JP2008052912A - Liquid material for transparent conductive film formation, method for forming transparent conductive film, and method for manufacturing electrooptical device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an oxide corpuscle and a liquid material for transparent conductive film formation which enable the formation of a transparent conductive film having stable electric characteristics even under a low-temperature process, a method for forming a transparent conductive film having stable electric characteristics, and a method for manufacturing a highly reliable electrooptical device. <P>SOLUTION: The liquid material 14A includes a dispersion medium 13 containing conductive particulates 11 that exert translucency when transformed into an oxide, and Ag corpuscles 12. The method for forming the transparent conductive film includes a step of disposing the liquid material 14A on a board P, the liquid material 14A including the dispersion medium 13 containing the conductive particulates 11 that exert translucency when transformed into an oxide, and the Ag particulates 12; a step of subjecting the liquid material 14A on the board P to a heat treatment under a depressurizing or reducing atmosphere to form a solid made of the liquid material 14A; and a step of subjecting the solid to an oxygen-containing atmosphere to oxidize the solid. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a liquid material for forming a transparent conductive film, a method for forming a transparent conductive film, and a method for manufacturing an electro-optical device.

As an electrode of a display device such as a liquid crystal device, a transparent conductive film using a transparent conductive material such as ITO (indium tin oxide) is used. Such a transparent conductive film is generally formed using a sputtering method, but it is also considered to form a transparent conductive film using a liquid phase method capable of reducing the process temperature (for example, Patent Documents). 1-3).
JP 2005-166350 A JP 2005-183054 A JP 2006-028431 A

  After applying the liquid material described in each of the above patent documents on the substrate in a desired planar pattern, a transparent conductive film having a desired shape can be formed on the substrate by performing a heat treatment. However, in order to obtain stable characteristics in the formation of a conductive film using these liquid materials, it is necessary to perform a heat treatment at 500 ° C. or higher, and when the heat treatment temperature is 350 ° C. or lower, the resistance of the transparent conductive film is deteriorated over time. There is a problem that it is difficult to ensure device reliability. For example, in the method using the ITO fine particles described in Patent Document 1, the contact between the ITO fine particles in the obtained transparent conductive film is unstable, so that resistance is likely to increase. Further, in the method of forming a transparent conductive film by oxidizing metal particles described in Patent Document 2, although the contact point is stable, the resulting oxide conductor has poor crystallinity and the activity of the active species is low. A sufficient carrier concentration cannot be obtained. Furthermore, in the method using the pyrolysis material described in Patent Document 3, the generation of carbon residue due to the fact that the decomposition of the pyrolysis material does not proceed completely and the decrease in crystallinity of the conductive film can cause an increase in sheet resistance.

  The present invention has been made in view of the above-mentioned problems of the prior art, and an object thereof is to provide conductive fine particles and a liquid material capable of forming a transparent conductive film having stable electrical characteristics even in a low-temperature process. It is said. Another object of the present invention is to provide a method for forming a transparent conductive film having stable electrical characteristics and a method for manufacturing an electro-optical device having excellent reliability.

  The liquid material for forming a transparent conductive film of the present invention comprises conductive fine particles that exhibit translucency when converted into an oxide and metal fine particles made of Ag in a dispersion medium. .

  According to this, since the dispersion medium has conductive fine particles that exhibit translucency when converted into an oxide and metal fine particles made of Ag, the dispersion medium can be removed by heating. Among the aggregated particles, metal fine particles exist so as to fill the gaps between the conductive fine particles. As a result, conduction between the conductive fine particles not fused by heating can be obtained through the metal fine particles. In addition, by including metal fine particles made of Ag in the dispersion medium, deterioration of mobility of the conductive fine particles can be suppressed. Therefore, according to the liquid material for forming a transparent conductive film of the present invention, it is possible to form a transparent conductive film that can maintain low resistance and is excellent in reliability.

  It is also preferred that the conductive fine particles contain one or more elements selected from In, Zn, Al, F and Sn.

  That is, it is preferably made of a material that exhibits translucency when converted into an oxide.

  It is preferable that the dispersion medium contains conductive fine particles made of a light-transmitting oxide and metal fine particles made of Ag.

  According to this, since the dispersion medium has conductive fine particles made of a translucent oxide and metal fine particles made of Ag, the particles aggregated by removing the dispersion medium by heating. The metal fine particles exist so as to fill the gaps between the conductive fine particles. As a result, conduction between the conductive fine particles not fused by heating can be obtained through the metal fine particles. In addition, by including metal fine particles made of Ag in the dispersion medium, deterioration of mobility of the conductive fine particles can be suppressed. Therefore, according to the liquid material for forming a transparent conductive film of the present invention, it is possible to form a transparent conductive film that can maintain low resistance and is excellent in reliability.

  In the liquid material for forming a transparent conductive film of the present invention, the conductive fine particles are preferably made of an oxide containing one or more elements selected from In, Zn, Al, F, and Sn.

  That is, the conductive fine particles are preferably made of an oxide constituting the transparent conductive material.

  In the transparent conductive film-forming liquid material of the present invention, the metal fine particles are preferably mixed so that the content of the metal fine particles is 0.01 to 10 wt% with respect to the conductive fine particles.

  According to this, a transparent conductive film having low resistance and excellent conductivity can be formed without affecting the transmittance. The basis for the numerical limitation will be described in an embodiment described later.

  In the liquid material for forming a transparent conductive film of the present invention, it is preferable to mix so that the content of metal fine particles is 0.5 to 2 wt% with respect to the conductive fine particles.

  According to this, it is possible to form a transparent conductive film with low resistance and excellent conductivity without affecting the transmittance. The basis for this numerical limitation will also be described in an embodiment described later.

  The method for forming a transparent conductive film of the present invention is a liquid material for forming a transparent conductive film, comprising conductive fine particles that exhibit translucency when converted into an oxide and metal fine particles made of Ag in a dispersion medium. Placing the transparent conductive film-forming liquid material on the substrate in a reduced pressure or reducing atmosphere to form a solidified product of the transparent conductive film-forming liquid material; and And a step of oxidizing the solidified product by heat treatment in a contained atmosphere.

  According to this method, by conducting heat treatment, the conductive fine particles are oxidized to become a metal oxide, and the solidified product can be converted into a transparent conductive film. At this time, since the metal fine particles exist so as to fill the gap between the conductive fine particles, stable conduction between the adjacent conductive fine particles can be obtained through the metal fine particles. Moreover, since the crystallinity of the transparent conductive film is improved, the reliability is improved as the film strength and adhesion are improved.

  A step of disposing on the substrate a liquid material for forming a transparent conductive film containing conductive fine particles made of a light-transmitting oxide film and metal fine particles made of Ag in a dispersion medium, and forming a transparent conductive film on the substrate And heat-treating the liquid material for use in a reduced pressure or reducing atmosphere.

  According to this method, since the liquid material for forming a transparent conductive film containing conductive fine particles made of oxide is used, the solidified product can be converted into a transparent conductive film simply by evaporating the dispersion medium. At this time, since the metal fine particles exist so as to fill the gap between the conductive fine particles, stable conduction between the adjacent conductive fine particles can be obtained through the metal fine particles. Moreover, since the crystallinity of the transparent conductive film is improved, the reliability is improved as the film strength and adhesion are improved.

  In the method for forming a transparent conductive film of the present invention, it is preferable that the heating temperature in the plurality of heat treatments is 300 ° C. or less.

  According to this method, it is possible to form a stop transfer film having good conductivity and reliability on a resin substrate having poor heat resistance. The formation method of this invention can be used suitably for manufacture of a flexible device.

  An electro-optical device manufacturing method according to the present invention is a method for manufacturing an electro-optical device having a transparent conductive film on a substrate, the conductive fine particles exhibiting translucency when converted into an oxide, and Ag. A transparent conductive film-forming liquid material comprising a metal fine particle comprising a dispersion medium on a substrate, and the transparent conductive film-forming liquid material on the substrate is heat-treated in a reduced pressure or reducing atmosphere to be transparent A step of forming a solidified product of a liquid material for forming a conductive film, and a step of forming a transparent conductive film by oxidizing the solidified product by heat-treating the solidified product in an oxygen-containing atmosphere. .

