JP2014172792A - Patterned aromatic carbon film and method for manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing a patterned aromatic carbon film capable of simultaneously realizing high electroconductivity and light permeability when used for at least partially constituting a transparent electroconductive film and of executing a patterning work at a narrow line width; an aromatic carbon film patterned at a narrow line width and having homogeneous edges; and a transparent electroconductive composite.SOLUTION: The provided method for manufacturing a patterned aromatic carbon film includes a patterning work of forming a thin film including at least one type of metal species on the surface of an aromatic carbon film based on ion plating and then treating the thin film with an acidic liquid.

Description

  The present invention relates to a patterned aromatic carbon film and a method for producing the same. More specifically, the present invention relates to an aromatic carbon film having a uniform end and a pattern processing with a narrow line width, which can achieve both high conductivity and light transmittance when used in a transparent conductive film, and an end. The present invention relates to a method for producing an aromatic carbon film having a uniform pattern and capable of patterning with a narrow line width and capable of processing with a large area.

  The transparent conductive film uses a unique property of being transparent and having high electrical conductivity (conductivity), and is a multi-function mobile phone that is becoming mainstream among current mobile phones, a touch panel that is an important input device of a so-called smartphone, Widely used as transparent electrode members such as electronic paper, solar cells, and organic LEDs. A metal material such as indium tin oxide (ITO) has been used for a long time as a suitable material that achieves both high permeability and low electrical resistance for the material of the conventional transparent conductive film. However, since it is a metal-based material, there are inevitable problems such as that the weight per unit area of the transparent conductive film tends to be large, cracking is likely to occur due to slight bending and vibration during transportation, and also worldwide. Although the distribution of ore produced is limited and recycling technology is being established, supply and demand and prices are susceptible. Therefore, there is a need for a new material search for transparent conductive films that can replace these metal-based materials.

  Graphite has long been known as a carbon material with excellent electrical conductivity and has been used in various ways. In recent years, carbon nanotubes, which are new allotropes of graphite, and graphite sheets obtained by carbonizing and firing resin materials are similar to graphite. As a highly conductive material, it is being used in a wide range of applications. Recently, an aromatic carbon film having a graphene structure in which a large number of benzene ring structures having a thickness on the order of nanometers, which forms a part of graphite, is spread in the plane direction is derived from high conductivity and very thin It is becoming known as a material that achieves both light transmission properties, and research and development has been activated in order to use it as a new material for a transparent conductive film that replaces metallic materials such as ITO.

  Aromatic carbon membranes have many excellent properties such as high strength / high modulus of elasticity and high mobility in addition to high conductivity and high transmittance, but also have a chemically stable structure. Is becoming very bad. This relates to the use of the transparent conductive film particularly for the touch panel, and it is easily assumed that the patterning of the aromatic carbon film is very difficult. By the way, the metal material which is the mainstream of the conventional transparent conductive film has a feature that it is easily dissolved in an acidic aqueous solution. Therefore, in patterning required for application to an electrode member, a chemical treatment in which etching is performed with an acidic aqueous solution. Therefore, patterning with a desired design is easy, which is one of the reasons why metal-based materials are widely used. That is, in order for an aromatic carbon film to replace a metal material and be widely used for a transparent conductive film, an easy patterning technique is also indispensable.

Some attempts have been made to pattern the above-mentioned problem, that is, a chemically stable aromatic carbon film. For example, a technique is disclosed in which oxygen atoms are bonded to an aromatic carbon film in advance and then patterned by etching with a laser (see, for example, Non-Patent Document 1). In this technique, the carbon atoms in the carbon film to which oxygen atoms are bonded are changed from a stable sp ² structure to an sp ³ structure and easily etched with an argon laser, and a mask is not required for patterning. There is. However, on the other hand, since the laser has an intensity distribution in the width direction, the aromatic carbon film is formed of a plurality of layers of graphene, and when the thickness is, the etching end is not necessarily etched at the same position, It will have a certain width. Therefore, in the etching with laser, it is necessary to scan the same portion many times so that the processing lines overlap. In addition, since all patterning is performed by laser delineation, the patterning rate per unit area tends to decrease according to the density of the patterning design. In addition, the carbon film removed by the argon laser tends to remain around the removal position as unnecessary dust, and it is difficult to completely remove it. Furthermore, when the carbon film is supported on an organic substrate such as a plastic film. As described above, the substrate itself is easily damaged by deformation, coloring, and the like by scanning the same portion many times as described above, and there are many problems as a patterning technique as a whole.

  In addition, a technique for patterning an aromatic carbon film by carrying a thin film made of a metal-based material through a mask on an aromatic carbon film formed of one graphene layer or a plurality of graphene layers (for example, non-patent) is disclosed. Reference 2). In this technique, an aromatic carbon film previously transferred onto a substrate is loaded with a metal such as zinc or copper having a thickness of several nanometers using a mask by sputtering, and then the metal is dissolved and removed with dilute hydrochloric acid. Thus, the aromatic carbon film is etched and patterned. Although this technique has the merit that the graphene constituting the aromatic carbon film can be peeled one layer at a time in the steps of supporting the metal film and dissolving and removing with a dilute acid, the fragrance composed of multiple layers of graphene having excellent conductivity In the case of a group carbon film, in order to remove all the graphene layers, it is necessary to repeat the above-mentioned metal film support and dissolution / etching with dilute acid according to the number of layers as many times as the number of layers. In addition, in order to perform patterning accuracy or high-density patterning with respect to patterning, it is necessary to carry a metal film by placing a mask at the same position of the aromatic carbon film every time. In the case of a carbon film composed of layers, the feasibility is low, and the technique is generally difficult to apply industrially.

