JPH03174306A - Production of oxide superconductor - Google Patents

Abstract

PURPOSE:To form a film of an oxide superconductor having stable quality and thickness over the wide range of the surface of a substrate by swinging a target during irradiation 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 swung in at least one of perpendicular, transverse and oblique directions during irradiation with laser beams and a film of the oxide superconductor is formed.

Description

[Detailed Description of the Invention] "Industrial Application Field" This invention is applicable to superconducting magnets, superconducting power transmission, medical i
This invention relates to a method for manufacturing oxide superconductors, which are currently being developed for applications such as superconducting energy storage and superconducting devices.

"Conventional technology" Conventionally, methods for producing oxide-based superconductors include vacuum evaporation, sputtering, laser evaporation, and MIl (
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 forming methods, a vacuum film forming process is used as a method for manufacturing an oxide superconducting film that is homogeneous and has good superconducting properties, and Jl< The mainstream technology is to deposit particles ejected from a target by a single shot 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 scoop out the surface part of the target, and deposits the particles onto the base material. This is a method of manufacturing oxide superconductors by deposition, and is known to have the following advantages compared to other film formation methods.

■ In normal sputtering methods, there is a region where the composition of the target and the composition of the produced film are quite different, or in laser evaporation method, there is a small difference between the composition of the target used and the composition of the produced film, so the oxide of the desired composition can be produced. This has the advantage that it is easy to obtain superconducting films.

■In the normal sputtering method, a processing time of about 11 fJ at IO is required to produce an oxide superconducting film with a thickness of about 1 μm, but in the laser evaporation method, an oxide superconducting film with a thickness of about several μm is required. This method has the advantage that a superconducting film can be manufactured in about one hour.

■In the evaporation method and sputtering method, it is necessary to place the evaporation source and electrodes in a vacuum atmosphere, but with the laser notation method, the laser beam can be guided from outside the processing equipment, and the laser emitting device etc. can be provided outside the processing apparatus, so it is easy to maintain a high-quality vacuum condition inside the processing apparatus, and there is an advantage that films can be formed in various gaseous atmospheres.

"Problem to be Solved by the Invention" When forming an oxide superconductor film on a substrate using the laser vapor deposition method described above, a laser beam is focused on one spot on the target surface to knock out particles from that spot. As a result, the ejected particles spread out radially from the target, diffuse, approach the base H, collide with the surface of the base material, and are deposited. Therefore, on the base material surface f, there is a difference in the number of particles deposited on a part far from the target and a part close to the target, which causes a problem of causing non-uniformity in the quality and thickness of the film formed on the base material.

When the film quality and thickness become non-uniform, there is a problem that a film with excellent superconducting properties can only be formed in a narrow range on the board.

The present invention was made to solve the above problems, and it is possible to form an oxide superconductor pattern with stable film quality and thickness over a wide range of the surface of a base material. The purpose is to provide a way to send money.

"Means for Solving the Problems" In order to solve the problems described above, 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 part of the target and depositing the generated particles on a base material placed near the target, the target is irradiated with a laser beam in the vertical and horizontal directions. The film is formed by moving the bridge in at least one of the direction and the diagonal direction.

"Function" When forming a film by irradiating the target with a laser beam, by rotating the target, the flow of particles ejected from the target can be distributed over a wide range of the base material surface and deposited on the base material. An oxide superconductor film with a uniform thickness and quality is formed on the top of the Go board.In addition, the particles ejected from the target are deposited over a wide area on the board, resulting in a film with a uniform thickness and quality. A large-area oxide superconductor film can be produced.Furthermore, since the film is formed by laser evaporation, the film formation time is shortened and a dense oxide superconductor film is produced.

"Example" Fig. 1 shows an example of the apparatus used to carry out the method of the present invention, where ■ indicates the 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 chamber "a1" is connected to a vacuum evacuation device (not shown) via 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. 3 targets (installed in an inclined position).

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 are easily evacuated 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-13a-Cu-0 series, B1-9
r-Ca-Cu-0 system, T I-na-Ca-Cu
Since there are -0 series, etc., those of these series can be used as the target 3. Note that the oxide surface rr
Among the elements that make up the i-conductor, some elements have high vapor pressure and are easily scattered during vapor deposition. A target containing more than a predetermined ratio may be used.

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

The support plate 5 passes through its central portion and is tilted at a required angle (for example, 900 degrees
) It is rotatably supported. The support plate 5 can be slid at a constant speed or intermittently about the central axis 5a by a drive device such as a motor (not shown) installed near the support plate 5.

On the other hand, on the side of the processing container 1, a laser emitting device 7 and a first
A reflection 1B, a condensing lens 9, and a second reflection mirror 10 are provided,
The laser beam generated by the laser emitting device 7 is transmitted through a transparent window attached to the side wall of the processing container l! It is possible to irradiate the target 3 with focused light through the lens 1. As the laser emitting device 7, any device such as a YAG laser, a CO laser, an excimer laser, etc. may be used as long as it can eject constituent particles from the target 3.

Also, above the processing container 1 is a laser emitting device 12 and a condensing lens! 3 is provided so that the substrate 2 can be heated by concentrating a laser beam on the substrate 2 through a transparent window 14 attached to the ceiling wall of the processing chamber 41.

