JPH011255A - How to wire integrated circuits - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application 1] The present invention relates to a wiring method for an integrated circuit using a superconducting composite oxide as a wiring material.

[Conventional technology 1] Wiring technology is extremely important as a basic technology that influences the performance and degree of integration of integrated circuits.

[) Ennard et al. discussed the miniaturization and performance of MOS transistors in a unified manner and called it the ``scaling law'' [IEEE J, 5solid-8tate Cir.
Cuits, 5C-9, 256 (1970)]. According to the scaling law, if, for example, the planar dimensions are reduced to 1/k, and the vertical structure is also reduced to 1/k, interconnect resistance and interconnect delay will double, causing deterioration of LSI characteristics and reliability. Therefore, it is considered difficult to reduce vertical structures such as the thickness of wiring and interlayer insulating films. 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 A1-3i are most often used as wiring materials (MOS LSI Manufacturing Technology, Nikkei McGraw-Hill, 1985). but,
Essentially, when these metals are used, heat is generated due to resistance, so 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 Invention] The present invention has been made in consideration of the above points, and by making the wiring resistance substantially zero, it is possible to reduce the aspect ratio regardless of the scaling law. Therefore, it is an object of the present invention to provide a method for manufacturing an element that can be easily processed for wiring, can be highly integrated, and can operate at a relatively high speed.

[Means for Solving the Problems] As a result of extensive 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, They discovered that high integration and high speed operation were possible, and completed the present invention.

That is, the method for manufacturing an integrated circuit of the present invention includes a step of forming a thin film of a superconducting composite oxide on a substrate, forming a photosensitive resin oil III on the composite oxide, and applying energy beams to form a predetermined pattern. , a step of removing unnecessary portions of the superconducting composite oxide by etching, and a step of removing the photosensitive resin thin film, and the aspect ratio of the wiring of the superconducting composite oxide is 2 or less. There is a need for an integrated circuit wiring method characterized by the following features.

Hereinafter, the integrated circuit wiring method of the present invention will be explained in detail.

The present invention is characterized in that a superconducting composite oxide is used as the wiring material, and as a result, the wiring resistance becomes U, so the integrated circuit that does not generate heat in the wiring part and is capable of high-speed operation can be manufactured. You will be able to create.

As superconducting composite oxides, 1i-Ti-〇 series, Rb
-W-○ system, (Pb-Bi)-Tio system, or (RE-M)-Cu-0 system (M is at least one selected from Ba, Sr, and Ca). Among them (RE
-M)-Cu-0-based composite oxides have a superconducting critical temperature equal to or higher than the temperature of liquid nitrogen, so they are preferred in practice. Here, RE is 3c, Y, La1Ce, Pr,
Nd, Sm.

Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and l
-Represents a rare earth element such as u, and one or two of these
More than one species can be used. (RE-M)-Cu-0
In the system, the composition ratio of RE and M varies depending on the type of RE, but it is preferable to set the content of M in an atomic ratio of 20% to 90% 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 3i, Ge, Ga-A
There is a thin plate of f nanoeye 7 having a single crystal thin structure of S, Ga-P, In-3b, or 3i, and refers to a material provided with an insulating layer such as an oxide or nitride as necessary. Further, since a wiring pattern is 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. Furthermore, in the case of multilayer wiring, a substrate on which elements and wiring patterns are formed is also included.

In J3 of the present invention, there are sputtering methods, molecular beam epitaxial methods, and actinic beam epitaxial methods as methods for forming a thin film of superconducting composite oxide on a substrate, and the manufacturing method is selected depending on the properties of the required thin film. I can do something.

As a method for forming a wiring pattern on the superconducting composite oxide, conventionally known methods can be applied. There are methods that use visible light, ultraviolet rays, far ultraviolet rays, electron beams, and X-rays as energy rays, and that are exposed through a photomask and then developed to form a predetermined pattern, or using electron beams, laser beams, or ion beams. You need a way to draw directly.

For positive type photosensitive resins, quinone azide resins based on phenol and cresol novolak resins are used for visible light and ultraviolet light sources, polymethyl methacrylate and polymethyl isopropenyl ketone for deep ultraviolet light sources, X-ray and electron Polymethyl methacrylate resin is used as a radiation source.

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

In the integrated circuit manufacturing method of the present invention, the aspect ratio (ratio of thickness to width) of the wiring can be made 2 or less, and it is generally preferable to make it 0.5 or less, but this is due to the electrical resistance of the wiring. or substantially zero.

If the aspect ratio is as large as 2 or more, it is not preferable because there are disadvantages in that etch residues may be left during etching when wiring is formed, and that it is difficult to embed the insulating film when forming an interlayer insulating film.

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 on the semiconductor substrate 1 on which elements are formed by a predetermined method, and a thin film 3 of superconducting composite oxide is formed on the base plate on which this insulating film 2 is provided by the method described above. Form.

