JPH03174307A - Production of oxide superconductor - Google Patents

Abstract

PURPOSE:To always obtain a homogeneous oxide superconducting film having a regulated compsn. and preventing a change of the quality or thickness with the lapse of time by irradiating plural parts of the surface of a target with laser beams when an oxide superconducting film is produced by vapor deposition with laser. CONSTITUTION:A target 3 made of an oxide superconductor or similar in compsn. to the superconductor is set in a vapor deposition chamber 1a and irradiated with laser beams generated from laser 7. By this irradiation, a surface part of the target 3 is scooped off and the generated particles are deposited on a substrate 2 set near the target 3 to produce an oxide superconductor. In this method, the target 3 is irradiated with laser beams through a condenser 9 and reflecting mirrors 8, 10, at least one among the mirrors 8, 10 and the lens 9 is tilted to the optical axis during irradiation to irradiate plural parts of the surface of the target 3 with laser beams and vapor deposition is carried out.

Description

Detailed Description of the Invention "Field of Industrial Application" This invention applies to oxide superconductors, which are being developed for applications such as superconducting magnets, superconducting power transmission, medical equipment, superconducting energy storage, and superconducting devices. Regarding the manufacturing method.

"Conventional technology" Conventionally, methods for manufacturing oxide-based superconductors include vacuum evaporation, sputtering, laser beam, MBE (
molecular beam epitaxy method), CVD method (chemical vapor deposition method)
, IVD (ion vapor deposition) and other film forming methods are known. In addition, among these various film formation methods, a vacuum film formation process is used to produce an oxide superconducting film that is homogeneous and has good superconducting properties, and the target is irradiated with energy such as heat, high-frequency plasma, or ion beam. The mainstream technology is to deposit particles ejected from a target onto a substrate.

Among these various film-forming methods, laser evaporation is attracting attention as a technique that can produce dense films and has a high film-forming rate. This laser vapor deposition method uses a target with a composition that is the same as or similar to the composition of the target oxide superconductor, irradiates the target with a laser beam to gouge out the surface of the target, and randomly bombards the evaporated particles. This is a method of manufacturing an oxide superconductor by depositing it on top of the oxide superconductor, and is known to have the following advantages over other film-forming methods.

■In conventional sputtering methods, the target composition and the composition of the produced film tend to deviate considerably, but in the laser evaporation method, there is little difference between the composition of the target used and the composition of the produced film, so the target composition can be oxidized. The superconducting film has the advantage of being easy to clean.

■a In the usual sputtering method, a processing time of about IO hours is required to produce an oxide superconducting film with a thickness of about 1 μm, but in the laser evaporation method, a process time of about IO hours is required to produce an oxide superconducting film with a thickness of about 1 μm.
This method has the advantage that an oxide superconducting film of about 100 yen can be manufactured in about 1 hour.

■In vapor deposition and sputtering methods, evaporation sources and 1!
Although it is necessary to place the electrodes etc. in a vacuum atmosphere, with the laser evaporation method, the laser light can be guided from outside the processing equipment, and the laser emitting device etc. can be installed outside the processing equipment, so the processing can be done easily! ! It is easy to maintain the inside of the chamber under a high-quality vacuum condition (it has the advantage of being easy to form a film in various gaseous atmospheres).

``Problem to be solved by the inventionJ'' However, the laser vapor deposition method has problems with oxide superffi.
When forming a conductor pattern, the constituent particles are ejected from the part of the target surface irradiated with the laser beam, and during vapor deposition, the 16 irradiated parts of the target are successively gouged out and consumed, resulting in release. target particles,
There was a problem in that the thickness of the film deposited on the substrate changed over time during film formation.

The present invention has been made to solve the above problems, and therefore provides a method for manufacturing an oxide superconductor that always has stable film quality and film thickness without causing changes in film quality and film thickness over time.
(The purpose is to

Means for Solving rsm J In order to solve the above-mentioned problem, the present invention installs an oxide superconductor or a target having a composition similar to the oxide superconductor in a vapor deposition chamber, and irradiates this target with a laser beam. In the method of manufacturing oxide superconductors by gouging out the surface of a target and depositing the generated particles on a scattering surface placed near the target, a laser beam is irradiated onto the target through a condensing lens and a reflecting mirror. Q (and at least one of the reflecting mirror and the condensing lens is tilted with respect to the optical axis during one curvature of the target surface) U
l! The vapor deposition is performed by irradiating the area with a laser beam.

