JP3299769B2 - Superconductor manufacturing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a superconducting magnet,
The present invention relates to a method for manufacturing a superconductor which is being applied to superconducting power transmission, medical equipment, superconducting energy storage, superconducting elements, and the like.

[0002]

2. Description of the Related Art Conventionally, as a method of manufacturing a superconductor,
Vacuum evaporation method, sputtering method, laser evaporation method, MBE
There are known film forming methods such as a molecular beam epitaxy (CVD) method, a chemical vapor deposition (CVD) method, and an ion vapor deposition (IVD) method. In addition, as a method for producing a superconducting film having a uniform and good superconducting property in these various film forming methods,
2. Description of the Related Art A technique in which a target is irradiated with energy such as heat or high-frequency plasma or an ion beam by using a vacuum process to deposit particles hit from the target on a substrate has become mainstream.

In such various film forming methods, a laser vapor deposition method has attracted attention as a technique capable of forming a dense film and having a high film forming speed. This laser deposition method uses a target with the same or similar composition as the target superconductor composition, irradiates the target with a laser beam, cuts through the surface of the target, and deposits the generated particles on the substrate. This is a method of manufacturing a superconductor by depositing, and is known to have advantages described below as compared with other film forming methods.

In the ordinary sputtering method, the composition of the target film and the composition of the formed film tend to be considerably different from each other. However, in the laser deposition method, since the deviation between the composition of the target used and the composition of the formed film is small, the desired composition of the target film cannot be obtained. There is an advantage that a superconducting thin film can be easily obtained.

In the ordinary sputtering method, a processing time of about 10 hours is required to produce a superconducting film having a thickness of about 1 μm. In a laser vapor deposition method, a superconducting thin film having a thickness of about several μm is required to be about 1 μm. There is an advantage that it can be manufactured in about time.

In the vapor deposition method and the sputtering method,
It is necessary to place the evaporation source and electrodes in a vacuum atmosphere.However, in the laser evaporation method, laser light can be guided from outside the processing apparatus, and a laser oscillation apparatus can be provided outside the processing apparatus. Further, there is an advantage that the inside of the processing apparatus can be easily maintained in a high vacuum condition or an oxidizing atmosphere, and a film can be formed in various gaseous atmospheres.

[0007]

However, when a superconducting thin film is formed on a substrate by the above-described laser vapor deposition method, the constituent particles are beaten out from a portion of the target surface irradiated with the laser beam while vapor deposition is performed. In addition, there is a problem that the laser beam irradiated portion on the target surface is sequentially cut off and is intensively consumed. As a result, the energy density of the laser beam irradiated on the target changes between immediately after the start of the laser beam irradiation and after a certain period of time after the irradiation, so that the amount of the target particles emitted and the amount of the target particles deposited on the base material are changed. There is a problem that the quality and thickness of the film change with time during the film formation.

Further, when a superconducting thin film is formed directly on a substrate, there is a problem that the superconducting properties of the superconducting thin film are deteriorated because, for example, the constituent elements of the substrate react with the constituent elements of the superconducting thin film. Therefore, conventionally, for the purpose of solving the above problem,
Means of forming an intermediate layer having a composition that does not easily react with a superconducting thin film on a base material and forming a superconducting thin film on the intermediate layer have been widely adopted. Specifically, as the intermediate layer, a layer made of SrTiO ₃ , MgO, or partially stabilized zirconia such as YSZ is used.
These intermediate layers play a role in preventing element diffusion between the metal substrate and the superconducting thin film.

By the way, in order to form an intermediate layer on a substrate by using the laser vapor deposition apparatus, after forming the intermediate layer on the substrate inside the vacuum vessel, the target is replaced or the substrate is separated. It was necessary to transfer to a vacuum container and form a superconducting thin film. This is due to the fact that only one target can be installed in the laser deposition apparatus.

When the above-described method is performed, a plurality of steps such as installation of a substrate, evacuation and heating of the substrate must be performed twice. Then, when removing the base material with the intermediate layer from the vacuum container, there is a problem that fine dust adheres to the intermediate layer or the base material, and the base material and the intermediate layer are damaged due to improper handling. There was a risk of doing it.

