄膜の製造方法に関するものである。TECHNICAL FIELD The present invention relates to a method for producing a thin film superconducting conductor of an oxide superconductor having a high critical temperature, and more particularly to a method of producing an oxide superconducting thin film of Nd 2 CuO 4 type crystal structure. It is a thing.
従来の技術 高い超電導転移温度を持つ酸化物超電導体として、Ba−
La−Cu−Ｏ系の超電導体が発見された［ジェイ、ジー、
ベドノルツ アンド ケイ、エー、ミュラー（J.G.Bndn
orz and K.A.Muller），ツァイトシュリフト フュア
フィジーク（Zeitshriftfur Physik B）−Condensed Ma
tter,vol.64,189−193（1986）］。これ以来数々の新し
い酸化物超電導体が発見されるに至った。Conventional technology As an oxide superconductor with a high superconducting transition temperature, Ba-
La-Cu-O superconductor was discovered [J, G,
Bednorz and Kay, A, Muller (JGBndn
orz and KAMuller), Zeit Schriftfuhr
Zeitshriftfur Physik B-Condensed Ma
tter, vol.64, 189-193 (1986)]. Since then, many new oxide superconductors have been discovered.
ところで最近、これら従来の酸化物超電導体とは常電導
状態における電荷輸送担体が異なる、Nd−Ce−Cu−Ｏに
代表されるNd2CuO4型結晶構造の新しい酸化物超電導体
が発見された［ワイ．トクラ、エイチ．タカギ アンド
エス．ウチダ（Y.Tokura,H.Takagi and S.Uchida），
ネイチャー（Nature）vol.337,345−347（1989）］。こ
の種の材料の超電導機構の詳細は明らかではないが、転
移温度がさらに高くなる可能性があり、また新しいデバ
イスの実現等の有望な応用が期待される。By the way, recently, a new oxide superconductor having an Nd 2 CuO 4 type crystal structure represented by Nd-Ce-Cu-O, which is different from these conventional oxide superconductors in the charge transport carrier in the normal conduction state, was discovered. [Yi. Tokura, H. Takagi and S. Uchida (Y.Tokura, H.Takagi and S.Uchida),
Nature, vol.337, 345-347 (1989)]. The details of the superconducting mechanism of this type of material are not clear, but the transition temperature may be higher, and promising applications such as the realization of new devices are expected.
発明が解決しようとする課題 しかしながら、Nd−Ce−Cu−Ｏ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非常に困難と
されている。DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention However, since the Nd-Ce-Cu-O-based material can be formed only in the process of sintering in the present technology,
It is only available in the form of ceramic powder or blocks. On the other hand, it is strongly demanded to process this kind of material into a thin film when it is put to practical use, but it is very difficult to produce a thin film having good superconducting properties by the conventional techniques.
本発明は、このような従来技術の課題を解決することを
目的とするものである。The present invention aims to solve such problems of the conventional technology.
課題を解決するための手段 本発明は、主成分が、Nd2CuO4型結晶構造の（A1-xBx）2
CuO4で表わされる複合酸化物の超電導薄膜を作製するた
め、基本的にスパッタ蒸着法を用いて、適当な基体上に
結晶生の高い薄膜を形成すると共に、酸素欠損の導入を
行うことにより酸素の含有量を化学量論比より少ない最
適値にするというものである。ここで、ＡはNd,Sm,Prの
うちの少なくとも一種、ＢはCe,Thのうちの少なくとも
一種の元素を示す。また、ｘは、0.06≦ｘ≦0.08の範囲
の数値である。Means for Solving the Problems In the present invention, the main component is (A 1-x B x ) 2 having a Nd 2 CuO 4 type crystal structure.
In order to prepare a superconducting thin film of a complex oxide represented by CuO 4 , basically, a sputter deposition method is used to form a thin film with high crystal growth on an appropriate substrate, and oxygen defects are introduced to introduce oxygen. The content of is to be an optimum value smaller than the stoichiometric ratio. Here, A represents at least one of Nd, Sm, and Pr, and B represents at least one of Ce and Th. Further, x is a numerical value in the range of 0.06 ≦ x ≦ 0.08.
