JPH0577316B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Application of the Invention The present invention relates to a method for manufacturing a solid-state electronic device using a ceramic superconducting (also referred to as superconducting) material.

The present invention relates to a method for manufacturing a four-terminal (including three-terminal) element having an input terminal and an output terminal. The present invention provides such an element with an amplifying function and a switching function, and also detects an output signal from the output by applying an input signal to a control input.

"Prior Art" Conventionally, attempts have been made to fabricate solid-state electronic devices using superconducting materials, such as metal materials such as Nb-Ge (Nb ₃ Ge, for example).

A typical example is the Josephson device. This Josephson element attempts to perform switching by combining superconductivity and tunnel current phenomena, and consists of a two-terminal circuit.

"Conventional Problems" However, since such a Josephson device is a two-terminal circuit device, the input signal and output signal cannot be used as independent signals. For this reason, when considering industrial applications, although it has the feature of being able to operate at ultra-high frequencies, circuit design is extremely difficult, and it is difficult to use the design technology that has been cultivated in conventional semiconductor integrated circuits. It has the disadvantage that it cannot.

In particular, since it is a two-terminal element, it does not have a signal amplification function, and the signal is attenuated slightly from the input end to the output end in the entire system, making it impossible to achieve a so-called gain of 1 or more. It has major drawbacks.

The present invention aims to eliminate such drawbacks, operate at very high frequencies, and provide a four-terminal circuit element, that is, a control electrode for applying an input signal and an electrode for deriving an output signal.

"Means to Solve the Problem" In order to solve the problem, the present invention provides a four-terminal solid-state electronic element (device) structure using superconducting ceramic material (ceramics).

In the present invention, a superconducting ceramic is provided on a substrate having a non-superconducting insulating surface, and a first superconducting ceramic having a finite resistance at an operating temperature is provided in a partial region thereof. A second superconducting ceramic having zero resistance is provided on one and the other of the ceramics.

Ceramics with finite resistance are made by adding impurities to superconducting ceramics, and the impurities weakly destroy the superconductivity. Furthermore, a control electrode is provided on the upper or lower surface of the first superconducting ceramic to control the current flowing therethrough. Between this control electrode and the ceramics, there is a coating that should prohibit the transfer of current.
In particular, an insulating film is provided.

In the present invention, the first superconducting ceramic having finite resistance uses the same components as the second superconducting ceramic having zero resistance, and impurities are added thereto by ion implantation or the like.

This impurity may be an element constituting the superconducting ceramic, such as Y (yttrium), copper (Cu), barium (Ba), or oxygen (O). Such impurities need to be added in large amounts to the extent that they disturb the chemical stoichiometric ratio that exhibits superconductivity. Specifically 5×
It is on the order of 10 ¹⁹ to 5×10 ²¹ cm ⁻³ .

In addition, other impurities include iron (Fe), nickel (Ni), cobalt (Co), silicon (Si), germanium (Ge), boron (B), aluminum (Al),
There is one or more types selected from galium (Ga), phosphorus (P), and arsenic (As). In such a case, the concentration of the impurity is between 5×10 ¹⁵ and 3×10 ²⁰ cm ^-3
And so.

In the superconducting element of the present invention, impurities are added to the second superconducting ceramic to form the first superconducting ceramic. This allows Tco
(the temperature at which resistance becomes zero) decreases, but Tc onset does not change much. As a result, the difference between Tc onset and Tco widens and can generally be greater than 10K.

Ceramic materials are more preferred for use in the device of the present invention than conventionally known metallic superconducting materials, which have a difference of only 1K or less.

The present invention has a sufficiently large electric resistance between electrodes connected between a pair of output superconducting ceramics.
Preferably the electrical resistance of the first superconducting material is 10
A coating having an electrical resistance more than double that is provided on the upper surface, lower surface, or both surfaces.

In the present invention, a film, preferably an insulating film, having an electrical resistance sufficiently higher than the electrical resistance of the superconducting ceramic is provided between the control electrode and the superconducting film, and a voltage is applied from the control electrode, which is an input terminal. Then, a voltage is applied to the superconducting ceramic underneath. This ceramic is produced in an intermediate state between completely superconducting and completely non-superconducting (partly superconducting and partially non-superconducting, that is, at a temperature between Tc onset and Tco). (region state), it is possible to change and control its own potential according to the voltage applied to the input control electrode.

The insulating properties of the coating interposed between the control electrode and the ceramic used in the present invention can be removed even if the current applied to the input signal can be ignored in terms of the mechanism. It is also possible to use a coating whose resistance is 10 times or less.

