JPS586188A - Josephson junction element - Google Patents

Abstract

PURPOSE:To prevent the deterioration of electric characteristics of the titled element due to heat cycle and variation for hour by a method wherein a junction layer, which generates superconductive tunnel effect between the first electrode material, consisting of the first and the second superconductive materials, and the second electrode material. CONSTITUTION:The first electrode material is formed with the first superconductive material 31 and the second superconductive material 32, which was arranged adjoining to the first superconductive material 31 having the depth of magnetic infiltration in superconductive state less than that of the first superconductive materia 31. Then, a junction layer 13, which generates a superconductive tunnel effect between the second electrode material 33 consisting of a niobe or niobic compound or a vanadium compound, and the first electrode material 31, is formed.

Description

[Detailed Description of the Invention] The present invention (q) is based on the structure of a Joseph Sono folded metal element used in a logic circuit or a storage device, a small magnetic field measurement element, a voltage IIA Hayabusa, etc. be.

The conventionally developed junction elements are made of lead alloy/
The main materials were those with a lead alloy oxide/metallic structure.

However, these lead alloy-based junction elements are
The bond is easily destroyed (and the characteristics deteriorate quickly) due to thermal cycles between the liquid helium temperature, which is the operating temperature, and the WI/i temperature. The deterioration of characteristics due to changes hardly occurs, and as a sefsonojo Kin Takuko, a niobium or niobium compound that is mechanically harder than lead is used as an electromagnetic material.
Son junction devices are being developed. Tokairin et al. reported in the Institute of Electronics and Communication Engineers technical research report CPM8G-90 (1
Published on February 17, 1981) K is stated. This ji,
Amorphous silicon and its oxide are used for the bonding layer of the Cefun junction element.

Niobium has five special properties: it has a very strong gelling effect and easily absorbs oxygen and various substances. Therefore, when niobium is used as the electrical component of a Josephson element, there is a phenomenon in which oxygen, etc. diffuses into the niobium electrode body during the formation of the bonding layer, and oxygen, etc. in the bonding layer similarly diffuses after the bonding layer is formed. te1
1! It has the disadvantage that it easily diffuses into the niobium of the bridge body.

For this reason, a gap occurred in which the thickness of the welding layer was extremely unstable. The thickness of the bonding layer of a di-, sen-junction device greatly affects the electrical characteristics of the device, so it is necessary to control the thickness of the bonding layer to a few percent or less. It was difficult to control the thickness of this bonding layer with the di-1-seven bonding element used.
Rounding, where the equivalent thickness of the bonding layer changes over time;
The disadvantage is that the electrical characteristics of the element deteriorate.

On the other hand, niobide metals such as niobium nitride are characterized by the fact that niobium has already been crystallized as a compound with nitrogen, etc., so the gelling effect is significantly reduced, and the adsorption of oxygen and diffusion into the compound is significantly reduced. There is. Therefore, the niobium compound has five advantages in forming the welding layer: the thickness can be easily controlled and changes over time are reduced. However, in niobium nitride and other 10-niog compounds, the depth of magnetic field penetration in the superconducting state is 400 to 500 nanometers, which is 4 to 5 times larger than that of niobium, so the kinetics and tie/clampance increase, resulting in signal transfer. There are five drawbacks: as the time increases, the magnetic field sensitivity decreases.

In order to use this niobium nitride as an electrode body and eliminate the drawback of 9 o'clock, a two-layer layer of niobium nitride and niobium was used as a base electrode ((jl
The structure of a Josephson junction element with a lead alloy electrode (electrode body) and a lead alloy electrode (electrode body of medicine 2) was shown by the middle plate, etc., in the pre-tachibana collection of the @28fg Applied Materials Weir Science Association Lecture. 4
It is stated on page 44 (-No. 29P-LJ-12)K. However, since lead is used for the capacitor electrode (second electrode body) K of this electrically injected junction element, the disadvantage of deterioration of the electrical characteristics of the element due to thermal cycles and changes over time as described above is eliminated. , not completely eliminated.

It is an object of the present invention to provide a Josephson junction element which exhibits less deterioration of the electrical characteristics of the element due to thermal cycles and changes over time, and which is fast and has good magnetic field sensitivity.

