JP2008021617A - Liquid material, forming method of transparent conductive film, and manufacturing method of electro-optical device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid material capable of forming a transparent conductive film having electric characteristics which are stable even in a low temperature process. <P>SOLUTION: The liquid material of this invention is characterized in dispersing, in a dispersion medium, oxide particulate 12 made of oxides including one or more elements selected from a group of In, Zn, Al, F, and Sn, and metal particulate 13 made of metal materials including one or more elements selected from a group of In, Zn, Al, F, and Sn. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

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

A transparent conductive film using a transparent conductive material such as ITO (indium tin oxide) is used as an electrode of a display device such as a liquid crystal display device. 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 plane 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, the method using the pyrolysis material described in Patent Document 3 may be caused by the generation of carbon residue and the deterioration of the crystallinity of the conductive film due to the fact that the pyrolysis material does not completely decompose.

  The present invention has been made in view of the above-mentioned problems of the prior art, and provides a liquid material for forming a transparent conductive film capable of forming a transparent conductive film having stable electrical characteristics even in a low-temperature process. It is an object. 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.

In order to solve the above problems, the liquid material of the present invention includes oxide fine particles composed of an oxide containing one or more elements selected from In, Zn, Al, F, and Sn, and In, Zn, Al, A metal fine particle made of a metal material containing one or more elements selected from F and Sn is dispersed in a dispersion medium. That is, the liquid material of the present invention is characterized in that oxide fine particles made of a transparent conductive material and metal fine particles made of a constituent metal of the transparent conductive material are dispersed in a dispersion medium.
In the case of forming a transparent conductive film using a liquid material having such a structure, there are a step of removing the dispersion medium from the liquid material by heat treatment, and a step of oxidizing the metal fine particles by conversion to a transparent conductive material by oxidation treatment. Done. If the liquid material of the present invention is used, a stable contact can be formed by the fusion action of the metal fine particles contained in the liquid material in the heating step. Further, when the metal fine particles are oxidized to be converted into a transparent conductive material, the crystallinity of the oxide generated by the conversion of the metal fine particles can be enhanced by the action of the oxide fine particles contained in the liquid material. As described above, in the liquid material of the present invention, the conductivity and reliability of the transparent conductive film formed by the interaction between the oxide fine particles and the metal fine particles constituting the liquid material are enhanced. Therefore, according to this invention, the liquid material which can form the transparent conductive film which is low resistance and excellent in reliability can be provided.

  In the liquid material of the present invention, it is preferable that the oxide fine particles are made of indium tin oxide, and the metal fine particles are made of a metal material mainly containing In and Sn. According to this configuration, the liquid material can form a transparent conductive film made of indium tin oxide having excellent conductivity and excellent reliability.

  The method for forming a transparent conductive film of the present invention includes oxide fine particles composed of an oxide containing one or more elements selected from In, Zn, Al, F, and Sn, and In, Zn, Al, F, and Sn. A step of disposing a liquid material obtained by dispersing metal fine particles made of a metal material containing one or more elements selected from the above in a dispersion medium on the substrate; and the liquid material on the substrate in a vacuum atmosphere or an inert atmosphere. Or a step of heat-treating in a reducing atmosphere to form a solidified product of the liquid material, and a step of heat-treating the solidified product in an oxygen-containing atmosphere to oxidize the solidified product. To do. According to this forming method, a stable contact can be formed on the solidified product by fusing metal fine particles generated by heat treatment under reduced pressure or in a reducing atmosphere. Thus, the metal fine particles can be converted into an oxide having high crystallinity. Therefore, according to the present invention, it is possible to easily form a transparent conductive film having low resistance and excellent reliability.

  In the method for forming a transparent conductive film of the present invention, the heating temperatures in the plurality of heat treatments are all 300 ° C. or lower. According to this method, it is possible to form a transparent conductive 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.

The method for manufacturing an electro-optical device is a method for manufacturing an electro-optical device having a transparent conductive film on a substrate, and includes an oxide containing one or more elements selected from In, Zn, Al, F, and Sn. A liquid material obtained by dispersing oxide fine particles and metal fine particles made of a metal material containing one or more elements selected from In, Zn, Al, F, and Sn in a dispersion medium is disposed on the substrate. A step of heat-treating the liquid material on the substrate in a vacuum atmosphere, an inert atmosphere, or a reducing atmosphere to form a solidified product of the liquid material; and heat-treating the solidified material in an oxygen-containing atmosphere. And oxidizing the solidified product to form the transparent conductive film.
According to this manufacturing method, an electro-optical device having a transparent conductive film having excellent conductivity and reliability can be easily manufactured, and an electro-optical device having excellent display characteristics and reliability is provided. Can do.

