JPH08321639A - Superconduction junction and formation of superconduction junction - Google Patents

Abstract

PURPOSE: To provide a superconduction junction, which has little 1/f noise, has a high superconducting critical temperature, is constituted of a superconducting thin film of high quality, is never deteriorated the quality even if the junction is processed into a circuit form, has a good current contact and has not a deteriorated layer on the interface between a high-resistance metal film and the junction. CONSTITUTION: A trench 101 is formed in a part directly over a crystal grain boundary part 2 in a bycrystal substrate 1 by a method, such as an etching method. Then, a superconducting thin film 3 is formed on this substrate. As the thin film 3 is generally formed into a hexagonal system and has a large anisotropy, the crystal c-axis of the film 3 is vertically grown to the substrate. As the growth rate of the film 3 is very high in the directions of the crystal a-axis and the crystal b-axis compared with the direction of the crystal c-axis, the thin film 3, which is grown on the surface of the substrate, is grown in the air even on the trench and overhangs are formed. When these fellow overhangs are linked with each other, a crystal grain boundary 102 is formed, whereby the crystal grain boundary is utilized as a superconduction junction.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a superconducting junction and a method for manufacturing the same, which are used for, for example, super high frequency detection and ultra small magnetic field detection.

[0002]

2. Description of the Related Art FIG. 8 shows, for example, Appl. Phys.
Lett. 63 (20), 2824, which is a schematic view of a conventional superconducting junction, 1 is a SrTiO ₃ bicrystal substrate, 2 is a junction portion of the bicrystal substrate,
3 is Ba _1-x K _x BiO ₃ thin film, 4 is Ba _1-x K _x BiO ₃
The grain boundary junction portion of the thin film, 5 is an Ag contact deposited on the Ba _1-x K _x BiO ₃ thin film 3, and 6 is an Ag paste for connecting the lead wire 7 to the Ag contact 5.

Next, the operation will be described. SrTiO ₃
A Ba _1-x K _x BiO ₃ thin film 3 is deposited on the bicrystal substrate 1 by a sputtering method, a laser ablation method or the like to form a film. Ba _1-x K _x BiO ₃ thin film 3 formed
Has the property of being formed in a form in which the crystal orientations are aligned according to the plane orientation of the bicrystal substrate 1. Therefore, on both sides of the junction portion 2 of the bicrystal substrate 1, thin films having different crystal orientations are formed. Therefore, this thin film B is formed so as to overlap directly on the junction 2 of the bicrystal substrate 1.
a _1-x K _x BiO ₃ thin film grain boundary junction 4 is provided.

The Ba _1-x K _x BiO ₃ thin film 3 is patterned into a circuit shape as shown in the figure by a method such as etching, and the grain boundary junction 4 is shaped so as to have a width of several μm to several hundred μm. And function as a superconducting junction.

[0005] In order to connect the current terminals to Ba _1-x K _x BiO ₃ thin film 3, the Ag paste 6 is deposited on the Ba _1-x K _x BiO ₃ thin film 3, the lead in the Ag paste 6 Connect line 7.

In the superconducting junction having such a structure, the grain boundary junction of the superconducting thin film acts as a superconducting weak bond and serves as a barrier for the quasi-particle current, resulting in non-linear current-voltage characteristics, and a barrier for the superconducting current. And cause the Josephson effect. Such an effect is utilized as a microwave mixer or a superconducting quantum interference device.

However, in the superconducting junction having such a structure, since the bicrystal substrate 1 is used as a substrate, the crystal grain boundary of the bicrystal portion of the bicrystal substrate 1 is greatly disturbed and formed on it. The crystal grain boundaries of the grain boundary junctions of the superconducting thin film were also greatly disturbed.
The disturbance of the crystal grain boundaries hinders the rapid flow of the magnetic flux penetrating the superconducting thin film, so that there is a problem that 1 / f noise is generated in the electric signal of the element using this junction.

As another conventional example, a grain boundary junction formed at the edge of a step of a superconducting thin film formed on a step by providing a step on the substrate without using a bicrystal substrate as a substrate is known. There is also a superconducting junction to use. FIG. 9 shows, for example, Japanese Journal of Ap.
FIG. 8 is a cross-sectional view showing a conventional superconducting junction described in plied Physics (30), 3907, and 3 and 4 are the same or corresponding portions as those of the conventional example, and
Is a crystal plane of the plane index (100) of the substrate, and 9 is a slope of a step provided on the substrate.

Next, the operation will be described. A MgO substrate having a crystal plane 8 with a surface index (100) has a step-like step formed by phosphoric acid etching, and YBaC is formed on the step.
The uO thin film 3 is deposited. At this time, discontinuous portions 4 of the YBaCuO thin film are formed on the upper and lower portions of the slope 9 of the step of the substrate. Since these discontinuous portions are grain boundaries of the superconducting thin film, these portions are shaped so as to have a width of several μm to several tens of μm so that they function as a superconducting junction.

However, in the superconducting junction having such a structure, since the upper and lower ends of the slope of the step of the substrate are gentle as shown in FIG. 9, many discontinuous portions 4 of the superconducting thin film are formed. Moreover, it occurs without regularity. The large number of such irregular grain boundaries impede the rapid flow of the magnetic flux through the superconducting thin film, so that the electrical signal of the device utilizing this junction is 1
There is a problem that / f noise is generated.

In addition, since the conventional superconducting junctions such as the above two examples use Ba _1-x K _x BiO ₃ as a superconducting thin film, the superconducting critical temperature is as low as about 20 K, and a refrigerator is used for actual device applications. It was not practical because the burden on the heat insulation system was large.

Further, since the lattice matching between SrTiO ₃ or MgO used for the substrate and Ba 1- _x K _x BiO ₃ of the superconducting thin film is poor, it is difficult to form a high-quality superconducting thin film. For example Ba1- _x K lattice constant of _x BiO ₃ is about 0.43 nm, the lattice constant of SrTiO ₃ is so about 0.39 nm, deposited on SrTiO ₃ B
The a _1-x K _x BiO ₃ film grows without matching with the lattice of the substrate and becomes a polycrystalline film having a random crystal orientation, which is an obstacle to formation of a good superconducting junction. Furthermore, the superconducting thin film deteriorates in the process of patterning the superconducting thin film into a circuit shape,
There is a problem that a good superconducting property cannot be obtained.

On the other hand, as a metal contact for connecting the superconducting thin film and the lead wire, a vapor-deposited thin film of Ag is used, but a chemical reaction occurs at the interface between them, and a good ohmic connection is made between the superconducting thin film and the metal contact. There was a problem that it was difficult to obtain.

In addition, when the superconducting junction is used as a microwave mixer, it is necessary to connect the superconducting thin film and the high resistance metal thin film. I was getting a physical connection.

FIG. 10 is a cross-sectional view showing a connection portion between such a conventional superconducting thin film and a high resistance metal thin film. In the figure, 1 to 3 are the same or corresponding portions as those of the conventional example, and 10 is a high portion. A resistive metal thin film, 11 is an interface-altered layer formed at the interface between the high temperature superconducting thin film 3 and the high resistance metallic thin film 10.

The interface between the superconducting thin film 3 and the high resistance metal thin film 10 shown in FIG. 10 exists at the junction between the superconducting thin film 3 and the high resistance metal thin film 10 of the superconducting junction thus formed. The interfacial alteration layer 11 is generated by the interaction between the substance forming the superconducting thin film 3 and the substance forming the high resistance metal thin film 10. This phenomenon remarkably appears when an oxide high temperature superconductor is used as a substance forming the superconducting thin film. The interface-altered layer 11 is unstable and easily decomposed, and the electric resistance is also unstable, which causes deterioration of the device characteristics.

[0017]

Since the conventional superconducting junction has been constructed as described above, it has the following problems. First, there is a problem in that the crystal grain boundaries of the bicrystal substrate are disturbed so that the superconducting junction is disturbed and 1 / f noise is generated. Similarly, depending on the method of providing the steps on the substrate, the steps are not sharp, so that the superconducting junction is disturbed and 1 / f noise is generated. Moreover, the superconducting critical temperature of the material of the superconducting thin film is as low as 10's K, and it is indispensable to use an expensive and large refrigerator or an expensive heat insulating material in order to maintain the superconducting state. In addition, the quality of the superconducting thin film was not good because the lattice constants of Ba _{1- x} K _x BiO _{3 of} the superconducting thin film and SrTiO ₃ of the substrate did not match. Further, there is a problem that the quality of the superconducting thin film is deteriorated at the stage of processing the superconducting thin film formed on the substrate into a circuit shape, which has been an obstacle when using the superconducting junction in a circuit. In addition, it is difficult to obtain a good ohmic connection between the superconducting thin film and the current contact, and on the other hand, there is a problem that an interface-altered layer is formed at the connecting portion between the superconducting thin film and the high resistance metal thin film.

The present invention has been made to solve the above-mentioned conventional problems, and is composed of a high-quality superconducting thin film having a low superconducting critical temperature and a low 1 / f noise.
Moreover, it is an object of the present invention to provide a superconducting junction that does not deteriorate in quality even when processed into a circuit shape, has a good current contact, and does not have an interface-altered layer with a high resistance metal, and a method for producing a superconducting junction.

[0019]

A superconducting junction according to the invention of claim 1 comprises a trench formed on a substrate and a superconducting thin film formed on the substrate, and the superconducting junction portion of the superconducting thin film is A superconducting junction formed in an overhang shape on the trench.

The superconducting junction according to the invention of claim 2 uses a bicrystal substrate as a substrate for forming a trench in the superconducting device of claim 1.

The superconducting junction according to the invention of claim 3 uses a single crystal substrate as a substrate for forming a trench in the superconducting junction of claim 1.

The superconducting junction according to the invention of claim 4 uses a SrTiO ₃ substrate as a substrate for forming a trench in the superconducting junction of claim 1.

The superconducting junction according to the invention of claim 5 uses a MgO substrate as a substrate for forming a trench in the superconducting junction of claim 1.

The superconducting junction according to the invention of claim 6 uses a sapphire (α-Al ₂ O ₃ ) substrate as a substrate for forming a trench in the superconducting junction of claim 1.

In the superconducting junction according to the invention of claim 7, a YSZ (yttrium-stabilized zirconia) substrate is used as a substrate for forming a trench in the superconducting junction of claim 1.

The superconducting junction according to the invention of claim 8 uses a CaTiO ₃ substrate as a substrate for forming a trench in the superconducting junction of claim 1.

The superconducting junction according to the invention of claim 9 uses a YAlO ₃ substrate as a substrate for forming a trench in the superconducting junction of claim 1.

The superconducting junction according to the invention of claim 10 uses an NdAlO ₃ substrate as a substrate for forming a trench in the superconducting junction of claim 1.

The superconducting junction according to the invention of claim 11 uses a LaAlO ₃ substrate as a substrate for forming a trench in the superconducting junction of claim 1.

The superconducting junction according to the twelfth aspect of the present invention uses a LaSrAlO ₄ substrate as a substrate for forming a trench in the superconducting junction of the first aspect.

The superconducting junction according to a thirteenth aspect of the invention uses an NdGaO ₃ substrate as a substrate for forming a trench in the superconducting junction of the first aspect.

The superconducting junction according to the fourteenth aspect of the present invention uses a PrGaO ₃ substrate as a substrate for forming a trench in the superconducting junction of the first aspect.

The superconducting junction according to the fifteenth aspect of the present invention uses a LaGaO ₃ substrate as a substrate for forming a trench in the superconducting junction of the first aspect.

A superconducting junction according to a sixteenth aspect of the present invention uses a LaSrGaO ₄ substrate as a substrate for forming a trench in the superconducting junction of the first aspect.

According to a seventeenth aspect of the present invention, there is provided a superconducting junction according to the first aspect, wherein the superconducting material is made of Ba1-.
_x K _x BiO ₃ is used.

The superconducting junction according to the eighteenth aspect of the present invention uses the bismuth-based superconducting oxide as the superconducting material in the superconducting junction of the first aspect.

The superconducting junction according to the invention of claim 19 uses the yttrium-based superconducting oxide as the superconducting material in the superconducting junction of claim 1.

A superconducting junction according to a twentieth aspect of the present invention is the superconducting junction according to the first aspect, in which a thallium-based superconducting oxide is used as the superconducting material.

The superconducting junction according to the twenty-first aspect of the present invention is the superconducting junction of the first aspect, wherein a mercury-based superconducting oxide is used as the superconducting material.

According to a twenty-second aspect of the present invention, there is provided a method of forming a superconducting junction, which comprises a step of forming a trench on a substrate and a step of forming a superconductor on the substrate so that the superconducting junction is formed on the trench. Be prepared.

The method of producing a superconducting junction according to the invention of claim 23 uses ion beam etching for producing a trench in the method of producing a superconducting junction of claim 22.

The method for producing a superconducting junction according to the twenty-fourth aspect uses reactive ion beam etching for producing a trench in the method for producing the superconducting junction according to the twenty-second aspect.

The method for producing a superconducting junction according to a twenty-fifth aspect of the present invention is that the reactive ion etching is used for producing a trench in the method for producing a superconducting junction according to the twenty-second aspect.

The method for producing a superconducting junction according to the twenty-sixth aspect of the present invention uses plasma etching for producing the trench in the method for producing the superconducting junction according to the twenty-second aspect.

In the method for producing a superconducting junction according to the twenty-seventh aspect of the present invention, wet etching is used for producing the trench in the method for producing the superconducting junction according to the twenty-second aspect.

In the method for producing a superconducting junction according to the invention of claim 28, the lift-off method is used for producing the trench in the method for producing a superconducting junction according to claim 22.

A superconducting junction according to a twenty-ninth aspect of the present invention comprises a step formed on a substrate and a superconducting thin film formed on the substrate, the superconducting thin film being formed on a step portion of the step. In the superconducting junction in which the part that functions as a Josephson junction, the plane-direction-dependent etching is used to fabricate the steps on the substrate.

