JPH01107582A - Forming method of superconductor circuit and superconductor element - Google Patents

Abstract

PURPOSE:To form an arbitrary superconductor circuit, by forming an insulator and a switching circuit on a superconductor thin film by using focused beam. CONSTITUTION:Impurity ions are implanted into a desired place in a superconductive layer 1 by using a focused ion beam 4. Thus an ion implanted layer 5 is formed. In the ion implanted layer 5, a superconductive state is broken, and an insulator is formed. Meanwhile, when the ion beam, which is emitted from a liquid metal ion source or an electric-field ionizing ion source, is used, the beam can be focused into a micron order or less. Thus, the ions can be implanted accurately both for a position and a depth. Therefore, the insulator can be formed in an arbitrary region on the superconductive thin film layer. Wirings, which are crossed in three dimensions through the insulating film with respect to superconductive wirings, are formed by using local films formed with the focused beam. Power sources, which supply currents to the locally formed film wirings, are provided. Thus, a switching circuit is formed. In this way, an arbitrary superconductor circuit can be formed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a superconducting element, and particularly to a method for forming a superconducting circuit using a focused beam, which is suitable for forming any circuit.

[Conventional technology]

Currently, intense competition is underway around the world to develop ceramics, particularly Y-Ba-Cu-0-based high-temperature superconductors. Among these, it has recently been reported that when impurities are implanted into ceramic high-temperature superconductors, the resistance increases rapidly. For example, P47 rY-B of Nikkei Microdevices September 198 issue.
A-Cu-F-〇 system superconductivity is real, China succeeds in follow-up test.”
In the article, Y-Ba-C was originally used for the purpose of lowering the critical temperature.
In an experiment in which F was implanted into a u-0 superconductor, it was reported that simply implanting F would cause a sudden increase in resistance.

[Problem that the invention seeks to solve]

In the above reported example, it is reported that when F ions are implanted as an impurity into the entire superconductor, the resistance increases rapidly.

On the other hand, if a focused ion beam is used, impurities can be selectively implanted into any minute region in a sample with high precision.

Therefore, by selectively implanting impurities into a superconducting thin film layer formed on a substrate using a focused ion beam to form an insulator, it is possible to directly draw superconducting wiring and cutting superconducting circuits.

Furthermore, if a switching circuit of superconducting wiring can be formed using a focused beam, it becomes possible to form any circuit on a superconducting thin film layer.

An object of the present invention is to provide a method for forming a superconducting circuit and a superconducting element, which make it possible to form an arbitrary superconducting circuit by forming an insulator and a switching circuit on a superconducting thin film using a focused beam.

[Means for solving problems]

Formation of an insulator on a superconducting thin film is achieved by selectively implanting impurities using a focused ion beam.

In addition, to form a switching circuit, local film formation using a focused beam such as a focused ion beam is used to form wiring that three-dimensionally intersects the superconducting wiring via an insulating film, and supplies current to the already locally formed wiring. This is achieved by providing a power source for

[Effect]

Inside the ceramic superconductor, the constituent atoms are regularly arranged to form a crystal structure. When high-energy ions are implanted into this crystal, the crystal structure is destroyed and impurity levels are created, blocking the flow of superconducting current and causing a sudden increase in resistance. Therefore, by selectively implanting impurity ions into the superconducting thin film using a focused ion beam,
An insulator can be formed at the implant location.

In addition, superconductors have three critical conditions: critical temperature T
There is a critical current density J, c, a critical magnetic field He, and - if any of the conditions exceeds the critical value, the superconducting state will be destroyed.Therefore, local film formation using a focused beam such as a focused ion beam is used to By forming a wiring that three-dimensionally intersects the superconducting wiring via an insulating film and supplying sufficient current to the locally formed wiring, the magnetic field generated by the current can be reduced to He
It can be made sufficiently larger and can cut off superconducting current. This allows switching in superconducting circuits.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings.

<Embodiment 1> FIG. 1 shows the principle of this embodiment. A superconducting layer 1 is formed on a substrate 3 with an insulating layer 2 interposed therebetween. Impurity ions are implanted into desired locations of the superconducting layer 1 using a focused ion beam 4 to form an ion implantation layer 5. The ion implantation layer 5 destroys the superconducting state and forms an insulator. On the other hand, if an ion beam emitted from a liquid metal ion source or a field ion source is used, the beam can be focused on the order of micrometers or less, and the ions can be implanted with high precision in both position and depth. An insulator can be formed in the region.

FIG. 2 shows an example of forming superconducting wiring according to this embodiment. An ion implantation layer 5gt5b is formed using a focused ion beam around a region where a superconducting wiring is to be formed, and the superconducting wiring 6 is formed by separating and insulating it from the surrounding superconducting layers. Using this method, superconducting wiring can be directly drawn using a focused ion beam.

FIG. 3 shows an example of forming a Josephson junction according to this embodiment. -r on implantation layer 5c using a focused ion beam
, 5d are formed, and a Josephson junction 7 is formed by a minute bridge portion narrowed between both implanted layers. Here, when a focused ion beam is used for implantation, the acceleration energy is 100 keys or more, but if the acceleration energy is lowered to several tens of keys and the beam current is increased, the effect of physical sputtering becomes noticeable. FIG. 4 shows an example in which a Josephson junction similar to that shown in FIG. 3 was formed by processing a desired region of the superconducting layer using sputtering.

