Superconductor technology: apparatus – material – process – High temperature – per se – Having tc greater than or equal to 150 k
Patent
1989-11-16
1992-10-27
Lusignan, Michael
Superconductor technology: apparatus, material, process
High temperature , per se
Having tc greater than or equal to 150 k
505732, 505731, 505730, 427 62, 427529, 427524, 427576, 427580, 427572, 427584, 427596, 20419224, B05D 512, B05D 306
Patent
active
051589311
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a method for manufacturing an oxide superconductor thin film as a high-temperature superconductor.
BACKGROUND ART
Conventionally, oxide superconductors including a high-temperature superconductor, such as a Y-Ba-Cu-O system superconductor, are prepared by either thoroughly blending together powdered materials in a proper blend ratio (e.g. Y:Ba:Cu=1:2:3), sintering a resultant blend at high temperature and holding it at high temperature in an oxygen atmosphere or blending together powdered materials and sintering a blend directly at high temperature in an oxygen atmosphere. The oxide superconductor thus manufactured is usually block-like in configuration. In practical application, the oxide superconductor needs to be formed into a wire, a ribbon, a thin film, an element and so on. However, it is substantially not possible to form these products from the aforementioned block-like unit.
In the formation of the ribbon, thin film and element, it is necessary to form a superconductive film on a substrate. This thin-film forming technique includes a plasma CVD, a thermal CVD, a sputtering, laser sputtering, and a technique for coating a slurry, that is a mixture of row materials with a solvent such as water, on a substrate. Various attempts have been made to apply the thin-film forming technique to, for example, various elements. For example, J. Narayan et al. Appl. Phys. Lett. 51(22) PP. 1845(1987) and D. Dijkkamp et al. Appl. Phys. Lett. 51(8) PP 619(1987) disclose a method for forming an oxide superconductor by a laser sputtering in a vacuum atmosphere. In this method, it is necessary to, subsequent to forming a thin film on a substrate, heat-treat it at a temperature as high as above 800.degree. C. in an oxygen atmosphere so that oxygen may be incorporated into a resultant crystal structure. However, there is a risk that the substrate prepared will be broken or oxidized so that it cannot be used in a practical application. Other thin-film forming methods also involves this problem, thus restricting the use of the substrate material in the formation of an oxide superconductor thin film. For example, an epoxy substrate for interconnection, an aluminum ribbon, a semiconductor substrate and an element-formed silicon substrate, upon being exposed to a high-temperature oxygen atmosphere, cannot be employed, failing to prepare an oxide superconductor thin film.
Forming an oxide superconductor thin film on a substrate, if possible, will find an extended application range for the oxide superconductor and offer a step forward to a further practical application.
DISCLOSURE OF THE INVENTION
It is accordingly the object of the present invention to provide a method for forming an oxide superconductor thin film on any substrate available.
A present method for forming a superconductor thin film on a substrate comprises the steps of preparing a substrate, depositing an oxide superconductor thin film on the substrate and supplying excited oxygen to or near a thin film deposition site on the substrate.
According to the present invention, since the excited oxygen is supplied to or near the thin film deposition site on the substrate, an adequate amount of oxygen is incorporated in the thin film deposited. It is, therefore, not necessary to expose the thin film and substrate to an oxygen atmosphere at high temperature. Thus a better oxide superconductor thin film can be formed on the substrate regardless of the kinds of substrates.
BRIEF DESCRIPTION OF THE DRAWINGS
FIGS. 1,2,3,4,5,6,7,8,9,10,11 to 12 are diagrammatic views, each, showing an apparatus for carrying out a method of the present invention.
BEST MODE OF CARRYING OUT THE INVENTION
The present invention will be explained below in more detail.
According to the method of the present invention, an oxide superconductor thin film is deposited on a substrate by supplying activated oxygen toward the thin film deposition site or its neighborhood.
The oxide superconductor thin film may be formed with any conventional ox
REFERENCES:
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patent: 5039657 (1991-08-01), Goldman et al.
Terashima et al., "Single-Crystal YBa.sub.2 Cu.sub.3 O.sub.7-x Thin Films by activated Reactive Evaporation", Jpn. J. Appl. Phys. 27(1) Jan. 1988 L91-93.
S. Witanachchi et al., "Deposition of superconducting Y-Ba-Cu-O films at 400.degree. C. without post-annealing", Appl. Phys. Lett. 53(3), Jul. 18, 1988.
Jpn. J. Appl. Phys., vol. 26, No. 7, Jul. 1987, Synthesis of Y-Ba-Cu-O Thin Films on Sapphire Substrates by FR Magnetron Sputtering, pp. L1199-L1201.
Denki Joho Tsushin Gakkai Gijutsu Kenkyu Hokoku, vol. 87, No. 137, SCE87-20 [Sankabutsu Ceramics Superconductor Thin Film no Sputtering-ho niyoru Sakusei] pp. 49-54.
Applied Physics Letter 52(9) pp. 754-756, X. D. Wu, et al., Feb. 1988 "Low-temperature preparation of high T.sub.c superconducting thin films".
Applied Physics Letter, 52(4), pp. 320-322, L. Lynds, et al., Jan. 1988, "Superconducting thin films of Y-Ba-Cu-O produced by neodymium:yttrium".
Applied Physics Letter, 51(8), pp. 619-621, D. Dijkkamp et al., Aug. 1987, "Preparation of Y-Ba-Cu oxide superconductor thin films using pulsed laser evaporation from high T.sub.c bulk material".
Hayashi Kazuo
Morimiya Osami
Noda Etsuo
Suzuki Setsuo
Kabushiki Kaisha Toshiba
King Roy V.
Lusignan Michael
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