JPH05160453A - Superconductive quantum interference device - Google Patents

Abstract

PURPOSE:To provide a title device of high sensitivity with a small device area and a reduced parasitic component, a title device which can detect a difference in flux changes in an arbitrary space, and a title device improved in flux transmittance to any of superconducting coils for detecting magnetic flux different in inductance values. CONSTITUTION:Superconducting coils 12 for inputting magnetic flux with spiral parts produced in two or more wiring layers made of a superconductor thin film are arranged; superconducting coils 12 for inputting magnetic flux which generate magnetic fields almost in a substantially reverse direction to a superconducting ring 11 are arranged by sandwiching the superconducting ring 11; or a plurality of superconducting coils for inputting magnetic flux different in inductance are arranged.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a superconducting quantum interference device for detecting a minute magnetic flux.
rference Device; hereinafter abbreviated as SQUID).

[0002]

2. Description of the Related Art SQUID utilizes the property of superconductivity to
It is an element that can detect a minute magnetic field. For SQUIDs for detecting minute magnetic fields, see
E, Transaction on Electron Devices, ED 27, No. 10 (1980
Year) 1986 to 1908 (IEEE. Tran
s. Electron Devices, ED27, No. 10 (198
0) PP. 1896-1908). In the magnetometer using the SQUID, there is a case where a method of detecting a magnetic flux through an input circuit formed of a superconducting closed circuit is generally used without directly detecting the magnetic flux with a superconducting ring having a Josephson junction. FIG. 8 shows a schematic diagram of the configuration of the magnetometer.

Reference numeral 11 in FIG. 8 is a Josephson junction (hereinafter, J
A superconducting ring having a portion (abbreviated as J) (hereinafter referred to as a superconducting ring), 82 is a superconducting coil for inputting magnetic flux, and 83
Is a superconducting wire, 84 is a superconducting coil for detecting magnetic flux of the first differential type, 85 is JJ, 86 is a lower electrode, 87 is an upper electrode, 88 is a superposition of slits of the superconducting ring 11,
89 is an opening of the superconducting ring 11. Further, in FIG. 8, the number of turns of the superconducting coil 82 for magnetic flux input is simplified, and interlayer insulating layers, resistors, feedback coils and the like which are not related to the present invention are omitted. This also applies to other figures. The superposition of slits 88 is for reducing the parasitic inductance generated in the superconducting ring 11.

The external magnetic flux is the superconducting coil 8 for detecting the magnetic flux.
4 and consequently induces a shielding current in the superconducting closed circuit. The current flows into the superconducting coil 82 for magnetic flux input, which is magnetically coupled to the superconducting ring 11, and transmits the change in the magnetic flux to the superconducting ring 11. In order to increase the degree of magnetic coupling between the superconducting coil 82 for inputting the magnetic flux and the superconducting ring 11, usually, a method of laminating both of them on one substrate is adopted. The superconducting coil 82 for magnetic flux input of the SQUID of this structure is mainly of a spiral type, and this spiral part is formed of a superconducting thin film on either the upper side or the lower side of the superconducting ring 11 via an insulating film. It is made of wiring layers.

The magnetic flux transmissibility of the magnetometer depends on the inductance values of the superconducting coil 84 for detecting the magnetic flux, the superconducting coil 82 for inputting the magnetic flux, and the superconducting ring 11. The magnetic flux transmissibility between the superconducting coil 84 for detecting magnetic flux and the superconducting coil 82 for inputting magnetic flux is such that, when the inductance of the superconducting wiring 83 connecting them is ignored, the superconducting coil 84 for detecting magnetic flux and the superconducting coil for inputting magnetic flux are input. When the inductances of the superconducting coils 82 are equal, the maximum value is obtained. Therefore, it is desirable to manufacture the element so that the superconducting coil 84 for detecting the magnetic flux and the superconducting coil 82 for inputting the magnetic flux have substantially the same inductance. Superconducting coil 8 for magnetic flux input
In order to make the inductance of No. 2 and the inductance of the magnetic flux detecting superconducting coil 84 substantially equal, a method such as selecting the number of turns of the magnetic flux inputting superconducting coil 82 is used.

[0006]

In order to improve the magnetic flux transmissibility of the superconducting coil 84 for detecting the magnetic flux, the superconducting coil 82 for inputting the magnetic flux, and the superconducting coil 82 for inputting the magnetic flux and the superconducting ring 11, the above-mentioned conventional technique is used. In addition, there is a problem that the number of turns of the superconducting coil 82 for magnetic flux input is increased, the area of the element is increased accordingly, parasitic components such as parasitic inductance and parasitic capacitance are increased, and the sensitivity of the element is reduced.

