JPH05175560A - Superconducting quantum interference element - Google Patents

Abstract

PURPOSE:To provide a superconducting quantum interference element of both high sensitivity and low noise which enables reducing damping resistance inductance without increasing parasitic capacity. CONSTITUTION:One end of a damping resistance 14 is connected to a superconducting ring 11a, and the other end is connected to an overlaping part 17 of a slit connected to a superconducting ring 11b. The damping resistance 14 is positioned above the superconducting ring 11a while being covered by the slit overlaping part. After an Nb film is deposited an Si substrate whose surface thermally oxidized, the Nb film is treated by reactive etching using a resist as a mask for forming a pattern at bath the superconducting ring and the slit overlaping part. Inter-layer insulation films 19a and 19b are formed between the superconducting ring and the damping resistance or between the resistance and the slit overlaping part. Then, after the patterns corresponding to a signal input superconducting coil 16 and an upper electrode 18 are formed, a baffle layer is formed on the electrode surface by plasma-oxidization. Further, a lead alloy is vapor-deposited by lift-off method so as to form a coil and electrode.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a superconducting quantum interference device for detecting a minute magnetic field.
ence device; SQUID), and more particularly to a superconducting quantum interference device with high sensitivity and low noise.

[0002]

2. Description of the Related Art A superconducting quantum interference device is a device capable of detecting a minute magnetic field by utilizing the property of superconductivity. For example, Japanese Journal of Applied Physics, Vol. ) L798 ~ L800 page
(Japanese Journal of Applied Physics, Vol.24 No10 (19
85) pp.L798-L800).

In a conventional magnetometer using a superconducting quantum interference device, in general, a magnetic flux is not directly detected by a superconducting ring having a Josephson junction, but an input circuit formed by a superconducting closed circuit is used. A method of detecting magnetic flux via FIG. 10 shows a part of the structure of a conventional superconducting quantum interference device body used as a part of a magnetometer. In the figure, 11a and 11b are superconducting rings (hereinafter referred to as superconducting rings) having a Josephson junction (hereinafter abbreviated as JJ), 12 is JJ, and 13 is a current-
A shunt resistor for removing the hysteresis generated in the voltage characteristic, 14 is a damping resistor for eliminating the voltage step generated in the current-voltage characteristic due to the inductance of the superconducting rings 11a and 11b and the capacitance of the superconducting quantum interference device,
15 is the lower electrode, 17 is the overlapping part of the slits provided to reduce the parasitic inductance of the superconducting rings 11a and 11b, 18 is the upper electrode, and 20 is the superconducting rings 11a and 11b.
The slit part of is shown. The illustration of the interlayer insulating layer is omitted.

In the prior art superconducting quantum interference device, the damping resistance is simply arranged between the superconductors forming the superconducting ring, or as shown in FIG.
As shown in Fig. 2, the wire was inserted between two superconductors 15 which will be the lower electrode of JJ 12, and the upper part thereof was covered with the superconductor which will be the upper electrode 18 of JJ 12.

[0005]

In the superconducting quantum interference device having the structure according to the above-mentioned prior art, when the damping resistance is simply provided between the superconductors forming the superconducting ring, it exists parasitically on the damping resistance. Inductance increases, and due to that inductance,
Since the voltage step could not be removed completely, a highly sensitive superconducting quantum interference device could not be obtained.

If the upper part of the damping resistor is covered with a superconductor serving as the upper electrode of JJ, the parasitic electrostatic capacitance existing in parallel with JJ of the superconducting quantum interference device becomes large. Therefore, in order to realize the optimum value of β _C (Maccamber coefficient) for increasing the output voltage, the superconducting quantum interference device in which the upper part of the damping resistor is not covered with the superconductor serving as the upper electrode of JJ The shunt resistance value or the critical Josephson current value of JJ must be made smaller than that of, and as a result, the output voltage of the superconducting quantum interference device becomes smaller. There was a problem that I could not. Here, β _C is a parameter representing the output of the superconducting quantum interference device and is represented by the following equation.

[0007]

[Equation 1]

Here, R is the shunt resistance, I is the critical Josephson current value of JJ, C is the capacitance of the superconducting quantum interference device, and Φ ₀ is the flux quantum. When this parameter is in the range of β _C <1, the output voltage of the superconducting quantum interference device increases as the value of β _C increases.