“Atomic layer etching of graphene for full graphene device fabrication”, Carbon, 2012, No. 50, p. 429-435 “Layer-by-Layer Removable of Graphene for Device Patterning”, Science, 2011, No. 331, p. 1168-1172

  As described above, regarding the etching and patterning technology of the aromatic carbon film, a technology that can be used in terms of patterning accuracy and density or industrial value has not been established. In other words, when using an aromatic carbon film consisting of multiple layers of graphene with high conductivity and high transmittance, high-accuracy patterning that can be applied without sacrificing the processing speed is possible even for large-area carbon films. In order to solve the above-mentioned problems, the present inventors have developed an aromatic carbon film composed of a plurality of layers of graphene in an aromatic carbon film etching and patterning technology that can be achieved with a small number of industrially valuable processes. We have worked hard to make it possible to easily pattern a large-area carbon film by establishing a method that can etch the film at once.

  That is, an object of the present invention is an aromatic carbon film that can achieve both high conductivity and light transmittance when used for at least a part of a transparent conductive film, and has a pattern processing with a uniform end and a narrow line width. Another object of the present invention is to provide a conductive resin film using the carbon film and a method for producing a patterned aromatic carbon film that can be patterned with a narrow line width and can be processed over a large area.

  The present invention employs the following configuration in order to solve the above problems.

  (1) A pattern comprising pattern processing for forming a thin film containing at least one metal species on the surface of an aromatic carbon film by ion plating and then treating the thin film with an acidic liquid. A process for producing a processed aromatic carbon film.

  (2) The method for producing an aromatic carbon film obtained by patterning according to the above (1), wherein the aromatic carbon film is made of a plurality of layers of graphene.

  (3) The method for producing an aromatic carbon film obtained by patterning according to (2), wherein the number of graphene layers is 2 to 30.

  (4) The fragrance formed by pattern processing according to any one of (1) to (3), wherein the metal species is selected from at least one of the first transition element, the second transition element, and the third transition element. A method for producing a group carbon film.

  (5) The method for producing an aromatic carbon film obtained by patterning according to any one of (1) to (4), wherein the acidic liquid is selected from at least one of hydrochloric acid, sulfuric acid, and nitric acid.

  (6) The method for producing an aromatic carbon film obtained by patterning according to any one of (1) to (5), wherein the hydrogen ion exponent (pH) of the acidic liquid is 2.0 or less.

  (7) A patterned aromatic carbon film characterized in that the pattern end faces of all the layers constituting the aromatic carbon film are formed with a width of 10 micrometers or less.

  (8) A conductive transparent composite comprising at least a part of the aromatic carbon film subjected to pattern processing according to (7).

  In the production method of the present invention, the patterning of the aromatic carbon film composed of a plurality of layers can be achieved by a single treatment, that is, a single ion plating (hereinafter sometimes referred to as IP) and an acidic liquid treatment. Compared to the conventional etching method, the number of processes is greatly reduced and the processing can be performed in a short time, and the industrial utility value is high. In particular, the aromatic carbon film is formed as a transparent conductive composite and requires a large area when used for an electrode such as a touch panel or a solar cell. Therefore, even when the aromatic carbon film is supported on an organic substrate such as a plastic film, deformation and coloring are hardly caused, which is an excellent technique.

  The aromatic carbon film of the present invention is patterned, and the pattern end faces are aligned with a very narrow width, that is, the end faces of all layers constituting the aromatic carbon film are formed with a width of 10 micrometers or less. ing. Therefore, when the transparent conductive composite having the aromatic carbon film supported at least in part is used by patterning, the line width of the aromatic carbon film can be narrowed or the aromatic carbon film is removed. Since sufficient insulation can be ensured even if the width is narrowed, the patterning design density can be increased, resulting in higher complexity and higher functionality. That is, when forming a touch panel, it can be used as an excellent transparent conductive film that can exhibit highly accurate reaction responsiveness.

  The transparent conductive composite carrying the aromatic carbon film of the present invention at least partially has high conductivity and high light transmittance, and has an excellent transparent electrode when used in the above-mentioned touch panel and solar cell. Can be configured. In particular, the aromatic carbon film has high conductivity similar to that of a metal-based material such as conventional ITO, and is not cracked, and has flexibility that is impossible for the metal-based material. Therefore, it is resistant to deformation such as bending, greatly contributes to improving process passability and yield, and can replace metal-based transparent conductive materials.

It is explanatory drawing which shows the widest width | variety of the end surface of each layer in a process part end surface, and the pattern processing end surface when the aromatic carbon film in this invention is patterned.

  The aromatic carbon film of the present invention is a sheet-like graphene in which a plurality of hexagonal benzene ring lattice structures formed by π bonds of carbon atoms are gathered in a planar direction like a honeycomb, at least two or more layers. Layers are stacked. When a plurality of layers are stacked, each layer may be independent, or may be connected between the layers via a covalent bond or a non-covalent bond.

  The sheet-like graphene laminated with a very large number of layers is light as long as it is thin as long as it does not impair electrical conductivity, and the thickness is preferably 0.6 to 10 nm. More preferably, it is 0.6-7 nm, and it is especially preferable that it is 0.6-5 nm. And since it is desirable that the number of graphene layers constituting the aromatic carbon film satisfying these is as small as possible within the range not impairing the conductivity, the number of layers is preferably 2 to 30, and preferably 2 to 20 It is preferable and it is especially preferable that it is 2-15. The thickness of the aromatic carbon film and the number of graphene layers constituting the carbon film will be described later. As described in the section, it can be measured with a transmission electron microscope.