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 with a predetermined wiring pattern drawn thereon.Contact exposure and proximity exposure are used for ultraviolet-visible light and deep ultraviolet resists. Although it is common, projection exposure or 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 novolac resin and a diazide compound are used as the photosensitive resin, it is preferable to use an aqueous alkali solution, particularly an organic alkaline developer using an aqueous quaternary ammonium salt solution.

Next, a boss bake is performed to improve the adhesion between the substrate and the resist during etching, and is usually baked at the upper limit temperature that does not cause deterioration of the polymer. For example, in the case of a phenol novolac resin, it is preferable to carry out the heating at 80 to 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. As for the etching method,
There are wet etching methods and dry etching methods. The wet etching method is carried out by dissolving and removing the parts not covered by the photosensitive resin thin film, and the etching liquid used is nitric acid, hydrofluoric acid, hydrofluoric acid + nitric acid, nitric acid + phosphoric acid,
Alternatively, butyric acid, decanitrate, glacial acetic acid, and glacial acetic acid can be used.

Dry etching is characterized by higher processing accuracy than wet etching, and can be carried out by sputter etching or ion milling using Ar, or by plasma etching using activated scum.

The photosensitive resin thin film remaining on the superconducting i raw composite oxide thin film after etching is firmly attached by post-baking, so it is immersed in a peeling agent mainly composed of heated phenol or halogen-based organic solvent. It is necessary to peel it off. In addition, a plasma ashing method can also be applied, or is preferably used in combination with a dipping method in that it can be completely removed.

Through the above steps, a wiring pattern of superconducting composite oxide 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 keep the aspect ratio small without relying on scaling laws, so conventional lithography technology can be applied, and multilayer wiring can be easily done. It has the advantage of being able to do

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

[Example 1 Hereinafter, the present invention 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, 3 is a superconducting composite oxide thin film, 4 is a positive resist film, and 5 is a photomask.

First, as shown in FIG. 1, 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. YBa2Cu3068 was used as the target, and Mf
fi partial pressure 2X10-2Torr, substrate temperature 300'C
After sputtering under the following conditions, a thin film with a thickness of 0.5 μm was obtained by annealing at 850° C. for 2 hours in oxygen for 7 hours.

Next, as shown in FIG. 2, a 1 μm thick phenol novolak resin 10-quinone diamide was applied as a photosensitive resin thin film on the superconducting composite oxide thin film 3 at 600 or
m for 20 seconds using a spinner method, followed by 85 m
Prebaked for 20 minutes at a temperature of °C.

As shown in FIG. 3, using a photomask 5 on which a predetermined wiring pattern is drawn, ultraviolet rays (380 nm) are used to
The film was exposed to light for 2 seconds, developed with a tetramethylammonium hydroxide solution for 60 seconds as shown in FIG. 4, and washed with water.

Post-bake was performed at 110'C for 30 minutes, and the etching shown in Figure 5 was phosphorus! The test was carried out using a mixed aqueous solution of (20% by volume) + nitric acid (5% by volume). Next, as shown in FIG. 6, the remaining resist film was removed using O-dichlorobenbin to form a predetermined wiring pattern of superconducting composite oxide.

The width of the superconducting composite oxide thin film 1 was 2.3 μm (aspect ratio 0.22), and a predetermined wiring pattern could be formed. Furthermore, when the resistance of the material obtained here was measured at a temperature of 77°C, it showed superconductivity.

Example 2 Using ErBa2Cu10G and il as a target,
Oxygen partial pressure 'l x 10-' Torr, substrate temperature 25
A thin film with a thickness of 0.3 μm was obtained by performing magnetron sputtering at 0'C and then annealing in an enzyme at 850'C for 2 hours.

Next, a wiring pattern of superconducting composite oxide was formed in the same manner as in Example 1 except that etching was performed by ion milling using Ar gas.

The width of the superconducting composite oxide thin film 1 was 1.6 μm (aspect ratio 0.19), and a predetermined wiring pattern could be formed. Furthermore, when the resistance of the material raised by 1 was measured at a temperature of 77, 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 1 was 1.0 am (aspect ratio 0.5), and when its resistance was measured at a temperature of 77°C, it showed superconductivity.

[Effects] As explained above, according to the present invention, wiring processing is easy, high integration is possible, and the device can be operated at a relatively high speed, so it is extremely useful in the industrial field. be.

[Brief explanation of drawings]

1 to 6 are explanatory diagrams showing each step in an embodiment of the method of the present invention. 1... Silicon substrate, 2... Silicon oxide film, 3.
... Thin film of superconducting composite oxide, 4... Thin film of photoresist, 5... Necessary for photomask. Patent applicant: Asahi Kasei Industries, Ltd.

Claims (1)

[Claims] A step of forming a thin film of 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, An integration comprising a step of etching and removing unnecessary parts of a conductive composite oxide thin film and a step of removing a photosensitive resin thin film, and characterized in that the aspect ratio of the wiring of the superconducting composite oxide is 2 or less. How to wire a circuit.