Further, as described above, in the prior art superconducting quantum interference device in which the upper part of the damping resistance is covered with the superconductor serving as the upper electrode of JJ, the parasitic capacitance becomes large, so that the optimum damping resistance value is obtained. Is smaller than that when the upper part of the damping resistance is not covered by the superconductor which is the upper electrode of JJ. Therefore, there is a problem that the magnetic flux noise of the superconducting quantum interference device increases, and a low-noise superconducting quantum interference device cannot be manufactured.

As described above, in the prior art, it cannot be said that sufficient consideration has been given to realize a superconducting quantum interference device with high sensitivity and low noise. An object of the present invention is to solve the problems of the above prior art and provide a superconducting quantum interference device with high sensitivity and low noise.

[0011]

The above object is a superconducting quantum interference device having at least first and second Josephson junctions and an inductance formed of a superconductor, wherein the first Josephson The junction is formed by using the first superconductor and the second superconductor as electrodes, the second Josephson junction is formed by using the third superconductor and the fourth superconductor as electrodes, and the inductance is the first Connected between the superconducting wiring provided to be connected to the superconductor of and the superconducting wiring provided to be connected to the fourth superconductor,
And, in a superconducting quantum interference device having a damping resistance connected between the superconducting wiring provided in connection with the first superconductor and the superconducting wiring provided in connection with the fourth superconductor, (1) At least a part of the damping resistance is covered by a superconductor provided connected to the first superconductor or a superconductor provided connected to the fourth superconductor, or (2) the first At least a part of the superconductor provided in connection with the superconductor or the superconductor provided in connection with the fourth superconductor, or (3) the first superconductor At least a part of the superconductor provided in connection with the body covers a part of the damping resistance, and the damping resistance covers at least a part of the superconductor provided in connection with the fourth superconductor. Or be configured to, or
(4) At least a part of the damping resistance is from the first to
It is covered by a superconductor not connected to the fourth superconductor, or (5) at least a part of the superconductors not connected to the first to fourth superconductors is covered with the damping resistor. Or (6) a superconductor which is not connected to the first to fourth superconductors covers at least a part of the damping resistance, and which is not connected to the first to fourth superconductors. At least a part of the body is configured to be covered with the damping resistance, or (7) a superconductor provided connected to the first superconductor or a fourth superconductor provided connected to the superconductor. At least a part of the superconductor is covered with the damping resistance, and at least a part of the damping resistance is covered with a superconductor not connected to the first to fourth superconductors. Or (8) at least a part of the superconductor provided in connection with the first superconductor or the superconductor provided in connection with the fourth superconductor covers the damping resistance, and, This can be achieved by using a superconducting quantum interference device having a configuration in which at least a part of the superconductor not connected to the first to fourth superconductors is covered with the damping resistor.

[0012]

By using the superconducting quantum interference device having the above-mentioned structure, the damping resistance is parasitic on the damping resistance as compared with the conventional superconducting quantum interference device in which the damping resistance is simply provided between the superconductors forming the superconducting ring. Therefore, the existing inductance can be reduced. When there is a large parasitic inductance component in the damping resistance, removal of the voltage step in the DC current-voltage characteristic of the superconducting quantum interference device is incomplete due to that effect, and the output voltage of the superconducting quantum interference device decreases, thus Although the sensitivity of the superconducting quantum interference device is reduced, in the above configuration of the present invention, since the superconductor for magnetic shielding is provided at least above or below the damping resistance,
Compared with the case where the magnetic shield superconductor is not provided, the inductance parasitically generated in the damping resistance can be reduced to about 1/5 to 1/20, so that the voltage step can be eliminated. .. Therefore, the output voltage of the superconducting quantum interference device can be increased to realize a highly sensitive superconducting quantum interference device.

Further, in the superconducting quantum interference device of the present invention, the damping resistance is parasitic on the damping resistance as compared with the conventional superconducting quantum interference device in which the damping conductor is covered with the superconductor serving as the upper electrode of JJ. When covered with a superconductor to reduce existing inductance, it does not increase parasitic capacitance. The reason for this is as follows. That is, in the conventional technique, the capacitance existing between the thin-film resistor that is the damping resistor and the superconductor that is the upper electrode of JJ above is electrically connected to the Josephson junction included in the superconducting quantum interference device. Since they are connected in parallel, this capacitance becomes the parasitic capacitance of the superconducting quantum interference device. On the other hand, in the case of the configuration of the present invention, between the superconductor and the thin film resistor which is a damping resistor provided in a part or all of the upper part or the lower part of the damping resistor for the purpose of reducing the parasitic inductance of the damping resistor. It is characterized in that the electrostatic capacity existing in is charged by an alternating voltage generated from the Josephson junction is substantially negligible.
That is, the superconducting quantum interference device is configured so that the above capacitance is not electrically connected in parallel with the Josephson junction. More specifically, the superconductor provided on a part or all of the upper or lower part of the damping resistor is not electrically connected to the damping resistor, or the upper or lower part of the damping resistor is not electrically connected. Of a superconducting conductor connected to a damping resistance and a superconductor provided in a part or all of the superconducting quantum interference device, forming two Josephson junctions, that is, one of an upper electrode and a lower electrode. It may be configured to be connected only to.

