JPS63249353A - Wiring method for integrated circuit - Google Patents

Abstract

PURPOSE:To enable a high integration and a high-speed operation by effectively zeroing the electrical resistance of the wiring part, thereby making the aspect ratio small without depending the scaling rule. CONSTITUTION:On a substrate 1 a thin film 3 of a superconducting composite oxide 3 is formed, on this composite oxide 3 a photosensitive resin thin film 4 is formed, and a predetermined pattern in formed using a energy beam. And with the photosensitive resin thin film 4 as a mask the unnecessary part of the superconducting composite oxide 3 is removed, and the photosensitive resin thin firm 4 is removed. By effectively zeroing the wiring resistance using as a wiring material the superconducting composite oxide 3 having a high critical superconduction temperature, it is made possible to make the aspect ratio small independently of the scaling rule. With this, the wiring process becomes easy, a high integration is provided, and a high-speed operation is enabled.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Field of Application) The present invention relates to a method of wiring an integrated circuit using a superconducting composite oxide as a wiring material.

(Prior Art) Wiring technology is extremely important as a basic technology that influences the performance and degree of integration of integrated circuits.

Dennard et al. discuss the v & thinning and performance of MOS) run sisters in a unified manner,
Il” > gl, f:: /II; Tr
I-(^1ir4j;+, negative+, 5-Circuits
, Ezoe, 256 (1970)) @ According to the scaling law 9 For example, when reducing the plane dimension to 1/k.

If the vertical structure is also reduced to 1/k, the wiring resistance and wiring delay will increase twice, causing deterioration of LSI characteristics and reliability, so it is difficult to reduce the vertical structure, such as the thickness of the wiring and glabellar insulating film. It is said that there is. Therefore, when increasing the degree of integration, the aspect ratio of wiring tends to increase. The increase in aspect ratio poses a major obstacle to interconnection formation technology, ie, lithography and microfabrication techniques for processing interconnections.

At present, A1 and At-5i are used as wiring materials in most cases (MOS LSI
Manufacturing Manufacturing Technology 0 Ma McGraw-Hill 1985). However, since the use of these metals essentially generates heat due to resistance, it becomes difficult to further increase the degree of integration by multilayering or miniaturizing elements. Further, due to the wiring resistance, the mobility of electrons decreases, resulting in a disadvantage that the operating speed of the device decreases.

(Problems to be Solved by the Present Invention) The present invention has been made in consideration of the above points.

By making the wiring resistance virtually zero, it is possible to reduce the aspect ratio regardless of the scaling law, which allows for easy wiring processing, high integration, and a manufacturing method for devices that can operate at high speed. It is something to do.

(Means for Solving the Problems) As a result of intensive research in order to solve the above problems, the present inventors have found that by using a superconducting composite oxide having a high superconducting critical temperature as a wiring material, .

We have discovered that high integration and high speed operation are possible, and have completed the present invention. , That is, one method of manufacturing an integrated circuit according to the present invention includes a step of forming a thin film of a superconducting composite oxide on a substrate.

A step of forming a photosensitive resin thin film on the composite oxide and forming a predetermined pattern using energy rays.

This method of manufacturing an integrated circuit is characterized by comprising a step of removing unnecessary portions of the superconducting composite oxide using a photosensitive resin thin film as a mask, and a step of removing the photosensitive resin thin film.

Hereinafter, nine integrated circuit wiring methods of the present invention will be described in detail. One feature of the present invention is that a superconducting composite oxide is used as the wiring material, so that the wiring resistance is zero, so there is no heat generation in the wiring portion.

Moreover, it becomes possible to manufacture integrated circuits capable of high-speed operation.゛ As a superconducting composite oxide, Li-
Ti-0 series, Rb-W-0 series, (Pb・B i) -T
There are i-0 series and (RE-M)-Cu-0 series (M is at least one selected from Ba, Sr, and Ca). Among these, (RE.M)-Cu-0-based composite oxides are practically preferred because their superconducting critical temperature is equal to or higher than the temperature of liquid nitrogen. Here, as RE, 5C
9Y.

La, Ce, Pr, Nd, Sm, Eu, ca.

It represents rare earth elements such as Tb, Dy, Ho, Er, Tm, Yb, and Lu, and one or more of these can be used. In the (RE-M)-Cu-0 system, the composition ratio of RE and M varies depending on the type of RE, but 9M
It is preferable to set the content of 20% to 70% in terms of atomic ratio because the superconducting critical temperature can be increased.
By controlling the oxygen content of the composite oxide, it is possible to raise the superconducting critical temperature, and by changing the atmosphere when forming the thin film of the superconducting composite oxide, or by changing the atmosphere in a predetermined atmosphere after forming the thin film. This can be done by annealing.

The substrate referred to in the present invention is Si, Ge, or Ga-As.

