JPH08204244A - Superconductive unit - Google Patents

Abstract

PURPOSE: To obtain a highly reliable superconductive unit comprising an Nb electrode of superconducting integrated circuit connected, through wireless bonding, with the wiring on a board while sustaining superconductive contact by suppressing the aging at a joint upon exposure to an environment of severe temperature cycle. CONSTITUTION: The Nb electrode face A is connected with the wiring face B of a board through a connection member 5 comprising a Pb alloy 5a having superconductivity formed continuously between them and a bonding bump 5b formed while being connected with both faces A, B. Consequently, the bonding strength is enhanced between the bonding bump 5b and the Nb electrode 2, the Pb alloy 5a and the wiring 4 on the board. Furthermore, the bonding bump 5b serves as a reinforcing member for the connection member 5 on the Nb electrode face A which is subjected to aging.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a superconducting device, and more specifically, it connects a Nb electrode of a superconducting integrated circuit and a wiring on a substrate by a wireless bonding method, particularly a flip chip bonding method or a tape carrier bonding method. In this case, the present invention relates to a superconducting device in which the reliability of the connection is improved while maintaining the superconducting connection.

[0002]

2. Description of the Related Art Conventionally, there is known a method of connecting electrodes of a superconducting integrated circuit in a superconducting device and wiring on a substrate (substrate wiring) by a wireless bonding method using a bump material having superconductivity. Has been. Here, forming the electrode of the superconducting integrated circuit with the Nb layer is preferred because the forming process is easy. Further, when connecting the Nb electrode of the superconducting integrated circuit and the substrate wiring,
In order to maintain the superconducting contact, a thin film of Au, Pd or the like is formed on the upper surface of the Nb electrode of the superconducting integrated circuit and used.

Further, since such a superconducting device is exposed to a severe temperature cycle (4.2K to 273K) from super-low temperature to normal temperature for exhibiting superconductivity, the reliability of the connecting portion is high. Especially important. Therefore, the inventors of the present application provide a highly reliable superconducting device by improving the bonding strength by forming an Au ultrathin film or Pd ultrathin film having a predetermined thickness on the Nb electrode of the superconducting integrated circuit. Was previously proposed (Japanese Patent Laid-Open No. 3-12941 (Japanese Patent Publication No. 6-5686).
0), JP-A-5-102538). However, in recent years, a superconducting device with even higher reliability at the connection part, that is, a superconducting device with extremely little deterioration with time in the connection part, even when exposed to a severe temperature cycle environment from extremely low temperature to room temperature, has been developed. It has been demanded.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned circumstances, and is a connection material (bump material) having superconductivity between the Nb electrode of the superconducting integrated circuit and the wiring on the substrate. By the wireless bonding method using
In a superconducting device connected while maintaining superconducting contacts, when exposed to a severe temperature cycle environment,
To provide a superconducting device that is even more excellent in terms of reliability of the connection part, in other words, a superconducting device that has extremely small deterioration over time in the connection part, as compared to a means that supports maintenance of the superconducting contact simply by forming an ultrathin film. To do.

[0005]

In order to achieve the above object, the superconducting device of the present invention is characterized in that, in claim 1, the Nb electrode surface of the superconducting integrated circuit and the wiring surface on the substrate (substrate wiring). A connecting member for connecting with the surface) is formed continuously between the Nb electrode surface and the substrate wiring surface and has superconductivity.
It is characterized by comprising a b alloy and a bonding bump formed by connecting at least the Nb electrode surface. In claim 1, the case where the Pb alloy and the bonding bump are directly connected to the Nb electrode of the superconducting integrated circuit, and the ultrathin film made of Au or Pd on the upper surface of the Nb electrode of the superconducting integrated circuit. And the case where the Pb alloy and the bonding bump are formed by being connected to the Nb electrode via the ultrathin film.

