JPH0634415B2 - Electronic device using oxide superconducting material - Google Patents

Description

The present invention relates to a fixed electronic device using an oxide superconducting material.

The present invention relates to a 3-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 applies an input signal to a control input to detect an output signal from the output.

“Prior art” Conventionally, superconducting materials such as Nb-Ge (for example, Nb ₃ G
Attempts have been made to make solid-state electronic devices using metallic materials such as e).

A typical example is the Josephson device. This Josephson element is intended to perform switching by combining a superconducting phenomenon and a tunnel current phenomenon, and is composed of a two-terminal circuit.

"Problems of the prior art" However, since such a Josephson element is a two-terminal circuit element, the input signal and the output signal cannot be used as independent signals and has no amplification function. Therefore, when considering industrial applications, circuit design is extremely difficult even though it has the feature that it can be operated at ultrahigh frequencies.
Further, there is a drawback that the design technology cultivated in the conventional semiconductor integrated circuits cannot be used.

Further, when the superconducting material is an oxide and a material used for a semiconductor integrated circuit, for example, a silicon semiconductor is brought into direct contact with it, the semiconductor itself reacts at its interface during long-term use, and a silicon oxide insulator grows, causing a current to flow. I will not let you flow. For this reason, no good means has hitherto been found for the method of contacting this semiconductor with the oxide superconducting material.

The present invention eliminates such drawbacks and provides an electrode for operating at a high frequency.

[Means for Solving Problems] In order to solve such problems, the present invention has a solid-state electronic device (device) structure in which an oxide superconducting material and a semiconductor material are combined.

The present invention, a semiconductor on a substrate having a non-superconducting insulating surface or a semiconductor constituting a semiconductor substrate, a superconducting material (Tco having a characteristic that the electrical resistance is zero or close to zero in the operating temperature region at both ends thereof. That is, the present invention relates to a solid-state element connected by a material having a temperature at which electric resistance is basically zero (this material is called an oxide superconducting material). Then, an electrode portion is provided in which this superconducting material is brought into contact with the semiconductor through an insulating or semi-insulating film having a thickness within a range in which a tunnel current flows.

In the superconducting element of the present invention, a semiconductor is provided on a pair of oxide superconducting materials via an insulating or semi-insulating film (hereinafter referred to as a tunnel current film) having a thickness that allows a tunnel current to flow. Further, this film for tunnel current contains silicon nitride or silicon carbide as a main component, has a blocking action against the reaction between the oxide superconducting material and the superconducting film, and is a material with a small energy band width in which a tunnel current easily flows. Was used.

Since this semiconductor has a depletion layer due to its applied voltage, a current flows between the electrodes of the superconducting material from one to the other depending on the size of the depletion layer.

1 (A), (B), and (C) are vertical sectional views of the solid-state device of the present invention.

In FIG. 1, a pair of oxide superconducting materials (3) and (5) are provided on an insulating substrate (1) having non-superconductivity. The semiconductor (4) is provided between them. The tunnel current films (8) and (9) of the present invention are provided at the contact portions (electrode portions) between the semiconductor (4) and the respective oxide superconducting materials.

In addition, a control electrode (1) is formed on the semiconductor (4) through an insulating film (11).
0) is provided.

In FIG. 1 (B), a field insulator (2) is selectively provided on a semiconductor substrate (1), and the electronic device of the present invention is provided therein. The tunnel current films (8) and (9) of the present invention are provided on the single crystal semiconductor substrate (1), and the electrodes of the oxide superconducting material and the leads (3) and (5) are closely attached to the films. Moreover, while covering these, an insulating film (11) is provided on the active region (4) of the semiconductor (1). Further, in FIG. 1 (C), which has a control electrode (10) on the insulating film (11) above the active semiconductor region (4), the single crystal semiconductor substrate (1) has an upper portion as shown in FIG. 1 (B). It has a field insulating film (2) similar to. In addition, the insulating film (11), which is located in the center of the internal semiconductor region surrounded by the field insulating film (2), is located at the center of the drawing and extends to the field insulating film in the direction perpendicular to the drawing. It has a control electrode (10) on it. The outer periphery of the control electrode (10) is covered with an insulating film (12) so that the electrode (10) and the oxide superconducting materials (3) and (5) are not short-circuited with each other. A tunnel current film (8), (9) is formed on the semiconductor without the control electrode and the insulating film below it.
Have. The oxide superconducting material (3),
The electrodes and leads of (5) are provided. This Figure 1
In (C), the self-junction type is used in which most of the impurity regions whose ends are aligned by the control electrode are in contact with the oxide superconducting material.

"Operation" With such a structure, the frequency characteristics are excellent, and the semiconductor material and the oxide superconducting material can be substantially brought into close contact with each other. Then, the respective materials do not react with each other, and an insulating film that promotes a decrease in reliability of progressive thickness is prevented from being formed at the interface so that an insulating tunnel current does not flow.

