JPH07283445A - Superconductive connecting wire - Google Patents

Abstract

PURPOSE:To connect the outer wiring of superconductive circuit chip used for superconductive electronics in the superconductive state by burying fine wires comprising superconductive fine particles of oxides. CONSTITUTION:Through holes in diameter of 0.2mm are made in Au wires in diameter of 5mm in almost the same intervals. Next, these through holes are filled up with previously formed Y-Ba-Cu oxide particles. Next, such a compound materials are wire-drawn to squeeze the diameter of the compound lines. By repeating the wire-drawing step to reduce the wire diameter down to 0.5mm. Furthermore, these compound lines are repeatedly rolled until the sectional area is reduced down to 1/10 and the thickness not exceeding 30 micron. Through these procedures, the wire 1 comprising fine particles of Y-Ba- Cu oxide are buried in the space between the Au base material to manufacture the title superconductive wire comprising super conductive fine wire in thickness and the intervals between the fine lines not exceeding 1 micron. In the title superconductive wire, the superconductive current running therein in the connecting step can be hardly reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to superconducting electronics that exhibits unique performance by using superconductivity such as measurement of minute magnetic field, voltage standard, microwave or millimeter wave detection circuit, high-speed digital circuit, analog data processing circuit. The present invention relates to a superconducting connection wire between chips that form these devices, or between a chip and a superconducting wire such as a superconducting coil.

[0002]

External wiring of superconducting circuit chips used in conventional superconducting electronics, that is, between superconducting circuit chips and superconducting circuit chips, or between superconducting circuit chips and chip packages or substrates, or between superconducting circuit chips and semiconductor circuit chips. The method described below was used for wiring connection. That is, the superconducting circuit chip or the semiconductor circuit chip is mounted on the chip package or the substrate, and the circuit chip and the package or the substrate are separated by A
It is connected by a wire of 1 or Au. Between the superconducting circuit chip or the semiconductor circuit chip and the chip package or the substrate, an electrical connection has been obtained by ultrasonically bonding a metal thin wire such as Al or Au. Further, regarding the connection between the SQUID element and the magnetic field detection coil used for measuring the minute magnetic field, the superconducting connection was made by using a metal-based superconducting material such as Pb alloy for the magnetic field detection coil.

[0003]

The conventional connection technology for the superconducting circuit chip has the following problems.
A superconducting circuit having a superconducting element such as a Josephson junction element and a superconducting wire and having a function of data processing has an extremely high-speed arithmetic performance of gigahertz or higher.
However, in the conventional wiring connection technology, the circuit chip is a superconducting circuit, and although the signal is propagated in the chip at a high speed and with almost no distortion, the signal is taken out from the chip at the same time as the signal. Is transmitted through a normal conducting wire having a propagation loss characteristic, the signal waveform is attenuated,
The waveform is distorted. Attenuation and distortion of the signal waveform become more remarkable as the signal frequency becomes higher.

In order to prevent such signal waveform attenuation and distortion, a package or substrate is provided between the superconducting circuit chips or between the superconducting circuit chips and the semiconductor circuit chip.
It is desirable to connect with superconducting wires. In particular, an oxide superconducting wire capable of operating in liquid nitrogen is particularly desirable.

On the other hand, regarding the connection between the SQUID element and the magnetic field detection coil used for measuring a minute magnetic field, it is necessary to close the input coil connected to the magnetic field detection coil and the SQUID element with a superconducting loop. Due to the Meissner effect on the superconducting loop, the magnetic field signal detected by the magnetic field detection coil is transmitted to the input coil. Conventionally, a superconducting connection with the input coil has been made by using a metallic superconducting material such as Pb alloy for the magnetic field detecting coil. However,
The superconducting connection of an oxide coil capable of operating in liquid nitrogen is impossible with the conventional technique, and the input coil cannot be arranged on the same substrate as the SQUID element. The input coil and the magnetic field detection coil system are formed separately from the substrate of the SQUID element. In such a structure, the magnetic field coupling efficiency between the input coil and the SQUID element is low, so the magnetic field detection sensitivity is lowered.

