JP2001127352A - SQUID substrate and magnetic field measuring device using the same - Google Patents

Abstract

(57) [Summary] [Object] To provide a SQUID substrate capable of releasing a magnetic flux trap. An SQUID having a Josephson junction 22 is formed on a substrate 15 and a heater 5 is formed on the substrate with a superconductor that is superconductive at the operating temperature of the SQUID. A current greater than or equal to the critical current value is passed to cause the superconductor to transition to normal conduction and generate heat, thereby releasing the SQUID magnetic flux trap. [Effect] The magnetic flux trap can be released without increasing the number of processes and manufacturing without increasing the number of processes.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for measuring a weak magnetic field in an apparatus for measuring a biomagnetic field generated from a human heart or brain, an inspection apparatus for non-destructively detecting a minute crack in a metal, and the like. Superconducting Quantum Interference Device (SQUID: Superconducting)
Quantum Interference Devi
ce), and a magnetic field measurement device using the same,
A superconducting quantum interference device that can release the trapped magnetic flux,
And a magnetic field measuring apparatus using the same.

[0002]

2. Description of the Related Art Superconducting quantum interference devices (hereinafter, SQUIDs)
) Is a highly sensitive magnetic flux-voltage conversion element,
It is used as a sensor for measuring a weak magnetic field in an apparatus for measuring a magnetic field generated from the human heart or brain, an inspection apparatus for non-destructively performing a micro-crack inside a metal, and the like. SQUI
D is Nb, YBa ₂ Cu ₃ O _7-x , Bi ₂ Sr ₂ CaCu ₂
It is generally formed on a substrate by a superconducting thin film of O ₈ , Tl ₂ Ba ₂ CaCu ₂ O ₈ or the like. The state changes from the normal conduction state to the superconducting state, and becomes operable.

[0003] When the SQUID is exposed to a magnetic field during cooling or exposed to strong magnetic noise in a cooled state, the magnetic flux may be confined while being linked to the superconducting thin film (referred to as "flux"). Called "trap"). When a magnetic flux trap is generated, the sensitivity of the magnetic flux-voltage conversion is reduced, and the trapped magnetic flux fluctuates thermally to generate noise, which is a great obstacle to measuring a weak magnetic field.

[0004] The magnetic flux trap can be released by raising the temperature of the SQUID, temporarily transitioning to normal conduction, and cooling again. However, temporarily removing the SQUID from the refrigerant is inefficient and costly as well as costly. Therefore, a method of partially heating only the SQUID in the refrigerant using a heater has been proposed. Although there is a method of installing a chip resistor near the SQUID substrate, a thinner heater can be installed closer to the SQUID and can be heated effectively.

As a prior art using a thinned heater, Japanese Patent No. 2856463 (prior art 1),
No. 78738 (Prior Art 2) and IEICE Technical Report, Vol. 91, No. 176, pp. 43-48 (Prior Art 3) are known.

In the prior art 1, the heater is composed of a plurality of thin-film resistance units, and the resistance unit is set so that the magnetic field acting on the superconducting circuit (corresponding to SQUID) becomes zero by the current flowing through the plurality of resistance units. They are in close proximity.

In the prior art 2, a Josephson junction is provided in series with a feedback coil (feedback coil) which is a component of the SQUID, and the Josephson junction is used as a heater.

The prior art 3 discloses a structure in which a resistor (molybdenum) and a superconductor (Nb), which is a wiring layer having no resistance, form a two-layer film with an insulator interposed therebetween.

In prior art 2 and prior art 3, the SQUID
And the heater are formed in a thin film on the same substrate.
Heating can be performed more efficiently than forming D and the heater on separate substrates.

[0010]

If the heater for heating the SQUID is formed on the same substrate as the SQUID, the best heating efficiency can be obtained. In addition, considering the ease of production,
It is desirable to be able to form in ID formation process. Furthermore, the heater formed on the substrate is connected to the power supply of the heater installed at room temperature by a power supply line. However, if the resistance of the heater is not sufficiently large compared to the resistance of the power supply line, the power supply power is consumed by the power supply line. It is inefficient. In many cases, the power supply line is formed of a thin wire such as manganin and has a resistance of about 10 Ω. Therefore, the resistance value of the heater needs to be, for example, about 100Ω.