There is a thin plate of sapphire having a Ga-P, In-9b, or Si single crystal thin film layer, and refers to a material provided with an insulating layer such as an oxide or nitride as necessary. Furthermore, since wiring patterns are usually formed after various elements are formed on a substrate, the substrate of the present invention includes the above-mentioned substrate on which elements are formed. moreover.

In the case of multilayer wiring, a substrate on which elements and wiring patterns are formed is also included.

In the present invention, methods for forming a superconducting composite oxide thin film on a substrate include sputtering, 9-molecular beam epitaxial method, and actinic beam epitaxial method, and the manufacturing method is selected depending on the required properties of the thin film. be able to.

Conventionally known methods can be used to form a wiring pattern on the superconducting composite oxide. Visible light, ultraviolet rays, deep ultraviolet rays, electron beams, and X-rays are used as energy rays to form a predetermined pattern after exposure through a photomask and development.

There are two methods: direct writing using an electron beam, laser beam, or ion beam.

For positive type photosensitive resins, quinone azide based resins based on phenol and cresol novolac resins are used for visible light and ultraviolet light sources.

Deep ultraviolet light sources include polymethyl methacrylate and polymethyl isopropenyl ketone, and X-ray and electron beam sources include polymethyl methacrylate.

On the other hand, if you want to use a negative type, cyclized isoprene rubber or polycinnamic acid type can be used as a visible light or ultraviolet light source, chlorinated polystyrene can be used as a deep ultraviolet light source, and epoxy polymer can be used as an X-ray or electron beam source. , you can use it as needed. The photoresist material used with the light source or radiation source can be selected in consideration of the required resolution, sensitivity, etching resistance, etc.

Next, one embodiment of the present invention will be described in detail.
The steps shown in the drawings will be described below, but the present invention is not particularly limited thereto. here,
An example using a positive resist material will be explained.

An insulating film 2 such as an oxide film is formed by a predetermined method on a semiconductor substrate 1 on which elements are formed, and a thin film 3 of a superconducting composite oxide is formed by the method described above on the substrate provided with this insulating film 2. do. Next, a photosensitive resin thin film 4 is formed on the superconducting composite oxide thin film 3, and the solvent is removed from the film by baking. Methods for forming a photosensitive resin thin film include a spinner method, a spray method, a roll method, a coater method, and a dipping method, and a spinner method is preferred as a method for forming a uniform film.

Next, the photosensitive resin thin film is exposed to light using a predetermined light source or line source through a photomask 5 on which a predetermined wiring pattern is drawn. For ultraviolet-visible light and deep ultraviolet resists, contact exposure and proximity exposure are generally used, but projection exposure and reduction exposure can also be performed.

For development and rinsing, a spray method or a dipping method can be applied, but it is necessary to use a developing solution and a rinsing solution suitable for the resist. For example, when a phenol novolak resin and a diazide compound are used as the photosensitive resin, it is preferable to use an aqueous alkaline solution, particularly an organic alkaline developer using an aqueous quaternary ammonium salt solution.

Next, a boost bake is performed in order to improve the adhesion between the substrate and the resist during etching (2) and is usually baked at the upper limit temperature that does not cause deterioration of the polymer.

For example, phenol novolac resin type has 80~
Preferably, the temperature is 160°C.

Next, in order to form a circuit pattern on the superconducting composite oxide thin film 1, etching is performed to remove unnecessary portions of the superconducting composite oxide thin film using the pattern of the photosensitive resin thin film as a mask.

Etching methods include wet etching and dry etching. The wet etching method is
This is done by dissolving and removing the parts not covered by the photosensitive resin thin film, and the etching solution is hydrofluoric acid, hydrofluoric acid + nitric acid, or nitric acid + phosphoric acid.

Alternatively, butic acid + nitric acid + glacial acetic acid, etc. can be used.

The dry etching method is characterized by higher processing accuracy than the wet method, and is performed by sputter etching or ion milling using vAr.

Alternatively, the etching can be carried out by a plasma etching method using an active gas.

The photosensitive resin thin film that remains on the superconducting composite oxide thin film after etching is firmly attached to the superconducting composite oxide thin film by post-baking, so it can be removed using a stripping agent mainly composed of heated phenol or halogen-based organic solvents, or hot concentrated sulfuric acid. It is necessary to remove the film by immersing it in a strong acid such as fuming nitric acid, sulfuric acid, or hydrogen peroxide. Also.

Although a plasma ashing method can also be applied, it is preferable to use it in combination with a immersion method because it can completely remove it.

Through the above steps, a superconducting composite oxide wiring pattern can be formed on the substrate.

According to the method of the present invention, since the electrical resistance of the wiring part is virtually zero, it is possible to easily reduce the aspect ratio without relying on scaling laws, so conventional lithography technology can be applied, and multilayer wiring can also be achieved. It has the characteristic of being easy to perform.