Further, as the area of the element, that is, the area of the superconducting ring 11 increases, the voltage step due to the standing wave standing on the superconducting ring 11 occurs on the low voltage side, so that the output voltage decreases. However, there was a problem that the sensitivity was lowered.

Further, in the magnetometer constructed by using the superconducting quantum interference device according to the above-mentioned conventional technique, the magnetic field gradient in a specific space can be obtained, but the magnetic field gradient in an arbitrary space cannot be obtained. there were.

Furthermore, the above-mentioned conventional technique has a problem that only a specific magnetic flux detecting superconducting coil 84 having an inductance matching the inductance of the magnetic flux inputting superconducting coil 82 has a good magnetic flux transmissibility.

A first object of the present invention is to provide a highly sensitive superconducting quantum device having a small element area and a reduced parasitic component while having an inductance similar to that of a conventional superconducting coil for inputting magnetic flux of an element. It is to provide an interference element.
A second object of the present invention is to provide a superconducting quantum interference device capable of detecting the difference in magnetic flux change in an arbitrary space. A third object of the present invention is to provide a superconducting quantum interference device capable of improving the magnetic flux transmissibility as compared with the above-mentioned prior art, even when any of a plurality of types of superconducting coils for magnetic flux detection having different inductance values is connected. To provide.

[0011]

[Means for Solving the Problems] The first object is to:
(1) A superconducting ring having a Josephson junction provided on a substrate, and a superconducting coil for magnetic flux input for magnetically coupling to the superconducting coil for magnetic flux detection. In the superconducting quantum interference device, the superconducting quantum interference device for magnetic flux input is divided into a plurality of wiring layers made of a superconducting thin film, (2) the superconducting quantum interference device according to 1 above. In the element, the plurality of wiring layers made of a superconductor thin film forming the superconducting coil for inputting the magnetic flux are arranged above or below the superconducting ring via an insulating film. (3) In the superconducting quantum interference device described in (1) or (2) above, among the plurality of wiring layers made of a superconductor thin film forming the superconducting coil for inputting the magnetic flux. A superconducting quantum interference device characterized in that at least two layers have a spiral shape, (4) in the superconducting quantum interference device according to the above 1 or 2, at least two layers out of a plurality of wiring layers made of the superconductor thin film The superconducting coil for inputting the magnetic flux, the superconducting quantum interference device, wherein the magnetic flux is coupled to the superconducting ring to generate a circulating current,
(5) In the superconducting quantum interference device as described in 1 or 2, the superconducting coil for magnetic flux input formed in at least two layers of the plurality of wiring layers made of the superconductor thin film is provided in an opening of the superconducting ring. A superconducting quantum interference device, characterized in that the superconducting quantum interference device is arranged so as to generate interlinking magnetic fluxes; (6) In the superconducting quantum interference device according to 1 above, the superconducting thin film forming the superconducting coil for inputting the magnetic flux. A plurality of wiring layers consisting of the superconducting quantum interference device, wherein the wiring layers are arranged above and below the superconducting ring via insulating films, and (7) the superconducting quantum interference device according to the above 6, A plurality of wiring layers made of a superconducting thin film forming a superconducting coil for use in at least one layer above and below the superconducting ring, each of which has a spiral shape. Is achieved by a superconducting quantum interference device characterized.

The second object is (8) a superconducting ring having a Josephson junction provided on a substrate, and a superconducting ring sandwiched between the superconducting ring and the superconducting ring. , Two superconducting coils for magnetic flux input, which are magnetically coupled to the superconducting ring and are connected to the superconducting coils for magnetic flux detection, respectively. A superconducting quantum interference device having a structure for generating a magnetic field substantially in a direction substantially opposite to a superconducting ring, (9) the superconducting quantum interference device according to the above 8, wherein the two magnetic flux inputs are used. The superconducting coil has substantially the same magnetic flux transmissibility as that of the superconducting ring. (10) The superconducting quantum interference device according to the above 8 or 9, wherein: A superconducting coil for use in a superconducting quantum interference device, wherein the superconducting quantum interference device is divided into a plurality of wiring layers made of a superconductor thin film. (11) The superconducting quantum interference device according to the above 10, At least two layers of a plurality of wiring layers formed of a superconductor thin film forming a coil are spiral-shaped, (12) the superconducting quantum interference device according to the above 10, The superconducting coil for inputting the magnetic flux, which is formed by at least two layers out of a plurality of wiring layers made of a superconducting thin film, is arranged as if a magnetic flux is coupled to the superconducting ring to generate a circulating current. Characteristic superconducting quantum interference device, (13) above 1
0. In the superconducting quantum interference device according to 0, the superconducting coil for magnetic flux input formed by at least two layers of the plurality of wiring layers made of the superconducting thin film generates a magnetic flux interlinking with the opening of the superconducting ring. This is achieved by a superconducting quantum interference device characterized in that it is arranged in the same manner.