In the present invention, the superconducting ceramic has a control electrode as shown in FIG. 1A or B.
If there is only one layer, it is important to make it relatively thin, 0.01 to 10 μm, so that the potential can be changed even on the opposite side. In addition, when two control electrodes are provided above and below the ceramic as shown in FIG. 1C, the thickness may be 0.1 to 50 μm, which is about 5 times the thickness on average.

1A, B, and C show longitudinal cross-sectional views of the solid-state device of the present invention.

2 in Fig. 1 is superconducting ceramics 3,
5 uses characteristic 16 in characteristics 3 and 5 in FIG. With this characteristic, Tco28 has a resistance of zero or a value sufficiently close to zero at the operating temperature (liquid nitrogen temperature in this case) of the solid state element of the present invention.

In the present invention, a second superconducting ceramic is formed over the entire surface and photoetched into a desired shape.
Thereafter, impurities were selectively added only to this region in order to produce the first superconducting ceramic.
Only this region was made to have a Tco26 different from Tco28 of the second superconducting ceramic. The width of this impurity addition is 0.01 to 5μ, preferably 0.1 to 5μ
The length of the channel was made as short as possible, 1μ, using photolithography technology. The impurity by ion implantation is 5×10 ¹⁵ to 3×10 ²¹ cm ⁻³ and is implanted across the film in the depth direction. Furthermore, the whole was annealed in oxygen at 400 to 1000°C, for example 600°C, for 10 hours to oxidize the impurities and adjust the crystal structure. Thus,
First superconducting ceramic 4 in FIG.
For example, curve 4 of the temperature-specific resistance characteristics of superconducting ceramics in FIG. 3 is used. This uses the intermediate region between Tco 26 and Tc onset 25.

In FIG. 1A, a first superconducting ceramic 4 and a second superconducting ceramic 3 and 5 on a substrate 1 having a non-superconducting insulating surface are shown.
The ceramics 2 is made up of: A pair of output electrodes 8 and 9 (not shown in the drawing) may be provided at the left and right ends in the drawing. Further, a coating 11 is provided under the control electrode 10.

In FIG. 1A, the control electrode 10 is provided on the upper side of the first superconducting ceramic 4, and in FIG. 1B, it is provided on the lower side. In FIG. 1C, coatings are provided on both the upper and lower surfaces of the superconducting ceramic 4, and control electrodes 10 and 10' are provided, respectively.

In the manufacturing method shown in FIG. 1B, a control electrode is provided on a substrate having a non-superconducting surface, and a film having a sufficiently high electrical resistance is formed to cover this electrode. Next, a second superconducting ceramic is formed over the entire structure. Thereafter, only the upper surface of the control electrode is left, the rest is covered with a photomask, and impurities are added by ion implantation. After removing this photoresist, the entire structure is heated and oxidized in an oxygen atmosphere to form a first superconducting ceramic. The rest is the same as in FIG. 1A.

In FIG. 2C, after the structure shown in FIG. 2B has been formed, an insulating film is again formed on this ceramic, and another control electrode is provided.

"Operation" With such a structure, the input signal and the output signal can be controlled as independent functions, and this element can be used as a switching element or an element having an amplification function.

The present invention makes it possible to create a plurality of solid-state devices on the same substrate, and when trying to create a superconducting integrated circuit by connecting such devices based on design logic, the mutual wiring can be created with zero resistance. I can do it.

Examples will be described below with reference to the drawings.

Example 1 This embodiment shows the structure of FIG. 1A.

YSZ (yttrium stabilized zircon) was used as the substrate. This can be applied using the screen printing method, sputtering method, MBE (Molecular
Beam epitaxial) method, CVD (vapor phase reaction)
A superconducting material is formed using a method or the like. As an example of this superconducting material, (A _1-x Bx)yCuzOw, x=
0-1, y=2.0-4.0 preferably 2.5-3.5, z=
1 to 4, preferably 1.5 to 3.5, W=4 to 10, preferably 6 to 8. A is Y (Itztriyum),
Gu (Gadolinium), Yb (Itterbiyum),
Eu (europium), Tb (terubium), Dy
(dysprosium), Ho (holmium), Er (erbium), Tm (thulium), Lu (lutetium),
B selected from Sc (scandium) or one or more other elements in group a of the periodic table is Ra
(radium), Ba (barium), Sr (strontium), Ca (calcium), Mg (magnesium), Be (beryllium), group A of the periodic table of elements. Especially as a specific example (YBa ₂ )
_{Cu3O6-8 was} used _. Further, as A, a lanthanide element or an actinide element other than the above-mentioned elements in the periodic table of elements can be used. In addition, the periodic table of elements in the specification is from the Physical and Chemistry Dictionary (Iwanami Shoten April 1, 1963).
(Published on 2017).