``Operation'' Particles are ejected from multiple parts of the target surface, preventing local wear and tear on the target. In addition, since particles ejected from multiple parts of the target surface are deposited,
A homogeneous oxide superconductor film with a uniform composition can be obtained. Furthermore, since stable release of target particles can be maintained for a long time, stable film formation is possible, and a film with stable quality and large area can be obtained. Furthermore, since the method is a laser vapor deposition method, the film formation time is shortened and a dense oxide superconductor film can be obtained.

Embodiment j Figure 1 shows an example of an apparatus used to carry out the method of the present invention, where ■ indicates a processing chamber 4, and this processing container!
A substrate 2 and a target 3 are installed in a vapor deposition processing chamber 1a inside.

The processing container 1 is connected to the illustrated vacuum evacuation device through an exhaust hole 1b so that the inside can be evacuated.

A base 4 is provided at the bottom of the vapor deposition chamber 1a, and a substrate (substrate) 2 is installed horizontally on the top surface of the base 4, and is supported by a support plate 5 diagonally above the substrate 2. A target 3 is provided in an inclined state.

The target 3 is a sintered body of a composite oxide having a composition equivalent to or similar to that of the oxide superconductor film to be formed, or containing a large amount of components that easily escape during film formation.
Alternatively, it is formed from the bulk of an oxide superconductor. Specifically, currently known oxide superconductors with high critical temperatures include Y-Ba-Cu-0 system, B i-
9r-Ca-Cu-0 system, T IB a-Ca-Cu-
Since there are 0 series, etc., those of these series can be used as the target 3. Note that among the elements constituting the oxide superconductor, some elements have high vapor pressure and are easily scattered during vapor deposition, so when using target 3 containing such elements, use elements with high vapor pressure. It is sufficient to use a target containing more than the desired predetermined ratio.

The base 4 has a built-in heater, and can heat the substrate 2 to a desired temperature.

On the other hand, a laser emitting device 7 and a first
A reflecting mirror 8, a condensing lens 9, and a second reflecting stirrup lO are provided,
Lens light emitting device h! The target 3 can be condensed and irradiated with a laser beam generated by the laser beam 17 through a transparent window 11 attached to the Opj wall of the processing container 1 . The laser emitting device 7 is Targera! - Any laser such as YAG laser, CO laser, excimer laser, etc. may be used as long as it can eject the constituent particles from the laser. Also, the second reflector! 0 is rotatable vertically and horizontally at a predetermined angle around its central axis 10a (i.e., the first reflecting mirror 8O
For example, the second reflecting mirror is supported by a support mechanism (not shown) so that the inclination angle with respect to the optical axis of the second reflecting mirror can be changed.
0 can be tilted at a required angle in the direction shown by the arrow in FIG.

Also, a processing container! A laser emitting device 12 and a condensing lens 13 are provided above, and a laser beam is condensed and irradiated onto the substrate 2 through a transparent window 14 attached to the ceiling wall of the processing container I, so that the substrate 2 can be heated. It has become.

Next, the case where the method of the present invention is implemented using the apparatus shown in FIG. 1 will be explained.

After the substrate 2 and target 3 are set in the vapor deposition chamber Ia as shown in FIG. 1, the vapor deposition chamber Ia is evacuated. Here, if necessary, oxygen gas may be introduced into the vapor deposition processing chamber 1a to create an oxygen atmosphere in the vapor deposition processing chamber 1a. Further, the substrate 2 is heated to a desired temperature by activating the heater on the base 4 or by irradiating the substrate 2 with a laser beam from the laser emitting device y112.

Next, the laser beam generated from the laser emitting device 7 is transmitted to the first reflecting mirror 8, the condensing lens 9, the first reflecting mirror 8O, and the transparent window 1.
1 into the vapor deposition processing chamber Ia, and the surface of the target 3 is irradiated with focused light. At this time, the position of the condensing lens 9 is adjusted to focus the laser beam on the surface of the target 3. The surface portion of the target 3 irradiated with the laser beam is gouged out or evaporated to knock out constituent particles, and the particles are deposited on the substrate 2 . Since the substrate 2 on which the particles are deposited is heated, the deposited layer is heat treated simultaneously with the deposition.

If the laser beam irradiation continues for a predetermined time, target 3
Since only one portion of the surface portion of the material is gouged out in the thickness direction, there is a risk that the composition of the ejected particles may vary.