The third object is (14) a superconducting ring having a Josephson junction provided on a substrate,
In a superconducting quantum interference device magnetically coupled to this, and having a superconducting coil for magnetic flux input to be connected to a superconducting coil for magnetic flux detection, the superconducting coil for magnetic flux input has a plurality of different inductances. A superconducting quantum interference device, characterized in that
5) In the superconducting quantum interference device as described in 14 above, the superconducting coil for inputting the magnetic flux is divided into a plurality of wiring layers each made of a superconductor thin film, and arranged. ) In the superconducting quantum interference device as described in 15 above, at least two layers out of a plurality of wiring layers made of a superconducting thin film forming the superconducting coil for inputting the magnetic flux have a spiral shape. (17) In the superconducting quantum interference device as described in (17) above, the superconducting coil for magnetic flux input formed by at least two layers of the plurality of wiring layers made of the superconducting thin film is provided with respect to the superconducting ring. A superconducting quantum interference device, characterized in that it is arranged as if magnetic fluxes are combined to generate a circulating current, (18) above 15
In the superconducting quantum interference device described above, the superconducting coil for magnetic flux input formed by at least two layers of the plurality of wiring layers made of the superconducting thin film is such that a magnetic flux interlinks with the opening of the superconducting ring. Is achieved by a superconducting quantum interference device.

[0014]

The SQUID of the present invention is provided with a superconducting coil for magnetic flux input, which is divided into a plurality of wiring layers made of a superconducting thin film to reduce the element area.
At the same time, it is possible to reduce parasitic components such as parasitic inductance and parasitic capacitance generated in the element. This is
The following acts for increasing the sensitivity of the device. One of the factors that hinder the enhancement of the sensitivity of the element is the voltage step that occurs in the current-voltage characteristics. This voltage step is due to resonance (LC resonance) due to inductance and capacitance in the element and to the superconducting ring. The cause is resonance due to standing waves.
The position of the voltage step due to the LC resonance occurs on the lower voltage side as the capacitance and inductance of the element increase. Therefore, by reducing the parasitic inductance and the parasitic capacitance of the element, the voltage generated by the voltage step due to the LC resonance can be set to a higher voltage side and can be separated from the operating range of the element, so that the element has high sensitivity. be able to. On the other hand, the voltage step due to the resonance of the standing wave standing on the superconducting ring is generated on the lower frequency side as the wavelength standing on the element is longer.
That is, the larger the element area, the lower the voltage will occur. Therefore, if the area of the element is made smaller, the wavelength standing on the superconducting ring becomes shorter, so the voltage at which the voltage step is generated can be made higher and the sensitivity can be improved because it can be separated from the operating range of the element. can do.

Further, two magnetic flux input superconducting coils for generating magnetic fields in substantially opposite directions to the superconducting ring are provided so as to be electrically insulated from the superconducting ring by sandwiching the superconducting ring. This makes it possible to detect the amount corresponding to the difference in the magnetic flux changes detected by the magnetic flux detecting superconducting coils connected to the respective magnetic flux inputting superconducting coils.

Further, by providing a plurality of superconducting coils for inputting magnetic flux having different inductances, even if the inductance of the superconducting coil for detecting magnetic flux changes, among the plurality of superconducting coils for inputting magnetic flux, , By using the superconducting coil for magnetic flux input with the optimum inductance,
It is possible to improve the magnetic flux transmissibility as compared with the conventional element having only one piece.

[0017]

EXAMPLES (Comparative Example) First, a conventional superconducting quantum interference device will be described as a comparative example. FIG. 8 shows a superconducting ring 1.
1 above the wiring layer 60 in a single wiring layer made of a superconductor thin film.
Superconducting coil 8 for magnetic flux input in which spiral part of winding is created
It is a schematic diagram which shows the state which connected the superconducting coil 84 for magnetic flux detection to the superconducting quantum interference element which has arrange | positioned 2 using the superconducting wiring 83. The manufacturing method of this element is as follows. The substrate used was a Si wafer whose surface was thermally oxidized. A Nb film (thickness: 200 nm) is deposited on this surface by the DC magnetron sputtering method, and the superconducting ring 1 is formed by the reactive ion etching method using the photoresist as a mask material.
A pattern of 1 was formed.

