JP2002234000A - Method for forming pattern of carbon nano-tube - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method capable of easily performing minute pattern forming of carbon nano-tube film and of forming a carbon nano-tube pattern of a good flatness, a good shape of a pattern end part, and improved reliability in isolation between elements. SOLUTION: When a pattern is formed with wet etching carbon nano-tube 6 by a transferring method, solution used for dissolving binder used in the transferring method is used as solution used for wet etching and carbon nano- tube entangled during wet etching is scoured off with cloth-like matter 12. When the pattern is formed by dry etching for the carbon nano-tube, metal film or film of material not damaged during dry etching and not damaging the carbon nano-tube during removal is used as a mask.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for forming a pattern on a carbon microstructured material containing carbon nanotubes.

[0002]

2. Description of the Related Art Carbon nanotubes are known to be chemically and mechanically tough, and are attracting attention as materials for electron sources. Carbon nanotubes are formed by nesting one or more cylinders of graphite-like carbon atoms with a thickness of several atomic layers rolled into a tube. The outer diameter is on the order of nm and the length is on the order of μm. It is a small tubular substance. A single cylinder is called a single-walled nanotube, and a plurality of nested cylinders is called a multi-walled nanotube.

[0003] As a method for producing carbon nanotubes, an arc discharge method, a CVD method, a laser ablation method and the like are known. The generated carbon nanotube is a soot-like mixture mixed with impurities such as carbon fine particles other than the carbon nanotube. In particular, in single-wall nanotubes and multi-wall nanotubes formed by the arc discharge method, catalytic metals such as iron, nickel, cobalt, yttrium,
Since it requires lanthanum and the like, it is a soot containing fine metal particles. Here, impurities such as carbon fine particles and metal fine particles such as a catalyst metal generated in the process of generation are referred to as nanoparticles.

In the process of purifying carbon nanotubes by the arc discharge method, at the time of discharge, first, the surface of the catalyst metal fine particles is coated with amorphous carbon, and a plurality of nanotubes grow from the coated amorphous carbon and are entangled with other nanotubes. The surface of the formed catalyst metal is covered with an amorphous carbon thin film. Further, carbon fine particles are also formed during the discharge and adhere to the nanotubes. In some cases, a plurality of carbon fine particles are bonded via the carbon fine particles. Thus, the carbon nanotubes are entangled by the fine particles.

[0005] These nanoparticles can be relatively easily removed from the carbon nanotubes produced by the arc discharge method. The carbon fine particles can be substantially removed in a short time in an oxygen atmosphere, for example, at about 450 ° C. in the air for about 15 minutes without causing deterioration of the nanotubes. In this method, carbon fine particles having many incomplete bonds between carbon atoms easily react with oxygen, and carbon fine particles are selectively oxidized and removed.

Further, in this step, the amorphous carbon covering the surface of the catalyst metal is removed, and the catalyst metal is exposed on the surface. This catalytic metal, for example, cobalt, yttrium, iron, nickel, and lanthanum can be removed by treating the above-mentioned heat treatment with, for example, about 35% hydrochloric acid for 2 hours or more. Since the amorphous carbon thin film covering the surface is removed by the heat treatment, it can be etched by an acid treatment.
The carbon nanotube from which the nanoparticles are removed is called a purified carbon nanotube.

In order to use carbon nanotubes as an electron source, it is necessary to form the above soot-like carbon nanotubes on a substrate as a carbon nanotube film. In particular, field emission displays (FE
In order to use it as an electron source of D), it is necessary to form a fine pattern of a carbon nanotube film.

In an FED using carbon nanotubes, a gate electrode for extracting electrons is located above a cathode using a carbon nanotube film, and an anode provided with red, green, and blue phosphors is further disposed above the cathode. Such a structure including the cathode, the gate and the anode is called a triode structure. A voltage is applied to the gate to extract electrons from the carbon nanotube, which is the cathode, and irradiate the anode to cause the phosphor to develop color.However, an insulating film is formed on the cathode, a cathode hole is further formed, and holes on the insulating film are formed. By forming a gate electrode around the gate, a structure in which electrons are not injected into the gate can be formed. In the FED, a plurality of the triode structures are further formed and basically operated independently to express an image. For this purpose, a fine pattern of a carbon nanotube film is required, and it is necessary to operate independently electrically. is there. The anode electrode is FED
In the following, a triode structure is a structure mainly composed of a cathode mainly composed of carbon nanotubes, an insulating film, and a gate electrode because it is separately formed on the facing glass.