When the heater is on the same substrate as the SQUID,
When formed near the UID, a wiring formed of a thin film in the substrate and a magnetic field generated by the heater itself become a problem in order to connect the heater to the power supply line, and wiring in the heater and the substrate (in the following description, When a wiring formed of a thin film in a substrate is simply called a "wiring", a magnetic field is generated, which causes a problem that a magnetic flux is trapped.

In a biomagnetic field measuring device such as a magnetocardiographic measuring device for measuring a magnetic field generated from the human heart or a magnetoencephalographic measuring device for measuring a magnetic field generated from the brain, several tens to several hundreds of SQUIDs are used. Will be installed. If all of the heaters installed integrally with the SQUID are connected to a power supply at room temperature, the number of power supply lines becomes enormous, and there is a problem that heat flows from the room temperature to the refrigerant. Also,
If a power supply for the heater is provided separately from the power supply for the drive circuit for driving the SQUID, there is a problem that the system configuration becomes complicated.

An object of the present invention is to provide an SQUID substrate which can be formed on the same substrate as the SQUID in the SQUID forming step and has a heater with a resistance value of about 100Ω, by appropriately combining the heater and wiring in the substrate. ,
An object of the present invention is to provide a heater module having a structure that does not generate a magnetic field, and to provide a magnetic field measuring device that has a small number of power supply lines for a heater and can share a power supply for a heater and a power supply for a driving circuit for driving a SQUID.

[0014]

[MEANS FOR SOLVING THE PROBLEMS] Representative SKU of the present invention
On the ID substrate, a SQUID having a Josephson junction is formed on the substrate, and a heater is formed on the same substrate with a superconductor that becomes superconducting at the operating temperature of the SQUID. A current is applied to cause the superconductor to transition to normal conduction and generate heat, thereby releasing the SQUID flux trap. The superconductor forming the heater is formed of the same material as the superconductor forming the SQUID, and the normal conductor forming the wiring is formed of the same material as the normal conductor forming the SQUID. A heater module having a two-layer structure including a heater and a wiring formed via an insulating layer can be easily formed on a substrate on which a SQUID is formed by utilizing a manufacturing process.

In the SQUID board of the present invention, the SQUID
On the same substrate as above, a heater is formed from a superconducting thin film forming a SQUID. The thickness of the thin film is usually 1 μm or less.
The heater is composed of a superconducting thin film wire having a width of 5 μm or less, and a power supply is connected to the heater to flow a current equal to or greater than the critical current value. If the superconductor of the SQUID is, for example, Nb, the resistance when Nb is transferred to the normal conductor is SQUID.
As compared with other metal materials used for D, for example, Al and Au, a heater having a large resistance value can be realized. SQ
Since the manufacturing process of the UID includes the film formation and processing of the superconducting thin film without exception, if the heater is manufactured using the SQUID manufacturing process, a high-resistance heater can be realized without increasing the number of processes.

Prior Art 3 discloses a configuration in which a current equal to or more than a critical current value is passed through a Josephson junction and used as a heater. Compared to using a point like a Josephson junction (more precisely, a weakly-bonded portion such as an oxide layer sandwiched between superconductors) as a heater, the structure of the present invention in which the superconducting thin film itself is used as a resistor is used. There is an advantage that a larger resistance value can be easily realized.

In a heater module in which a heater made of a superconducting thin wire and a normal conductor wiring form a two-layer structure with an insulating layer interposed therebetween, currents of opposite magnitudes flow through the heater and the normal conductor wiring. As described above, the wires of the heater and the normal conductor are connected to the power supply. In order to provide a simple configuration, at least one contact hole is provided in the insulating layer so that the heater and the wiring form an electrically serial parallel reciprocating conductor.
When the heater and the wiring are connected to a power source, currents of opposite magnitudes and the same flow through the heater and the wiring. The necessary heat is generated from the heater portion, which is a superconducting thin film wire.
Wiring need not contribute to heat generation. Therefore, it is not necessary to use a high-resistance material for the wiring, and the wiring may be made of a suitable metal material used for the SQUID, for example, Al or Au. Rather, it is better to make the wiring line width wider than the heater line width so that the heater does not melt due to heat generation.