Therefore, after the laser beam has been irradiated for a predetermined period of time, the second reflecting mirror 10 is moved by several degrees to change its nodding angle. As a result of this drying, the laser beam is irradiated onto other parts of the target 3 by J+<1, so that particles can be ejected from the surface of other parts of the target 3 and deposited on the substrate 2. Thereafter, the irradiation position of the laser beam on the target 3 is changed at predetermined time intervals to sequentially knock out the particles, thereby depositing the particles on the substrate 2.

In this way, by appropriately changing the irradiation position of the laser beam, particles from various parts of the surface of the target 3 can be ejected, so that particles of a uniform composition can always be ejected from the surface part of the target 3.

The particles ejected in this way are in a sufficiently activated state, and therefore are densely deposited on the substrate 2. The deposited film is heated by the heater on the base 4 or by a laser beam to form the hot part p1, so that an excellent oxide superconducting film with a dense and well-organized crystal structure can be obtained.

By the way, in the embodiment described above, the irradiation position of the laser beam on the target 3 was changed by tilting the first reflecting mirror 8O, but the first reflecting mirror 8, the condensing lens 9, and the second reflecting mirror IO are small. The position of the laser beam 1 (a) can also be changed by tilting both of them with respect to the optical axis.Also, when irradiating the target 3 with the laser beam,
Film formation may be performed by vibrating the target 3 at a constant cycle and uniformly irradiating the entire surface of the target 3 with the laser beam.

Note that, as shown by the two-dot chain line in FIG.
If the tape-shaped base material sent out from the base material is sent to the base 4 and then taken up by the take-up roller 2I for vapor deposition, it is possible to deposit the oxide superconductor film on the long base material. It is possible to manufacture a superconducting conductor having

When manufacturing the long superconducting conductor, the second reflecting mirror IO is deposited at an angle in the same way as in the above case, so that a film of the oxide superconductor is uniform in thickness and quality over the entire length of the long base material. It is possible to manufacture a superconducting conductor having the following properties.

"Manufacturing Example" Using a vapor deposition apparatus with the configuration shown in Figure 1, 5rT was used as the substrate.
Made by iOS, length 10II+m, fl 10111 thickness 0
．． 51 substrate was used, and Y was used as the target.
A disk-shaped target made of an oxide superconductor having the following compositions: o, s13 a+, mc uso t-6 was used. In addition, the inside of the vapor deposition processing chamber was evacuated to 10'' Torr1.
Laser deposition was performed while heating the substrate to 640°C. The laser beam for target heat radiation uses Ar with a wavelength of 193 nm.
l;' A laser was used.

The critical temperature of the obtained oxide superconductor was measured, and the critical current density was measured after cooling with liquid nitrogen.

Critical temperature 88 K Critical current density 2 x 10'A/am" (77K,
By carrying out the method of the present invention as described above, it was possible to obtain an oxide superconductor exhibiting excellent critical temperature and critical current density.

"Effects of the Invention" As explained above, the present invention irradiates a plurality of parts of the target surface with a laser beam to knock out particles from the plurality of parts of the target surface, thereby forming an oxide superconductor film on a base material. , it is possible to form a uniform and dense oxide superconductor film while preventing local wear on the target surface.

In addition, since the laser beam is applied to multiple parts of the target, the target particles can be emitted stably at all times, which has the effect of allowing stable film formation over a long period of time.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram showing an example of a laser vapor deposition apparatus suitable for use in carrying out the method of the present invention. ■... Location 4, Ia... Vapor deposition processing chamber! b...
Exhaust hole, 2... substrate, 3... target, 4...
Base, 5... Support plate, 7.12... Laser emitting device, 8... First antimoon (armor, 9.13... Condensing lens,
10...Second reflection boundary, It. +4...Transparent window.

Claims (1)

[Claims] An oxide superconductor or a target having a composition similar to that of the oxide superconductor is installed in a vapor deposition chamber, and the target is irradiated with a laser beam to gouge out the surface of the target to remove the generated particles. In a method of manufacturing oxide superconductors by depositing them on a substrate placed near a target, a laser beam is irradiated onto the target via a condensing lens and a reflective mirror, and during irradiation, the reflective mirror and condensing lens are 1. A method for producing an oxide superconductor, characterized in that vapor deposition is performed by irradiating a plurality of portions of the surface of a target with a laser beam while at least one of the laser beams is tilted with respect to an optical axis.