A second aspect of the present invention is characterized in that the Pb alloy and the bonding bump are directly connected to the Nb electrode of the superconducting integrated circuit. The term "formed by direct connection" as used in claim 2 refers to N of a superconducting integrated circuit.
It means that the Pb alloy and the bonding bumps are directly formed on the upper surface of the Nb electrode without forming an ultrathin film on the upper surface of the b electrode.

A third aspect of the present invention is characterized in that the bonding bumps are formed by connecting to both the Nb electrode surface of the superconducting integrated circuit and the substrate wiring surface.

According to a fourth aspect of the present invention, the bonding bump is A
It is characterized by comprising at least one of u, Ag, Pt, and Pd.

[0009]

The present invention will be described in detail below. The present invention relates to a superconducting device in which a superconducting integrated circuit having a Josephson junction and substrate wiring are connected by a wireless bonding method using a Pb alloy having superconductivity.
A representative example of the present invention is shown in FIGS. In FIG.
Reference numeral 1 is a superconducting integrated circuit made of a Si chip, 2 is an Nb electrode formed on the superconducting integrated circuit 1, 3 is a substrate, 4 is a superconducting upper surface of a copper plate wiring 4a formed on the substrate 3. Substrate wirings 5 plated with the underlying metal 4b are a connecting member composed of a Pb alloy 5a having superconductivity and a bonding bump 5b. The connecting member 5 is the Nb electrode 2
Of the Nb electrode surface (the surface indicated by symbol A in the figure) and the upper surface level of the substrate wiring 4, that is, the substrate wiring surface (the surface indicated by symbol B in the figure).
FIG. 2 shows an extremely thin film 7 on the Nb electrode 2 in the example shown in FIG.
In this example, the upper surface level of the ultrathin film 7 corresponds to the Nb electrode surface A.

In the present invention, the electrode 2 of the superconducting integrated circuit 1 is made of Nb. Forming the electrode 2 with Nb is preferably used because the forming process is easy.
In the present invention, as shown in FIG. 2, an ultrathin film 7 may be formed on the Nb electrode 2 and used. When the ultrathin film 7 is formed, its thickness is 200 nm or less. 200n
If it exceeds m, superconducting contact cannot be made, which is not preferable. The material of the ultrathin film 7 is Au or Pd.
Is preferably used. These ultra-thin films are formed on the Nb electrode 2 by vapor deposition or sputtering. FIG.
As shown in, an ultrathin film 7 is formed on the Nb electrode 2 of the superconducting integrated circuit 1.
Without forming the Pb alloy 5a and the bonding bump 5b directly to the Nb electrode 2 and as shown in FIG.
An extremely thin film 7 is formed on the b-electrode 2, and P is formed through the extremely thin film 7.
In the case where the b alloy 5a and the bonding bump 5b are indirectly connected to the Nb electrode 2, the same effect can be obtained with respect to the improvement of the reliability of the connection portion which is an object of the present invention, but the ultrathin film 7
As compared with the example of FIG. 2 in which the cost can be increased by forming the structure, the structure of FIG. 1 (according to claim 2) is more preferably used.

The substrate wiring referred to in the present invention means a substrate 3 made of plastic or ceramics provided with wiring having superconductivity. Preferably, as shown in the figure, the copper plate wiring 4a is plated with a base metal 4b having superconductivity to be used as the substrate wiring 4. Pb-as the base metal 4b
Plating of Sn or the like can be preferably used.

The term "connecting member" as used in the present invention refers to a member comprising a Pb alloy 5a having superconductivity and a bonding bump 5b. The Pb alloy having superconductivity is a Pb alloy capable of exhibiting a superconducting state at a liquid helium temperature (4.2K). Considering the workability of Pb alloy, Cu, Ga,
Ge, Se, Ag, In, Sn, Sb, Te, Au, T
Pb alloy containing 1, Bi, Pd, Pt is preferably used. The Pb alloy 5a having superconductivity is continuously formed between the upper surface level of the Nb electrode 2 of the superconducting integrated circuit 1, that is, the Nb electrode surface A and the upper surface level of the substrate wiring 4, that is, the substrate wiring surface B. It is necessary to form and secure the superconducting contact. At least one of Au, Ag, Pt, and Pd is used as the material for forming the bonding bump.
Seeds are preferably used. When these materials are used, the bonding force between the bonding bump 5b and the Nb electrode 2, the bonding bump 5b and the base metal 4b, and the bonding bump 5b and the superconducting Pb alloy 5a is surely improved. Connection member 5 including Pb alloy 5a having conductivity and bump 5b for bonding
The joining force of is improved.

