JPH0680741B2 - Superconductor device - Google Patents

Description

TECHNICAL FIELD The present invention relates to a superconductor device using a ceramic superconducting material. The present invention is particularly applicable to a superconductor device, in which a part or all of interconnections of a semiconductor device is formed of a superconducting material. Therefore, an insulating film for blocking is provided in close contact with electrodes and leads of the superconducting device, and between the semiconductor and the semiconductor. Silicon oxide, silicon nitride, or a film containing them as a main component is formed on the above, and a conductive film for blocking is simultaneously provided in the electrode portion of the semiconductor, and a stable semiconductor device is provided at 70 to 100 k, preferably 77
It is intended to operate at temperatures above K.

"Background of the Invention" Conventionally, ultra-electric material using Nb-Ge system (eg Nb ₃ Ge) metal material such as wires, have been limited to use as a super electric magnet.

It has also been recently known that ceramic materials can exhibit superconductivity. However, this is also an ingot structure, and formation of a thin film superconducting material has not been proposed at all.

In other words, there is no known method of patterning this thin film by photolithography, and its use as a part of interconnection of a semiconductor device.

“Conventional Problems” In recent years, semiconductor integrated circuits have become more and more miniaturized and are required to operate at high speed. Further, along with the miniaturization, there has been a problem that reliability is deteriorated due to heat generation of the semiconductor element and operation speed of the heat generating portion is decreased.

Therefore, if the semiconductor device is operated at the liquid nitrogen temperature, the mobility of electrons and holes in the device can be increased by 3 to 4 times as much as that at room temperature, and the frequency characteristic of the device is improved. it can.

In order to solve such a problem, there has been an attempt to use a superconducting material of a ceramic material as a lead wire in a superconductor semiconductor device. However, since such oxide ceramic superconducting material uses Ba (barium), which has an extremely large ionization tendency, it reacts with them and silicon oxide, silicon nitride, or an insulating film containing them as a main component and the oxide superconducting material are separated. The integrated circuit cannot be configured as a lead or the like in close contact with each other.

[Means for Solving Problems] In order to solve such problems, the present invention uses an oxide superconducting ceramic material that exhibits superconductivity at extremely low temperatures (20-100 k, preferably 77 k or higher) for interconnections in semiconductor devices. It is a thing. At that time, a so-called blocking material for preventing mutual acid-base reaction is interposed between the material on the lower surface of the material and the substrate material or silicon oxide or silicon nitride on the substrate.

This blocking material is zirconium oxide, YSZ (yttrium stabilized zircon), strontium titanate, a non-superconducting material whose main component is the same as the oxide superconducting material, for example, a non-superconducting oxide containing 5 to 10% by volume of aluminum or magnesium. It is composed of a ceramic material or a multilayer film thereof (for example, a film having a zirconium oxide film on a base silicon oxide film, an oxide non-superconducting ceramics further thereon, and an oxide superconducting ceramic material structure on top thereof).

The present invention uses a semiconductor in which these blocking films are formed to a thickness of 0.1 to 10 μm, particularly preferably a semiconductor having heat resistance, for example, a single crystal silicon semiconductor substrate, and a plurality of elements such as an insulating gate Type field effect transistor, bipolar type transistor, SIT (static induction type transistor), resistor, capacitor. Then, silicon oxide, silicon nitride, or an insulating film containing these as a main component, which is generally used as a passivation film on the semiconductor substrate, is provided in a region other than the contact opening. In the present invention, a coating film containing an insulating film having a blocking action as a main component is provided on these insulating films, and an oxide superconducting material having an electric resistance of zero or close to zero is formed thereon.
This is subjected to selective etching by photolithography and patterned to act as a lead or the like. When a hybrid method is used for this etching, an acidic solution may be used. When the vapor phase method is used, anisotropic plasma etching using bromine or chlorine is performed. Further, by performing thermal annealing at 500 to 1000 ° C. before or after the step for a long time of 1 to 20 hours particularly in an oxidizing atmosphere of oxygen, active oxygen, etc., the crystal of the ceramic material is made to exhibit the superconducting phenomenon at an extremely low temperature. Modify the structure. By repeating these steps once or a plurality of times, one layer or interconnections of each layer are formed of a material having an electric resistance of zero.