The superconducting junction according to the thirtieth aspect of the present invention is KOH for manufacturing steps in the superconducting junction of the twenty-ninth aspect.
The surface orientation-dependent etching method using a solution containing is used.

The superconducting junction according to the thirty-first aspect of the present invention is the superconducting junction of the twenty-ninth aspect, wherein NaO is used for manufacturing steps.
The surface orientation-dependent etching method using a solution containing H is used.

According to a thirty-second aspect of the present invention, the superconducting junction according to the twenty-ninth aspect uses a plane orientation-dependent etching method using a solution containing hydrazine for producing steps.

A superconducting junction according to a thirty-third aspect of the present invention uses a plane-direction-dependent etching method using a solution containing ethylenediamine for producing steps in the superconducting junction of the twenty-ninth aspect.

According to a thirty-fourth aspect of the present invention, the superconducting junction according to the twenty-ninth aspect uses the plane orientation-dependent etching method using a solution containing a quaternary ammonium hydroxide for producing steps.

According to a thirty-fifth aspect of the present invention, in the superconducting junction of the twenty-ninth aspect, KOH is used for manufacturing steps.
And a plane orientation-dependent etching method using a solution containing 2-propanol.

The superconducting junction according to the thirty-sixth aspect of the present invention is the KOH for manufacturing steps in the superconducting junction of the twenty-ninth aspect.
And the azimuth dependent etching method using a solution containing hydrazine.

The superconducting junction according to the thirty-seventh aspect of the present invention is that the step of the superconducting junction of the twenty-ninth aspect is performed by using a both-side dependent etching method using a solution containing hydrazine and H ₂ O.

The superconducting junction according to the thirty-eighth aspect of the present invention uses the plane-orientation-dependent etching method using a solution containing methylammonium hydroxide for producing steps in the superconducting junction of the twenty-ninth aspect.

According to the 39th aspect of the present invention, there is provided a superconducting junction according to the 29th aspect, wherein NH4 is used for manufacturing steps.
The plane orientation dependent etching method using a solution containing F and Cu (NO ₃ ) ₂ is used.

A superconducting junction according to the invention of claim 40 is a superconducting junction constituted by a substrate, a superconducting thin film formed on the substrate, and a superconducting junction portion of the superconducting thin film, wherein the superconducting thin film is epitaxially formed on the superconducting thin film. A superconducting junction having a protective film formed.

The superconducting junction according to the invention of claim 41 is the superconducting thin film according to claim 40, wherein Ba is used as the superconducting thin film.
The _1-x K _x BiO _3, is to use BaBiO ₃ as a protective film.

The superconducting junction according to a forty-second aspect of the present invention is the superconducting junction of the fortieth aspect, wherein the superconducting thin film is made of Ba.
The _1-x K _x BiO _3, is to use BaPbO ₃ as a protective film.

A superconducting junction according to the invention of claim 43 is a superconducting junction comprising a substrate, a superconducting thin film formed on the substrate, and a superconducting joint portion of the superconducting thin film, wherein the substrate and the superconducting thin film are In between, the superconducting thin film has a buffer layer which can be formed epitaxially.

The superconducting junction according to the invention of claim 44 is the superconducting junction according to claim 43, wherein Ba is used as the superconducting thin film.
The _1-x K _x BiO _3, is to use BaBiO ₃ as the buffer layer.

The superconducting junction according to the 45th aspect of the present invention is the superconducting junction according to the 43rd aspect, wherein Ba is used as the superconducting thin film.
The _1-x K _x BiO _3, is to use BaPbO ₃ as the buffer layer.

The superconducting junction according to the 46th aspect of the present invention is the superconducting junction according to the 43rd aspect, wherein Ba is used as the superconducting thin film.
The _1-x K _x BiO _3, a MgO as the buffer layer, is to use a sapphire substrate.

The superconducting junction according to the 47th aspect of the present invention is a superconducting junction comprising a superconducting thin film, a superconducting junction part of the superconducting thin film, and an electrode formed on the superconducting thin film, wherein an oxide thin film is used as the electrode. Is used.

The superconducting junction according to the 48th aspect of the present invention is a superconducting junction composed of a superconducting thin film, a superconducting junction part of the superconducting thin film, and an electrode formed on the superconducting thin film. Is used to form the electrode in-situ after forming the superconducting thin film.

The superconducting junction according to the 49th aspect of the present invention is the superconducting junction according to the 47th aspect, wherein Ba is used as the superconducting thin film.
The _1-x K _x BiO _3, is to use NbO as an electrode.

The superconducting junction according to the 50th aspect of the present invention is the superconducting junction according to the 47th aspect, wherein Ba is used as the superconducting thin film.
The _1-x K _x BiO _3, is to use NdO as an electrode.

The superconducting junction according to the invention of claim 51 is the superconducting junction of claim 47 wherein Ba is used as the superconducting thin film.
The _1-x K _x BiO _3, is to use a ReO ₃ as an electrode.

The superconducting junction according to the 52nd aspect of the present invention is the superconducting junction according to the 47th aspect, wherein Ba is used as the superconducting thin film.
The _1-x K _x BiO _3, is to use the RuO ₂ as an electrode.

The superconducting junction according to the invention of claim 53 is the superconducting junction of claim 47 wherein Ba is used as the superconducting thin film.
The _1-x K _x BiO _3, is to use OsO ₂ as electrodes.

The superconducting junction according to the invention of claim 54 is the superconducting junction of claim 47, wherein the superconducting thin film is made of Ba.
The _1-x K _x BiO _3, is to use the IrO ₂ as electrodes.

The superconducting junction according to the 55th aspect of the present invention is a superconducting junction comprising a superconducting thin film and a superconducting junction part of the superconducting thin film, wherein a Bi-based superconductor is used as the superconducting thin film, and a composition ratio of a part thereof is used. To be an insulator, and a region sandwiching this insulator portion is used as a superconducting junction.

The superconducting junction according to the 56th aspect of the present invention is the superconducting junction according to the 55th aspect, wherein BiS is used as the superconducting thin film.
r (Ca, Y) CuO is used, and a composition with an excess of Y is used as a part thereof to form an insulator, and a region sandwiching this insulator part is used as a superconducting junction.

The superconducting junction according to the 57th aspect of the present invention is the superconducting junction according to the 55th aspect, wherein BiS is used as the superconducting thin film.
rCa (Cu, Fe) O is used, and a composition containing excess Fe is used as an insulator to form an insulator, and a region sandwiching the insulator is used as a superconducting junction.

The superconducting junction according to the invention of claim 58 is a superconducting junction comprising a superconducting thin film and a superconducting junction portion of the superconducting thin film, wherein the superconducting thin film has the resistor thin film connected to the superconducting thin film. A resistor thin film is arranged without overlapping, and the superconducting thin film and the resistor thin film are connected by a low resistance metal thin film.

According to a 59th aspect of the present invention, there is provided a superconducting junction according to the 58th aspect, wherein the superconducting thin film is made of Ba as a superconducting thin film.
The _1-x K _x BiO _3, a TaN as a resistance thin film is to use Au as a low-resistance metal film.

A superconducting junction according to the invention of claim 60 is the superconducting junction of claim 58, wherein the superconducting thin film is used as a microwave strip line and the resistor thin film is used as a terminator of the strip line.

[0079]

A superconducting junction according to the invention of claim 1 comprises a trench formed on a substrate and a superconducting thin film formed on the substrate, and a superconducting junction portion of the superconducting thin film overhangs on the trench. Since the crystal grain boundaries that form the superconducting junction do not contact the substrate when formed in a uniform shape, the flow of magnetic flux at the crystal grain boundaries is not affected by the disturbance of the crystal grain boundaries of the substrate and is not disturbed. Will be things.

In the superconducting junction according to the invention of claim 2, the trench is formed on the bicrystal substrate, and the superconducting thin film is provided on the bicrystal substrate, so that the superconducting junction portion of the superconducting thin film overhangs the trench. Since the crystal grain boundaries that form the superconducting junction do not contact the substrate, the flow of magnetic flux at the crystal grain boundaries is not affected by the disturbance of the crystal grain boundaries of the substrate, and it is assumed that there is no disturbance. Become.

In the superconducting junction according to the third aspect of the present invention, the trench is formed on the single crystal substrate and the superconducting thin film is provided on the bicrystal substrate, so that the superconducting junction portion of the superconducting thin film overhangs the trench. Since the crystal grain boundaries that form the superconducting junction do not contact the substrate, the flow of magnetic flux at the crystal grain boundaries is not affected by the disturbance of the crystal grain boundaries of the substrate, and it is assumed that there is no disturbance. Become.

The superconducting junction according to the invention of claim 4 is S
By forming the trench on the rTiO ₃ substrate and providing the superconducting thin film on the bicrystal substrate, the superconducting junction part of the superconducting thin film is formed in the overhang shape on the trench, so that the grain boundary forms the superconducting junction. Does not come into contact with the substrate, the flow of magnetic flux at the crystal grain boundaries is smooth and undisturbed without being affected by the disorder of the crystal grain boundaries of the substrate.

The superconducting junction according to the invention of claim 5 is M
Since the trench is formed on the gO substrate and the superconducting thin film is provided on the bicrystal substrate, the superconducting junction portion of the superconducting thin film is formed in the overhang shape on the trench, so that the grain boundaries forming the superconducting junction are Since there is no contact with the substrate, the flow of magnetic flux at the crystal grain boundaries is smooth and undisturbed without being affected by the disorder of the crystal grain boundaries of the substrate.

In the superconducting junction according to the invention of claim 6, the trench is formed on the sapphire (α-Al ₂ O ₃ ) substrate, and the superconducting thin film is provided on the bicrystal substrate. Since the crystal grain boundaries that form the superconducting junction are not in contact with the substrate due to the overhang formation on the trench, the flow of magnetic flux at the crystal grain boundaries is not affected by the disorder of the crystal grain boundaries of the substrate. It will be smooth and undisturbed.

The superconducting junction according to the invention of claim 7 is Y
Since the superconducting thin film is provided on the SZ (yttrium-stabilized zirconia) substrate, the superconducting junction portion of the superconducting thin film is formed overhanging on the trench, so that the crystal grain boundary forming the superconducting junction may contact the substrate. Since it does not exist, the flow of magnetic flux at the crystal grain boundaries is not affected by the turbulence of the crystal grain boundaries of the substrate and becomes smooth and turbulent.

The superconducting junction according to the invention of claim 8 is C
Since the superconducting thin film is provided on the aTiO ₃ substrate, the superconducting junction portion of the superconducting thin film is formed overhanging on the trench, so that the crystal grain boundary forming the superconducting junction does not contact the substrate. The flow of magnetic flux in the field is smooth and undisturbed without being affected by the disorder of the crystal grain boundaries of the substrate.

The superconducting junction according to the invention of claim 9 is Y
By providing the superconducting thin film on the AlO ₃ substrate, the superconducting junction part of the superconducting thin film is formed overhanging on the trench, so that the crystal grain boundary forming the superconducting junction does not contact the substrate. The flow of magnetic flux in the field is smooth and undisturbed without being affected by the disorder of the crystal grain boundaries of the substrate.

The superconducting junction according to the invention of claim 10 is
Since the superconducting thin film is provided on the NdAlO ₃ substrate, the superconducting junction portion of the superconducting thin film is formed overhanging on the trench, so that the crystal grain boundary forming the superconducting junction does not contact the substrate. The flow of magnetic flux in the field is smooth and undisturbed without being affected by the disorder of the crystal grain boundaries of the substrate.

The superconducting junction according to the invention of claim 11 is
Since the superconducting thin film is provided on the LaAlO ₃ substrate, the superconducting junction part of the superconducting thin film is formed overhanging on the trench, so that the crystal grain boundary forming the superconducting junction does not contact the substrate. The flow of magnetic flux in the field is smooth and undisturbed without being affected by the disorder of the crystal grain boundaries of the substrate.

The superconducting junction according to the invention of claim 12 is
By providing the superconducting thin film on the LaSrAlO ₄ substrate, the superconducting junction part of the superconducting thin film is formed overhanging on the trench, so that the crystal grain boundary forming the superconducting junction does not contact the substrate. The flow of magnetic flux in the field is smooth and undisturbed without being affected by the disorder of the crystal grain boundaries of the substrate.

The superconducting junction according to the invention of claim 13 is
Since the superconducting thin film is provided on the NdGaO ₃ substrate, the superconducting junction part of the superconducting thin film is formed overhanging on the trench, so that the crystal grain boundary forming the superconducting junction does not contact the substrate. The flow of magnetic flux in the field is smooth and undisturbed without being affected by the disorder of the crystal grain boundaries of the substrate.

The superconducting junction according to the invention of claim 14 is
Since the superconducting thin film is provided on the PrGaO ₃ substrate, the superconducting junction part of the superconducting thin film is formed overhanging on the trench, so that the crystal grain boundary forming the superconducting junction does not contact the substrate. The flow of magnetic flux in the field is smooth and undisturbed without being affected by the disorder of the crystal grain boundaries of the substrate.

The superconducting junction according to the invention of claim 15 is
Since the superconducting thin film is provided on the LaGaO ₃ substrate, the superconducting junction part of the superconducting thin film is formed overhanging on the trench, so that the crystal grain boundary forming the superconducting junction does not contact the substrate. The flow of magnetic flux in the field is smooth and undisturbed without being affected by the disorder of the crystal grain boundaries of the substrate.

The superconducting junction according to the sixteenth aspect of the invention is
By providing the superconducting thin film on the LaSrGaO ₄ substrate, the superconducting junction part of the superconducting thin film is formed overhanging on the trench, so that the crystal grain boundary forming the superconducting junction does not contact the substrate. The flow of magnetic flux in the field is smooth and undisturbed without being affected by the disorder of the crystal grain boundaries of the substrate.

The superconducting junction according to the seventeenth aspect of the invention is
A trench formed on a substrate, and a superconducting thin film of a Ba _{1 -x} K _x BiO ₃ superconducting material formed on the substrate,
Since the superconducting junction portion of the superconducting thin film is formed in an overhang shape on the trench, the crystal grain boundary forming the superconducting junction does not contact the substrate. It is smooth and undisturbed without being affected by the disturbance of grain boundaries.

