JPH10188754A - Superconducting relay - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a superconducting relay which is not deteriorated by a magnetic field and whose resistance is zero when it is on and at infinite when it is off. SOLUTION: A pair of superconductor leads each having a thin superconductor film 2 are arranged so that at normal operating temperature their thin superconductor films 2 make electric contact with each other, with at least one of the superconductor leads comprising a bimetal lead 4 laminated with the thin superconductor film 2 and a layer 1 which is non-superconducting near the critical temperature of the thin superconductor film 2. Near the critical temperature of the thin superconductor film 2, the base layer 1 has a smaller coefficient of thermal expansion than the thin superconductor film 2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a superconducting relay, and more particularly to a superconducting relay having a bimetal lead structure in which switching is performed by Joule heat generated by a superconducting / normal conducting transition.

[0002]

2. Description of the Related Art Possibility of superconducting power transmission has been investigated with the recent increase in electric power transmission current, and since a signal waveform does not become dull with a resistance of 0, communication requiring high-speed signal transmission is required. Attempts to use superconducting wiring for transmission systems, interconnections between chips, and the like are also being studied.

In applications using these superconducting wires, a switch for turning on and off a superconducting current is required.
Many superconducting switches have been proposed to date. For example, superconducting / superconducting switches are generated by heat generated in a resistor arranged beside the superconducting wire or by a magnetic field generated by a coil arranged beside the superconducting wire. A switch that causes a transition to normal conduction, a reed switch that brings adjacent superconducting leads into contact with each other by a magnetic field, and so on has been proposed.

FIG. 9 is a sectional view of a main part of a conventional superconducting reed switch, in which a magnetic thin plate 71 made of an Fe--Ni alloy has N
The superconductive thin film 72 made of
The superconductor thin films 73 of the pair of superconducting leads 73 are arranged close to each other so as to face each other, and the close arrangement portion is sealed in a glass tube 74 together with He.

In this case, the magnetic thin plates 71 are brought close to each other by a magnetic field generated by applying a current to a coil (not shown) wound around the glass tube 74, thereby bringing the superconductor thin films 72 into contact with each other. When the coil current is stopped, the magnetic thin plate 7
The elastic member 1 returns to the original state and is brought into a non-contact state.

[0006]

However, in the case of the conventional superconducting reed switch, the magnetic thin plate 71 is used as the base layer constituting the superconducting lead 73.
There is a problem that the superconductivity of the superconductor thin film 72 is deteriorated by the magnetic field of the magnetic material.

Further, in this case, when a superconducting current flows in a normally-off state, an external magnetic field is applied by a coil. Therefore, there is a problem that the superconducting critical current is reduced by the external magnetic field.

[0008] In the case of a switch in which a superconducting / normal conducting transition is caused by heat generated in a resistor arranged beside the superconducting wire or by a magnetic field generated by a coil arranged beside the superconducting wire, The resistance in the off state is as small as several Ω,
There is a problem that an ideal switch such as a reed switch having an infinite resistance in an off state cannot be obtained.

Accordingly, it is an object of the present invention to provide a superconducting switch which is not deteriorated by a magnetic field, has a resistance of 0 in an on state, and has an infinite resistance in an off state.

[0010]

FIG. 1 is an explanatory diagram of the principle configuration of the present invention. Referring to FIG. 1, means for solving the problems of the present invention will be described. 1 (a) to 1 (c) (1) In the present invention, a pair of superconductor leads having a superconductor thin film 2 are electrically connected to each other in a normal state at an operating temperature. In a superconducting relay arranged to be in contact with at least one superconductor lead, a superconductor thin film 2 and a non-superconducting base layer 1 near a critical temperature of the superconductor thin film 2 are laminated. In addition to the bimetal lead 4, the thermal expansion coefficient of the base layer 1 is smaller than the thermal expansion coefficient of the superconductor thin film 2 near the critical temperature of the superconductor thin film 2.

As described above, the critical current of the superconducting current 5 flowing through the superconductor thin film 2 due to heat or a magnetic field applied from the outside is reduced from a to b as shown in FIG. Finally, when the bimetal lead 4 is used, physical contact of the bimetal lead 4 is made using the Joule heat generated in the superconductor thin film 2 due to the superconductivity / normal conduction transition. Can be canceled, so that the electric resistance in the off state can be made infinite.

