JPS5979585A - Manufacture of josephson junction element - Google Patents

Abstract

PURPOSE:To reduce the dispersion of the titled element' characteristics by a method wherein the total film thickness of a superconductive wiring layer, two electrode layers and a tunnel barrier layer held by the two electrode layers is decided to meet specific requirements. CONSTITUTION:An Nb film approximate 300nm thick is formed on an Si substrate 1 whereon an insulating layer 2 is formed and a gland plane 3 is formed by selective etching. Then an insulating layer 4 approximate 150nm thick and a lower wiring layer 5 made of an Nb film approximate 300nm thick are formed. Firstly another Nb film 6 approximate 50nm thick as the first superconductive electrode, a tunnel barrier layer 7 approximate 10nm thick and the other Nb film 8 approximate 50nm thick as the second superconductive electrode are formed making the total thickness of these three layered films amount to approximate 110nm. Secondly said three layered films are processed using a mask 9 and after forming an insulating layer with almost similar thickness to that of said three layered films, the mask 9 is lifted off. The area of a Josephson junction element so far produced is 5-1mum<2>. The dispersion of element' characteristics may be reduced by adopting the Josephson junction element.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to a Josephson 1-group junction device that operates at extremely low temperatures, and is particularly concerned with small variations in device characteristics and excellent reproducibility. This invention relates to the structure and manufacturing method of Josephson junction devices suitable for integration.

[Prior art]

In the Josephson junction device, after patterning the first superconducting electrode, its surface is cleaned by sputtering using Ar gas or the like, and then an oxide or insulating film of the first superconducting electrode material is formed. However, this sputtering causes defects on the surface of the lower electrode, and it is difficult to obtain reproducibility in removing contamination, which is an obstacle to improving the characteristics of Josephson junction devices. was. As a method for completely solving the problem of clumping, there is a method in which a first superconducting electrode is formed, a tunnel barrier layer is formed in the same bell jar, and then three layers of the second superconducting electrode are formed. this is
J, @1ark, Proc, Roy.

Soc, A308, pp447-471 (1969
).

5supercurrents in 1ead-Cap
This is a method of forming a tunnel barrier layer without producing unnecessary contamination or oxides on the surface of the first superconducting electrode, as seen in Per-1eadS and Witch.

This known example by J. C1ark uses a metal mask and rotates it to perform vapor deposition and patterning of three layers, and it cannot be used to fabricate integrated circuits containing fine patterns, and also requires interlayer insulation. Unless a film is used, it is difficult to form a superconducting wiring between other Josephson junction elements. One way to solve this problem is to
As disclosed by Sasaki et al. in Published Patent Publication No. 52-82090, the side surfaces of these three layers are oxidized to form an insulating film,
A method of forming superconducting wiring without shorting is known.

However, in addition to this method, it is not possible to form the necessary insulator film thickness to obtain a sufficient insulating layer.

Because a step of 1 μm or more occurs, the thickness of the superconducting thin film constituting the superconducting wiring needs to be at least 1 μm or more to avoid disconnection at this step, making it impossible to form a fine pattern. Therefore, the degree of integration must also be low. As a method for solving this problem, a method of flattening using an insulator is known.

Another drawback of the method of Sasaki et al. is that the accuracy of the area of the Josephson junction element determined by processing the core three-layer film is poor for microjunctions with a junction area of 5 μm 2 or less.

Also, 1(, Kroger (5elective n
iobinmanodization Process
for fabricating Josephson
tunnel junctions; Appl;
Phys.

Lett, 39C31, 280 (1981) invented a method of defining the Josephson junction by processing the three-layer film by anodic oxidation rather than etching. In this case, since a Nb anodic oxide film is used for the other edge film, the superconducting electrode material is limited to Nb, and since the Nb anodic oxide has a large dielectric constant, the floating dielectric of the Josephson junction The rate becomes large and becomes a serious obstacle to high-speed switching.

[Purpose of the invention]

An object of the present invention is to provide a structure of a Josephson junction element that solves the above-mentioned drawbacks of the prior art, has small variations in element characteristics, has excellent reproducibility, and is therefore suitable for manufacturing highly integrated circuits. The purpose is to provide an easy manufacturing method.