Japanese Patent Laid-Open No. 2000-2038 discloses a method for forming a carbon nanotube film into a predetermined pattern.
In No. 21, after a substrate was patterned in a predetermined pattern using an adhesive tape and put into a solution in which carbon nanotubes were dispersed, and the solution was spontaneously evaporated, the carbon nanotubes were deposited on the substrate. A method of obtaining a carbon nanotube film having a predetermined pattern by peeling an adhesive tape is disclosed. More specifically, a copper plate on which an adhesive tape is adhered in a predetermined pattern is put into a beaker together with a solution in which carbon nanotubes are dispersed, and the solution is evaporated to laminate the carbon nanotubes on the copper plate. The pattern is formed by peeling off the tape.

JP-A-6-252056 discloses that carbon nanotubes are dispersed in a resist and coated on a substrate.
A method is disclosed in which, after exposure and development to a predetermined pattern, a fixing material is adhered onto the carbon nanotubes, thereby fixing the carbon nanotubes to the substrate, and further lifting off the resist, leaving only the carbon nanotubes and the fixing material. ing.

SID'99 Digest, p1137 (1999) and SID'00
Digest, p329 (2000) reports a method of forming carbon nanotubes on cathode metal wiring by screen printing.

Feng-Yu Chuang, SID00 Digest, p329 (2000)
Describes a method of forming a slurry containing carbon nanotubes and a binder by screen printing as an electron source of FED.

[0013]

SUMMARY OF THE INVENTION However, Japanese Patent Application Laid-Open
According to the method disclosed in 000-203821, carbon nanotubes are intricately entangled because they are very high aspect ratio tubular materials having a diameter of several nm to several tens of nm and a length of several μm. The carbon nanotubes deposited by spontaneous evaporation on the substrate to which the tape is attached have a problem in that the edges are entangled, turned up, or protruded when the tape is peeled off, so that a beautiful pattern cannot be formed. In other words, since the carbon nanotubes have a length of several μm, the carbon nanotubes on the substrate and the carbon nanotubes on the adhesive tape are entangled and deposited when spontaneously evaporated. Then, the carbon nanotubes on the substrate were peeled off at the same time, or the carbon nanotubes remained on the portion where the adhesive tape was peeled off. Further, it was difficult to obtain a flat carbon nanotube film because the solvent was not uniformly evaporated in the carbon nanotube film formed by natural evaporation.

According to the method disclosed in JP-A-6-252056, since the carbon nanotubes are dispersed in a resist and patterned, the content of the carbon nanotubes cannot be made too high in order to prevent the photosensitivity from being lost. There is a problem that the density of carbon nanotubes in the obtained film is reduced.

SID'99 Digest, p1137 (1999) and SID'00
According to the method of forming a pattern using screen printing reported in Digest, p329 (2000), it is necessary to mix a solvent or a binder to form an ink in order to perform screen printing. Kaihei 6-2
The density of the carbon nanotubes in the obtained film was reduced as in the case of No. 52056. In addition, it is difficult to volatilize the solvent in the ink uniformly, and there is a problem that minute irregularities are generated in the carbon nanotube film due to, for example, generation of a cavity in a portion from which the solvent has escaped.

Feng-Yu Chuang, SID00 Digest, p329 (2000)
In the screen printing method described in (1), it is possible to form a pattern of about several hundreds of micrometers, but it is difficult to form a fine pattern of several tens of micrometers or less.

The present invention has been made in view of the above-mentioned circumstances, and enables a fine pattern of a carbon nanotube film to be easily formed, a good flatness, and a good shape of a pattern end portion. It is an object of the present invention to provide a method capable of forming a carbon nanotube pattern with improved reliability in insulation between layers.

[0018]

The present invention provides the following methods (1) to (14) for forming a carbon nanotube pattern in order to achieve the above object.