As described above, the superconducting quantum interference device is used as the device of the present invention, that is, the superconductor provided on a part or all of the upper or lower part of the damping resistor is electrically connected to the damping resistor. Two superconducting devices which have a Josephson junction included in the superconducting quantum interference device in which the superconducting conductor having a non-conducting structure or a superconductor provided in a part or all of the upper part or the lower part of the damping resistor and the superconductor connected to the damping resistor forms a Josephson junction. By configuring it to be connected to only one of the electrodes, that is, one of the upper electrode and the lower electrode, without substantially increasing the capacitance of the superconducting quantum interference device,
The parasitic inductance existing in the damping resistance can be reduced to about 1/5 to 1/20 of that of the conventional technique. The fact that it does not cause an increase in capacitance as described here works as follows. That is, when the superconducting quantum interference device according to the prior art and the value of β _C are designed to be the same, the superconducting quantum interference device of the present invention,
Since the parasitic capacitance is small, it is possible to increase the shunt resistance or the value of the critical Josephson current of JJ that constitutes the superconducting quantum interference device. This suitably acts on the operation of the superconducting quantum interference device as follows. The output voltage of the superconducting quantum interference device is proportional to the product of the shunt resistance value and the critical current value. Therefore, in the case of the configuration of the present invention, the output voltage can be increased and the sensitivity can be increased as compared with the conventional superconducting quantum interference device. Further, when the parasitic capacitance is reduced, the position where the voltage step occurs in the current-voltage characteristics of the superconducting quantum interference device is on the higher voltage side, and it can be separated from the operating region of the superconducting quantum interference device. As a result, the output voltage of the superconducting quantum interference device can be increased, and the sensitivity can be increased.

On the other hand, the optimum value of the damping resistance for eliminating the voltage step due to LC resonance is proportional to the square root of (L / C). Therefore, the smaller the capacitance, the larger the optimum value of the damping resistance. Further, the magnetic flux noise, which is one of the main noises of the superconducting quantum interference device, is proportional to 1 / √R. Here, R is a value of the damping resistance or a resistance value obtained by considering that the shunt resistance and the damping resistance are connected in parallel. Therefore, it can be seen that the present invention can reduce the noise of the superconducting quantum interference device by reducing the parasitic capacitance.

As described above, the superconducting quantum interference device according to the present invention can reduce the inductance of the damping resistance without increasing the parasitic capacitance. It is possible to realize a noise superconducting quantum interference device.

[0017]

EXAMPLES The superconducting quantum interference device of the present invention will be specifically described below with reference to examples.

[0018]

[Embodiment 1] FIG. 1 is a top view showing a part of the shape of an embodiment of the superconducting quantum interference device of the present invention, FIG. 2a is a top view showing the overall shape of the device, and FIG. 2b is an A in FIG. 1 and FIG. 2a.
-In the cross-sectional view of the portion A, one end of the damping resistor 14 is connected to the superconducting ring 11a, the other end is connected to the overlapping portion 17 of the slit connected to the superconducting ring 11b, and the damping resistor 14 of the superconducting ring 11a It is shown that the damping resistor 14 is arranged at a position located above and the overlapping portion 17 of the slits covers the damping resistor 14. 2A, the number of turns of the interlayer insulating layer and the superconducting coil for signal input is omitted.