An object of the present invention is to provide external wiring of a superconducting circuit chip used in superconducting electronics, that is, between a superconducting circuit chip and a superconducting circuit chip, between a superconducting circuit chip and a chip package or a substrate, or between a superconducting circuit chip and a semiconductor circuit chip. It is to provide a structure and a manufacturing method of a wire for superconducting connection used for wiring connection between the like.

[0007]

In order to achieve the above object, the superconducting connecting wire of the present invention has a structure in which fine wires made of a plurality of oxide superconducting fine particles are embedded in a metal.

In such a superconducting connecting wire,
The average distance between the fine wires made of oxide fine particles constituting the superconducting wire is 1 micron or less.

As a method of manufacturing a wire for superconducting connection,
The oxide powder is embedded in a metal sheath having a plurality of holes, and such a composite is rolled or stretched to be thinned, and heat-treated, and further cut by performing a cutting process in the longitudinal direction of the wire. To form.

Alternatively, the superconducting connection wire is a flat rectangular wire having superconductivity for electrically connecting the superconducting circuit chip, the semiconductor circuit chip, and a package, a substrate, or a superconducting wire such as a superconducting coil to each other. The superconducting wire has a structure in which the oxide superconducting layer is layered with the metal layer interposed therebetween, and the width of the layer is larger than the thickness of the entire layer.

In such a superconducting connection wire,
The average distance between the oxide superconducting layers forming the superconducting wire is 1 micron or less.

Alternatively, as a method for producing a wire for superconducting connection, an oxide superconducting layer and a metal layer are deposited on a flat metal plate, and the oxide superconducting layer and the metal layer are alternately deposited to form a manufacturing process. As a result, a step of cutting the laminated film in the longitudinal direction of the wire is included.

In these superconducting connecting wires, the metals forming the superconducting wires are Ag, Au, Pt, Re and R.
h, Pd, or an alloy of these. Furthermore, in these superconducting connecting wires, the superconducting material forming the thin wire made of superconducting fine particles is Y, B
a, an oxide composed of Cu, Bi, Sr, Ca and Cu
And an oxide composed of Tl, Ba, Ca and Cu, or an oxide composed of the same type of crystal structure as these oxides.

In these superconducting connecting wires, in the superconducting circuit chip, the semiconductor circuit chip, the superconducting package or the substrate, the part to which the superconducting wire is connected is made of the same material as the constituent material used for the superconducting wire.

[0015]

The superconducting connecting wire according to the present invention utilizes the superconducting proximity effect between the oxide superconductor and the metal and the melting property of the noble metal. That is, even if the conventional metal wiring wire is replaced with an oxide having superconducting properties, it is clear that the wire material lacks bending resistance and connectivity with wiring pads on the substrate.

Due to the superconducting proximity effect, the material constituted by the composite of the metal and the oxide superconducting material has not only the oxide but also the metal layer having the superconducting property. The superconducting distance in the metal layer depends on the type of metal material, but is several hundred nanometers from the interface between the metal and the oxide superconducting material. Therefore, if the metal layer is made of a composite of a metal and an oxide superconducting material so that the thickness of the metal layer is submicron, superconductivity can be maintained from the interface of the metal layer in contact with the oxide superconductor to the surface of the metal. If the thickness of the metal layer is 1 micron or more, the superconducting current cannot flow to the surface layer of the metal due to the proximity effect.

A superconducting connection needs to be made between the superconducting wire and the in-chip wiring pad. As will be described later, the mechanical connection between the superconducting wire and the in-chip wiring pad is made by the noble metal in the superconducting wire. That is, the noble metal portion in the superconducting wire is in direct contact with the in-chip wiring pad. As in the present invention, if the distance between the superconducting thin wires is 1 micron or less, the superconducting property, that is, the superconducting current contribution, is generated from almost all the superconducting thin wires at the connecting portion.

Even when discontinuity occurs between oxide particles in the superconducting thin wire, the particles are connected in a superconducting state via the noble metal due to the superconducting proximity effect. This also applies to the generation of discontinuity between particles in the superconducting wire manufacturing process, especially in the rolling and drawing process, or the cutting of superconducting thin wires due to excessive bending of the wire when connecting the superconducting wire to the substrate. , To ensure that the superconducting characteristics are maintained.