Next, the process proceeds to the step of forming an interlayer insulating film. After that, the SiO2 film is used as the interlayer insulating film.
A pattern was formed by the lift-off method. Interlayer insulation film (thickness;
Although not shown in FIG. 8, a MoNx film (thickness: 100 nm) is formed by a DC magnetron sputtering method as a resistance film after the formation of 300 nm) and by a reactive ion etching method using a photoresist as a mask material. A pattern was formed. Next, an interlayer insulating film (thickness: 180
nm), and then as a superposition 88 of the lower electrode 86 and the slit, an Nb-NbN laminated film (thickness: 250).
nm) was formed by a DC magnetron sputtering method, and a pattern was formed by a reactive ion etching method using a photoresist as a mask material. Then, an interlayer insulating film (thickness: 320 nm) provided with a window (junction window; 5 μm square) for forming a tunnel barrier layer (JJ) was formed thereon.

Next, the spiral portion (60 turns) of the superconducting coil 82 for inputting the magnetic flux and the upper electrode 87 are made of photoresist.
Of the tunnel barrier layer (JJ) 85 (N) is formed on the surface of the lower electrode of the junction window by the high frequency plasma oxidation method after the pattern is formed.
bOx) is formed, and then Pb alloy (thickness: 450;
nm) was deposited. Then, the spiral portion of the superconducting coil 82 for magnetic flux input and the pattern of the upper electrode 87 were formed by the lift-off method.

The area of the thus-produced element was about (1.31 cm) ² , and the inductance of the superconducting ring 11 was measured and found to be 104 pH. Since the inductance obtained from the length of one side of the opening 89 of the superconducting ring 11 is 39 pH, this element has 65
There was a pH parasitic inductance. The inductance of the superconducting coil 82 for inputting the magnetic flux is about 380n.
It was H.

(Embodiment 1) A first embodiment of the superconducting quantum interference device of the present invention will be described. FIG. 1 is a schematic diagram of an element in which a superconducting coil 12 for magnetic flux input is arranged above a superconducting ring 11 and is divided into two wiring layers made of a superconductor thin film via an insulating film to form a spiral portion. In this element,
A 35-turn superconducting coil for magnetic flux input is formed in each layer. In addition, the manufacturing method of the element is that an interlayer insulating film is provided between the wiring layers made of two superconducting thin films forming the spiral portion of the superconducting coil 12 for magnetic flux input,
It is substantially the same as the element of the comparative example. The inductance of the magnetic flux input superconducting coil 12 of this element is about 390 nH, which is substantially the same as the magnetic flux input superconducting coil 82 of the element of the comparative example. However, the area of the device was about (0.81 cm) ² , and the device area was about 2.6 times smaller than that of the device of the comparative example. In addition, the parasitic inductance was also reduced to about half.

Further, as shown in FIG. 2, a superconducting coil 22 for magnetic flux input, in which a spiral portion is formed by dividing the superconducting thin film into three wiring layers, is arranged above the superconducting ring 11, As shown in FIG. 3, the same effect can be obtained by disposing the superconducting coil 32 for magnetic flux input in which the spiral portion is formed by dividing the superconducting thin film into four wiring layers above the superconducting ring 11. .. Table 1 summarizes the area of the superconducting ring of each of these elements, the parasitic inductance, the value of the inductance of the superconducting coil for inputting the magnetic flux, and the like.

[0023]

[Table 1]

(Embodiment 2) Another embodiment of the present invention will be described. FIG. 4 is a schematic diagram of an element in which a superconducting coil 42 for magnetic flux input is disposed below the superconducting ring 11 in which a spiral portion is formed by dividing into two wiring layers made of a superconductor thin film. A 35-turn superconducting coil for magnetic flux input is formed in each layer. The method of manufacturing the element is the same as that of the element of the example. Similar to the element of Example 1, this element also has a superconducting coil 42 for magnetic flux input having an inductance of substantially the same value as the element of the comparative example, but the element area is about 2. It has been reduced to one sixth and the parasitic inductance has been reduced to about one half. Similar to the element of Example 1, the same effect can be obtained even if the spiral portion of the superconducting coil for magnetic flux input is divided into three or more wiring layers made of a superconductor thin film below the superconducting ring. .. Table 1 summarizes the area of the superconducting ring of each of these elements, the parasitic inductance, the value of the inductance of the superconducting coil for inputting the magnetic flux, and the like.