The feature of the configuration of the present invention is that the superconducting thin film is used not as a wiring but as a heater, as in the prior art 3.
Unlike the first conventional example, one of the two-layer structures is a wiring that does not contribute to heat generation. According to a feature of the configuration of the present invention, the wiring of the normal conductor only needs to be metal, and
It is not necessary to be limited to high resistance materials such as. SQUI
Since the step of forming D includes the steps of forming and processing a normal metal without exception, a heater module that does not generate a magnetic field can be formed in the step of forming a SQUID.

If the heater and the wiring have a two-layer structure, the individual structures of the heater portion and the wiring portion are arbitrary, and it is not necessary to use a structure that generates less magnetic field. The shape may be circular or linear, but it is practical if the heater module is appropriately folded so as not to occupy an unnecessary area.

A typical magnetic field measuring apparatus of the present invention uses a plurality of SQUID substrates on which a SQUID is formed on a substrate and a heater for transferring the SQUID to normal conduction when an electric current is applied to the same substrate. Then, two or more of the heaters of the plurality of SQUID substrates are electrically connected in series or in parallel, and two or more heaters connected in series or in parallel are connected to a power supply through a set of wirings, The SQUID is driven by the same power supply, and the superconductor constituting the heater is:
Made of the same material as the superconductor that constitutes the SQUID,
The normal conductor forming the wiring is made of the same material as the normal conductor forming the SQUID. The superconductor and the wiring constituting the heater are in electrical contact with each other in at least one place so as to be electrically connected in series when connected to the power supply. Are equal to each other and a current equal to or greater than the critical current value of the superconductor flows, and SQ
The magnetic flux trap of the UID can be released.

Since the heaters of the plurality of SQUID substrates are electrically connected in series or in parallel with each other and connected to a power source,
Multiple SQUIDs can be heated simultaneously. If necessary,
All the SQUIDs may be divided into a plurality of groups, and the heaters of the SQUIDs in each group may be connected in series or in parallel to energize simultaneously. At this time, the number of power supplies and power supply lines of the heater only needs to be equal to the number of groups, and the number of power supplies and power supply lines of the heater can be greatly reduced.

Further, since the resistance value of each heater is determined by the line width and length of the superconducting thin film, the resistance value of each heater can be appropriately set, and the power supply voltage of the heater is reduced by the power supply of the drive circuit for driving the SQUID. , Sufficient electric power can be supplied to each heater. Details such as specific power supply voltage values and resistance values will be described later. By heating the heaters of a plurality of SQUID substrates with a single power supply and sharing the power supply of the heater with the power supply of a drive circuit for driving the SQUID, the magnetic field measuring device has a simple configuration and less heat flow into the refrigerant. Can be realized.

[0023]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to the drawings. In addition, in order to prevent the figure from being complicated, parts other than those to be described in the figure are omitted as appropriate.

FIG. 1 is a view for explaining an example of a heater module according to an embodiment of the present invention. FIG. 1 is a top view showing a heater module formed of a thin film on a substrate and its peripheral portion. 2A and 2B are cross-sectional views of the heater module. FIG. 2A is a cross-sectional view of AA ′ (pad portion) shown in FIG. 1, and FIG. 2B is a cross-sectional view of B-B shown in FIG.
FIG. 2C is a cross-sectional view at B ′ (connection part).
FIG. 5 is a cross-sectional view of CC ′ (a heater module part) shown in FIG.

As shown in FIG. 2, the insulating layer 13 is sandwiched between
A resistance layer 12 is formed as a lower layer, and an Nb layer (superconducting layer) 11 is formed as an upper layer. However, the resistance layer 12 and the superconducting layer 11 are in electrical contact with each other at the contact hole 3 shown in FIG. As shown in FIG. 1, in the heater module 5, the superconducting layer and the resistance layer each having a narrow line width have a bent portion. The superconductive layer 11 forms the heater 1, and the resistance layer 12 forms the wiring 2. If a power supply is connected to the pads 4 and 4 ', the heater 1 and the wiring 2 form a series circuit connected by the contact hole 3, and form a parallel reciprocating conductor. Therefore, the heater 1 and the wiring 2
, A current having the same magnitude and the opposite direction flows, and the magnetic field generated by the heater module 5 as a whole is negligibly small.