A superconducting wire consisting only of an oxide superconducting wire lacks bending resistance as a wire rod and connectivity with a wiring pad on a substrate. On the other hand, in a superconducting wire having a structure in which a plurality of superconducting thin wires according to the present invention are embedded inside a noble metal, the noble metal has durability against bending,
Responsible for mechanical connection with the wiring pad on the board. It is effective that the diameter of the superconducting thin wire can be made small and the possible bending radius can be made small because the superconducting thin wire is not a single layer but a plurality of superconducting wires. Ag, Au, Pt, R
Materials such as e, Rh, and Pd are excellent in such bending resistance and connectivity with wiring pads on the substrate.

These noble metal materials can be brought into close contact with the wiring pads on the substrate by heating with ultrasonic vibration. The surface layer of the wiring pad on the substrate is Ag, Au, P
When coated with the same material as that of the superconducting wire such as t, Re, Rh, Pd, etc., the adhesion by ultrasonic bonding is further improved.

Y, Ba as fine wires made of superconducting fine particles
When an oxide of Cu and Cu is used, a current capacity of 10 4 ampere or more can be easily obtained if the fine particles are in close contact with each other at the atomic level. When connecting the superconducting thin wire and the in-chip wiring pad via a precious metal,
If the thickness of the precious metal separating them is submicron,
The damping ratio of the superconducting current can be suppressed to 1/100 or less. Even with respect to the fine particles in the superconducting thin wires, the superconducting current can flow by the superconducting proximity effect even if they are not in close contact with each other.

Therefore, the capacity of the superconducting current obtained between the superconducting thin wire and the in-chip wiring is exclusively determined by the area of the superconducting thin wire facing the substrate surface via the noble metal. As in the present invention, it is effective in increasing the facing area that the number of superconducting thin wires in the superconducting wire is plural. Further, as in the present invention, it is more effective in terms of the contact area if the superconducting wire has a rectangular cross-sectional shape and the flat portion is in contact with the in-chip wiring. With such a method, it is possible to obtain a current capacity of 1 milliamperes or more required for superconducting connection of the superconducting circuit chip to an external device.

In the superconducting connecting wire, the superconducting material constituting the superconducting thin wire is an oxide containing Y, Ba and Cu, an oxide containing Bi, Sr, Ca and Cu, and T.
Of course, an oxide composed of 1, Ba, Ca and Cu, or an oxide composed of the same type of crystal structure as those oxides is suitable and effective for operation near the temperature of liquid nitrogen.

[0024]

EXAMPLES The present invention will be described based on the following examples.

(Example 1) As shown in FIG. 1, the first step for producing a superconducting wire is to first form Y-Ba-Cu oxide superconducting fine powder. As the Y-Ba-Cu oxide superconducting fine powder, Y oxide, Ba carbonate and Cu oxide powders are weighed to a predetermined weight and mixed. The mixed powder thus mixed is subjected to heat treatment at 1050 ° C. for 1 hour in an atmosphere of oxygen at 1 atmosphere, and then gradually cooled at a rate of 30 minutes per 100 ° C.
As a result, Y-Ba-C showing a superconducting critical temperature of 90K is obtained.
A u-oxide superconducting material is obtained.

