JPH02156073A - Production of thin superconductor film - Google Patents

Abstract

PURPOSE:To obtain a high quality thin film at a low temp. by decomposing clusters of superconductor ceramics generated from a generating source and transferred toward a body for deposition by irradiation with laser beam. CONSTITUTION:A target 31 is irradiated with laser beam 32 for generating clusters to generate clustery sputtered particles 34a of superconductor ceramics from the target 31 and the transfer the particles 34a toward a body 35 for deposition. The clustery sputtered particles 34a are then irradiated with other laser beam 33 for decomposing clusters to decompose the clusters during transfer and the resulting atomic sputtered particles are deposited on the substrate 35 to form a thin film of the superconductor ceramics. The clusters may be generated by any method.

Description

[Detailed Description of the Invention] <Prior Art> RF sputtering and laser beam sputtering are known as techniques for producing thin films by sputtering.

<Problem to be solved by the invention> In RF sputtering, sputtered particles have large energy, so re-spatter on the adherend (substrate) occurs to a considerable extent, which causes spatter to be formed on the adherend. There was a problem that the composition of the thin film was not constant. There was also the problem that the growth rate of the thin film could not be made very fast.

In laser beam sputtering, on the other hand, as shown in FIG. However, since the kinetic energy per atom constituting the cluster particles 23 is smaller than that of normal sputtered particles, the cluster particles 23 can be sputtered on the adherend without causing re-sputtering on the adherend (substrate 24). The macroscopic composition of the thin film 25 formed on the target 21 can be easily brought close to the composition of the target 21.

Furthermore, since the thin film 25 is formed by supplying the clusters 23 to the adherend 24, the thin film growth rate can be significantly increased compared to the RF sputtering method described above.

However, since the sputtered particles 23 are cluster-like, the microscopic composition of the thin film 25 formed on the adherend 24 may become non-uniform or the tightness of the formed thin film 25 may be impaired. The temperature Tc decreases and the critical current density Jc
This causes a problem in that the epitaxial growth of the thin film 25 itself is inhibited. Also,
Since the surface roughness of the formed thin film 25 becomes large, the resist film during pattern formation has to be thick when fabricating devices, and this results in low resolution and makes microfabrication impossible. There was a problem that it would disappear. To avoid such problems, heat treatment at a considerably high temperature is required to promote the diffusion of clusters on the substrate 24, which has caused a major obstacle in the production of superconductor thin films under low-temperature conditions.

The present invention was made in view of the above-mentioned conventional circumstances, and an object of the present invention is to provide a method capable of forming a high-quality superconductor thin film under low temperature conditions.

<Means for Solving the Problems> The first invention of the present application to solve the above problems is to generate clusters of superconducting ceramics from a cluster generation source, move them to the adherend side, and decompose the clusters during the movement. A method for producing a superconductor thin film, characterized in that a superconductor ceramic thin film is formed on the adherend.

Further, a second invention of the present application to solve the above problem is to irradiate a target of superconducting ceramics with a laser beam to generate clusters of superconducting ceramics, and irradiate the clusters with another laser beam different from the laser beam. This method of manufacturing a superconductor thin film is characterized in that a thin film of superconductor ceramics is formed on the adherend by decomposing the cluster during movement.

<Operation> In the first invention of the present application, the superconducting ceramic clusters generated from the cluster generation source are irradiated with, for example, excimer laser light to excite them, and the clusters are decomposed on the way to the adherend, Atoms obtained by decomposing the clusters are supplied onto an adherend to form a homogeneous thin film of superconducting ceramics under low temperature conditions.

In other words, the initial state is a cluster in which the kinetic energy per atomic unit is smaller than that of sputtered particles in conventional sputtering methods, and energy is applied to this cluster with laser light until it reaches the adherend. Decomposes to form a uniform thin film on the adherend. Incidentally, it is preferable that the addition of energy to the cluster by this laser beam ionizes the cluster to have a valence of two or more, so that the decomposition is further promoted by the repulsion of charges.

In the second invention of the present application, a cluster decomposition laser and other laser beams having different wavelengths and energies (for example, YAG laser) are used for the target of superconducting ceramics.
is irradiated to generate clusters with a composition very similar to that of the target, and these clusters are decomposed by laser beam irradiation on the way to the adherend in the same manner as above, and are placed on the adherend under low temperature conditions. form a uniform thin film at the bottom. That is, as shown in FIG. 1, two types of laser beams are used to generate sputtered particles 34 from a target 31 to form a superconductor thin film 36 on a substrate 35. First, as shown in FIG. As shown in FIG. 2(b), there is a process in which cluster-shaped sputtered particles 34a are generated from the target 31 by irradiating the target with a laser beam 32 for cluster generation, and a process in which cluster-shaped sputtered particles 34a are generated by a laser beam 33 for cluster decomposition as shown in FIG. 2(b). The method includes a process in which cluster-shaped sputter particles 34a are irradiated and decomposed, and atomic sputter particles are deposited on a substrate 35.