<Example 2> FIG. 5 shows a method of forming a superconducting switching circuit of this example. By irradiating a sample with a focused beam such as a focused ion beam or a focused laser beam in a CVD gas atmosphere, it is possible to locally form a film in the area irradiated with the focused beam. For example, an example in which a Si insulating film is formed using an A r F laser beam as a focused beam and a mixed gas of SiH4 and N20 as a CVD gas, or an example in which an aa ion beam is used as a focused beam and W (CO) as a CVD gas is formed. Many examples of local film formation have been reported, including examples in which W wiring was formed using the same method. Therefore, by using local film formation using a focused beam, we first deposited a CVD insulating film 1 on the superconducting wiring 9.
form 0. Furthermore, it passes over the CVD insulating film 10 and intersects the superconducting wiring in three dimensions.

CVD wiring 12 is formed. Both ends of the CVD wiring 12 are connected to pads lla and llb to supply current.

FIG. 6 shows the operating principle of the switching circuit formed as described above. Here, superconductors have three critical conditions: critical temperature Tc, critical current density Jc, and critical magnetic field Ha.
If any of the conditions exceeds the critical level, the superconducting state will be destroyed. Therefore, by applying a magnetic field sufficiently larger than Hc to the superconducting wiring from the outside, the superconducting current can be interrupted. In the left diagram of FIG. 6, the CVD wiring 12
No current is flowing through the superconducting wire 9, and a superconducting current flows within the superconducting wire 9. On the other hand, in the right diagram of FIG. 6, the superconducting current is cut off by a magnetic field (dotted line arrow in the diagram) generated when a sufficient current is passed through the CVD wiring 12. As above, CVD
By turning off the current to the wiring 12, the superconducting current can be switched.

<Example 3> FIG. 7 shows a superconducting element of this example and a method for forming its circuit. The superconducting element includes superconducting electrodes 13 and superconducting wiring 14 connecting them in a grid pattern.

It consists of electrodes 15 provided between each grid. Using Example 1, insulating parts 16a to 16d are provided on desired superconducting wiring and the wiring is cut, and using Example 2, switching circuits 179 to 17d are provided on desired superconducting wiring. In the manner described above, any circuit that exhibits the desired operation as a whole can be formed.

〔Effect of the invention〕

As explained above, according to the present invention, an insulator and a switching circuit can be formed on a superconducting thin film using a focused beam, so that an arbitrary superconducting circuit can be formed.

[Brief explanation of the drawing]

FIG. 1 is a diagram explaining the principle of Example 1, FIG. 2 is a schematic diagram showing an example of superconducting wiring formation, FIGS. 3 and 4 are schematic diagrams showing an example of Josephson junction formation, and FIG. 5 is a schematic diagram showing an example of forming a Josephson junction. FIG. 6 is a schematic diagram showing the operating principle of the switching circuit. FIG. 7 is a schematic diagram showing the superelectric element of Example 3 and the method for forming the circuit. DESCRIPTION OF SYMBOLS 1... Superconducting layer, 2... Insulating layer, 3... Substrate, 4
... Focused ion beam, 5... Ion implantation layer,
6...Superconducting wiring, 7...Josephson junction, 9.
...Superconducting wiring, 10...CVD insulation film, 12...
CVD wiring. Representative Patent Attorney Katsuo Ogawa (\,・″・J″゛, line 11i4' 躬2圀躬1 line 4 solid 7...ji: If!7・ruimo [@-1goiN) Isotsu
Te＼CN

Claims (1)

[Claims] 1. A superconducting layer is characterized by insulating circuit elements by processing with a focused beam or implanting impurities, and forming a switching circuit by using local film formation by a focused beam. A method for forming superconducting circuits. 2. Claim 1, characterized in that the circuit elements are insulated by physically removing a part of the superconducting layer using sputter processing using a focused ion beam or thermal processing using a focused laser beam. The method for forming a superconducting circuit described in . 3. The superconductor according to claim 1, wherein impurities are selectively implanted into desired regions of the superconducting layer using a focused ion beam to form an insulator and insulate circuit elements. How to form a circuit. 4. Using local film formation using focused ion beams, focused electron beams, focused laser beams, etc., we formed wiring that three-dimensionally intersects the superconducting wiring through an insulating film, and passed current through the already locally formed wiring. 2. The method for forming a superconducting circuit according to claim 1, wherein a switching circuit is formed in which a superconducting wiring is switched using a magnetic field generated when the superconducting circuit is formed. 5. Consisting of superconducting wiring formed in a lattice shape and electrodes provided between the lattices, the superconducting wiring is cut at a desired location, and the existing interstitial electrodes are connected to create a three-dimensional intersection with the superconducting wiring via an insulating film. 1. A superconducting element characterized in that an arbitrary circuit can be formed by forming wiring and forming a switching circuit at a desired location.