[Invention/Ready-made] In order to achieve the above object, the Josephson junction element of the present invention is made of a superconductor. A first electrode layer and a second electrode layer made of a superconductor have a junction formed by bonding a tunnel barrier layer with a glue, and the first electrode layer, the second electrode layer and the tunnel The side surfaces of the barrier layer are formed substantially on the same plane in the vertical direction, substantially the entire lower surface of the first electrode layer is in contact with the superconducting wiring layer, and the superconducting wiring layer cap has a magnetic field penetration distance greater than or equal to the magnetic field penetration distance of the superconducting material constituting it. , and the total thickness of the first electrode layer, the tunnel barrier layer, and the second electrode layer is approximately 10 times the square root of the area of the junction. It is configured to be less than one-fold.

the first electrode layer, the tunnel barrier layer and the second electrode layer;
If three layers consisting of electrode layers are embedded in the insulating layer and the upper surface of the second electrode layer and the upper surface of the core insulating layer do not form a step, the three electrode layers will be connected to the second electrode layer and the insulating layer will be connected to the second electrode layer. The upper superconducting wiring layer extending over the layer can be easily formed with good results.

Generally, SiO or Sio2 may be used for the insulating layer, but there is no need to limit it to this.

Further, the superconducting wiring layer and the first electrode layer are usually N
Good results can be obtained using b, but there is no need to limit it to this.

The method for easily manufacturing the Josephson junction device of the present invention includes: 1) forming a superconducting wiring layer on a substrate; 11) forming a superconducting layer to become a first electrode layer on the substrate having the superconducting wiring layer; , Step of successively forming an insulating layer or a semiconductor layer to become a tunnel barrier layer and a superconducting layer to become a second electrode layer to form a 13-layer film, 111) Nuclear Bin 3
A layer film is formed and processed to have a predetermined shape at a predetermined position on the superconducting wiring layer. After this, an upper superconducting wiring layer may be formed to connect circuit elements such as Josephson junction elements, resistors, etc., if necessary.

The Josephson junction element of the present invention includes a first superconducting electrode,
The tunnel barrier layer and the second superconducting electrode can be formed continuously without breaking the vacuum, and are then processed and processed.
The feature is that a Josephson junction can be produced in an ideal state by molding, and that the total thickness of the three layers mentioned above is particularly thin.

It has been found that the area of the Josephson junction element, which is determined by processing the three-layer film with a thickness of approximately 500 nm as seen in the prior art, is inferior in accuracy to micro-junctions with a junction area of 5 μm or less. .

The reason for this is that the thickness of each layer of the three-layer film is about the same as that of the wiring layer, which is too thick, as shown in the explanatory diagram of the example in Published Patent Publication Q52-82090, and that This is because it is difficult to process the three-layer film to have a substantially vertical cross section as shown in the explanatory diagram from the viewpoint of variation and reproducibility. This variation in cross-sectional shape causes variation in the junction area as shown in FIG. 1, and as a result, the value of the critical Josephson current flowing through the Josephson junction also varies. It was also found that this effect becomes more pronounced as the bonding area becomes finer. When the angle θ shown in FIG. 1 is distributed over 30° to 600° within one integrated circuit, the thickness of the three-layer membrane is d.

If the minimum value of the bonding area is e2, then the variation in the bonding area is about 2 (17!), and the ratio of the two is 2d/1. Therefore, to set the variation in the bonding area to within ±10% 1 meter, for example. It was found that d needs to be less than 1/10 of 4 in order to
The figure shows the same parts as the following drawings.

Incidentally, when processing is performed by dry etching, the angle θ is normally distributed in the range of 30' to 6o0 as described above. Further, in order to put the Josephson element into practical use, it is desirable that the variation in the junction area be within ±1'O%.

In the Josephson junction device of the present invention and its manufacturing method, conventional techniques may be followed for matters not mentioned above.

[Embodiments of the invention]

Hereinafter, the present invention will be explained in detail with reference to Examples.