Further, the graphene structure composed of the hexagonal benzene ring lattice may contain foreign elements other than carbon atoms, for example, boron (B), nitrogen (N), oxygen (O), etc., especially 10% or less as doping. May be included in the atomic fraction. The analysis of foreign elements other than the carbon atom is described later in D.C. It can be performed by the method of the item. The aromatic carbon film in the present invention has high conductivity and light transmittance, and can be produced by various methods. Specifically, there is a thermal CVD method, in which a methane or other hydrocarbon gas, hydrogen gas, rare gas such as argon or helium is supplied at a constant rate in a high vacuum of 100 Pa or less. Usually, it is synthesized on the substrate while heating the atmosphere within a range of 500 ° C. to 1200 ° C. In addition, a gas containing a different element other than a carbon atom such as nitrogen or ammonia may be used as the gas. Further, as the substrate, a foil mainly composed of metal using a single or a plurality of transition metals such as iron, nickel, cobalt, and copper can be used, but a silicon substrate such as SiO ₂ or SiO ₂ / Si, aluminum oxide (Al _{A 2} O ₃ ) -based substrate is also preferably used.

  In addition to the thermal CVD method, the aromatic carbon film can be formed by a plasma CVD method. In this method, electromagnetic waves such as microwaves or several kV or more are supplied in a high vacuum atmosphere while supplying a constant ratio of methane or other hydrocarbon gas, hydrogen gas, rare gas such as argon or helium as in the thermal CVD method. An aromatic carbon film is synthesized on the aforementioned substrate while applying a high voltage of In the case of the plasma CVD method, the substrate is affected by ions or neutrons derived from gas generated in the plasma, and is substantially exposed to heating. However, a heating source is installed at the lower part of the substrate, and usually 100 ° C. to 1000 ° C. You may heat in the range of ° C.

  In addition to the above CVD methods, the aromatic carbon film can also be produced by incinerating a film-like resin after infusibilizing it in a very high temperature inert atmosphere. As the type of polymer, polyacrylonitrile-based polymer, cellulose-based polymer, polyamide-based polymer, polyimide-based polymer, phenol-based polymer, pitch, etc. can be used, and after infusibilizing at a temperature of usually 1000 ° C. or lower, 3500 ° C. An aromatic carbon film is obtained by baking at the following temperature.

  The thickness of the film-like resin is determined in consideration of the residual carbonization rate at the time of forming the aromatic carbon film. If the film is excessively thick, the aromatic carbon film is also thick and the light transmittance tends to be low. If it is thin, it tends to disappear without forming an aromatic carbon film. Therefore, it is preferably in the range of 5 nm to 10 μm, and particularly preferably in the range of 10 nm to 1 μm.

  In addition, the aromatic carbon film may be formed by laminating a large number of extremely fine graphene or exfoliated graphite in the plane direction. There are several methods for laminating and laminating a large number of ultra-fine graphene or exfoliated graphite, and there are methods of spraying ultra-fine graphene or exfoliated graphite in a powder form and laminating them on the substrate, A dispersion in which graphene or exfoliated graphite is dispersed in an aqueous or organic solvent is applied onto the substrate by spraying, spin coating, dipping (dipping), Layer-by-Layer method, or the like. After that, the solvent of the dispersion liquid is vaporized and evaporated to disappear, so that very fine graphene or exfoliated graphite is spread on the substrate and laminated.

  At this time, the concentration of ultrafine graphene or exfoliated graphite in the dispersion is preferably 0.005 to 15% by weight in consideration of obtaining a homogeneously laminated layer. It is more preferably from 01% by weight to 10% by weight, particularly preferably from 0.05% by weight to 5% by weight. Further, the size in the planar direction of the ultrafine graphene or exfoliated graphite is preferably 10 nm to 50 μm, more preferably 20 nm to 10 μm, and particularly preferably 50 nm to 5 μm in terms of median value. The dispersion may contain a dispersing agent for more uniformly dispersing ultrafine graphene or exfoliated graphite.

  Here, a preferred method is described as a method of dispersing ultrafine graphene or exfoliated graphite in an aqueous or organic solvent. As a dispersion liquid in which ultrafine graphene or exfoliated graphite is dispersed, a Brodie method in which graphite is oxidized using concentrated potassium nitric acid as an oxidizing agent in concentrated nitric acid and then treated with water, or a mixed solution of nitric acid and sulfuric acid is mixed with graphite. Staudenmeier method in which chlorate is added and oxidized with potassium chlorate, Hummers method in which graphite is added to cooled concentrated sulfuric acid containing sodium sulfate and stirred until homogeneous, and then potassium permanganate is added to oxidize, Alternatively, a chemical dispersion preparation method using a graphite raw material obtained by improving these methods is preferably used. Among these methods, the Hummers method or the improved Hummers method is particularly preferable because the reaction is the mildest and industrially easy to use.

  In these chemical preparation methods, a dispersion using an aqueous solvent can be obtained by removing unnecessary metal compounds, metal ions, acid ions, and the like from the obtained reaction solution by centrifugation or filtration. The extremely small aromatic carbon film in the aqueous dispersion contains functional groups derived from oxygen atoms, that is, hydroxyl groups (—OH), carboxyl groups (—COOH), esters (—COO—), ethers (—O—), and the like. It becomes easy to be dispersed in an aqueous solvent or an organic solvent. However, by having a functional group, characteristics such as conductivity and mobility inherently possessed by the aromatic carbon film tend to be lowered.

These ultrafine graphenes or exfoliated graphites having functional groups derived from oxygen atoms lose some oxygen atoms through a reduction treatment, even after they are laid down and laminated, or in the state of dispersion. The characteristics can be recovered to a state close to that of the original aromatic carbon film. Here, as the reduction treatment, chemical reduction with a reducing agent such as sodium borohydride (NaBH ₄ ) or hydrazine (N ₂ H ₄ ), reduction with a light source such as laser light, flash light, ultraviolet light, microwave, or electromagnetic wave, A wide variety of methods can be employed, such as heating and reducing to 100 ° C. or higher in an inert atmosphere. However, if the reduction process is performed in the state of a dispersion, the very finely dispersed graphene or exfoliated graphite may aggregate due to interaction. It is preferable to be performed.