In the present invention, a non-oxidizing film containing silicon nitride and silicon carbide as main components is used as the tunnel current film. These are non-oxides, have a blocking effect on oxygen, and have a smaller energy band width than silicon oxide (silicon oxide 8eV, silicon nitride 5eV, silicon carbide 3eV),
It also has the feature that tunnel current can easily flow.

According to the present invention, a plurality of solid-state elements can be formed on the same substrate, and when the elements are connected based on the design logic to make a superconducting integrated circuit, interconnections thereof can be made with zero resistance. it can.

Embodiments will be described below with reference to the drawings.

Example 1 This example shows the structure of FIG. 1 (A).

YSZ (yttria stabilized zircon) or strontium titanate was used as the substrate. This is a superconducting material formed by screen printing, sputtering, MBE (Molecular Beam Epitaxial), CVD (vapor phase reaction), etc., such as (A _1-X Bx) yCuzO.
wx = 0.1 to 1, y = 2.0 to 4.0, preferably 2.5 to 3.5, z =
1.0 to 4.0, preferably 1.5 to 3.5, w = 4.0 to 10.0, preferably 6 to 8, A is Y (yttrium), Gu (gadolinium), Yb (ytterbium), Eu (europium), Tb (terbium), Dy (dysprosium), Ho (holmium), Er (
Erbium), Tm (thulium), Lu (lutetium), Sc (scandium) or other element selected from one or more kinds of group IIIa of the periodic table, B is Ra (radium), Ba (barium), Sr (strontium) ), Ca (calcium), Mg (magnesium), Be (beryllium), a superconducting material selected from one or more of the group IIa of the periodic table, especially YBa _{2
Cu 3 O 6 ~ 8, YBaSrCu} 3 O 6 ~ 8, it is YBaCaCu ₃ O ₆ ~ ₈ like. As A, a lanthanide element or an actinide element in the periodic table can be used. Further, silicon, germanium, tin, lead, indium, antimony, fluorine or the like may be added to these to lower the barrier of the grain boundary. In addition, the periodic table of elements in this specification is a dictionary of physics and chemistry (Iwanami Shoten, April 1963 1
Issued daily).

Simultaneously with or after this formation, thermal annealing was performed at a temperature of 500 to 1200 ° C. for 5 to 10 hours, and then gradually cooled.

Furthermore, a non-single crystal semiconductor (4) with hydrogen or a halogen element added to the upper surface of these is subjected to optical CVD or plasma CVD.
Formed by the method. The active semiconductor (4) region is created by leaving only the oxide superconducting materials (3) and (5) between them, and an insulating film is formed over them.
(11) was prepared, and the control electrode (10) was prepared thereon.

Next, the control electrode (10) was produced by using a vacuum evaporation method with an oxide superconducting material or a metal, such as copper or a compound of copper and nickel, which constitutes the second surface. Output end (1
8) and (19) were designed to be in close contact with the oxide superconducting thin film and eliminate the contact of zero resistance.

FIG. 2 shows the operation in this embodiment.

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

In Fig. 2 (A), the superconducting material, that is, the other end of the output (5)
Voltage is applied to. Then you get the potential (30). As a result, the electron exists in both (20) and (20 ') in quantum wave nature, but (20) is sufficiently large, so it is observed as (22) as a current.

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

In FIG. 2 (B), a negative voltage is applied to the control electrode. Then, the potential (21) of the active semiconductor region (4) shifts from (24) in FIG. 2 (A) to (24 ') in FIG. 2 (B).
In relation to the resulting barrier, (20 ') is smaller and (20) is extremely small because of the barrier. Thus, when a voltage (30) is applied between the pair of output electrodes from the region (3) of oxide superconducting material to the region (5) of another oxide superconducting material, the current (22 ') is flown: Virtually no current flows, and its value is suppressed.

As a result, when a negative voltage is applied to the control electrode, the current (2
2 ') becomes smaller.

Further, FIG. 2 (C) shows a case where a positive voltage (21 ') is applied to the control electrode. The electron transition probability (20 ') becomes large, and conversely (20) becomes small. However, the well in this region (4) is filled with electrons, and the barrier at (24 ″) virtually disappears after moving to the apparent potential at (25). As a result, it is the same as in FIG. 2 (A). Or a current (22 ″) close to it flows.

Thus, the output current can be detected by the potential of the input signal. At this time, the resistance of the film under the control electrode is sufficient,
If the output signal can be taken out larger than the energy structure for providing the input signal, it means amplification.
It is a terminal element and can be an amplifier. If this output is to be detected as a voltage, this output is connected in series with a second resistor.
If added as shown in Figure (A), it can be detected as voltage from the current. That is, an inverter can be made.

[Embodiment 2] FIG. 1 (B) shows another embodiment of the present invention.