In the ON state, no magnetic field is applied, so that there is no problem that the superconducting critical current is reduced by the magnetic field. Further, since it is not necessary to use a magnetic material as the base layer 1 constituting the bimetal lead 4. Also, the superconductivity of the superconductor thin film 2 does not deteriorate due to the magnetic field of the magnetic material. The contact portion may be provided with a contact conductor 3 made of a thin normal conductor. If the thickness of the contact conductor 3 is small, the superconducting current 5 flows due to the proximity effect.

(2) Further, the present invention is characterized in that, in the above (1), a resistor for generating heat is arranged near a contact portion where the superconductor thin films 2 are in electrical contact with each other. .

As described above, NiC for heat generation is provided near the contact portion.
The superconducting critical current flowing through the superconductor thin film 2 is reduced by the heat generated when a resistor such as r is placed and the current is passed through the resistor, and the superconducting critical current flows through the superconductor thin film 2. At the time when the current is lower than the current, the superconducting state is broken and transited to the normal conducting state, Joule heat is generated in the superconducting thin film 2, the bimetal is activated, and the physical contact is released to be turned off.

(3) The present invention is characterized in that, in the above (1), a coil for generating a magnetic field is arranged near a contact portion where the superconducting thin films 2 are in electrical contact with each other.

As described above, a coil such as a superconducting wiring layer is arranged near the contact portion, and a superconducting critical current flowing through the superconductor thin film 2 is reduced by a magnetic field generated by energizing the coil. When the superconducting critical current falls below the current flowing through the superconductor thin film 2, the superconducting state is broken and transitions to a normal conducting state, Joule heat is generated in the superconducting thin film 2, bimetal is activated, and The target contact is released and the device is turned off.

(4) Further, according to the present invention, in any one of the above (1) to (3), the pair of superconductor leads
It is characterized by being formed on the same supporting substrate.

As described above, by forming the superconducting relay using the bimetal lead 4 in an on-chip type,
A microminiature superconducting relay used in a microminiature superconducting circuit device can be configured.

(5) According to the present invention, in the above (4), the superconductor thin film 2 constituting one of the superconductor leads is provided on the same supporting substrate, and the bimetal lead 4 having the beam-like portion is provided. The superconductor thin films 2 are arranged to face each other via the spacer layer so as to be on the lower surface side, and the superconductor thin films 22 are in electrical contact with each other at least at the tip of the beam-shaped portion in a normal state at an operating temperature. It is characterized by the following.

As described above, by providing the bimetal lead 4 serving as the upper superconductor lead as a laminate with the spacer layer interposed therebetween, the superconductor thin film 2 constituting the bimetal lead 4 at an operating temperature such as liquid nitrogen temperature can be obtained. Base layer 1
Since it naturally contracts and curves downward and naturally contacts the superconductor thin film 2 constituting the lower superconductor lead, it is possible to form a normally-on superconducting relay by a simple film forming process and an etching process. it can.

(6) Further, according to the present invention, in any one of the above (1) to (5), the superconductor lead may have a strip line structure having a three-layer structure of superconductor / insulator / superconductor. It is characterized by having.

As described above, by adopting a superconductor / insulator / superconductor three-layer stripline structure as a superconductor lead, high-frequency characteristics can be improved and both sides can be improved. By changing the thickness or the material of the superconductor provided, the bimetal lead 4 can be obtained.

(7) The present invention is characterized in that in any one of the above (1) to (5), the superconductor lead has a coplanar strip line structure.

As described above, by adopting a coplanar type stripline structure as a superconductor lead,
The high-frequency characteristics can be improved, and the connection between the GND (ground) conductors constituting the strip line can be easily established wirelessly.

(8) The present invention is characterized in that in any one of the above (1) to (7), the superconductor thin film 2 constituting the superconductor lead is an oxide superconductor thin film. And

As described above, by using an oxide superconductor thin film as the superconductor thin film 2 constituting the superconductor lead, it is possible to operate a superconducting relay at a high temperature such as liquid nitrogen temperature. it can.