The present invention has been made in view of the above circumstances,
The target can be irradiated with the laser beam for a long time and continuously, and the intermediate layer and the superconducting thin film having a uniform composition and a uniform film thickness can be formed on the substrate. It is an object of the present invention to provide a method capable of forming two or more layers on a substrate without breaking its vacuum state inside.

[0012]

According to a first aspect of the present invention, there is provided a chamber for accommodating a target, a substrate, and a base, and an oscillation of a laser beam for irradiating the target with a laser beam. A device and a target setting means for setting the target at a position where the laser beam emitted from the oscillation device is irradiated on the target surface, wherein the target setting means has a disk shape and is provided on one surface thereof. Using a laser deposition apparatus including a target setting disk in which a plurality of disk-shaped targets are arranged along the circumferential direction, and a rotating means for rotating the target setting disk, a long base is used for the base. A method for producing a superconductor in which an intermediate layer and a superconducting thin film are laminated on a substrate by continuously supplying a material, wherein the target installation disk is used for forming an intermediate layer. A plurality of first targets and a plurality of second targets for forming a superconducting thin film are provided, respectively, and a laser beam is first irradiated on one of the first targets for a predetermined time, and then the installation disk is rotated to apply a laser beam to another first target. After forming the intermediate layer on the substrate by performing the process of forming the intermediate layer by irradiating the required number of times, the laser beam is irradiated to one of the second targets for a predetermined time by rotating the installation disk,
Thereafter, a process of irradiating a laser beam to another second target by rotating the installation disk is performed a plurality of times to form a superconducting thin film on the intermediate layer.

[0013]

As described above, if the laser deposition apparatus according to the present invention is used, a plurality of targets can be sequentially irradiated with a laser beam to form a continuous film. Even after a lapse of time, the energy density of the laser beam irradiated on the target is almost constant, and the amount of target particles emitted during the laser beam irradiation and the quality and thickness of the film deposited on the base material are It is always constant during the film forming operation.

Further, if a plurality of first targets for the intermediate layer and a plurality of second targets for the superconducting thin film are mounted on the target installation disk, and these are sequentially used to form a film,
The intermediate layer and the superconducting layer are continuously formed on the substrate without breaking the vacuum state of the vacuum chamber. Also, once the base material is placed in the vacuum chamber, the vacuum state of the vacuum chamber does not need to be broken until the formation of the intermediate layer and the superconducting thin film is completed. Nor.

[0015]

The present invention will be described below in detail with reference to examples. 1 to 3 are views showing an example of a laser vapor deposition apparatus used for carrying out the present invention. In the drawings, reference numeral 1 denotes a laser vapor deposition apparatus, and the laser vapor deposition apparatus 1 has a vapor deposition processing chamber 2 and a target setting mechanism 3 And a laser oscillation device 4 and a vacuum pump 5.

In the vapor deposition chamber 2, a substrate 7 is installed supported by a horizontal base 6, and a heater for heating the substrate 7 is built in the base 6. The material 7 can be heated to a desired temperature. Although not shown in FIG. 1, the base material 7 is in a tape shape, and a tape material sending device and a winding device are connected to the vapor deposition processing chamber 2. The tape-shaped substrate can be continuously supplied.

Above the substrate 7, a deposition chamber 2 is provided.
The target installation mechanism 3 is installed through the ceiling of the
On the target orbiting disk 8 of the target setting mechanism 3, ten target rotating disks 9 are installed along the circumference at intervals of 36 degrees. Further, a disk-shaped target 10 is attached to each target rotating disk 9, and one of the ten disk-shaped targets 10 faces the base material 7. Of these targets 10, as shown in FIG. 3, the right five are the first targets 10a for forming the intermediate layer, and the other five are the targets 10b for forming the superconducting thin film.

Specifically, as the first target 10a,
A plate-like target made of SrTiO ₃ or MgO or a plate-like target made of stabilized zirconia such as YSZ is used. Specifically, as the second target 10b, a sintered body of a composite oxide containing the same or similar composition as the superconducting film to be formed on the base material 7, or containing many components that easily escape during film formation, Alternatively, an oxide superconductor bulk or the like can be used. For example, YBaCuO-based, BiSrCaCuO-based, Tl
A disk-shaped material such as BaCaCuO is used as the second target 10b.