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 la as shown in FIG. 1, the vapor deposition chamber la 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. Also, operate the heater on the base 4, or operate the laser emitting device! 2 irradiates the substrate 2 with a laser beam to heat the substrate 2 to a desired temperature.

Next, the laser beam generated from the laser emitting device 7 is guided into the vapor deposition chamber la through the first reflecting mirror 8, the condensing lens 9, the second reflecting mirror 10, and the transparent window II, and is directed onto the surface of the target 3. Emits 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 of the target 3 irradiated with the radar 1 beam is gouged out or evaporated to knock out its constituent particles, which spread radially and scatter as shown by the R1 line in FIG. deposits on the surface of During this deposition, the support plate 5 is moved by the arrow a shown in FIG.
Go back and forth at a predetermined speed in the direction! Coordinate dispatch. Then, the particles ejected from the target 3 spread over a wider range and reach the surface of the base material 2. By forming a film on the base material 2 while expanding the spread of the particles in this way, the particles can be deposited uniformly over a wide range of the surface of the base material 2, so that the film can be deposited on the base material 2 with uniform thickness and quality. Can form a deposited layer.

Note that the rolling motion of the target 3 may be continuous or intermittent. Furthermore, the amplitude when retracting the target 3 is such that the particles generated from the target 3 are transferred to the substrate 2.
It is necessary to be able to reach all surfaces uniformly.

Since the substrate 2 on which the particles are deposited is heated as described above, the deposited film is heat-treated at the same time as the deposition. Therefore, an oxide superconductor can be obtained by forming an oxide superconductor film on the base material after heat treatment.If the heat treatment is not sufficient, heat treatment may be performed separately after the vapor deposition, and the produced oxide superconductor The crystal structure of the body's membranes may be adjusted.

Moreover, since the particles ejected from the target 3 as described above are in a sufficiently activated state, they are densely deposited on the substrate 2. Furthermore, since the deposited film is heat-treated, an oxide superconductor film with a dense, well-organized crystal structure and excellent superconducting properties can be obtained.

By the way, as shown by the two-dot chain line in FIG. 1, a delivery roller 20 and a take-up roller 21 are provided on the left and right sides of the base 4, and the tape-shaped base material sent out from the delivery roller 20 is sent to the base 4 and taken up. If laser vapor deposition is performed while winding with the roller 2I, a superconducting conductor having a pattern of an oxide superconductor can be manufactured on a long base material.

When manufacturing the long superconducting conductor, a film of oxide superconductor with good properties is formed over the entire length of the long base material by vapor deposition while swinging the target 3 as in the case described above. be able to.

Further, by discharging one target 3, an oxide superconductor film having a uniform thickness and composition can be generated on the entire surface of a wide tape-shaped base material.

By the way, in the embodiment described above, an example in which the target 3 is swung in the direction of the arrow a in the drawings has been described, but the swiveling direction of the target 3 is not limited to the direction of the arrow a, but may be any of the left, right, up, down, or diagonal directions.

"Manufacturing Example" Using a vapor deposition apparatus configured as shown in Fig. 1, S r
Made by Tio, length 1 (1+a, width 10am, thickness 0.
A 51 m1 substrate was used, and Y was used as a target.
o, mBa+, sc uso? A disk-shaped target made of an oxide superconductor having a composition of -5 was used. Also,
The inside of the vapor deposition chamber is heated to 10°' Torr1. : Laser deposition was performed while exhausting the air and heating the substrate to 640°C. The laser beam for target irradiation uses ArF with a wavelength of 193 nm.
A laser was used. Further, during film formation, the film formation process was carried out while the target was oscillated in the direction of arrow a in FIG. 1 at a cycle of ±45° 1087 times.

Through the above treatment, an oxide superconductor in which a 1.0 μm thick oxide superconductor film was formed on the substrate could be obtained.

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. Oxl O'A/am", (77,
OT) By implementing the method of the present invention as described above, an oxide superconductor exhibiting excellent critical temperature and critical current density could be obtained.

"Effects of the Invention" As explained above, the present invention provides the following advantages when depositing an oxide superconductor film on a substrate by irradiating the target with a laser beam to knock out particles on the surface of the target. Since the target is oscillated, all the particles can be fully collided and deposited over a wide range of the target surface, forming a dense oxide superconductor film with uniform thickness and quality over a wide range of the base material. There is an effect that can be done.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram showing an example of a laser evaporation apparatus suitable for carrying out the method of the present invention, and FIG. 2 is an explanatory diagram showing the positional relationship between a target and a substrate. 1... Processing container exchange, 11... Vapor deposition processing chamber, tb... Exhaust hole, 2... Substrate, 3... Target, 4... Base, 5... Support plate, 7. 12... Laser emitting device,
8... First reflecting mirror, 9.13... Condensing lens, IO
...Second reflecting mirror, 11°14...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 base material placed near a target, the target being irradiated with a laser beam is oscillated in at least one of the vertical, horizontal, and diagonal directions. A method for producing an oxide superconductor characterized by forming a film.