JPH0736404B2 - Method for manufacturing superconductor device - Google Patents

Description

The present invention relates to a method for producing a superconducting device using an oxide ceramic superconducting material. The present invention particularly relates to a superconductor device in which a part or all of interconnections of a semiconductor device is formed by a lead in which an oxide superconducting material and a metal or a metal semiconductor compound are superposed on each other, and the lead has a metal or metal semiconductor compound. The upper surface of the conductor and the electrode of the semiconductor device are constituted by a connecting portion of a metal or a metal semiconductor compound, and the semiconductor device is operated at a temperature of 70 to 300K, preferably 77K or higher.

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

Recently, it has been known that a ceramic material 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.

On the other hand, a semiconductor device in which a plurality of elements including a semiconductor integrated circuit are provided on the same substrate is known. However, no attempt has been made to operate this semiconductor device at a low temperature such as liquid nitrogen temperature (77K).

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

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 addition, in order to solve such a problem, the present application (Showa
Applied on March 9, 62 Superconducting semiconductor device Japanese Patent Application No. 62-05372
4) is not used. In such a superconductor semiconductor device, the lead wire is made of a superconducting material such as a ceramic material. After forming the material on the surface to be formed, such a material must be oxidized in an oxide atmosphere for a long time. Therefore, in the electrode portion of the semiconductor element, the oxide of the semiconductor forming the element is formed in the electrode portion. It has been found that this oxide is generally an insulator, and a silicon oxide insulating film is formed on the electrode portion of a semiconductor such as a semiconductor integrated circuit.

[Means for Solving the Problem] In order to solve such a problem, the present invention uses a material exhibiting superconductivity at a low temperature (temperature of 70 to 300K) for interconnection in a semiconductor device. At that time, a metal or metal semiconductor compound is provided by superimposing it on the superconducting material, and the metal or metal semiconductor is brought into close contact with the electrode portion of the semiconductor element, and a metal or alloy semiconductor compound which does not form an oxide with the semiconductor is formed. It is configured by.

The present invention is a semiconductor, particularly preferably a semiconductor having heat resistance,
For example, a single crystal silicon semiconductor substrate is used, and a plurality of elements such as an insulating gate type field effect transistor, a bipolar type transistor, a SIT (static induction type transistor), a resistor and a capacitor are provided on this semiconductor. Then, a heat-resistant insulating material, particularly preferably heat-resistant silicon nitride or silicon oxide is provided on this and the insulating film on the upper surface thereof. Then, a thin film material of an oxide superconducting material having an electric resistance of zero or close to zero is formed on the insulating film. On top of this, copper, silver,
A thin film of a metal semiconductor such as gold, aluminum, WSi ₂ , MoSi ₂ is formed. Next, the metal or the semiconductor compound of the metal and the superconducting material are both selectively etched by the photolithography technique and patterned.

According to the present invention, a superconducting material and a conductor of a metal or a metal-semiconductor compound are provided on an upper surface of an insulating substrate, and a flip chip is mounted on the conductor of such a lead by a wire bonding method using bumps or connecting portions of a semiconductor integrated circuit. A device, a resistor, etc. may be provided.

"Operation" When the temperature of such a semiconductor device is set to 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. R (resistance) in the CR time constant indicating the delay of the frequency characteristic can be set to zero,
Therefore, extremely high speed operation can be performed.

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

Example 1 FIG. 1 shows an example of an insulating gate type field effect semiconductor device.

In FIG. 1 (A), a silicon semiconductor substrate (1) was constructed. Further, a field insulating film (2) having an insulating surface is formed by a selective oxidation method except for a region which constitutes an active element. Furthermore, about 200 gate insulating film (3)
Å Thickness is formed by high temperature oxidation method. Next, a very thin silicon nitride film was formed on the surface. The blocking film (4) is a solid-gas phase reaction in which a silicon oxide film is reacted with ammonia or the like, and has a thickness of 5 to 20 Å.

