JPH0548164A - Manufacture of superconducting wiring - Google Patents

Abstract

PURPOSE:To easily manufacture a superconducting wiring having high performance. CONSTITUTION:A part to be formed with an interwiring insulating layer 20 of an MgO substrate 3 heated to 700-750 deg.C is irradiated with a CO2 laser beam 15, a temperature of the part is set to 770-850 deg.C, and a Y1Ba2Cu3O7-xoxide superconducting thin film is formed by a sputtering method. An amorphous nonsuperconducting thin film is grown on a part having high substrate temperature, and a Y1Ba2Cu3O7-x oxide superconducting thin film of c-axis orientation is grown on the other part to become a superconducting wiring.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing superconducting wiring. More specifically, the present invention relates to a method for producing a superconducting wiring used in a superconducting integrated circuit or the like with an oxide superconductor.

[0002]

2. Description of the Related Art With the progress of researches on the application of oxide superconductors, the feasibility of various superconducting devices and superconducting elements has increased. It is considered that an element utilizing the superconducting phenomenon is faster than a conventional semiconductor element, consumes less power, and can dramatically improve the performance of the element.

On the other hand, making not only the elements but also the wiring between the elements superconducting also contributes to the high performance of the device. That is, by using a superconductor for the wiring between the elements, the signal propagation speed can be improved and the power consumption can be reduced. Furthermore, since heat is not generated in the wiring part, especially when combined with a superconducting element,
It becomes easy to operate the superconducting element stably.

[0004]

However, as a method of producing a superconducting wiring using an oxide superconductor, a method of processing an oxide superconducting thin film using a photolithography technique has been proposed. However, since the oxide superconductor is a material having a relatively high reactivity, it may be deteriorated by reacting with a resist, a developer, a stripping agent, an etching solution, an etching gas, etc. used in a processing step by photolithography. .. Therefore, it has been difficult to manufacture a superconducting wire having excellent characteristics by using the conventional method using the oxide superconductor.

Therefore, an object of the present invention is to solve the above-mentioned problems of the prior art and to provide a method for producing a superconducting wiring having excellent characteristics by an oxide superconductor.

[0006]

According to the present invention, in a method for producing a superconducting wire made of an oxide superconductor on a substrate, the temperature of a portion of the substrate where the superconducting wire is formed is controlled by the oxide superconducting material. A temperature suitable for forming a thin film of the body, and the temperature of the portion of the substrate where the inter-wiring insulating layer is formed is 50 ° C. or more higher than the temperature suitable for forming the thin film of the oxide superconductor. Thus, there is provided a method for producing superconducting wiring, which comprises depositing a thin film of an oxide superconductor on the substrate.

[0007]

According to the method of the present invention, when a superconducting wiring made of an oxide superconductor is formed on a substrate, a temperature distribution is given to the substrate to form an oxide superconducting thin film, and the superconducting wiring and the inter-wiring insulating layer are formed. Form at the same time. That is, in the method of the present invention, the temperature of the portion of the substrate where the superconducting wiring is formed is set to a temperature suitable for forming the oxide superconducting thin film, and the temperature of the portion of the substrate where the inter-wiring insulating layer is formed is set to the oxide superconducting layer. The temperature should be 50 ° C higher than the temperature suitable for thin film formation. When an oxide superconducting thin film is formed on a substrate having such a temperature distribution,
A good oxide superconducting thin film grows in the part where the substrate temperature is appropriate, but in the part where the substrate temperature is high, the composition of the oxide superconducting thin film differs from that of the oxide superconducting thin film in the superconducting wiring part due to decomposition of the oxide superconductor during film formation. The critical temperature of the thin film grown in this portion is greatly lowered or it does not exhibit superconductivity, and becomes a substantially non-superconducting thin film. Therefore, according to the method of the present invention, the superconducting wiring made of an oxide superconductor and the inter-wiring insulating layer can be simultaneously formed.

In the method of the present invention, as described above, when an oxide superconducting thin film is to be formed on a substrate having a substrate temperature higher than an appropriate temperature, the oxide superconductor is decomposed during the film formation and loses its superconductivity. I'm taking advantage of that. Therefore, in the method of the present invention, the temperature of the portion of the substrate where the inter-wiring insulating layer is formed must be equal to or higher than the temperature at which the oxide superconductor decomposes and loses its superconductivity. This temperature is generally higher than the appropriate film forming temperature of the oxide superconducting thin film by 50 ° C. or more, and for example, in the case of Y ₁ Ba ₂ Cu ₃ O _7-X oxide superconducting thin film, the appropriate film forming temperature. A temperature of 70 ° C. or higher is particularly preferable.

In the method of the present invention, it is not necessary to maintain the temperature distribution of the substrate until the end of film formation. This is because when the thin film grows to a thickness of about 5 nm, the thin film grown on it grows reflecting the crystal structure of the lower layer even if the substrate temperature is constant. Therefore, according to the method of the present invention, if the temperature distribution of the substrate is continuously given from the start of film formation until the thin film grows to a thickness of about 5 nm, even if the substrate temperature is kept constant thereafter, the oxide superconductivity at that time is maintained. An oxide superconducting thin film grows on the part where the thin film grows, and a non-superconducting thin film grows on the part where the non-superconducting thin film grows. Therefore, it is not always necessary to maintain the temperature distribution of the substrate until the end of film formation.

In the method of the present invention, it is preferable to use a light beam to provide the above temperature distribution to the substrate. As described above, in the method of the present invention, the temperature distribution may be given to the substrate only at the initial stage of film formation. Therefore, the method of locally heating the substrate by irradiating the substrate with a light beam from above is used. It is possible. In particular, heating with a light beam is preferable because a fine inter-wiring insulating layer can be easily formed by narrowing and scanning the light beam. Any light beam can be used as long as it can provide the above-mentioned temperature distribution to the substrate. For example, a CO ₂ laser has a wavelength in the infrared region, which is advantageous.