According to the present invention, in the first superconductor and the superconducting state, the penetration depth of the O magnetic field is smaller than that of the first superconductor.
#11 electric body made of the 20th superconductor disposed in contact with the superconductor; a second electric body made of niobium or a niobium compound or a vanadium compound; A superconducting tunnel effect is produced through the intervening superconductor and the #2 osgi body.
A Josephson junction element is obtained, which is characterized in that it is composed of a junction layer.

More books! According to the invention, the aforementioned Joseph Sono metal element is obtained, characterized in that a niobium compound is used as the first superconductor and niobium is used as the 20th superconductor.

Further, according to the present invention, there is provided the aforementioned O-Cefson junction element, characterized in that silicon nitride, silicon oxide, or Si% I:I and silicon oxide is used as the contact layer.

The following figures illustrate the present invention and the pancreatic beak.

FIG. 1 shows the structure of a conventional di- and hepson junction element. A lead alloy, niobium, a niobium compound, or the like is used for the electrode body 11 and the second electrode body 12 of dl. For the 1a composite layer 13, an oxide layer of the first T-tree 11 or an insulator such as amorphous silicon and its oxide or niobium nitride is usually used. a first electric body 11;
The insulating layer 14 that insulates the second electric machine body 12 includes 8i0
Silene oxides such as 8 & 0° are commonly used.

FIG. 2 shows the structure of a conventional Josephson junction device having the aforementioned ninety-two layer expanded base electrode structure. 1st
The electrode body is composed of electrified niobium 1II 21 and niobium film 22. A lead alloy is used for the electrode body 12 of g2, amorphous silicon and its oxide is used for the bonding layer 13, and a silicon oxide film is used for the insulating layer 14. By setting the thickness of the niobium film 22 to 300 nanometers and the thickness of the electrified niobium 51I21401 to 60 nanometers, the depth of magnetic field penetration is 1/4 of 100 nanometers.
~115, significantly improving the magnetic field sensitivity. However, since a lead alloy is used for the 20th electrode body 12, the drawback that the electrical characteristics of the element deteriorate due to thermal cycles and changes over time cannot be eliminated. Both figures show the control lines that control the switching of the Ji, Sen, and Seven table elements, and the ground plane. Additional functional units for practical use, such as those in the III layer, have been omitted to simplify the explanation. 'ls3 Figure is @10
This shows an example. Similar to Figures 1 and 2,
Some of the rounding devices for control lines, ground planes, etc. are omitted. Bonding layer 13 and insulating layer 1 of Ki 10 Yoshikoji example
4 and 2 are the same as the prior art of FIG. 1 and FIG. 2, so they are indicated by the same numbers. The difference between the present invention and the first intention is that No. 20 @ Integral 33 is made of a vanadicum compound instead of a niobium or wire niobium alloy. This has solved the problem of deterioration caused by the use of lead alloys. Although niobium compounds tend to deteriorate due to heat and carbonization over time, they are inferior to lead-based compounds in terms of device electrical characteristics. However, by forming the first electrode body with two layers, it is possible to suppress signal transfer delay and decrease in magnetic field sensitivity. Therefore, it is possible to realize a diode junction element in which signal transfer delay is small, magnetic field sensitivity is less likely to decrease, and deterioration hardly occurs. The first electrode body of the present invention includes a first superconductor 31 made of a niobium compound, etc., and an 80th superconductor 31 made of niobium or the like, in which the penetration depth of the magnetic field in the superconducting state is smaller than that of the first conductor 31. The #I2O electric bridge body 33 made of niobium, a niobium compound, or a vanadium compound and the first superconductor 31 of the first electric body are nitrided. A bonding layer 13 made of silicon, an oxide of silicon, or an oxide of amorphous silicon and silicon is arranged with a mortar, and the bonding layer 13
1C causes a superconducting tunnel effect.