作用 本発明は、上記のような構成によって、良質で高性能な
Nd2CuO4型結晶構造の薄膜超電導体を再現性良く得るこ
とが可能となった。Action The present invention is of high quality and high performance due to the above configuration.
It has become possible to obtain thin-film superconductors with Nd 2 CuO 4 type crystal structure with good reproducibility.
実施例 本発明者らはこのNd2CuO4型結晶構造の酸化物超電導体
に対して、スパッタ蒸着法による薄膜作製を行ない、作
製条件と薄膜の超電導性の関係について詳細に調べた。
スパッタリングターゲットとしては、Ａ元素、Ｂ元素、
Cuを含む酸化物を大気中において高温で熱処理して得た
焼結体を用いた。ただしＡはNd,Sm,Prのうちの少なくと
も一種、ＢはCe,Thのうちの少なくとも一種の元素を示
す。その結果400℃〜1000℃に加熱した単結晶基体上
に、例えばNd1.85Ce0.15CuO4の薄膜を、NdとCeとCuを含
むターゲットをスパッタして成膜させ、結晶化薄膜を得
ることが出来た。そして単結晶基板の使用は、アルミナ
のような非結晶材料を基板として用いた場合に比べてNd
1.85Ce0.15CuO4薄膜の結晶性を改善するという作用があ
ることを確認した。MgO単結晶を基板として用いた場合
には、（001），あるいは（110）の結晶軸方向に配向す
る。特にSrTiO3,BaTiO3,LaAlO3,LaGaO3等のペロブスカ
イト型の結晶構造を有する単結晶を基板として使用した
場合には、その結晶軸にそってNd1.85Ce0.15CuO4の結晶
軸が配向し、良好な結晶性を持つ薄膜が得られることを
発明者らは見いだした。Example The inventors of the present invention carried out a thin film production by the sputter deposition method on the oxide superconductor having the Nd 2 CuO 4 type crystal structure, and investigated in detail the relation between the production conditions and the superconductivity of the thin film.
As the sputtering target, A element, B element,
A sintered body obtained by heat-treating an oxide containing Cu at high temperature in the atmosphere was used. However, A represents at least one element of Nd, Sm, and Pr, and B represents at least one element of Ce and Th. As a result, on a single crystal substrate heated to 400 ℃ ~ 1000 ℃, for example, a thin film of Nd 1.85 Ce 0.15 CuO 4 is sputtered with a target containing Nd, Ce and Cu to form a crystallized thin film. done. And the use of a single crystal substrate is more effective than using a non-crystalline material such as alumina as the substrate.
It was confirmed that it has the effect of improving the crystallinity of the 1.85 Ce 0.15 CuO 4 thin film. When MgO single crystal is used as the substrate, it is oriented in the (001) or (110) crystal axis direction. In particular, when a single crystal having a perovskite type crystal structure such as SrTiO 3 , BaTiO 3 , LaAlO 3 , LaGaO 3 is used as a substrate, the crystal axis of Nd 1.85 Ce 0.15 CuO 4 is oriented along the crystal axis. The inventors have found that a thin film having good crystallinity can be obtained.