  According to the present invention, an electro-optical device having a transparent conductive film having excellent conductivity and reliability can be easily manufactured, and an electro-optical device excellent in display characteristics and reliability can be provided. it can.

  The electro-optical device manufacturing method of the present invention is a method for manufacturing an electro-optical device having a transparent conductive film on a substrate, and includes conductive fine particles made of a light-transmitting oxide film, and metal fine particles made of Ag. A transparent conductive film-forming liquid material comprising a dispersion medium on the substrate, and the transparent conductive film-forming liquid material on the substrate is heat-treated in a reduced pressure or reducing atmosphere to form a transparent conductive film. And a process.

  According to the present invention, since it is not necessary to perform oxidation treatment, the number of work steps can be reduced, and the production can be efficiently performed in a short time.

<Liquid material for forming transparent conductive film>
Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a schematic cross-sectional view showing a state where a liquid material for forming a transparent conductive film (hereinafter simply referred to as a liquid material) containing conductive fine particles and Ag fine particles according to the present embodiment is applied on a substrate.

First, the liquid material 14A according to the present embodiment will be described. The liquid material 14A is used for forming a transparent conductive film. As shown in FIG. 1, the liquid material 14 </ b> A according to the present embodiment includes conductive fine particles 11 and Ag fine particles 12 (metal fine particles) made of a light-transmitting oxide film in a dispersion medium 13 by performing an oxidation treatment. Are dispersed.
(Conductive fine particles)
The conductive fine particles 11 can be used as long as they have electrical conductivity, and among them, those having high translucency by performing oxidation treatment are used. In the present embodiment, for example, an alloy containing one or more elements selected from In, Zn, Al, F, Sn, and the like can be given. Specifically, alloys such as In—Sn, Sn—Sb, F—Sn, Zn—Al, In—Zn, and Ga—Zn can be exemplified. The conductive fine particles 11 can be manufactured using a known fine particle manufacturing method regardless of a liquid phase method or a gas phase method. Specific examples include a gas evaporation method, a liquid phase reduction method, a spray method, and the like, and an appropriate method may be selected according to the material of the conductive fine particles 11.

The particle diameter of the conductive fine particles 11 is preferably about 1 nm to 100 nm, and more preferably in the range of 1 nm to 40 nm. By using a material having a particle diameter of 0.1 μm or less, clogging can be prevented from occurring when the liquid material 14A containing the conductive fine particles 11 is discharged from the droplet discharge head. Moreover, if it is set as the range of 1 nm-40 nm, favorable electroconductivity and transparency can be obtained about the transparent conductive film 14C formed using the electroconductive fine particles 11. Here, if the average particle diameter of the conductive fine particles 11 is too large, the gap (gap) between the conductive fine particles 11 becomes large in the obtained transparent conductive film 14C, and as a result, sufficient conductivity may not be obtained. There is.
(Ag fine particles)
The Ag fine particles 12 have high conductivity because Ag is the main material. Its shape is either spherical, rod-like or string-like. The spherical Ag fine particles 12 preferably have a particle size of about 1 nm to 40 nm. The Ag fine particles 12 having a rod shape or string shape preferably have a short direction length in the range of 1 nm to 40 nm. Further, it is more preferable that the Ag fine particles 12 have a smaller particle size (shape) than the conductive fine particles 11. In the case of the Ag fine particles 12 having a particle diameter smaller than that of the conductive fine particles 11, the Ag fine particles 12 can exist so as to embed a gap between the conductive fine particles 11. The rod-shaped Ag fine particles 12 and the string-shaped Ag fine particles should have a certain length so that they can come into contact with the plurality of conductive fine particles 11. For this reason, the conductivity between the conductive fine particles 11 can be reliably and effectively improved through the Ag fine particles 12. With respect to this point, for example, it is possible to use several to several tens of spherical Ag fine particles 12 that are aggregated in a chain to form a chain.

  Here, when the particle diameter of the Ag fine particles 12 is too small, the particles are likely to aggregate with each other, and the dispersibility may be reduced. On the other hand, if the particle size of the Ag fine particles 12 is too large, clogging may occur when discharging from the droplet discharge head. Therefore, the particle size is set with sufficient consideration of these matters.

  In addition, since the fine particles made of Ag are easily available, the cost can be reduced.

The surfaces of the conductive fine particles 11 and the Ag fine particles 12 may be coated with an organic substance for the purpose of preventing aggregation of the fine particles when the liquid material 14A is prepared by dispersing in the dispersion medium 13.
(Dispersion medium)
The dispersion medium 13 is not particularly limited as long as the conductive fine particles 11 are well dispersed and do not cause aggregation. For example, in addition to water, alcohols such as methanol, ethanol, propanol, butanol, n-heptane, n-octane, decane, dodecane, tetradecane, toluene, xylene, cymene, durene, indene, dipentene, tetrahydronaphthalene, decahydro Hydrocarbon compounds such as naphthalene and cyclohexylbenzene, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, ethylene glycol methyl ethyl ether, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol methyl ethyl ether, 1,2-dimethoxyethane, bis (2- Methoxyethyl) ether, ether compounds such as p-dioxane, propylene carbonate, γ- Butyrolactone, N- methyl-2-pyrrolidone, dimethylformamide, dimethyl sulfoxide, can be exemplified polar compounds such as cyclohexanone. Of these, water, alcohols, and hydrocarbons are preferred in view of dispersibility of the conductive fine particles 11 and Ag fine particles 12, stability of the dispersion medium 13, and ease of application to the droplet discharge method (inkjet method). Compounds and ether compounds are preferable, and more preferable dispersion medium 13 includes water and hydrocarbon compounds.

  The liquid material 14 </ b> A of the present embodiment is a liquid material for forming a transparent conductive film, and the above-described conductive fine particles 11 and Ag fine particles 12 are dispersed in the dispersion medium 13.

  FIG. 2 is a diagram showing the relationship between sheet resistance and transmittance with respect to the Ag addition rate in the liquid material. The left vertical axis in FIG. 2 is the sheet resistance [Ω / □], and the right vertical axis is the transmittance [%]. The horizontal axis represents the Ag addition rate [wt%].

  As shown in FIG. 2, the sheet resistance R of the transparent conductive film 14 </ b> C obtained from the liquid material 14 </ b> A decreases in proportion to the added amount of the Ag fine particles 12, but the transmittance T decreases accordingly. It can be seen that the degree of opacity increases as the added amount of the Ag fine particles 12 increases. Therefore, it is desirable to appropriately set the content of the Ag fine particles 12 in view of the balance between conductivity and transparency.

  In the present embodiment, the content of the Ag fine particles 12 contained in the dispersion medium 13 is preferably added in a ratio of 0.01 to 10 wt% with respect to the conductive fine particles 11. The present inventor has found that the effect of reducing the sheet resistance R starts to appear after the addition at a ratio of 0.01 wt% with respect to the conductive fine particles 11. However, it has been found that if the ratio of the Ag addition ratio to the conductive fine particles 11 exceeds 10 wt%, the transmittance is affected. Therefore, the present inventor has determined that the minimum transmittance at which the obtained transparent conductive film 14C is useful is 80%, and the ratio of the addition ratio of Ag to the conductive fine particles 11 is up to 10 wt%.

  According to FIG. 2, it is more preferable to use the liquid material 14A having an Ag content in the range of 0.5 to 2 wt%, and in this case, the transparent conductive film 14C having a sufficient transmittance T and a low resistance. Can be obtained.

  The conductive fine particles 11 contained in the dispersion medium 13 have a content that fulfills the desired function of the transparent conductive film 14C. Further, if the addition amount (mixing amount) of the conductive fine particles 11 and the Ag fine particles 12 is too small, the formed transparent conductive film 14C becomes thin and easily breaks, or sufficient conductivity as the conductive film. There is a possibility that it cannot be obtained. On the other hand, if the addition amount (mixing amount) of the conductive fine particles 11 and the Ag fine particles 12 is too large, the dispersibility of the particles in the dispersion medium 13 is lowered and it becomes difficult to apply on the substrate P, and the transparent conductive film 14C. There is a possibility that the film thickness of the film becomes thick. Therefore, the particle diameter and the mixing ratio of the conductive fine particles 11 and the Ag fine particles 12 when blended in the dispersion medium 13 are adjusted so that the film thickness of the transparent conductive film 14C after firing can be suppressed within a predetermined range. You may do it.