"Operation" Thus, the oxide superconducting material could be used for some or all of the leads of the semiconductor device. And semiconductor element,
In particular, by forming a blocking layer between an insulating material containing silicon, such as silicon oxide or silicon nitride, which is widely used for silicon semiconductor elements, and the oxide superconducting material so that they do not come into direct contact with each other, the characteristics of the oxide superconducting material are improved. It was possible to withstand and prevent the reaction with the underlying material even by thermal annealing at 500-1000 ℃ for improvement.

When such a semiconductor device is operated at the liquid nitrogen temperature, its electron or hole mobility can be improved 3 to 4 times. In addition, the electric resistance of the leads and electrodes can be made zero or equal to zero. The R (resistance) in the CR time constant indicating the delay of the frequency characteristic can be set to zero, which enables extremely high speed operation.

Embodiments of the present invention will be described below with reference to the drawings.

Example 1 FIG. 1 shows an example of a manufacturing process of a superconducting semiconductor device of the present invention.

In FIG. 1 (A), a silicon oxide insulating film (2-1) is formed on a silicon semiconductor substrate (1).

In the semiconductor substrate (1) shown in FIG.
An (insulated gate type semiconductor device), an active type element such as a bipolar transistor or a passive type element such as a resistor and a capacitor are provided in advance. These active-type or passive-type elements are provided, and an impurity region for connecting with a contact of such an element is provided on the semiconductor. An opening (8) is formed in a part of the insulating film on the impurity region. In the embodiment of the present invention, silicon oxide of 0.3 μm is formed on the semiconductor as an insulating film.
Formed to a thickness of. Then, contact holes (openings) for electrodes were formed in the silicon oxide film at predetermined positions by photoetching. Therefore, the insulating film (2-1), (2-
The openings of 2) were formed at the same position and with the same size. Further, zirconium oxide, which is a blocking insulating film (2-2) for acid-base reaction, is sputtered on the upper surface of these for 0.1 to 2
The thickness is, for example, 0.4 μm. Then, in the insulating film (2) having these multilayer structures, the electrode contact portion serves as the electrode port (8) described above.

Further, in FIG. 1 (A), a conductive film for blocking (21) is provided over the insulating film for blocking so as to prevent acid-base reaction between the oxide superconducting ceramics and the semiconductor in the opening (8). Has been.

In FIG. 1 (B), a material (3) which should exhibit superconductivity is formed in a thin film on the upper surface thereof. This thin film was formed by the sputtering method. It may be carried out by a screen printing method, a vacuum vapor deposition method or a vapor phase method (CVD method), particularly a magnetic field vapor phase method.

The formed oxide superconducting material is a compound composed of IIa and IIIa of the periodic table of elements and an oxide of copper, and the chemical formula of the formed oxide superconducting material is generally (A _1-X Bx) CuzOw, x =
0.1-1, y = 2-4, preferably 2.5-3.5, z = 1.0-4.0, preferably 1.5-3.5, w = 4.0-1.0, preferably 6-8. As A, Ba, Sr, Ca, and as B, a lanthanoid element such as Y or Yb is used. For example, x = 0.67, y = 3, z = 3, w = 6
Represented by 8 with _{(YBa 2) Cu 3 O 6} ~ 8.

As an example of the sputtering, the substrate temperature is 450
C., argon atmosphere, frequency 50 Hz, output 100 W.
In this case, the thickness of the ceramic material is 0.2 to 2 μm, for example, 1 μm. After that, annealing was performed in oxygen at 700 ° C. (10 hours). Then, the oxide superconducting ceramics (3) and the silicon oxide (2-1) preliminarily formed below the zirconium oxide (2-2) functioned as a blocking material, and the reaction could be prevented. By the way, it was revealed by Auger spectroscopy that the silicon oxide and the thin film of superconducting ceramics would be integrated in about 20 minutes in the absence of zirconium oxide. After that, Tc onset = 93 to make it easier for the thin film to grow crystals.
A superconducting thin film of k (resistance began to drop below 93k, and at experiment 83k the resistance became substantially zero) could be made. Needless to say, it does not have superconducting properties at all without this blocking thin film.

