JPH02139810A - Manufacture of superconductor - Google Patents

Abstract

PURPOSE:To provide possibility of fabricating a superconductor through low temp. heat treatment by irradiating a beam of light including a wavelength capable of absorbing, dissolving, and energizing the gas of the atmosphere containing oxygen to a layer coated with a composite oxide ceramic layer under such an atmosphere as mentioned, and heightening the pressure of the atmosphere gas than the open air pressure when treatment is performed. CONSTITUTION:To perform heat treatment by irradiating ultraviolet rays, a vessel 11 capable of shutting air in satisfactory performance is provided with an exhaust hole 13 and a lead-in hole 12 for gas including N2O and oxygen such as O2, and heat treatment is made under a pressure higher than the open air pressure. Light from a light source 14 generating ultraviolet rays l such as an eximer laser beam source is led in from a light lead-in window 15. If ultraviolet rays l are irradiated on the surface of a based board 16 coated with composite oxide ceramic such as YBCO, the base board 16 is heated, and N2O gas is dissolved to generate active oxygen, and the surface of base board 16 becomes oxidative atmosphere. A superconductive film 20 becomes a heat treated portion 22 except the part 23 where no light ingresses in the base board 21 and is not subjected to heat treatment. The heat treating temp. can be lowered to 400-700 deg.C from the conventional 800-900 deg.C.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention mainly relates to a method of manufacturing a superconducting film, which is used to construct an electric circuit or an electronic circuit, by disposing a superconducting material on a substrate.

Conventional technology Conventionally, high-temperature superconductors have been produced by mixing powders of, for example, yttrium oxide, barium carbonate, copper oxide, etc., press-forming them into a solid, and then firing them at a high temperature of 900"C or higher. Ever since it was discovered that this material becomes superconducting at high temperatures, it has been expected to be used in a wide range of applications as circuit boards by forming films on substrates.

Problems to be Solved by the Invention However, with these conventional techniques, if these high-temperature superconductors are to be applied to, for example, printed circuit boards for the wiring of electric or electronic circuits, it is difficult to adjust the shape of the wiring pattern by using the above-mentioned superconductors. After processing, the same 90
Heat treatment must be performed at a high temperature of 0'C or higher. For this purpose, a substrate must be used that can withstand high-temperature heat treatment. Moreover, in order to function as a high-temperature superconductor, for example, a YBCuO film (yttrium-barium-copper-oxygen film) with good crystallinity must be formed, so the substrate must necessarily be sapphire, T4i crystal silicon, or gallium arsenide. It was necessary to use expensive substrates such as In an attempt to solve this problem, attempts have been made to lower the temperature of the heat treatment by applying an electric field to oxygen gas in a reduced pressure atmosphere of oxygen gas and performing heat treatment in a plasma state to sufficiently oxidize. However, in this method, the heat treatment of the film is carried out at atmospheric pressure or reduced pressure, so that the oxidized material releases oxygen again at high temperatures, and oxygen is not fully bonded in some parts. In the present invention, as a result, the critical current and transition temperature were not improved, or even if they were improved, the effect was small, or even the effect was not sustainable. aims to solve such problems.

Means for Solving the Problems In the present invention, in order to solve the above-mentioned problems, superconductors, which were conventionally heated as a whole at 900°C in a heating furnace, are heated in an oxygen-containing gas atmosphere. By pressurizing the gas atmosphere to above atmospheric pressure and irradiating it with intense light with a very short wavelength, we provide a technology that enables the production of high-quality superconducting composite oxide crystal films through heat treatment at relatively low temperatures. .

Effects The effects of the present invention produced by using the above-mentioned means are as follows.

First, in the conventional method, the heat treatment of the film was carried out at atmospheric pressure or reduced pressure, so the oxidized material releases oxygen again at high temperatures, and oxygen is not fully bonded in some parts. As a result, the critical current and transition temperature were not improved, or even if they were improved, the effect was small, or the effect was not sustainable. In the present invention, this is an effect of oxygenation in an atmosphere that eliminates the above-mentioned re-release of oxygen. Second, in that state, by generating oxygen atoms or oxygen molecules that are in a radical state, the radicals and oxygen molecules collide again, and although the excitation energy they each have is small, they turn into radicals in R1, so the necessary The effect is that sufficient oxidation can be performed by heating. Thirdly, by increasing the pressure of the oxygen-containing gas, the light irradiated onto the gas is efficiently absorbed by the gas.
This has the effect of increasing the generation of oxygen radicals and ensuring sufficient oxidation.