In this embodiment, as shown in FIG. 3, a target orbiting disk 8 having a configuration in which five targets 10a and five targets 10b are arranged is used. However, as shown in FIG. The method of the present invention may be performed using the target revolving disks 8 arranged one by one. In this case, the revolving angle of the target revolving disk 8 is adjusted and the target 10
After setting the revolution angle so that only the laser beam can be irradiated with the laser beam, forming the intermediate layer, irradiating the target 10b with the laser beam, and then setting the revolution angle so that only the target 10b can be irradiated with the laser beam. Good.

A laser oscillating device 4 is provided on the side of the evaporation processing chamber 2, and a laser beam R emitted from the laser oscillating device 4 is applied to one disk-shaped target 10 via a condenser lens 11. It is designed to be irradiated. The laser oscillation device 4 used here may be any device that can generate constituent particles from the target 10, but a high-output laser such as a YAG laser, a CO ₂ laser, an excimer laser, or the like is preferable. Used for

As shown in FIG. 2, the target installation mechanism 3 includes a target revolving disk 8, a target rotating disk 9, and a target 10 disposed in the evaporation processing chamber 2 (in a vacuum atmosphere). The target revolving motor 12 and the target rotation motor 13 are provided.

A gear A is fixed to the rotating shaft of the target revolving motor 12, and this gear A is attached to one end of the main shaft 14 and meshes with a gear B having this as a rotating shaft. A target revolving disk 8 is coaxially attached to the other end of the main shaft 14 to which the gear B is attached. Therefore, the rotational force of the target revolving motor 12 is transmitted to the main shaft 14 via the gear A and the gear B, and rotates (revolves) the target revolving disk 8 disposed in the vapor deposition processing chamber 2.

When the main switch is turned on, the target revolving motor 12 rotates the target revolving disk 8 by a predetermined angle (for example, 36 degrees). Immediately thereafter, the sub-switch is automatically turned off to stop the rotation. After a lapse of a predetermined time, the sub-switch is turned on again and the same operation as described above is repeated. The gear B has 1
The zero stopper pin hole 15 is penetrated, and when the target revolution motor 12 is stopped, the stopper pin 16 installed near the gear B is inserted into one of the ten stopper pin holes 15 and the gear is inserted. The rotation of the main shaft 14, which is the rotation axis of B, is fixed, so that the rotation play of the target revolution disk 8 is eliminated.

A gear C is fixed to a rotating shaft 17 of the target rotation motor 13, and the gear C is
A gear E, which is coaxial with the gear D and is mounted on the other end of the rotating shaft 18 and is disposed in the vapor deposition chamber 2, meshes with a gear F.
Further, this gear F meshes with one end of an adjacent shaft gear G. A gear H is attached to the other end of the shaft gear G,
Further, the gear H meshes with a gear I attached to one end of the rotating shaft 19. At the other end of the rotating shaft 19, a target rotation disk 9 arranged below the target revolution disk 8 is attached. Therefore, the rotational force of the target rotation motor 13 is transmitted in the order of gear C → gear D → gear E → gear F → shaft gear G → gear H → gear I → target rotation disk 9 and is set on the target rotation disk 9. The target on the rotating disk is rotated (rotated).

Once the target rotation motor 13 is turned on, the target rotation motor 13 continues to rotate continuously until the switch is turned off again, and its rotation speed can be continuously adjusted between 0 and 10 rpm. .