The Y-Ba-Cu oxide superconducting material is pulverized by a liquor machine to obtain fine powder having a particle size of 0.5 cron or less. Furthermore, this oxide fine powder is added again to 8 degrees Celsius.
A heat treatment is carried out at 00 ° C. in an atmosphere of oxygen for 5 hours for 5 hours to relax the stress generated during the pulverization, remove defects in the crystal structure, and restore the superconducting properties such as the critical temperature and the critical current density. On the other hand, 0.2 mm diameter for Au wire with a diameter of 5 mm
Through holes are formed at substantially equal intervals. The hole is filled with the Y-Ba-Cu oxide powder previously formed and embedded. Such composite material is subjected to a press treatment to obtain Au and Y-Ba-C.
Improves the adhesion of u oxide. The Au wire in which the Y-Ba-Cu oxide is embedded is drawn to reduce the diameter of the composite wire. By repeating such wire drawing, the composite wire is reduced until the wire diameter becomes 0.5 mm. In this state, the composite wire is heat-treated at 600 degrees Celsius and 1 atmosphere of oxygen for 20 hours.
Further, this composite wire is rolled, and the rolling process is repeated until the cross-sectional area is 1/10 or less and the thickness is 30 microns or less. Next, cut the rolled composite wire in the longitudinal direction,
The width is 50 to 100 microns. Through these steps, as shown in FIG. 2, Y-Ba-Cu is obtained.
A fine wire 1 made of fine particles of oxide is embedded between Au base materials 2 to obtain a superconducting wire having a thickness of the superconducting fine wire of 1 micron or less and an interval between the fine wires of 1 micron or less.

The superconducting wire obtained by such a manufacturing process can pass a superconducting current of 2 milliamperes at a liquid nitrogen temperature. An ultrasonic bonder is used to connect the superconducting wire between the superconducting circuit chip and the chip package. The pad portion of the superconducting circuit chip has a structure in which an Au thin film is laminated on a Y-Ba-Cu oxide thin film. The superconducting current of the superconducting wire is hardly reduced in the connecting step. When the wiring of the chip package is superconducting, the superconducting circuit chips mounted on the package are connected in a superconducting state.

(Example 2) In the second step of producing a superconducting wire, as shown in Fig. 3, Y-Ba-Cu oxide superconducting fine powder is produced. As the Y-Ba-Cu oxide superconducting fine powder, Y oxide, Ba carbonate and Cu oxide powders are weighed to a predetermined weight and mixed. Mix the mixed powder with oxygen 1
In an atmosphere of atmospheric pressure, heat treatment is performed at 1050 degrees Celsius for 1 hour, and is gradually cooled at a rate of 30 minutes per 100 degrees. Thus, a Y-Ba-Cu oxide superconducting material having a superconducting critical temperature of 90K is obtained. The Y-Ba-Cu oxide superconducting material is pulverized by a liquor machine to obtain fine powder having a particle size of 0.5 cron or less. Further, this oxide fine powder is heat-treated again at 800 ° C. and 1 atm of oxygen for 5 hours to relieve the stress generated at the time of crushing, remove the defects of the crystal structure, and reduce the critical temperature and the critical current density. Restores superconducting properties. A groove having a width and a depth of 0.2 mm is formed on an Au plate having a thickness of 0.4 mm. The groove is filled with the Y-Ba-Cu oxide powder previously formed and embedded. Further, a 0.2 mm thick Au plate is covered. The rolling and stretching of such a composite material of oxide and Au are repeated. When the composite thickness is reduced to 50 microns, 50 layers of such composite are stacked. 6 degrees Celsius on the composite line in this state
Heat treatment is carried out at 00 ° C. in 1 atmosphere of oxygen for 20 hours. Repeated rolling and stretching of the laminated composite material
The thickness of the u layer is 1 micron or less. As the final step,
Cut the flat composite to the required width. By such a process, the structure similar to that shown in FIG. 2 is obtained,
A superconducting wire is obtained in which the thickness of the superconducting layer made of Y-Ba-Cu oxide particles is 1 micron or less and the distance between the superconducting layers is 1 micron or less. Using this superconducting wire, a minute magnetic field detecting device as shown in FIG. 4 is manufactured. Diameter of superconducting wire 11 prepared in advance 2
The magnetic field detecting coil 13 is wound around the 0 mm glass cylinder 12 and fixed, and at the same time, a differential coil whose winding directions are opposite to each other is produced in the middle of the coil. Such a coil is attached to a superconducting pad 16 of a superconducting circuit chip 15 composed of a superconducting flux quantum interferometer 14 and the like, which is composed of two superconducting junctions and a superconducting loop which are prepared in advance,
Connect in two places with an ultrasonic bonder.