In the following, specific explanations will be given using numerical values.
The configuration of the present invention is not limited to this numerical value. In the heater module 5, the heater 1 is a superconducting thin film of Nb having a thickness of 250 nm, a width of 3 μm, and a length of 600 mm.
μm. When a current greater than the critical current value is passed through the heater 1, the heater portion has a resistance of about 100Ω. The wiring 2 is a thin film of Al having a thickness of 100 nm, a width of 8 μm, and a length of 6
00 μm. The resistance value of the wiring portion is 10Ω or less, which is smaller by one digit or more than the resistance value of the heater portion. Since the current values flowing through the heater 1 and the wiring 2 are equal, the amount of heat generated between the heater and the wiring also has a difference of one digit or more, and the heat is solely generated by the heater. As shown in FIGS. 2B and 2C, the connection between the heater module 5 and the pads 4, 4 'is made of Nb and Al, similarly to the heater module 5.
Although it is a layer film, the line width of Nb and Al between the heater module 5 and the pads 4, 4 'is arbitrary as long as it is wider than the line width of the heater module portion.

In the above description, the metal-based superconducting material Nb is used as the superconducting thin film material.
Is composed of YBa ₂ Cu ₃ O _7-x , Bi ₂ S
In the case of an oxide-based superconducting thin film such as r ₂ CaCu ₂ O ₈ or Tl ₂ Ba ₂ CaCu ₂ O ₈ , these oxide-based superconducting thin films are processed into a thin line shape, and a metal-based superconducting material is formed. The heater module can be configured in the same manner as when used.

That is, the superconductor is a superconductor having a width of 5 μm or less and / or a thickness of 1 μm or less and containing any one of niobium, a niobium compound, yttrium, bismuth, and thallium (a metal-based superconducting thin film or an oxide). (Superconductor thin film).

(Structure of SQUID Substrate) FIG. 3 shows an SQUID board according to an embodiment of the present invention on which a SQUID and a heater module are mounted.
FIG. 4 is a top view of the QUID substrate, and FIG. 4 is a view schematically showing a cross section of the SQUID substrate. As shown in FIG.
D and the layer 16 on which the heater module is formed are formed on the silicon substrate 15 via the insulating layer 14.

As shown in FIG. 3, the SQUID portion has a known structure, and includes a washer ring 21, a Josephson junction 22, an input coil 23, and a feedback coil 24. FIG.
Include electrode pads 6 and 7 for supplying a bias current to the SQUID, electrode pads 6 ′ for measuring an output voltage,
7 ', pads 8 and 8' for connecting the input coil 23 and the detection coil, and pads 9 and 9 'for connecting the feedback coil 24 and a drive circuit for driving the SQUID.

FIG. 5 is a diagram for explaining the relationship between the superconducting layer and the resistance layer, and is a perspective view showing the structure of the SQUID substrate according to the embodiment of the present invention for each layer. Actually, the SQUID is formed of a larger number of layers, but is omitted as appropriate in FIG. The SQUID washer 21 and the Josephson junction 22 are formed of the superconducting layer 10. Superconducting layer 1
There is a resistance layer 12 on 0, and the wiring 2 of the heater module 5 is formed. Although not shown in FIG. 5 because of its small size,
A resistance in the SQUID called a shunt resistance or a damping resistance is also formed by the resistance layer 12. On the resistance layer 12,
There is another superconducting layer 11 and the SQUID input coil 23
The heater 1 is formed together with the feedback coil 24. There is an insulating layer (not shown in FIG. 5) between the layers, and a contact hole is opened at a necessary portion. As is clear from the configuration in FIG. 5, the heater module 5 can be easily formed without increasing the number of manufacturing steps of the SQUID.

As shown in FIG. 3, the heater module 5 is arranged near the Josephson junction 22 for the following two reasons. The first reason is to efficiently heat the Josephson junction where the influence of the magnetic flux trap is most significant. The magnetic flux may be trapped anywhere in the superconducting thin film, but the most important obstacle in practical use is the SQ
It is a trap to a Josephson junction that reduces the sensitivity of the UID to magnetic flux-to-voltage conversion. The second reason is that a temperature gradient is generated when the washer portion is recooled. It is well known in the prior art 1, the prior art 3 and the like that when the SQUID is heated to release the trap, it is particularly effective to cool the SQUID so as to have a temperature gradient during recooling.