Incidentally, in the above-described first invention of the present application, there is no particular limitation on the method of generating clusters, and in addition to the above-mentioned laser beam irradiation, various methods such as forming clusters by turning raw material elements into plasma with a high-frequency electric field can be used. It can be used.

In addition, the laser beam for cluster decomposition can be irradiated onto the clusters between the target and the adherend.
It is preferable to irradiate the laser beam near the target because the generated clusters can be efficiently irradiated with the laser beam before the clusters spread.

<Example> First, as shown in FIG. 3, in an apparatus for carrying out the manufacturing method of the present invention, a target 4, a substrate 5, and a heating material are placed in a container 3 to which an oxygen supply pipe 1 and an exhaust pipe 2 are connected. Equipped with a heater 6,
It is equipped with a laser oscillator 9.10 facing a glass window 7.8 provided in the container 3.

Oxygen gas is supplied into the container 3 from an oxygen supply source (not shown) through an oxygen supply pipe 1, while the inside of the container 3 is exhausted through an exhaust pipe 2 connected to an exhaust device (not shown). . Further, the target 4 is supported by a holder having a rotation mechanism,
It rotates at a constant speed. Further, a substrate 5 facing the target 4 is heated by a heater 6. Further, the laser oscillators 9 and 10 are configured to irradiate laser beams to positions eccentric from the rotation center of the target 4, respectively.

Next, the results of manufacturing a superconductor thin film using the above-mentioned apparatus will be explained below.

First, the distance between the substrate 5 and the target 4 is 40 mm, and the composition of the target 4 is Bi: Sr: Ca: Cu: 0=
2: 2: 2: 3: X, the substrate 5 is made of MgO single crystal, and the Nd YAG laser beam (
Wavelength 1.064μm, pulse width 15ns, output 0°8
J/am2) to the target 4 to lower the internal pressure 3 of the container 3.
A thin film was formed on the substrate 5 at OX 10-'Torr and a substrate temperature of 600°C. The resulting thin film was 77
It did not exhibit superconductivity in the range up to K.

Next, under the above conditions, ArF is emitted from the laser oscillator 10.
Excimer laser light (wavelength 0.193 μm, pulse width I
ons, output I x 10-3 J/am2) was further irradiated onto the target 4. As a result, the deposition rate was 0.06 people/
B i-S at a critical temperature TC=87 on the substrate 5 with a pulse.
An r-Ca-Cu-0 based superconductor thin film was obtained.

Furthermore, when 45 CCM of oxygen gas was introduced near the substrate δ to increase the oxygen composition ratio, the critical temperature Tc=9
A B1-5r-Ca-Cu-0 based superconductor thin film was obtained.

<Effects> As explained above, according to the invention of the present application, cluster-like particles with relatively small kinetic energy per atom are decomposed into atoms by a laser beam during movement and deposited on an adherend. As a result, a dense and homogeneous superconductor thin film can be efficiently formed under low temperature conditions without causing re-spatter on the adherend. In addition, cluster-shaped sputtered particles are generated from the target using a laser beam for cluster generation, and these are decomposed by a laser beam for cluster decomposition and deposited on the adherend, so in addition to the above effects, the composition of the target Superconductor thin films with similar compositions can be easily obtained.

Furthermore, the excited state of the cluster can be easily controlled by the type of laser light, and fine control can be achieved depending on the superconductor composition, etc.

[Brief explanation of the drawing]

FIG. 1 is a conceptual diagram of a method for manufacturing a superconducting thin film according to an embodiment of the present invention, FIGS. 2(a) and (b) are conceptual diagrams of the manufacturing process of a superconducting thin film, and FIG. 3 is a conceptual diagram of the manufacturing process of a superconducting thin film according to an embodiment of the present invention. FIG. 4 is a conceptual diagram of a conventional superconductor thin film manufacturing method. 4. 21 and 31 are targets, 5. 24. 9. 35 is an adherend (substrate); 10 is a laser oscillator, 22. 32. 33 is a laser beam.

Claims (2)

[Claims] (1) Clusters of superconducting ceramics are generated from a cluster generation source, moved to the adherend, and irradiated with laser light to decompose the clusters during movement to form a thin film of superconducting ceramics on the adherend. A method for producing a superconductor thin film, characterized by: (2) A superconducting ceramic target is irradiated with a laser beam to generate a superconducting ceramic cluster, and the cluster is irradiated with another laser beam different from the laser beam to decompose the cluster while it is moving. A method for producing a superconductor thin film, comprising forming a superconductor ceramic thin film on an adherend.