In the present invention, the bonding bumps must be formed so as to be connected to at least the Nb electrode surface A of the superconducting integrated circuit 1. 3A to 3C can be exemplified as the connection points (connection method) of the bonding bumps 5b. In FIG. 3A, the bonding bumps 5b are formed by connecting to both surfaces of the Nb electrode surface A and the substrate wiring surface B of the superconducting integrated circuit 1, and between the Nb electrode surface A and the substrate wiring surface B. Is a continuously formed state. FIG. 3B shows a bump 5b for joining.
However, although it is formed by connecting both sides of the Nb electrode surface A and the substrate wiring surface B of the superconducting integrated circuit 1, the Nb electrode surface A and the substrate wiring surface B are not continuously formed. is there. The connection method is the same as that shown in FIGS. FIG. 3C shows a state in which the bonding bumps 5 b are formed by connecting only to the Nb electrode surface A of the superconducting integrated circuit 1. Of the connection methods shown in FIGS. 3A to 3C, as shown in FIGS. 3A and 3B, the bonding bumps 5b are connected to both the Nb electrode surface A and the substrate wiring surface B. Is preferably formed because the superconducting device is less deteriorated with time when exposed to a temperature cycle environment.

In FIGS. 3A to 3C, Pb
The alloy 5a and the bonding bump 5b are N of the superconducting integrated circuit 1.
Although the case where it is formed by being directly connected to the b electrode 2 has been shown, in the claim 1 of the present invention, the ultrathin film 7 made of Au or Pd is formed on the upper surface of the Nb electrode 2 and the ultrathin film 7 is interposed therebetween. The Pb alloy 5a and the bonding bump 5b are the Nb electrode 2
2 also includes a structure formed by connecting to each other, the structure is shown in FIG. 2 only for the connection method according to FIG. 3B, and the connection method according to FIGS. 3A and 3C is omitted for convenience. To do.

As a method of connecting the Nb electrode surface A and the substrate wiring surface B of the superconducting integrated circuit 1 with the connecting member 5, that is, an example of the method of forming the connecting member 5, the Nb electrode surface A and the substrate wiring surface B are connected. A so-called flip-chip bonding may be performed in which the bonding bumps 5b and the Pb alloy 5a are sequentially preliminarily formed, and then the Nb electrode surface A and the board wiring surface B on which the bonding bumps 5b and Pb alloy 5a are preformed are bonded. . Above Pb
As a method of preforming the alloy 5a and the bonding bump 5b, FIGS. 4A to 4C can be exemplified.

FIG. 4A shows a bonding bump 5 on the Nb electrode surface A of the superconducting integrated circuit 1 by using a wire bonding method.
Pb alloy 5 with superconductivity only by preforming b
“A” indicates a state in which no film is formed. Similarly, on the board wiring surface B, the bonding bumps 5b can be preliminarily formed. FIG.
(B) shows that the bonding bumps 5b are preliminarily formed on the Nb electrode surface A of the superconducting integrated circuit 1 by the wire bonding method,
After that, dip it in a superconducting Pb alloy bath,
A state in which the Pb alloy 5a having superconductivity is preformed so as to cover the preformed bonding bump 5b is shown. The bonding bumps 5b and the Pb alloy 5a can be similarly formed on the board wiring surface B as well. FIG. 4C shows that the bonding bumps 5b are preliminarily formed on the Nb electrode surface A of the superconducting integrated circuit 1 by using the wire bonding method, and further, by using the wire bonding method, the Pb alloy having superconductivity is used. A state is shown in which the Pb alloy 5a having superconductivity is preformed so as to cover the preformed bonding bump 5b. The bonding bumps 5b and the Pb alloy 5a can be similarly formed on the board wiring surface B as well.