  The surface tension of the liquid material 14A is preferably in the range of 0.02 N / m to 0.07 N / m in view of the content of the conductive fine particles 11 and the Ag fine particles 12 under the above conditions. When the liquid material 14A is ejected by the ink jet method, if the surface tension is less than 0.02 N / m, the wettability of the ink composition with respect to the nozzle surface increases, and thus flight bending easily occurs, resulting in 0.07 N / m. If it exceeds the upper limit, the shape of the meniscus at the nozzle tip is unstable, and it becomes difficult to control the discharge amount and the discharge timing. In order to adjust the surface tension, it is preferable to add a small amount of a surface tension adjusting agent such as a fluorine-based, silicone-based, or nonionic-based material to the dispersion medium 13 as long as the contact angle with the substrate P is not significantly reduced. The nonionic surface tension modifier improves the wettability of the liquid to the substrate P, improves the leveling property of the film, and helps prevent the occurrence of fine irregularities on the film. The surface tension adjusting agent may contain an organic compound such as alcohol, ether, ester, and ketone, if necessary.

  The viscosity of the liquid material 14A is preferably 1 mPa · s to 50 mPa · s. When the liquid material 14A is ejected as droplets using the inkjet method, if the viscosity is less than 1 mPa · s, the nozzle periphery is easily contaminated by the outflow of the ink, and if the viscosity is greater than 50 mPa · s, the nozzle Not only does the frequency of clogging in the holes increase, making it difficult to smoothly discharge droplets, but also the amount of droplets discharged is reduced.

(Method for forming transparent conductive film)
Next, a method for forming the transparent conductive film 14C using the liquid material 14A containing the conductive fine particles 11 and the Ag fine particles 12 in the dispersion medium 13 will be described.

  FIG. 3A is a schematic process diagram showing a method for forming a transparent conductive film of the present embodiment, and FIG. 3B is a cross-sectional process diagram of the transparent conductive film corresponding to each process shown in FIG. .

  In the present embodiment, as an example of a method for forming a transparent conductive film, a method for forming a transparent conductive film 14C on a substrate P as shown in FIG.

  In the method for forming a transparent conductive film according to this embodiment, as shown in FIGS. 3A and 3B, a liquid material 14A containing conductive fine particles 11 and Ag fine particles 12 is applied on a substrate P. The first step S1 and the second step of forming the solidified material 14B of the liquid material 14A on the substrate P by drying and solidifying the liquid material 14A by applying heat treatment to the liquid material 14A applied on the substrate P. S2 and a third step S3 for converting the solidified material 14B into the transparent conductive film 14C by oxidizing the solidified material 14B on the substrate P.

As the substrate P shown in FIG. 3B, a flexible substrate such as plastic can be used in addition to a hard substrate such as glass, quartz, and ceramics. The liquid material 14A is made of a dispersion medium in which the above-described conductive fine particles 11 and Ag fine particles 12 are dispersed in a dispersion medium 13 such as an organic solvent.
[Liquid material application process]
In the first step S1, the liquid material 14A is applied on the substrate P. The application method of the liquid material 14A is not particularly limited, and various methods can be employed. For example, a liquid droplet discharge method, a CAP coating method, a die coating method, a curtain coating method, or the like can be used. It can be used according to the application form.

  When the transparent conductive film 14C having a specific planar shape is formed at a specific position on the substrate P, it is preferable to use a droplet discharge method. Here, FIG. 4A is a perspective view showing a schematic configuration of the droplet discharge device IJ used in the present embodiment.

  The droplet discharge device IJ includes a droplet discharge head 301, an X-axis direction drive shaft 304, a Y-axis direction guide shaft 305, a control device CONT, a stage 307, a cleaning mechanism 308, a base 309, and a heater. 315. The droplet discharge device IJ discharges droplets onto the substrate P while relatively scanning the droplet discharge head 301 and the stage 307 supporting the substrate P. Although the droplet discharge head 301 is disposed at a right angle to the traveling direction of the substrate P, the angle of the droplet discharging head 301 may be adjusted so as to intersect the traveling direction of the substrate P. In this way, the pitch between the nozzles can be adjusted by adjusting the angle of the droplet discharge head 301. Further, the distance between the substrate P and the nozzle surface may be arbitrarily adjusted.

  FIG. 4B is a schematic configuration diagram of a droplet discharge head for explaining the principle of discharging a liquid material by a piezo method. In the droplet discharge head 301, a piezo element 322 is disposed adjacent to a liquid chamber 321 that stores a liquid material (ink). The liquid material is supplied to the liquid chamber 321 via a liquid material supply system 323 including a material tank that stores the liquid material. The piezo element 322 is connected to a drive circuit 324, and a voltage is applied to the piezo element 322 via the drive circuit 324 to deform the piezo element 322 and elastically deform the liquid chamber 321. Then, the liquid material is discharged from the nozzle 325 by the change in the internal volume during the elastic deformation. In this case, the amount of distortion of the piezo element 322 can be controlled by changing the value of the applied voltage. In addition, the strain rate of the piezo element 322 can be controlled by changing the frequency of the applied voltage. Since the droplet discharge by the piezo method does not apply heat to the material, it has an advantage of hardly affecting the composition of the material.

When the droplet discharge method is used, a bank (weir) as a partition member for the liquid material 14A may be formed on the substrate P. The bank can be formed by an arbitrary method such as a lithography method or a printing method. By disposing the liquid material 14A in the region partitioned by the bank, the transparent conductive film 14C having a desired planar shape can be formed on the substrate P with an accurate position and shape.
[Heat treatment process]
As shown in FIG. 3B, when the liquid material 14A is discharged and arranged on the substrate P using the above-described droplet discharge device IJ, the dispersion medium 13 is removed from the liquid material 14A on the substrate P. In addition, the second step S2, which is a heat treatment step, is performed. The second step S2 is performed under a vacuum reduced pressure atmosphere, an inert atmosphere, or a reducing atmosphere. That is, the second step S2 is performed in an environment excluding oxygen. As such an environment, a vacuum decompression atmosphere of about 10 ⁻⁵ Pa to 10 ³ Pa, an inert atmosphere such as N ₂ gas, Ar gas (or other rare gas), or H ₂ gas, H ₂ gas A reducing atmosphere such as a mixed gas with an inert gas, CO gas, or a mixed gas of CO gas and CO ₂ gas can be exemplified.

  The treatment temperature of the second step S2 is the boiling point (vapor pressure) of the dispersion medium 13, the type and pressure of the atmospheric gas, the thermal behavior such as the dispersibility and oxidation of the fine particles, the presence and amount of the coating material, It may be determined in consideration of the heat resistant temperature. For example, in order to remove the coating material made of an organic material, it is necessary to perform baking at least at about 300 ° C. Moreover, when using a board | substrate with inferior heat resistance, such as a plastics, it is preferable to carry out at room temperature or more and 100 degrees C or less. The heating time is appropriately set according to the heating temperature.

  The conductive fine particles 11 and the Ag fine particles 12 can be arranged more orderly by appropriately setting the heating temperature and the heating time and adjusting the heating rate of the dispersion medium 13. Further, regarding this point, in order to further promote the densification of the conductive fine particles 11 and the Ag fine particles 12, it may be performed while applying vibration. Thereby, it can prevent that a bubble is contained inside.

  The second step S2 is performed for the purpose of removing the dispersion medium 13 contained in the liquid material 14A and promoting fusion between the conductive fine particles 11. By the heat treatment in the second step S2, as shown in FIGS. 3A and 3B, the dispersion medium 13 is removed, the conductive fine particles 11 and the Ag fine particles 12 are aggregated, and the particles contact each other. A solidified product 14B is formed on the substrate P. At this time, the Ag fine particles 12 aggregate while entering so as to fill the gaps between the conductive fine particles 11. Thus, by using a combination of two types of particles having different shapes (conductive fine particles 11 and Ag fine particles 12), it is possible to effectively increase the densification by eliminating gaps between the particles. In addition, when the surface of the conductive fine particles 11 is provided with an organic coating for preventing aggregation, this coating is also decomposed and removed in the second step S2.