[0027]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Here, referring to FIG. 2, a glass-contained superconducting relay according to a first embodiment of the present invention will be described. Referring to FIG. 2A, first, a length of 2 cm, a width of 1 mm, and a thickness of 20 as a base layer are set.
A sintered zirconia sheet having a crystal structure stabilized by adding yttrium of μm, that is, a YSZ sheet (yttrium-stabilized zirconia sheet) 11, a length of 2 cm and a width of 1
mm, a high temperature superconductor of about 2 μm YBa ₂ Cu
After bonding the ₃ O _7-x (YBCO) sintered body thin plate 12 to the tip of the YBCO sintered body thin plate 12 by heating in an oxygen-containing atmosphere in a pressurized state, The bimetal lead 14 is formed by vapor-depositing the Au thin film 13 by a mask with a length of 5 mm.

Next, A of the pair of bimetal leads 14
In a state where the u thin films 13 are held apart from each other so as to face each other, a gas containing 1% or more of oxygen, for example, a He gas containing 20% of oxygen, and at least the tip portion provided with the Au thin film 13 are made of glass. After being sealed in the container 15, the periphery of the glass container 15 is wound around with a superconducting wire 16 to complete the superconducting relay.

In this case, the He gas is sealed in the glass container 15 in order to transmit the heat applied from the outside by the He gas, and oxygen is released from O atoms from the YBCO sintered compact thin plate 12. The content (partial pressure) is set so as not to liquefy at the liquid nitrogen temperature (77 K).

In this case, the separation distance of the tip of the bimetal lead 14 is set at the operating temperature, for example, 77K, and the YBCO sintered compact 12 having a large linear expansion coefficient (linear expansion coefficient: 1.4 × 10 ^−5). ℃) YSZ sintered body thin plate 11
(Linear expansion coefficient: 1.0 × 10 ^-5 ° C)
The distance at which the Au thin films 13 are physically in contact with each other.

By cooling the superconducting relay to an operating temperature of 77 K or the like, the bimetal leads 14 come into contact with each other due to a difference in linear expansion coefficient, so that the superconducting relay can flow a superconducting current.

In this state, a magnetic field generated by applying a current to the superconducting wire 16 is applied to the superconducting relay, and as the magnetic field becomes stronger, the YBCO sintered compact 1
The superconducting critical current flowing through the YBCO 2 becomes small, and when the magnetic field exceeds a certain level, the superconducting state is broken. Then, the generated heat causes the bimetal leads 14 to move in a direction away from each other, releasing the physical contact and turning off.

Therefore, in such a superconducting relay, the resistance can be set to 0 in the on state and to infinity in the off state, so that an ideal switch can be obtained.

In the on state, since no magnetic field is applied, the superconducting critical current is reduced by the magnetic field,
The current flowing through the YBCO sintered compact 12 is not restricted.

FIG. 2B shows a superconducting wire 16 in the superconducting relay shown in FIG.
Since the other configuration is exactly the same as that of FIG. 2A, the description of the manufacturing process is omitted, and the off operation will be described.

In this superconducting relay in the ON state, the heat generated by passing an electric current through the metal wire 17 is applied to the superconducting relay via the He gas sealed in the glass container 15, and the generated heat becomes stronger. According to YB
The superconducting critical current flowing through the CO sintered compact 12 is reduced, and when the heat exceeds a certain level of heat, that is, the current flowing through the metal wire 17, the superconducting state is broken, and the superconducting state changes to the normal conducting state, and the YBCO burning Normal conduction current flows through the united thin plate 12 to generate Joule heat, and the generated heat causes the bimetal leads 14 to move in a direction away from each other, releasing physical contact and turning off.

In this case, since a magnetic field is generated simultaneously with the heat, a magnetic field is applied to the superconducting relay simultaneously with the heat. However, the shape of the metal wire 17 and the structure of the metal wire 17 The influence of heat may be greater than the influence of a magnetic field by appropriately selecting a material to be used.