The superconducting junction according to the invention of claim 18 is
A trench formed on a substrate, and a superconducting thin film of a bismuth-based superconducting oxide superconducting material formed on the substrate, wherein the superconducting junction of the superconducting thin film is formed in an overhang shape on the trench. Since the crystal grain boundaries forming the superconducting junction do not contact the substrate, the flow of magnetic flux at the crystal grain boundaries is smooth and undisturbed without being affected by the disorder of the crystal grain boundaries of the substrate.

The superconducting junction according to the nineteenth aspect of the invention is
A trench formed on a substrate and a superconducting thin film of a yttrium-based superconducting oxide superconducting material formed on the substrate are provided, and a superconducting junction portion of the superconducting thin film is formed in an overhang shape on the trench. Since the crystal grain boundaries forming the superconducting junction do not contact the substrate, the flow of magnetic flux at the crystal grain boundaries is smooth and undisturbed without being affected by the disorder of the crystal grain boundaries of the substrate.

The superconducting junction according to the invention of claim 20 is
A trench prepared on a substrate and a superconducting thin film of a thallium-based superconducting oxide superconducting material formed on the substrate are provided, and a superconducting junction portion of the superconducting thin film is formed in an overhang shape on the trench. Since the crystal grain boundaries forming the superconducting junction do not contact the substrate, the flow of magnetic flux at the crystal grain boundaries is smooth and undisturbed without being affected by the disorder of the crystal grain boundaries of the substrate.

The superconducting junction according to the invention of claim 21 is
A trench formed on the substrate, and a superconducting thin film of a mercury-based superconducting oxide superconducting material formed on the substrate,
Since the superconducting junction portion of the superconducting thin film is formed in an overhang shape on the trench, the crystal grain boundary forming the superconducting junction does not contact the substrate. It is smooth and undisturbed without being affected by the disturbance of grain boundaries.

The method for forming a superconducting junction according to the twenty-second aspect of the present invention comprises a step of forming a trench on a substrate and a step of forming a superconducting film on the substrate so that the superconducting junction is formed on the trench. With the provision, the superconducting junction portion of the superconducting thin film is formed in an overhang shape on the trench so that the crystal grain boundary forming the superconducting junction does not contact the substrate.

The method for producing a superconducting junction according to the twenty-third aspect of the present invention is the step of producing a trench on a substrate by using ion beam etching, and the superconducting film is formed so that the superconducting junction is formed on the trench. By providing the step of producing on the substrate, the superconducting junction part of the superconducting thin film is formed overhanging on the trench and the crystal grain boundary forming the superconducting junction does not contact the substrate.

According to a twenty-fourth aspect of the present invention, there is provided a method of forming a superconducting junction, which comprises a step of forming a trench on a substrate by using reactive ion beam etching, and a superconducting film so that the superconducting junction is formed on the trench. By providing the step of forming the superconducting thin film on the substrate, the superconducting junction part of the superconducting thin film is formed overhanging on the trench and the crystal grain boundary forming the superconducting junction does not contact the substrate.

The method of forming a superconducting junction according to the twenty-fifth aspect of the present invention is a step of forming a trench on a substrate by using reactive ion etching, and forming a superconducting film so that the superconducting junction is formed on the trench. By including the step of manufacturing on the substrate, the superconducting junction part of the superconducting thin film is formed in an overhang shape on the trench so that the crystal grain boundary forming the superconducting junction does not contact the substrate.

According to a twenty-sixth aspect of the present invention, there is provided a method of forming a superconducting junction, the method comprising: forming a trench on a substrate by using plasma etching; and forming a superconducting film on the substrate so that the superconducting junction is formed on the trench. By providing the above-described process, the superconducting junction portion of the superconducting thin film is formed overhanging on the trench so that the crystal grain boundaries forming the superconducting junction do not contact the substrate.

According to a twenty-seventh aspect of the present invention, there is provided a method of forming a superconducting junction, the method comprising: forming a trench on a substrate by wet etching; and forming a superconducting film on the substrate so that the superconducting junction is formed on the trench. By providing the above-described process, the superconducting junction portion of the superconducting thin film is formed overhanging on the trench so that the crystal grain boundaries forming the superconducting junction do not contact the substrate.

According to a twenty-eighth aspect of the present invention, there is provided a method of forming a superconducting junction, the step of forming a trench on a substrate by a lift-off method, and the superconducting film on the substrate so that the superconducting junction is formed on the trench. By providing the above-described process, the superconducting junction portion of the superconducting thin film is formed overhanging on the trench so that the crystal grain boundaries forming the superconducting junction do not contact the substrate.

The superconducting junction according to the invention of claim 29 is:
Since the sharp grain boundary junction formed on the sharp step formed on the substrate by the plane orientation dependent etching can be used as the Josephson junction, 1 / f noise of the signal flowing through the junction is greatly reduced.

The superconducting junction according to the invention of claim 30 is
The sharp grain boundary junction formed on the sharp step formed by the plane orientation dependent etching with the solution containing KOH on the substrate can be used as the Josephson junction, so that 1 / f noise of the signal flowing through the junction is reduced. Greatly reduced.

The superconducting junction according to the invention of claim 31 is
The sharp grain boundary junction formed on the sharp step formed by the plane-direction dependent etching with the solution containing NaOH on the substrate can be used as the Josephson junction, so that 1 / f noise of the signal flowing through the junction is reduced. Greatly reduced.

The superconducting junction according to the invention of claim 32 is
The sharp grain boundary junction formed on the sharp step formed by the plane orientation dependent etching with the solution containing hydrazine on the substrate can be used as the Josephson junction, so that 1 / f noise of the signal flowing through the junction is reduced. Greatly reduced.

The superconducting junction according to the invention of claim 33 is
A sharp grain boundary junction formed on a sharp step formed by plane-direction dependent etching with a solution containing ethylediamine on the substrate can be used as a Josephson junction, so that 1 / f noise of a signal flowing through the junction is reduced. Greatly reduced.

The superconducting junction according to the invention of claim 34 is
The sharp grain boundary junction formed on the sharp step created by the plane orientation dependent etching with the solution containing quaternary ammonium hydroxide on the substrate can be used as a Josephson junction, so that the signal flowing through the junction is 1 /
f-noise is greatly reduced.

The superconducting junction according to the invention of claim 35 is
The sharp grain boundary junction formed on the sharp step formed by the plane orientation dependent etching with the solution containing KOH and 2-propanol on the substrate can be used as the Josephson junction, so that the signal flowing through the junction is /
f-noise is greatly reduced.

The superconducting junction according to the thirty-sixth aspect of the present invention is
The sharp grain boundary junction formed on the sharp step formed by the plane-orientation-dependent etching with the solution containing KOH and humanradin on the substrate can be used as the Josephson junction, so 1 / f of the signal flowing through the junction The noise is greatly reduced.

The superconducting junction according to the invention of claim 37 is
The sharp grain boundary junction formed on the sharp step formed by the plane orientation dependent etching with the solution containing humanradine and H ₂ O on the substrate can be used as the Josephson junction, so that the signal flowing through the junction is / F noise is greatly reduced.

The superconducting junction according to the thirty-eighth aspect of the invention is
Since a sharp grain boundary junction formed on a sharp step formed by plane-direction dependent etching with a solution containing methylammonium hydroxide on the substrate can be used as a Josephson junction
/ F noise is greatly reduced.

A superconducting junction according to the invention of claim 39 is
Since the sharp grain boundary junction formed on the sharp step formed by the plane orientation dependent etching with the solution containing NH ₄ F and Cu (NO ₃ ) ₂ on the substrate can be used as the Josephson junction, the junction 1 of the signal flowing through
f-noise is greatly reduced.

The superconducting junction according to the invention of claim 40 is
In a superconducting junction composed of a substrate, a superconducting thin film formed on the substrate, and a superconducting junction part of the superconducting thin film, a superconducting thin film forming a superconducting junction by having a protective film epitaxially formed on the superconducting thin film. Since the superconducting thin film can be protected without adversely affecting the surface of the superconducting film, the superconducting thin film is used as a photoresist for photoengraving during the process of processing the superconducting junction into a circuit shape, or as an organic material such as acetone when removing the photoresist. Since it is not exposed to a solvent, it is possible to prevent deterioration of superconducting characteristics during the process of processing the superconducting junction into a circuit shape.

The superconducting junction according to the invention of claim 41 is
In a superconducting junction composed of a substrate, a superconducting thin film of Ba _{1- x} K _x BiO ₃ formed on the substrate, and a superconducting junction part of the superconducting thin film, a protective film of BaBiO ₃ epitaxially formed on the superconducting thin film. By having, it is possible to protect the superconducting thin film without adversely affecting the superconducting thin film forming the superconducting junction, such as distortion, so in the process of processing the superconducting junction into a circuit shape, the superconducting thin film is a photoresist for photolithography. Since it is not exposed to an organic solvent such as acetone when removing the photoresist and the photoresist, it is possible to prevent deterioration of the superconducting characteristics during the process of processing the superconducting junction into a circuit shape.

The superconducting junction according to the invention of claim 42 is
In a superconducting junction composed of a substrate, a superconducting thin film of Ba _{1- x} K _x BiO ₃ formed on the substrate, and a superconducting junction part of the superconducting thin film, a protective film of BaPbO ₃ epitaxially formed on the superconducting thin film. By having, it is possible to protect the superconducting thin film without adversely affecting the superconducting thin film forming the superconducting junction, such as distortion, so in the process of processing the superconducting junction into a circuit shape, the superconducting thin film is a photoresist for photolithography. Since it is not exposed to an organic solvent such as acetone when removing the photoresist and the photoresist, it is possible to prevent deterioration of the superconducting characteristics during the process of processing the superconducting junction into a circuit shape.

A superconducting junction according to the invention of claim 43 is
Substrate, a superconducting thin film formed on the substrate, in a superconducting junction constituted by the superconducting junction portion of the superconducting thin film, between the substrate and the superconducting thin film, by having a buffer layer that can be epitaxially formed superconducting thin film, Since the superconducting thin film can be formed with high quality without being affected by the lattice mismatch with the substrate, the characteristics of the superconducting junction are improved.

The superconducting junction according to the invention of claim 44 is
In a superconducting junction composed of a substrate, a superconducting thin film formed on the substrate, and a superconducting junction part of the superconducting thin film, a superconducting thin film of Ba _1-x K _x BiO ₃ is epitaxially formed between the substrate and the superconducting thin film. BaBi that can be formed
By having the O ₃ buffer layer, the superconducting thin film can be formed with high quality without being affected by the lattice mismatch with the substrate, so that the characteristics of the superconducting junction are improved.

The superconducting junction according to the 45th aspect of the invention is
In a superconducting junction composed of a substrate, a superconducting thin film formed on the substrate, and a superconducting junction part of the superconducting thin film, a superconducting thin film of Ba _1-x K _x BiO ₃ is epitaxially formed between the substrate and the superconducting thin film. BaBa that can be formed
By having the PbO ₃ buffer layer, the superconducting thin film can be formed with high quality without being affected by the lattice mismatch with the substrate, so that the characteristics of the superconducting junction are improved.

The superconducting junction according to the 46th aspect of the invention is
In a superconducting junction composed of a substrate using sapphire, a superconducting thin film formed on the substrate, and a superconducting junction part of the superconducting thin film, B
Since the superconducting thin film made of a _1-x K _x BiO ₃ has the MgO ₃ buffer layer that can be epitaxially formed, the superconducting thin film can be formed with high quality without being affected by the lattice mismatch with the substrate. The characteristics of are improved.

The superconducting junction according to the 47th aspect of the invention is
A superconducting thin film, a superconducting junction part of the superconducting thin film, and a superconducting junction composed of an electrode deposited on the superconducting thin film, by using an oxide thin film as an electrode,
Since the material of the electrode deposited on the superconducting thin film is not a metal but a conductive oxide, it is possible to suppress the generation of a deteriorated layer especially at the interface between the superconducting thin film using an oxide superconductor and the electrode. Therefore, good ohmic connection can be obtained between the superconducting thin film and the electrode.

The superconducting junction according to the 48th aspect of the invention is
In a superconducting junction composed of a superconducting thin film, a superconducting junction part of the superconducting thin film, and an electrode deposited on the superconducting thin film, an oxide thin film is used as an electrode, and the electrode is formed on the spot after forming the superconducting thin film. I decided to do so,
Since it becomes possible to suppress the generation of an altered layer at the interface between the superconducting thin film using an oxide superconductor and the electrode, a good ohmic connection can be obtained between the superconducting thin film and the electrode.

The superconducting junction according to the 49th aspect of the invention is
In a superconducting junction composed of a superconducting thin film, a superconducting junction part of the superconducting thin film, and an electrode deposited on the superconducting thin film, by using an NbO oxide thin film as an electrode, Ba _1-x K _x BiO ₃ Since the material of the electrode deposited on the superconducting thin film is not a metal but a conductive oxide, it is possible to suppress the generation of an altered layer especially at the interface between the superconducting thin film and the electrode using an oxide superconductor. Therefore, good ohmic connection can be obtained between the superconducting thin film and the electrode.

The superconducting junction according to the invention of claim 50 is
In a superconducting junction composed of a superconducting thin film, a superconducting junction part of the superconducting thin film, and an electrode deposited on the superconducting thin film, by using an NdO oxide thin film as an electrode, Ba _1-x K _x BiO ₃ Since the material of the electrode deposited on the superconducting thin film is not a metal but a conductive oxide, it is possible to suppress the generation of an altered layer especially at the interface between the superconducting thin film and the electrode using an oxide superconductor. Therefore, good ohmic connection can be obtained between the superconducting thin film and the electrode.