(Liquid material)
Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a diagram showing two types of fine particles constituting the liquid material according to the present invention. As shown in FIG. 1, the liquid material of the present invention includes oxide fine particles 12 and metal fine particles 13, which are dispersed in a dispersion medium.

The oxide fine particles 12 are made of an oxide containing one or more elements selected from In, Zn, Al, F, and Sn, that is, a granular material of a transparent conductive material. Specifically, ITO (In—Sn—O), ATO (Sn—Sb—O), FTO (F—Sn—O), AZO (Zn—Al—O), IZO (In—Zn—O), A composite oxide such as GZO (Ga—Zn—O) or a metal oxide such as In ₂ O ₃ , ZnO, or SnO ₂ can be exemplified. The oxide fine particles 12 can be produced using a known fine particle production 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 oxide fine particles 12.

  In addition, the fine particles formed by using the gas phase method or the liquid phase method are subjected to a heat treatment at about 500 ° C. to 800 ° C., thereby producing oxide fine particles 12 with improved crystallinity of the oxide constituting the fine particles. It is preferable to do. By increasing the crystallinity of the oxide constituting the oxide fine particles 12, when the transparent conductive film is formed using the oxide fine particles 12, the oxide fine particles 12 have good crystallinity, low resistance and reliability. An excellent transparent conductive film can be obtained.

  The particle diameter of the oxide fine particles 12 is preferably about 1 nm to 0.1 μm, and more preferably in the range of 1 nm to 40 nm. By using a material having a particle size of 0.1 μm or less, clogging can be prevented when the liquid material containing the oxide fine particles 12 is ejected from the droplet ejection 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 formed using the oxide fine particle 12.

  The metal fine particles 13 are made of a metal film containing one or more elements selected from In, Zn, Al, F, and Sn, that is, a metal material that can generate a transparent conductive material by oxidation treatment. It is preferable. Therefore, specific constituent materials of the metal fine particles 13 include In—Sn alloy, Sn—Sb alloy, F—Sn alloy, Zn—Al alloy, In—Zn alloy, Ga—Zn alloy, or In, Zn, Sn. Examples of such a metal material can be exemplified. As a method for forming the metal fine particles 13, a known method can be applied regardless of a liquid phase method or a gas phase method, and an appropriate method may be selected according to the material of the metal fine particles 13.

  The particle diameter of the metal fine particles 13 is preferably about 1 nm to 0.1 μm, and more preferably in the range of 1 nm to 40 nm. By using a material having a particle size of 0.1 μm or less, clogging can be prevented when the liquid material containing the metal fine particles 13 is ejected from the droplet ejection head. In addition, if the range is from 1 nm to 40 nm, a uniform oxide can be easily obtained when the metal fine particles 13 are oxidized to form a transparent conductive material, and the formed transparent conductive film has good conductivity and transparency. Obtainable.

  The particle size of the metal fine particles 13 may be approximately the same as the particle size of the oxide fine particles 12 or may be finer than the oxide fine particles 12. Since the metal fine particles 13 have a function of forming a stable contact in the transparent conductive film to be formed, the metal fine particles 13 are preferably arranged in contact with the oxide fine particles 12 when the dispersion medium is removed. It is preferable to use fine metal particles 13.

  Note that the surfaces of the oxide fine particles 12 and the metal fine particles 13 may be coated with an organic substance for the purpose of preventing aggregation of the fine particles when the liquid material is prepared by being dispersed in a dispersion medium.

The liquid material of the present embodiment is a liquid material in which the above-described oxide fine particles 12 and metal fine particles 13 are dispersed in a dispersion medium.
The dispersion medium is not particularly limited as long as the oxide fine particles 12 and the metal fine particles 13 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 hydrocarbon compounds are preferred in view of dispersibility of the oxide fine particles 12 and metal fine particles 13, stability of the dispersion, and ease of application to the droplet discharge method (inkjet method). Ether compounds are preferred, and more preferred dispersion media include water and hydrocarbon compounds.