Further, in the case of the first embodiment shown in FIGS. 2A and 2B, the YSZ sintered body thin plate 11 which is an insulator is used as the base layer. It is not necessary to use Au or P which shows normal conductivity at the operating temperature.
It is also possible to use a metal such as t.
It is only necessary to use a non-superconductor having a smaller linear expansion coefficient near the operating temperature than the CO sintered body thin plate 12, that is, a smaller coefficient of thermal expansion.

A normal conductor Au thin film 13 is used as a contact conductor, and since the thickness is as thin as 20 nm, a superconducting current flows due to the proximity effect. The contact conductor may be configured as a superconductor by cooling to a critical temperature of the contact conductor in this case.

As a thin superconductor sintered body, YBC
In addition to oxide superconductors such as O sintered thin plates, Ta, Nb,
A metal superconductor such as Pb or Sn may be used, and in that case, a SiO ₂ thin plate having a smaller linear expansion coefficient than these metal superconductors may be used as the base layer.

Further, the bimetal lead 14 is connected to YSZ
A YBCO sintered body thin plate 12 may be bonded to both surfaces of the sintered body thin plate 11, and one of the YBCO sintered body thin plates may be used as a signal line and the other YBCO sintered body thin plate may be used as a GND line to form a strip line structure. Thereby, high frequency characteristics are improved.

The method for bonding the sintered thin plates is not limited to heat treatment in a pressurized state, but may be performed using an adhesive such as an epoxy type or a low melting point metal such as In, Pb, or solder. It is good to match,
Further, the inert gas sealed in the glass container 15 is also He gas.
However, the present invention is not limited to this, and Ar gas may be used.

Next, with reference to FIGS. 3 and 4, a description will be given of a process of manufacturing an on-chip type superconducting relay according to a second embodiment of the present invention. Referring to FIG. 3A, first, on a SrTiO ₃ substrate 21 having a thickness of 100 μm to 2 mm, for example, 500 μm, using a laser ablation method, a thickness of 0.1 to 10.0 μm, for example, 1.0 μm.
m, YBCO thin film 22, thickness of 0.1 to 10.0 μm, for example, 1.0 μm SrTiO ₃ thin film 23, thickness of 0.1
Ｂ10.0 μm, for example, 1.0 μm YBCO thin film 2
4, and a thickness of 0.1 to 10.0 μm, for example, 1.0
A YSZ thin film 25 of μm is laminated.

Next, as shown in FIG. 3B, YSZ is performed by an ion milling method using Ar ions using a resist mask (not shown) as a mask.
After patterning the thin film 25 to the YBCO thin film 22 to a width of 1 μm to 1 mm, for example, 20 μm, the YSZ thin film 25 and the YBCO thin film 24 are patterned to a predetermined length using a new resist mask (not shown) as a mask.

Next, after removing the resist mask, the laminate which is not subjected to etching is covered with a new resist mask (not shown) so as to cover the side surfaces, and then, is subjected to 5% hydrofluoric acid. SrTiO ₃ thin film 23 exposed by processing
Is subjected to side etching, and the tip of the upper YBCO thin film 24 has a length of 10 μm to 20 mm, for example, 500 μm.
, Ie, a beam-shaped portion.

In this case, since the etching rate of 5% hydrofluoric acid to SrTiO ₃ is 10 times or more of YBCO and YSZ, only the SrTiO ₃ thin film 23 is selectively etched.

Referring to FIG. 4D, the YBCO thin film 22 as the lower superconductor is patterned by ion milling.
An opening 26 for forming an extraction electrode is formed in the SZ thin film 25.

Next, a YBCO thin film pattern is laminated using a mask sputtering method, and simultaneously with the extraction electrodes 27 and 28,
By forming the superconducting wiring layer 29, an on-chip superconducting relay is completed.

When this superconducting relay is cooled down to the temperature of liquid nitrogen, the YBCO thin film 24 becomes thinner than the YSZ thin film 2 due to the difference in linear expansion coefficient.
5, the beam-like portion curves downward and naturally comes into contact with the YBCO thin film 22, which is the lower superconductor, to be in a normally-on state.