The superconducting junction according to the invention of claim 51 is
In a superconducting junction composed of a superconducting thin film, a superconducting junction part of the superconducting thin film, and an electrode deposited on the superconducting thin film, by using an oxide thin film of ReO ₃ as an electrode, Ba _1-x K _x BiO ₃ Since the material of the electrode deposited on the superconducting thin film of is a conductive oxide instead of a metal, it is possible to suppress the generation of a deteriorated layer particularly at the interface between the superconducting thin film using an oxide superconductor and the electrode. As a result, a good ohmic connection can be obtained between the superconducting thin film and the electrode.

A superconducting junction according to the invention of claim 52 is
In a superconducting junction composed of a superconducting thin film, a superconducting junction part of the superconducting thin film, and an electrode deposited on the superconducting thin film, by using an oxide thin film of RuO ₂ as an electrode, Ba _1-x K _x BiO ₃ Since the material of the electrode deposited on the superconducting thin film of is a conductive oxide instead of a metal, it is possible to suppress the generation of a deteriorated layer particularly at the interface between the superconducting thin film using an oxide superconductor and the electrode. As a result, a good ohmic connection can be obtained between the superconducting thin film and the electrode.

The superconducting junction according to the invention of claim 53 is
By using an oxide thin film of OsO ₂ as an electrode in a superconducting junction composed of a superconducting thin film, a superconducting junction part of the superconducting thin film, and an electrode deposited on the superconducting thin film, Ba _1-x K _x BiO ₃ Since the material of the electrode deposited on the superconducting thin film of is a conductive oxide instead of a metal, it is possible to suppress the generation of a deteriorated layer particularly at the interface between the superconducting thin film using an oxide superconductor and the electrode. As a result, a good ohmic connection can be obtained between the superconducting thin film and the electrode.

The superconducting junction according to the invention of claim 54 is:
By using an IrO ₂ oxide thin film as an electrode in a superconducting junction composed of a superconducting thin film, a superconducting junction of the superconducting thin film, and an electrode deposited on the superconducting thin film, Ba _1-x K _x BiO ₃ Since the material of the electrode deposited on the superconducting thin film of is a conductive oxide instead of a metal, it is possible to suppress the generation of a deteriorated layer particularly at the interface between the superconducting thin film using an oxide superconductor and the electrode. As a result, a good ohmic connection can be obtained between the superconducting thin film and the electrode.

The superconducting junction according to the 55th aspect of the invention is
In a superconducting junction composed of a superconducting thin film and a superconducting junction part of the superconducting thin film, a Bi-based superconductor is used as the superconducting thin film, and an insulator is formed by changing the composition ratio of a part of the superconducting thin film. By using the region as a superconducting junction, the load on the cooling system can be reduced by raising the operating temperature.

The superconducting junction according to the 56th aspect of the invention is
In the superconducting junction composed of the superconducting thin film and the superconducting junction of the superconducting thin film, BiSr is used as the superconducting thin film.
(Ca, Y) CuO is used as an insulator by using a composition with an excess of Y in a part thereof, and the region sandwiching this insulator part is used as a superconducting junction, so that the cooling system can be increased by increasing the operating temperature. Burden is reduced.

The superconducting junction according to the 57th aspect of the invention is
BiSrC as a superconducting thin film in a superconducting junction composed of a superconducting thin film and a superconducting junction of the superconducting thin film.
a (Cu, Fe) O is used as an insulator by using a composition with an excess of Fe in a part thereof, and a region sandwiching this insulator part is used as a superconducting junction. Since the body is used, the operating temperature of the superconducting junction can be increased and the burden on the cooling system can be greatly reduced.

The superconducting junction according to the invention of claim 58 is
In a superconducting junction having a superconducting thin film and a superconducting junction part of the superconducting thin film and having a resistor thin film connected to the superconducting thin film, the superconducting thin film and the resistor thin film are arranged without overlapping, and the superconducting thin film and the resistor The thin film is connected by a low resistance metal thin film.Since the superconducting thin film and the high resistance metal thin film are not placed on top of each other, no deterioration layer will occur at the interface between them and prevent deterioration of the device characteristics. be able to.

The superconducting junction according to the 59th aspect of the invention is
In a superconducting junction having a superconducting thin film and a resistor thin film connected to the superconducting thin film, the superconducting thin film of Ba _1-x K _x BiO _{3 and} the superconducting thin film
The aN resistor thin film is arranged without overlapping, and the superconducting thin film and the resistor thin film are connected by a low resistance Au metal thin film. Since the superconducting thin film and the high resistance metal thin film are not arranged on top of each other, they are A deteriorated layer does not occur at the interface between them, and deterioration of the device characteristics can be prevented.

The superconducting junction according to the invention of claim 60 is
In a superconducting junction that has a superconducting thin film and a superconducting junction part of the superconducting thin film and has a resistor thin film connected to the superconducting thin film, using the superconducting thin film and the resistor thin film by the microwave strip line as the strip line terminator By arranging without superposition, by arranging a low resistance metal thin film that overlaps both the superconducting thin film and the resistor thin film, the superconducting thin film and the high resistance metal thin film are not placed on top of each other, so the interface between them A deteriorated layer does not occur in the device and deterioration of the device characteristics can be prevented.

[0139]

【Example】

Example 1. Hereinafter, this embodiment will be described. FIG. 1 is a sectional view of a superconducting junction showing the present embodiment.
Numbers 1 to 3 are the same as or corresponding to those in the conventional example, 101 is a trench formed on the grain boundary 2 of the substrate 1, and 102 is a superconducting thin film junction formed on the trench 101. It is a department.

Next, the operation will be described. A trench 101 is formed directly above the crystal grain boundary portion 2 of the bicrystal substrate 1 by a method such as etching. Next, the superconducting thin film 3 is formed on this substrate. Generally, the superconducting thin film has a hexagonal crystal system and has a large anisotropy. Normal crystal c
The axis grows perpendicular to the substrate. The growth rate is much higher in the a-axis and b-axis directions than in the c-axis direction. Therefore, the superconducting thin film 3 growing on the surface of the substrate also grows hollow on the trench and forms an overhang. When these overhangs are connected to each other, a crystal grain boundary 102 is formed. The crystal grain boundary thus produced is used as a superconducting junction.

In this example, a SrTiO ₃ bicrystal substrate (10 mm × 10 mm × 1 mm) was used as a substrate, and a trench having a width of 1 μm and a depth of 5 μm was formed by an ion beam etching method using Ar ions. When Ba _1-x K _x BiO ₃ was deposited on the substrate by RF magnetron sputtering to a thickness of 200 nm, Ba _1-x K _x BiO ₃ was grown so as to close the trench, and grain boundaries were formed on the trench. A bond was formed. The Ba _1-x K _x BiO ₃ thin film including this grain boundary junction was formed into a bridge shape having a width of 20 μm by reactive etching with ethane gas. When this element was cooled in liquid helium and 1 / f noise was measured from the Fourier transform of the current-voltage characteristic, 1.7 × 1
It was 0 ^-5 Φ ₀ / Hz ^-2 . The 1 / f noise of the element manufactured by the method of the conventional example was 1.4 × 10 ⁻⁴ Φ ₀ / Hz ⁻² , so that a significant reduction of 1 / f noise was achieved.

Example 2. Although the bicrystal substrate is used as the substrate 1 in Example 1, the same effect can be obtained by using a normal single crystal substrate as the substrate. Also in this case, although there is no in-plane rotation of the crystal orientation, the superconducting junction is formed on the trench by reflecting the deviation of the lattice matching between the substrate and the superconducting thin film.

Example 3. In Example 1, Sr was used as the substrate 1.
Although a TiO ₃ bicrystal substrate is used, the material of the substrate is not limited to SrTiO ₃ and the same effect can be obtained by using a MgO substrate.

Example 4. In Example 1, Sr was used as the substrate 1.
Although a TiO ₃ bicrystal substrate is used, the material of the substrate is not limited to SrTiO _3, and the same effect can be obtained by using a sapphire (α-Al ₂ O ₃ ) substrate.

Example 5. In Example 1, Sr was used as the substrate 1.
Although a TiO ₃ bicrystal substrate is used, the material of the substrate is not limited to SrTiO _3, and the same effect can be obtained by using a YSZ (yttrium-stabilized zirconia) substrate.

Example 6. In Example 1, Sr was used as the substrate 1.
Although a TiO ₃ bicrystal substrate was used, the material of the substrate is not limited to SrTiO ₃ and CaTiO ₃
The same effect can be obtained by using a substrate.

Example 7. In Example 1, Sr was used as the substrate 1.
Although a TiO ₃ bicrystal substrate is used, the material of the substrate is not limited to SrTiO ₃ and the same effect can be obtained by using a YAlO ₃ substrate.

Example 8. In Example 1, Sr was used as the substrate 1.
Although a TiO ₃ bicrystal substrate is used, the material of the substrate is not limited to SrTiO ₃ but NdAlO ₃
The same effect can be obtained by using a substrate.

Example 9. In Example 1, Sr was used as the substrate 1.
A TiO ₃ bicrystal substrate was used, but the material of the substrate is not limited to SrTiO ₃ , but LaAlO ₃
The same effect can be obtained by using a substrate.

Example 10. In the first embodiment, S is used as the substrate 1.
An rTiO ₃ bicrystal substrate was used, but the material of the substrate is not limited to SrTiO ₃ , but LaSrA
The same effect can be obtained by using an lO4 substrate.

Example 11. In the first embodiment, S is used as the substrate 1.
Although a rTiO ₃ bicrystal substrate was used, the material of the substrate is not limited to SrTiO ₃ , but NdGaO
The same effect can be obtained by using _three substrates.

Example 12. In the first embodiment, S is used as the substrate 1.
Although the rTiO ₃ bicrystal substrate was used, the material of the substrate is not limited to SrTiO ₃ but PrGaO
The same effect can be obtained by using _three substrates.

Example 13 In the first embodiment, S is used as the substrate 1.
An rTiO ₃ bicrystal substrate was used, but the material of the substrate is not limited to SrTiO ₃ , but LaGaO
The same effect can be obtained by using _three substrates.

Example 14 In the first embodiment, S is used as the substrate 1.
Although the rTiO ₃ bicrystal substrate was used, the material of the substrate is not limited to SrTiO ₃ , but LaSrG
The same effect can be obtained by using an aO4 substrate.

Example 15. Although Ba _1-x K _x BiO ₃ was used as the material of the superconducting thin film 3 in Example 1, the material of the superconducting thin film is not limited to Ba _1-x K _x BiO ₃ and a bismuth-based superconducting oxide is used. Even if the same effect is obtained.

Example 16. Although Ba _1-x K _x BiO ₃ was used as the material of the superconducting thin film 3 in Example 1, the material of the superconducting thin film is not limited to Ba _1-x K _x BiO ₃ , but yttrium-based superconducting oxide is used. Even if the same effect is obtained.

Example 17 Although Ba _1-x K _x BiO ₃ was used as the material of the superconducting thin film 3 in Example 1, the material of the superconducting thin film is not limited to Ba _1-x K _x BiO ₃ and a thallium-based superconducting oxide is used. Even if the same effect is obtained.

Example 18. Although Ba _1-x K _x BiO ₃ was used as the material of the superconducting thin film 3 in Example 1, the material of the superconducting thin film is not limited to Ba _1-x K _x BiO ₃ and a mercury-based superconducting oxide is used. Even if the same effect is obtained.

Example 19 In the first embodiment, the trench 101
Although the Ar ion beam etching was used as the method of forming the above, the method of forming the trench is not limited to the ion beam etching, and the same effect can be obtained by using the reactive ion beam etching using Cl 2 or the like.

Example 20. In the first embodiment, the trench 101
Although the Ar ion beam etching was used as the method of forming the above, the method of forming the trench is not limited to the ion beam etching, and the same effect can be obtained by using the reactive ion etching using CF3 or the like.

Example 21. In the first embodiment, the trench 101
Although Ar ion beam etching was used as the method of forming the above, the method of forming the trench is not limited to ion beam etching, and the same effect can be obtained by using plasma etching using CF4 or the like.

Example 22. In the first embodiment, the trench 101
Although the Ar ion beam etching was used as the method for manufacturing the above, the method for forming the trench is not limited to the ion beam etching, and the same effect can be obtained by using wet etching using a phosphoric acid solution or the like.

Example 23. In the first embodiment, the trench 101
Although Ar ion beam etching was used as a method for manufacturing the above, the method for forming the trench is not limited to ion beam etching, and a buffer layer is formed on the substrate after applying and patterning a resist, A similar effect can be obtained by using a lift-off method for removing the film.

Example 24. Hereinafter, this embodiment will be described. FIG. 2 is a cross-sectional view of the superconducting junction showing the present embodiment. In the figure, 3, 4 and 8 are the same or corresponding portions as the conventional example, and 103 is provided on the substrate by plane orientation dependent etching. It is a crystal plane having a plane index (111).

Next, the operation will be described. First, on the Si crystal substrate 8 whose surface has a crystal plane with a plane index (100),
A step with a height of several hundred nm is provided by etching.
At this time, by using an appropriate etching material, it is possible to perform etching at an etching rate that depends on the crystal surface index. In this embodiment, KOH
By using the solution containing the (1), the etching rate of the (100) plane can be made sufficiently higher than the etching rate of the (111) plane.

As a result, a crystal plane having a plane index (111) appears at the boundary between the etched portion of the crystal surface and the portion which is covered with the mask and is not etched. Since the boundary between the (111) plane and the (100) plane is extremely sharp as shown in FIG. 2, a slope 103 as shown in FIG. A sharp grain boundary junction 4 is formed at each of the upper and lower sides of. This grain boundary junction portion is patterned and used as a superconducting junction.

According to this embodiment, since the superconducting junction has sharp and undisturbed grain boundary junctions only at two steps in the step portion, it hardly interferes with the movement of the magnetic flux penetrating the superconducting thin film, and this junction is formed. The 1 / f noise generated in the electric signal of the element used is extremely small.

Example 25. In Example 24, the plane-orientation-dependent etching method using the solution containing KOH was used as the method for producing the step, but the method for producing the step is not limited to the plane-orientation-dependent etching method using the solution containing KOH. The same effect can be obtained by using the plane orientation-dependent etching method using a solution containing NaOH.