FIG. 6 is a graph showing measured values showing the relationship between the heating power and the resistance between terminals of the SQUID when the SQUID is heated using the heater module on the SQUID substrate having the structure shown in FIG. The result shown in FIG. 6 is obtained by applying a constant bias current using the electrode pads 6 and 7 of the SQUID shown in FIG. 3 and measuring the voltage between the electrode pads 6 ′ and 7 ′ for measuring the output voltage. The result is obtained by applying a current to the heater module 5 to heat the SQUID. When the SQUID is heated and the temperature rises, and the superconductivity is lost, the sensitivity is lost and the inter-terminal resistance is increased. Therefore, from the result shown in FIG. 6, the power required to eliminate the superconductivity of the SQUID is reduced. Desired. From FIG. 6, the heating power at which the loss of sensitivity and the increase in the resistance between the terminals of the SQUID are 230 mW or more,
It can be seen that when a heating power of 30 mW is applied, the superconductivity of the SQUID disappears and the magnetic flux trap can be released.

(Mounting of SQUID Board) FIG. 7 is a perspective view showing a configuration example of the SQUID magnetometer 50 according to the embodiment of the present invention. The SQUID substrate 20 on which the heater module 5 is formed is connected to the detection coil 31. Detection coil 3
1 cuts a groove in a resin bobbin 40 having a diameter of 18 mm,
An Nb-Ti wire is wound in the groove. SQ shown in FIG.
The configuration of the UID magnetometer 50 is a configuration of a so-called gradiometer that measures a differential magnetic field in a space in order to remove an environmental noise magnetic field, in which a sensing coil 31a and a cancellation coil 31b are wound in opposite directions. . The SQUID board 20 is bonded to a mounting board 33 having a connector 34, and each pad of the SQUID board 20 is connected to an electrode of the mounting board 33 by wire bonding.

The pads 8, 8 'shown in FIG. 3 for connecting the input coil 23 and the detection coil 31 are formed of Pb-In-Au.
Is superconductively connected to the superconducting wire 17 of the detection coil 31 via the superconducting bonding wire of No. 7, and the pads other than the pads 8 and 8 'are connected to the connector 34 via the Al bonding wire and the electrode of the mounting board 33. You. Since the heater module 5 is formed on the SQUID substrate 20, it is only necessary to bond the SQUID substrate 20 to the mounting substrate 33, and the SQUID magnetometer 50 can be manufactured with a simple configuration with a small number of components.

(Arrangement of SQUID magnetometer and wiring of heater) FIG. 8 shows an arrangement example of the SQUID magnetometer 50 shown in FIG. 7 and an example of wiring to the heater, which are arranged at the bottom of the low-temperature container of the magnetocardiograph. FIG. In the magnetocardiograph,
The arrangement of the SQUID magnetometer is planar, for example, 8
It is arranged in the form of a matrix of 8 pieces and is placed at the bottom of a cryogenic vessel filled with a refrigerant to form an array (sensor array) of SQUID magnetometers. 64 SQUIDs in total
The magnetometers are divided into groups of eight, and the heaters in each group are wired so as to be electrically parallel to each other. FIG. 8 shows only one group of wires.

As shown in FIG. 8, the eight heaters are connected to a room temperature power supply 100 through a pair of power supply lines 18. The material of the power supply line 18 connecting between the room temperature and the refrigerant needs to be a metal with low heat conductivity, and in the example shown in FIG.
Manganin wire is used. The manganin wire has a large electric resistance and is about 15Ω at a length of 1 m. Therefore, if the resistance of each heater is small, most of the power is consumed by the manganin wire on the way, and the heat generation of the heater becomes insufficient. However, if the heater module having the configuration shown in FIG. 1 is used, since each heater has a resistance of 100Ω, the power supply (12 V power supply) of the drive circuit for driving the SQUID is used as the power supply.
, The current flowing through each heater is 55 mA,
The heat value of each heater is 300 mW. As shown in FIG. 6, the SQUID is sufficiently heated by the heating power of 300 mW, and the magnetic flux trap can be released.