With the superconducting relay turned on, a magnetic field is generated by passing a current through the superconducting wiring layer 29, and the superconducting relay is broken by the magnetic field to a normal conducting state. The current flowing through the YBCO thin film 22 and the YBCO thin film 24 is regarded as a normal conduction current, and the generated heat causes the bimetal structure composed of the YBCO thin film 24 and the YSZ thin film 25 constituting the upper superconducting lead to return to the original state and physically The contact is released and turned off.

In this case, as in the first embodiment, an ideal superconducting switch having a resistance of 0 in the on state and an infinite resistance in the off state can be obtained, and can be formed in a very small size. It can be used as a switch of a superconducting circuit device such as a Josephson circuit device.

Next, with reference to FIG. 5, a modification of the second embodiment of the present invention will be described. In this modification, the superconducting wiring layer 29 in the second embodiment is replaced with a metal wiring layer. Since the other configuration is exactly the same as that of the second embodiment, only the main part will be described.

Referring to FIG. 5, after the same steps as those in FIG. 4D of the second embodiment are performed, YB is formed by using a mask sputtering method.
The lead electrodes 27 and 28 are formed by laminating the CO thin film patterns, and then the metal wiring layer 30 composed of the NiCr thin film pattern is formed by using a mask evaporation method, thereby completing the on-chip type superconducting relay.

With the superconducting relay turned on, Joule heat is generated by passing an electric current through the metal wiring layer 30, and this heat breaks the superconducting relay into a normal conducting state. , YBCO thin film 22
And the current flowing through the YBCO thin film 24 as a normal conduction current,
The YBCO thin film 24 and the YBCO thin film 24 which constitute the upper superconducting lead by heat generated in the BCO thin film 22 and the YBCO thin film 24
The bimetal structure composed of the SZ thin film 25 returns to the original state, the physical contact is released, and the state is turned off.

In this case, the same effect as in the second embodiment is obtained, but in this case, a magnetic field other than Joule heat is generated by the current flowing through the metal wiring layer 30, so that the influence of the heat is reduced by the magnetic field. The position and shape of the metal wiring layer may be set so as to be larger than the influence of the above.

Next, with reference to FIG. 6, a description will be given of a process of manufacturing an on-chip type superconducting relay using a microstrip line structure according to a third embodiment of the present invention. Referring to FIG. 6A, first, on a SrTiO ₃ substrate 31 having a thickness of 100 μm to 2 mm, for example, 500 μm, using a laser ablation method, a thickness of 0.1 to 10.0 μm, for example, 1.0 μm.
m, YBCO thin film 32, thickness 0.01 to 10.0 μm,
For example, a YSZ thin film 33 of 0.5 μm, a thickness of 0.1 to 1
0.0 μm, for example, 1.0 μm YBCO thin film 34,
Sr having a thickness of 0.1 to 20.0 μm, for example, 2.0 μm
TiO ₃ thin film 35, YBCO thin film 36 having a thickness of 0.1 to 10.0 μm, for example, 1.0 μm, thickness 0.01 to 1
A YSZ thin film 37 of 0.0 μm, for example, 0.5 μm, and a YBCO thin film 38 of 0.1 to 10.0 μm, for example, 1.0 μm in thickness are sequentially laminated.

Referring to FIG. 6B, YBC is performed by ion milling using Ar ions with a resist mask (not shown) as a mask.
The O thin film 38 to the YBCO thin film 32 have a width of 1 μm to 1 mm,
For example, after patterning to a thickness of 20 μm, the YBCO thin film 3 is formed using a new resist mask (not shown) as a mask.
8 and the SrTiO ₃ thin film 35 are patterned to a predetermined length.

Next, after removing the resist mask,
5% after covering the unetched laminate so as to cover the side surfaces with a new resist mask (not shown)
SrTi exposed by treating with hydrofluoric acid
O ₃ thin film 35 is subjected to side etching and the upper YBC
The length of the microstrip line consisting of the O thin film 38 / YSZ thin film 37 / YBCO thin film 36 is
A beam-shaped portion of 20 mm, for example, 1 mm is formed.