Example 26. In Example 24, the plane-orientation-dependent etching method using the solution containing KOH was used as the method for producing the step, but the method for producing the step is not limited to the plane-orientation-dependent etching method using the solution containing KOH. The same effect can be obtained by using the plane orientation dependent etching method using a solution containing hydrazine.

Example 27. In Example 24, the plane-orientation-dependent etching method using the solution containing KOH was used as the method for producing the step, but the method for producing the step is not limited to the plane-orientation-dependent etching method using the solution containing KOH. The same effect can be obtained by using the plane orientation-dependent etching method using a solution containing ethylenediamine.

Example 28. In Example 24, the plane-orientation-dependent etching method using the solution containing KOH was used as the method for producing the step, but the method for producing the step is not limited to the plane-orientation-dependent etching method using the solution containing KOH. The same effect can be obtained by using the plane orientation dependent etching method using a solution containing a quaternary ammonium hydroxide.

Example 29. In Example 24, the plane-orientation-dependent etching method using the solution containing KOH was used as the method for producing the step, but the method for producing the step is not limited to the plane-orientation-dependent etching method using the solution containing KOH. The same effect can be obtained by using the plane-orientation-dependent etching method using a solution containing KOH and 2-propanol.

Example 30. In Example 24, the plane-orientation-dependent etching method using the solution containing KOH was used as the method for producing the step, but the method for producing the step is not limited to the plane-orientation-dependent etching method using the solution containing KOH. The same effect can be obtained by using the plane orientation dependent etching method using a solution containing KOH and hydrazine.

Example 31. In Example 24, the plane-orientation-dependent etching method using the solution containing KOH was used as the method for producing the step, but the method for producing the step is not limited to the plane-orientation-dependent etching method using the solution containing KOH. The same effect can be obtained by using the plane orientation dependent etching method using a solution containing hydrazine and H2O.

Example 32. In Example 24, the plane-orientation-dependent etching method using the solution containing KOH was used as the method for producing the step, but the method for producing the step is not limited to the plane-orientation-dependent etching method using the solution containing KOH. The same effect can be obtained by using the plane orientation dependent etching method using a solution containing methyl ammonium hydroxide.

Example 33. In Example 24, the plane-orientation-dependent etching method using the solution containing KOH was used as the method for producing the step, but the method for producing the step is not limited to the plane-orientation-dependent etching method using the solution containing KOH. , NH4F and Cu (NO ₃ ) 2
The same effect can be obtained by using the plane-orientation-dependent etching method using a solution containing.

Example 34. Hereinafter, this embodiment will be described. FIG. 3 is a cross-sectional view of the superconducting junction showing the present embodiment. In the figure, the numbers 1 to 7 are the same as or corresponding to those in the conventional example, and 104 is formed epitaxially on the superconducting thin film 3. It is a protective film.

Next, the operation will be described. First, the superconducting thin film 3 is formed on the bicrystal substrate 1. Next, a protective film 104 is epitaxially formed on the superconducting thin film 3 using a substance that grows epitaxially. After that, patterning and electrode formation are performed in the same manner as in the conventional example to produce a superconducting junction.

In this example, a SrTiO ₃ bicrystal substrate (10 mm × 10 mm × 1 mm) was used as a substrate, and Ba _{1 -x} K _x BiO ₃ was deposited on the substrate to a thickness of 200 nm by an RF magnetron sputtering method. It was After that, the target was switched and BaBiO ₃ was deposited on the Ba _{1 -x} K _x BiO ₃ film by RF magnetron sputtering to a thickness of 10 nm without taking the substrate out of the film forming apparatus. This thin film was formed into a bridge with a width of 20 μm by reactive etching with ethane gas.

The superconducting critical temperature of this superconducting junction was measured to be 26.2K, which was 1.8K lower than the superconducting critical temperature of 28K before processing. In the superconducting junction according to the conventional method, the superconducting critical temperature was lowered by about 7.5 K, so that the lowering of the critical temperature could be significantly suppressed. The reason for this effect can be explained as follows. In the superconducting junction of this example, Ba _{1 −x} K _x BiO ₃ was used as the superconducting thin film, but the protective film can be formed without damaging the Ba _{1 −x} K _x BiO ₃ thin film, and thus Ba _{1 −x} It is required that the K _x BiO ₃ thin film has a property of preventing deterioration due to the atmosphere.

In particular, it is necessary to suppress the segregation of K, which is the most reactive in the Ba _1-x K _x BiO ₃ thin film. As a protective film for such a purpose, BaBiO ₃
Is valid. Because the crystal structure of Ba _1-x K _x BiO ₃ is cubic, the lattice constant, in the case of most superconducting transition temperature is high Ba0.6K0.4BiO ₃ composition is 4.287A.

On the other hand, the crystal structure of BaBiO ₃ is orthorhombic and its lattice constants are a = 6.180Å and b = 6.
It is 134Å. The lattice constant 4.287Å of Ba0.6K0.4BiO ₃ is √2 times 4.287 × √2 = 6.06.
3, which is almost equal to the lattice constants of BaBiO _{3 in} the a and b axis directions, and the difference is 2% in the a axis direction and 1% in the b axis direction.

Therefore, on the (100) crystal plane of Ba0.6K0.4BiO _3, the ab plane (c) of BaBiO ₃ is formed.
If the (plane) grows with the a and b axes rotated by 45 degrees in the plane, BaBiO ₃ grows epitaxially with a lattice mismatch of only 1-2%. Therefore, Ba0.6K0.4B
It is possible to form a BaBiO ₃ film having excellent crystallinity without affecting the iO ₃ film by strain or the like. Furthermore, B
abio _3, except for K Ba ₁ - is composed of the same elements as _x K _x BiO _3, since the crystallization, there is no influence of the diffusion of elements, can suppress the precipitation of K to the membrane surface.

Also, the processing of the BaBiO ₃ film itself can be performed by Ba _1-x
Since it can be carried out under almost the same conditions as the processing of the K _x BiO ₃ film,
The use of the aBiO ₃ film as the protective film does not cause processing problems. Therefore, if the BaBiO ₃ film is used as the protective film, the deterioration of the superconducting property can be prevented in the process of forming the circuit shape. As described above, it has been proved that the present invention can prevent the deterioration of the superconducting characteristics that occurs during the processing of the superconducting thin film.

Example 35. In Example 34, the protective film 104
Although BaBiO ₃ was used as the material, the material of the protective film is Ba
Not limited to BiO ₃ , the same effect can be obtained by using BaPbO ₃ .

Example 36. Hereinafter, this embodiment will be described. FIG. 4 is a cross-sectional view of the superconducting junction according to the present embodiment. In the figure, the numbers 1 to 7 are the same as or corresponding to those in the above-mentioned conventional example, and 105 is capable of epitaxially forming the superconducting thin film 3 thereon. , A buffer layer formed on the substrate 2.

Next, the operation will be described. First, the buffer layer 105 is formed on the bicrystal substrate 1. At this time, the buffer layer is made of a material capable of epitaxially growing the superconducting thin film 3 to be formed next. Next, the superconducting thin film 3 is formed on the buffer layer 105. After that, patterning and electrode formation are performed in the same manner as in the conventional example to produce a superconducting junction.

In this example, a SrTiO ₃ bicrystal substrate (10 mm × 10 mm × 1 mm) was used as a substrate, and BaBiO ₃ was deposited on the substrate by RF magnetron sputtering to a thickness of 10 nm.
After that, the target is switched, and the Ba _{1 -x} K film is formed on the BaBiO ₃ film without taking the substrate out of the film forming apparatus.
_x BiO ₃ was deposited to a thickness of 200 nm by the RF magnetron sputtering method. This thin film was formed into a bridge with a width of 20 μm by reactive etching with ethane gas.

The superconducting critical current density of this superconducting junction at 4.2K was measured to be about 5 × 10 ⁵ A / cm ² , and B
The critical current density increased about twice as compared with the case without the aBiO ₃ buffer layer. This indicates that the buffer layer relaxed the lattice mismatch between the superconducting thin film and the substrate, and therefore the superconducting thin film could be formed as a high-quality film from the initial stage of growth. As described above, it has been proved that the present invention can significantly improve the quality of the superconducting thin film as compared with the conventional one.

Example 37. In Example 36, the buffer layer 1
Although BaBiO ₃ was used as 05, the material of the buffer layer is not limited to BaBiO ₃ , but BaPbO ₃
The same effect can be obtained by using.

Example 38. As another example, sapphire (α-Al 2) as a substrate, especially for high frequency applications.
When an O ₃ ) substrate is used, the Ba _1-x K _x BiO ₃ thin film can be satisfactorily formed by using MgO as the buffer layer 105.

Example 39. Hereinafter, this embodiment will be described. FIG. 5 is a cross-sectional view of the superconducting junction according to the present embodiment. In the figure, the numbers 1 to 7 are the same as or corresponding to those in the conventional example.

Next, the operation will be described. A superconducting thin film 3 is deposited on the bicrystal substrate 1 by a sputtering method, a laser ablation method or the like. The formed superconducting thin film 3 has a crystal orientation aligned according to the plane orientation of the substrate, and the orientations of the crystal orientation are different on both sides of the bonding portion 2 of the substrate. Therefore, the grain boundary junction portion 4 of the superconducting thin film is formed so as to directly overlap the junction portion 2 of the bicrystal substrate.

Next, the superconducting thin film 3 is patterned by a method such as etching as shown in the figure, so that the grain boundary junction 4 has a thickness of several μm.
It is shaped so as to have a width of several hundreds of μm so as to function as a superconducting junction. Here, the electrode 5 is formed on the superconducting thin film 3, but the material of the electrode 5 is NbO instead of the conventional Ag. A lead wire 7 is connected to the oxide electrode 5 to be used as a circuit.

In this example, a SrTiO ₃ bicrystal substrate (10 mm × 10 mm × 1 mm) was used as a substrate, and Ba _{1 -x} K _x BiO ₃ was deposited on the substrate to a thickness of 200 nm by the RF magnetron sputtering method. It was This thin film was formed into a bridge shape with a width of 20 μm by reactive etching with ethane gas, and further, Ba _{1 −x} K
_An NbO thin film was deposited to a thickness of 200 nm on the xBiO ₃ film to form an electrode. When this superconducting junction was cooled in liquid helium and the superconducting critical current density at the portion just below the electrode at 4.2K was measured, it was about 1.1 × 10 ⁶ A / cm ² , and Ag
The critical current density increased about 1.6 times as compared with the case where the electrode was used.

This is because NbO is a conductive oxide, and it is well compatible with superconducting oxides and does not cause a chemical reaction at the interface with the superconducting thin film that deteriorates the superconducting properties of the superconducting thin film. This is because an ohmic connection can be formed. As described above, it has been proved that the present invention can significantly improve the quality of the superconducting thin film as compared with the conventional one.

Example 40. In Example 39, NbO was used as the material of the electrode 5, but the material of the electrode is not limited to NbO, and the same effect can be obtained by using NdO.

Example 41. In Example 39, NbO was used as the material of the electrode 5, but the material of the electrode is not limited to NbO, and the same effect can be obtained by using ReO ₃ .

Example 42. In Example 39, NbO was used as the material of the electrode 5, but the material of the electrode is not limited to NbO, and the same effect can be obtained by using RuO2.

Example 43. Although NbO was used as the material of the electrode 5 in Example 39, the material of the electrode is not limited to NbO, and the same effect can be obtained by using OsO2.

Example 44. In Example 39, NbO was used as the material of the electrode 5, but the material of the electrode is not limited to NbO, and the same effect can be obtained by using IrO2.

Example 45. Hereinafter, this embodiment will be described. FIG. 6 is a cross-sectional view of the superconducting junction according to the present embodiment, in which 1 is the same portion as the above-mentioned conventional example,
106 is a lower BiSr (Ca, Y) CuO superconducting thin film,
107 is a BiSr (Ca, Y) CuO insulator film, 108
Is an upper BiSr (Ca, Y) CuO superconducting thin film, 109
Is an insulating film for wiring separation, and 110 is a superconducting thin film for wiring.

Next, the operation will be described. A lower BiSr (Ca, Y) CuO superconducting thin film 106 is deposited on the substrate 1 by a sputtering method or the like. At this time, the composition ratio of Y is reduced so that the thin film exhibits superconducting characteristics.
Next, a BiSr (Ca, Y) CuO thin film 107 having a large Y composition ratio (about 0.4 or more) and exhibiting the properties of an insulator is thinly deposited.

Subsequently, again, the upper Bi having a small Y composition ratio
A Sr (Ca, Y) CuO superconducting thin film 108 is deposited.
Since all the thin films having such a three-layer structure are made of the same kind of material, the interfaces are very smooth, and the superconducting thin films at the upper and lower portions are good-quality superconducting films even at the interface with the insulating film.

When another substance having a completely different composition is used as the insulating film, the quality of the superconducting thin film at the interface portion is likely to deteriorate. However, by forming the insulating film with the same kind of substance as the superconducting thin film, the coherence of the superconducting conductor is improved. It is possible to obtain a structure in which high-quality superconducting films are brought close to each other to a distance substantially equal to the length and they are separated by an insulating film. For this reason, the portions sandwiching this insulating film form a superconducting junction of laminated type superconductor-insulator-superconductor.

After that, the upper superconducting thin film 108 is removed by a method such as etching, leaving only a minute area, and the periphery thereof is covered with an insulating film 109, and then the superconducting thin film 11 for wiring is formed.
0 is deposited to form a device shape. Since the superconducting junction produced in this manner uses a Bi-based superconductor having a high critical temperature, it can produce a larger output than before when used at a low temperature.
By increasing the operating temperature, the burden on the cooling system can be reduced.