  The surface tension of the liquid material (dispersion) is preferably in the range of 0.02 N / m to 0.07 N / m. When the liquid material is ejected by the ink jet method, if the surface tension is less than 0.02 N / m, the wettability of the ink composition to the nozzle surface increases, and thus flight bending easily occurs. If it exceeds the upper limit, the shape of the meniscus at the nozzle tip is not stable, and it becomes difficult to control the discharge amount and the discharge timing. In order to adjust the surface tension, a small amount of a surface tension regulator such as a fluorine-based, silicone-based, or non-ionic-based one may be added to the dispersion within a range that does not significantly reduce the contact angle with the substrate. The nonionic surface tension modifier improves the wettability of the liquid to the substrate, improves the leveling property of the film, and helps prevent the occurrence of fine irregularities in the film. The surface tension modifier may contain an organic compound such as alcohol, ether, ester, or ketone, if necessary.

  The viscosity of the dispersion is preferably 1 mPa · s to 50 mPa · s. When a liquid material 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 hole The clogging frequency in the case becomes high, and not only is 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 a transparent conductive film using a liquid material containing oxide fine particles 12 and metal fine particles 13 will be described.
FIG. 2A is a schematic process diagram showing a method for forming a transparent conductive film of this embodiment, and FIG. 2B is a sectional process diagram of the transparent conductive film corresponding to each process shown in FIG. . FIG. 3 is an operation explanatory diagram of the method for forming the transparent conductive film.
In the present embodiment, as an example of a method for forming a transparent conductive film, a method for forming a transparent conductive film 11C on a substrate P will be described as shown in FIG.

  In the method for forming a transparent conductive film of the present embodiment, as shown in FIGS. 2A and 2B, a liquid material 11A containing oxide fine particles 12 and metal fine particles 13 is applied on a substrate P. The first step ST1 and the second step of forming the solidified material 11B of the liquid material 11A on the substrate P by drying and solidifying the liquid material 11A by applying heat treatment to the liquid material 11A applied on the substrate P. ST2 and a third step ST3 for converting the solidified material 11B into the transparent conductive film 11C by oxidizing the solidified material 11B on the substrate P.

As the substrate P shown in FIG. 2B, a flexible substrate such as plastic can be used in addition to a hard substrate such as glass, quartz, and ceramics. The liquid material 11A is made of a dispersion in which the oxide fine particles 12 and the metal fine particles 13 are dispersed in a dispersion medium such as an organic solvent.
In the first step ST1, the liquid material 11A is applied on the substrate P. The method for applying the liquid material is not particularly limited, and various methods can be adopted. For example, a liquid droplet discharge method, a CAP coating method, a die coating method, or a curtain coating method can be used. It can be used depending on the form.

When a transparent conductive film 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 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 in the region partitioned by the bank, a transparent conductive film having a desired planar shape can be formed on the substrate P with an accurate position and shape.

As shown in FIG. 2B, when the liquid material 11A is discharged and arranged on the substrate P using the above-described droplet discharge device IJ, in order to remove the dispersion medium from the liquid material 11A on the substrate P. Then, a second step ST2 which is a heat treatment step is performed. The second step ST2 is performed under a vacuum atmosphere, an inert atmosphere, or a reducing atmosphere. That is, the second step ST2 is performed in an environment excluding oxygen. As such an environment, a vacuum atmosphere reduced to 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 or H ₂ gas. A reducing atmosphere such as a mixed gas of methane and inert gas, CO gas, a mixed gas of CO gas and CO ₂ gas, or the like can be exemplified.

  The treatment temperature of the second step ST2 is the boiling point (vapor pressure) of the dispersion medium, 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, and the heat resistance of the substrate. The temperature may be determined in consideration of the temperature. For example, in order to remove the coating material made of organic matter, it is necessary to bake 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 second step ST2 is performed for the purpose of removing the dispersion medium contained in the liquid material 11A and promoting fusion between the metal fine particles 13 or between the metal fine particles 13 and the oxide fine particles 12. By the heat treatment in the second step ST2, as shown in FIGS. 2B and 3A, the dispersion medium is removed from the liquid material 11A, and the oxide fine particles 12 and the metal fine particles 13 are aggregated. Thus, the solidified material 11B in contact with each other is formed on the substrate P. In addition, when the surface of the oxide fine particles 12 and the surface of the metal fine particles 13 are provided with an organic coating for preventing aggregation, this coating is also decomposed and removed in the second step ST2.