  In the present embodiment, the conductive fine particles 11 are made of a metal film containing one or more elements selected from In, Zn, Al, F, and Sn, and contain a metal that melts at a relatively low temperature. Therefore, a part of the conductive fine particles 11 is melted even at a heating temperature of 300 ° C. or less, and the adjacent conductive fine particles 11 are fused.

  Further, the Ag fine particles 12 that exist so as to fill the gaps between the conductive fine particles 11 that are not fused remain in their initial shape because the melting temperature of Ag is 300 ° C. or higher. At this time, for example, the conductive fine particles 11 and the Ag fine particles 12 that have adhered are partially adhered to the Ag fine particles 12 by heating.

  As described above, in the second step S2, the conductive fine particles 11 and the Ag fine particles 12 are aggregated by performing the heat treatment on the liquid material 14A in a vacuum reduced pressure atmosphere, an inert atmosphere, or a reducing atmosphere. Adhesion between adjacent conductive fine particles 11 can be advanced. In addition, since the conductive fine particles 11 can be connected to each other via the Ag fine particles 12, a very stable contact can be formed between the particles. Thereby, the film density is increased and the crystallinity is improved, and as a result, an excellent low-resistance transparent conductive film 14C can be formed.

The second step S2 can be performed by, for example, an overall heat treatment using a hot plate, a constant temperature chamber or the like, or a local heat treatment by light irradiation using a flash lamp. In the case of using a flash lamp, the light irradiation conditions are such that the light irradiation energy is about 1 to 50 J / cm ² and the light irradiation time is about 1 μsec to several milliseconds, and the second step S2 is executed very quickly. be able to.
[Oxidation treatment process]
If the solidified material 14B is formed on the substrate P, the third step S3 for converting the solidified material 14B into the transparent conductive film 14C by oxidizing is then performed. The third step S3 is performed, for example, by selectively subjecting the solidified material 14B in an oxygen-containing atmosphere or by subjecting the whole including the substrate P to a heat treatment (for example, baking). The oxygen-containing atmosphere may be an atmospheric environment or a mixed gas atmosphere of oxygen gas and inert gas (N ₂ gas, rare gas, etc.).

  By heating the solidified material 14B in an oxygen-containing atmosphere in this manner, as shown in FIGS. 3A and 3B, the conductive fine particles 11 are oxidized to become a metal oxide, and the solidified material 14B is converted into a transparent conductive material. The film 14C can be converted. That is, by interposing the Ag fine particles 12 so as to fill the gaps between the conductive fine particles 11 that are not fixed, electrical connection between the conductive fine particles 11 is ensured and converted to the transparent conductive film 14C. The connection instability between the conductive fine particles 11 is eliminated, and the metal oxide has good crystallinity. Therefore, the transparent conductive film 14C becomes a conductive film having an excellent low resistance as a whole. Further, since the conductive fine particles 11 are connected to each other through the Ag fine particles 12, in the transparent conductive film 14C obtained by oxidizing the solidified product 14B, the contact between the particles is stable and the transparent having excellent reliability. The conductive film 14C is formed.

  On the other hand, if the heating temperature is too low, the conductive fine particles 11 may not be sufficiently fixed to each other via the Ag fine particles 12. On the other hand, even if the heating temperature is increased more than necessary, no further effect can be expected. Further, the heating time is appropriately set according to the heating temperature, and is a time for sufficiently proceeding with the oxidation of the solidified product 14B.

  As described above, according to the method for forming the transparent conductive film 14 </ b> C of the present embodiment, the following special effects that cannot be obtained by the conventional technique can be obtained. First, in a transparent conductive film formed by applying a liquid material containing conventional ITO fine particles onto a substrate P, drying and baking the same, the contacts between the ITO fine particles constituting the transparent conductive film are unstable, and over time There was a problem that the resistance value changed. Moreover, in the transparent conductive film formed by oxidizing the conventional metal fine particles, although the contact point is stable, the crystallinity of the formed transparent conductive film is poor and the resistance tends to increase. In contrast, in the present embodiment, the Ag fine particles 12 exist so as to fill the gaps between the conductive fine particles 11 that are not fused. Thereby, the connection between the electroconductive fine particles 11 can be stabilized, and the transparent conductive film 14C excellent in low resistance can be formed.

  Further, by melting, the contact area between the particles in the conductive fine particles 11 or the contact area between the particles in the Ag fine particles 12 and the conductive fine particles 11 increases, and a more stable connection is obtained. As a result, in the transparent conductive film 14C obtained by oxidizing the solidified material 14B, a highly reliable transparent conductive film 14C having excellent conductivity, film strength, and stable adhesion to the substrate P can be obtained.

[Other Embodiments of Liquid Material for Forming Transparent Conductive Film]
First, the liquid material 14A according to the present embodiment will be described. As shown in FIG. 5, the liquid material 14 </ b> A according to the present embodiment is formed by dispersing conductive fine particles 11 ′ having translucency and Ag fine particles 12 (metal fine particles) in a dispersion medium 13. In the present embodiment, portions corresponding to the respective portions of the first embodiment are denoted by the same reference numerals, and description thereof is omitted.
(Conductive fine particles)
The conductive fine particles 11 ′ of the present embodiment can be used as long as they are made of an inorganic oxide and have electrical conductivity. Among them, those having particularly high translucency are used. For example, an oxide containing one or more elements selected from In, Zn, Al, F, Sn, and the like can be given. Specifically, ITO (In—Sn—O), ATO (Sn—Sb—O), FTO (F—Sn—O), AZO (Zn—Al—O), IZO (In—Zn—O), Examples thereof include complex oxides such as GZO (Ga—Zn—O), and inorganic oxides such as In 2 O 3, ZnO, and SnO 2. The conductive fine particles 11 ′ can be manufactured using a known fine particle manufacturing method regardless of a liquid phase method or a gas phase method. Specific examples include a gas evaporation method, a liquid phase reduction method, and a spray method, and an appropriate method may be selected according to the material of the conductive fine particles 11 ′.

  In addition, the conductive fine particles 11 in which the crystallinity of the oxides constituting the fine particles is improved are produced by subjecting the fine particles formed by the vapor phase method or the liquid phase method to a heat treatment of about 500 ° C. to 800 ° C. It is preferable to do. In this way, by increasing the crystallinity of the oxide constituting the conductive fine particles 11, when the transparent conductive film 14C is formed using the conductive fine particles 11, the transparent conductive film having good crystallinity. 14C. Therefore, it is possible to obtain a transparent conductive film 14C having low resistance and excellent reliability.

(Method for forming transparent conductive film)
Next, a method of forming the transparent conductive film 14C using the liquid material 14A containing the conductive fine particles 11 ′ made of oxide and the Ag fine particles 12 in the dispersion medium 13 will be described.

  FIG. 5A is a schematic process diagram showing a method for forming a transparent conductive film of the present embodiment, and FIG. 5B is a cross-sectional process diagram of the transparent conductive film corresponding to each process shown in FIG. .

  In this embodiment, as an example of a method for forming a transparent conductive film, a method for forming a transparent conductive film 14C on a substrate P as shown in FIG. 5B will be described.

In the method of forming the transparent conductive film 14C of the present embodiment, as shown in FIGS. 5A and 5B, a liquid material 14A containing conductive fine particles 11 ′ and Ag fine particles 12 is applied on a substrate P. The first step S1 and the second step of forming the transparent conductive film 14C made of the liquid material 14A on the substrate P by drying and solidifying the liquid material 14A by subjecting the liquid material 14A applied on the substrate P to heat treatment. Step S2.
[Liquid material application process]
In the first step S1, the liquid material 14A is applied on the substrate P. The application method of the liquid material 14A is not particularly limited, and various methods can be employed. For example, a liquid droplet discharge method, a CAP coating method, a die coating method, a curtain coating method, or the like can be used. It can be used according to the application form.