さらに、通常酸化物薄膜の作製の場合、スパッタガスと
して、アルゴンなどの不活性ガスと酸素または酸化ガス
をほぼ等量混合して用いる。ところがNd2CuO4型結晶構
造の酸化物超電導体においては、スパッタガス中の酸素
あるいは酸化ガスの分圧を極端に低くして成膜すると、
意外にも良好な超電導性が、すなわち、セラミックス材
料とほぼ等しい20Kのものが、再現性良く得られること
を得られることを本発明者らは発見した。この原因は現
在のところ明らかではないが、この種の材料のセラミッ
クスの焼結においては還元雰囲気がよいと言われてお
り、スパッタ蒸着中の酸素分圧を低くすることにより不
必要な酸素が薄膜の結晶構造中に入らない、あるいは、
薄膜の組成が、Nd1.85Ce0.15CuO4-yと適当な量ｙの酸素
欠損が導入されているため、良い結果が得られているの
ではないかと思われる。さらに、酸素あるいは酸化ガス
を全く含まない不活性ガスのみの場合にも良好な超電導
特性が得られることを見いだした。不活性ガスとしては
アルゴンが比較的利用し易く、また結果も良いことを確
認した。これらの理由は、Nd2CuO4型の結晶構造を作る
にはある程度の酸素が必要ではあるが、その酸素はター
ゲットから十分供給することが可能であると思われる。Further, in the case of producing an oxide thin film, an inert gas such as argon and oxygen or an oxidizing gas are mixed in almost equal amounts and used as a sputtering gas. However, in the oxide superconductor having the Nd 2 CuO 4 type crystal structure, when the film is formed by making the partial pressure of oxygen or the oxidizing gas in the sputtering gas extremely low.
The present inventors have discovered that surprisingly good superconductivity, that is, that of 20K, which is almost equal to that of a ceramic material, can be obtained with good reproducibility. The cause of this is not clear at present, but it is said that a reducing atmosphere is good in the sintering of ceramics of this kind of material, and unnecessary oxygen can be removed in a thin film by reducing the oxygen partial pressure during sputter deposition. Does not enter the crystal structure of, or
It is considered that the thin film composition has good results because Nd 1.85 Ce 0.15 CuO 4-y and an appropriate amount of oxygen deficiency are introduced. Furthermore, they have found that good superconducting properties can be obtained even when only inert gas containing no oxygen or oxidizing gas is used. It was confirmed that argon was relatively easy to use as the inert gas and the result was good. For these reasons, some oxygen is required to form the Nd 2 CuO 4 type crystal structure, but it is considered that the oxygen can be sufficiently supplied from the target.
スパッタ蒸着した膜、特に、基体温度を750℃〜1000℃
とした膜の結晶性は、超電導特性を得るには十分である
が、さらに大気中もしくは10-3気圧以上の酸素を含んだ
雰囲気で、900℃〜1100℃の温度範囲で一定時間加熱す
ることによって結晶性を高めることができ、さらに優れ
た超電導特性を得ることができることを確認した。あわ
せて、熱処理後、室温以下に急冷することが、酸素含有
量を少なくして後の還元処理を容易にすることを見いだ
した。Films sputter-deposited, especially substrate temperatures from 750 ° C to 1000 ° C
Although the crystallinity of the film is sufficient to obtain superconducting properties, it should be heated for a certain period of time in the temperature range of 900 ° C to 1100 ° C in the atmosphere or in an atmosphere containing oxygen at 10 -3 atmospheres or more. It was confirmed that the crystallinity can be enhanced by this and further excellent superconducting properties can be obtained. At the same time, it was found that quenching after the heat treatment to room temperature or less reduces the oxygen content and facilitates the subsequent reduction treatment.