The present invention can be applied to any oxide superconductor, but the Y ₁ Ba ₂ Cu ₃ O _{7 -X} oxide superconductor is preferred because it can stably obtain a high quality thin film with good crystallinity. .. Further, the Bi ₂ Sr ₂ Ca ₂ Cu ₃ O _x oxide superconductor is particularly preferable because its superconducting critical temperature Tc is high.

Hereinafter, the present invention will be described in more detail with reference to examples, but the following disclosure is merely examples of the present invention and does not limit the technical scope of the present invention.

[0013]

EXAMPLE Superconducting wiring was produced by the method of the present invention. FIG. 1 shows a conceptual diagram of an example of an apparatus for producing superconducting wiring by the method of the present invention. The apparatus shown in FIG. 1 is a sputtering apparatus capable of irradiating a substrate on which a thin film is being formed with a laser, and a target equipped with a target 2 that is arranged to face the bottom and the top of a chamber 1 respectively. Substrate holder 5 on which holder 4 and substrate 3 are mounted
It is equipped with. A high frequency power supply 6 is connected to the target holder 4, and a heater 7 is provided on the substrate holder 5.
Further, the chamber 1 is provided with a gas introduction hole 8 for introducing atmospheric gas from the outside, an exhaust hole 9 connected to an exhaust pump (not shown), and a light incident window 10. A CO ₂ laser 11, a mirror 12, a lens 13, and a mirror control device 14 are provided outside the chamber 1, and a laser beam 15 is placed at an arbitrary position on the substrate 3 fixed on the substrate holder 5.
Is configured to be capable of irradiation.

Referring to FIG. 2 together, a process of producing superconducting wiring by the method of the present invention using the apparatus of FIG. 1 will be described. FIG. 2 is a conceptual diagram in which the vicinity of the substrate 3 of FIG. 1 is enlarged. First, the target 2 and the substrate 3 are attached to the target holder 4 and the substrate holder 5 of the chamber 1, respectively. In this embodiment, the target 2 is an oxide having an atomic ratio of Y: Ba: Cu of 1: 2: 3, and the substrate 3 is
A MgO (100) substrate was used.

Next, the chamber 1 was evacuated to a high vacuum, Ar: O ₂ was introduced from the gas introduction hole 8 at a volume ratio of 9: 1, and the internal pressure was adjusted to 10 Pa. The MgO substrate 3 is heated to 70 by the heater 7.
It is heated to 0 to 750 ° C., and the portion 20 of the MgO substrate 3 where the inter-wiring insulating layer is formed is irradiated with the CO ₂ laser beam 5 while scanning to bring the temperature of the portion to 770 to 850 ° C. The output of the CO ₂ laser beam 5 was 10 W and was 10 μmφ, and scanning was performed at a speed of 2 m / min.

When the above-mentioned temperature distribution is given to the MgO substrate 3,
The high frequency power supply 6 is energized, and Y ₁ Ba ₂ Cu ₃ O _{7-X is formed} on the MgO substrate 3.
The film formation of the oxide superconducting thin film is started. In the part where the substrate temperature of the MgO substrate 3 is appropriate (700 to 750 ° C), Y ₁ B with c-axis orientation is formed.
An amorphous thin film grows in the portion 20 where the a ₂ Cu ₃ O _7-X oxide superconducting thin film grows and the inter-wiring insulating layer where the substrate temperature is raised by the CO ₂ laser beam is formed. When the thin film grows to a thickness of about 5 nm on the MgO substrate 3, the thin film that grows thereafter grows epitaxially. That is, thereafter, even if the temperature of the MgO substrate 3 is uniform, an amorphous thin film grows in the portion 20 where the inter-wiring insulating layer is formed,
A c-axis oriented Y ₁ Ba ₂ Cu ₃ O _7-X oxide superconducting thin film grows on the other part. Therefore, the irradiation of the CO ₂ laser beam may be stopped when the thin film grows to about 5 nm. afterwards,
The superconducting wiring is completed when the thin film is grown to about 200 nm.

In the superconducting wiring manufactured by the method of the present invention, the superconducting wiring portion was not deteriorated by the influence of the inter-wiring insulating layer, and the fine portion was processed accurately. The superconducting characteristics of the superconducting wiring part are shown below. Critical temperature Tc 85K Critical current density Jc 1.5 × 10 ⁵ A / cm ²

[0018]

As described above, according to the present invention,
A method for making a superconducting wire using an oxide superconductor is provided. By applying the present invention to the production of superconducting electronic equipment, it is possible to produce a high-performance electronic device which has never been obtained.

[Brief description of drawings]

1 is a schematic view of an example of an apparatus for carrying out the method of the present invention.

FIG. 2 is a conceptual diagram when the method of the present invention is implemented.

[Explanation of symbols]

1 Chamber 2 Target 3 Substrate 4 Target Holder 5 Substrate Holder 11 CO ₂ Laser Device

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display location // H01B 12/06 ZAA 8936-5G

Claims (1)

[Claims] 1. A method for producing a superconducting wire made of an oxide superconductor on a substrate, wherein the temperature of a portion of the substrate where the superconducting wire is formed is suitable for forming a thin film of the oxide superconductor. And a temperature of a portion of the substrate where the inter-wiring insulating layer is formed is higher than a temperature suitable for forming a thin film of the oxide superconductor by 50 ° C. or more,
A method for producing a superconducting wiring, comprising forming a thin film of an oxide superconductor on the substrate.