(Embodiment 3) Another embodiment of the present invention will be described. FIG. 5 shows a total of two superconducting thin films including a superconducting thin film above the superconducting thin film 11 and a single wiring layer below the superconducting thin film 11 and a superconducting thin film below the superconducting thin film. It is a schematic diagram of the element which has arrange | positioned the superconducting coil 52 for magnetic flux input which divided the wiring layer and produced the spiral part. In each layer, a superconducting coil for inputting magnetic flux is wound 35 times. The manufacturing method of the element is substantially the same as that of the element of Example 1. Similar to the elements of Example 1 and Example 2, this element also had an element area of about 2.6 times smaller than the element of the comparative example, and the parasitic inductance was also reduced to about 1/2. Further, in the third embodiment, the upper and lower wirings are connected to form the coil through the opening 89 of the superconducting ring 11, but the wirings may be connected outside the superconducting ring 11. Also, the same effect can be obtained even if the number of wiring layers made of a superconductor thin film sandwiching the superconducting ring 11 to form a spiral portion is different between the upper and lower portions. Table 1 summarizes the area of the superconducting ring of each of these elements, the parasitic inductance, the value of the inductance of the superconducting coil for inputting the magnetic flux, and the like.

In the elements of these examples, the number of turns of the superconducting coil for magnetic flux input in each layer is the same, but it is clear that the same effect can be obtained even if the number of turns in each layer is different. Further, as the cause of the parasitic capacitance that occurs in the element, it is considered that the capacitance due to the superposition of the slits of the superconducting ring or the capacitance between the superconducting ring and the superconducting coil for magnetic flux input, etc. The element is
Since the element area can be reduced, the parasitic capacitance is also reduced.

Further, although these elements were manufactured by using Nb or Pb alloy, the same effect can be obtained by manufacturing the part made of Pb alloy by Nb or oxide superconductor. It is clear that Further, although the first, second and third embodiments of the present invention relate to an element having two JJs, it is clear that the same effect can be obtained even for an element having only one JJ. is there.

(Embodiment 4) Another embodiment of the present invention will be described. In FIG. 6, a superconducting coil 621 for magnetic flux input is provided above the superconducting ring 11 in which a spiral portion of 60 turns is formed in one wiring layer made of a superconductor thin film via an insulating film, and the insulating film is provided below. A superconducting quantum interference device provided with a superconducting coil 622 for magnetic flux input in which a spiral portion of 60 turns is formed in one wiring layer made of a superconducting thin film is connected to the superconducting coil for magnetic flux detection by using superconducting wiring. It is a schematic diagram which shows the state. In this device, the thicknesses of the superconducting ring 11 and the interlayer insulating film of the superconducting coil 621 for magnetic flux input and the interlayer insulating film of the superconducting ring 11 and the superconducting coil 622 for magnetic flux input are approximately the same (within ± 5% error). The superconducting coil 621 for inputting the magnetic flux and the superconducting coil 622 for inputting the magnetic flux have substantially the same inductance (within an error of ± 5%). That is, the design conditions such as the number of turns and the line width were the same, and the manufacturing conditions were substantially the same.

The manufacturing method of this element is almost the same as that of the element of the comparative example. However, superconducting coils 621 and 62 for magnetic flux input, which are formed above and below the superconducting ring 11.
2 and the superconducting ring 11 have the same thickness of the interlayer insulating film, the superconducting coil 622 for magnetic flux input and the interlayer insulating film below the superconducting ring 11 are formed, and then the resist is spin-coated to etch back. Then, the surface was flattened. Further, the size of the superconducting ring 11, the number of turns and the line width of the superconducting coils 621 and 622 for magnetic flux input, and the thickness of the interlayer insulating film between the superconducting coils 621 and 622 for magnetic flux input and the superconducting ring 11 are designed. The conditions were the same as those of the device of the comparative example.

When the current-voltage characteristics of the device of this example and the device of the comparative example shown in FIG. 8 were measured, the results were substantially the same (within an error of ± 5%) for both devices. Further, in the element of the present example, by passing an alternating current through the upper superconducting coil 621 for magnetic flux input, the voltage-magnetic flux characteristic was measured, and also for the lower coil, the voltage-magnetic flux characteristic was measured, With both coils, almost the same results (within an error of ± 5%) were obtained. Similarly, with respect to the element of the comparative example, the voltage-magnetic flux characteristic was measured by applying an alternating current to the superconducting coil 82 for inputting the magnetic flux. The result of (within) was obtained.