(1) A carbon nanotube entangled with a binder, which is fixed on a substrate or a substrate having a thin film on at least a part of its surface, is removed through a mask formed in a predetermined pattern. A method for forming a pattern of carbon nanotubes, wherein a solution for dissolving the binder is used for removing the carbon nanotubes, and the entangled carbon nanotubes are scraped off.

(2) The cloth used for removal is contained in a cloth-like substance, and the carbon nanotube is removed by rubbing the carbon nanotube with the cloth-like substance, and the carbon nanotube is rubbed off with the cloth-like substance ( 1) A method for forming a pattern of carbon nanotubes.

(3) The method of (1) or (2), wherein the mask is made of metal, glass or ceramics.

(4) The method for forming a carbon nanotube pattern according to any one of (1) to (3), wherein the carbon nanotube is a nanotube containing nanoparticles.

(5) The pattern of the carbon nanotubes is removed by removing a part of the carbon nanotubes fixed on the substrate or on the substrate having a thin film on at least a part of the surface by the first dry etching method. A method of forming a carbon nanotube pattern using a metal film or a film of a material that is not damaged during the first dry etching and that does not damage the carbon nanotube when removing the mask, as a mask in forming a pattern of carbon nanotubes. A method for forming a pattern of carbon nanotubes, characterized in that:

(6) The method of forming a pattern of carbon nanotubes, wherein the first dry etching method is a method of burning in an oxygen atmosphere.

(7) The method of (5) or (6), wherein the metal film is an aluminum film, a titanium film, a gold film, a molybdenum film, a tungsten film or a silver film.

(8) The film of a material which is not damaged during the first dry etching and which does not damage the carbon nanotubes during removal is a silicon dioxide film or an aluminum oxide film (5) or (6). Method for forming a pattern of carbon nanotubes.

(9) The method of forming a carbon nanotube pattern according to (5) to (8), wherein the carbon nanotube is a single-wall nanotube or a multi-wall nanotube.

(10) The method for forming a carbon nanotube pattern according to (9), wherein the single-wall nanotube or the multi-wall nanotube is a purified nanotube from which nanoparticles are removed.

(11) The carbon nanotubes are nanotubes containing nanoparticles, and the nanoparticles remaining between the carbon nanotube patterns are removed by lifting off at least a part of the thin film (1) to (9). A method for forming a carbon nanotube pattern.

(12) The carbon nanotube is a nanotube containing nanoparticles, and the nanoparticles remaining between the carbon nanotube patterns are removed by a second dry etching method different from the first dry etching (5). (9) The method for forming a carbon nanotube pattern according to (9).

(13) The second dry etching method is any one of sputter etching, chemical etching, reactive etching, reactive sputter etching, ion beam etching, and reactive ion beam etching. (12) The method for forming a carbon nanotube pattern according to (12), wherein a catalyst metal constituting a part thereof is removed.

(14) The method for forming a carbon nanotube pattern according to any one of (1) to (13), wherein the carbon nanotube film is formed by a screen printing method, a spray method or a transfer method.

[0033]

Embodiment 1 Embodiment 1 of the present invention will be described with reference to FIGS. FIG. 1 shows a state in which a single-wall nanotube film 6 is formed on a conductor wiring 4 formed on a substrate 2 by, for example, a transfer method.

In the transfer method, first, ultrasonic waves or the like are applied to disperse carbon nanotubes in a solvent. As a result, the nanotubes are finely divided and divided. Next, the mixture is poured onto a filter paper and filtered by suction to form a carbon nanotube thin film. Nitrocellulose or ethylcellulose is applied to the substrate as a binder, and the carbon nanotube film on the filter paper is transferred upside down to the substrate. Next, the filter paper is removed to form a thin film. Since the surface of the carbon nanotube film is in contact with the surface of the filter paper, it has the same flatness as the surface of the filter paper.

In this carbon nanotube film, tubular carbon nanotubes having a diameter of several nm to several tens of nm and a length of several μm and having a very high aspect ratio are intricately entangled with each other.

In this embodiment, as shown in FIG. 2, a mask 8 made of metal, glass, ceramics, or the like is arranged so as to be aligned with the underlying conductor wiring 4. Here, by using the alignment mark 10 formed in a portion outside the carbon nanotube region for disposing the mask, the conductor wiring and the mask can be easily aligned.