  Among the various aromatic carbon films described above, the aromatic carbon film used in the present invention is composed of an aromatic carbon film produced by a thermal CVD method or a plasma CVD method, and a very small amount of graphene or exfoliated graphite. An aromatic carbon film laminated and laminated is more preferable, and in particular, an aromatic carbon film produced by a thermal CVD method or a plasma CVD method has a small number of graphene layers and a high-quality graphene structure with high conductivity. It is most preferable.

The thin film formed by ion plating in the method for producing a patterned aromatic carbon film of the present invention comprises at least one metal species. One kind of metal species may be used, or two or more kinds of metal species may be used in combination. Here, when two or more kinds of metal species are used in combination, for example, a lamination in which a thin film is formed using the first type of metal or metal compound and then the second or more type of metal or metal compound is formed from the top may be used. Alternatively, a plurality of types of metals or metal compounds may be present at the same time to form a thin film by ion plating, or a method of ion plating in the presence of a plurality of types of metals may be used in combination with the lamination. . And it is preferable to contain at most three kinds of metals. Among these, it is more preferable to use one kind of metal in that the process and time are reduced. Although it is preferable to use one kind of metal, the purity of the target used in ion plating may not be sufficiently high. Therefore, the metal component with a ratio of less than 0.1% is a metal formed into a thin film by ion plating. Not included in the number of species.
As a material used for forming a thin film by ion plating, as a metal, magnesium (Mg), aluminum (Al), calcium (Ca), scandium (Sc), vanadium (V), chromium (Cr), manganese ( Mn), iron (Fe), cobalt (Co), nickel (Ni), copper (Cu), zinc (Zn), gallium (Ga), arsenic (As), selenium (Se), strontium (Sr), yttrium ( Y), zirconium (Zr), niobium (Nb), molybdenum (Mo), ruthenium (Ru), rhodium (Rh), palladium (Pd), silver (Ag), cadmium (Cd), indium (In), tin ( Sn), antimony (Sb), tellurium (Te), barium (Ba), hafnium (Hf), tantalum (Ta), tungsten (W , Platinum (Pt), gold (Au), lead (Pb), and these metals may be used alone, or compounds of these metals, that is, oxides, nitrides, carbides, sulphides Further, it may be used as a metal compound such as fluoride, chloride, bromide or iodide, or may be used as a metal compound composed of a plurality of types of metals.

  Among these metal species, chromium, manganese, iron, nickel, copper, zinc, molybdenum, which are first transition elements, second transition elements, or third transition elements, are used in that ion plating is performed well. Silver, indium, tin, tungsten, platinum, gold, or oxides thereof are preferable, and iron, nickel, copper, zinc, indium, tin, which are first transition elements or second transition elements in terms of easy availability. Alternatively, these oxides are more preferable, and can be easily dissolved and removed in an acidic liquid at the time of forming a thin film, and the safety is relatively high, so that the first transition element iron, nickel, copper, zinc or these oxides are Particularly preferred. In addition, identification of the metal species and other compositions constituting these thin films is described in Example D. below. It is done by the method of the item.

  The thinner the thin film formed by the ion plating of the present invention, the shorter the formation time and the shorter the time for treatment with an acidic liquid. However, if the film is too thin, the aromatic carbon film as described later can be sufficiently removed. May be difficult. The thickness of the thin film is preferably 1 nm or more, more preferably 2 nm or more, and particularly preferably 5 nm or more. Moreover, 1 micrometer or less is preferable, 300 nm or less is more preferable, and 100 nm or less is especially preferable. The thickness of the thin film is the same as in Example B. below. It is confirmed by the method in the section.

  In the method for producing a patterned aromatic carbon film of the present invention, a thin film containing at least one metal species is formed by ion plating. As described above, as a method of forming a thin film containing at least one kind of metal species, a vacuum vapor deposition method and a sputtering method, which are physical thin film forming techniques, are conventionally known. The vacuum deposition method is a technique in which a solid that forms a thin film in a high vacuum is evaporated by resistance heating, electron beam, laser, high frequency induction, arc, etc., and the vapor is deposited on the substrate to form a thin film on the substrate. Is a relatively weak technique. Moreover, sputtering method puts inactive gas, such as argon gas, in a high vacuum, generates a plasma by applying a high voltage to the atmosphere and discharges it, and ionizes and accelerates the inert gas to form a thin film ( In some cases, the inert gas ions eject atoms or molecules constituting the target upon irradiation to the target, and the ejected atoms or molecules adhere to the substrate. This is a technique for forming a thin film with good adhesion as compared with a vapor deposition method.

  However, the present inventors have found that ion plating can be used very favorably for patterning of an aromatic carbon film as compared with these vacuum deposition methods and sputtering methods. The reason is considered as follows.

Ion plating is a method for forming a thin film with very good adhesion to a substrate, and the energy (eV) of particles when forming a thin film is higher than that of a sputtering method and is 10 to 100 times higher. In ion plating, as in the above-described vacuum deposition method, first, a solid for forming a thin film in a high vacuum is evaporated by resistance heating, electron beam, laser, high frequency induction, arc, or the like. At this time, the initial degree of vacuum is usually 10 ⁻³ Pa to 10 ⁻⁵ Pa. The evaporated particles themselves are ionized by applying a high voltage to form high energy particles, the evaporated particles are accelerated, and the evaporated particles collide with the substrate on which the thin film is placed at a high speed to form a thin film. Various conditions can be set for forming the thin film, but the most important is to set the conditions for ionizing the vaporized particles themselves to form high energy particles and further accelerating them to collide with the substrate at high speed. The pressure is preferably 0.0001 to 20.0 Pa, the ionization current is preferably 1 to 200 A, and the ionization voltage is preferably 10 to 300 V.