Then, this thin film was subjected to predetermined patterning by photolithography. Thus the electrodes and inputs of the device,
Photoresist coated to form electrodes and leads (5) for interconnection including connection to output terminals, and selectively removed (etched) with an acid solution diluted with water, for example, sulfuric acid or nitric acid.
Then, FIG. 1 (C) was obtained.

Plasma etching using bromine (Br ₂ ) gas may be performed for this selective etching. In such a case, anisotropic etching of an ECR (electron spin resonance) device was particularly effective.

It is effective to perform this patterning after forming the above-mentioned superconducting thin film, and then perform thermal annealing to selectively crystallize only the patterned interaction portion.

In this case, since the crystal grain size is small in the initial state, a finer pattern of interconnection can be obtained.

In FIG. 1 (D), after that, multilayer wiring was performed as needed.
For this reason, the interlayer insulator (6) was formed of an organic resin such as PIQ (polyimide resin), an opening was further formed, and then the leads (7) and (7 ') of the second layer were produced. And as the second layer, the lead (7) of oxide superconducting ceramics,
(7 ') was constructed.

Second Embodiment FIG. 2 shows another embodiment of the present invention.

The drawing is an enlarged view of only the C / MOS FET (complementary IGFET) part.

In the drawing, a silicon semiconductor substrate (1) that can withstand thermal annealing is used. Further, a P-type well (15) is provided to form a field insulating film of, for example, silicon oxide (11). One
An IGFET (insulated gate type field effect semiconductor device) (20) is provided with a gate electrode (12), a source or drain (13) and a drain or source (14) as impurity regions of P type conductivity type as a P channel IGFET. . Then, a blocking conductive film (21) is provided on the impurity region. The other IGFET (20 ') includes a gate electrode (12'), a source or drain (13 ') as an N-type impurity region,
It was provided as a drain or a source (14 ') to form an N-channel type IGFET. A blocking conductive film (21) is provided in this impurity region. Gate electrodes (12), (12 ')
Is polycrystalline silicon or metal silicide, and electrical interconnections and other interconnections (5) and (7) are formed in Example 1.
It was formed of the same superconducting material as.

In this embodiment, in the insulating film (2) on the lower surface of the superconducting ceramics (5), at least the insulating film (2-2) having a blocking property on the side close to the ceramics and the silicon oxide (for example (11)) below the insulating film (2-2). Alternatively, separately from this, an insulating film (2-1) containing silicon such as phosphorus glass or silicon nitride as a main component may be formed thereon. Further, another insulating material (6 ') which covers the upper surface of the superconducting material (5) is also provided with an insulating film also having a blocking action, for example, zirconium oxide by a sputtering method or an organic resin coating method.

If the superconducting material is made by a vapor phase method or the like and the active element provided on the lower substrate is not damaged at all, the gate electrode may also be made of the superconducting material.

In the examples of the present invention, zirconium oxide is mainly shown as the blocking material. However, other strontium titanate or YSZ may be used. Further, it is also effective to form a material having the same main component as that of the superconducting material and having non-superconductivity on top of them in order to prevent the respective materials from being mixed with each other. Further, a superconducting material may be formed as a lead or the like on the insulating film (6) as the second conductive film (7). In the present invention, when the oxide superconducting ceramics is burned for a long time, the superconducting material has a thickness of 1 μÅ or less, so that it does not combine with or mix with each other to deteriorate the superconducting property. It is important to have

[Example 3] This example is an enlarged view of an IGFET such as one IGFET (20) shown in Example 2.

In the drawing, a substrate (1) is made of silicon, and a field insulating film (11) of silicon oxide, a source or a drain (1
3), having an impurity region forming a drain or a source (14). It also has a gate (12). Further, on these semiconductors (1), (13) and (14) and on the field insulator (11), silicon oxide, silicon nitride or a multilayer film (41) of these is provided. Furthermore, an insulating film (40) having a blocking action of zirconium oxide or the like is further provided on this.
The impurity regions (13) and (14) have openings (42) in the insulating film (4).
A part of 1) is covered with a blocking insulating film (40 '). Further, the impurity region (1
3), (14) is provided with a metal that makes ohmic contact with it, such as tungsten, molybdenum, titanium, platinum or their silicides (15), on which multiple layers of platinum, gold,
Silver (16) is provided. The oxide superconducting materials (17), (1) are formed by the blocking conductor (21) and the blocking insulating film (40) which are made to have the same size as these openings.
The lower surfaces of 7 ') and the oxide non-superconducting material (27) are all covered so that the oxide does not come into direct contact with the oxide ceramics. (17) and (17 ') are electrodes and leads with superconducting properties. Here, the region close to the blocking conductor (21) is considered as an electrode. Further, (27) is an isolation region between leads in which oxide superconducting ceramics is added with 5 to 20% by volume of aluminum, magnesium or the like by an ion implantation method so as to have non-superconducting characteristics. Thus, with this filler, the oxide superconducting electrode
The leads (17) were enclosed on the outside and they could be approximately flush with each other.