Next, the entire substrate was heated to 700 ° C. by a sputtering method to form an oxide superconducting material. In this case, YBa ₂ Cu _3.6 O ₆ to ₈ was used as the target. The thin film (5) formed was made of YBa ₂ Cu ₃ O ₆ to ₈ exhibiting superconducting properties without thermal annealing, and Tco was set to 84K.

The thickness of the oxide superconducting material (5) was 0.1 to 2 μm, for example 0.5 μm.

Next, a metal film (6) was formed on this upper surface by a sputtering method using the same apparatus. Here 100-100 with copper, silver or gold
A conductor of 00Å was formed. On top of that, TiSi ₂ is 0.1-0.
The thickness may be 5 μm, for example, 0.3 μm. Silicon, which has the same main component material as the substrate to which phosphorus or boron is added instead of Si as a part of the semiconductor substrate (1), or a non-oxidizing heat-resistant metal such as tungsten, It may be a metal semiconductor compound such as WSi ₂ . In this example, a heat resistant material was used because heat resistance is required.

Thus, the multilayer film (7) in FIG. 1 (A) was formed.

Further, a photoresist (8) was selectively provided on this, and the conductor (6) and the oxide superconducting material (5) in the portion without the photoresist were removed by an etching method. The oxide superconducting material can be etched with an acid such as sulfuric acid or hydrochloric acid.

The selective removal of the conductor (6) was performed by using known plasma etching.

After this, the photoresist (8) was removed.

In FIG. 1 (B) thus obtained, a lead (10) on the field insulating film (2) (a lead for connecting with a semiconductor electrode), a lead (10 ') using an oxide superconducting material, The gate (11) is also provided with a gate electrode (9) using an oxide superconducting material. After that, the source (12) and drain (13) were constructed by ion implantation and thermal annealing. This thermal anneal is performed at 950 ° C. to improve the properties of the superconducting material. After that, it was gradually cooled, and additional annealing was performed at 500 to 600 ° C. for 1 to 2 hours. By this additional annealing, the oxide superconducting material becomes a deformed perovskite structure having an orthorhombic structure rather than a tetragonal structure, and the superconducting property is improved.

After that, an interlayer insulating film (10) (for example, silicon oxide) is formed in a thickness of 0.3 to 1 μm on the whole by a vapor phase method, and the hole portions (15), (16) are further formed by a known foot etching method.
I made it. Part of the opening (15) exposes the conductor above the multilayer lead (10), and the other part constitutes the electrode part (15-2) of the semiconductor element.
Next, make the second layer lead (18) and at the same time lead (10)
Forming a connecting portion (19) between the upper surface (15-1) of the electrode and the electrode (15-2).

This was formed by forming aluminum to a thickness of 0.3 to 1 .mu.m and performing photoetching on it as shown in FIG.

Thus, the electrical connection (19) between the lead (10) having zero resistance and the electrode portion (15-2) of the semiconductor element is such that the oxide superconductor material indirectly connects through the conductor (19), It was possible to connect the oxides of the material to each other while preventing the formation of the insulating film that is easily formed on the electrode portion.

In FIG. 1 (D), (18) is only a metal lead, so it is possible to select a material and make it act as a resistance material.

The wiring of the second layer of (18) is a metal film of aluminum.
It is provided to a thickness of 1 to 0.3 μm, and a non-reactive metal is deposited on it.
If the lead is formed by forming the oxide superconducting material on it with a thickness of 05 to 0.2 μm and then photoetching this, the second layer can also be a lead with zero resistance. Is.

That is, in the wiring of the first layer, the lead has an oxide superconducting material and a conductor (metal, semiconductor, or metal-semiconductor compound) formed thereon, and in the wiring of the second layer, the ohmic contact is made with the semiconductor, and A conductor that does not react is provided, and an oxide superconducting material is provided on the conductor so that the resistance is zero and the metal conductors are brought into close contact with each other at the connecting portion.