In the present invention, when connecting the Nb electrode surface A and the substrate wiring surface B, it is preferable to use the method shown in FIG. 4 (b) or (c) on at least one of the both surfaces A, B. . That is, the Pb alloy 5a having superconductivity is continuously formed between the Nb electrode surface A and the substrate wiring surface B, and the bonding bumps 5b are connected to at least one of the Nb electrode surface A and the substrate wiring surface B. 4 (b) or (c), at least one of the Nb electrode surface A and the substrate wiring surface B has the structure of FIG. A method using a combination having any of the configurations of c) is preferably adopted. The most preferable combination is for both the Nb electrode surface A and the board wiring surface B as shown in FIG.
(B) or the configuration of FIG. 4 (c). The Nb electrode surface A and the board wiring surface B having the combination of the Pb alloy 5a and the bonding bump 5b preformed in this way
Are subjected to flip chip bonding by thermocompression bonding or reflow processing to obtain the superconducting device of the present invention.

When the method shown in FIGS. 4 (b) and 4 (c) is adopted, the difference in height between the preformed Pb alloy 5a and the bonding bump 5b is appropriately adjusted,
The connection member 5 shown in FIG. 3A or FIG. 3B can be formed separately. The smaller the height difference between the preformed Pb alloy 5a and the bonding bump 5b, the more the difference in the height of FIG.
It becomes easy to form the connecting member 5 shown in FIG. In addition, FIG.
Needless to say, when the connecting member 5 shown in FIG. 4 is formed, the methods shown in FIGS. 4A to 4C are appropriately combined without forming the bonding bump 5b on the substrate wiring surface B.

Further, in FIGS. 4A to 4C, the Pb alloy 5 is used.
Although the case where the a and the bonding bump 5b are directly connected to the Nb electrode 2 is shown, the same method as described above is applied to the case where the ultrathin film 7 made of Au or Pd is provided on the upper surface of the Nb electrode 2. Pb alloy 5a, bonding bump 5
It goes without saying that the connecting member 5 is formed by preforming b.

Thus, in the present invention, as described above, the connecting member 5 for connecting the Nb electrode surface A and the board wiring surface B is continuously formed between the Nb electrode surface A and the board wiring surface B. By adopting a configuration including the Pb alloy 5a having superconductivity and the bonding bump 5b formed by connecting at least the Nb electrode surface A, the obtained superconducting device is exposed to a temperature cycle environment. It is not clear why the deterioration with time is small when compared with the conventional method, but at least compared with the conventional case where a superconducting Pb alloy is directly formed on an ultrathin film on the Nb electrode to form a superconducting contact. By forming the bonding bumps 5b by connecting to the surface A, the bonding bumps 5b sufficiently serve as a reinforcing material for the connecting member 5 on the Nb electrode surface A, which is a weak point of deterioration over time. Thought to be That is, at least the Nb electrode surface A
By forming the bonding bumps 5b by connecting to the bonding bumps 5b, the bonding strength between the bonding bumps 5b and the Nb electrode 2 and the bonding bumps 5b and the Pb alloy 5a is improved, and the Pb alloy 5a having superconductivity is formed. It is presumed that the joining force of the connecting member 5 including the joining bumps 5b and the joining bumps 5b is improved as compared with the conventional case. When the bonding bumps 5b are formed by connecting to both the Nb electrode surface A and the substrate wiring surface B, the bonding bumps 5b and the Nb electrodes 2, the bonding bumps 5b and the substrate wiring 4, the bonding Bump 5b and Pb alloy 5a having superconductivity
It is presumed that the joining force of the connection member 5 and the joining force of the connecting member 5 are further improved. Further, the bonding bump 5b
Is formed by connecting both sides of the Nb electrode surface A and the board wiring surface B, and is continuously formed between the Nb electrode surface A and the board wiring surface B, the bonding bumps 5b and the Nb electrode are formed. 2,
It is presumed that the bonding force between the bonding bumps 5b and the substrate wiring 4 and between the bonding bumps 5b and the Pb alloy 5a having superconductivity is significantly improved, and the bonding force of the connection member 5 is significantly improved.