Next, a procedure for manufacturing the above element will be described. First, the surface of the substrate is thermally oxidized silicon (Si)
Using a wafer, Niobium (N
b) After depositing the film by DC magnetron sputtering,
The superconducting rings 11a and 11b are formed by processing the Nb film by the reactive ion etching method using the photoresist as a mask material.
Pattern was formed. The superconducting rings 11a and 11b have a nearly square shape, and a ring is formed by providing a 25 μm square opening at the center and a slit 20 having a width of 5 μm and a length of about 260 μm from the center. Next, the process proceeds to the step of forming an interlayer insulating film.
A pattern was formed by a lift-off method using an iO vapor deposition film. After forming the interlayer insulating film 19a with a thickness of about 250 nm to electrically insulate the superconducting rings 11a and 11b from the damping resistor 14, etc., a MoN _X film with a thickness of about 300 nm is formed as a resistance film by the DC magnetron sputtering method. Then, the photoresist was used as a mask material and processed by a reactive ion etching method to form a pattern of a damping resistor 14 having a width of 5 μm and a length of 10 μm and a shunt resistor 13 having a width of 5 μm and a length of 10 μm. Each resistance value was about 4Ω. Next, damping resistor 14
After forming an interlayer insulating film 19b having a thickness of about 350 nm for electrically insulating the overlapping portion 17 of the slit and the like,
As a superposition 17 of the lower electrode 15 and the slit portion, a laminated film of a Nb film with a thickness of about 140 nm and a NbN film with a thickness of about 210 nm was formed by the DC magnetron sputtering method, and the reactive ion was used as a mask material with the photoresist. Patterns such as the overlapping portions 17 of the slits were formed by the etching method. The width of the overlapping portion was 15 μm. Although not shown in the figure, an interlayer insulating film having a thickness of about 400 nm provided with a window (bonding window 4 μm square) for defining the area of JJ 12 was formed. Next, after forming a photoresist pattern corresponding to the superconducting coil 16 for signal input and the upper electrode 18 having a width of 3 μm and a winding number of 40 and a width of 3 μm, Nb oxidation was performed on the lower electrode surface of the bonding window by a high frequency plasma oxidation method. A tunnel barrier layer was formed by using an object, and subsequently a lead (Pb) alloy with a thickness of about 500 nm was deposited. Further, the pattern of the superconducting coil 16 for signal input and the upper electrode 18 made of the Pb alloy thin film was formed by the lift-off method to complete the superconducting quantum interference device.

Since the superconducting quantum interference device of the present invention configured as described above has the superconducting material for magnetic shielding above and below the damping resistor, the damping resistance is higher than that of the conventional superconducting quantum interference device. It is possible to reduce the inductance existing parasitic on the. Also, because the superconducting ring and the overlapping portion of the slit are used as a superconductor for magnetically shielding the damping resistance,
Unlike the conventional superconducting quantum interference device that uses the superconductor that is the upper electrode of JJ as a superconductor for magnetically shielding the damping resistance, no parasitic capacitance is generated, or this is not the case in actual device operation. The existence of partial capacity can be ignored. Further, in the device of the present invention, compared with the conventional superconducting quantum interference device having no superconductor for magnetic shielding above or below the damping resistance, the inductance existing parasitic on the damping resistance is reduced to about 1/20. I was able to Furthermore, as compared with the prior art superconducting quantum interference device fabricated with the same size using a superconductor to be the upper electrode of JJ as a magnetic shield superconductor for reducing the inductance of the damping resistance, The electric capacity was able to reach about 50%.

Therefore, when the device of the present invention and the device of the conventional structure are designed to have the same β _C value, the device of the present invention can increase the output voltage by about 1.4 times. It was In addition, the capacitance of the device can be reduced to about 50% compared to the device with the conventional configuration, so the value of the damping resistance for optimally damping the voltage step can be increased. , About 0.85 noise
It could be doubled. As described above, in the device having the above-described configuration of the present invention, it was possible to achieve lower noise and higher sensitivity than the device having the conventional configuration.

Further, as shown in FIG.
It is clear that even when the connection positions of 14 are changed, the noise and the sensitivity can be improved as compared with the conventional device. Figure 3
1 is different from that of the embodiment shown in FIG. 1 in that there is a portion below the damping resistor 14 where there is no superconductor for magnetic shielding. Note that FIG.
In the above configuration, when the width of the overlapping portion 17 of the slits of the superconducting quantum interference device of FIG. 1 is equal to the width of the overlapping portion 17 of the slits of the superconducting quantum interference device of FIG. Therefore, there is an advantage that the length of the damping resistor 14 can be made more arbitrary.