  The substrate here is an aromatic carbon film in the present invention, and as described above, a plurality of layers of constituting graphene are laminated. In this way, ion plating forms at least one kind of high energy particles. Since the thin film containing the metal species is formed, the structure of the aromatic carbon film in the portion where the thin film containing at least one metal species is formed is probably the above-mentioned, although the details are not yet well understood. It is considered that not only the graphene layer as in the sputtering method but also the graphene layer in contact with the substrate over a plurality of layers of graphene is damaged in the thickness direction. Therefore, when processing with an acidic liquid as will be described later, a plurality of layers of graphene reaching the graphene where the aromatic carbon film in the portion where the thin film containing at least one metal species is formed is in contact with the substrate is removed at once. It is thought that pattern processing is performed.

  In ion plating, although there are several methods for forming evaporated particles, it is possible to form a thin film containing at least one metal species by forming higher energy particles. Ion plating employing an evaporated particle forming method selected from a cathode electron beam method, a cluster ion beam method, and a multi-arc method is more preferable.

  The thin film containing at least one kind of metal in the method for producing an aromatic carbon film subjected to pattern processing of the present invention is treated with an acidic liquid. Any acidic liquid may be used as long as it can be processed by dissolving and removing the thin film containing at least one metal species formed by ion plating.

  Preferred acidic liquids here include inorganic acids such as hydrochloric acid, hydrobromic acid, hydroiodic acid, sulfuric acid, nitric acid and phosphoric acid, sulfonic acids such as methanesulfonic acid and paratoluenesulfonic acid, oxalic acid and formic acid, etc. Of these carboxylic acids, hydrochloric acid, sulfuric acid and nitric acid are particularly preferred because the thin film comprising at least one metal species described above is excellent in dissolution and removal in a short time.

  These acidic liquids are particularly preferably aqueous solutions, and the hydrogen ion index (pH) indicating the acidity of these acidic liquids is preferably as low as possible because the above-described thin film can be dissolved and removed in a short time. 2.0 or less, more preferably 1.5 or less.

  Further, the temperature of the acidic liquid at the time of treatment is preferable because the higher the temperature, the better the dissolution and removal. However, when the temperature is excessively high, the aromatic carbon film itself or the substrate on which the aromatic carbon film is mounted deteriorates. In some cases, the risk of an acidic liquid may increase, so it is preferably 5 ° C to 98 ° C, more preferably 10 ° C to 80 ° C, and particularly preferably 15 ° C to 70 ° C. preferable.

  The method for producing a patterned aromatic carbon film of the present invention includes pattern processing. The pattern processing is performed by treating the thin film containing at least one type of metal species formed by ion plating with an acidic liquid. When the thin film is formed by ion plating, a desired pattern is processed. A pattern with a thin film is drawn by holding the patterned mask on the surface of the aromatic carbon film and performing ion plating from above the mask. In addition, by treating with an acidic liquid, all unnecessary objects to be removed are washed away and both the patterned removal part and the non-patterned non-removal part do not leave unnecessary dust like the laser patterning described above. .

  The thin film pattern drawn here is a portion that is removed by the subsequent treatment with the acidic liquid, as described above. The thin film is removed by the acidic liquid, and the aromatic carbon film directly below the thin film is also removed. A pattern by the aromatic carbon film is drawn in a portion where all the film is removed and no thin film is formed. That is, the pattern accuracy depends on the accuracy of the mask. In the pattern processing, since the aromatic carbon film has high resistance to acidic liquid, the degradation or the like does not occur or hardly occurs. Therefore, the conductivity required for the application using the present invention does not change in performance.

  Although the aromatic carbon film of the present invention is patterned, the width of the pattern end faces of all the layers constituting the layer is formed to be 10 micrometers or less. This means that, for example, when an aromatic carbon film is composed of 10 layers and patterned, the width of the farthest part of the end face of each layer at the processed part end face is 10 micrometers or less. In the explanatory view of the processed end face of the aromatic carbon film shown in FIG. 1, the distance 5 between the layer 3 and the layer 4 showing the widest width of the processed end face in the aromatic carbon film 2 on the substrate 1 is 10 micrometers. It means that it is less than a meter. By making the width of the pattern end face 10 μm or less, the pattern accuracy in pattern processing is improved, which is advantageous when a dense pattern is drawn. The narrower the end face of the pattern, the better the pattern accuracy and the more precise the pattern can be drawn, which is more preferably 8 micrometers or less, particularly preferably 5 micrometers or less, and most preferably 3 micrometers or less. The width is the same as in Example E. below. It is confirmed by the method in the section.

  And since the aromatic carbon film formed by patterning according to the present invention is promising for applications utilizing conductivity described later, it preferably has high conductivity, and the surface resistivity as a conductivity index is low. More preferably, it is preferably 2000Ω / □ or less, more preferably 1000Ω / □ or less, particularly preferably 500Ω / □ or less, and most preferably 300Ω / □ or less. Here, the surface resistivity is the following Example C.I. It is measured by the method of item.

  The aromatic carbon film obtained by pattern processing according to the present invention is not a film-like material, that is, particles, rods, fibers, and the like, and the excellent transparency and conductivity intended by the present invention are impaired. You may carry | support in the range which is not. Examples of the particles that can be supported here include metal fine particles and carbon-based fine particles such as furnace black, ketjen black, and acetylene black. The metal fine particles and carbon-based fine particles are preferably as the particle diameter is small, preferably 1 μm or less, more preferably 500 nm or less, particularly preferably 100 nm or less, and most preferably 50 nm or less.