Subsequently, as shown in FIG. 3, the rubbing is carried out using an etching solution for dissolving the binder component used for forming the carbon nanotube film 6, for example, a cloth material 12 such as glass fiber containing methyl ethyl ketone. The entangled carbon nanotubes and nanoparticles are removed, and the carbon nanotube film is patterned. Because the carbon nanotube film obtained by the transfer method is very dense, the part covered with the mask is
Even if the substrate is rubbed with a cloth material containing an etching solution, it remains fixed on the conductor wiring without being dissolved.
FIG. 4 shows the shape after patterning the carbon nanotube film.

Although the transfer method has been described as a method of forming a carbon nanotube film, the present invention can be similarly applied to the formation of a pattern on a carbon nanotube film formed by a method such as screen printing or spraying.

When a cellulose-based fixing material such as nitrocellulose is used in the transfer method, the solvent, for example, methyl ethyl ketone, has high volatility and is easily removed from the film. Removed. When an electron is emitted by applying an electric field to the carbon nanotube film, ionization of the residual gas is suppressed because the residual volatile substances have been removed. Therefore, abnormal discharge due to discharge and element destruction due to the discharge are suppressed, and the life of the display can be extended.

In the transfer method, the density of the carbon nanotube film is higher than in other film forming methods, and the surface in contact with the flat filter paper at the time of suction becomes the upper surface, so that the surface becomes flat. When an insulating film and a gate film are formed thereon, a stable triode structure is easily formed as compared with other methods. On the other hand, in the printing method, a pattern can be formed at the time of printing by forming the pattern on a screen. However, it is necessary to mix the paste, and the density of the carbon nanotubes is low and the surface becomes rough as compared with the transfer method. When an insulating film and a gate film are formed thereon, it is difficult to form a stable triode structure. As described above, when the present invention is applied to the carbon nanotube film formed by the transfer method, good element separation is possible, and a stable triode structure can be formed.

The carbon nanotubes and the nanoparticles are removed by using a cloth material 12 such as glass fiber containing a solvent. However, other methods such as brushing or brushing while spraying the solvent are used. Scrubbing is also possible. However, a cloth-like substance easily contains a highly volatile solvent, and its shape can be deformed according to a pattern, and it can be pressed at the same time. Therefore, a dense carbon nanotube film such as a sample prepared by a transfer method can be used. Preferred for removal.

In addition, since extra force is applied to the mask in addition to the nanotubes during the rubbing, metal, glass, and ceramic are preferable instead of a mask material that is easily deformed or crushed, such as a resist or a tape. In particular, when an organic substance or the like is separated and remains in the emitter portion, gas is released during the FED operation, the degree of vacuum is deteriorated, ionization of the residual gas occurs, and abnormal discharge due to discharge occurs. Such problems do not occur in metals, glasses, and ceramics. In particular, metal can be formed into a thin film while maintaining strength, and is most preferable.

The present embodiment can be applied to a purified carbon nanotube film. However, when purified nanotubes are rubbed with a cloth material soaked in a solvent,
Swelling and deformation are observed when the purified nanotubes contain a solvent. Therefore, the slid end of the nanotube swells, deforms, and the pattern deteriorates.
In some cases, cracks occur during drying. On the other hand, the nanotubes that are not purified hardly swell or deform. This is because the nanotubes are entangled with each other due to the particles to form a strong film.

[0044] Therefore, unpurified nanotubes are preferable because they cost less and do not easily deteriorate the patterning shape as compared with purified nanotubes.

Embodiment 2 Embodiment 2 of the present invention will be described with reference to FIG. FIG. 5A is a cross-sectional view after the metal cathode wiring 24 is formed in a stripe pattern on the glass substrate 22. As a method of forming the cathode wiring, for example, a metal film is formed on the entire surface of a glass substrate by a method such as evaporation, sputtering, or CVD, and a resist is applied.
There is a method in which a metal film is etched and then the resist is peeled off.

Subsequently, as shown in FIG. 5B, a multi-wall nanotube, a single-wall nanotube formed using a catalytic metal by arc discharge, or a single-wall nanotube from which the catalytic metal has been removed is mixed with an organic binder. The carbon nanotube film 26 is formed on the entire substrate of (1) of No. 5. As a method for forming the carbon nanotube film, for example, there is a transfer method.