Furthermore, the interlayer insulating film (28) and the multilayer connecting portion (18),
(18 ') are provided in the same manner. Here, most of it is formed as an interlayer insulating film (28 ').

In addition, electrodes and leads of oxide superconducting material for the second layer (1
9) and (19 ') and the filling insulating film (29) were made at the same time. For all of these, a blocking insulating film (30) was formed as final passivation. Here, the zirconium oxide and YSZ are sputtered to 0.1-
The thickness is 2 μm, for example 0.3 μm.

An electrode (33) for external extraction was made from a platinum contact (31) and a connecting metal (32) such as aluminum or gold. Also in final passivation, it is effective to cover the electrodes / leads of these oxide superconducting materials with an insulating film having a blocking action in order to have high reliability.
Especially, since this material also blocks water, deterioration of the superconducting ceramics could be prevented.

"Effects" The present invention makes it possible for the first time to put these semiconductor devices into practical use when they are formed by cooling at room temperature.

In particular, the frequency characteristics of a semiconductor can be improved by cooling it to the temperature of liquid nitrogen. On the other hand, the present invention uses a superconducting material without using a metal whose resistance increases at a low temperature. Moreover, the insulating material in contact with the lower surface of the superconducting material is a blocking material so that the superconducting material can be effectively used, and the material is also a blocking conductive material.

Therefore, by developing the technical idea of the present invention,
It has become possible to apply to ultra super LSI such as 16M to 1G bit.

In the present invention, the semiconductor may be a compound semiconductor such as GaAs instead of silicon. Ga on the silicon semiconductor
This semiconductor thin film may be used by subjecting a III-V compound semiconductor such as As to heteroepitaxial growth. By doing so, it becomes possible to point to ultra-high speed operation. However, it is necessary to reduce the annealing temperature so as not to deteriorate the semiconductor substrate during the annealing.

In the present invention, the superconducting material is a copper oxide superconducting material.
However, it is also effective to use another superconducting material capable of forming a fine pattern.

In the present invention, a semiconductor material provided with an active element and a non-oxide material provided on the upper surface thereof are used as the substrate. However, a ceramic material such as YSZ (yttrium stabilized zircon) or SrTiO _{3 having} a thermal expansion coefficient substantially the same as that formed on the upper surface of an alumina plate may be used as the substrate. Then, the thermal expansion coefficient can be matched, so it is easy to make. However, on the other hand, when such a material is used, an active element must be separately provided, and it has a drawback that it is difficult to achieve an ultra-high integrated circuit.

[Brief description of drawings]

 FIG. 1 shows the manufacturing process of the present invention. 2 and 3 show another embodiment of the present invention.

Claims (2)

[Claims] 1. An insulating film having silicon oxide, silicon nitride, or a main component thereof on an impurity region above a semiconductor substrate, a blocking insulating film provided on an upper surface of the insulating film, and an opening provided in the insulating film. A superconducting device in which a blocking conductive film is provided on the impurity region of the opening, and an oxide superconductor is provided on the blocking conductive film and the blocking insulating film, wherein the blocking insulating film Is zirconium oxide, or
A superconductor device comprising YSZ (yttrium-stabilized zircon), yttrium oxide, or a non-superconducting material having the same main component as an oxide superconducting material, or a multilayer film of these materials. 2. The blocking conductive film according to claim 1, wherein molybdenum, titanium, tungsten, platinum, or a silicide thereof is provided in close contact with an impurity region of a semiconductor, or platinum or silver is provided in multiple layers thereon. A superconductor device characterized by the above.