Next, using ion milling, Y
After patterning the lower microstrip line composed of the BCO thin film 34 / YSZ thin film 33 / YBCO thin film 32, the extraction electrodes 39 and 40 and the ground plane, that is, the YBCO thin film 38 and the Y which constitute the GND conductor, and Y
By forming a GND connection electrode 41 for connecting the BCO thin film 32 and forming a superconducting wiring layer serving as a coil or a metal wiring layer made of NiCr or the like (not shown) serving as a heating element, a microstrip line can be used. Completed on-chip type superconducting relay.

When this superconducting relay is cooled down to the temperature of liquid nitrogen, the YBCO thin films 36 and 38 have a YSZ
Although it is smaller than the thin film 37, since the thickness of the upper YBCO thin film 38 is smaller than the thickness of the lower YBCO thin film 36, the beam portion bends downward to form the signal line of the lower microphone strip line. The thin film 34 naturally comes into contact with the thin film 34 to be in a normally-on state.

With the superconducting relay turned on, a current is passed through a superconducting wiring layer or a metal wiring layer (both not shown), whereby the superconducting state of the superconducting relay is broken, and the YBCO thin film 36 and Since the current flowing through the YBCO thin film 34 becomes a normal conduction current, the heat generated thereby causes the upper microstrip line of the bimetal structure to return to its original state, release physical contact, and turn off.

In this case, as in the second embodiment, an ideal superconducting switch having a resistance of 0 in the on state and an infinite resistance in the off state can be obtained, and a microstrip line structure is employed. As a result, the high-frequency characteristics are improved.

In the third embodiment,
In order to form a bimetal structure, the thickness of the GND line forming the upper microstrip line is made thinner than the signal line, but may be the same thickness.
It is necessary to change the growth conditions so that the coefficient of linear expansion differs.

For example, the film forming conditions of the YBCO thin film 36 serving as a signal line are set to gas containing 13.3 Pa and argon containing 50% oxygen gas, and the film forming condition of the YBCO thin film 38 serving as a GND line is set to gas pressure. YB by changing the gas pressure as argon containing 50% oxygen gas at 54 Pa
The coefficient of linear expansion of the CO thin film 36 can be made larger than the coefficient of linear expansion of the YBCO thin film 38.

As another modification, the GND line forming the upper microstrip line may be formed of a superconducting material having a smaller linear expansion coefficient than the YBCO thin film 36 serving as the signal line.

Next, a manufacturing process of an on-chip type superconducting relay using a coplanar type microstrip line structure according to a fourth embodiment of the present invention will be described with reference to FIGS. In addition, the figure on the left side of FIG. 7A is a plan view, and the figure on the right side is a dashed line A-
FIG. 7 is a cross-sectional view taken along the line A ′, and FIGS.
The figure on the left side of (d) is also a plan view, each upper right figure is a cross-sectional view along the dashed line AA 'in the left figure, and each lower right figure is a dashed line BB' in the left figure. It is sectional drawing along.

Referring to FIG. 7A, first, on a SrTiO ₃ substrate 51 having a thickness of 100 μm to 2 mm, for example, 500 μm, using a laser ablation method, a thickness of 0.1 to 10.0 μm, for example, 1.0 μm.
m, YSZ thin film 52, thickness of 0.1 to 10.0 μm, for example, 1.0 μm YBCO thin film 53, thickness of 0.1 to 2,
0.0 μm, for example, 2.0 μm SrTiO ₃ thin film 5
4, a YBCO thin film 55 having a thickness of 0.1 to 10.0 μm, for example, 1.0 μm, and a thickness of 0.1 to 10.0 μm;
For example, a 1.0 μm YSZ thin film 56 is sequentially laminated.

Next, a resist film 57 is applied to form a pattern such that a region surrounded by a plurality of slits 58 provided in the resist film 57 becomes a signal superconducting wiring.

Next, referring to FIG. 7B, the isolation grooves 59 are formed by etching the YSZ thin films 56 to 53 using the resist film 57 as a mask by ion milling using Ar ions.

Referring to FIG. 8C, after removing the resist film 57, 0.1% H
By performing a wet etching with a Cl solution and side-etching only the YBCO films 52 and 55, a slit 58 along a dashed line BB 'is formed.
The YBCO films 52 and 55 existing between them are removed to form side etching portions 60.