[0023]

Second Embodiment Another embodiment of the superconducting quantum interference device of the present invention will be described with reference to FIG. FIG. 4 shows that the damping resistor 14 has one end on the superconducting ring 11a and the other end on the superconducting ring 1a.
1b is a cross-sectional view showing a part of a superconducting quantum interference device which is connected to a superposed portion 17 of a slit and a damping resistor 14 is arranged between a superconducting ring 11a and a superposed portion 17 of a slit. is there.

The manufacturing procedure of the element of this embodiment is almost the same as that of the first embodiment, but the step of forming the damping resistor is different. As the material of the damping resistor 14, it is necessary to use a material having a large electric resistivity in order to realize an appropriate damping resistance value.However, in the case of this embodiment, a CdS vapor-deposited thin film with a thickness of about 100 nm is used for damping. Used as a resistor. This CdS vapor-deposited thin film was formed by resistance heating vapor deposition in a vacuum container, and processed by a lift-off method using a photoresist pattern as a mask to form a damping resistor 14.
The electrical resistivity of the CdS vapor-deposited thin film used here was about 0.1 Ω · cm at the liquid helium temperature, and the contact area between the damping resistor and the superconducting thin film connected to it was 25 μm. As a result, the damping resistor 14 having a resistance value of about 4Ω was formed. In the case of the present embodiment, unlike the case of the first embodiment, after forming the superconducting rings 11a and 11b, the damping resistor 14 is formed without forming the interlayer insulating layer.

Also in the superconducting quantum interference device of this embodiment, as in the case of the first embodiment, low noise and high sensitivity can be achieved as compared with the device of the conventional structure. Also,
In the case of the element having the configuration of this embodiment, the number of interlayer insulating layers between the superconducting rings 11a and 11b and the overlapping portion 17 of the slits can be one, so that the manufacturing process of the element can be further simplified. ..

[0026]

[Embodiment 3] Still another embodiment of the superconducting quantum interference device of the present invention will be described with reference to FIG. FIG. 5 is a cross-sectional view showing a part of the superconducting quantum interference device in which the both ends of the damping resistor 14 are connected to the superconducting rings 11a and 11b located below the overlapping portion 17 of the slits. Also in this case, the method of manufacturing the element is almost the same as that in the case of the first embodiment. Also in this case, as in the case of Example 1, it was possible to achieve low noise and high sensitivity as compared with the element having the conventional configuration.

[0027]

Fourth Embodiment Still another embodiment of the superconducting quantum interference device of the present invention will be described with reference to FIG. FIG. 6 shows a part of a superconducting quantum interference device in which both ends of a damping resistor are connected to superconducting rings 11a and 11b existing below a superposed portion 17 of slits, and a damping resistor 14 is arranged in a slit portion 20. It is sectional drawing shown. The manufacturing procedure of the constituent element of this embodiment is almost the same as that of the first embodiment, but unlike the case of the first embodiment, in the case of the present embodiment, after forming the superconducting rings 11a and 11b, the interlayer insulating layer is formed. The damping resistor 14 was formed without forming it.

In the case of the constituent element of this embodiment, since the superconductor for magnetic shielding of the damping resistor 14 exists only above the damping resistor, the superconductor for magnetic shielding does not exist. It was possible to reduce the inductance of the damping resistor 14 to about 1/10 of that of the device. Also in this case, it was possible to achieve low noise and high sensitivity as compared with the device having the conventional configuration. In addition, the number of interlayer insulating layers between the superconducting rings 11a and 11b and the overlapping portions 17 of the slits can be one, so that the manufacturing process of the element can be simplified.

[0029]

[Embodiment 5] Still another embodiment of the superconducting quantum interference device of the present invention will be described with reference to FIG. FIG. 7 shows an overlapping portion 17 of the slits in which one end of the damping resistor 14 is connected to the superconducting ring 11a and the other end is connected to the superconducting ring 11b.
FIG. 6 is a cross-sectional view showing a part of a superconducting quantum interference device having a configuration in which the damping resistor 14 is not covered with the overlapping portion 17 of the slits, and the damping resistor 14 is arranged above the superconducting ring 11a.

The manufacturing procedure of the device having the constitution of this embodiment is the same as that of the first embodiment.
In the case of this embodiment, after forming the damping resistor 14, the slit overlapping portion 17 was formed without forming an interlayer insulating film, although it is almost the same as the above case.

Therefore, in the case of this embodiment, the number of interlayer insulating layers between the superconducting rings 11a and 11b and the overlapping portions 17 of the slits can be one, so that the manufacturing process of the element can be simplified. You can Further, in the case of the element having the structure of this example, as in the case of the element of the example 1, it was possible to achieve lower noise and higher sensitivity than the element having the conventional structure.