Although not shown, similar effects can be expected even if the heaters in the group are electrically connected in series. In this case, the number of SQUID magnetometers in one group is 16, and the resistance value of each heater is 80Ω.
So that Specifically, in the heater module shown in FIG. 1, the thickness and the line width of the thin film of the heater and the wiring may be the same, and only the length may be 480 μm. The power supply voltage of the heater is set to 100 V, which is the same as the commercial power supply voltage. In this case, the current flowing through each heater is 55 mA, and the heating power of each heater is 240 mW. As shown in FIG. 6, the magnetic flux trap can be released even with the heat generation of 240 mW.

In the example described above, even if one SQUID is trapped in a magnetic flux, eight or sixteen SQUIDs can be used.
The ID will be heated, but there is no practical problem. Further, it is practical to control the opening and closing of the switch 19 for heating by a control computer.

(Magnetocardiographic measuring device, magnetoencephalographic measuring device) FIG.
1 is a diagram illustrating a configuration example of a magnetocardiographic measurement device as an example of a magnetic field measurement device using a SQUID magnetometer according to an embodiment of the present invention. The array (sensor array) of the SQUID magnetometer 50 shown in FIG.
It is installed at the bottom. The cryogenic container 200 is installed in the magnetic shield room 160 and the magnetic shield room 1
The inside of 60 is monitored by a camera 150. Outside the magnetic shield room 160, a drive circuit 110 for driving the SQUID, a control and data collection computer (signal collection means) 130, and an analysis computer 140 are provided. An electrocardiograph 120 is also installed, and electrocardiographic data is collected by the control and data collection computer 130 together with cardiac magnetic field measurement data. The power supply 100 that supplies power to the heater module is 12 V shared with the power supply of the drive circuit that drives the SQUID. Power supply 100
Thus, eight sets of 16 power supply lines 18 extend to the sensor array, and each power supply line shunts near the sensor array and supplies power to eight heater modules connected in parallel. The control and data collection computer 130 controls the supply of power to the heater module for each sensor group.

FIG. 10 is a diagram showing an example of the configuration of a magnetoencephalograph as an example of a magnetic field measuring apparatus using the SQUID magnetometer according to the embodiment of the present invention.

In the magnetoencephalograph, an array (sensor array) of SQUID magnetometers 50 shown in FIG. 8 is arranged in a spherical shape according to the shape of the skull. The number of SQUID magnetometers 50 is also large, and 128 are provided. Also, an electroencephalograph 170 is installed instead of the electrocardiograph shown in FIG. Although it is necessary to apply a stimulus to a subject in the brain magnetic field measurement, a small speaker 190 and an acoustic device 180 for auditory stimulation are illustrated here. The other configuration is the same as that of the magnetocardiographic measuring device shown in FIG. 9. From a power supply 100 for supplying power to the heater module, 16 sets of 32 power supply lines 18 extend to a sensor array, and each power supply line is connected to a sensor array. Electric power is supplied to eight heater modules connected in parallel and shunted near the array.

In the magnetocardiographic measuring device and the magnetoencephalographic measuring device described above, it is not necessary to newly provide a power supply for supplying electric power to the heater module, and the magnetic flux trap of the SQUID can be canceled with a simple configuration. It is. Further, the number of power supply lines is only 1/8 of the case where electric power is supplied to each SQUID magnetometer, and the amount of heat evaporation of the refrigerant is suppressed.

[0044]

According to the present invention, a SQUID capable of releasing a magnetic flux trap without increasing the number of manufacturing steps and a SQUID magnetometer using the same can be realized.
Using the magnetometer, it is possible to realize a magnetic field measuring device capable of releasing the magnetic flux trap without increasing a new power supply.

[Brief description of the drawings]

FIG. 1 is a top view showing an example of a heater module according to an embodiment of the present invention and a peripheral portion thereof.

FIG. 2 is a cross-sectional view of the heater module according to the embodiment of the present invention, in which (a) is a cross-sectional view along AA ′ shown in FIG. 1;
FIG. 2B is a cross-sectional view taken along the line BB ′ shown in FIG. 1, and FIG. 2C is a cross-sectional view taken along the line CC ′ shown in FIG.

FIG. 3 is a top view of the SQUID board on which the SQUID and the heater module according to the embodiment of the present invention are mounted.