また、本発明者らは、適当な還元処理を行い、酸素欠損
の導入により酸素の含有量を化学量論比より少ない最適
値にすることによって、最適の超電導特性を得ることが
できることを見いだした。還元処理の方法としては、真
空中もしくは酸素分圧10-3気圧以下のアルゴン等の不活
性ガス雰囲気で、加熱することが有効であることを見い
だした、その際の、酸素の脱離量あるいは欠損量は、酸
素の拡散過程に強く依存する。すなわち、加熱する際の
処理温度範囲としては、500℃〜900℃が適当であるが、
必要な処理時間は、超電導体の膜厚及び表面状態によっ
ても影響を受けるが、処理温度が高いほど短い時間で済
むことを見いだした。しかしながら、処理時間が長すぎ
ると、かえって超電導性を損なわせる結果となり、各処
理温度には最適な処理時間が存在することを見いだし
た。Further, the present inventors have found that the optimum superconducting properties can be obtained by performing an appropriate reduction treatment and introducing an oxygen deficiency so that the oxygen content becomes an optimum value smaller than the stoichiometric ratio. . As a method for the reduction treatment, it was found that heating in vacuum or in an atmosphere of an inert gas such as argon with an oxygen partial pressure of 10 −3 atm or less is effective. At that time, the amount of released oxygen or The amount of deficiency strongly depends on the diffusion process of oxygen. That is, as the processing temperature range when heating, 500 ℃ ~ 900 ℃ is suitable,
It was found that the required treatment time is influenced by the film thickness and surface condition of the superconductor, but the higher the treatment temperature, the shorter the treatment time. However, it was found that if the treatment time is too long, the superconductivity is rather deteriorated, and that there is an optimum treatment time at each treatment temperature.
もう一つの還元処理の方法として、少なくともフッ素ガ
スを含んだ雰囲気下で加熱することによって酸素をフッ
素と置換すれば、超電導特性を得ることができることを
見いだした。As another reduction treatment method, it was found that superconducting properties can be obtained by replacing oxygen with fluorine by heating in an atmosphere containing at least fluorine gas.
以下、更に具体的な実施例を示す。Hereinafter, more specific examples will be shown.
NdとCeとCuを含む酸化物セラミックス焼結体をターゲッ
トとして用い、チタン酸ストロンチウム（100）面の基
体上に、高周波プレナーマグネトロンスパッタにより薄
膜作製を行なった。このターゲットは、Nd2O3、CeO2、C
uOを大気中1050℃で８時間熱処理し得た焼結体を用い
た。スパッタガスは純アルゴンガスとしたが、良好な結
晶性の薄膜が形成可能であった。この理由は、Nd2CuO4
型の結晶構造を作るにはある程度の酸素が必要で、その
酸素はターゲットから供給されるのが一番適しているこ
とによると思われる。Using an oxide ceramics sintered body containing Nd, Ce, and Cu as a target, a thin film was formed on a strontium titanate (100) plane substrate by high-frequency planar magnetron sputtering. This target is Nd 2 O 3 , CeO 2 , C
A sintered body obtained by heat-treating uO in the atmosphere at 1050 ° C. for 8 hours was used. The sputtering gas was pure argon gas, but a thin film with good crystallinity could be formed. The reason for this is Nd 2 CuO 4
It seems that some amount of oxygen is required to form the crystal structure of the mold, and the oxygen is best supplied from the target.
蒸着中の基体の温度としては400℃〜1000℃とした場合
に、低温で薄膜の電気抵抗に超伝導が兆候が認められた
が、特に750℃〜1000℃で形成した薄膜においては、ゼ
ロ抵抗が20K程度で確認され、また結晶性も良く再現性
もすぐれていた。When the temperature of the substrate during vapor deposition was 400 ° C to 1000 ° C, there was a sign of superconductivity in the electrical resistance of the thin film at low temperatures, but zero resistance was observed especially in the thin film formed at 750 ° C to 1000 ° C. Was confirmed at around 20K, and the crystallinity was good and reproducibility was excellent.
以下本発明の内容を深く理解されるために、さらに具体
的な実施例を示す。Hereinafter, more specific examples will be shown in order to deeply understand the contents of the present invention.