  In addition, single-walled carbon nanotubes (hereinafter, carbon nanotubes may be abbreviated as CNT), multi-walled CNTs having two or more layers, vapor-grown carbon fibers (hereinafter sometimes abbreviated as VGCF), cup-stacked CNTs, carbon Examples of the material that can also support a rod-like carbon material or a fibrous carbon material such as nanohorn, and the diameter of the rod-like carbon material or the fibrous carbon material is preferably 200 nm or less, more preferably 100 nm or less, and 50 nm. It is particularly preferred that The thinner the rod-like carbon material or the fibrous carbon material, the better the light transmittance. However, the diameter is preferably 1 nm or more and more preferably 2 nm or more in order to maintain the strength capable of maintaining the structure.

  In addition, the transparent conductive composite of the present invention is one in which an aromatic carbon film formed by pattern processing is supported at least in part, and the transparent conductive composite is transparent on, for example, the substrate a in FIG. By adopting a glass substrate or a transparent plastic substrate, it is possible to achieve both excellent optical transparency and conductivity. Among these, it is preferable to use a transparent plastic substrate.

  Here, when pattern processing is performed by treating the thin film formed by ion plating on the surface of the aromatic carbon film with an acidic liquid, the aromatic carbon film is placed on the transparent glass substrate or the transparent plastic substrate. It is preferable to carry out with the membrane supported. The transparent glass substrate or the transparent plastic substrate preferably has a high light transmittance, and the light transmittance is preferably 90% or more, and more preferably 92% or more. Further, the higher the light transmittance of the transparent conductive composite in which an aromatic carbon film is supported on a transparent glass substrate or a transparent plastic substrate, the better, but it is preferably 87% or more, and more preferably 89% or more. Is more preferable, and 91% or more is particularly preferable. Here, the light transmittance is measured by the following Example A.1. It is confirmed by the method in the section.

  EXAMPLES Hereinafter, although an Example demonstrates this invention concretely and in detail, this invention is not restrict | limited only to these Examples. In the examples, “parts” means “parts by weight” unless otherwise specified. The physical property values in the examples were measured by the following methods.

A. Measurement of light transmittance Using a UV-VIS-NIR SPECTROTOPOMETER with UV-VIS-NIR SPECTROTOPOMETER made by Shimadzu Corporation, visible light near-infrared spectrophotometer, the light transmittance at a wavelength of 550 nm was measured. I got it.

B. Method of measuring the thickness of the metal thin film formed by ion plating, the thickness of the aromatic carbon film, and the number of graphene layers constituting the aromatic carbon film The thin film sample formed by ion plating is at 80 ° C. in a nitrogen atmosphere. After drying, the aromatic carbon film was dried at 80 ° C. under a nitrogen atmosphere, and after supporting amorphous carbon as a surface protective layer, both were subjected to a focused ion beam method using an FEI Strata DB235 at an acceleration voltage of 30 kV. Using a transmission electron microscope H-9000UHR III manufactured by Hitachi High-Technologies Corporation with an acceleration voltage of 300 kV and an aromatic carbon film thickness of less than 25 nm, it is 4 million times, and 25 nm or more and less than 50 nm. If there are two million times, observe the thickness and measure the thickness. And the thickness of the thin film with an average value of the thickness. In addition, the total number of graphenes in the aromatic carbon film was confirmed by observing the above 4 million times, counting the number of layers, and setting the number of layers as an average value of three different points separated by 100 μm or more.

C. Method for Measuring Surface Resistivity Measurement was performed after holding a sample to be measured in the atmosphere at a temperature of 23 ° C. and a humidity of 55% for at least 1 hour in the atmosphere. Using a four-probe PSP probe with an electrode spacing of 1.5 mm and an electrode radius of 0.26 mm, the measurement was performed with Loresta GP (MCP-T610) manufactured by Mitsubishi Chemical Analytech Co., Ltd. And 10 different points of the same sample were measured, and the average value of 8 measurements excluding the highest value and the lowest value was taken as the surface resistivity of the sample.

D. Method for Analyzing Atomic Composition on Thin Film Formed by Ion Plating and Acid Liquid The sample to be analyzed was used after drying at 80 ° C. in a nitrogen atmosphere. Using a scanning electron microscope SU8020 manufactured by Hitachi High-Technologies Corporation with an energy dispersive X-ray detector (EDX) X-Max SILICON DRIVE X-RAY DETECTOR manufactured by HORIBA, Ltd. at an acceleration voltage of 1 kV and a magnification of 100 times While observing, the atomic number concentration of each element was calculated and obtained.

E. Method for analyzing width of end face of aromatic carbon film subjected to pattern processing, confirmation of unnecessary dust and method for analyzing pattern drawing width The sample to be analyzed was dried at 80 ° C. in a nitrogen atmosphere, and then subjected to analysis. Using SFT-3500 manufactured by Shimadzu Corporation, the width of the end face of the aromatic carbon film that has been patterned is mapped and observed with a difference in dielectric constant voltage in the KFM mode with an observation field of view of 15 μm × 15 μm. The average value was calculated by measuring the width at 10 locations and obtained as the width. The pattern drawing width is analyzed with a laser microscope attached to the nanosearch microscope, observed at a magnification of 20 times, calculated from a scale bar to obtain a width, and an average value is obtained from the widths of 10 points different by 1 mm or more. The pattern drawing width was calculated and obtained.

[Reference Example 1] (Aromatic carbon film production method from ultrafine exfoliated graphite dispersion)
While stirring ice-cooled 405 parts of 98% sulfuric acid, 10 parts of natural graphite having an average particle size of 80 μm, 5 parts of sodium nitrate having a purity of 99% or more are added, and 30 parts of potassium permanganate having a purity of 99.3% or more are further added. Was added little by little, followed by reaction at 20 ° C. for 4 hours. The reaction product was diluted with 460 parts of pure water while cooling with ice, and then vigorously stirred for 15 minutes. Further, the mixture was vigorously stirred for 30 minutes while diluted with 680 parts of pure water, and then 60 parts of hydrogen peroxide solution having a concentration of 30% was added. The reaction was stopped by vigorous stirring for 10 minutes after the addition.