Simultaneously with or after this formation, 600-1200℃
It was fabricated by thermal annealing at a temperature of 5 to 20 hours. In this way, properties 3 and 5 in Figure 3 could be obtained as a second superconducting ceramic.

Next, known photolithography is used. That is, in FIG. 1A, a photoresist is provided on regions 5 and 6, and impurities are selectively added only to region 4 where there is no resist by ion implantation. Impurities such as aluminum, silicon or iron are contained in an amount of 5×10 ¹⁵ to 3×10 ²¹ cm ^-3 , e.g. 5×10 ¹⁹
It was added to a concentration of cm ^-3 . After this, the photoresist is removed and aluminum is applied over the entire area.
Vacuum evaporation or light deposition to ~500Å, e.g. 100Å thickness
Formed by CVD method. Thereafter, the entire aluminum is oxidized in an oxidizing atmosphere at a temperature of about 400 to 1000 degrees Celsius, for example, 700 degrees Celsius, to form the aluminum oxide insulating film 11, and impurities added by ion implantation are oxidized to insulate the aluminum. transformed into a thing. As a result, as shown in FIG. 3, the Tco of region 4 was made to be only partially in the region of finite resistance with superconducting property 15.

It is effective to add this impurity by using the elements constituting the second superconducting ceramic, changing the values of x, y, z, and w, and performing the same process to obtain the first superconducting ceramic. Using such a method, Tc onset 25 was lowered below Tco'. Thus, curve 4 in Figure 3 was obtained.

Next, the control electrode 10 was manufactured using the same superconducting ceramic as the other second superconducting ceramic by the same method. The output electrode was placed in close contact with the ceramic thin film to make ohmic contact.

FIG. 2 shows the operation of this embodiment.

In this drawing, the horizontal axis indicates distance corresponding to FIG. 1, and the vertical axis indicates energy level (potential).

In FIG. 2A, a voltage is applied to the second superconducting ceramic, ie the other end 5 of the output. Then you will get a potential of 30. As a result, the electron is 2
0 and 20' exist in quantum theoretical wave nature, but since 20 is sufficiently larger, it is observed as 22 as a current.

In FIG. 2A, no voltage is applied to the control electrode.

In FIG. 2B, a negative voltage is applied to the control electrode. The potential 21 of the first superconducting ceramic, region 4, then moves from 24 in FIG. 2A to 24' in FIG. 2B. As a result, 20' becomes even smaller in relation to the formed barrier, and 20'
0 is extremely small because it is a barrier. Thus, when a voltage 30 is applied between the pair of output electrodes to cause a current 22' to flow from the region 3 of the second superconducting ceramic to the other region 5 of the second superconducting ceramic, the current is substantially It becomes difficult to flow and its value is suppressed.

As a result, current 22' becomes smaller when a negative voltage is applied to the control electrode.

Further, FIG. 2C shows the case where a positive voltage 21' is applied to the control electrode. The electron fiber probability 20' increases, and conversely 20 decreases. However, this well in region 4 is filled with electrons, and the barrier at 24'' virtually disappears after moving to the apparent potential at 25.As a result, a current 22'' equal to or close to that of Figure 2A flows. .

In this way, the output current can be detected based on the potential of the input signal. At this time, if the resistance of the film under the control electrode is sufficient and the output signal can be extracted larger than the energy structure for supplying the input signal, then the width has been increased, and it is a 4-terminal element and can be used as an amplifier. obtain. If you want to detect this output as a voltage, connect a resistor in series with the output as shown in Figure 2A.
If it is added as shown in the figure, the current can be detected as a voltage. In other words, an inverter can be made.

Although FIG. 3 has already been explained in connection with FIG.
Actual data of the first superconducting ceramic 4 and the second superconducting ceramics 3, 5 made to carry out the present invention are shown.

In the drawings, the horizontal axis represents absolute temperature (K), and the vertical axis represents specific resistance. This data measures up to 4.2K. However, as is clear from this drawing, in the first superconducting ceramic 4, the specific resistance gradually decreases at a temperature lower than the Tc onset at which superconductivity occurs, and the resistance becomes zero below the temperature Tco at which the resistance becomes zero. The 10% and 90% between this Tc onset and Tco are shown here as Tc ₁₀ and Tc ₉₀ . The superconducting element of the present invention may have any value between Tc onset and Tco, but it is preferable to use Tc ₁₀ and Tc ₉₀ in order to further stabilize the operation. Further, in order to increase the operating speed, it is preferable to use a characteristic between Tco and Tc ₁₀ .