As shown in Fig. Ff, 2, an Nb film with a thickness of about 300 nm was formed by sputtering on a Si substrate 1 whose surface was thermally oxidized with oxygen at a temperature of about 1100'0 to form an insulating layer 2, and then a photoresist film was formed. The ground plane 3 is processed using a chemical etching method using fluoronitric acid as a mask. Next, an insulating layer 4 made of a SiO film with a thickness of about 150 nm is formed.
．． A lower wiring layer 5 made of a Nb film with a thickness of about 300 nm is formed.

The Nb film of the lower wiring layer was formed by a sputtering method, and its processing used Ar ion etching using a photoresist mask. Next, after cleaning the surface of the lower wiring layer 5 by sputter etching with Ar ions,
Approximately 50 nm Nb film that becomes the first superconducting electrode 6. about 10
The tunnel barrier layer 7 made of a Si film with a thickness of about 5 nm is formed by sputtering to form a second superconducting electrode.
A 0 nm thick Nb film 8 is continuously formed by resistance heating vapor deposition without breaking the vacuum. This three-layer film was processed by ion etching the total of the three-layer film, and then, as shown in FIG. 3, an insulating layer 10 made of a Si film having approximately the same thickness as this three-layer film was formed. Afterwards, the mask 9 is lifted off with acetone.

The area of the Josephson junction element thus formed is 5 to 1 .mu.m.sup.2. Finally, as shown in FIG. 4, an upper superconducting wiring layer 1 made of a Pb film with a thickness of about 500 nm is
By forming 1, the Josephson junction device of the present invention could be manufactured.

FIG. 5 is a plan view of this from above, showing the 12-joint portion. The Josephson junction device manufactured in this manner has excellent reproducibility of device characteristics such as critical Josephson current and tunnel resistance values, and has little variation. Furthermore, when a logic circuit or a memory circuit was manufactured using this Josephson junction element, it was possible to improve the yield compared to the conventional method because variations in element characteristics could be reduced.

Note that, although it is desirable to use Nb as the first superconducting electrode material, it is not limited thereto. Further, in this example, Pb was used as the second superconducting electrode material, but the same effect could be obtained even if Nb was used.

As the insulator used for embedding the Josephson junction element, it is preferable to use SiO2 other than SiO. In the present invention, Nb can be used for the uppermost superconducting wiring, but when processing it by CF4 ion etching, the difference in etching rate between Nb and the insulating film is increased to selectively remove Nb. This is for etching.

In this example, the thickness of the first superconducting electrode is approximately 50 mm.
However, since the Nb film of the lower wiring has a thickness of 300 nm, the total of both is about 3500 m. In this way, if the total film thickness is made larger than the magnetic field penetration distance of Nb,
Even if the first superconducting electrode is thin, it does not affect the characteristics of the Josephson junction element. Therefore, since the total thickness of the three-layer film can be reduced, it is possible to improve the processing accuracy when processing the three-layer film by ion etching to form a joint portion.

When an integrated circuit was fabricated using the Josephson mating element fabricated in this way, it was found that there was little variation in device characteristics, and since the device was flattened, there was no disconnection of the superconducting wiring, improving yield and reducing delay time. We were able to create a circuit that operates at high speeds below I ops.

〔Effect of the invention〕

As described above, according to the present invention, defects are not generated on the superconductor surface in contact with the tunnel barrier layer of the Josephson junction element, and variations in the junction area can be reduced, which is a disadvantage of the conventional technology. This has the effect of solving the problems, improving the reproducibility of device characteristics, and improving yield.

Next, a second invention related to a Josephson junction element by the present inventors will be explained. Embodiments of the second invention are shown below.

(2) In a superconducting tunnel element composed of at least a lower electrode, an upper electrode, an insulating film between the upper electrode and the lower electrode having a junction opening, and an insulator or semiconductor barrier layer, a part of the lower electrode film, the barrier layer and the upper It includes a step of continuously forming a part of the electrode, and a step of removing all or a part of the formed three-layer film by etching to form a joint, and in the etching step, the etching step is performed twice. The etching process is performed separately, and the shape left by each etching process is made into a rectangular shape.
A method for manufacturing a superconducting junction element, characterized in that the rectangular pattern in the second etching step intersects with the rectangular pattern in the first etching step, and the intersecting portion is provided on the flat surface of the lower electrode film.