In the present invention, copper, silver or gold was used in close contact with the superconducting ceramics. However, since the metal becomes an interstitial atom for the semiconductor, it is possible to make a good ohmic contact with aluminum, WSi ₂ , MoSi ₂ , and Si that are brought into close contact with the semiconductor.

Thus, as shown in FIG. 1D, it is possible to provide a plurality of field effect semiconductor devices on the same substrate and obtain a VLSI.

In FIG. 1 (A), the oxide superconducting material was formed by the sputtering method. However, a screen printing method, a vacuum vapor deposition method or a vapor phase method (CVD method) may be used. As an example of the sputtering, the substrate temperature was 700 ° C., the atmosphere was argon / oxygen, the frequency was 50 Hz, and the output was 100 W. In such a case, the thickness of the ceramic material is set to 0.2 to 2 μm, for example, 1 μm, and Tc onset = 95K (the resistance starts to drop below 95K, in order to facilitate the growth of a crystal in which the thin film exhibits superconductivity simultaneously with the formation of the film. Experimentally, a superconducting thin film with a resistance of substantially zero at 79K could be made.

The oxide superconducting material of the present invention is (A _1-x Bx) yCuzOw (A is one or more elements selected from Group IIIa of the periodic table of elements, B
Is one or more elements selected from Group IIa of the Periodic Table of Elements, and x = 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) is used.

Example 2 FIG. 2 (A) is a modification of the example of FIG. 1 (D). In FIG. 2 (A), a lead (10) having an oxide superconducting material is provided with a first metal lead (6-2) on the lower side thereof, and a lead (5) of an oxide superconducting material is provided thereon. Conductor that does not form an insulator by reacting with the oxide superconducting material (6
-1) and a lead (10) having a three-layer structure. Further, the electrode portion (15-1) of the lead (10) and the semiconductor electrode (15-2) were connected to each other by a conductor forming a conductor connecting portion (19).

It is important that the connecting portions (19) make ohmic contact with each other with sufficiently low resistance. For example, the selective growth method of tungsten is used. Then, other connecting parts (1
Also has 9 '). Therefore, the lower surface of the lead (18) can have a multilayer structure including the oxide superconducting material (21) and the metal conductor (22) in close contact therewith.

“Reference Example” A reference example is shown in FIG. The substrate in FIG. 2 (B) is a heat-resistant insulating substrate (1), for example, an alumina substrate having a matched thermal expansion coefficient, YSZ (yttrium stabilized zircon), or strontium titanate.
An oxide superconducting material was provided thereon in the same manner as in Example 1. Further, a conductor was provided thereon by using copper and silver, and a chip (20) such as a semiconductor device was connected to these printed wiring boards by a bump (21) (connecting portion) in a face-down method.

Such a structure has a feature of facilitating heat treatment conditions such as no active element sensitive to heat treatment in the substrate. However, it has a drawback that it is difficult to perform precise patterning.

"Effects" The present invention makes it possible for the first time to put the semiconductor device into practical use when it is formed by cooling the semiconductor device 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.

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

[Brief description of drawings]

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

Continuation of the front page (56) Reference JP-A-64-27244 (JP, A) JP-A-63-318755 (JP, A) JP-A-60-154613 (JP, A) Physical Review Letters, vol58, No9 ． PP. 908-910 (2 Mar 1987) Japanese Journal of Applied physics, vol. 26, No. 6 (June 1987), PP. L1017 ~ L1018

Claims (1)

[Claims] 1. A step of providing a thin film of an oxide superconducting material on a field insulator on a substrate, and a thin film of copper, silver or gold on the thin film, and selectively removing the multilayer thin film from other parts. And the copper or silver or gold on the upper part of the lead and the electrode part of the semiconductor on the substrate are aluminum or WSi ₂ or MoSi.
_{2. A} method for producing a superconductor device, comprising the step of connecting with ₂ or Si.