As shown by the thick dashed line in the plan view on the left side, Y
The BCO films 52 and 55 can completely separate the central signal superconducting wiring layer and the annular GND conductor through the separation groove 59.

[0072] FIG. 8 (d) see Then, after coating the laminate is not subjected to etching by new resist film 61 as side also cover, SrTiO ₃ which is exposed by treatment with 5% hydrofluoric acid
The beam-like portion is formed by removing the thin film 54 by performing side etching.

Next, although not shown, similarly to the third embodiment, a superconducting wiring layer serving as a coil or a metal wiring layer made of NiCr or the like serving as a heating element is formed, and an extraction electrode and a GND extraction electrode are formed. By doing so, an on-chip type superconducting relay using a coplanar type microstrip line structure is completed.

Also in this case, when the superconducting relay is cooled to the temperature of liquid nitrogen, the YBCO thin film 55 shrinks from the YSZ thin film 56 due to the difference in linear expansion coefficient, so that the beam-like portion is bent downward and the lower microphone is bent. It naturally comes into contact with the YBCO thin film 52 constituting the signal line of the strip line to be in a normally-on state.

Further, since the upper and lower GND conductors are naturally electrically connected to each other by bending, a GND connection electrode for connecting the GND conductors becomes unnecessary.

Although the YSZ thin film 56 is provided with a slit 58, since the whole is integrated, the YB
The CO thin film 55 has a separation groove 59 and a side etching portion 60.
YSZ thin film 56 can stably support the separated YBCO thin film 55 even if it is separated.

With the superconducting relay turned on, a current is passed through a superconducting wiring layer or a metal wiring layer (both not shown), so that the superconducting state of the superconducting relay is broken and the YBCO thin film 55 Since the current flowing through the YBCO thin film 52 becomes a normal conduction current, the heat generated thereby causes the upper microstrip line of the bimetal structure to return to the original state, release physical contact, and turn off.

In this case, as in the third embodiment, an ideal superconducting switch having a resistance of 0 in the on state and an infinite resistance in the off state can be obtained. Since the line structure is employed, the high-frequency characteristics are improved, and the GND connection electrode for connecting the GND electrodes is not required, so that the wiring structure is simplified.

Although the embodiments have been described above, in the present invention, no magnetic field is applied in the ON state, so that there is no problem that the superconducting critical current is reduced by the magnetic field. Since it is not necessary to use a magnetic material as the base layer, the superconductivity of the superconductor thin film does not deteriorate due to the magnetic field of the magnetic material, but this does not prevent the use of the magnetic material as the base layer.

Further, the superconductor thin plate which is an object of the present invention is not limited to a YBCO thin film, but Bi ₂ Sr ₂ Ca ₁ Cu which exhibits high-temperature superconducting characteristics like YBCO.
_{2 O y, Tl 2 Ba 2} Ca 2 Cu 3 O z, LnBa 2 C
An oxide superconductor such as u ₃ O _7-x (where Ln is a lanthanoid) may be used. When such an oxide superconductor is used, the base layer and the spacer layer may be used. Also, by using an oxide, it is possible to continuously form a film using the same growth apparatus, so that there is an advantage that the manufacturing process is simplified.

The superconductor thin plate is not limited to the oxide superconductor thin film, but may be Ta, Nb, Pb or
A metal superconductor such as Sn may be used. In this case, a SiO ₂ thin plate having a smaller linear expansion coefficient than these metal superconductors may be used as the base layer.

For example, the coefficient of linear expansion of YBCO is 1.4 ×
, Whereas the a 10 ^-5 ° C., Ta is 0.6 × 10 ^-5 ℃,
Nb is 0.9 × 10 ^-5 ° C, and SrTiO _{3 as} an insulator is used.
Is 1.0 × 10 ^-5 ° C., MgO is 1.2 × 10 ^-5 ° C., Si
O ₂ is 0.01 × 10 ⁻⁵ ° C., YSZ is 1.0 × 10 ⁻⁵ ° C.
And Au of the metal is 1.3 × 10 ⁻⁵ ° C. and Pt is
Since is a 0.9 × 10 ^-5 ° C., in consideration of the linear expansion coefficient, the linear expansion coefficient of the base layer may be used becomes smaller combination than the linear expansion coefficient of the superconductor thin film or the superconductor thin.