Nd1.85Ce0.15Cu1.5Oxの酸化物セラミックス焼結体をタ
ーゲットとして用い、MgO,あるいは、SrTiO3の（10
0），あるいは（110）面の単結晶基体上に、薄膜形成を
行なった。スパッタ電力160W、スパッタガス圧力３×10
-3Torrの条件のもとで、約１時間スパッタ蒸着すること
により、約0.5〜0.8μｍ厚の薄膜が得られた。スパッタ
ガスは純アルゴンガスとし、この際の基体温度を変化さ
せて、結晶性および出現する超伝導特性との関係を調べ
た。上記過程の後、薄膜の組成を調べたところ、金属元
素の比率はNd:Ce:Cu＝1.85:0.15:1.0とほぼ化学量論比
になっていた。また薄膜の結晶構造は、Ｘ線回折法によ
り調べられた。Using an oxide ceramics sintered body of Nd 1.85 Ce 0.15 Cu 1.5 O x as a target, MgO or SrTiO 3 (10
Thin films were formed on (0) or (110) plane single crystal substrates. Sputtering power 160W, Sputtering gas pressure 3 × 10
A thin film having a thickness of about 0.5 to 0.8 μm was obtained by performing sputter deposition for about 1 hour under the condition of −3 Torr. The sputtering gas was pure argon gas, the substrate temperature was changed at this time, and the relationship between the crystallinity and the appearing superconducting property was investigated. After the above process, when the composition of the thin film was examined, the ratio of metal elements was Nd: Ce: Cu = 1.85: 0.15: 1.0, which was almost stoichiometric. The crystal structure of the thin film was examined by X-ray diffractometry.
この結果、基板としてSrTiO3（100）基板を用いた場
合、形成された薄膜はｃ軸が基板に垂直に配向したNd2C
uO4型の結晶構造であることが判った。SrTiO3（110）基
板を用いた場合には、（103）面の薄膜が成長し、MgO
（100）面には、（110）面、（110）面には、（100）面
が、それぞれ成長した。基体温度を750℃〜1000℃とし
た膜の結晶性は、超電導特性を得るには十分であるが、
さらに大気中もしくは10-3気圧以上の酸素を含んだ雰囲
気で、900℃〜1100℃の温度範囲で１時間〜２時間加熱
することによって結晶性を高めることができ、さらに優
れた超電導特性を得ることができるとを確認した。優れ
た超電導特性を与える薄膜を結晶構造は、ｃ軸が基板に
垂直に配向したものが適していることが分かった。その
意味で基体としては、SrTiO3（100）基板のほか、BaTiO
3,LaAlO3,LaGaO3等のペロブスカイト型の結晶構造を有
する単結晶の（100）基板が優れていることを確認し
た。As a result, when the SrTiO 3 (100) substrate was used as the substrate, the formed thin film was Nd 2 C whose c-axis was oriented perpendicular to the substrate.
It was found to have a uO 4 type crystal structure. When the SrTiO 3 (110) substrate was used, the (103) plane thin film was grown and
The (110) plane was grown on the (100) plane, and the (100) plane was grown on the (110) plane. The crystallinity of the film with the substrate temperature of 750 ° C to 1000 ° C is sufficient to obtain superconducting properties,
Furthermore, the crystallinity can be enhanced by heating in the atmosphere or in an atmosphere containing oxygen of 10 -3 atmospheres or higher at a temperature range of 900 ° C to 1100 ° C for 1 to 2 hours, and further excellent superconducting properties can be obtained. I confirmed that I could do it. It has been found that a crystal structure of a thin film that gives excellent superconducting properties is suitable when the c-axis is oriented perpendicular to the substrate. In that sense, as the substrate, in addition to SrTiO 3 (100) substrate, BaTiO 3
It was confirmed that a single crystal (100) substrate having a perovskite type crystal structure such as 3 , 3 , LaAlO 3 and LaGaO 3 was excellent.