Example 46. In Example 45, BiSr (Ca, Y) CuO was used as the superconductor, but the superconductor is not limited to BiSr (Ca, Y) CuO, and BiSrCa (Cu, Fe) O may be used.
At this time, by decreasing the Fe composition ratio, a superconductor can be obtained, and by increasing the Fe composition ratio, an insulator can be obtained. Therefore, an element manufactured by the same method as that of the above-described example has the same structure as that of the above-mentioned example. The effect of is obtained.

Example 47. Hereinafter, this embodiment will be described. FIG. 7 is a cross-sectional view showing a connecting portion between the superconducting thin film and the resistor thin film of the superconducting junction showing the present embodiment.
1 to 3 are parts which are the same as or correspond to those of the conventional example,
Reference numeral 10 is a resistor thin film of TaN or the like, and 111 is a low resistance metal thin film of Au or the like that does not form an altered layer at the interface with the superconducting thin film.

Next, the operation will be described. Ba ₁ - _x is formed on the substrate 1 by a sputtering method, a laser ablation method, or the like.
A superconducting thin film ₃ such as K _x BiO ₃ is deposited. This is processed in the same manner as the above-mentioned conventional example, and further, the resistor thin film 10 made of a high resistance metal such as TaN as a terminator for microwave application is formed. Instead of arranging them so as to overlap the superconducting thin film 3 as described above, they are arranged so as not to overlap each other as shown in FIG.

Then, a low resistance metal thin film 111 is formed so as to overlap between the two, and the superconducting thin film 3 and the resistor thin film 10 are formed.
And are electrically connected. At this time, as the material of the low resistance metal thin film 111, a substance that does not cause an altered layer at the interface between the superconducting thin film 3 and the resistor thin film 10 is selected. For example, when Ba _1-x K _x BiO ₃ is used as the superconducting thin film 3 and TaN is used as the resistor thin film 10, Au is used as the low resistance metal thin film 111.

Since the superconducting junction of this example is constructed as described above, no deterioration layer is formed at the interface between the superconducting thin film and the high resistance metal thin film, and deterioration of the characteristics of the element can be prevented.

Example 48. Although the purpose of use of the device is not specified in Embodiment 47, the superconducting thin film is formed so as to be used as a microwave strip line as in this embodiment, and the resistor thin film can be used as a terminal resistance of the strip line. The formation of the superconducting junction makes it possible to use the superconducting junction as a microwave mixer. Conventionally, it was not possible to use a superconducting junction using a high temperature superconducting thin film as a high frequency microwave mixer due to the presence of an interfacial alteration layer, but according to the present invention, it is possible to use such a superconducting junction as a microwave mixer. It will be possible.

[0213]

The superconducting junction according to the invention of claim 1 is
A crystal grain that forms a superconducting junction by forming a trench formed on a substrate and a superconducting thin film formed on the substrate, and forming a superconducting junction of the superconducting thin film in an overhang shape on the trench. The field does not touch the substrate. Therefore,
The flow of magnetic flux at the crystal grain boundaries is smooth and undisturbed by the influence of the turbulence of the crystal grain boundaries of the substrate.
The effect is that f noise is greatly reduced.

In the superconducting junction according to the second aspect of the present invention, the superconducting junction portion of the superconducting thin film is formed overhanging over the trench by forming the trench on the bicrystal substrate and providing the superconducting thin film on the bicrystal substrate. The crystal grain boundaries that form the superconducting junction in order to form the film are not in contact with the substrate. Therefore, the flow of the magnetic flux at the crystal grain boundaries is not affected by the disturbance of the crystal grain boundaries of the substrate and is not disturbed smoothly, so that the 1 / f noise of the signal flowing through the junction is greatly reduced.

In the superconducting junction according to the third aspect of the present invention, the trench is formed on the single crystal substrate and the superconducting thin film is provided on the bicrystal substrate, so that the superconducting junction of the superconducting thin film overhangs the trench. The crystal grain boundaries that form the superconducting junction in order to form the film are not in contact with the substrate. Therefore, the flow of the magnetic flux at the crystal grain boundaries is not affected by the disturbance of the crystal grain boundaries of the substrate and is not disturbed smoothly, so that the 1 / f noise of the signal flowing through the junction is greatly reduced.

The superconducting junction according to the invention of claim 4 is S
By forming the trench on the rTiO ₃ substrate and providing the superconducting thin film on the bicrystal substrate, the superconducting junction of the superconducting thin film is formed in the overhang shape on the trench. Does not touch the substrate. Therefore, the flow of the magnetic flux at the crystal grain boundaries is not affected by the disturbance of the crystal grain boundaries of the substrate and is not disturbed smoothly, so that the 1 / f noise of the signal flowing through the junction is greatly reduced.

The superconducting junction according to the invention of claim 5 is M
By forming the trench on the gO substrate and providing the superconducting thin film on the bicrystal substrate, the superconducting junction of the superconducting thin film is formed in an overhang shape on the trench, so that the grain boundaries forming the superconducting junction are Do not touch the substrate. Therefore, the flow of the magnetic flux at the crystal grain boundaries is not affected by the disturbance of the crystal grain boundaries of the substrate and is not disturbed smoothly, so that the 1 / f noise of the signal flowing through the junction is greatly reduced.

In the superconducting junction according to the invention of claim 6, the trench is formed on the sapphire (α-Al ₂ O ₃ ) substrate, and the superconducting thin film is provided on the bicrystal substrate. The crystal grain boundary forming the superconducting junction is not in contact with the substrate because it is formed in the overhang shape. Therefore, the flow of the magnetic flux at the crystal grain boundaries is not affected by the disturbance of the crystal grain boundaries of the substrate and is not disturbed smoothly, so that the 1 / f noise of the signal flowing through the junction is greatly reduced.

The superconducting junction according to the invention of claim 7 is Y
Since the superconducting thin film is provided on the SZ (yttrium-stabilized zirconia) substrate, the superconducting junction of the superconducting thin film is formed overhanging on the trench, so that the grain boundaries forming the superconducting junction do not contact the substrate. Therefore, the flow of the magnetic flux at the crystal grain boundaries is not affected by the disturbance of the crystal grain boundaries of the substrate and is not disturbed smoothly, so that the 1 / f noise of the signal flowing through the junction is greatly reduced.

The superconducting junction according to the invention of claim 8 is C
Since the superconducting thin film is provided on the aTiO ₃ substrate, the superconducting junction part of the superconducting thin film is formed overhanging on the trench, so that the crystal grain boundary forming the superconducting junction does not contact the substrate. Therefore, the flow of the magnetic flux at the crystal grain boundaries is not affected by the disturbance of the crystal grain boundaries of the substrate and is not disturbed smoothly, so that the 1 / f noise flowing through the junction is greatly reduced.

The superconducting junction according to the invention of claim 9 is Y
By providing the superconducting thin film on the AlO ₃ substrate, the superconducting junction of the superconducting thin film is formed overhanging on the trench, so that the crystal grain boundary forming the superconducting junction does not contact the substrate. Therefore, the flow of the magnetic flux at the crystal grain boundaries is not affected by the disturbance of the crystal grain boundaries of the substrate and is not disturbed smoothly, so that the 1 / f noise of the signal flowing through the junction is greatly reduced.

The superconducting junction according to the invention of claim 10 is
Since the superconducting thin film is provided on the NdAlO ₃ substrate, the superconducting junction part of the superconducting thin film is formed overhanging on the trench, so that the crystal grain boundary forming the superconducting junction does not contact the substrate. Therefore, the flow of the magnetic flux at the crystal grain boundaries is not affected by the disturbance of the crystal grain boundaries of the substrate and is not disturbed smoothly, so that the 1 / f noise of the signal flowing through the junction is greatly reduced.

The superconducting junction according to the invention of claim 11 is
Since the superconducting thin film is provided on the LaAlO ₃ substrate, the superconducting junction part of the superconducting thin film is formed overhanging on the trench, so that the crystal grain boundary forming the superconducting junction does not contact the substrate. Therefore, the flow of the magnetic flux at the crystal grain boundaries is not affected by the disturbance of the crystal grain boundaries of the substrate and is not disturbed smoothly, so that the 1 / f noise of the signal flowing through the junction is greatly reduced.

The superconducting junction according to the invention of claim 12 is
Since the superconducting thin film is provided on the LaSrAlO ₄ substrate, the superconducting junction part of the superconducting thin film is formed overhanging on the trench, so that the crystal grain boundary forming the superconducting junction does not contact the substrate. Therefore, the flow of the magnetic flux at the crystal grain boundaries is not affected by the disturbance of the crystal grain boundaries of the substrate and is not disturbed smoothly, so that the 1 / f noise of the signal flowing through the junction is greatly reduced.

The superconducting junction according to the invention of claim 13 is
Since the superconducting thin film is provided on the NdGaO ₃ substrate, the superconducting junction part of the superconducting thin film is formed overhanging on the trench, so that the crystal grain boundary forming the superconducting junction does not contact the substrate. Therefore, the flow of the magnetic flux at the crystal grain boundaries is not affected by the disturbance of the crystal grain boundaries of the substrate and is not disturbed smoothly, so that the 1 / f noise of the signal flowing through the junction is greatly reduced.

The superconducting junction according to the invention of claim 14 is
Since the superconducting thin film is provided on the PrGaO ₃ substrate, the superconducting junction portion of the superconducting thin film is formed in the overhang shape on the trench, so that the crystal grain boundary forming the superconducting junction does not contact the substrate. Therefore, the flow of the magnetic flux at the crystal grain boundaries is not affected by the disturbance of the crystal grain boundaries of the substrate and is not disturbed smoothly, so that the 1 / f noise of the signal flowing through the junction is greatly reduced.

The superconducting junction according to the invention of claim 15 is
Since the superconducting thin film is provided on the LaGaO ₃ substrate, the superconducting junction of the superconducting thin film is formed overhanging on the trench, so that the crystal grain boundary forming the superconducting junction does not contact the substrate. Therefore, the flow of the magnetic flux at the crystal grain boundaries is not affected by the disturbance of the crystal grain boundaries of the substrate and is not disturbed smoothly, so that the 1 / f noise of the signal flowing through the junction is greatly reduced.

The superconducting junction according to the invention of claim 16 is
Since the superconducting thin film is provided on the LaSrGaO4 substrate, the superconducting junction part of the superconducting thin film is formed in an overhang shape on the trench, so that the crystal grain boundary forming the superconducting junction does not contact the substrate. Therefore, the flow of the magnetic flux at the crystal grain boundaries is not affected by the disturbance of the crystal grain boundaries of the substrate and is not disturbed smoothly, so that the 1 / f noise of the signal flowing through the junction is greatly reduced.

The superconducting junction according to the seventeenth aspect of the invention is
A trench formed on a substrate, and a superconducting thin film of a Ba _{1 -x} K _x BiO ₃ superconducting material formed on the substrate,
Since the superconducting junction of the superconducting thin film is formed in an overhang shape on the trench, the crystal grain boundary forming the superconducting junction does not contact the substrate, so that the flow of magnetic flux at the crystal grain boundary is different from that of the crystal grain boundary of the substrate. It is effective in that it is smooth and undisturbed without being affected by the disturbance.

The superconducting junction according to the invention of claim 18 is
A trench prepared on a substrate and a superconducting thin film of a bismuth-based superconducting oxide superconducting material formed on the substrate, wherein a superconducting junction of the superconducting thin film is formed in an overhang shape on the trench. Since the crystal grain boundaries forming the superconducting junction are not in contact with the substrate, there is an effect that the flow of magnetic flux at the crystal grain boundaries is not affected by the disturbance of the crystal grain boundaries of the substrate and becomes smooth and undisturbed.

The superconducting junction according to the invention of claim 19 is
A trench prepared on a substrate and a superconducting thin film of yttrium-based superconducting oxide superconducting material formed on the substrate are provided, and a superconducting junction of the superconducting thin film is formed in an overhang shape on the trench. Since the crystal grain boundaries forming the superconducting junction are not in contact with the substrate, the flow of the magnetic flux at the crystal grain boundaries is not affected by the disturbance of the crystal grain boundaries of the substrate, and is therefore smooth and undisturbed.

[0232] The superconducting junction according to the invention of claim 20 is
A trench prepared on a substrate and a superconducting thin film of a thallium-based superconducting oxide superconducting material formed on the substrate, wherein a superconducting junction of the superconducting thin film is formed in an overhang shape on the trench. Since the crystal grain boundaries forming the superconducting junction are not in contact with the substrate, there is an effect that the flow of magnetic flux at the crystal grain boundaries is not affected by the disturbance of the crystal grain boundaries of the substrate and becomes smooth and undisturbed.

The superconducting junction according to the twenty-first aspect of the invention is
A trench formed on the substrate, and a superconducting thin film of a mercury-based superconducting oxide superconducting material formed on the substrate,
Since the superconducting junction of the superconducting thin film is formed in an overhang shape on the trench, the crystal grain boundary forming the superconducting junction does not contact the substrate, so that the flow of magnetic flux at the crystal grain boundary is different from that of the crystal grain boundary of the substrate. It is effective in that it is smooth and undisturbed without being affected by the disturbance.

According to a twenty-second aspect of the present invention, there is provided a method of manufacturing a superconducting junction, which comprises a step of forming a trench on a substrate and a step of forming a superconducting film on the substrate so that the superconducting junction is formed on the trench. As a result, the superconducting junction of the superconducting thin film is formed as an overhang on the trench and the crystal grain boundary forming the superconducting junction does not contact the substrate, so the flow of magnetic flux at the crystal grain boundary is It has the effect of becoming smooth and undisturbed without being affected by the disturbance.

In the method of manufacturing a superconducting junction according to the twenty-third aspect of the present invention, the superconducting junction is formed by forming an overhang on the trench by using ion beam etching for manufacturing the trench in the method of manufacturing the superconducting junction. Since the formed crystal grain boundaries are not in contact with the substrate, there is an effect that the flow of magnetic flux at the crystal grain boundaries is not affected by the disturbance of the crystal grain boundaries of the substrate and becomes smooth and undisturbed.