[0021]

EXAMPLE An example of the present invention in which the substrate wiring 4 is formed by plating the copper plate wiring 4a with the base metal 4b having superconductivity will be described below. (Example 1) In this example, as described in the connection conditions of Tables 1 and 2, as a material of the connecting member 5, Pb alloy 5a having superconductivity and Pb-In-Ag were used.
Au was used for the bonding bumps 5b. The connection method of the bonding bumps 5b is shown in (b) of each section shown in FIGS. 3 (a) to 3 (c), that is, the surface to be connected is the Nb electrode surface A (A surface in the table). And the substrate wiring surface B (indicated by B in the table), and the continuity between these two surfaces (A and B) was discontinuous. Further, thermocompression bonding is used when flip-chip bonding the connecting members (Pb alloy 5a, bonding bumps 5b) preformed on the Nb electrode surface A and the substrate wiring surface B, respectively, and an extremely thin film is formed on the Nb electrode 2. 7 was not formed.

A method of manufacturing the superconducting device of this embodiment adopting such connection conditions will be described with reference to FIG. 5. In FIG. 5A, reference numeral 1 is a superconducting integrated circuit made of a Si chip, Reference numeral 2 is an electrode made of an Nb layer, 3 is a substrate made of ceramics, and 4 is a substrate wiring formed by plating a copper plate wiring 4a formed on the substrate 3 with a base metal 4b having superconductivity. First, the bonding bump 5b made of Au is preliminarily formed on the upper surface level of the Nb electrode 2 of the superconducting integrated circuit 1, that is, on the Nb electrode surface A. The bonding bumps 5b are inserted in a capillary (not shown) of the wire bonder.
A ball is formed by heating the tip of the wire with an electric torch, and the ball is pressed onto the Nb electrode 2 to pull up the wire by a capillary to cut the ball from the root of the wire. Formed on 2. Further, by using a Pb alloy having a superconductivity made of Pb-In-Ag, the Pb alloy 5a having a superconductivity having a size larger than that of the bonding bump 5b is formed by the ball bonding method as described above. 5b was covered and pre-formed on the Nb electrode surface A. next,
The bonding bumps 5b and the superconducting Pb alloy 5a were also preliminarily formed on the upper surface level of the base metal 4b in the substrate wiring 4, that is, on the substrate wiring surface B in the same manner as described above. After that, the structure shown in FIG. 5A is flip-chip bonded by thermocompression bonding to obtain the structure shown in FIG.
As shown in (b), the Pb alloy 5a having superconductivity is continuously formed between the Nb electrode surface A of the superconducting integrated circuit 1 and the substrate wiring surface B, and the bonding bumps 5b are the Nb electrodes. A connecting member 5 is formed which is connected to both the surface A and the board wiring surface B and in which the respective bonding bumps 5b and 5b are not continuous, whereby the superconducting integrated circuit 1 and the board wiring 4 are formed by the connecting member 5. The superconducting device of the present example was obtained in which and were connected with high reliability while maintaining the superconducting connection.

A thermal cycle test (at a temperature of 4.2K to 273K) of the superconducting device according to this example was conducted, and the number of times at which the superconducting contact could not be removed was measured at a temperature of 4.2K. The above connection conditions and measurement results are shown in Tables 1 and 2.