The multilayer wiring is obtained by forming a second insulating film on the superconducting composite oxide wiring pattern formed by the method of the present invention9 and then forming a superconducting composite oxide wiring pattern again by the method of the present invention. It can be carried out.

(Effects) According to the present invention, wiring processing is easy, high integration is possible, and an element capable of high-speed operation can be obtained, so that it is extremely useful industrially.

(Example) Hereinafter, it will be explained in more detail with reference to Examples.

Example 1 Embodiments of the invention will be described with reference to the drawings.

The drawings are cross-sectional views of a substrate according to steps, showing one embodiment of the present invention. In the figure, 1 is a silicon substrate, 2 is a silicon oxide film, and 3 is a superconducting composite oxide thin film.

4 is a positive resist film and 5 is a photomask.

First, as shown in FIG. 9, a superconducting composite oxide thin film 3 was formed by magnetron sputtering on a silicon substrate 1 on which a silicon oxide film 2 was formed. As a target.

(Y Ba ) Using CIJO3, oxygen partial pressure is 0
．． Sputtering was performed under the conditions of 50.5 2xlO-2 Torr and a substrate temperature of 800°C to obtain a thin film with a thickness of 0.6 μm.

Next, on the thin film 3 of the superconducting composite oxide, a phenol novolac resin 1 with a thickness of 1 μm is formed as a photosensitive resin thin film.
eoo 0-quinonediazide.

Formed using a spinner method at rpm for 20 seconds.

Subsequently, it was prebaked at a temperature of 86° C. for 20 minutes.

Using a photomask 5 with a predetermined wiring pattern drawn,
Exposure to UV light (380 nm) for 60 seconds, develop with tetramethylammonium hydroxide solution for 60 seconds,
Washed with water.

Post-baking was performed at 110° C. for 30 minutes, and etching was performed using a mixed aqueous solution of phosphoric acid (20% by volume) and deca-nitric acid (5% by volume). Next, the remaining resist film was removed using 0-dichlorobenzene to form a predetermined wiring pattern of superconducting composite oxide.

The width of the superconducting composite oxide thin film 1 is 2.3 μm,
A predetermined wiring pattern could be formed. Also,
When the resistance of the material obtained here was measured at a temperature of 77°C, it showed superconductivity.

Example 2 (Ce Si r ) Cu as target
Using O30,80,2, oxygen partial pressure 1xlO'Torr, substrate temperature 850
A wiring pattern of superconducting composite oxide was formed by the same method as in Example 1 except that magnetron sputtering was performed under conditions of 0.degree. C., followed by etching by ion milling using Ar gas.

The width of the superconducting composite oxide thin film 10 is 1.6 μm,
A predetermined wiring pattern could be formed. Also,
When the resistance of the material obtained here was measured at a temperature of 77°C, it showed superconductivity.

Example 3 A predetermined wiring pattern was formed in the same manner as in Example 1 except that polymethyl methacrylate was used as the photosensitive resin and direct drawing was performed using an electron beam.

The width of the superconducting composite oxide thin film 10 was 1.0 μm, and when its resistance was measured at a temperature of 77°C, it showed superconductivity.

[Brief explanation of drawings]

, the drawings are steps illustrating one embodiment of the invention. In the figure, 1 - silicon substrate, 2 m - silicon oxide film, 3 - superconducting composite oxide thin film. 4・−・・・−・・・・Photoresist thin film, 5−=−
-It is a photomask. Patent applicant Asahi Kasei Kogyo Co., Ltd. Drawing engraving No. 1 (d) Current East No. 1 (e) Etching (+) Resist stitching procedure amendment (method) % formula % 1. Indication of case 1985 patent application No. 083064 2, Name of the invention, Me-4, 1-2-6 Dojimahama, Kita-ku, Osaka-shi, Osaka Prefecture, Date of amendment order: June 3, 1988 Date of dispatch
June 30, 1988 5, "Detailed Description of the Invention" and "Brief Description of Drawings" column 6 of the specification subject to amendment, content of amendment 11) is this invention”
is corrected to read "Figures 1(a) to (f) are of this invention." (2) In the second line of page 14, "The drawings show the present invention" is corrected to "Figures 1 (a) to (f) show the present invention." (3) “Drawing” should be corrected as “Figure 1” as attached. that's all

Claims (1)

[Claims] A step of forming a thin film of a superconducting composite oxide on a substrate, a step of forming a photosensitive resin thin film on the composite oxide and forming a predetermined pattern using energy rays, and a step of using the photosensitive resin thin film as a mask. A method for manufacturing an integrated circuit, comprising the steps of etching and removing unnecessary portions of the superconducting composite oxide thin film, and then removing the photosensitive resin thin film.