得られた薄膜の中には、成膜後あるいは上述の結晶化を
促進されるための加熱処理後に、超電導特性を示すもの
もあったが、その超電導特性は、適当な還元処理をによ
って、さらに高めることができ、また、超電導特性を示
さなかったものについても、最適の超電導特性を得るこ
とができることを見いだした。また、熱処理後、室温以
下に急冷することが、酸素含有量を少なくして後の還元
処理を容易にすることを見いだした。還元処理の方法と
しては、真空中もしくは酸素分圧10-3気圧以下のアルゴ
ン等の不活性ガス雰囲気で、加熱することが有効である
ことを見いだした。膜厚5000Aの代表的な薄膜につい
て、処理温度および処理時間を変化させて、真空中で加
熱した際の電気抵抗の温度依存性を図に示す。曲線11は
還元処理前、曲線12、13、14は、600℃でそれぞれ２、1
6、52時間処理したもの、曲線15は、800℃で２時間処理
したものである。転移温度22K以上の優れた超電導特性
を得るのに必要な処理時間は、600℃で８〜30時間、800
℃で１〜３時間処理であった。これより、酸素の脱離量
あるいは欠損量は、酸素の拡散過程に強く依存し、加熱
する際の処理温度範囲としては、500℃〜900℃が適当で
あるが、最適な処理時間は、超電導体の膜厚及び表面状
態によっても影響を受けるが、処理温度が高いほど短い
時間で済むが、最適時間範囲は狭いことを見いだした。Some of the obtained thin films showed superconducting properties after the film formation or after the heat treatment for promoting the above-mentioned crystallization, but the superconducting properties were further reduced by an appropriate reduction treatment. It has been found that the optimum superconducting properties can be obtained even for those that do not exhibit the superconducting properties. It was also found that quenching to room temperature or less after the heat treatment reduces the oxygen content and facilitates the subsequent reduction treatment. As a method for the reduction treatment, it was found that heating in vacuum or in an atmosphere of an inert gas such as argon having an oxygen partial pressure of 10 −3 atm or less is effective. The figure shows the temperature dependence of the electrical resistance of a typical thin film having a film thickness of 5000 A when heated in vacuum by changing the processing temperature and the processing time. Curve 11 is before reduction treatment, and curves 12, 13 and 14 are 2 and 1 at 600 ℃, respectively.
The curve 15 was treated for 6 to 52 hours, and the curve 15 was treated at 800 ° C. for 2 hours. The processing time required to obtain excellent superconducting properties with a transition temperature of 22K or higher is 8 to 30 hours at 600 ° C and 800
It was a treatment at 1 ° C. for 1 to 3 hours. From this, the amount of desorbed oxygen or the amount of deficient oxygen strongly depends on the diffusion process of oxygen, and a suitable processing temperature range for heating is 500 ° C to 900 ° C. It was found that the higher the treatment temperature, the shorter the time required, although the optimum time range is narrow, although it is affected by the film thickness and surface condition of the body.
さらに、本発明者らは、蒸着膜を還元し酸素含有量を少
なくする方法として、フッ素との置換効果を利用するこ
とが有効であることを確認した。例えば、フッ素を含ん
だフロンガス等の雰囲気で放電を起こし、活性なフッ素
に薄膜を曝せば、フッ素との置換効果によって酸素量を
減らすことができ良好な超電導薄膜を形成することが出
来ることを確認した。Furthermore, the present inventors have confirmed that it is effective to utilize the substitution effect with fluorine as a method of reducing the vapor deposition film to reduce the oxygen content. For example, it was confirmed that if a thin film is exposed to active fluorine by causing an electric discharge in an atmosphere such as CFCs containing fluorine, the amount of oxygen can be reduced by the effect of substitution with fluorine and a good superconducting thin film can be formed. did.
なおこの結果は、Ndの代わりにSm、Prあるいはこの少な
くとも一種を含む組合せ、またCeの代わりにThあるいは
この少なくとも一種を含む組合せでも、同様であること
が確認された。It was confirmed that this result was the same for Sm, Pr or a combination containing at least one of them instead of Nd, and Th or a combination containing at least one of these instead of Ce.
発明の効果 本発明により、良質で高性能なNd2CuO4型結晶構造の薄
膜超電導体を再現性良く得ることが可能となった。本発
明の製造方法は、この種の物質を用いたデバイス等の応
用には必須であり、本発明の工業的価値は大きい。EFFECTS OF THE INVENTION According to the present invention, it is possible to obtain a high-quality and high-performance thin film superconductor having a Nd 2 CuO 4 type crystal structure with good reproducibility. The production method of the present invention is indispensable for application of devices and the like using this type of substance, and the industrial value of the present invention is great.