According to a twenty-fourth aspect of the present invention, there is provided a method of manufacturing a superconducting junction, wherein in the method of manufacturing a superconducting junction, reactive ion beam etching is used to form a trench to form an overhang shape on the trench. Since the crystal grain boundaries forming the junction are not in contact with the substrate, the flow of the magnetic flux at the crystal grain boundaries is not affected by the disturbance of the crystal grain boundaries of the substrate, and has the effect of becoming smooth and undisturbed.

According to a twenty-fifth aspect of the present invention, there is provided a method of producing a superconducting junction, wherein reactive ion etching is used for producing a trench in the method of producing a superconducting junction to form an overhang on the trench. Since the crystal grain boundary forming the crystal grain boundary does not contact the substrate, the flow of magnetic flux at the crystal grain boundary is not affected by the disturbance of the crystal grain boundary of the substrate, and is smooth and free from disturbance.

According to the 26th aspect of the present invention, there is provided a method for forming a superconducting junction, wherein in the method for producing a superconducting junction, plasma etching is used to form a trench to form an overhang shape on the trench to form the superconducting junction. Since the crystal grain boundaries are not in contact with the substrate, the flow of magnetic flux at the crystal grain boundaries is not affected by the disorder of the crystal grain boundaries of the substrate, and is smooth and undisturbed.

In the method for forming a superconducting junction according to the twenty-seventh aspect of the present invention, the grain boundaries forming the superconducting junction are not in contact with the substrate by forming the superconducting junction in an overhang shape by using wet etching. The flow of magnetic flux at the crystal grain boundaries is not affected by the disturbance of the crystal grain boundaries of the substrate, and has the effect of becoming smooth and undisturbed.

According to a twenty-eighth aspect of the present invention, there is provided a method for forming a superconducting junction, wherein a lift-off method is used for producing a trench in the method for producing a superconducting junction to form a superconducting junction on the trench to form a superconducting junction. Since the crystal grain boundaries are not in contact with the substrate, the flow of magnetic flux at the crystal grain boundaries is not affected by the disorder of the crystal grain boundaries of the substrate, and is smooth and undisturbed.

[0241] The superconducting junction according to the invention of claim 29 is:
The sharp grain boundary junction formed on the sharp step formed on the substrate by the plane orientation dependent etching can be used as the Josephson junction, so that the 1 / f noise of the signal flowing through the junction is significantly reduced. effective.

The superconducting junction according to the invention of claim 30 is
The sharp grain boundary junction formed on the sharp step formed by the plane orientation dependent etching with the solution containing KOH on the substrate can be used as the Josephson junction, so that 1 / f noise of the signal flowing through the junction is reduced. It has the effect of being greatly reduced.

The superconducting junction according to the invention of claim 31 is
The sharp grain boundary junction formed on the sharp step formed by the plane-direction dependent etching with the solution containing NaOH on the substrate can be used as the Josephson junction, so that 1 / f noise of the signal flowing through the junction is reduced. It has the effect of being greatly reduced.

The superconducting junction according to the invention of claim 32 is
The sharp grain boundary junction formed on the sharp step formed by the plane orientation dependent etching with the solution containing hydrazine on the substrate can be used as the Josephson junction, so that 1 / f noise of the signal flowing through the junction is reduced. It has the effect of being greatly reduced.

The superconducting junction according to the invention of claim 33 is
A sharp grain boundary junction formed on a sharp step formed by plane-direction dependent etching with a solution containing ethylediamine on the substrate can be used as a Josephson junction, so that 1 / f noise of a signal flowing through the junction is reduced. It has the effect of being greatly reduced.

The superconducting junction according to the invention of claim 34 is
The sharp grain boundary junction formed on the sharp step created by the plane orientation dependent etching with the solution containing quaternary ammonium hydroxide on the substrate can be used as a Josephson junction, so that the signal flowing through the junction is 1 /
The effect is that f noise is greatly reduced.

The superconducting junction according to the invention of claim 35 is
The sharp grain boundary junction formed on the sharp step formed by the plane orientation dependent etching with the solution containing KOH and 2-propanol on the substrate can be used as the Josephson junction, so that the signal flowing through the junction is /
The effect is that f noise is greatly reduced.

The superconducting junction according to the thirty-sixth aspect of the invention is
The sharp grain boundary junction formed on the sharp step formed by the plane-orientation-dependent etching with the solution containing KOH and humanradin on the substrate can be used as the Josephson junction, so 1 / f of the signal flowing through the junction The effect is that noise is greatly reduced.

The superconducting junction according to the invention of claim 37 is
Since the sharp grain boundary junction formed on the sharp step formed by the plane orientation dependent etching with the solution containing humanradine and H ₂ O on the substrate can be used as the Josephson junction, 1 The effect is that the / f noise is greatly reduced.

The superconducting junction according to the thirty-eighth aspect of the invention is
Since a sharp grain boundary junction formed on a sharp step formed by plane-direction dependent etching with a solution containing methylammonium hydroxide on the substrate can be used as a Josephson junction
The effect is that the / f noise is greatly reduced.

The superconducting junction according to the invention of claim 39 is
Since the sharp grain boundary junction formed on the sharp step formed by the plane orientation dependent etching with the solution containing NH ₄ F and Cu (NO ₃ ) ₂ on the substrate can be used as the Josephson junction, the junction 1 of the signal flowing through
The effect is that f noise is greatly reduced.

The superconducting junction according to the invention of claim 40 is
A superconducting thin film that forms a superconducting junction by forming a superconducting junction on a substrate, a superconducting thin film formed on the substrate, and a superconducting junction formed by the superconducting junction of the superconducting thin film, and having a protective film epitaxially formed on the superconducting thin film. It is possible to protect the superconducting thin film without adverse effects such as distortion on the superconducting thin film, and the superconducting thin film is used as an organic solvent such as acetone for removing the photoresist for photoengraving and the photoresist for the process of processing the superconducting junction into a circuit shape. Therefore, there is an effect that it is possible to prevent deterioration of superconducting characteristics in the process of processing the superconducting junction into a circuit shape.

The superconducting junction according to the invention of claim 41 is
A substrate, a superconducting thin film of Ba _{1- x} K _x BiO ₃ formed on the substrate, and a superconducting junction composed of a superconducting junction portion of the superconducting thin film, and a protective film of BaBiO ₃ epitaxially formed on the superconducting thin film. By having
The superconducting thin film that forms the superconducting junction can be protected without adversely affecting the superconducting thin film, such as distortion, and the superconducting thin film removes the photolithography photoresist or photoresist during the process of processing the superconducting junction into a circuit shape. Since it is not exposed to an organic solvent such as acetone, it is possible to prevent deterioration of superconducting characteristics during the process of processing the superconducting junction into a circuit shape.

The superconducting junction according to the invention of claim 42 is
A substrate, a Ba _{1- x} K _x BiO ₃ superconducting thin film formed on the substrate, and a superconducting junction composed of a superconducting junction of the superconducting thin film, and a protective film of BaPbO ₃ epitaxially formed on the superconducting thin film. By having
The superconducting thin film that forms the superconducting junction can be protected without adversely affecting the superconducting thin film, such as distortion, and the superconducting thin film removes the photolithography photoresist or photoresist during the process of processing the superconducting junction into a circuit shape. Since it is not exposed to an organic solvent such as acetone, it is possible to prevent deterioration of superconducting characteristics during the process of processing the superconducting junction into a circuit shape.

The superconducting junction according to the invention of claim 43 is:
The superconducting junction composed of the substrate, the superconducting thin film formed on the substrate, and the superconducting junction part of the superconducting thin film has a buffer layer capable of epitaxially forming the superconducting thin film between the substrate and the superconducting thin film. Since the thin film can be formed with high quality without being affected by the lattice mismatch with the substrate, there is an effect that the characteristics of the superconducting junction are improved.

The superconducting junction according to the invention of claim 44 is:
The superconducting thin film formed on the substrate, the superconducting thin film formed on the substrate, and the superconducting junction part of the superconducting thin film, and the superconducting thin film made of Ba _1-x K _x BiO ₃ are epitaxially formed between the substrate and the superconducting thin film. Since it has a buffer layer of BaBiO _{3 that} can be formed, the superconducting thin film can be formed with high quality without being affected by lattice mismatch with the substrate, so that the characteristics of the superconducting junction are improved.

The superconducting junction according to the 45th aspect of the invention is
The superconducting thin film formed on the substrate, the superconducting thin film formed on the substrate, and the superconducting junction part of the superconducting thin film, and the superconducting thin film made of Ba _1-x K _x BiO ₃ are epitaxially formed between the substrate and the superconducting thin film. BaBaPbO _{3 that} can be formed
Since the superconducting thin film can be formed with high quality without being affected by the lattice mismatch with the substrate, it has the effect of improving the characteristics of the superconducting junction.

The superconducting junction according to the 46th aspect of the invention is
For a superconducting junction composed of a substrate using sapphire, a superconducting thin film formed on the substrate, and a superconducting junction part of the superconducting thin film, a Ba _1-x film is provided between the substrate and the superconducting thin film.
Since the superconducting thin film made of K _x BiO ₃ has the MgO ₃ buffer layer that can be epitaxially formed, the superconducting thin film can be formed with high quality without being affected by the lattice mismatch with the substrate, so that the characteristics of the superconducting junction are improved. There is an effect.

The superconducting junction according to the 47th aspect of the invention is
A superconducting thin film, a superconducting junction part of the superconducting thin film, and a superconducting junction composed of an electrode deposited on the superconducting thin film, by using an oxide thin film as the electrode,
Since the material of the electrode deposited on the superconducting thin film is not a metal but a conductive oxide, it is possible to suppress the generation of an altered layer particularly at the interface between the superconducting thin film using an oxide superconductor and the electrode. Therefore, there is an effect that a good ohmic connection can be obtained between the superconducting thin film and the electrode.

The superconducting junction according to the 48th aspect of the invention is
In a superconducting junction composed of a superconducting thin film, a superconducting junction part of the superconducting thin film, and an electrode deposited on the superconducting thin film, an oxide thin film is used as the electrode, and in situ after the superconducting thin film is formed. Since the electrode is formed, it is possible to suppress the generation of an altered layer at the interface between the superconducting thin film using the oxide superconductor and the electrode. Therefore, there is an effect that a good ohmic connection can be obtained between the superconducting thin film and the electrode.

The superconducting junction according to the invention of claim 49 is
By using an NbO oxide thin film as the electrode in a superconducting junction composed of a superconducting thin film, a superconducting junction part of the superconducting thin film, and an electrode deposited on the superconducting thin film, Ba _1-x K _x Since the material of the electrode deposited on the BiO ₃ superconducting thin film is not a metal but a conductive oxide,
In particular, it is possible to suppress the generation of an altered layer at the interface between the superconducting thin film using an oxide superconductor and the electrode. Therefore, there is an effect that a good ohmic connection can be obtained between the superconducting thin film and the electrode.

The superconducting junction according to the invention of claim 50 is
By using an NdO oxide thin film as the electrode in a superconducting junction composed of a superconducting thin film, a superconducting junction part of the superconducting thin film, and an electrode deposited on the superconducting thin film, Ba _1-x K _x Since the material of the electrode deposited on the BiO ₃ superconducting thin film is not a metal but a conductive oxide,
In particular, it is possible to suppress the generation of an altered layer at the interface between the superconducting thin film using an oxide superconductor and the electrode. Therefore, there is an effect that a good ohmic connection can be obtained between the superconducting thin film and the electrode.

The superconducting junction according to the invention of claim 51 is
By using an oxide thin film of ReO ₃ as the electrode in a superconducting junction composed of a superconducting thin film, a superconducting junction part of the superconducting thin film, and an electrode deposited on the superconducting thin film, Ba _1-x K _Since the material of the electrode deposited on the superconducting thin film of xBiO ₃ is not a metal but a conductive oxide, the generation of a deteriorated layer at the interface between the superconducting thin film and the electrode using an oxide superconductor is suppressed. be able to. Therefore, there is an effect that a good ohmic connection can be obtained between the superconducting thin film and the electrode.

The superconducting junction according to the invention of claim 52 is
By using a RuO ₂ oxide thin film as the electrode in a superconducting junction composed of a superconducting thin film, a superconducting junction part of the superconducting thin film, and an electrode deposited on the superconducting thin film, Ba _1-x K _Since the material of the electrode deposited on the superconducting thin film of xBiO ₃ is not a metal but a conductive oxide, the generation of a deteriorated layer at the interface between the superconducting thin film and the electrode using an oxide superconductor is suppressed. be able to. Therefore, there is an effect that a good ohmic connection can be obtained between the superconducting thin film and the electrode.

The superconducting junction according to the invention of claim 53 is
By using an oxide thin film of OsO ₂ as the electrode in a superconducting junction composed of a superconducting thin film, a superconducting junction part of the superconducting thin film, and an electrode deposited on the superconducting thin film, Ba _1-x K _Since the material of the electrode deposited on the superconducting thin film of xBiO ₃ is not a metal, it is possible to suppress the generation of an altered layer at the interface between the superconducting thin film using an oxide superconductor and the electrode. Therefore, there is an effect that a good ohmic connection can be obtained between the superconducting thin film and the electrode.

The superconducting junction according to the invention of claim 54 is:
By using an IrO ₂ oxide thin film as an electrode in a superconducting junction composed of a superconducting thin film, a superconducting junction of the superconducting thin film, and an electrode deposited on the superconducting thin film, Ba _1-x K _x BiO ₃ Since the material of the electrode deposited on the superconducting thin film of is a conductive oxide, not a metal, it is possible to suppress the generation of a deteriorated layer at the interface between the superconducting thin film and the electrode using an oxide superconductor. . Therefore, there is an effect that a good ohmic connection can be obtained between the superconducting thin film and the electrode.

The superconducting junction according to the 55th aspect of the present invention is
In a superconducting junction composed of a superconducting thin film and a superconducting junction of the superconducting thin film, a Bi-based superconductor is used as the superconducting thin film, and an insulator is formed by changing the composition ratio of a part of the Bi superconductor. There is an effect that the sandwiched region is used as a superconducting junction.