In order to stack the intermediate layer and the superconducting thin film on the base material using the above-described apparatus, the inside of the vapor deposition chamber 2 is depressurized by operating the vacuum pump 5. Next, the base material 7 is sent out from a sending device (not shown) and supplied onto the base 6 at a predetermined speed, and the laser beam generated by the laser oscillation device 4 is irradiated on the target 10 a in the evaporation processing chamber 2. . Prior to the laser beam irradiation, the target revolution motor 12 is operated to rotate the target revolution disk 8 by a predetermined angle, and the target 1 is moved to the laser beam irradiation position.
0a is located. By performing the above operation, the intermediate layer 7 is generated from the target 10a and the intermediate layer 7 is sequentially formed on the moving substrate 7 as shown in FIG.
a can be formed. The substrate 7 on which the intermediate layer 7a is formed is sequentially sent to the winding device side and wound. ＄ Also, while rotating the target 10 by the rotational force transmitted from the target rotation motor 13, the laser beam is irradiated onto the target 10 a for a predetermined time, and transmitted from the target revolution motor 12 every time the irradiation for the predetermined time is completed. The target revolving disk 8 is rotated by the applied rotational force, and a new disk-shaped target 1 is placed in the laser beam irradiation area.
Since the target setting mechanism 3 for feeding the laser beam 0a is provided, the laser beam is not intensively irradiated to one location on the disk-shaped target 10a, but is uniformly applied to a certain range on the surface of the disk-shaped target 10a. Therefore, the energy density of the laser beam irradiated on the disc-shaped target 10a becomes almost constant even immediately after the start of the laser beam irradiation or after a certain period of time after the irradiation, and the laser beam is emitted during the laser beam irradiation. Target particle amount and substrate 7
The film quality and thickness of the film deposited on the film are always constant during the film forming operation.

Thus, using the laser vapor deposition apparatus 1 of this embodiment, for example, to manufacture a long superconductor,
Even if the laser vapor deposition operation is performed for a long time of up to 30 hours, the intermediate layer 7a having a uniform composition and a uniform film thickness can be formed on the substrate 7.

When the film forming operation is continued for a predetermined time while exchanging the target 10a, and the intermediate layer 7a having a predetermined thickness is formed on the long base material 7, next, the feeding device is moved from the winding device side. The base material 7 is moved in the reverse direction, the target revolving disk 8 is rotated again, and the target 10b is moved to the laser beam irradiation position, and the target 10b is irradiated with the laser beam to generate particles for forming a superconducting thin film. Thus, a superconducting layer 7b shown in FIG. 5 is formed on the intermediate layer 7a on the base material 7. Also, the heater built in the base 6 allows
If necessary, heat treatment is applied to superconducting thin film 7b to homogenize the film quality.

During the formation of the superconducting thin film 7b, the target revolving disk 8 is revolved at a predetermined angle at predetermined time intervals to sequentially exchange a plurality of targets 10b, thereby forming the superconducting thin film 7b on a long base material sequentially. I do. Here, for example, even if a long-time laser deposition operation for as long as 20 to 30 hours is performed to produce a long superconductor, a uniform film having a uniform composition is formed on the intermediate layer 7a of the base material 7. A thick superconducting thin film 7b can be formed.

(Experimental Example) Using the laser vapor deposition apparatus 1 having the above-described structure, a superconductor was actually manufactured using a target revolving disk 8 on which a target 10a and a target 10b were installed as shown in FIG. Target 10a is a disk-shaped target of YSZ, the target 10b Y _1.0 Ba _2.0
This is a disk-shaped target having a composition of Cu _3.0 O _7-x . First, a Hastelloy alloy base material 7 having a length of 1 m, a width of 5 mm, and a thickness of 0.1 mm is supplied onto the base 6 at a speed of 8 cm / min from a delivery device, and passed through the base 6. Was wound up by a winding device. Further, the inside of the vapor deposition processing chamber 2 is evacuated to 2.0 × 10 ⁻¹ Torr by the vacuum exhaust pump 5, and a heater built in the base 6 is turned on to evacuate the substrate 7 to 700 to 10 ⁻¹ Torr. Heated to 730 ° C.

At the same time, the main switch of the target revolving motor 12 and the switch of the target revolving motor 13 are turned on, the target revolving disk 8 is rotated by 36 degrees every 24 minutes, and the targets 10a are sequentially exchanged. It was set to rotate at a speed of 3 rpm. The laser deposition operation under the above conditions was performed continuously for 2 hours to form an intermediate layer on the substrate. Next, in the same processing time, while the substrate is reversely moved from the winding device to the sending device side,
The target 10b was moved at the same revolution time and rotation speed as described above, and a superconducting layer was formed sequentially on the intermediate layer.

By the above operation, a superconductor in which an intermediate layer of YSZ and a YBaCuO-based superconducting thin film were laminated on the substrate 7 was produced. In the obtained superconductor, the thickness of the intermediate layer was 0.4 to 0.5 μm, and the thickness of the superconducting thin film was about 1 μm.
When the composition of the superconducting thin film was examined by fluorescent X-ray analysis, the composition was uniform. The long superconductor has a critical temperature of 88 to 90K and a critical current density of 1.0 × 10 ⁴ A / cm ² (77
K, 0T).