Subsequently, as shown in FIG. 5C, an aluminum film 28 serving as a mask is formed on the carbon nanotube film 26 of FIG. 5B, and then a pattern is formed on the aluminum film. For this purpose, a resist 30 is applied.

Subsequently, as shown in FIG. 5 (4), the resist 30 is exposed and developed in a stripe shape together with the cathode wiring pattern 24.

Subsequently, as shown in FIG. 5E, the aluminum film 28 is etched using the patterned resist 30 as a mask.

Subsequently, the resist is peeled off as shown in FIG.

Subsequently, as shown in FIG. 5 (7), the carbon nanotube film exposed on the surface is removed by burning using a dry etching apparatus, for example, an O ₂ plasma ashing apparatus. Here, the term “combustion” includes not only the case of raising the sample temperature but also a method of oxidizing with activated O ₂ plasma and radicals without raising the substrate temperature, that is, ashing.

Finally, as shown in FIG. 5 (8), the aluminum film on the carbon nanotube film 26 is removed by wet etching with phosphoric acid, particularly heated phosphoric acid, so that the carbon nanotube film is patterned on the cathode wiring 24. it can.

In the patterned carbon nanotube film formed in this embodiment, microscopic changes were not observed even by observation with an electron microscope as compared with the nanotube film before patterning, and the same emission current was observed. It was found that there was no damage even if the aluminum film was removed. FIG. 5 (9) is a perspective view of FIG. 5 (8).

Since the pattern of the carbon nanotubes obtained in this embodiment is formed by burning using the aluminum film as a mask, the carbon nanotubes at the pattern end portions are not entangled with each other, and a good shape is obtained.

Although this embodiment has been described using O ₂ plasma ashing, other dry etching methods such as sputter etching, chemical etching, reactive etching, reactive sputter etching, ion beam etching, and reactive ion Etching by beam etching is possible.

Gas etching or radical-containing etching is chemical etching or reactive etching, and can remove carbon nanotubes or nanoparticles mainly composed of carbon by using a reactive gas such as oxygen or hydrogen which can be removed by reacting with carbon. Carbon bonds of carbon nanotubes or carbon nanoparticles, and amorphous carbon covering the catalytic metal surface are composed of 6-membered rings or 5-membered rings. The bond is incomplete, has many 5-membered rings, and easily reacts with a reactive gas.

Therefore, in the case of patterning carbon nano particles and carbon nanotubes containing amorphous carbon covering the catalytic metal surface, gas etching or etching containing radicals is more effective. Furthermore, since gas etching or etching containing radicals is isotropic etching, not only the surface of the nanotube to be patterned, but also the reactive gas flows to the nanotubes near the surface, the sidewalls and the back surface of the nanoparticles, and the selection is made. Reactively reacts with carbon, and can quickly remove non-catalytic metals. By adding a step of removing only the catalyst metal described later, the carbon nanotubes containing nanoparticles can be patterned. For example, in the case of oxygen, the reaction product becomes a gas such as CO or CO _2, so that it does not adhere again to the substrate, and there is no problem of surface contamination. In particular, combustion using oxygen is simple and preferable.

Next, the case where the ionic sputtering effect is used will be examined. In the second embodiment, the carbon nanotubes to be left during patterning are coated with aluminum by using, for example, sputtering or vapor deposition. However, the surface of the carbon nanotubes has large irregularities, and there are cases where the aluminum cannot be sufficiently covered particularly inside the concaves. is there. When a reactive gas is used, the gas wraps around, and when the etching time is long, the carbon nanotubes are etched from portions where the protective film is not sufficiently covered. On the other hand, when ionic sputter etching is used, the ionic species have high rectilinearity and the ionic species enter from the upper surface, so that the carbon nanotubes located under the thick coating film are not easily damaged. Further, since the etching is anisotropic, the etching can be performed faithfully and vertically to the mask pattern. Therefore, it is preferable to remove a carbon nanotube film that does not contain catalytic metal among the nanoparticles, and it is also preferable to form a fine pattern.