A superconducting coil 84 for magnetic flux input of the device of the comparative example was connected to a superconducting coil 84 for primary differential type magnetic flux detection by using a superconducting wiring 83. Further, the element of this example has a coil diameter substantially the same as the first-order differential type magnetic flux detection superconducting coil 84 connected to the element of the comparative example (within an error of ± 5%). The magnetic flux detection superconducting coils 641 and 642 are respectively connected to the superconducting wiring 631 and
And 632 are used to input the superconducting coil 62 for inputting the magnetic flux.
1 and 622. The wiring length and the like were adjusted so that the inductance of the superconducting wiring between the superconducting coil for detecting magnetic flux and the superconducting coil for inputting magnetic flux was equal in the element of the comparative example and the element of the present example. The two non-differential type magnetic flux detecting superconducting coils of the element of this embodiment are equal to the distance between the two ring portions forming the first-order differential type magnetic flux detecting superconducting coil 84 of the comparative example element. 641 and 642 are separated from each other, and the non-differential type magnetic flux detection superconducting coils 641 and 642 are arranged so that their centers are on the same axis, and both coils are substantially parallel to each other. did. When the detection of the magnetic field generated by the current was attempted with both the elements in this state, almost the same result (the difference was within ± 5%) could be obtained. Therefore, when the two magnetic flux detecting superconducting coils were placed in an arbitrary space, the device of this example could detect an amount equal to the difference in the magnetic flux changes detected by each coil.

In this embodiment, the upper and lower magnetic flux input superconducting coils 621 and 622 are made of a single wiring layer made of a superconductor thin film to form the spiral portion. As described above, when the spiral portion of the superconducting coil for inputting the magnetic flux was divided into two, three, or four wiring layers made of a superconductor thin film, the same effect was obtained.

Further, in this embodiment, by making the inductances of the superconducting coils 621 and 622 for magnetic flux input and the interlayer insulating film between the superconducting ring 11 and the superconducting ring 11 equal, the superconducting coils 621 for magnetic flux input arranged above are made equal to each other. The magnetic flux transmissibility with the superconducting ring 11 and the magnetic flux transmissivity between the superconducting coil 622 for magnetic flux input and the superconducting ring 11 arranged below are made equal, but if the magnetic flux transmissivities become equal,
The inductance of the upper and lower coils and the value of the interlayer insulating film may be changed appropriately.

If the upper and lower magnetic flux transmissivities are different or if strict measurement is desired, a standard element may be prepared and correction may be made by comparison with the standard element. Also,
Although these elements were manufactured using Nb or Pb alloy,
It is clear that the same effect can be obtained even if the part made of the b alloy is made of Nb or the oxide superconductor. Further, although the embodiment of the present invention relates to a device having two Josephson junctions, it is obvious that the same effect can be obtained also for a device having only one Josephson junction.

(Fifth Embodiment) Another embodiment according to the present invention will be described. In FIG. 7, a superconducting coil 721 for magnetic flux input of 60 turns is provided above the superconducting ring 11 and further above the superconducting coil 721.
It is a schematic diagram of the element which produced the superconducting coil 722 for magnetic flux input of 0 winding, and further produced the superconducting coil 723 for magnetic flux input of 20 winding above it. The method of manufacturing the element is substantially the same as that of the element of the comparative example. All of these superconducting coils for magnetic flux input are independent, and their inductances are about 380 nH (60 turns) and about 170 nH, respectively.
(40 windings) and about 42 nH (20 windings). Therefore, since the magnetic flux input superconducting coil to be used can be selected according to the inductance of the magnetic flux detecting superconducting coil, the magnetic flux transmissibility can be improved as compared with the element of the comparative example. As an example, the superconducting ring has an inductance of 104 pH, the superconducting ring and the superconducting coil for magnetic flux input have a magnetic flux transmissibility of 0.8, and the superconducting coil for detecting magnetic flux has an inductance of 400 nH and 200 n.
Table 2 summarizes the calculation results of the magnetic flux transmissibility from the superconducting coil for magnetic flux detection to the superconducting ring in the element of FIG. 7 and the element of the comparative example at H and 100 nH. However, the inductance of the superconducting wiring connecting the superconducting coil for detecting magnetic flux and the superconducting coil for inputting magnetic flux was ignored.