Furthermore, in this embodiment, the metal fine particles 13 are made of a metal material containing one or more elements selected from In, Zn, Al, F, and Sn, and contain a metal that melts at a relatively low temperature. Even at a heating temperature of 300 ° C. or less, part or all of the metal fine particles 13 melt and are fused to the metal fine particles 13 or the oxide fine particles 12 adjacent to the metal fine particles 13.
As described above, in the second step ST2, by performing heat treatment on the liquid material 11A in a vacuum atmosphere, an inert atmosphere, or a reducing atmosphere, the metal fine particles 13 made of the metal material are partially or totally. It is possible to advance the fusion of the oxide fine particles 12 and the metal fine particles 13 with the metal fine particles 13 while preventing them from being oxidized. Therefore, a very stable contact can be formed between the particles by the second step ST2.

The second step ST2 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 condition is 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 ST2 is executed very quickly. be able to.

If the solidified material 11B is formed on the substrate P, the third step ST3 for converting the solidified material 11B into the transparent conductive film 11C by oxidizing is performed. The third step ST3 is performed, for example, by selectively heating the solidified material 11B in an oxygen-containing atmosphere or by heating the whole including the substrate P. 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 11B in an oxygen-containing atmosphere in this manner, the metal fine particles 13 surrounding the oxide fine particles 12 are oxidized to become metal oxides as shown in FIGS. 2 (b) and 3 (b). The solidified material 11B can be converted into the transparent conductive film 11C. At this time, the metal oxide particles formed by oxidation of the metal fine particles 13 become a metal oxide having good crystallinity due to the crystallinity of the oxide fine particles 12 located nearby, The transparent conductive film 11C is a low-resistance conductive film having good crystallinity as a whole. In addition, since a stable contact is formed between the particles by fusion of the metal fine particles 13 in the second step ST2, in the transparent conductive film 11C formed by oxidizing the solidified product 11B, the oxidation that constitutes the transparent conductive film 11C. The contact between the object fine particles 12 is stable, and a transparent conductive film having excellent reliability is obtained.

As described above, according to the method for forming a transparent conductive film of the present invention, a special effect that cannot be obtained by the conventional technique can be obtained as follows. First, in a transparent conductive film formed by applying a liquid material containing conventional ITO fine particles onto a substrate, and drying and baking the liquid material, 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. On the other hand, in the present invention, a stable contact can be formed between the oxide fine particles 12 and the metal fine particles 13 or between the metal fine particles 13 by the fusion action of the metal fine particles 13 in the second step ST2. The obtained transparent conductive film also has a stable contact, and excellent reliability can be obtained.
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. On the other hand, in the present invention, since the fine oxide particles 12 made of an oxide having good crystallinity are contained in the liquid material 11A, when the fine metal particles 13 are oxidized in the third step ST3, the fine particles 12 are close to The fine metal particles 13 can be converted into a metal oxide having good crystallinity following the crystal structure of the fine oxide particles 12 located. Therefore, according to the formation method of this embodiment, a low-resistance transparent conductive film excellent in crystallinity can be obtained.

(Electro-optical device and manufacturing method thereof)
The transparent conductive film 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. 6 is an overall configuration diagram of the liquid crystal display device 100. FIG. 7 is a diagram showing a planar configuration of a TFT array substrate in a pixel composed of three subpixels. FIG. 8 is a partial cross-sectional configuration diagram of the liquid crystal display device 100 taken along line B-B ′ of FIG. 7.

  As shown in FIG. 5, 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 of a plurality of data lines 16 adjacent to each other.

  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 FIGS. 6 and 8, in the liquid crystal display device 100 of the present embodiment, a TFT array substrate (first substrate) 10 and a counter substrate (second substrate) 20 are bonded together by a sealing material 52, and this sealing material. In this configuration, the liquid crystal layer 50 is sealed in a region partitioned by 52. 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 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. 7 and 8.
As shown in FIG. 8, 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 configuration diagram of FIG. 7, the sub-pixel of the liquid crystal display device 100 is provided with a pixel electrode 19 and a TFT 60 that 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. 7 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, when the cross-sectional structure shown in FIG. 8 is seen, 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 these 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 transparent 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 11A including the oxide fine particles 12 and the metal fine particles 13 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 11A 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 11A is heated to dry and solidify it to obtain a solidified product 11B. By heating this in an oxygen atmosphere, the solidified product 11B is heated. The pixel electrode 19 can be formed by converting to the transparent conductive film 11C. 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 is excellent in electrical reliability without causing any contact failure.