Further, the second superconducting ceramics 3 and 5 similarly constitute the Tc onset 27 and Tco'28.

In FIG. 3, Tco26 can be varied by controlling the type and amount of impurities added to the material.

This data was highly reproducible when changing the temperature from a high temperature side to a low temperature side, and from a low temperature side to a high temperature side. The experiment of Example 1 was conducted at a liquid nitrogen temperature of 30°C.

"Effects" The present invention consists in changing the superconducting element, which has hitherto been a two-terminal element, to a four-terminal element. Under this control electrode, the potential changes with this electrode.
In order to provide a first superconducting ceramic that has a state intermediate between Tc onset and Tco over a wide temperature range, and to configure its electrodes and leads,
In such a temperature range, the interconnection is made of a second superconducting ceramic whose resistance is zero or sufficiently close to zero. In this way, it has become possible to amplify and control the output current according to the voltage of the control electrode.

Therefore, it has become possible to provide a large number of these superconducting solid-state devices on the same substrate and integrate them.

Although one control electrode is shown in the present invention, two or more control electrodes may be provided in series or in parallel.

In the present invention, a ceramic material was used as the superconducting material. However, as is clear from the technical concept of the present invention, any material having a wide temperature range between Tc and Tco, preferably 10〓 or more, does not need to be an oxide ceramic and can be selected arbitrarily. Needless to say.

In the present invention, the title superconducting ceramics is used. However, this is due to the fact that the superconducting material is an oxide. It is clear from the technical concept of the present invention that the crystal structure may be polycrystalline or single crystalline. In particular, in the case of a single crystal structure, when using a superconducting material, it is sufficient to epitaxially grow it on the substrate.

[Brief explanation of the drawing]

FIG. 1 shows a longitudinal cross-sectional view of a superconducting solid-state device of the present invention. FIG. 2 shows the operating principle of the superconducting solid state device of the present invention. FIG. 3 shows an example of the temperature characteristics of ceramics having superconducting properties used in the present invention.

Claims (1)

[Claims] 1. A step of forming an oxide superconducting material on a substrate having a non-superconducting surface, and selectively adding an impurity to a partial region of the oxide superconducting material to make the oxide superconducting material thinner. Low T _cp
and a step of forming a control electrode on the partial region, and the impurity is an element selected from the constituent elements of the oxide superconducting material, iron (Fe), nickel (Ni), etc. ), cobalt (Co), silicon (Si), germanium (Ge), boron (B), aluminum (Al),
The impurity is an element selected from gallium (Ga), phosphorus (P), and arsenic (As), and the impurity selected from the constituent elements of the oxide superconducting material has an additive concentration of 5×10 ¹⁹ to 5×10 ²¹ cm
^-3 , and the above-mentioned iron (Fe), nickel (Ni), cobalt (Co), silicon (Si), germanium (Ge), boron (B), aluminum (Al), gallium (Ga),
A method for producing a superconducting element, wherein the impurity selected from phosphorus (P) and arsenic (As) has an additive concentration of 5 x ¹⁰¹⁵ to 5 x ¹⁰²⁰ cm ^-3 . 2. A method for producing a superconducting element according to claim 1, characterized in that the control electrode is formed after forming a film covering the oxide superconducting material and having a sufficiently higher electrical resistance than the oxide superconducting material. 3. Forming a control electrode on a substrate having a non-superconducting surface; Forming an oxide superconducting material on the substrate and the electrode; and adding impurities to the oxide superconducting material on the control electrode. the impurity is an element selected from the constituent elements of the oxide superconducting material, or iron (Fe), nickel (Ni), cobalt ( Co), silicon (Si), germanium (Ge), boron (B), aluminum (Al),
The impurity is made of an element selected from gallium (Ga), phosphorus (P), and arsenic (As), and the impurity selected from the constituent elements of the oxide superconducting material has an additive concentration of 5×10 ¹⁹ to 5×10 ²¹ cm
The above iron (Fe), nickel (Ni), cobalt (Co), silicon (Si), germanium (Ge), boron (B), aluminum (Al), gallium (Ga),
A method for producing a superconducting element, wherein the impurity selected from phosphorus (P) and arsenic (As) has an additive concentration of 5 x ¹⁰¹⁵ to 5 x ¹⁰²⁰ cm ^-3 . 4. A method for manufacturing a superconducting element according to claim 3, characterized in that the oxide superconducting material is formed after forming a film having a sufficiently higher resistance than the oxide superconducting material on the control electrode.