(Examples 2 to 9) Tables 1 and 2 show the material of the connecting member 5, the connection method of the bonding bumps 5b, the distinction between the thermocompression bonding used in the flip chip bonding and the reflow treatment.
A superconducting device was produced by flip-chip bonding in the same manner as in Example 1 except that the connection conditions were as described above. A thermal cycle test was conducted on the obtained superconducting device in the same manner as in Example 1. The measurement results are shown in Table 2.

(Examples 10 and 11) Flip-chip bonding was performed in the same manner as in Example 3 except that an ultrathin film 7 of Au or Pb having a thickness of 100 nm was formed on the Nb electrode 2 of the superconducting integrated circuit 1. , A superconducting device was produced. A thermal cycle test was conducted on the obtained superconducting device in the same manner as in Example 1. The connection conditions and measurement results are shown in Tables 1 and 2.

Comparative Examples 1 and 2 An extremely thin film of Au or Pb having a thickness of 100 nm is formed on the Nb electrode of a superconducting integrated circuit, and the Nb electrode having the extremely thin film and the substrate wiring are
A superconducting device was manufactured by flip-chip bonding using thermocompression bonding with a connecting material composed only of Pb alloy (Pb-In-Ag) having superconductivity. A thermal cycle test was conducted on the obtained superconducting device in the same manner as in Example 1. The measurement results are shown in Table 2.

[0027]

[Table 1]

[0028]

[Table 2]

From the above results, the connecting member connecting the Nb electrode surface of the superconducting integrated circuit and the wiring surface on the substrate is formed continuously between the Nb electrode surface and the substrate wiring surface. In Examples 1 to 11 of the present invention, which are composed of a Pb alloy having a conductivity and a bonding bump formed by connecting to at least the Nb electrode surface, the number of thermal cycles until occurrence of a superconducting contact defect is 130 times or more. It can be seen that the superconducting device is connected with high reliability while maintaining the superconducting connection.

Example 3 in which the Pb alloy and the bonding bump are directly connected to the Nb electrode of the superconducting integrated circuit, and the Nb electrode is connected via the Au or Pd ultrathin film on the Nb electrode. When compared with Examples 10 and 11 formed as described above, the number of thermal cycles until the occurrence of a superconducting contact failure is 180 times or more, and regarding the improvement of the reliability of the connecting portion, which is an object of the present invention, It turns out that both are satisfied enough. Incidentally, the comparison of the presence or absence of the ultrathin film on the Nb electrode is shown only when the connection method of the bonding bumps is (b) in each of the sections (a) to (c) shown in FIG. It was confirmed that the same tendency was observed in the connection methods shown in FIGS. 3 (a) and 3 (c).

Furthermore, in Examples 1 to 3 and 5 to 11 in which the bonding bumps were formed by connecting to both the Nb electrode surface of the superconducting integrated circuit and the substrate wiring surface, the superconducting contact failure occurred. The number of heat cycles up to each is 170 times or more, and compared with the case where the bonding bumps are formed by being connected to either one of the Nb electrode surface and the substrate wiring surface of the superconducting integrated circuit (Example 4). It can be seen that it is more effective in improving the reliability of the connection portion.

Furthermore, when the bonding bumps are formed by connecting to both the Nb electrode surface and the substrate wiring surface of the superconducting integrated circuit, and the Nb electrode surface and the substrate wiring surface are continuously formed. In (Example 2), the number of thermal cycles until the occurrence of a superconducting contact failure is 200, and the bonding bump is Nb.
Although it is formed by connecting to both surfaces of the electrode surface and the board wiring surface B, compared to the case where it is not formed continuously between the Nb electrode surface and the board wiring surface (Examples 1, 3, 5 to 11) It can be seen that it is more effective in improving the reliability of the connection portion.

On the other hand, in Comparative Examples 1 and 2 in which the superconducting contact is maintained by the ultrathin film formed on the Nb electrode of the superconducting integrated circuit, the number of heat cycles until the superconducting contact failure occurs. 60 times and 100 times respectively,
Although the reliability of the connection portion is improved as compared with the conventional superconducting device that corresponds to the maintenance of superconducting contacts without forming the ultrathin film, it may be insufficient for the problem of the present invention. I understand.