In ion beam etching and reactive ion beam etching, etching can be performed without a mask, but the beam needs to be modulated, and a process time per area is required. Suitable for small displays rather than large area displays.

In this embodiment, an example is shown in which an aluminum film is used as a mask during O ₂ plasma ashing, but a metal that does not damage the carbon nanotubes during removal, such as titanium, gold, molybdenum, tungsten, Silver or the like may be used. Nitric acid for titanium,
Gold can be aqua regia, molybdenum can be quickly removed by hot concentrated sulfuric acid or aqua regia, and tungsten can be quickly removed by a mixed solution of hydrofluoric acid and nitric acid. However, since carbon nanotubes gradually deteriorate with nitric acid, sulfuric acid, and hydrogen fluoride in a long-term treatment, conditions that do not suffer from damage, especially emission deterioration in the case of FED, particularly, temperature, concentration and a predetermined time Need to be processed within. Nitric acid 6 at room temperature
5%, 90% sulfuric acid, 45% hydrogen fluoride, and a mixture thereof can be treated without damage within one hour. Aluminum is inexpensive compared to other metals, and the coating state of carbon nanotubes, especially the aluminum crystal grains are dense and the coverage is high, and the carbon nanotubes are not deteriorated with respect to the phosphoric acid as an etching solution. Preferred over other metals.

On the other hand, a metal having a large atomic weight has a small sputtering rate due to ions, and is suitable as a mask material in the case of dry etching mainly having a sputtering effect. In particular, gold, tungsten, and molybdenum are more than twice as resistant to spatter than aluminum and titanium, and are less susceptible to damage under the mask. Therefore, they are particularly useful for removing carbon nanotubes that do not contain catalytic metal among nanoparticles. It is preferable for fine pattern formation.

In addition to metals, any substance that does not suffer damage by O ₂ plasma ashing and does not damage the carbon nanotubes when removed, such as silicon dioxide or aluminum oxide, can be used. .

In the case of a metal, the conductivity is increased, and the metal can be used as a cathode electrode, which is advantageous because it is not necessary to separately form a cathode electrode. When a triode structure is formed by directly applying a gate metal, or by applying an insulating film and a gate metal, particularly in the case of an insulating film other than a metal, it can be used as an insulating layer between the gate metal and the cathode. In some cases, additional insulating film formation can be omitted,
The process can be simplified.

In this embodiment, the transfer method is used as the method for forming the carbon nanotube film shown in FIG. 5B. However, the carbon nanotube film can be easily formed by using a method such as screen printing. However, in the transfer method, the nanotube density is high, the nanotubes are entangled, and in the other patterning methods, the pattern ends are turned over or protruded, so that a clean pattern cannot be formed. A pattern can be formed, and a fine pattern of several tens μm or less can be formed.

On the other hand, as compared with the transfer method, the screen printing method and the spray method can easily form a thin film on the entire surface of a large area display of 30 inches or more, and in the first embodiment, a simple method is used. It is suitable for large displays for home use. In the second embodiment, a fine pattern can be formed, which is suitable for manufacturing a high-quality flat panel television or the like.

In this embodiment, as shown in FIG. 5 (6), a step of removing the resist on the aluminum film is included. However, even if the step of removing the resist is omitted, the resist is simultaneously removed in the subsequent O ₂ plasma ashing step. Therefore, even if the step of removing the resist is omitted, the pattern formation of the carbon nanotubes can be similarly performed.

Third Embodiment A third embodiment of the present invention will be described with reference to FIG. FIG. 6A is a cross-sectional view after a metal film 44 is formed on the entire surface of the glass substrate 42 by using a method such as evaporation, sputtering, or CVD.

Subsequently, as shown in FIG. 6B, the single-wall nanotube is mixed with, for example, an organic binder to form a carbon nanotube film 46.

Subsequently, as shown in FIG. 6C, an aluminum film 48 serving as a mask is formed on the carbon nanotube film 46, and then a resist 50 is applied on the aluminum film.

Subsequently, as shown in FIG. 6D, the resist 50 is exposed and developed in a stripe shape. Subsequently, the aluminum film 48 is etched using the resist as a mask.

Subsequently, as shown in FIG. 6 (5), the resist is stripped.