The 1llll superconductor 31 of the electrode body of lsl is the bonding layer 1
For the formation and aging of 3, the tI &! of the first electrode body.
The bonding layer 13 is formed to have a sufficient thickness so as not to be affected by the above-mentioned oxygen amplification force due to the interaction between the superconductor 32 and the bonding layer 13. The second superconductor 32 of the first electrode body and the first layer electrode 1i33 are formed to have a thickness that is at least greater than the depth of magnetic field penetration in the superconducting state, and has an appropriate thickness that allows for back-penetration. be done. Therefore, the depth of magnetic field penetration in the equivalent superconducting layer of the fsl electrode body is comparable to that of the second superconductor, and the signal transfer delay and magnetic field sensitivity decrease due to the aforementioned kinetic inductance. is prevented. In the Joseon/element of the present invention, since niobium, a niobium compound, or a vanadium compound made of a mechanically hard metal or metal compound is used as the second electrode body 33, deterioration due to changes over time is extremely reduced. can. However, when Niogide gold is used as the second electrical body, the depth of magnetic field penetration is O, which is smaller than that of lead or Niogide.
The electrical characteristics of the element are more exposed than in a round pigeon coop using lead or niobium.

Next, a method for manufacturing the Josephson element of the first embodiment will be briefly described. First, one layer of the la2 superconductor 32 of the allt2) electrode body is formed using a vapor deposition or sputtering technique, and then the jlilo superconductor 31 of the 'sl electrode body is formed.
(The 0 layer is formed using the same technique as described above. After patterning the first electrical body by lift-off technique etc.,
As the layer of the insulating layer 14, ago.

A film of silicon O oxide such as 810, etc. is formed using a vapor deposition technique, chemical vapor deposition, y-technique 1f (referred to as CVD technique), and then buttered by a lift-off technique or the like. As the bonding layer 130, amorphous silicon/silicon nitride or the like is formed using CVD technology. Also, as another method for forming the bonding layer 13,
There is a method of anodic oxidation of a part or the whole of amorphous silicon formed by CVD technology to form a silicon oxide. A film of a niobium or niobium compound, etc., which will become the second electrode body, is then formed by a sputtering technique, a vapor deposition technique, or the like. The second electric bridge body is patterned using a seven-toff technique or the like. At this time, a bonding layer 13 is formed on the insulating layer 14.
At the same time when forming this layer, the same material 34 as the bonding layer remains, but since it is an essential material similar to the insulating layer 14, it does not affect the electrical characteristics of the device.

@4111d shows the structure of a di-, sen-junction element according to a second embodiment of the present invention. Since the basic structure of the element welding sO is the same as that of the first embodiment, gtos
The same effect as in the example can be obtained. However, the manufacturing procedure is different and the overall structure is interesting.

ing.

The diode junction device of the second embodiment is manufactured by the following procedure. First, the second superconductor 42 of the 1M1 electrode body
However, a film was formed using the example of Yuki I and P44m, and an electrode body of mJl was patterned. Next, the rim layer 14 is the first layer.
A film is formed and patterned in the same manner as in Example 2. After that, 410 layers of @10m11i type superconductor are deposited using the circle technique described above, and then the bonding layer 130 layer and the second electrode body 43 layer are deposited sequentially from 9mIIK as described above. .

Finally, the second electrode body is patterned using techniques similar to those described above. At this time, a layer 45 of the same material as the JIO superconductor of the first electrical bridge body and a layer 45 of the same material as the bonding layer are simultaneously patterned and remain on the insulating layer 14.

The second embodiment is characterized in that the first superconductor 41, bonding layer 13, and second electric bridge body of the 101st fiber can be made in series without destroying the vacuum of the back passage device. be. Therefore,
Since the element is manufactured without contaminating the surfaces between the superconductor 41 of the first electric bridge body, the metal layer 13, and the second electric bridge body 43 with oxygen in the air, etc. , good quality ji,
There is an advantage that a cefn/junction element can be obtained. however,
There is a drawback that the superconductor 0 layer 45 of JGL and the #II layer 44, which is the same as the bonding layer, remain on the insulating layer 14. However, mJl[141e)M1eMffllllノ445
B. It is insulated from the first electrode body by the insulating layer 14, and the layer 44 made of the same material as the bonding layer is the same insulator as the insulating layer 14, so both have no effect on the electrical characteristics of the element. It has no effect.