EXAMPLES Below, typical examples of the present invention will be shown based on the drawings. FIG. 1 is a schematic diagram of an apparatus for irradiating ultraviolet light and performing heat treatment to carry out the present invention.

11 is a container that can sufficiently block air, and 12 is a container with N20
, 02, etc. are the inlet ports for oxygen-containing gases, and 13 are the outlet ports for these gases, which are evacuated with a pump if necessary. do. 14 is a light source that generates ultraviolet light 9, for example, an excimer laser light source or the like is used. ] 5 is a light introduction window. 16 is a base coated with a composite oxide ceramic such as YBCO, and ultraviolet light 2 is irradiated from the light source 14 to the substrate surface through the window 15. At this time, the ultraviolet light Ω heats the very surface of the substrate, decomposes N 20 on the way, generates oxygen radicals, and creates an active oxidizing atmosphere on the film surface. FIG. 2 is formed according to the present invention.
This is a superconducting film 20. 21 is a substrate, 22 is a portion that has been heat-treated by light irradiation, and 23 is a portion that is not exposed to light and has not been heat-treated. As a result, the heat treatment temperature itself is lower than the conventional 800-900'C.
We were able to lower the temperature from 400 to 700″C.

In this example, an example of a composite oxide of yttrium, barium, and copper was explained, but when erbium (Er) is used instead of yttrium, or a composite oxide of lanthanum, strontium, and copper is used, Furthermore, it goes without saying that it is also effective for complex oxides of bismuth, strontium, calcium, and copper, as well as complex oxides of thallium, styronium, calcium, and copper.

Effect of the invention The effects of the present invention are as follows.

First of all, whereas heat treatment was performed on the entire film at a high temperature of 800 to 900°C, in the present invention, only a very small surface is heated, but the entire heat treatment atmosphere can be lowered to 400 to 700°C. Therefore, a relatively inexpensive substrate such as glass can be used as the substrate.

The second effect is that in the conventional method, heat treatment was performed in an 02 atmosphere to prevent the loss of oxygen in the oxide during heat treatment, but in this heating, 02 is decomposed into an active state. By irradiating this oxygen-containing gas with ultraviolet light, the very surface of the oxygen-containing gas is heated in the active oxygen radicals, so that the oxygen-deficient state can be improved. It is possible to obtain a superconducting ceramic film with excellent crystallinity through heat treatment without heat treatment, and it is extremely useful for application to printed circuit boards and superconducting elements.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of an apparatus for irradiating ultraviolet light in an oxygen-containing atmosphere to carry out the present invention, and FIG. 2 is a cross-sectional view of the structure of an example of a superconducting film realized by the present invention. 11...Device container, 12...Gas inlet, 13...
- Gas exhaust port, 14... Ultraviolet light source, 15... Light introduction window, 16... Substrate, 21... Substrate, 22... Heat-treated composite oxide, ceramic film, 23...・・・
Composite oxide ceramic membrane that is not heat treated.

Claims (4)

[Claims] (1) When processing the layer coated with the composite oxide ceramic layer by irradiating it with light containing a wavelength that can absorb and decompose and excite at least oxygen-containing gas in an oxygen-containing gas atmosphere, an oxygen-containing atmospheric gas A method for producing a superconducting film, the method comprising: increasing the pressure of the film to at least higher than atmospheric pressure. (2) The method for manufacturing a superconducting film according to claim 1, characterized in that N_2O, O_2 gas, or a mixed gas thereof is used as the oxygen-containing gas. (3) The method for producing a superconducting film according to claim 1, characterized in that an excimer laser is used as the ultraviolet light source. (4) The method for producing a superconducting film according to claim 1, characterized in that visible or infrared light is also irradiated at the same time as the ultraviolet light is irradiated.