In the drawing, a field insulating film (2) is selectively provided on a silicon semiconductor substrate (1). The semiconductor active region (4) is surrounded by this field insulating film, and the electrode leads (3), (5) of the oxide superconducting material are provided at both ends with the tunnel current films (8), (9) interposed. ) Is provided.

An insulating film (11), for example, a silicon oxide film is provided so as to cover all of them. A control electrode on this insulating film and on the active semiconductor region
Have (10).

Thus, one superconducting material (5)
In (3), the amount of current flowing through the active semiconductor region was controlled by the voltage applied to the control electrode (10).

In this figure, for the tunnel current films (8) and (9), the silicon semiconductor substrate (1) was heated in high-purity ammonia at 700 to 950 ° C. for 15 to 40 minutes. Then, the surface of this silicon semiconductor could be transformed into a silicon nitride film with a thickness of 10 to 25 Å. Since this silicon nitride film is formed at a high temperature and its temperature is almost the same as the temperature at which the oxide superconducting material is formed, it has a drawback that it reacts with the base at the same time when the oxide superconducting material is formed on its upper surface. I don't. Also in this example, the oxide superconducting material was the same as in Example 1.

"Embodiment 3" FIG. 1 (C) shows another embodiment of the present invention.

In the drawing, a feed insulating film (2) was formed on a silicon semiconductor as in FIG. 1 (B). After that, an insulating film (11) was made of a thermal oxide film on these. Further, the control electrode (10) was formed of an oxide superconducting material, a silicon semiconductor or a metal oxide. Further, these were patterned to form a control electrode and an insulating film thereunder, and the other part was removed.

Next, a large amount of P or N type additive is added to the semiconductor by ion implantation or the like using the control electrode or the photoresist on the mask as a mask to form impurity regions (13) and (14).

It has the same effect as the source and drain in the insulating gate type field effect semiconductor device.

An insulator was formed on the outside of the control electrode, and the tunnel current coatings (8) and (9) were made of silicon carbide. This production method is performed in an impurity gas containing high-purity methane gas at 800 to 10
The silicon semiconductor surface was carbonized by heating to 50 ° C. Thus, a semi-insulating silicon carbide film having a thickness of 10 to 30 Å was formed as a tunnel current film. The impurities added at the same time were annealed to make these regions (13) and (14) semiconductors of P or N type. The impurity concentration is 1 × 10 ¹⁹ to 1 × 10 ²¹ cm ^-3
And high concentration.

Further, to these, the same oxide superconducting material as in the example was formed by the sputtering method or the electron beam evaporation method, and the desired patterning was performed to prepare a pair of electrode leads (3) and (5) of the oxide superconducting material. did.

Leads (18), (19) for external contact may be provided on the outer side. Furthermore, after producing a superconducting material for the first layer as an oxide superconducting material, covering the entire surface of these with an insulating film and making holes at predetermined positions, as an oxide superconducting material as the oxide for the second layer. Good.

Thus, by setting the distance between the pair of superconducting materials under the control electrode (the length of the active semiconductor region) to be 1 μm or less,
A frequency characteristic of 1 ns or less can be expected.

In FIG. 1 (C), electrode leads made of an oxide superconducting material were formed on almost all of the impurity regions provided in the semiconductor via a tunnel current film. Thus, by making the impurity region smaller by an industrially possible method, a higher density integrated circuit can be obtained.

"Effect" The present invention prevents the oxide and the semiconductor from reacting with each other to form an insulating film at the interface so far, and a contact with a semiconductor of a so-called superconducting material is produced with high reliability. . In particular, if the semiconductor is single crystal silicon, it is possible to fabricate a VLSI with a lead having zero resistance.

INDUSTRIAL APPLICABILITY The present invention can be used for an electrode portion of a MIS type insulated gate field effect semiconductor device bipolar type semiconductor device.

Furthermore, many superconducting solid-state elements are provided on the same substrate,
It became possible to integrate.

In the present invention, by using the tunnel current coating on the interface between the semiconductor and the superconducting material, an active element having sufficient reliability could be manufactured without lowering frequency characteristics. A P ⁺ or N ⁺ conductive type semiconductor device may be provided under the tunnel current coating by an ion implantation method or the like.

[Brief description of drawings]

 FIG. 1 shows a vertical sectional view of a superconducting solid-state element of the present invention. FIG. 2 shows the operating principle of the superconducting solid state element of the present invention.

Claims (3)

[Claims] 1. A semiconductor substrate, and a pair of oxide superconducting materials provided on the semiconductor substrate via a blocking layer.
An electronic device using an oxide superconducting material, comprising: an electrode for applying a voltage to the semiconductor substrate between the pair of oxide superconducting materials. 2. An electronic device using an oxide superconducting material according to claim 1, wherein silicon nitride or silicon carbide is used as a blocking layer. 3. An electronic device using an oxide superconducting material according to claim 1, wherein a non-oxide is used as the blocking layer.