[0034]

As described above, the present invention provides claim 1.
In the above, by a connecting member including a Pb alloy having superconductivity formed continuously between the Nb electrode surface and the substrate wiring surface and a bonding bump formed by connecting at least the Nb electrode surface, Since a new structure in which the Nb electrode surface of the superconducting integrated circuit and the wiring surface on the substrate are connected is adopted,
Compared to the conventional case where a Pb alloy having superconductivity is directly formed on an ultrathin film on an Nb electrode to form a superconducting contact, the bonding bump has a connecting member on the Nb electrode surface, which is a weak point of deterioration over time. Plays the role of a reinforcing material. Therefore, when exposed to a severe temperature cycle (4.2K to 273K) environment from super-low temperature to normal temperature for expressing superconductivity, deterioration of the connecting portion with time is smaller than that of the conventional one, and is extremely reliable. It was possible to provide a highly conductive superconducting device.

When the Pb alloy and the bonding bump are directly connected to the Nb electrode of the superconducting integrated circuit as in claim 2, the connecting portion is formed without forming an ultrathin film on the Nb electrode. The deterioration with time can be further reduced as compared with the conventional one, and the cost is lower than that in the case where the Pb alloy and the bonding bump are formed by being connected to the Nb electrode through the ultrathin film on the Nb electrode. There is an advantage that the above effects can be obtained.

Further, when the bonding bumps are formed by being connected to both the Nb electrode surface of the superconducting integrated circuit and the substrate wiring surface, the bonding bumps and the Nb electrode may be formed. The bonding force between the bonding bump and the substrate wiring, and the bonding bump and the superconducting Pb alloy are respectively improved, so that the bonding bump is provided on either the Nb electrode surface or the substrate wiring surface of the superconducting integrated circuit. Compared with the case where it is formed by connecting,
The joining force of the connecting member including the Pb alloy having superconductivity and the joining bump is further improved, and a superconducting device having extremely high reliability can be provided.

[Brief description of drawings]

FIG. 1 is an enlarged sectional view of an essential part showing an embodiment of a superconducting device according to the present invention.

FIG. 2 is an enlarged sectional view of an essential part showing another embodiment of the superconducting device according to the present invention.

FIG. 3 is an enlarged cross-sectional view of a main part showing a section of a connection method of bonding bumps.

FIG. 4 is an enlarged sectional view of an essential part showing a section of a method of preforming a Pb alloy having superconductivity and a bonding bump on an Nb electrode surface.

FIG. 5 is an enlarged sectional view of an essential part showing a state in which a Nb electrode surface on which a Pb alloy having superconductivity and a bonding bump are preformed and a substrate wiring surface are flip-chip bonded together.

[Explanation of symbols]

 1: Superconducting integrated circuit 2: Nb electrode 3: Substrate 4: Substrate wiring 4a: Copper plate wiring 4b: Base metal 5: Connection member 5a: Pb alloy having superconductivity 5b: Bonding bump 7: Nb electrode pole Thin film A: Nb electrode surface B: Substrate wiring surface

Claims (4)

[Claims] 1. A connecting member for connecting an Nb electrode surface of a superconducting integrated circuit and a wiring surface on a substrate has a superconductivity formed continuously between the Nb electrode surface and the substrate wiring surface. A superconducting device comprising a Pb alloy and a bonding bump formed so as to be connected to at least the Nb electrode surface. 2. The superconducting device according to claim 1, wherein the Pb alloy and the bonding bump are formed by being directly connected to the Nb electrode of the superconducting integrated circuit. 3. The super bump according to claim 1, wherein the bonding bumps are formed by being connected to both the Nb electrode surface of the superconducting integrated circuit and the substrate wiring surface. Transmission device. 4. The bonding bump is made of Au, Ag, P
The superconducting device according to claim 1, 2 or 3, wherein the superconducting device comprises at least one of t and Pd.