The two superconducting pads are connected to an input coil 17 arranged above the superconducting flux quantum interferometer via an interlayer insulating film. The pad part is A on the Y-Ba-Cu oxide thin film.
This is a structure in which u thin films are laminated. It was confirmed that the input coil and the magnetic field detection coil were connected by superconductivity and constituted an integral superconducting loop as a whole. Therefore, the magnetic field component distributed in the magnetic field detection coil space can be transmitted to the input coil without loss due to the Meissner effect.

In this embodiment, the case where the metal layer is Au has been described. However, in addition to Au as the metal layer, Ag, Pt, Re, Rh,
Even a metal made of Pd or an alloy thereof can be used as the metal layer of the superconducting wire. Further, as a superconducting layer, Bi-Sr-Ca-C other than Y-Ba-Cu oxide
Similar results can be obtained by using other oxide superconducting materials such as u oxide and Tl-Ba-Ca-Cu oxide.

[0031]

As described above, the superconducting connecting wire according to the present invention has the following effects.

(1) The superconducting circuit chip and the superconducting circuit chip, the superconducting circuit chip and the chip package or the substrate, or the wiring connection between the superconducting circuit chip and the semiconductor circuit chip can be connected in a superconducting state.

(2) Since even a very high-speed signal waveform of gigahertz or more can propagate a signal in a distortion-free and loss-free state, it enables chip-to-chip signal transmission for a high-speed signal processing circuit device.

(3) Since the input coil connected to the superconducting magnetic flux quantum interference device used for measuring a minute magnetic field and the magnetic field detecting coil can be connected in a superconducting state, the magnetic field signal detected by the magnetic field detecting coil is not attenuated. To improve the magnetic field detection sensitivity.

[Brief description of drawings]

FIG. 1 is a diagram illustrating a manufacturing process of a superconducting wire.

FIG. 2 is a cross-sectional structural diagram of a superconducting wire.

FIG. 3 is a diagram illustrating a manufacturing process of a superconducting wire.

FIG. 4 is a configuration diagram of a minute magnetic field detection device using a superconducting wire.

[Explanation of symbols]

1 ... Y-Ba-Cu oxide fine wire, 2 ... Au base material, 11 ...
Superconducting wire, 12 ... Glass cylinder, 13 ... Magnetic field detecting coil, 14 ... Superconducting flux quantum interferometer, 15 ... Superconducting circuit chip, 16 ... Superconducting pad, 17 ... Input coil.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Masahiko Hiratani 1-280, Higashi Koikeku, Kokubunji, Tokyo (72) Central Research Laboratory, Hitachi, Ltd. (72) Shoichi Akamatsu 1-280 Higashi Koikeku, Kokubunji, Tokyo Hitachi, Ltd. (72) Inventor, Hitoshi Imagawa, 1-280, Higashi Koigokubo, Kokubunji, Tokyo, Hitachi, Ltd., Central Research Laboratory, Hitachi, Ltd. (72) Akira Tsukamoto, 1-280, Higashi Koikeku, Kokubunji, Tokyo, Hitachi, Ltd.

Claims (5)

[Claims] 1. A superconducting connection wire used for wiring connection, wherein the wire comprises a plurality of fine wires made of oxide superconducting fine particles embedded in a metal. 2. The superconducting connection wire according to claim 1, wherein the wire electrically connects the superconducting circuit chips, the semiconductor circuit chips, the packages for mounting them, or the substrates. Characteristic superconducting wire. 3. The superconducting connection wire according to claim 1, wherein the metal forming the superconducting wire is Ag or A.
A wire for superconducting connection, which is u, Pt, Re, Rh, Pd, or an alloy thereof. 4. The superconducting connection wire according to claim 1, wherein the superconducting material constituting the fine wire made of the superconducting fine particles is an oxide made of Y, Ba, Cu, Bi, Sr,
A wire for superconducting connection, characterized by comprising an oxide composed of Ca and Cu, an oxide composed of Tl, Ba, Ca and Cu, or a crystal structure of the same system as these oxides. 5. The superconducting connection wire according to claim 1, wherein the fine wires made of oxide fine particles constituting the superconducting wire have an interval of 1 micron or less.