図は本発明の一実施例において製造された薄膜超電導体
の、電気抵抗の温度依存性を示す図である。 11……還元処理前、12、13、14……600℃で２、16、52
時間処理、15……800℃で２時間処理。The figure shows the temperature dependence of the electrical resistance of the thin-film superconductor manufactured in one example of the present invention. 11 …… Before reduction treatment 12,13,14 …… 2,16,52 at 600 ℃
Time processing, 15 …… 800 ℃ 2 hours processing.
───────────────────────────────────────────────────── フロントページの続き (72)発明者 平尾 孝 大阪府門真市大字門真1006番地 松下電器 産業株式会社内 (56)参考文献 特開 平２−211678（ＪＰ，Ａ) ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Takashi Hirao 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (56) Reference JP-A-2-211678 (JP, A)
Claims (5)
（A1-xBx）2CuO4で表される複合酸化物のスパッタ蒸着
膜に対し、還元処理を施す（ここで、ＡはNd,Sm,Prのう
ちの少なくとも一種、ＢはCe,Thのうちの少なくとも一
種の元素を示す。また、ｘは、0.06≦ｘ≦0.08の範囲の
数値である）ことを特徴とする薄膜超電導体の製造方
法。1. A reduction treatment is applied to a sputter-deposited film of a complex oxide represented by (A 1-x B x ) 2 CuO 4 having a Nd 2 CuO 4 type crystal structure as a main component on a substrate ( Here, A represents at least one of Nd, Sm, and Pr, B represents at least one of Ce and Th, and x is a numerical value in the range of 0.06 ≦ x ≦ 0.08). A method of manufacturing a thin film superconductor characterized.
を有する単結晶基板を用いる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. A single crystal substrate having a perovskite type crystal structure is used as the base.
A method for producing the thin film superconductor described.
10-3気圧以上の酸素を含んだ雰囲気で、900℃〜1100℃
の温度範囲で一定時間加熱して得た蒸着膜を用いること
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. After the sputter deposition, further in the atmosphere or
900 ℃ ~ 1100 ℃ in an atmosphere containing oxygen of 10 -3 atmospheres or more
The method for producing a thin film superconductor according to claim 1, wherein a vapor-deposited film obtained by heating for a certain period of time in the temperature range is used.
素分圧10-3気圧以下の不活性ガス雰囲気で、500℃〜900
℃の温度範囲で一定時間加熱する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。4. The reduction treatment method is performed at 500 ° C. to 900 ° C. in vacuum or in an inert gas atmosphere with an oxygen partial pressure of 10 −3 atm or less.
The method for producing a thin film superconductor according to claim 1, wherein the heating is performed in a temperature range of ° C for a certain period of time.
ガスを含んだ雰囲気下にさらす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。5. The method for producing a thin film superconductor according to claim 1, wherein the reducing treatment is performed by exposing to an atmosphere containing at least fluorine gas.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP1339012A JPH07106904B2 (en) | 1989-12-26 | 1989-12-26 | Method of manufacturing thin film superconductor |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP1339012A JPH07106904B2 (en) | 1989-12-26 | 1989-12-26 | Method of manufacturing thin film superconductor |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH03197320A JPH03197320A (en) | 1991-08-28 |
| JPH07106904B2 true JPH07106904B2 (en) | 1995-11-15 |
Family
ID=18323437
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP1339012A Expired - Fee Related JPH07106904B2 (en) | 1989-12-26 | 1989-12-26 | Method of manufacturing thin film superconductor |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH07106904B2 (en) |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2785299B2 (en) * | 1989-02-10 | 1998-08-13 | ソニー株式会社 | Method for producing superconducting metal oxide material |
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1989
- 1989-12-26 JP JP1339012A patent/JPH07106904B2/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| JPH03197320A (en) | 1991-08-28 |
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