The invention in Bookcase 2 relates to a method for manufacturing a superconducting junction device, and in particular to a method for miniaturizing and highly customizing the device necessary to improve the high-speed performance of tunnel-type Josephson junction devices suitable for switching devices for high-speed computers. .

Conventionally, superconducting tunnel junction devices are manufactured in the following order: pattern formation of the lower electrode, film formation, pattern formation of the barrier layer portion, formation of the interlayer 1 insulating film, pattern formation of the upper electrode, formation of the barrier layer, and formation of the lower electrode film. It has been done. In such a process, a patterning step that contaminates the surface of each layer is involved during the formation of each layer.
It is necessary to remove the lower polluted layer before forming the upper layer.

In a contaminant layer removal process using sputtering or the like, it is impossible to completely remove the contaminant layer and prevent the atomic arrangement of the film surface layer from being disturbed. If such a contamination layer remains, the disordered atomic arrangement will affect the composition and structure of the oxide film that forms the barrier layer on the surface.
This leads to deterioration of reproducibility and deterioration of the voltage-current characteristics of the bond. As a method for preventing contamination from occurring during the film forming process, a method has been proposed in which a lower electrode, a barrier layer, and an upper electrode are sequentially formed in a vacuum apparatus. C1arke et al. (-5supercurrents
in 1ead-copper-1ead sidew
ich″Proc.

Roy, Soc, Vol. A, 308, p.
-p-447-471, 1969) is one of the first examples of this. Jacke'l et al. (+Submic
ron Tunnel Junctions"I EEE
Trans, MagoMAG-17, p, p,
295-298, 1981) is a method that allows miniaturization of this method by forming a tunnel junction resist pattern and then changing the deposition direction to form a lower electrode and an upper electrode. , forming a junction. However, this method has a problem in that the bonding area varies depending on the location of the vapor deposition direction because all or part of the end portion of the lower electrode film is not utilized. This also causes local variations in the Josephson critical current of the tunnel junction.

Therefore, the purpose of the invention in Bookcase 2 is to provide a method for manufacturing a superconducting tunnel junction device in which a lower electrode, a barrier layer, and an upper electrode are continuously formed without intervening a patterning process, in which the Josephson critical current value varies locally. It is an object of the present invention to provide a method for obtaining a bonding element with a small area free of defects.

In the invention in Bookcase 2, a lower electrode, a barrier layer, and an upper electrode are formed continuously, and a place where the lower electrode is flat is selected and etched to the continuously formed lower electrode layer, leaving a rectangular part. , the etched portion is backfilled with an oxide film. Alternatively, the surface of the metal film is oxidized to a sufficient thickness (>Ionm). At least the barrier layer is etched again leaving a rectangular portion, and the etched portion is backfilled with an oxide film.

The portion remaining after the two etching processes is used as a tunnel junction. By such a method, the area of the resist pattern for the etch jig can be increased and pattern formation possible, and the dimensional accuracy of the resist pattern can be improved, and pattern formation down to submicrons is possible.

The invention of the bookcase 2 will be explained below using examples.

The structure of the superconducting tunnel junction device in this example is shown in Figure 6.
It is shown in the figure. In the figure, N
A ground plane film 111 made of B film is formed,
An interlayer insulating film 112 made of a Nb anodic oxide film and a SiO film is formed on the ground plane film. A lower electrode film 113 which also serves as wiring is formed using Nb on the interlayer insulating film. Junction lower electrode on the flat surface of the lower electrode film,
A three-layer film 114 consisting of a barrier layer and an upper electrode is formed. The three-layer film consists of Nb, Nb oxide and Pbo, respectively.
In. Consists of 1 alloy. A SiO interlayer insulating film 115 is formed on the side surface of the three-layer film. Furthermore, the upper electrode film 1 is made of P b o 9 In o, which also serves as wiring, in the upper part of the three-layer film.
16 is formed.