FIG. 4 is a view schematically showing a cross section of a SQUID substrate according to the embodiment of the present invention.

FIG. 5 is a perspective view showing the configuration of the SQUID substrate according to the embodiment of the present invention for each layer.

FIG. 6 is a view showing measured values showing a relationship between heating power and resistance between terminals of the SQUID when the SQUID is heated using a heater module on the SQUID substrate having the configuration shown in FIG. 3;

FIG. 7 is a perspective view showing a configuration example of a SQUID magnetometer according to the embodiment of the present invention.

FIG. 8 is a diagram illustrating an example of an arrangement of SQUID magnetometers arranged at the bottom of the low-temperature container and an example of wiring to heaters in the magnetocardiograph using the SQUID magnetometer of FIG. 7;

FIG. 9 is a diagram showing a configuration example of a magnetocardiograph according to an embodiment of the present invention.

FIG. 10 is a diagram illustrating a configuration example of a magnetoencephalograph according to an embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Heater, 2 ... Wiring, 3 ... Contact hole, 4, 4
... Electrode pad for heater module, 5 ... Header module, 6,6 ... Electrode pad for SQUID, 7,7 ... SQUA
ID electrode pad, 8, 8 ... input coil pad, 9,
9: feedback coil pad, 10: superconducting layer, 11: superconducting layer, 12: resistive layer, 13: insulating layer, 14: insulating layer, 1
5: Silicon substrate, 16: Layer on which SQUID and heater module are formed, 17: Superconducting wire, 18: Power supply line, 19: Switch, 20: SQUID substrate, 2
1: Washer, 22: Josephson junction, 23:
Input coil, 24: feedback coil, 31: detection coil, 3
1a: sensing coil, 31b: cancellation coil, 33: mounting board, 34: connector, 40: bobbin, 50: sensor, 100: power supply of heater and drive circuit, 110: drive circuit, 120: electrocardiograph, 130 ... Computer for control and data collection, 140: Computer for analysis, 150: Monitor camera, 160: Shield room, 170: EEG, 180: Sound device, 190: Speaker, 200: Cryogenic container.

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[Procedure amendment]

[Submission date] August 9, 2000 (200.8.9)

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Claims

[Correction method] Change

[Correction contents]

[Claims]

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H01L 39/24 ZAA H01L 39/24 ZAAZ (72) Inventor Daisuke Suzuki 1-280, Higashi Koikebo, Kokubunji-shi, Tokyo Stock Central Research Laboratory, Hitachi, Ltd. (72) Inventor Seiichi Ukai 882, Ma, Hitachinaka-shi, Ibaraki Prefecture F-term in the Hitachi Measuring Instruments Group (reference) 2G017 AA04 AC04 AD06 AD32 AD33 AD36 AD40 4C027 AA02 AA10 EE01 KK01 KK07 4M113 AC08 AC33 AD04 AD34 AD36 AD44 AD51 AD56 CA13 CA17 CA34 CA35 CA36 4M114 AA13 AA19 AA27 BB03 CC08 CC16

Claims (20)