FIG. 5 shows the structure of a di-cefsol element according to an embodiment of the present invention. Since the basic structure of the contact portion of the element is the same as that of the first embodiment and the second embodiment, the same effects as the first embodiment and the second embodiment can be obtained. Since the manufacturing method is different, the structure of the first superconductor 510 layer and the bonding layer 13 of the 10th electrode body is different from the fil example and the 20th example.

Third Example Ji, Sehun/JjiI! The composite element is manufactured by the following procedure. First, the second superconductor 52 of the #11 electrode body is formed into a film and patterned in the same manner as in the second embodiment. The slit layer 14 is formed and patterned in the same manner as described above. Next, J of ill electric bridge body
The superconductor 51, the bonding layer 13, and a part of the layer 53 of the second electrode body are sequentially formed using the same technique as described above. Here, the pattern of the bonding layer 13 is patterned using a lift-off technique or the like. At this time, the tenth superconductor 51 of the ill electric bridge body and part of the layer 53 of the second electrode body are patterned at the same time. Therefore, no film corresponding to the first superconductor s1 of the first electrode body and the bonding layer 13 remains on the insulating layer 14, and finally the remaining portion 54 of the electric bridge body of 1 tuna 2 is left on the insulating layer 14. The film is formed using the same technique as described above, and the second electrode body is patterned using the same technique as described above.

In the third embodiment, the vacuum is broken between the first superconductor 51 of the first 11L body forming a di-Sefson junction, the bonding layer 13, and the part 53 of the tank body. It has the feature that only the joint pattern part can be made in KIN. Therefore, the third embodiment has the advantages of the second embodiment and the insulating layer 14.
This has the advantage that the electrical characteristics of the device are more stable because no unnecessary patterns are left on top.

The details of the manufacturing procedure of each of the above-mentioned embodiments and the manufacturing method of additional functional parts such as ground planes and control lines that are necessary for practical use are provided by Dan Ina (J, H6Qt@in@r) at IB. Journal of Engineering (IBM Jural)
of R@5earch and Developopa
x*nt) 1m24% No. 2, pages 195 to 20
It is described in detail in 5.

As described above, according to the present invention, it is possible to obtain a Josephson junction element that exhibits less deterioration due to thermal cycles and changes over time (high speed and good magnetic field sensitivity OIL).

[Brief explanation of drawings]

Figure #E1 shows the structure of a conventional di-junction element, and Fig. 2 shows a conventional di-silicon junction device with a two-layer membrane base electrode structure.
Cefso/! Figure 13 shows the structure of the Josey yyy@gold element of the first embodiment of the present invention, and Figure 4 shows the Joseph Sono element of the embodiment of the present invention @0712. FIG. 5 shows the structure of a Joseph sono contact element according to a third embodiment of the present invention. 11... I@l electrode body, 12... second electrode body,
13-... Welding layer, 14... Insulating layer, 21, 31, 4
1゜51...109th conductor of 10m1j body, 22
゜32.42.52... superconductor of rattan 2 of the first electrode body, 33.43... second electrode body, 34.44- superconductor of the same material as the bonding layer remaining on the insulating layer Layer, 45... The first (D superconductor, s3... part of the second electrical unit remaining on the insulating layer, 9 parts that are simultaneously attached to the bonding layer, 54
...The remaining one minute of the second electrode body is used as the second electrode body and is buttered for 9 times. Figure 1 Figure 2 Figure 3 Figure 3 Figure 4

Claims (1)

[Scope of Claims] 1) A second superconductor disposed in contact with the first O superconductor, in which the depth of magnetic field penetration between the first superconductor and the superconductor is smaller than that of the first superconductor. a first electric body made of a superconductor; a second electrode body made of niobium, a niobium compound, or a vanadium compound; the first superconductor and the second electrode body of the first electrode body; 1. A junction element comprising: a junction layer that is interposed between a conductive layer and a junction layer that produces a superconducting tunnel effect; 2) A niobium compound is used as the first superconductor, and niobium is used as the $2 superconductor. Junction element. 3) A Josephson post-gold device implanted in paragraphs 1 and 2 of box OII, characterized in that the bonding layer is electrified silicon, an oxide of silicon, or an oxide of silicon and silicon.