Subsequently, the carbon nanotube film 46 exposed on the surface of the substrate shown in FIG. 6 (5) is burned and removed using an O ₂ plasma ashing apparatus, thereby patterning the carbon nanotube film. For example, in the case of a single-wall nanotube, since impurities such as a catalyst metal are included in a large amount, impurities 52 such as a catalyst metal remain in a portion not masked by the aluminum film as shown in FIG. I do. The remaining impurities such as the catalyst metal cause an electrical short circuit between the patterns, which causes a malfunction in the case of the FED.

However, when the substrate is immersed in the etching solution of the underlying metal in this state, the patterned carbon nanotube film becomes a mask and the underlying metal is etched. At the same time, impurities such as the catalyst metal are lifted off and removed.

In the case of Example 1, even when the cloth is sufficiently pressurized and rubbed with a cloth-like substance containing an etching solution, nanoparticles and slight carbon nanotubes may remain. When the base metal is immersed in an etchant, the patterned carbon nanotube film serves as a mask, and the base metal is etched. At the same time, the nanoparticles are lifted off and removed.

Finally, the aluminum film for the mask is etched to form the pattern of the cathode wiring and the carbon nanotube film at the same time as shown in FIG.
FIG. 6 (8) is a perspective view of FIG. 6 (7).

Since the pattern of the carbon nanotubes obtained in this embodiment is formed by burning using the aluminum film as a mask, the carbon nanotubes at the pattern end portions are not entangled with each other, and a good shape is obtained.

In this embodiment, an example is shown in which a mixture of single-wall nanotubes and an organic binder is formed as a carbon nanotube film. The present invention can be applied to a case where the film is formed as a carbon nanotube film. In that case, the impurities such as the catalyst metal shown in FIG. 6 (6) are not exposed, and the underlying metal is etched using the patterned carbon nanotubes as a mask, and the aluminum film for the mask is etched. 6
As shown in (7), the cathode wiring and the carbon nanotube film can be formed at the same time, and the process can be simplified compared with the case of using the carbon nanotube film containing nanoparticles, which is advantageous.

Fourth Embodiment Next, a fourth embodiment will be described. In Example 3, when carbon nanotubes containing carbon nanoparticles were subjected to O ₂ plasma treatment, as shown in (6) of FIG.
An impurity 52 such as a catalyst metal remains. Thereafter, it is possible to dry-etch the catalytic metal by further changing the gas type. The catalyst metal is iron, nickel, cobalt, yttrium, lanthanum, etc., but can be sputtered by an ionic gas such as milling.

Further, a reactive gas, particularly a halogen-based gas, for example, chlorine, hydrochloric acid, boron trichloride, sulfur hexafluoride, bromohydride or the like can be used to improve the reactivity to remove the catalytic metal. . Further, ionic etching is more effective together with reactive gas species such as radicals. The reactivity can be improved to promote the reaction, and the reaction product can be removed from the surface by sputtering with an ionic gas.

When an aluminum film is used as a mask material as described in the third embodiment, it may be necessary to change a mask material such as a resist or the like which has selectivity for a catalyst metal or to add patterning. However, in place of the aluminum film, a metal having a large atomic weight resistant to sputtering, for example, gold, molybdenum, tungsten, or the like, is used. There is no change or the like and no additional process, which is preferable as compared with aluminum.

When the aluminum film is used as it is,
The aluminum film is also removed. However, if the exposure time of the carbon nanotube is adjusted to be short to suppress the deterioration, the patterned carbon nanotube is formed without a step of separately removing the aluminum film.

When removing the catalytic metals iron, nickel, cobalt, yttrium and lanthanum using a reactive gas, particularly a halogen-based gas, the removal can be accelerated by heating the substrate, which is effective. The halogen compound of the catalyst metal has a low vapor pressure at room temperature, but the vapor pressure can be increased by heating to accelerate the removal.

[0083]

As described above, according to the method for forming a carbon nanotube pattern according to the present invention, a fine pattern of a entangled carbon nanotube film can be easily formed. It is possible to form a carbon nanotube pattern with good pattern end shape and good reliability in insulation between elements.

[Brief description of the drawings]

FIG. 1 is a view showing a process of Example 1.