Further, in addition to the structure shown in FIG. 7, when an independent superconductor 21 not electrically connected to the superconducting ring is arranged above the damping resistor 14 as shown in FIG. The inductance of the resistor 14 can be further reduced. A superconductor may be newly provided as the superconductor 21, or a superconductor for signal input may be used.

[0033]

[Embodiment 6] Still another embodiment of the superconducting quantum interference device of the present invention will be described with reference to FIG. FIG. 9 shows the superconducting ring 11 where the slits do not overlap.
A part of a superconducting quantum interference device having a structure in which both ends of a damping resistor 14 are connected to a and 11b, and an independent superconductor 21 not electrically connected to the superconducting ring is arranged above it. It is sectional drawing which shows. The procedure for producing this element is almost the same as the procedure for producing the element of Example 1. Also in this case, as in the case of Example 1, it was possible to achieve low noise and high sensitivity as compared with the conventional element.

In the case of this embodiment, the damping resistance is
When an independent superconductor 21 which is not electrically connected to the superconducting ring is arranged above 14 but an independent superconductor which is not electrically connected to the superconducting ring is arranged below the damping resistor 14. Also, similarly, it is obvious that the noise and the sensitivity can be increased as compared with the superconducting quantum interference device according to the conventional technique.

In the above embodiment, an example in which a superconductor for magnetic shielding is arranged at least above or below the damping resistor is described, but the present invention is not limited to the above example. For example, even if a superconductor for magnetic shielding is arranged only in at least a part above or below the damping resistance, the inductance can be reduced depending on the ratio, and thus the object of the present invention can be achieved. What you can do is obvious.

In the above embodiments, the case where Nb, NbN and Pb alloys are used as the superconducting material has been described, but other superconducting materials such as Nb ₃ Si, Nb ₃ Sn and Nb are used.
The same effect can be obtained by fabricating a superconducting quantum interference device using an Nb intermetallic compound such as b ₃ Ge or an oxide material such as YBa ₂ Cu ₃ O _X.

[0037]

As described above, by using a superconducting quantum interference device as the device of the present invention, the problems of the prior art can be solved and the capacitance of the superconducting quantum interference device can be substantially reduced. The parasitic inductance that exists in the damping resistance without increasing the
Since it can be reduced to 1/20 to 1/20, the voltage step of the current-voltage characteristic can be completely removed, and the value of the shunt resistance or the value of the critical Josephson current of JJ can be increased. Since the output voltage can be increased and the noise can be reduced, a superconducting quantum interference device with low noise and high sensitivity can be provided.

[Brief description of drawings]

FIG. 1 is a top view showing a part of the configuration of an embodiment of a superconducting quantum interference device of the present invention.

2 is a top view showing the overall structure of the device of FIG. 1, b
Is a cross-sectional view of the A-A part of a.

FIG. 3 is a cross-sectional view showing the configuration when the connection location of the damping resistor is changed in the first embodiment.

FIG. 4 is a sectional view showing a part of the configuration of another embodiment of the superconducting quantum interference device of the present invention.

FIG. 5 is a sectional view showing a part of the configuration of still another embodiment of the superconducting quantum interference device of the present invention.

FIG. 6 is a sectional view showing a part of the configuration of still another embodiment of the superconducting quantum interference device of the present invention.

FIG. 7 is a sectional view showing a part of the configuration of still another embodiment of the superconducting quantum interference device of the present invention.

FIG. 8 is a sectional view showing a part of the configuration of still another embodiment of the superconducting quantum interference device of the present invention.

FIG. 9 is a sectional view showing a part of the configuration of still another embodiment of the superconducting quantum interference device of the present invention.

FIG. 10 is a top view showing a part of the configuration of a superconducting quantum interference device according to the prior art.

[Explanation of symbols]

11a, 11b ... Superconducting ring, 12 ... JJ, 13 ... Shunt resistor, 14 ... Damping resistor 15 ... JJ lower electrode, 16 ... Signal input superconducting coil, 17 ... Slits provided to reduce parasitic inductance of the superconducting ring , 18 ... JJ upper electrode, 19a, 19b, 19c ... interlayer insulating layer, 20 ... slit part of superconducting ring, 21 ... independent superconductor not electrically connected to superconducting ring.