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 11A including the oxide fine particles 12 and the metal fine particles 13 according to the present invention is disposed on the color filter 22 by using a spin coat 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 11A is heated to dry and solidify it to obtain a solidified product 11B. By heating this in an oxygen atmosphere, the solidified product 11B is heated. The counter electrode 21 can be formed by converting the light into a transparent conductive film 11C. 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 11A 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. 9 and 10.

FIG. 9 is a plan configuration diagram of one sub-pixel of the liquid crystal display device 200 of the present embodiment, and FIG. 10 is a cross-sectional configuration diagram taken along the line DD ′ of FIG. 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. 9 and 10 are the same. Reference numerals are assigned and detailed description is omitted.
The liquid crystal layer 50 of the liquid crystal display device 200 according to the present embodiment is different from the previous embodiment in that liquid crystal molecules are aligned parallel to the substrate surface between the TFT array substrate 10 and the counter substrate 20. Liquid crystals having positive dielectric anisotropy are used.

  As shown in FIG. 9, 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. 10, 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.

  Although the transmissive liquid crystal display device has been described in the above embodiment, the present invention can be applied to general electro-optical devices having a transparent electrode. Therefore, in addition to the transmission type liquid crystal display device, the present invention can be applied to a reflection type liquid crystal display device and a transflective type liquid crystal display device. Can be applied.

(Electronics)
Next, specific examples of the electronic device of the present invention will be described.
FIG. 11A 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. 11B 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. 11C is a perspective view showing 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. 11A to 11C includes the liquid crystal display device 100 of the above-described embodiment, reliability is improved by using a highly reliable conductive film 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 cross-sectional block diagram of the oxide microparticles | fine-particles which concern on this invention. Process drawing which shows the formation method of the transparent conductive film which concerns on this invention. The action explanatory view of the oxide particulates concerning the present invention. The figure which shows a droplet discharge device and a discharge head. The circuit block diagram of the liquid crystal display device which concerns on 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 embodiment. 1 is a cross-sectional 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 other embodiment. The cross-sectional block diagram of the liquid crystal display device which concerns on other embodiment. The perspective view which illustrates an electronic device.

Explanation of symbols

  11A liquid material, 11B solidified material, 11C transparent conductive film, 12 oxide fine particles, 13 metal fine particles, 19,119 pixel electrode, 21 counter electrode, 121 electrostatic protection film, 100, 200 liquid crystal display device (electro-optical device)

Claims (7)

  Oxide fine particles made of an oxide containing one or more elements selected from In, Zn, Al, F, and Sn, and a metal containing one or more elements selected from In, Zn, Al, F, and Sn A liquid material obtained by dispersing metal fine particles made of a material in a dispersion medium.   A liquid material, wherein oxide fine particles made of a transparent conductive material and metal fine particles made of a constituent metal of the transparent conductive material are dispersed in a dispersion medium.   3. The liquid material according to claim 1, wherein the oxide fine particles are made of indium tin oxide, and the metal fine particles are made of a metal material mainly containing In and Sn.   The liquid material according to any one of claims 1 to 3, wherein a volume content of the oxide fine particles is a content that is equal to or higher than a volume content of the metal fine particles. Oxide fine particles made of an oxide containing one or more elements selected from In, Zn, Al, F, and Sn, and a metal containing one or more elements selected from In, Zn, Al, F, and Sn Placing a liquid material obtained by dispersing metal fine particles made of a material in a dispersion medium on a substrate;
Heat-treating the liquid material on the substrate in a vacuum atmosphere, an inert atmosphere, or a reducing atmosphere to form a solidified product of the liquid material;
Heat-treating the solidified product in an oxygen-containing atmosphere to oxidize the solidified product;
A method for forming a transparent conductive film, comprising:   The method for forming a transparent conductive film according to claim 5, wherein heating temperatures in the plurality of heat treatments are all 300 ° C. or less. A method of manufacturing an electro-optical device having a transparent conductive film on a substrate,
Oxide fine particles made of an oxide containing one or more elements selected from In, Zn, Al, F, and Sn, and a metal containing one or more elements selected from In, Zn, Al, F, and Sn Arranging a liquid material obtained by dispersing metal fine particles made of a material in a dispersion medium on a substrate;
Forming a solidified product of the liquid material by heat-treating the liquid material on the substrate in a vacuum atmosphere, an inert atmosphere, or a 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.

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