  The obtained mixture was centrifuged with a centrifugal force equivalent to 2000 times gravity (2000 × g) using a high-speed cooling centrifuge 7780II manufactured by Kubota Corporation. After centrifuging, the supernatant is removed to obtain a sample, and then the same amount of pure water as that of the removed supernatant is added to the obtained sample, followed by centrifugation at a centrifugal force of 5000 × g for 20 minutes. In the same manner, the solid is obtained in the same manner, and then the pure minute water is repeatedly washed with pure water and centrifuged at 20000 × g until the pH becomes 3 or more. An aqueous dispersion containing 0.5% by weight was obtained.

  When producing an aromatic carbon film on a substrate using the aqueous dispersion, a hydrophilic quartz glass substrate having a thickness of 0.5 mm and a size of 2 cm × 2 cm, which is obtained by applying UV ozone treatment for 30 seconds in advance, is prepared. Then, using the spin coater (MS-A150) manufactured by Mikasa Co., Ltd. on the quartz glass substrate, the above exfoliated graphite aqueous dispersion was dropped once for 30 seconds while rotating the quartz glass substrate at a spin speed of 1500 rpm. Waiting was repeated 50 times, 100 times, and 150 times to obtain three types of aromatic carbon film samples supported on a quartz glass substrate. Thereafter, the sample was vacuum-dried at 100 ° C. for 24 hours, and the filter paper impregnated with hydrazine monohydrate and the quartz glass substrate carrying the aromatic carbon film were put together in a petri dish having an inner diameter of 116 mm and a height of 24 mm. The mixture was then treated at 90 ° C. for 15 minutes. Thereafter, the quartz glass substrate carrying the aromatic carbon film was taken out of the petri dish and dried by heating under vacuum at 250 ° C. for 24 hours to obtain a sample of the aromatic carbon film carried on the quartz glass substrate slightly blackened.

  The thickness, surface resistivity, and light transmittance including the glass substrate of the aromatic carbon film obtained by this method were 9.3 layers on average (thickness 3.53 nm, surface resistivity 489 Ω / □, light transmittance 79 %: 50 times coating, hereafter sample (a)), 17.9 layers (6.80 nm, 231 Ω / □, 59%; 100 times coating, hereafter sample (b)), 25.8 layers (9.80 nm, 136 Ω) / □, 46%; 150 times of application, hereinafter sample (c)).

[Reference Example 2] (Method for producing large area aromatic carbon film)
A rolled copper foil having a thickness of 33 μm is placed in a vacuum apparatus, and the degree of vacuum is set to 1.0 × 10 ⁻⁵ Pa, and then hydrogen (H ₂ ): argon (Ar) = 50: 10 standard flow rate (sccm, 25 ° C. ), Each gas was introduced at a total pressure of 10 Pa, and plasma was generated by irradiating a microwave of 2.455 GHz at 5 kW to treat the rolled copper foil for 20 minutes. Then, after stopping the microwave irradiation, the degree of vacuum was again set to 1.0 × 10 ⁻⁵ Pa, and then each gas was totaled with a composition of hydrogen: argon: methane (CH ₄ ) = 15: 30: 45 sccm (25 ° C.). Aromatic formed on 4 types of rolled copper foil by introducing plasma at a pressure of 5 Pa and irradiating 25 kW microwave of 2.455 GHz for 10 seconds, 30 seconds, 60 seconds and 120 seconds, respectively. A carbon film sample was obtained.

Thereafter, the microwave irradiation was stopped, the vacuum degree was set to 1.0 × 10 ⁻⁵ Pa, and after 30 minutes, the inside of the vacuum apparatus was returned to atmospheric pressure to form an aromatic carbon film formed on four types of rolled copper foils. A sample was removed. The aromatic carbon film sample formed on the rolled copper foil was cut into a size of 1.5 cm × 1.5 cm per rolled copper foil, and then 1.0 wt% polymethyl methacrylate (number average molecular weight 100,000, An aromatic formed on a rolled copper foil coated with PMMA, immediately after placing a tetrahydrofuran (hereinafter referred to as THF) solution containing PMMA), immediately after spinning for 1 minute at 1000 rpm with the above-mentioned spin coater. A carbon film sample was obtained. Then, the aromatic carbon film sample formed on the rolled copper foil coated with the PMMA is gently floated on 100 mL of a 20 wt% ferric chloride (FeCl ₃ ) aqueous solution, and the rolled copper foil is dissolved over 30 minutes. After that, the aqueous ferric chloride solution was replaced with pure water at a rate of 10 cm ³ / min so as not to shake the water surface, and became colorless water. The same quartz glass substrate or polyethylene terephthalate (hereinafter referred to as PET) film (thickness 125 μm, light transmittance 94%) as in Example 1 was inserted and the PMMA-coated aromatic carbon film sample was skimmed and dried at room temperature for 24 hours. Later, PMMA was washed with THF to obtain four types of aromatic carbon film samples supported on a quartz glass substrate or a PET film substrate.

  The thickness of the aromatic carbon film of each sample, the surface resistivity, and the light transmittance including the glass substrate or the PET film substrate are each 2.3 layers (thickness 0.77 nm, surface resistivity 451 Ω / □, Light transmittance 92% on glass substrate; microwave irradiation for 10 seconds (hereinafter sample (d)), 7.2 layer (2.45 nm, surface resistivity 296Ω / □, 83% on PET film substrate; 30 seconds Irradiation, hereafter sample (e)), 12.9 layer (4.32 nm, 232 Ω / □, 70% on glass substrate; irradiation for 60 seconds, hereafter sample (f)), 23.5 layer (7.87 nm, 117 Ω) / □, 52% on the glass substrate; irradiation for 120 seconds, and then the thickness of the sample (g)).