[0036]

[Table 2]

In this embodiment, a superconducting coil for magnetic flux input having a spiral portion is provided in one wiring layer made of a superconductor thin film. However, as in the first embodiment, two layers, three layers or four layers are provided.
The same effect was obtained when a superconducting coil for magnetic flux input, which was created by dividing the spiral part in the wiring layer, was provided. Further, in the present embodiment, the superconducting coil for magnetic flux input is arranged above the superconducting ring 11 via the insulating film, but it may be arranged not only above the superconducting ring 11 but also below the superconducting ring 11. good. Further, although these elements were manufactured by using Nb or Pb alloy, the same effect can be obtained even if the part manufactured by Pb alloy is manufactured by Nb or by using the oxide superconductor. Is obvious. Further, although the present embodiment relates to an element having two Josephson junctions, it is obvious that the same effect can be obtained also for an element having only one Josephson junction.

[0038]

As described above in detail, the superconducting quantum interference device of the present invention is provided with a superconducting coil in which a spiral portion is formed by dividing the wiring layer into two or more wiring layers made of a superconducting thin film. In comparison, the device can be made highly sensitive by downsizing the device and reducing parasitic components.

Also, in the superconducting quantum interference device of the present invention, the superconducting coil for inputting the magnetic flux which generates a magnetic field substantially in the opposite direction to the superconducting ring is electrically insulated from the superconducting ring by sandwiching the superconducting ring. By arranging in this way, it was possible to detect the difference in the magnetic flux changes detected by the superconducting coils for magnetic flux detection connected to the respective superconducting coils for magnetic flux input.

In the superconducting quantum interference device of the present invention, by disposing a plurality of superconducting coils for inputting magnetic flux having different inductances, the superconducting coil for inputting magnetic flux can be arranged according to the inductance of the superconducting coil for detecting magnetic flux. Therefore, the magnetic flux transmissibility between the superconducting coil for magnetic flux detection and the superconducting ring could be improved as compared with the conventional element.

[Brief description of drawings]

FIG. 1 is a superconducting quantum interference device of the present invention in which a superconducting coil for magnetic flux input is arranged above a superconducting ring by dividing an insulating film into two wiring layers made of a superconducting thin film to form a spiral portion. FIG. 3 is a structural schematic diagram showing a state in which a superconducting coil for magnetic flux detection is connected to the.

FIG. 2 is a superconducting quantum interference device of the present invention in which a superconducting coil for magnetic flux input is arranged above a superconducting ring by dividing an insulating film into three wiring layers made of a superconductor thin film to form a spiral portion. FIG.

FIG. 3 is a superconducting quantum interference device of the present invention in which a superconducting coil for magnetic flux input is arranged above a superconducting ring by dividing an insulating film into four wiring layers made of a superconducting thin film to form a spiral portion. FIG.

FIG. 4 is a superconducting quantum interference device of the present invention in which a superconducting coil for magnetic flux input is disposed below a superconducting ring and a spiral portion is formed by dividing the wiring layer into two wiring layers made of a superconducting thin film via an insulating film. FIG.

FIG. 5: A swirl portion is formed by dividing a superconducting ring into two wiring layers, one layer above and one layer below so as to be electrically insulated from the superconducting ring. FIG. 3 is a structural schematic view of a superconducting quantum interference device of the present invention in which a superconducting coil for magnetic flux input is arranged.

FIG. 6 shows two superconducting coils for inputting magnetic flux, which generate magnetic flux in substantially opposite directions with respect to the superconducting ring, and the superconducting ring is electrically connected above and below the superconducting ring. It is a structural schematic diagram which shows the state which connected the superconducting quantum interference element of this invention arrange | positioned so that it might be insulated, and the superconducting coil for magnetic flux detection.

FIG. 7 is a structural schematic diagram of a superconducting quantum interference device of the present invention in which a plurality of superconducting coils for inputting magnetic flux having different inductances are arranged.

FIG. 8 is a structural schematic diagram of a conventional superconducting quantum interference device.

[Explanation of symbols]

11 superconducting ring 12, 22, 32, 42, 52, 621, 622, 72
1, 722, 723, 82 Superconducting coil for inputting magnetic flux 631, 632, 83 Superconducting wiring 641, 642, 84 Superconducting coil for detecting magnetic flux 85 Josephson junction (JJ) 86 Lower electrode 87 Upper electrode 88 Superposition of slits 89 Aperture

Claims (18)