[Claims] 1. A substrate on which a SQUID having a Josephson junction is formed, and a heater formed on the substrate with a superconductor that becomes superconductive at an operating temperature of the SQUID, wherein the heater includes A SQUID substrate, wherein a current higher than the critical current value of the superconductor is passed to cause the superconductor to transition to normal conduction and generate heat, thereby canceling the magnetic flux trap of the SQUID. 2. The SQUID substrate according to claim 1, wherein the superconductor has a width of 5 μm or less and / or a thickness of 1 μm.
m, niobium, a niobium compound, yttrium,
A SQUID substrate formed of a thin film of a superconductor containing either bismuth or thallium. 3. The SQUID according to claim 1 or claim 2.
In the substrate, a wiring composed of a normal conductor is provided via the superconductor and the insulator, and currents of the same magnitude are applied to the superconductor and the wiring in opposite directions to each other. SQUID substrate. 4. The SQUID according to claim 1 or claim 2.
The substrate has a wiring composed of a normal conductor via the superconductor and the insulator, and the superconductor and the wiring are connected at least at one position so as to be electrically in series when connected to a power supply. Characterized by being in electrical contact with each other
ID board. 5. The SQUID according to claim 3 or claim 4.
A SQUID substrate, wherein a width of the wiring is wider than a line width of the superconductor. 6. The S according to claim 3, wherein
In the QUID substrate, the superconductor forming the heater is formed of the same material as the superconductor forming the SQUID, and the normal conductor forming the wiring is formed of the normal conductor forming the SQUID. A SQUID substrate comprising the same material as the body. 7. A SQUID having a substrate on which a SQUID is formed, and a heater formed on the substrate and for transferring at least a portion of the SQUID to normal conduction when a current is applied.
A plurality of ID boards and two or more of the heaters of the plurality of SQUID boards are electrically connected in series or parallel, and two or more heaters connected in series or parallel form one set of wires. A magnetic field measurement device, comprising: a power source connected via the power supply. 8. The magnetic field measuring apparatus according to claim 7,
The magnetic field measuring device, wherein the SQUID is driven by the power supply. 9. The magnetic field measuring apparatus according to claim 7, wherein
A magnetic field measuring apparatus, wherein a voltage of the power supply is the same as a power supply voltage of a drive circuit for driving the SQUID. 10. The magnetic field measuring apparatus according to claim 7, wherein the voltage of the power supply is the same as a commercial power supply voltage. 11. The magnetic field measuring apparatus according to claim 7, wherein the heater is made of a superconductor that becomes superconducting at the operating temperature of the SQUID, and the superconductor has a width of 5 μm or less. And / or niobium having a thickness of 1 μm or less,
A magnetic field measuring device comprising a superconducting thin film containing any one of a niobium compound, yttrium, bismuth and thallium. 12. The magnetic field measuring apparatus according to claim 11, further comprising a wiring composed of a normal conductor via said superconductor and an insulator, wherein said superconductor and said wiring are opposite to each other. A magnetic field measuring apparatus characterized in that currents having the same magnitude in directions are passed. 13. A magnetic field measuring apparatus according to claim 11, further comprising a wiring composed of a normal conductor via said superconductor and an insulator, wherein said superconductor and said wiring are connected to said power source. A magnetic field measuring device, wherein the magnetic field measuring device is in electrical contact with at least one location so as to be electrically in series when connected to the device. 14. The magnetic field measuring apparatus according to claim 12, wherein a width of said wiring is wider than a line width of said superconductor. 15. The magnetic field measuring apparatus according to claim 12, wherein the superconductor forming the heater is made of the same material as the superconductor forming the SQUID. , The normal conductor constituting the wiring,
A magnetic field measuring device comprising the same material as a normal conductor constituting the SQUID. 16. A substrate on which a SQUID having a Josephson junction is formed, a heater formed on the substrate with a superconductor that becomes superconducting at the operating temperature of the SQUID, and the superconductor and an insulator. A plurality of SQUID magnetometers comprising a SQUID substrate having a wiring composed of a normal conductor through the SQUID magnetometer for detecting a magnetic field generated from the inspection object,
A cryogenic vessel for cooling the SQUID magnetometer;
It has a drive circuit for driving a UID magnetometer, and a power supply connected to the drive circuit and the heater, and the superconductor forming the heater is formed of the same material as the superconductor forming the SQUID. The normal conductor forming the wiring is made of the same material as the normal conductor forming the SQUID, and the superconductor and the wiring forming the heater are electrically connected when connected to the power supply. Electrical contact is made in at least one place so as to be in series, the superconductor and the wiring constituting the heater are equal in size in opposite directions to each other, and a current equal to or more than the critical current value of the superconductor is applied. A magnetic field measuring device, wherein the magnetic flux is released and the magnetic flux trap of the SQUID is released. 17. The magnetic field measuring apparatus according to claim 16, wherein the superconductor has a width of 5 μm or less and / or a thickness of 1 μm.
m, niobium, a niobium compound, yttrium,
A magnetic field measuring device comprising a thin film of a superconductor containing any of bismuth and thallium. 18. The magnetic field measuring apparatus according to claim 17, wherein a width of the wiring is wider than a line width of the superconductor constituting the heater. . 19. A magnetic field measuring apparatus according to claim 16, wherein said SQUID is driven by said power supply. 20. The magnetic field measuring apparatus according to claim 16, wherein the voltage of the power supply is the same as a commercial power supply voltage.