[Examples 1 to 3]
Using the samples (a), (d), and (g) obtained in Reference Examples 1 and 2, the ultimate pressure was set to 1.73 × 10 ⁻³ Pa, and then introduced gas, pressure, and flow rate: Argon (Ar) , 0.1 Pa, 15 sccm, ionization current: 110 A, ionization voltage: 90 V, thin film formation time: 60 seconds, target: copper (purity 99.99% or more), no sample heating A stainless steel (SUS; type 304) mask (thickness 300 μm) is placed on each sample, and the four corners are fixed with polyimide tape, and hollow cathode ion plating is performed. A “G” type copper thin film was formed on the surface of each sample. Table 1 shows the film thickness of the copper thin film.

  Each sample on which the copper thin film was formed was immersed in 0.1 M hydrochloric acid (pH = 1.0) at 40 ° C. for 30 seconds to obtain an aromatic carbon film from which the copper thin film was removed. The copper and aromatic carbon film is completely removed and no unnecessary dust remains. And E.E. It confirmed by the method of. Table 1 shows the line width of the letter “G” and the pattern end face width of the patterned aromatic carbon film. The conductivity (surface resistivity) and light transmittance of the non-removed part were not changed, and excellent transparent conductivity was maintained.

[Comparative Example 1]
In Example 2, instead of ion plating, using a magnetron RF sputtering apparatus, the ultimate pressure is 5.0 × 10 ⁻⁴ Pa, the introduced gas, the pressure is Ar, 0.67 Pa, 200 W, 60 seconds, A copper thin film in which the letter “G” was cut out by sputtering was formed in the same manner as in Example 2, and immersed in 0.1 M hydrochloric acid (pH = 1.0) at 40 ° C. for 30 seconds to remove the copper thin film. An aromatic carbon film was obtained. Although the copper and unnecessary dust were completely removed, the aromatic carbon film directly under the copper thin film was removed only for one layer, but it was not completely removed. And E.E. It confirmed by the method of. The line width and pattern end face of the processed “G” character could not be confirmed.

[Examples 4 to 7]
When ion plating was performed in the same manner as in Example 1 using the samples (b), (c), (e), and (f) obtained in Reference Examples 1 and 2, zinc (Example 4) was used. ), Nickel (purity 99.99% or more, Example 5), aluminum (purity 99.999% or more, Example 6) and indium (purity 99.99% or more, Example 7) as targets. A thin film having the thickness shown in FIG. 1 was formed, and a mask made of stainless steel (SUS; type 304) having a thickness of 0.5 mm (thickness of hollow letters) was used as a mask, and 0.1 M hydrochloric acid ( Example 4) A patterned aromatic carbon film was obtained in the same manner as in Example 1 except that 0.1M sulfuric acid (Example 5) and 0.1M nitric acid (Examples 6 and 7) were used. It was. D. that the thin film formed in all of Examples 4 to 7 and the aromatic carbon film immediately below the thin film were completely removed and that there was no unnecessary dust. And E.E. It confirmed by the method of. The conductivity (surface resistivity) and light transmittance of the non-removed part were not changed, and excellent transparent conductivity was maintained.

  As described above, the method for producing a patterned aromatic carbon film of the present invention and the patterned aromatic carbon film can be obtained without losing the excellent electrical conductivity and light transmittance of the aromatic carbon film. Pattern processing applicable to the area is possible, and the pattern accuracy is very high. Therefore, the transparent conductive composite having the patterned aromatic carbon film of the present invention supported on at least one part functions as an electrode when used as a transparent electrode of a touch panel, electronic paper, a solar cell, or an organic EL. Can be fully expressed and can exhibit excellent performance since it has high light transmittance.

  The aromatic carbon film obtained by patterning obtained by the production method of the present invention is capable of very precise patterning and is excellent in transparent conductivity. It can be suitably used for a touch panel, electronic paper, a solar cell, or an organic EL element that requires a transparent electrode.

1: Substrate on which an aromatic carbon film is supported 2: Each layer of the aromatic carbon film 3: Layer (layer 3) which is the rightmost (inner side) layer constituting the aromatic carbon film
4: Layer (layer 4) which is the leftmost (outside) layer constituting the aromatic carbon film
5: Distance between layer 3 and layer 4 indicating the widest width of the patterned edge

Claims (8)

  A pattern process comprising: patterning comprising forming a thin film comprising at least one metal species on the surface of an aromatic carbon film by ion plating and then treating the thin film with an acidic liquid. A method for producing an aromatic carbon film.   The method for producing a patterned aromatic carbon film according to claim 1, wherein the aromatic carbon film comprises a plurality of layers of graphene.   The method for producing a patterned aromatic carbon film according to claim 2, wherein the number of graphene layers is 2 to 30.   The method for producing an aromatic carbon film formed by pattern processing according to any one of claims 1 to 3, wherein the metal species is selected from at least one of the first transition element, the second transition element and the third transition element. .   The method for producing an aromatic carbon film obtained by pattern processing according to any one of claims 1 to 4, wherein the acidic liquid is selected from at least one of hydrochloric acid, sulfuric acid, and nitric acid.   The method for producing an aromatic carbon film obtained by patterning according to any one of claims 1 to 5, wherein the acidic liquid has a hydrogen ion index (pH) of 2.0 or less.   A pattern-processed aromatic carbon film characterized in that the pattern end faces of all layers constituting the aromatic carbon film have a width of 10 micrometers or less.   The transparent conductive composite which carry | supported at least one part the aromatic carbon film by which the pattern process of Claim 7 was carried out.

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