[Claims] 1. A superconducting ring having a Josephson junction, which is provided on a substrate, and a superconducting coil for magnetic flux input for magnetically coupling to the superconducting coil for magnetic flux detection. In the superconducting quantum interference device having the above, the superconducting coil for magnetic flux input is divided into a plurality of wiring layers made of a superconductor thin film and arranged. 2. The superconducting quantum interference device according to claim 1, wherein a plurality of wiring layers made of a superconducting thin film forming the superconducting coil for inputting the magnetic flux are insulated above or below the superconducting ring. A superconducting quantum interference device, which is arranged through a film. 3. The superconducting quantum interference device according to claim 1, wherein at least two layers out of a plurality of wiring layers made of a superconducting thin film forming the superconducting coil for inputting the magnetic flux have a spiral shape. A superconducting quantum interference device characterized by the above. 4. The superconducting quantum interference device according to claim 1, wherein the superconducting coil for magnetic flux input formed by at least two layers of the plurality of wiring layers made of the superconducting thin film is formed on the superconducting ring. A superconducting quantum interference device characterized in that it is arranged as if magnetic fluxes were coupled to generate a circulating current. 5. The superconducting quantum interference device according to claim 1 or 2, wherein the superconducting coil for inputting the magnetic flux is formed of at least two layers of a plurality of wiring layers made of the superconducting thin film. A superconducting quantum interference device characterized in that the superconducting quantum interference device is arranged so as to generate a magnetic flux interlinking with the opening. 6. The superconducting quantum interference device according to claim 1, wherein a plurality of wiring layers made of a superconducting thin film forming the superconducting coil for inputting the magnetic flux are divided into insulating films above and below the superconducting ring. A superconducting quantum interference device characterized in that it is arranged via 7. The superconducting quantum interference device according to claim 6, wherein at least one wiring layer is provided above and below the superconducting ring of a plurality of wiring layers made of a superconducting thin film forming the superconducting coil for inputting the magnetic flux. A superconducting quantum interference device characterized in that the layers have a spiral shape. 8. A superconducting ring having a Josephson junction provided on a substrate, and a superconducting ring sandwiched between the superconducting ring and the superconducting ring arranged so as to be electrically insulated from each other. And two superconducting coils for magnetic flux input for connecting and respectively connecting the superconducting coils for magnetic flux detection, wherein the superconducting coil for magnetic flux input is substantially connected to the superconducting ring. A superconducting quantum interference device having a structure for generating a magnetic field in substantially opposite directions. 9. The superconducting quantum interference device according to claim 8, wherein the two superconducting coils for inputting magnetic flux have substantially the same magnetic flux transmissibility with respect to the superconducting ring. Superconducting quantum interference device. 10. The superconducting quantum interference device according to claim 8 or 9, wherein the magnetic flux inputting superconducting coil is divided into a plurality of wiring layers made of a superconductor thin film. element. 11. A superconducting quantum interference device according to claim 10, wherein at least two layers out of a plurality of wiring layers made of a superconducting thin film forming the superconducting coil for inputting the magnetic flux have a spiral shape. Characteristic superconducting quantum interference device. 12. The superconducting quantum interference device according to claim 10, wherein the superconducting coil for magnetic flux input formed by at least two layers of the plurality of wiring layers made of the superconducting thin film is provided with respect to the superconducting ring. A superconducting quantum interference device characterized in that it is arranged as if magnetic fluxes combine to generate a circulating current. 13. The superconducting quantum interference device according to claim 10, wherein the superconducting coil for magnetic flux input formed by at least two layers of the plurality of wiring layers made of the superconducting thin film has an opening in the superconducting ring. A superconducting quantum interference device characterized in that the superconducting quantum interference device is arranged as if a magnetic flux interlinking with each other were generated. 14. A superconducting ring having a Josephson junction provided on a substrate, and a superconducting coil for magnetic flux input, which is magnetically coupled to the superconducting ring and is connected to a superconducting coil for magnetic flux detection. In the superconducting quantum interference device having the above, a plurality of superconducting coils for inputting the magnetic flux are arranged, each having a different inductance. 15. The superconducting quantum interference device according to claim 14, wherein the magnetic flux inputting superconducting coil is divided into a plurality of wiring layers each made of a superconductor thin film. element. 16. The superconducting quantum interference device according to claim 15, wherein at least two layers out of a plurality of wiring layers made of a superconductor thin film forming the superconducting coil for inputting the magnetic flux have a spiral shape. Characteristic superconducting quantum interference device. 17. The superconducting quantum interference device according to claim 15, wherein the magnetic flux inputting superconducting coil formed by at least two layers of the plurality of wiring layers made of the superconducting thin film is provided with respect to the superconducting ring. A superconducting quantum interference device characterized in that it is arranged as if magnetic fluxes combine to generate a circulating current. 18. The superconducting quantum interference device according to claim 15, wherein the superconducting coil for magnetic flux input formed by at least two layers of the plurality of wiring layers made of the superconducting thin film has an opening in the superconducting ring. A superconducting quantum interference device characterized in that the superconducting quantum interference device is arranged as if a magnetic flux interlinking with each other were generated.