Next, the manufacturing process of the invention for bookcase 2 will be shown below. As shown in FIG. 7, a ground plane Nb film 111 with a thickness of 300 nm was formed on a silicon wafer 110 by DC magnetron sputtering. A 90 nm thick Nb anodic oxide film and a 150 nm thick SiO vapor deposited film 112 are formed on the ground plane film 111. Next, a Nb layer 113 to be the lower electrode was formed to a thickness of 300 nm by DC magnetron sputtering, a resist pattern was formed, and then an Nb film pattern was formed by ion etching with Ar. Next, in a vacuum apparatus, the film surface was sputter-cleaned with Ar, and then a barrier layer was formed by magnetron sputtering of the Nb film with a thickness of 1100 nm, a barrier layer was formed by surface oxidation of the Nb film, and a Pbo9 film with a thickness of 1100 nm was formed by resistance heating. no
One film was formed, and a three-layer film 114 was formed. Next, as shown in Figure 8, it is long (7 μm in length) in the in-plane direction of the figure.
) 9 Form a rectangular resist pattern with a width of 15 μm,
Nb film layer 1 for wiring is formed by ion etching with Ar.
The etching progressed to 13.

With the resist film remaining, the SiO film 115 is coated with a thickness of 50 nm.
m vapor deposition, and the lift-off method was used to leave the parts other than the bonded parts. Next, as shown in FIG. 9, a rectangular resist pattern that is long in the direction perpendicular to the figure (length 7 m) and width 1.5 μm is formed, and the Nbi of the three-layer film 114 is etched by Ar ion etching. I continued etching until I reached it.

With the resist film remaining, the SiO film 115 is heated to 120nm.
rn vapor deposition, and the lift-off method was used to leave the parts other than the joints. Thereafter, the exposed surface layer of the three-layer film was oxidized by plasma discharge in an oxygen atmosphere. At this time, the Nb film is oxidized to be thicker than the PbO, 9'nO, 1 film.

Next, after forming a resist pattern for lift-off, sputter cleaning was performed using Ar in a vacuum apparatus. At this time, the surface of the Pbo91no1 film is completely removed, but since Nbi has a low sputtering rate, an oxide layer remains. After this, P b O, J' 1 n o 1 film was added to 400
The film was formed to a thickness of nm, and lift-off was performed to obtain a wiring film.

The superconducting tunnel junction manufactured by the above method had good uniformity of characteristics on a single wafer, and the fluctuation width of the Josephson critical current was within ±10 factors.

As mentioned above, in the method of constructing a superconducting bonding element according to the second invention, it is possible to fabricate a fine-sized bond (approximately 1 μm), and there is little local variation in characteristics on the wafer, and the direct current of the bonding element is small. High voltage-current characteristics (ratio of resistance R5 below the gap voltage to normal resistance Rhn" J
/ ” h n is 15 or more) has the effect of providing an element.

Next, a third invention related to a Josephson junction element by the present inventors will be explained. The third invention relates to an apparatus for manufacturing a superconducting element. Embodiments of the third invention are shown below.

■ In the structure of a superconducting tunnel junction device consisting of a superconducting lower electrode film, an upper electrode film, and a barrier layer sandwiched between them, 1. An apparatus for producing a superconducting element, comprising a vapor deposition apparatus, at least a loop separating a lower electrode film forming apparatus and an upper electrode film forming apparatus, and a apparatus for holding and transporting a weld forming the element.

2 In the first embodiment, the lower electrode film is an alloy mainly composed of Nb, the upper electrode film is an alloy mainly composed of Pb, the lower electrode forming apparatus is a sputtering apparatus or an electron beam evaporation apparatus, and the upper electrode forming apparatus is a resistor. A superconducting device manufacturing device characterized by being a heating or electron beam evaporation device.

3. The apparatus for manufacturing a superconducting element according to the first embodiment, wherein the barrier layer forming apparatus is a conductive electrode capable of applying a high frequency.

The third invention relates to an apparatus for manufacturing a superconducting junction element, and in particular to an apparatus for manufacturing a superconducting element suitable for forming a large number of junction elements on a substrate without changing characteristics.