When the transparent conductive film 14C having a specific planar shape is formed at a specific position on the substrate P, a droplet discharge device IJ shown in FIG. 4 is used.
[Heat treatment process]
As shown in FIG. 5B, when the liquid material 14A is discharged and arranged on the substrate P using the above-described droplet discharge device IJ, the dispersion medium 13 is removed from the liquid material 14A on the substrate P. In addition, the second step S2, which is a heat treatment step, is performed. The second step S2 is performed under a vacuum reduced pressure atmosphere, an inert atmosphere, or a reducing atmosphere. That is, the second step S2 is performed in an environment excluding oxygen. As such an environment, a vacuum decompression atmosphere of about 10 ⁻⁵ Pa to 10 ³ Pa, an inert atmosphere such as N ₂ gas, Ar gas (or other rare gas), or H ₂ gas, H ₂ gas A reducing atmosphere such as a mixed gas with an inert gas, CO gas, or a mixed gas of CO gas and CO ₂ gas can be exemplified.

  The treatment temperature of the second step S2 is the boiling point (vapor pressure) of the dispersion medium 13, the type and pressure of the atmospheric gas, the thermal behavior such as the dispersibility and oxidation of the fine particles, the presence and amount of the coating material, It may be determined in consideration of the heat resistant temperature. For example, in order to remove the coating material made of an organic material, it is necessary to perform baking at least at about 300 ° C. Moreover, when using a board | substrate with inferior heat resistance, such as a plastics, it is preferable to carry out at room temperature or more and 100 degrees C or less. The heating time is appropriately set according to the heating temperature.

  The conductive fine particles 11 ′ and the Ag fine particles 12 can be arranged more orderly by appropriately setting the heating temperature and the heating time and adjusting the heating rate of the dispersion medium 13. Further, regarding this point, the conductive fine particles 11 ′ and the Ag fine particles 12 may be subjected to vibration in order to further promote densification. Thereby, it can prevent that a bubble is contained inside.

  The second step S2 is performed for the purpose of removing the dispersion medium 13 contained in the liquid material 14A and promoting fusion between the conductive fine particles 11 '. By the heat treatment in the second step S2, as shown in FIGS. 5A and 5B, the dispersion medium 13 is removed, the conductive fine particles 11 ′ and the Ag fine particles 12 are aggregated, and the particles are mutually bonded. The solidified material 14B that comes into contact is formed on the substrate P. At this time, the Ag fine particles 12 aggregate while entering to fill the gaps between the conductive fine particles 11 ′. Thus, by using a combination of two types of particles having different shapes (conductive fine particles 11 ′ and Ag fine particles 12), it is possible to effectively increase the densification by eliminating gaps between the particles. In addition, when the surface of the conductive fine particles 11 ′ is provided with an organic coating for preventing aggregation, this coating is also decomposed and removed in the second step S <b> 2.

  In the present embodiment, the conductive fine particles 11 ′ are made of a metal film containing one or more elements selected from In, Zn, Al, F, and Sn, and contain a metal that melts at a relatively low temperature. . Therefore, part of the conductive fine particles 11 ′ is melted even at a heating temperature of 300 ° C. or less, and adjacent conductive fine particles 11 ′ are fused.

  Further, the Ag fine particles 12 that exist so as to fill the gaps between the conductive fine particles 11 ′ that are not fused remain in the initial shape because the melting temperature of Ag is 300 ° C. or higher. At this time, for example, the conductive fine particles 11 ′ and the Ag fine particles 12 that have adhered are partially adhered to the Ag fine particles 12 by heating.

  As described above, in the second step S2, the conductive fine particles 11 ′ and the Ag fine particles 12 are aggregated by performing heat treatment on the liquid material 14A in a vacuum reduced pressure atmosphere, an inert atmosphere, or a reducing atmosphere. Adhesion between the adjacent conductive fine particles 11 ′ can be advanced. In addition, since the conductive fine particles 11 ′ can be connected to each other through the Ag fine particles 12, a very stable contact can be formed between the particles. Thereby, the film density is increased and the crystallinity is improved, and as a result, an excellent low-resistance transparent conductive film 14C can be formed.

In the present embodiment, since the conductive fine particles 11 ′ made of an oxide are used, the transparent conductive film 14 </ b> C is formed only by evaporating the dispersion medium 13. Since there is no need for an oxidation treatment step as in the first embodiment, it is possible to improve production efficiency and reduce costs associated with a reduction in the number of work steps.
<Electro-optical device and manufacturing method thereof>
The transparent conductive film 14C according to the previous embodiment can be suitably used as an electrode or an electrostatic protection film of various electro-optical devices. Hereinafter, a configuration of a liquid crystal display device which is an example of an electro-optical device according to the present invention and an example of a manufacturing method thereof will be described with reference to the drawings.

  The liquid crystal display device according to the present embodiment applies an electric field to a liquid crystal having a negative dielectric anisotropy that is aligned perpendicular to the substrate surface, and controls the alignment to perform image display by VAN (Vertical Aligned). Nematic mode active matrix liquid crystal display device, which is a transmissive liquid crystal display device that performs display using light supplied from a backlight disposed on the back side of the panel.

  The liquid crystal display device of the present embodiment can perform color display using a color filter provided on the substrate, and outputs three color lights of R (red), G (green), and B (blue). One pixel is composed of sub-pixels.

  Therefore, in this specification, a display area that is a minimum unit constituting a display is referred to as a “sub-pixel”. A display area composed of a set (R, G, B) of sub-pixels is referred to as a “pixel”.

  In the drawings referred to in each embodiment, each layer and each member are displayed in different scales so that each layer and each member have a size that can be recognized on the drawing.

  FIG. 5 is a circuit configuration diagram of a plurality of sub-pixels formed in a matrix that constitutes the liquid crystal display device of the present embodiment. FIG. 7 is an overall configuration diagram of the liquid crystal display device 100. FIG. 8 is a diagram showing a planar configuration of a TFT array substrate in a pixel composed of three subpixels. FIG. 9 is a partial cross-sectional configuration diagram of the liquid crystal display device 100 taken along the line BB ′ of FIG.

  As shown in FIG. 6, the image display area of the liquid crystal display device 100 has a plurality of sub-pixels Sp arranged in a matrix. Each sub-pixel Sp is formed in a rectangular region partitioned by a plurality of scanning lines 18 a extending in a direction intersecting each other and a plurality of data lines 16. In the sub-pixel Sp, a pixel electrode 19 and a TFT (thin film transistor) 60 for controlling the switching of the pixel electrode 19 are formed. The data line 16 is electrically connected to the source of the TFT 60, and image signals S1, S2,..., Sn supplied from a drive circuit (not shown) are written to each sub-pixel via the data line 16. ing. The image signals S1 to Sn may be supplied line-sequentially in this order, or may be supplied for each group to a plurality of adjacent data lines 16.

  A scanning line 18a is electrically connected to the gate of the TFT 60, and scanning signals G1, G2,..., Gm supplied in a pulsed manner to the scanning line 18a at a predetermined timing from a drive circuit (not shown) are arranged in this order. It is applied to the gate of the TFT 60 in a line sequential manner. The pixel electrode 19 is electrically connected to the drain of the TFT 60. The TFT 60 serving as a switching element is turned on for a predetermined period by the input of the scanning signals G1, G2,..., Gm, so that the image signals S1, S2,. Writing is performed on the pixel electrode 19.

  Image signals S1, S2,..., Sn written to the liquid crystal through the pixel electrode 19 are held for a certain period between the pixel electrode 19 and the common electrode facing through the liquid crystal. Here, in order to prevent the held image signal from leaking, the storage capacitor 17 is connected in parallel with the liquid crystal capacitor formed between the pixel electrode 19 and the common electrode. The storage capacitor 17 is provided between the drain of the TFT 60 and the capacitor line 18b.