Claims (15)

[Claims] 1. A superconducting quantum interference device having at least first and second Josephson junctions and an inductance constituted by a superconductor, wherein the first Josephson junction is a first superconductor. A second superconductor is formed as an electrode, the second Josephson junction is formed by using a third superconductor and a fourth superconductor as electrodes, and the inductance is provided by connecting to the first superconductor. Connected between the superconducting wiring and the superconducting wiring provided in connection with the fourth superconductor, and connected to the superconducting wiring provided in connection with the first superconductor and the fourth superconductor. In a superconducting quantum interference device having a damping resistance connected between the superconducting wirings provided as described above, at least a part of the damping resistance is a superconductor provided by being connected to the first superconductor. Superconducting quantum interference device, characterized in that covered by superconductor provided in connection with the fourth superconductor. 2. A superconducting quantum interference device having at least first and second Josephson junctions and an inductance constituted by a superconductor, wherein the first Josephson junction is a first superconductor. A second superconductor is formed as an electrode, the second Josephson junction is formed by using a third superconductor and a fourth superconductor as electrodes, and the inductance is provided by connecting to the first superconductor. Connected between the superconducting wiring and the superconducting wiring provided in connection with the fourth superconductor, and connected to the superconducting wiring provided in connection with the first superconductor and the fourth superconductor. In a superconducting quantum interference device having a damping resistance connected between the superconducting wirings provided in the superconducting wiring, the superconducting conductor connected to the first superconductor or the fourth superconducting conductor. Superconducting quantum interference device at least part of the superconductor is characterized in that it is covered with the damping resistor. 3. A superconducting quantum interference device having at least first and second Josephson junctions and an inductance composed of a superconductor, wherein the first Josephson junction is a first superconductor. A second superconductor is formed as an electrode, the second Josephson junction is formed by using a third superconductor and a fourth superconductor as electrodes, and the inductance is provided by connecting to the first superconductor. Connected between the superconducting wiring and the superconducting wiring provided in connection with the fourth superconductor, and connected to the superconducting wiring provided in connection with the first superconductor and the fourth superconductor. In a superconducting quantum interference device having a damping resistance connected between superconducting wirings provided as a part, at least a part of the superconductor connected to the first superconductor is a part of the damping resistance. Cover, and superconducting quantum interference device, characterized in that the damping resistor covers at least a portion of the superconductor provided in connection with the fourth superconductor. 4. A superconducting quantum interference device having at least first and second Josephson junctions and an inductance formed of a superconductor, wherein the first Josephson junction is a first superconductor. A second superconductor is formed as an electrode, the second Josephson junction is formed by using a third superconductor and a fourth superconductor as electrodes, and the inductance is provided by connecting to the first superconductor. Connected between the superconducting wiring and the superconducting wiring provided in connection with the fourth superconductor, and connected to the superconducting wiring provided in connection with the first superconductor and the fourth superconductor. In a superconducting quantum interference device having a damping resistance connected between the superconducting wirings provided as described above, at least a part of the damping resistance is a superconductor provided by being connected to the first superconductor. It is covered with a superconductor provided in connection with the fourth superconductor, or a superconductor provided in connection with the first superconductor or a superconductor provided in connection with the fourth superconductor. At least part of the body is covered with the damping resistance, or
At least a part of the superconductor provided in connection with the first superconductor covers a part of the damping resistance, and the damping resistance is provided with at least a superconductor provided in connection with the fourth superconductor. A superconducting quantum interference device characterized by covering a part thereof. 5. The superconductor provided in connection with the first superconductor or the superconductor provided in connection with the fourth superconductor is a superconductor constituting the inductance. Item 4. A superconducting quantum interference device according to item 4. 6. A superconductor provided by connecting to the first superconductor is a superconductor constituting the inductance,