In the conventional method of manufacturing superconducting tunnel junction devices,
Formation of resist pattern for lower electrode, formation of lower electrode film,
This process has been performed in the following order: forming a pattern (for an interlayer insulating film that determines the bonding area), forming an interlayer insulating film, forming a resist pattern for an upper electrode, and forming a barrier layer and an upper electrode film. In such a process, a patterning step that causes contamination of the film surface is inserted while the parts constituting the bonding element are being formed. ) or deterioration of junction characteristics (increase in leakage current). As a method to improve this, a method has been considered in which a lower electrode film, a barrier layer, and an upper electrode are successively formed, and then a pattern of the bonding portion is formed by etching or anodic oxidation of the electrode film. Nb- of Kroger et al.
Method of forming amorphous Si-,Nb junction ("Sel
ectiveniobium ano+1izatio
n process for fabricating
゛Josephson tunnel junction
ns″Appl, Phys.

Lett, Vol. 3-9 p. 280. 1981) is one of these methods. However, in order to obtain a junction element with low leakage current, it is desirable to use a low melting point metal such as a Pb alloy, which does not damage the barrier layer due to thermal radiation during the formation of the electrode film, as the upper electrode. There was no apparatus capable of continuously forming a film of a high melting point metal, a barrier layer, and a film of a low melting point metal in the same vacuum chamber.

Therefore, the purpose of the invention in Bookcase 3 is to provide a lower electrode of a superconducting tunnel junction element, such as a Nb-oxide-Pb alloy junction, in which the lower electrode is a high melting point metal and the upper electrode is a low melting point metal.
It is an object of the present invention to provide a structure of an apparatus that enables continuous formation of a barrier layer and an upper electrode three-layer film.

The invention in Book Box 3 includes a sputtering or electron beam evaporation device for the lower electrode, a resistance heating or electron beam evaporation device and a barrier layer forming device for the upper electrode, a device for supporting and transporting the substrate, and a lower electrode film. It is possible to form a three-layer film by using a device having a gate valve that partitions between the forming device for forming the film and the device for forming the lower electrode film. By using such an apparatus, it is possible to prevent the low melting point metal film from adhering to the wall near the high melting point metal film forming apparatus and from mixing the low melting point metal element into the formed high melting point metal film.

The invention of the bookcase 3 will be described below based on examples.

First, FIG. 10 shows a schematic diagram of the device according to the invention of the bookcase 3. In the figure, the vacuum device is divided into two chambers, each with its own exhaust device. The first chamber includes a resistance heating device 201 for evaporating PB and In. A roller 205 for feeding the substrate tray and a high frequency electrode 206 for plasma discharge to form an oxide barrier layer in an oxygen atmosphere are provided. The high frequency electrode is equipped with a lifting mechanism, and the σ2 chamber contains a DC magnetron sputtering target 202 for forming the Nb film, and a tray feeder 90.
- La 205 etc. are provided.

Using this apparatus, a superconducting tunnel junction was fabricated using Nb as the lower electrode, Nb oxide as the barrier layer, and Pbo, 9I nol as the upper electrode. This manufacturing process will be described below. A silicon wafer provided with a lower electrode Nb film for wiring is placed on the substrate tray L/I. The substrate tray was moved directly above the Nb sputtering target, and a Nb film was deposited to a thickness of 1 [10 nm] using a DC magnetron sputtering device. N
After forming the film, move the rear tray directly below the high-frequency target and lower the high-frequency electrode so that it comes into contact with the wafer tray and the wafer tray. In this state, 0□2 yol,
% -Ar gas was introduced and high frequency was applied to oxidize the Nb film surface layer. At this time, the gate pulp was closed. After the oxidation process was completed, vacuum evacuation was performed, the wafer tray was moved directly above the Nb and In evaporation sources, and PB and In were evaporated in this order. The concentration of In was set as a function of lQwt.

Thereafter, the substrate was taken out of the apparatus, and resist patterning and etching using an ion processing apparatus were performed to leave a portion corresponding to the tunnel junction. Next, an upper electrode film for wiring was formed to complete the superconducting tunnel junction device.

The local characteristics (critical Josephson current) of the junction devices manufactured by this method vary within ±10% within a 2-inch diameter wafer, and when 100 devices are arranged in series on a 5-mm-sized chip, The fluctuation of the junction element characteristics is also ±1
It was within 0%.