[0083]

According to the present invention, since a normally-on superconducting relay is formed by using a bimetal lead structure, there is no deterioration due to a magnetic field, the resistance is 0 in an on state, and the resistance is infinite in an off state. An ideal superconducting switch can be realized, and greatly contributes to the development of superconducting power transmission or high-speed communication transmission.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a basic configuration of the present invention.

FIG. 2 is an explanatory diagram of the first embodiment of the present invention.

FIG. 3 is an explanatory diagram of a manufacturing process partway through a second embodiment of the present invention.

FIG. 4 is an explanatory view of a manufacturing process after FIG. 3 of the second embodiment of the present invention.

FIG. 5 is an explanatory diagram of a modified example of the second embodiment of the present invention.

FIG. 6 is an explanatory diagram of a manufacturing process according to a third embodiment of the present invention.

FIG. 7 is an explanatory diagram of a manufacturing process partway through a fourth embodiment of the present invention.

FIG. 8 is an explanatory diagram of a manufacturing process of the fourth embodiment of the present invention after FIG. 7;

FIG. 9 is an explanatory view of a conventional superconducting reed switch.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Base layer 2 Superconductor thin film 3 Contact conductor 4 Bimetal lead 5 Superconducting current 11 YSZ sintered thin plate 12 YBCO sintered thin plate 13 Au thin film 14 Bimetal lead 15 Glass container 16 Superconducting wire 17 Metal wire 21 SrTiO ₃ substrate Reference Signs List 22 YBCO thin film 23 SrTiO ₃ thin film 24 YBCO thin film 25 YSZ thin film 26 Opening 27 Lead electrode 28 Lead electrode 29 Superconducting wiring layer 30 Metal wiring layer 31 SrTiO ₃ substrate 32 YBCO thin film 33 YSZ thin film 34 YBCO thin film 35 SrTiO ₃ thin film 36 37 YSZ thin film 38 YBCO thin film 39 Lead electrode 40 Lead electrode 41 GND connection electrode 51 SrTiO ₃ substrate 52 YSZ thin film 53 YBCO thin film 54 SrTiO ₃ thin film 55 YBCO thin film 56 YSZ thin film 57 resist film 58 Slit 59 Separation groove 60 Side etching part 61 Resist film 71 Magnetic thin plate 72 Superconductor thin film 73 Superconductive lead 74 Glass tube

Claims (8)

[Claims] 1. A superconducting relay in which a pair of superconducting leads having a superconducting thin film are arranged such that said superconducting thin films are in electrical contact with each other in a normal state at an operating temperature. The superconductor lead is composed of a bimetal lead in which a superconductor thin film and a non-superconducting base layer are laminated near the critical temperature of the superconductor thin film, and the criticality of the superconductor thin film is A superconducting relay, wherein the thermal expansion coefficient of the base layer is smaller than the thermal expansion coefficient of the superconductor thin film near a temperature. 2. The superconducting relay according to claim 1, wherein a resistor for generating heat is arranged near a contact portion where the superconducting thin films are in electrical contact with each other. 3. The superconducting relay according to claim 1, wherein a coil for generating a magnetic field is arranged near a contact portion where the superconducting thin films are in electrical contact with each other. 4. The superconducting relay according to claim 1, wherein said pair of superconductor leads are formed on the same support substrate. 5. A superconductor thin film forming one of the superconductor leads is provided on the same support substrate, and the bimetal lead having a beam-like portion is placed so that the superconductor thin film is on the lower surface side. It is arranged oppositely via a spacer layer,
5. The superconducting relay according to claim 4, wherein said superconducting thin films 2 are in electrical contact with each other at least at a tip of said beam-shaped portion in a normal state at an operating temperature. 6. The superconductor lead according to claim 1, wherein the superconductor lead has a three-layer stripline structure of superconductor / insulator / superconductor. The superconducting relay according to 1. 7. The superconducting relay according to claim 1, wherein the superconductor lead has a coplanar stripline structure. 8. The superconducting relay according to claim 1, wherein the superconductor thin film forming the superconductor lead is an oxide superconductor thin film.