  As shown in FIG. 7, in the liquid crystal display device 100 of this embodiment, a TFT array substrate (first substrate) 10 and a counter substrate (second substrate) 20 are bonded together by a sealing material 52, and the partitioning is performed by the sealing material 52. In this configuration, the liquid crystal layer 50 is sealed in the region. A rectangular area surrounded by a peripheral parting line 53 provided along the inner periphery of the sealing material 52 is an image display area. In the peripheral circuit area outside the sealing material 52, the data line driving circuit 101 and the external circuit mounting terminal 102 are formed along one side of the TFT array substrate 10, and the scanning line is formed along two sides adjacent to the one side. Each of the drive circuits 104 is formed. The scanning line driving circuits 104 are electrically connected to each other via a wiring 105, and the data line driving circuit 101 and the scanning line driving circuits 104 and 104 are electrically connected to the corresponding external circuit mounting terminals 102, respectively. It is connected. In addition, an inter-substrate conductive material 106 for providing electrical continuity between the TFT array substrate 10 and the counter substrate 20 is disposed at a corner portion of the counter substrate 20.

  Next, a detailed configuration of the liquid crystal display device 100 will be described with reference to FIGS.

  As shown in FIG. 9, the liquid crystal display device 100 includes a TFT array substrate (first substrate) 10 and a counter substrate (second substrate) 20 that are opposed to each other with the liquid crystal layer 50 interposed therebetween. A backlight (illumination device) 90 including a light guide plate 91 and a reflection plate 92 is disposed on the back side (the lower side in the drawing) of the TFT array substrate 10.

  As shown in the plan view of FIG. 8, the sub-pixel of the liquid crystal display device 100 is provided with a pixel electrode 19 and a TFT 60 which is a pixel switching element. A plurality of scanning lines 18a extending along the longitudinal direction (Y-axis direction) of the pixel electrode 19 and data lines 16 extending along the short direction (X-axis direction) of the pixel electrode 19 are formed. The line 16 and the scanning line 18a are electrically connected to the TFT 60 in the vicinity of the intersection.

  Further, one color filter (color material layer) 22 (22R, 22G, 22B) of the three primary colors is formed corresponding to one sub-pixel, and is arranged adjacent to each other including the three color filters 22. The three subpixels formed form one pixel. For example, the color filter 22 is formed in a stripe shape extending in the vertical direction in the drawing for each color, and is formed across the plurality of sub-pixels in the extending direction, and is periodically arranged in the horizontal direction in the drawing. It has become a thing.

  The pixel electrode 19 is a transparent conductive film formed by the transparent conductive film forming method according to the present invention using a transparent conductive material such as ITO (indium tin oxide). Since the liquid crystal display device 100 of the present embodiment is a vertical alignment mode liquid crystal display device, the subpixel region is divided into a plurality of island-shaped regions in addition to a method of imparting a pretilt to the liquid crystal by rubbing the alignment film. A so-called CPA (Continuous Pinwheel Alignment) structure in which a protrusion is provided at a position on the counter substrate corresponding to the center of the island-like region, or an MVA (Multi-alignment) that aligns liquid crystals in four directions based on a nucleus formed by the protrusion or slit structure A known alignment control structure such as a domain vertical alignment) structure can be employed.

  A TFT 60 is interposed between a cutout portion formed on the lower left side of the pixel electrode 19 shown in FIG. 8 and the scanning line 18 a and the data line 16. The TFT 60 includes a semiconductor layer 33, a gate electrode 32 provided on the lower layer side (substrate body 10 </ b> A side) of the semiconductor layer 33, a source electrode 34 provided on the upper layer side of the semiconductor layer 33, and a drain electrode 35. ing. In the present embodiment, the drain electrode 35 is formed of a strip-like conductive film having a width equivalent to that of the source electrode 34. However, the drain electrode 35 is further extended so as to overlap with the extended drain electrode in a plane. By arranging a capacitor line (or a capacitor electrode connected to the capacitor line), a storage capacitor of the subpixel can be formed.

  The gate electrode 32 is formed by branching a part of the scanning line 18a in the extending direction of the data line 16, and is opposed to the semiconductor layer 33 via an insulating film (not shown) on the tip side. The source electrode 34 is formed by branching a part of the data line 16 in the extending direction of the scanning line 18 a, and is electrically connected to the semiconductor layer 33 at a position overlapping with the plane. The drain electrode 35 and the semiconductor layer 33 are also electrically connected at a position where they overlap in a plane. The drain electrode 35 and the pixel electrode 19 are electrically connected via a pixel contact hole provided at the end of the drain electrode 35 opposite to the semiconductor layer 33.

  With such a configuration, the TFT 60 is turned on for a predetermined period by a gate signal input via the scanning line 18a, so that an image signal supplied via the data line 16 is output at a predetermined timing. It is possible to write on the LCD.

  On the other hand, looking at the cross-sectional structure shown in FIG. 9, the liquid crystal display device 100 includes a TFT array substrate 10 and a counter substrate 20 disposed to face the TFT array substrate 10, and is sandwiched between the substrates 10 and 20. The liquid crystal layer 50 is made of a liquid crystal having an initial alignment state of vertical alignment and negative dielectric anisotropy (refractive index anisotropy Δn is 0.1, for example).

  The TFT array substrate 10 has a substrate body 10A made of a translucent material such as quartz or glass as a base, and a gate electrode 32 (scanning line 18a) is formed on the inner surface side (liquid crystal layer side) of the substrate body 10A. . An insulating thin film (gate insulating film) 36 is formed so as to cover the gate electrode 32, and a semiconductor layer 33 made of an island-shaped amorphous silicon film or the like is formed on the insulating thin film 36 at a position facing the gate electrode 32. ing. A source electrode 34 and a drain electrode 35 are formed on the insulating thin film 36 so as to partially run over the semiconductor layer 33. Between the source electrode 34 and the semiconductor layer 33 and between the drain electrode 35 and the semiconductor layer 33, an n + silicon layer 33n that ohmic-joins the semiconductor layer 33 and the electrode is interposed.

  A first interlayer insulating film 37 is formed so as to cover the source electrode 34 and the drain electrode 35, and a second interlayer insulating film 38 is formed so as to cover the first interlayer insulating film 37. The first interlayer insulating film 37 is an insulating film made of a silicon nitride film or the like that protects each conductive film constituting the TFT 60, and the second interlayer insulating film 38 planarizes the surface of the substrate body 10A on which the TFT 60 or the like is formed. It is an insulating film made of a translucent resin material having a function. A pixel electrode 19 made of a transparent conductive film such as ITO is formed on the second interlayer insulating film 38. A part of the pixel electrode 19 is formed in the contact hole 45 that penetrates the first interlayer insulating film 37 and the second interlayer insulating film 38 and reaches the drain electrode 35. With this structure, the pixel electrode 19 and the drain electrode are formed. 35 is electrically connected. A vertical alignment film 39 made of polyimide or the like is formed so as to cover the pixel electrode 19, and liquid crystal molecules are aligned perpendicular to the substrate surface. A phase difference plate 46 and a polarizing plate 44 are laminated on the outer surface side of the substrate body 10A.

  The counter substrate 20 has a substrate body 20A made of a translucent material such as quartz or glass as a base. A color filter 22 is provided on the inner surface side of the substrate body 20A. As described above, the color filter 22 has a stripe shape extending in the longitudinal direction of the sub-pixels, and a boundary region between adjacent sub-pixels in the extending direction of each color filter 22 is made of a metal film, a black resin, or the like. A light shielding film (black matrix) 23 is disposed.

  A counter electrode 21 is formed on the color filter 22. The counter electrode 21 is a transparent conductive film made of flat solid ITO or the like, and the counter electrode 21 is also a transparent conductive film formed by the method for forming a transparent conductive film according to the present invention. A vertical alignment film 28 made of polyimide or the like is formed so as to cover the counter electrode 21, and liquid crystal molecules are aligned perpendicular to the substrate surface.