Moreover, the superconductor provided so as to be connected to the fourth superconductor is a superconductor arranged so as to cover at least a part of a slit of the superconductor forming the inductance. Superconducting quantum interference device. 7. The damping resistance is entirely covered by a superconductor provided connected to the first superconductor or a superconductor provided connected to the fourth superconductor, or The superconductor provided in connection with the first superconductor or the superconductor provided in connection with the fourth superconductor is arranged over the entire lower part of the damping resistor, or the damping resistor is The first superconductor is entirely covered with a superconductor provided in connection with the first superconductor or the superconductor provided in connection with the fourth superconductor, and is entirely covered under the damping resistor. The superconducting quantum interference device according to any one of claims 4 to 6, wherein a superconductor provided to be connected to or a superconductor provided to be connected to the fourth superconductor is arranged. 8. The first superconductor and the fourth superconductor are lower electrodes having a Josephson junction, and the second superconductor and the third superconductor are upper electrodes having a Josephson junction. The superconducting quantum interference device according to any one of claims 4 to 7, wherein 9. A superconducting quantum interference device having at least first and second Josephson junctions and an inductance formed of a superconductor, wherein the first Josephson junction is a first superconductor. A second superconductor is formed as an electrode, the second Josephson junction is formed by using a third superconductor and a fourth superconductor as electrodes, and the inductance is provided by connecting to the first superconductor. Connected between the superconducting wiring and the superconducting wiring provided in connection with the fourth superconductor, and connected to the superconducting wiring provided in connection with the first superconductor and the fourth superconductor. In a superconducting quantum interference device having a damping resistance connected between superconducting wirings provided as a superconducting wire, at least a part of the damping resistance is not connected to the first to fourth superconductors. Or at least a part of the superconductor not connected to the first to fourth superconductors is covered with the damping resistor, or the first to fourth superconductors. A superconductor not connected to the body covers at least a part of the damping resistance, and at least a part of the superconductor not connected to the first to fourth superconductors is covered with the damping resistance. A superconducting quantum interference device characterized by the above. 10. The damping resistor is entirely covered with a superconductor not connected to the first to fourth superconductors, or the entire lower portion of the damping resistor is covered with the first to fourth superconductors. A superconductor that is not connected to the body is placed, or the damping resistance is entirely covered by the superconductors that are not connected to the first to fourth superconductors, and the damping resistance is The superconducting quantum interference device according to claim 9, wherein a superconductor not connected to the first to fourth superconductors is arranged in the entire lower portion. 11. The superconducting quantum interference device according to claim 9, wherein the superconductor not connected to the first to fourth superconductors is a part of the signal input superconductor. 12. A superconducting quantum interference device having at least first and second Josephson junctions and an inductance composed of a superconductor, wherein the first Josephson junction is a first superconductor. A second superconductor is formed as an electrode, the second Josephson junction is formed by using a third superconductor and a fourth superconductor as electrodes, and the inductance is provided by connecting to the first superconductor. Connected between the superconducting wiring and the superconducting wiring provided in connection with the fourth superconductor, and connected to the superconducting wiring provided in connection with the first superconductor and the fourth superconductor. In a superconducting quantum interference device having a damping resistance connected between the superconducting wirings provided as above, the superconducting conductor connected to the first superconductor or the fourth superconductor is connected. At least a part of the superconductor is covered with the damping resistor, and at least a part of the damping resistor is covered with a superconductor not connected to the first to fourth superconductors, or , At least a part of the superconductor provided in connection with the first superconductor or the superconductor provided in connection with the fourth superconductor covers the damping resistance, and the first to fourth A superconducting quantum interference device, wherein at least a part of a superconductor not connected to the superconductor is covered with the damping resistor. 13. The damping resistance is entirely covered by a superconductor provided connected to the first superconductor or a superconductor provided connected to the fourth superconductor, and the damping resistance is provided. Above the entire bottom of the first ~
A superconductor that is not connected to the fourth superconductor is arranged, or the damping resistance is entirely covered by the superconductor that is not connected to the first to fourth superconductors, and, 13. A superconductor provided in connection with the first superconductor or a superconductor provided in connection with the fourth superconductor is disposed on the entire lower part of the damping resistor. Superconducting quantum interference device. 14. The superconducting quantum interference device according to claim 12, wherein the superconductor not connected to the first to fourth superconductors is a part of the signal input superconductor. 15. A superconducting quantum interference device having at least first and second Josephson junctions and an inductance composed of a superconductor, wherein the first Josephson junction is a first superconductor. A second superconductor is formed as an electrode, the second Josephson junction is formed by using a third superconductor and a fourth superconductor as electrodes, and the inductance is provided by connecting to the first superconductor. Connected between the superconducting wiring and the superconducting wiring provided in connection with the fourth superconductor, and connected to the superconducting wiring provided in connection with the first superconductor and the fourth superconductor. In the superconducting quantum interference device having a damping resistance connected between the superconducting wirings provided as described above, at least a part or all of the damping resistance is covered with a superconductor, or A superconductor other than the superconductor that covers the superconductor and is connected to the second superconductor and the third superconductor without a Josephson junction. Superconducting quantum interference device.