FIG. 2 is a view showing a process of Example 1.

FIG. 3 is a view showing a process of Example 1.

FIG. 4 is a diagram showing a process of Example 1.

FIG. 5 is a view showing a process of Example 2.

FIG. 6 is a view showing a process of a third embodiment.

[Explanation of symbols]

 2 Substrate 4 Conductor wiring 6 Single wall nanotube film 8 Mask 12 Cloth material 22 Glass substrate 24 Cathode wiring 26 Carbon nanotube film 28 Aluminum film 30 Resist 42 Glass substrate 44 Metal film 46 Carbon nanotube film 48 Aluminum film 50 Resist 52 Impurity

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Fuminori Ito 5-7-1 Shiba, Minato-ku, Tokyo Inside NEC Corporation (72) Inventor Kazuo Onuma 5-7-1 Shiba, Minato-ku, Tokyo Japan Inside Electric Co., Ltd. (72) Inventor Akihiko Okamoto 5-7-1 Shiba, Minato-ku, Tokyo F-term (Reference) 4G046 CC01 CC10

Claims (14)

[Claims] An entangled carbon nanotube containing a binder, which is fixed on a substrate or a substrate having a thin film on at least a part of its surface, is removed through a mask formed in a predetermined pattern. A method for forming a pattern of carbon nanotubes by using a solution dissolving the binder for removing the carbon nanotubes, and scraping the entangled carbon nanotubes. 2. A solution used for removal is contained in a cloth material,
The carbon nanotube pattern forming method according to claim 1, wherein the carbon nanotubes are removed by rubbing the carbon nanotubes with the cloth-like substance, and the carbon nanotubes are rubbed off with the cloth-like substance. 3. The method according to claim 1, wherein the mask is made of metal, glass or ceramic. 4. The method for forming a carbon nanotube pattern according to claim 1, wherein the carbon nanotube is a nanotube containing nanoparticles. 5. A pattern of carbon nanotubes is formed by removing a portion of carbon nanotubes fixed on a substrate or a substrate having a thin film on at least a part of its surface by a first dry etching method. Using a metal film or a material that does not damage the carbon nanotubes during the first dry etching, and that does not damage the carbon nanotubes when removing the mask, as a mask for forming the carbon nanotube pattern. Characteristic carbon nanotube pattern forming method. 6. The method for forming a carbon nanotube pattern according to claim 1, wherein the first dry etching method is a method of burning in an oxygen atmosphere. 7. The method for forming a carbon nanotube pattern according to claim 5, wherein the metal film is an aluminum film, a titanium film, a gold film, a molybdenum film, a tungsten film or a silver film. 8. The film according to claim 5, wherein the film of the material that is not damaged during the first dry etching and that does not damage the carbon nanotube during the removal is a silicon dioxide film or an aluminum oxide film. A method for forming a carbon nanotube pattern. 9. The method for forming a carbon nanotube pattern according to claim 5, wherein the carbon nanotube is a single-wall nanotube or a multi-wall nanotube. 10. The method according to claim 9, wherein the single-wall nanotube or the multi-wall nanotube is a purified nanotube from which nanoparticles have been removed. 11. The carbon nanotube according to claim 1, wherein the carbon nanotube is a nanotube containing nanoparticles, and the nanoparticles remaining between the carbon nanotube patterns are removed by lifting off at least a part of the thin film. Method of forming nanotube pattern. 12. The carbon nanotube is a nanotube containing nanoparticles, and the nanoparticles remaining between the carbon nanotube patterns are removed by the first carbon nanotube.
10. The method for forming a pattern of carbon nanotubes according to claim 5, wherein the carbon nanotubes are removed by a second dry etching method different from the dry etching method. 13. The method of claim 2, wherein the second dry etching method is any one of sputter etching, chemical etching, reactive etching, reactive sputter etching, ion beam etching, and reactive ion beam etching.
The method for forming a pattern of carbon nanotubes according to claim 12, wherein a catalyst metal constituting at least a part of the nanoparticles is removed. 14. The method for forming a carbon nanotube pattern according to claim 1, wherein the carbon nanotube film is formed by a screen printing method, a spray method, or a transfer method.