  A phase difference plate 26 and a polarizing plate 24 are laminated on the outer surface side of the substrate body 20A. The polarizing plates 44 and 24 have a function of transmitting only linearly polarized light that vibrates in a specific direction. The retardation plates 46 and 26 are λ / 4 plates having a phase difference of approximately ¼ wavelength with respect to the wavelength of visible light. The transmission axis of the polarizing plates 44 and 24 and the slow axis of the retardation plates 46 and 26 are arranged at an angle of about 45 °, and the polarizing plate 44 and the retardation plate 46, and the polarizing plate 24 and the retardation plate are arranged. 26 and cooperate with each other to function as a circularly polarizing plate. With this circularly polarizing plate, linearly polarized light is converted into circularly polarized light and made incident on the liquid crystal layer 50, while circularly polarized light emitted from the liquid crystal layer 50 is converted into linearly polarized light and output. Further, the transmission axis of the polarizing plate 44 and the transmission axis of the polarizing plate 24 are disposed orthogonally, and the slow axis of the retardation film 46 is disposed orthogonally to the slow axis of the retardation film 26.

  As a configuration of the polarizing plate and the retardation plate, a “polarizing plate + λ / 4 plate configuration circular polarizing plate” is common, but a “polarizing plate + λ / 2 plate + λ / 4 plate configuration circular polarizing plate ( By using “broadband circularly polarizing plate”, the black display can be made more achromatic.

  As described above, the pixel electrode 19 and the counter electrode 21 are formed by the method for forming a transparent conductive film according to the present invention. Hereinafter, a method for manufacturing the liquid crystal display device 100 will be briefly described.

  In order to manufacture the TFT array substrate 10, first, the TFT 60 and the first interlayer insulating film 37 and the second interlayer insulating film 38 covering the TFT 60 are formed on the substrate body 10 </ b> A by using a known manufacturing method. A pixel contact hole 45 penetrating the insulating film 37 and the second interlayer insulating film 38 is opened. Thereafter, the liquid material 14A including the conductive fine particles 11 and the Ag fine particles 12 according to the present invention is selectively disposed on the second interlayer insulating film 38 by using a droplet discharge method. At this time, if the bank is formed so as to surround the region where the pixel electrode 19 on the second interlayer insulating film 38 is to be formed, the liquid material 14A can be discharged and arranged more accurately.

  Next, the substrate body 10A is held under reduced pressure or a reducing atmosphere, and the liquid material 14A is heated to dry and solidify it to obtain a solidified product 14B. By heating this in an oxygen atmosphere, the solidified product 14B is heated. The pixel electrode 19 can be formed by converting into the transparent conductive film 14C. Thereafter, if an alignment film 39 made of a polyimide film is formed on the pixel electrode 19 by a spin coating method or the like, the TFT array substrate 10 can be manufactured.

  In this way, by applying the transparent conductive film forming method according to the present invention to the pixel electrode 19, the pixel electrode forming process, which has been conventionally formed by sputtering or the like and patterned using a photolithography technique, is performed. It can be performed by the phase method. As a result, the manufacturing of the pixel electrode 19 does not require a high temperature, and the waste of raw materials can be reduced, so that the deterioration of the substrate body 10A and the second interlayer insulating film 38 due to heating can be prevented, and the TFT array can be manufactured at low cost and high yield. The substrate 10 can be manufactured. In addition, since the pixel electrode 19 is formed by using the liquid phase method, it is caused by the film around the pixel contact hole 45 as in the case of forming the pixel electrode 19 by using a vapor phase method such as sputtering. Therefore, the TFT array substrate 10 is excellent in electrical reliability.

  Next, in order to manufacture the counter substrate 20, the light shielding film 23 and the color filter 22 are formed on the substrate body 20A by using a known manufacturing method such as a printing method or a droplet discharge method. Next, the liquid material 14A including the conductive fine particles 11 and the Ag fine particles 12 according to the present invention is disposed on the color filter 22 by using a spin coating method or a droplet discharge method. Next, the substrate body 20A is held under reduced pressure or in a reducing atmosphere, and the liquid material 14A is heated to dry and solidify it to obtain a solidified product 14B. By heating this in an oxygen atmosphere, the solidified product 14B is heated. The counter electrode 21 can be formed by converting to a transparent conductive film 14C. Then, if the alignment film 28 made of a polyimide film is formed on the counter electrode 21 by a spin coating method or the like, the counter substrate 20 can be manufactured.

  Since the counter electrode 21 is a flat solid transparent conductive film as described above, it is not necessary to use the droplet discharge method when applying the liquid material 14A on the color filter 22, and spin coating method or the like is used. It may be used as a whole and applied.

  Thus, when forming the counter electrode 21 on the color filter 22, by applying the method for forming the transparent conductive film of the present invention, the counter electrode having sufficiently low resistance and excellent reliability by heating at 300 ° C. or less. The electrode 21 can be formed. Therefore, the deterioration of the color filter 22 can be prevented by heating, and the counter substrate 20 can be manufactured at a low cost and a high yield.

  If the TFT array substrate 10 and the counter substrate 20 are manufactured through the above steps, the two are bonded together via the sealing material 52 and liquid crystal is injected into the inside through a sealing port provided in the sealing material 52, and then the sealing material. The liquid crystal display device 100 of the said embodiment can be manufactured by sealing 52 sealing openings with a sealing material.

Thus, in the liquid crystal display device 100 of the present embodiment, the transparent conductive film formed by the method according to the present invention for the pixel electrode 19 provided in each sub-pixel and the counter electrode 21 provided on the color filter 22. Therefore, the transparent conductive material is excellent in crystallinity, has stable contact between particles, and has a transparent electrode having excellent reliability and conductivity. Therefore, according to the present invention, a liquid crystal display device with low power consumption and excellent reliability can be provided. Further, since the droplet discharge method is used in the formation process of the pixel electrode 19, the electrical connection between the pixel electrode 19 and the TFT 60 through the pixel contact hole 45 is ensured, and the liquid crystal with improved electrical reliability is also obtained. A display device can be realized.
<Other embodiments>
In the above embodiment, the case where the pixel electrode 19 and the counter electrode 21 of the liquid crystal display device 100 are formed by applying the method for forming a transparent conductive film according to the present invention has been described, but the method for forming a transparent conductive film according to the present invention is described. Can also be used without problems in forming an electrostatic protection film provided on the outer surface of the substrate of the liquid crystal display device. Hereinafter, a description will be given with reference to FIGS. 10 and 11.

  FIG. 10 is a plan configuration diagram of one sub-pixel of the liquid crystal display device 200 of the present embodiment, and FIG. 11 is a cross-sectional configuration diagram taken along the line D-D ′ in FIG. 10. The liquid crystal display device 200 according to the present embodiment is a liquid crystal display device that drives a liquid crystal by a so-called lateral electric field method and displays an image. Among the horizontal electric field methods, the FFS (Fringe Field Switching) method is used in particular. . Since the liquid crystal display device 200 of this embodiment is common to the liquid crystal display device 100 according to the previous embodiment in its basic configuration, the same components as those of the liquid crystal display device 100 in FIGS. 10 and 11 are the same. Reference numerals are assigned and detailed description is omitted.

  Note that the liquid crystal layer 50 of the liquid crystal display device 200 according to the present invention is different from the previous embodiment in that liquid crystal molecules are aligned between the TFT array substrate 10 and the counter substrate 20 in parallel to the substrate surface. A liquid crystal having a dielectric anisotropy of 2 is used.

  As shown in FIG. 10, the sub-pixels of the liquid crystal display device 200 include a pixel electrode 119 having a substantially ladder shape in plan view, a common electrode 129 formed at a position substantially overlapping the pixel electrode 119 in plan view, and a pixel electrode 119. TFT 60 electrically connected to each other, scanning line 18a and data line 16 electrically connected to TFT 60 and extending along the vertical and horizontal edges of pixel electrode 119, and extending along scanning line 18a In addition, a capacitor line 18b electrically connected to the common electrode 129 is provided.