FIG. 6 shows another example of a superconductor manufactured by applying the method of the present invention. The superconductor in this example is
It has a structure in which two intermediate layers 7a and two superconducting thin films 7b are alternately laminated on a base material 7. In order to manufacture the superconductor having the structure shown in FIG. 6, the substrate 7 is reciprocated a plurality of times on the base 6 using the manufacturing apparatus shown in FIGS. The intermediate layers 7a and the superconducting thin films 7b are alternately stacked by using them alternately. By performing this operation, a superconductor having a multilayer structure shown in FIG. 6 can be manufactured. By repeating the above operation three or more times, a superconductor having a multilayer structure of three or more layers can be manufactured.

[0034]

As described above, according to the present invention, a laser beam is radiated to a predetermined area on the target for a predetermined time, and each time the irradiation for a predetermined time is completed, the target is rotated by the installed disk rotating means. By rotating the installation disk, a new disk-shaped target can be sent to the laser beam irradiation area, so that the laser beam does not irradiate one location on the target, and a certain area on the target surface Can be irradiated on average.

For this reason, the energy density of the laser beam irradiated on the target becomes almost constant even immediately after the start of laser beam irradiation or after a certain period of time after irradiation, and the laser beam is emitted during laser beam irradiation. The amount of target particles and the quality and thickness of the film deposited on the substrate are always constant during the film forming operation. Therefore, in order to produce a long superconductor, when performing a laser deposition operation for a long time, even with long-term laser beam irradiation, with a uniform composition on the substrate,
In addition, there is an effect that an intermediate layer and a superconducting thin film having a uniform thickness can be formed.

[Brief description of the drawings]

FIG. 1 is a schematic view showing one embodiment of a laser vapor deposition apparatus of the present invention.

FIG. 2 is a diagram showing details of a target setting mechanism shown in FIG. 1;

FIG. 3 is a plan view showing a first example of target installation.

FIG. 4 is a plan view showing a second example of target installation.

FIG. 5 is a sectional view of a superconductor obtained by carrying out the method of the present invention.

FIG. 6 is a cross-sectional view showing another structural example of a superconductor obtained by performing the method of the present invention.

[Explanation of symbols]

Reference numeral 1 denotes a laser vapor deposition apparatus, 3 denotes a target setting mechanism, and 4
... Laser oscillation device, 6 ... Base, 7 ... Substrate, 8 ... Target revolving disk, 9 ... Target rotating disk, 10a, 10
b: target, 12: target revolving motor, 13:
Target rotation motor,

────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Satoru Kono 1-5-1 Kiba, Koto-ku, Tokyo Fujikura Electric Wire Co., Ltd. (56) References Real Open 50-145751 (JP, U) (58) Survey Field (Int.Cl. ⁷ , DB name) C23C 14/28 ZAA

Claims (1)

(57) [Claims] A chamber for accommodating a target, a base material, and a base; a laser beam oscillator for irradiating the target with a laser beam; and a laser beam emitted from the oscillator for irradiating the target surface. A target setting means for setting the target at a position, wherein the target setting means has a disk shape, and a plurality of disk targets are arranged on one surface thereof along a circumferential direction thereof. Using a laser deposition apparatus consisting of a disk and a rotating means for rotating the target installation disk, a long base material is continuously supplied to the base, and an intermediate layer and a superconducting thin film are laminated on the base material. A method for manufacturing a superconductor, comprising: a plurality of first targets for forming an intermediate layer and a plurality of second targets for forming a superconducting thin film, on the target installation disk. First, one of the first targets is irradiated with a laser beam for a predetermined time, and thereafter, the installation disk is rotated to irradiate the other first target with a laser to form an intermediate layer a required number of times. After forming the intermediate layer on the material, the installation disk is rotated to irradiate one of the second targets with a laser beam for a predetermined time, and then the installation disk is rotated and the other second target is irradiated with the laser beam. A superconducting thin film formed on an intermediate layer by performing a plurality of times of the above processes.