The superconducting junction according to the 56th aspect of the invention is
Bi as a superconducting thin film in the superconducting junction according to claim 55.
There is an effect that Sr (Ca, Y) CuO is used, and a composition having an excess of Y is used as a part of the Sr (Ca, Y) CuO to form an insulator, and a region sandwiching the insulator part is used as a superconducting junction.

The superconducting junction according to the 57th aspect of the invention is
Bi as a superconducting thin film in the superconducting junction according to claim 55.
SrCa (Cu, Fe) O is used, and a composition with an excess of Fe is used as a part thereof to form an insulator, and the region sandwiching this insulator part is used as a superconducting junction. Since the body is used, the operating temperature of the superconducting junction can be increased, and the burden on the cooling system can be significantly reduced.

[0270] The superconducting junction according to the invention of claim 58 is:
In a superconducting junction having a superconducting thin film and a superconducting junction part of the superconducting thin film, and having a resistor thin film connected to the superconducting thin film, the superconducting thin film and the resistor thin film are arranged without overlapping, and the superconducting thin film is formed. And the resistor thin film is connected with a low-resistance metal thin film, and since the superconducting thin film and the high-resistance metal thin film are not placed on top of each other, an altered layer does not occur at the interface between them, and the device characteristics There is an effect that deterioration of can be prevented.

The superconducting junction according to the invention of claim 59 is
In a superconducting junction having a superconducting thin film and a resistor thin film connected to the superconducting thin film, the superconducting thin film of Ba _1-x K _x BiO _{3 and} the superconducting thin film
The aN resistor thin film is arranged without overlapping, and the superconducting thin film and the resistor thin film are connected by a low resistance Au metal thin film. Since the superconducting thin film and the high resistance metal thin film are not arranged on top of each other, An altered layer does not occur at the interface between them, and it is possible to prevent deterioration of device characteristics.

The superconducting junction according to the invention of claim 60 is
In a superconducting junction having a superconducting thin film and a superconducting junction part of the superconducting thin film, and having a resistor thin film connected to the superconducting thin film, the superconducting thin film and the resistor thin film by a microwave strip line are used as a terminator of the strip line. The superconducting thin film and the high resistance metal thin film are not placed on top of each other by placing a low resistance metal thin film which is placed on both the superconducting thin film and the resistor thin film so that they are not placed on top of each other. An altered layer does not occur at the interface, and it is possible to prevent deterioration of device characteristics.

[Brief description of drawings]

FIG. 1 is a sectional view showing a superconducting junction according to first to twenty-third embodiments of the present invention.

FIG. 2 is a sectional view showing a superconducting junction according to 24th to 33rd embodiments of the present invention.

FIG. 3 is a schematic view showing superconducting junctions according to 34th to 35th embodiments of the present invention.

FIG. 4 is a schematic view showing superconducting junctions according to the 36th to 38th embodiments of the present invention.

FIG. 5 is a schematic view showing superconducting junctions according to the 39th to 44th embodiments of the present invention.

FIG. 6 is a sectional view showing a superconducting junction according to the 45th to 46th embodiments of the present invention.

FIG. 7 is a sectional view showing a superconducting junction according to the 47th to 48th embodiments of the present invention.

FIG. 8 is a schematic view of a conventional superconducting junction for explaining the novelty of the present invention.

FIG. 9 is a cross-sectional view showing another conventional superconducting junction for explaining the novelty of the present invention.

FIG. 10 is a sectional view showing another conventional superconducting junction for explaining the novelty of the present invention.

[Explanation of symbols]

1 substrate, 2 grain boundary junction between substrates, 3 superconducting thin film, 4
Grain boundary junction of superconducting thin film, 5 current contact, 6
Ag paste, 7 lead wires, 8 substrate surface index (10
0) crystal plane, 9 slopes of steps provided on the substrate, 10
Resistor thin film, 11 Altered layer formed at interface between superconducting thin film and resistor thin film, 101 trench, 102 Grain boundary junction of superconducting thin film formed on trench, 103 Crystal face of surface index (111) of substrate, 104 Protective film, 105
Buffer layer, 106 lower superconducting thin film, 107 insulating film, 108 upper insulating thin film, 109 wiring separating insulating film, 110 wiring superconducting thin film, 111 low resistance metal thin film.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Kenichi Kuroda 1-1-1, Tsukaguchihonmachi, Amagasaki City Mitsubishi Electric Corporation Semiconductor Research Laboratory (72) Inventor Ichiyoshi Kojima 8-1-1 Tsukaguchihonmachi, Amagasaki Mitsubishi Electric Corporation Semiconductor Basic Research Center

Claims (60)

[Claims] 1. A superconducting thin film formed on a substrate, and a superconducting thin film formed on the substrate, wherein a superconducting junction portion of the superconducting thin film is formed in an overhang shape on the trench. And superconducting junction. 2. The superconducting junction according to claim 1, wherein a bicrystal substrate is used as a substrate for forming the trench. 3. The superconducting junction according to claim 1, wherein a single crystal substrate is used as a substrate for forming the trench. 4. SrTi as a substrate for forming a trench
The superconducting junction according to claim 1, wherein an O ₃ substrate is used. 5. MgO ₃ as a substrate for forming a trench
The superconducting junction according to claim 1, wherein a substrate is used. 6. The superconducting junction according to claim 1, wherein a sapphire (α-Al ₂ O ₃ ) substrate is used as a substrate for forming the trench. 7. YSZ as a substrate for forming a trench
The superconducting junction according to claim 1, wherein a (yttrium-stabilized zirconia) substrate is used. 8. CaTi as a substrate for forming a trench
The superconducting junction according to claim 1, wherein an O ₃ substrate is used. 9. YAlO as a substrate for forming a trench
The superconducting junction according to claim 1, wherein _three substrates are used. 10. NdA as a substrate for forming a trench
The superconducting junction according to claim 1, wherein a 10 ₃ substrate is used. 11. LaA as a substrate for forming a trench
The superconducting junction according to claim 1, wherein a 10 ₃ substrate is used. 12. LaS as a substrate for forming a trench
The superconducting junction according to claim 1, wherein an rAlO ₄ substrate is used. 13. NdG as a substrate for forming a trench
The superconducting junction according to claim 1, wherein an aO ₃ substrate is used. 14. PrG as a substrate for forming a trench
The superconducting junction according to claim 1, wherein an aO ₃ substrate is used. 15. LaG as a substrate for forming a trench
The superconducting junction according to claim 1, wherein an aO ₃ substrate is used. 16. LaS as a substrate for forming a trench
The superconducting junction according to claim 1, wherein an rGaO ₄ substrate is used. 17. A superconducting material of Ba _1-x K _x BiO ₃
The superconducting junction according to claim 1, wherein 18. The superconducting junction according to claim 1, wherein a bismuth-based superconducting oxide is used as the superconducting material. 19. The superconducting junction according to claim 1, wherein yttrium-based superconducting oxide is used as the superconducting material. 20. The superconducting junction according to claim 1, wherein a thallium-based superconducting oxide is used as the superconducting material. 21. The superconducting junction according to claim 1, wherein a mercury-based superconducting oxide is used as the superconducting material. 22. A step of forming a trench on a substrate,
A method for producing a superconducting junction, comprising the step of producing a superconductor on the substrate so that a superconducting junction is formed on the trench. 23. The method of making a superconducting junction of claim 22, wherein ion beam etching is used to make the trench. 24. The method of making a superconducting junction of claim 22, wherein reactive ion beam etching is used to make the trench. 25. The method of making a superconducting junction of claim 22, wherein reactive ion etching is used to make the trench. 26. The method for producing a superconducting junction according to claim 22, wherein plasma etching is used for producing the trench. 27. The method for producing a superconducting junction according to claim 22, wherein wet etching is used for producing the trench. 28. The method for producing a superconducting junction according to claim 22, wherein a lift-off method is used for producing the trench. 29. A step, which is formed on a substrate, and a superconducting thin film, which is formed on the substrate, wherein a portion of the superconducting thin film formed on the step portion of the step functions as a Josephson junction. A superconducting junction characterized by utilizing plane-orientation-dependent etching for manufacturing steps on a substrate. 30. The method for producing a superconducting junction according to claim 29, wherein a plane orientation dependent etching method using a solution containing KOH is used for producing the step. 31. The method for producing a superconducting junction according to claim 29, wherein a plane orientation dependent etching method using a solution containing NaOH is used for producing the step. 32. The method for producing a superconducting junction according to claim 29, wherein a plane orientation dependent etching method using a solution containing hydrazine is used for producing the step. 33. The method for producing a superconducting junction according to claim 29, wherein a plane orientation dependent etching method using a solution containing ethylenediamine is used for producing the step. 34. The method for producing a superconducting junction according to claim 29, wherein a plane orientation dependent etching method using a solution containing a quaternary ammonium hydroxide is used for producing the step. 35. The method for producing a superconducting junction according to claim 29, wherein a plane orientation dependent etching method using a solution containing KOH and 2-propanol is used for producing the step. 36. The method for producing a superconducting junction according to claim 29, wherein a plane orientation dependent etching method using a solution containing KOH and hydrazine is used for producing the step. 37. Hydrazine and H ₂ O for making steps
The method for producing a superconducting junction according to claim 29, characterized in that a plane-orientation-dependent etching method using a solution containing is used. 38. The method for producing a superconducting junction according to claim 29, wherein a plane orientation dependent etching method using a solution containing methylammonium hydroxide is used for producing the step. 39. NH ₄ F and Cu (N
30. The method for producing a superconducting junction according to claim 29, characterized in that a plane-orientation-dependent etching method using a solution containing O ₃ ) ₂ is used. 40. A superconducting junction composed of a substrate, a superconducting thin film formed on the substrate, and a superconducting junction portion of the superconducting thin film, wherein a protective film epitaxially formed on the superconducting thin film is provided. Characteristic superconducting junction. 41. As a superconducting thin film, Ba _1-x K _x BiO _{3 is used.}
41. The superconducting junction according to claim 40, wherein BaBiO ₃ is used as a protective film. 42. As a superconducting thin film, Ba _1-x K _x BiO _{3 is used.}
The superconducting junction according to claim 40, wherein BaPbO ₃ is used as a protective film. 43. In a superconducting junction composed of a substrate, a superconducting thin film formed on the substrate, and a superconducting junction part of the superconducting thin film, the superconducting thin film is epitaxially formed between the substrate and the superconducting thin film. A superconducting junction having a buffer layer that can be formed on the substrate. 44. Ba _1-x K _x BiO ₃ as a superconducting thin film
44. The superconducting junction according to claim 43, wherein BaBiO ₃ is used as a buffer layer. 45. As a superconducting thin film, Ba _1-x K _x BiO _{3 is used.}
44. The superconducting junction according to claim 43, characterized in that BaPbO ₃ is used as a buffer layer. 46. As a superconducting thin film, Ba _1-x K _x BiO _{3 is used.}
44. The superconducting junction according to claim 43, wherein MgO is used as the buffer layer and sapphire is used as the substrate. 47. A superconducting junction comprising a superconducting thin film, a superconducting junction portion of the superconducting thin film, and an electrode formed on the superconducting thin film, wherein an oxide thin film is used as the electrode. Joining. 48. In a superconducting junction constituted by a superconducting thin film, a superconducting junction portion of the superconducting thin film, and an electrode formed on the superconducting thin film, an oxide thin film is used as the electrode, and the superconducting thin film is formed. A superconducting junction characterized in that the electrode is formed in-situ after the film. 49. As a superconducting thin film, Ba _1-x K _x BiO ₃
48. The superconducting junction according to claim 47, wherein NbO is used as an electrode. 50. As a superconducting thin film, Ba _1-x K _x BiO _{3 is used.}
48. The superconducting junction according to claim 47, wherein NdO is used as an electrode. 51. As a superconducting thin film, Ba _1-x K _x BiO _{3 is used.}
48. The superconducting junction according to claim 47, wherein ReO ₃ is used as an electrode. 52. As a superconducting thin film, Ba _1-x K _x BiO _{3 is used.}
48. The superconducting junction according to claim 47, characterized in that RuO ₂ is used as an electrode. 53. As a superconducting thin film, Ba _1-x K _x BiO _{3 is used.}
48. The superconducting junction according to claim 47, characterized in that OsO ₂ is used as an electrode. 54. Ba _1-x K _x BiO ₃ as a superconducting thin film
48. The superconducting junction according to claim 47, characterized in that IrO ₂ is used as an electrode. 55. In a superconducting junction composed of a superconducting thin film and a superconducting junction part of the superconducting thin film, a Bi-based superconductor is used as the superconducting thin film, and an insulating material is obtained by changing a composition ratio of a part of the superconducting thin film. A superconducting junction characterized in that a region sandwiching this insulator portion is used as a superconducting junction. 56. As the superconducting thin film, BiSr (Ca,
56. The superconducting junction according to claim 55, characterized in that Y) CuO is used, an insulator is formed by using a composition with an excess of Y in a part thereof, and a region sandwiching the insulator portion is used as a superconducting junction. 57. BiSrCa (C) as a superconducting thin film
56. The superconducting material according to claim 55, characterized in that (u, Fe) O is used, and a composition with an excess of Fe is used as a part thereof to form an insulator, and a region sandwiching the insulator part is used as a superconducting junction. Joining. 58. In a superconducting junction comprising a superconducting thin film and a superconducting junction portion of the superconducting thin film, the superconducting thin film having a resistor thin film connected to the superconducting thin film, the superconducting thin film and the resistor thin film being arranged without overlapping. Then, the superconducting junction is characterized in that the superconducting thin film and the resistor thin film are connected by a low resistance metal thin film. 59. As a superconducting thin film, Ba _1-x K _x BiO _{3 is used.}
59. The superconducting junction according to claim 58, wherein TaN is used as the resistor thin film and Au is used as the low resistance metal thin film. 60. The superconducting junction according to claim 58, wherein the superconducting thin film is used as a microwave strip line, and the resistor thin film is used as a strip line terminator.