  In the cross-sectional structure shown in FIG. 11, the TFT 60 is formed on the inner surface side of the substrate body 10A of the TFT array substrate 10, and the capacitor line 18b and the common electrode are formed in the same layer as the gate electrode 32 (scanning line 18a) of the TFT 60. 129 is formed. The common electrode 129 is a transparent conductive film formed using a transparent conductive material such as ITO, and the method for forming a transparent conductive film of the present invention can also be applied when forming the common electrode 129. An insulating thin film 36 is formed so as to cover the common electrode 129, and a first interlayer insulating film 37 and a second interlayer insulating film 38 are sequentially stacked so as to cover the TFT 60 and the insulating thin film 36. The substantially ladder-shaped pixel electrode 119 described above is formed on the second interlayer insulating film 38, and the alignment film 39 is formed so as to cover the pixel electrode 119. Of course, the method for forming a transparent conductive film of the present invention may be applied to the formation of the pixel electrode 119.

  A light shielding film 23 and a color filter 22 are formed on the inner surface side of the substrate body 20 </ b> A constituting the counter substrate 20, and an alignment film 28 is formed on the color filter 22. An electrostatic protection film 121 made of a flat solid transparent conductive film is formed on the outer surface side of the substrate body 20A, and a retardation plate 26 and a polarizing plate 24 are disposed on the electrostatic protection film 121. Yes.

  The liquid crystal display device 200 having the above configuration forms an electric field substantially in the direction of the substrate surface by applying a voltage to the pixel electrode 119 via the TFT 60 by a potential difference between the pixel electrode 119 and the common electrode 129. The liquid crystal is driven by the electric field substantially in the direction of the substrate surface, and the transmitted light is modulated based on the difference in the alignment state of the liquid crystal to display an image.

  As described above, in the horizontal electric field type liquid crystal display device 200, the pixel electrode 119 and the common electrode 129 which are electrodes for forming an electric field for driving the liquid crystal are both formed on the TFT array substrate 10, and the counter substrate is formed. No electrode is formed on the liquid crystal layer 50 side of 20. For this reason, when static electricity enters from the counter substrate 20 side and the substrate body 20A is charged, the electric field formed by the charges acts on the liquid crystal layer 50, which may cause alignment disorder of the liquid crystal and display failure. Therefore, in the horizontal electric field type liquid crystal display device, a transparent conductive film is formed as an electrostatic protective film on the outer surface side of the counter substrate 20 to absorb incident static electricity.

The method for forming a transparent conductive film according to the present invention can be applied to the process of forming the electrostatic protection film 121 described above, and is conductive at a relatively low temperature by using the method for forming a transparent conductive film according to the present invention. Can be formed. Therefore, according to the present embodiment, the liquid crystal display device 200 including the electrostatic protection film 121 can be manufactured without causing deterioration of the color filter 22 and the like by heating.
<Electronic equipment>
Next, specific examples of the electronic device of the present invention will be described.

  FIG. 12A is a perspective view showing an example of a mobile phone. Reference numeral 1000 denotes a mobile phone body, and 1001 denotes a display unit including the liquid crystal display device 100 of the above-described embodiment. FIG. 12B is a perspective view showing an example of a wristwatch type electronic device. Reference numeral 1100 denotes a watch body, and 1101 denotes a display unit including the liquid crystal display device 100 of the above embodiment. FIG. 12C is a perspective view illustrating an example of a portable information processing apparatus such as a word processor or a personal computer. Reference numeral 1200 denotes an information processing device, 1202 denotes an input unit such as a keyboard, 1204 denotes an information processing body, and 1206 denotes a display unit including the liquid crystal display device 100 of the above embodiment.

  Since the electronic apparatus shown in FIGS. 12A to 12C includes the liquid crystal display device 100 of the above embodiment, a highly reliable conductive film is used for an electrode member or the like. It has become an excellent electronic device. Also, the manufacturing method of the above embodiment can be applied to large liquid crystal panels such as televisions and monitors.

  In addition, although the electronic device of this embodiment shall be provided with the liquid crystal display device 100, it can also be set as the electronic device provided with other electro-optical apparatuses, such as an organic electroluminescent display apparatus and a plasma type display apparatus.

The block diagram of the liquid material containing the electroconductive fine particles and Ag microparticles | fine-particles concerning one Embodiment. The graph which shows the relationship between the resistance value with respect to the addition rate of Ag microparticles | fine-particles in the liquid material which concerns on one Embodiment, and the transmittance | permeability. Process drawing which shows the formation method of the transparent conductive film using the liquid material which concerns on one Embodiment. The figure which shows a droplet discharge device and a discharge head. Process drawing which shows the formation method of the transparent conductive film using the liquid material which concerns on other embodiment. The circuit block diagram of the liquid crystal display device which concerns on one Embodiment. 1 is an overall configuration diagram of a liquid crystal display device according to an embodiment. The pixel block diagram of the liquid crystal display device which concerns on one Embodiment. The pixel block diagram of the liquid crystal display device which concerns on other embodiment. The cross-sectional block diagram of the liquid crystal display device which concerns on other embodiment. The circuit block diagram of the liquid crystal display device which concerns on one Embodiment. The perspective view which illustrates an electronic device.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 11, 11 '... Conductive fine particle, 12 ... Ag fine particle, 13 ... Dispersion medium, 14A ... Liquid material (liquid material for transparent conductive film formation), 14B ... Solidified material, 14C ... Transparent conductive film, 19,119 ... Pixel electrode , 21 ... counter electrode, 121 ... electrostatic protective film, 100, 200 ... liquid crystal display device (electro-optical device)

Claims (11)

  A liquid material for forming a transparent conductive film, comprising conductive fine particles that exhibit translucency when converted to an oxide and metal fine particles made of Ag in a dispersion medium.   The liquid material for forming a transparent conductive film according to claim 1, wherein the conductive fine particles contain one or more elements selected from In, Zn, Al, F, and Sn.   A liquid material for forming a transparent conductive film, comprising conductive fine particles made of a light-transmitting oxide film and metal fine particles made of Ag in a dispersion medium.   4. The liquid material for forming a transparent conductive film according to claim 3, wherein the conductive fine particles are made of an oxide containing one or more elements selected from In, Zn, Al, F and Sn.   5. The transparent conductive film according to claim 1, wherein the content of the metal fine particles is mixed so as to be 0.01 to 10 wt% with respect to the conductive fine particles. Forming liquid material.   6. The liquid material for forming a transparent conductive film according to claim 5, wherein the content of the metal fine particles is mixed so as to be 0.5 to 2 wt% with respect to the conductive fine particles. A step of disposing on the substrate conductive fine particles that exhibit translucency when converted to an oxide, and a liquid material for forming a transparent conductive film containing a metal fine particle made of Ag in a dispersion medium;
Forming a solidified product of the transparent conductive film-forming liquid material by heat-treating the transparent conductive film-forming liquid material on the substrate in a reduced pressure or reducing atmosphere; and
Heat-treating the solidified product in an oxygen-containing atmosphere to oxidize the solidified product;
A method for forming a transparent conductive film, comprising: Arranging a liquid material for forming a transparent conductive film, which includes conductive fine particles made of a light-transmitting oxide film and metal fine particles made of Ag in a dispersion medium, on a substrate;
Heat-treating the transparent conductive film-forming liquid material on the substrate in a reduced pressure or reducing atmosphere;
A method for forming a transparent conductive film, comprising:   The method for forming a transparent conductive film according to claim 7 or 8, wherein heating temperatures in the plurality of heat treatments are all 300 ° C or lower. A method of manufacturing an electro-optical device having a transparent conductive film on a substrate,
A step of disposing on the substrate conductive fine particles that exhibit translucency when converted into an oxide and a liquid material for forming a transparent conductive film containing metal fine particles made of Ag in a dispersion medium;
Forming a solidified product of the transparent conductive film-forming liquid material by heat-treating the transparent conductive film-forming liquid material on the substrate in a reduced pressure or reducing atmosphere;
Heating the solidified material in an oxygen-containing atmosphere to oxidize the solidified material to form the transparent conductive film;
A method for manufacturing an electro-optical device. A method of manufacturing an electro-optical device having a transparent conductive film on a substrate,
Arranging a liquid material for forming a transparent conductive film, which includes conductive fine particles made of a light-transmitting oxide film and metal fine particles made of Ag in a dispersion medium, on a substrate;
Forming a transparent conductive film by heating the transparent conductive film-forming liquid material on the substrate in a reduced pressure or reducing atmosphere; and
A method for manufacturing an electro-optical device.

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