As described above, by using the manufacturing apparatus according to the invention in Bookcase 3, it is possible to continuously form a three-layer film of tunnel junction elements such as Nb-oxide-PbIn alloy, so that local variations in tunnel characteristics can be avoided. less (as critical Josephson current ±
(within 10%) can be obtained. Furthermore, since the high melting point metal film forming device, the barrier layer forming device, and the low melting point metal film forming device are installed in separate vacuum chambers, there is a risk of contamination of low melting point metal elements, oxygen, etc. into the high melting point metal film. It has the advantage of being pushed.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing a Josephson junction element Q produced by a conventional technique; FIGS. 5 is a plan view of a Josephson junction device according to an embodiment of the present invention, FIG. 6 is a sectional view of a superconducting junction device according to an embodiment of the second invention, FIGS. 7, 8, and 9. 10 is a sectional view showing the manufacturing process of a superconducting junction element in an embodiment of the second invention, and FIG. 10 is an explanatory diagram of a superconducting element manufacturing apparatus in an embodiment of the third invention. DESCRIPTION OF SYMBOLS 1... Si substrate, 2... Insulating layer, 3... Ground plane, 4... Insulating layer, 5... Lower wiring, 6...
・Nb film, 7... tunnel barrier layer, 8... Pb film,
9... Photoresist, 10... Insulating film, 11...
Upper wiring, 12... Josephson junction element, 110... Silicon wafer, 111... Nb ground plane film, 112... Interlayer insulating film, 113...
・Nb lower electrode film, 114...junction, 115...
Interlayer insulating film, 116... Pbo91no1 upper electrode film, 201... Pb or In evaporation boat, 20
2...DC magnetron target for Nb sputtering,
203...Substrate tray, 204...Gate pulp,
205... Roller for tray conveyance, 206... High frequency electrode. Fig. 1 Fig. 7 Hoshio 3 Rivers Fig. 4, II Fig. 5 Gen C Fig. 8 Fig. 9 Fig. 1 O Fig.

Claims (1)

[Scope of Claims] 1. A first electrode layer made of a superconductor and a second electrode layer made of a superconductor are bonded to each other via a tunnel barrier layer, the first electrode layer; The side surfaces of the second electrode layer and the tunnel barrier layer are approximately the same in the vertical direction.
Almost the entire lower surface of the eleventh electrode layer is in contact with the superconducting wiring layer 1, the nuclear superconducting wiring layer has a thickness greater than the magnetic field penetration distance of the superconducting material constituting it, and The total thickness of the first electrode layer, the tunnel barrier layer, and the second electrode layer is approximately one-tenth or less of the square root of the area of the junction. Josephson junction element. 2. Above - The three layers consisting of the first electrode layer, the tunnel barrier layer, and the second electrode layer are embedded in an insulating layer, and the upper surface of the second electrode layer and the upper surface of the insulating layer are The Josephson junction element according to claim 1, characterized in that no step is formed. 3. The Josephson junction device according to claim 2, wherein the insulating layer is made of SiO or SiO2. 4 The superconducting wiring layer and the first electrode layer are made of Nb.
Claims 1 and 2 are characterized in that:
Josephson junction element according to item 3 or item 3. 51) Step of forming a superconducting wiring layer on a substrate, if) forming a superconducting layer to be a first electrode layer, an insulating layer or a semiconductor layer to be a tunnel barrier layer, and a second 111) forming a three-layer core film with a superconducting layer that is to become an electrode layer to form a three-layer film; 111) molding the core three-layer film to form a joint in a predetermined shape at a predetermined position on the superconducting wiring layer; and iv) embedding the junction in an insulating layer approximately at the same height as the junction;
In addition, the thickness of the superconducting wiring layer is greater than or equal to the magnetic field penetration distance of the superconducting material constituting the superconducting wiring layer, and the thickness of the first electrode layer, the thickness of the tunnel barrier layer, and the thickness of the second electrode layer are The total thickness of approximately one-tenth of the square root of the area of the joint.
A method for manufacturing a Josephson junction element, characterized by the following: