JP4957108B2 - Color filter and manufacturing method thereof - Google Patents

Description

  The present invention relates to a color filter and a manufacturing method thereof.

  In a liquid crystal display, a color filter formed by sequentially forming a black matrix layer and a colored layer on a transparent substrate uses beads to form a gap (interval) with a thin film transistor (TFT) array substrate serving as a counter electrode. Scattered to ensure a uniform distance between them. Recently, for the purpose of pixel defects caused by the dispersion of beads, liquid crystal display cost reduction, liquid crystal panel gap uniformization, etc., a method has been established in which a transparent resin material is formed into a columnar shape on a black matrix and used as a spacer. Has been.

  In addition, in the case of a vertical alignment type (VA) liquid crystal display device after laminating a colored layer on the black matrix layer, a resin for forming a transparent pattern for controlling the liquid crystal alignment is formed on the colored layer for orientation. A technique for forming protrusions has been established, and production methods for further cost reduction have been used.

  Here, in the case of a VA liquid crystal display device, a transparent conductive film is formed on a spacer formed by laminating colored layers, and further, alignment protrusions for controlling liquid crystal alignment are formed. Further, since a resin is formed, an electrical short circuit with the TFT substrate can be prevented.

  However, since a vertical foreign matter may be caused by a minute foreign matter or the like, a method of forming an insulating layer has been proposed (for example, see Patent Document 1).

  On the other hand, in a parallel electric field type (IPS) liquid crystal display device, a columnar resin spacer or a spacer made of a laminate of colored layers is used in the same manner. Since it is not necessary to form a transparent electrode on the color filter, no countermeasure against a short circuit is required.

  It has been proposed to form a planarization layer (overcoat) for planarizing the color filter. However, the columnar spacer formed by sequentially laminating the colored layers is buried when the flattening layer is formed, and there is a problem that the intended space securing function cannot be sufficiently achieved.

  This flattening layer also serves to prevent the impurity ions eluted from the color filter from being mixed into the liquid crystal. The resin used for the color filter layer has been devised so that such impurity ions are not mixed into the liquid crystal, and recently, a liquid crystal panel can be produced without forming an overcoat layer.

  However, an overcoat is indispensable for applications in which display characteristics are changed by a very small amount of eluted components. In addition, it may be necessary to form an overcoat layer for flattening the color filter layer. In the flattening process, polishing is performed after the color filter layer is formed, and a step for removing the step of the overlapping portion of the resin is provided. There is also a method to do.

When this flattening is required, the standard of the step differs depending on the liquid crystal and its driving method.
JP, 2005-208583, A In recent years, the price of a liquid crystal display has fallen and the spread to a general household has continued greatly, and has become a big market. One of the reasons for this market expansion is the decline in prices. For this reason, the unit price of the color filter used for the panel is also decreasing at a very fast speed.

  Devising ideas for reducing the unit price of a color filter is the utmost proposition in the production of a color filter. In addition to this, functions such as improved image quality, higher definition, and higher viewing angle are also required at the same time, and efforts to simultaneously improve performance and reduce costs are required.

  There are various functions of the spacer for securing the panel gap described above, but the spacer formed by laminating the coloring material on the black matrix separately from the pixel from the efforts to reduce the cost separately forms a columnar resin layer. The number of processes is one less than in the case, leading to a reduction in materials, and is attracting attention as a technology that satisfies the above requirements.

  However, simply forming the color spacers to form columnar spacers is not suitable for liquid crystal panels used in a wide range of applications. For example, if the ions eluted from the color filter layer cannot be mixed into the liquid crystal, it is good. Display quality cannot be maintained.

  For this reason, it has been proposed to form a resin overcoat to form a protective layer. However, the resin overcoat impairs the shape of the columnar spacers, adversely affecting the liquid crystal alignment and obtaining desired display characteristics. There was a problem that it was not possible.

  The present invention has been made in order to solve the above-described problems of the prior art, and there is no mixing of ions from the color filter into the liquid crystal, and the color for the liquid crystal display does not impair the display quality of the display. It aims at providing a filter and its manufacturing method.

In order to solve the above problems, a first aspect of the present invention is a color filter for a liquid crystal display in which a black matrix layer and a plurality of colored layers are formed on a transparent substrate, wherein the colored matrix is formed on the black matrix layer. further comprising a columnar spacer formed a colored material forming the layers by stacking more than one color, the multiple colors of the colored layer surface and the columnar spacers surface, the film thickness is 50 nm to 300 nm SiN _x, SiO _x Provided is a color filter for a liquid crystal display, which is coated with a transparent thin film made of an amorphous inorganic material selected from the group consisting of N _y and SiO ₂ .

  The height of the columnar spacer formed by laminating one or more coloring materials is preferably 3 to 5 μm from the surface of the coloring layer.

  The color filter according to the first aspect of the present invention as described above can be suitably used for IPS.

The second aspect of the present invention is a step of forming a black matrix layer having a predetermined pattern on a transparent substrate, applying a coloring material to the opening region divided by the black matrix layer, exposing and developing. A step of forming a plurality of colored layers by repeating for each color of the coloring material, laminating one or more coloring materials on the black matrix layer to form a columnar spacer, and the surface of the colored layer There is provided a method for producing a color filter for a liquid crystal display, comprising a step of forming a transparent thin film made of an amorphous inorganic material having a film thickness of 50 nm to 300 nm on the upper and columnar spacer surfaces.

  In such a method for producing a color filter for a liquid crystal display, a transparent thin film can be formed by a plasma CVD method. Alternatively, the transparent thin film can be formed by a reactive sputtering method. In any method, it is desirable to form the transparent thin film at a temperature of 200 ° C. or lower.

  In the method for producing a color filter according to the second aspect of the present invention, the surface of the colored layer and the columnar spacer is subjected to a polishing treatment to remove residues on the surface and further to adjust the height of the columnar spacer. can do. This polishing can be performed using an abrasive mainly composed of aluminum oxide.

  According to the present invention, since the columnar spacer formed by laminating the coloring material on the black matrix layer when the colored layer is formed is covered with the transparent thin film having a predetermined thickness, the shape of the columnar spacer is impaired. In addition, mixing of ions eluted from the colored layer into the liquid crystal can be effectively prevented, thereby providing a color filter with good characteristics.

  The best mode for carrying out the invention will be described below.

  FIG. 1 is a cross-sectional view showing a color filter substrate for IPS according to the first embodiment of the present invention. In FIG. 1, a black matrix layer 2 having a predetermined pattern is formed on a glass substrate 1, and red pixels 3 a, green pixels 3 b, blue color are formed in opening regions on the glass substrate 1 partitioned by the black matrix layer 2. Pixels 3c are sequentially formed. In this case, when each pixel is formed, a coloring material is also laminated on the predetermined black matrix layer 2 to form a columnar spacer 4 including a red portion 4a, a green portion 4b, and a blue portion 4c. By forming the transparent thin film 5 on such a structure, the color filter substrate shown in FIG. 1 is constructed.

  FIG. 2 is a cross-sectional view showing a TN color filter substrate according to a second embodiment of the present invention. The color filter substrate according to this embodiment is for IPS according to the first embodiment of the present invention shown in FIG. 1 except that a transparent electrode (ITO film) 6 is formed under the transparent thin film 5. It has the same structure as the color filter substrate.

  In the color filter substrate according to the first and second embodiments of the present invention shown in FIGS. 1 and 2, the transparent thin film is formed on the columnar spacer 4 formed by laminating the colored layers 3a, 3b, 3c and the coloring material. 5 is formed, the transparent thin film 5 can maintain the shape of the columnar spacer and can effectively prevent ions eluted from the colored layers 3a, 3b, and 3c.

  The film thickness of the transparent thin film 5 needs to be in the range of 50 to 300 nm. The columnar spacer 4 formed by laminating coloring materials usually has a height of about 3 to 5 μm, and this height needs to be controlled with an accuracy of 10% or less. In order to control such a film thickness and height, the transparent thin film 5 needs to be formed as thin and uniform as possible. However, if the film thickness is too thin, the original purpose of preventing ion elution cannot be achieved.

  Further, since the surfaces of the colored layers 3a, 3b, and 3c that are not polished are uneven, a film thickness of a predetermined thickness or more is required. As a result of intensive studies, the present inventors have found that if the transparent thin film 5 has a thickness of 50 nm or more, the function of preventing elution of ions from being mixed into the liquid crystal can be achieved. On the other hand, if the film thickness is too thick, the function as a spacer cannot be performed as described above, and problems such as an increase in material cost and a decrease in throughput occur. Therefore, the upper limit of the film thickness is defined as 300 nm.

  The transparent thin film 5 is preferably made of a Si-based oxide or nitride, particularly in terms of barrier properties. A metal oxide is not desirable because it may cause ion migration while transferring electrons using metal bond bonds (existing as ions) and move to the surface layer.

In order to maintain ion barrier properties, an amorphous film is generally desirable. In a crystallized film, ions may permeate from the grain boundary, which is not desirable. Among the Si-based materials, SiO ₂ , SiN _x , and SiN _x O _{y that} are generally formed by plasma CVD have established formation methods, and materials are available at a relatively low cost, and the process is stable. This can be said to be desirable because it can be formed with few defects. In addition, there is an advantage that the apparatus cost is not required.

  The base on which the transparent thin film is formed has a shape with irregularities on the surface, such as convex portions of columnar spacers and gaps between colors of the colored layer, but when the transparent thin film is formed by plasma CVD, such an uneven surface In addition, since the step coverage is good and a dense thin film can be formed, the ion barrier property is also high and the adhesion of the film is also good. Furthermore, a thin film that does not impair the characteristics even at low temperatures can be formed.

In addition, it is possible to form a transparent thin film at a low cost by a reactive sputtering method for a liquid crystal display in which the base on which the transparent thin film is formed is relatively smooth and does not require much prevention of mixing of eluted ions. . In this case, oxygen or oxygen / nitrogen can be introduced into the Si source gas to form a SiO ₂ or SiN _x O _y film. Alternatively, RF (high frequency) sputtering or DC sputtering can be used. In the DC sputtering method, in the case of a Si-based transparent electrode, a target to which a trace amount of a dopant (for example, boron) is added can be used.

  The film forming temperature of the transparent thin film is desirably 200 ° C. or lower. If it exceeds 200 ° C., the colored layer is damaged, which is not desirable.

  In the production of the color filter substrate according to this embodiment, it is desirable to polish the surface after forming the colored layer and the columnar spacer. Thus, by polishing the surface, unnecessary step portions can be removed, and defects such as light leakage due to liquid crystal alignment collapse can be prevented. Further, by such polishing, the height of each layer, particularly the desired height of the columnar spacer can be adjusted to a desired value. Further, the step can be removed by polishing the overlapping portion of the black matrix layer and the colored layer.

  Furthermore, by carrying out polishing, the fine irregularities on the surface of the colored layer are flattened, and in particular, by removing residues such as development residues, peeling prevention and adhesion of the transparent thin film formed thereon are performed. It is possible to improve the performance. In addition, when a liquid crystal panel is manufactured, if there are dirt components such as residues, peeling failure of the sealing material occurs. By removing the dirt components by polishing, such defects can be prevented and reliability is improved. Leads to improvement.

  The polishing is particularly preferably performed using an abrasive mainly composed of aluminum oxide. Since the color filter layer is made of a resin, the surface is thinly scratched by the abrasive. For this reason, abrasives having a uniform particle size must be used in a more controlled state. The hardness of the abrasive is also an important factor. As a result of investigation, the present inventors have found that polishing can be performed without damaging the surface of the color filter layer by using an abrasive mainly composed of aluminum oxide.

  The color filter substrate according to the present invention can be suitably used particularly as a color filter substrate for IPS. In the TN liquid crystal display and the VA liquid crystal display, a transparent conductive film is formed on the color filter layer, and this serves to prevent the elution of impurity ions. It performs the same function.

  However, in the case of an IPS liquid crystal display, there is no transparent conductive film because the counter electrode is unnecessary, and the color filter layer is exposed. The present invention is particularly effective for an IPS liquid crystal display in such a state.

  Hereinafter, the present invention will be described more specifically by showing examples of the present invention.

Example 1
On a glass substrate, a black matrix material obtained by mixing carbon black in a photosensitive resin liquid is applied with a slit coater, exposed to ultraviolet rays using a photomask, partially cured on a predetermined pattern, and then developed and developed. Baking was performed to form a black matrix layer having a predetermined pattern.

  Next, a process of applying a photosensitive coloring material with a slit coater, exposing to ultraviolet rays using a photomask, partially curing the pattern, developing and baking is performed using R (red), G (green), and B ( The process was repeated in the order of (blue), and red, green, and blue pixels were formed in the opening area of the black matrix.

  At this time, a spacer was formed by sequentially laminating red, green and blue coloring materials in a dot pattern on the black matrix layer. The height of the stacked spacers was 3 μm higher than each pixel portion.

Next, the surface of the color filter layer thus formed was polished with an abrasive mainly composed of aluminum oxide. The polishing machine was an Oscar type polishing machine, and an abrasive having an average particle size of 0.2 microns was used. The polishing condition was 60 seconds at 30 rpm with a pressure of 0.02 kg / cm ² . After the polishing treatment, cleaning was performed to remove the abrasive and the polished resin component.

Thereafter, a SiN _x film was formed on the color filter layer by plasma CVD. First, after putting a board | substrate into a vacuum chamber, board | substrate temperature was 150 degreeC, exhausting. Next, after introducing SiH ₄ into 5 SCCM, NH ₃ into 25 SCCM, and H ₂ into a 250 SCCM vacuum chamber, RF with an output of 250 W was applied, and after 30 minutes, a SiN _x film having a thickness of 200 nm was obtained. This film covered the uneven shape of the color filter layer with good step coverage.

  When the color filter substrate obtained as described above is used for an IPS liquid crystal display device and a liquid crystal display panel is produced, there is no elution of ions from the color filter to the liquid crystal, and a liquid crystal display panel with good display characteristics is obtained. I was able to.

Example 2
On the glass substrate, a black matrix material made by mixing carbon black in a photosensitive resin solution is applied with a slit coater, exposed to ultraviolet light using a photomask, partially cured into a pattern, and then developed and baked. Thus, a black matrix layer having a predetermined pattern was formed.

  Next, the photosensitive coloring material is applied with a slit coater, then exposed to ultraviolet light using a photomask, cured, developed and baked in the order of R (red), G (green), and B (blue). Repeatedly, red pixels, green pixels, and blue pixels were formed in the opening area of the black matrix.

  At this time, a spacer was formed by sequentially laminating red, green and blue coloring materials in a dot pattern on the black matrix layer. The height of the laminated spacer was 3.8 μm higher than each pixel portion.

Next, the surface of the color filter layer thus formed was polished with an abrasive mainly composed of aluminum oxide. The polishing machine was an Oscar type polishing machine, and an abrasive having an average particle size of 0.05 microns was used. The polishing condition was 60 seconds at 30 rpm with a pressure of 0.02 kg / cm ² . After the polishing treatment, cleaning was performed to remove the abrasive and the polished resin component.

  Further, after washing to remove dust and the like, a transparent conductive film was formed on the color filter layer by DC sputtering. As a sputtering apparatus, a load-lock type vertical transfer type DC magnetron sputtering apparatus was used. First, after putting the substrate into the roughing vacuum chamber, the inside of the vacuum chamber is evacuated to reach a predetermined pressure, then the substrate is moved to the high vacuum chamber, and argon and oxygen are introduced into the high vacuum chamber for adjustment. After removing the pressure, the substrate was put into the sputtering chamber. In the sputtering chamber, argon (400 SCCM) and oxygen (0.2 SCCM) are introduced and the pressure is adjusted to 0.5 Pa. Using ITO (mixture of indium oxide and tin oxide (10 wt%)) as a target, an output of 6 kW is applied. Then, film formation was performed.

  Film formation was performed by a film formation method in which the substrate was passed in front of the target, and an ITO film having a thickness of 1400 mm was obtained. Thereafter, after the sputtering chamber was brought to atmospheric pressure, the substrate was taken out of the sputtering chamber, washed again, and then annealed for 1 hour in an oven at 230 ° C. in order to obtain predetermined characteristics.

Next, a SiN _x film was formed on the ITO film by plasma CVD. First, after putting a substrate into a vacuum chamber, the substrate temperature was set to 150 ° C. while evacuating. Next, after introducing SiH ₄ into 5 SCCM, NH ₃ into 25 SCCM, and H ₂ into a 250 SCCM vacuum chamber, RF with an output of 250 W was applied, and after 12 minutes, an SiN _x film with a thickness of 80 nm was obtained. This SiN _x film covered the uneven shape of the color filter layer with good step coverage. Further, this SiN _x film had good adhesion to the ITO film.

  In the color filter substrate thus obtained, the columnar spacer formed by laminating the coloring material on the black matrix layer when forming the pixels maintained the target height of 3 μm. Thereafter, a resin pattern for the MVA method for controlling the liquid crystal alignment was formed so that the resin was not formed on the tops of the columnar spacers.

In the color filter substrate formed as described above, the transparent thin film made of the SiN _x film served as an insulating layer and did not cause a vertical short circuit due to the transparent conductive film.

  When a liquid crystal display panel was prepared using the color filter substrate obtained as described above, a liquid crystal display panel having good display characteristics could be obtained without elution of ions from the color filter layer to the liquid crystal.

FIG. 3 is a cross-sectional view illustrating a configuration of a color filter substrate according to the first embodiment of the present invention. Sectional drawing which shows the structure of the color filter substrate which concerns on the 2nd Embodiment of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Transparent substrate, 2 ... Black matrix layer, 3a ... Red pixel, 3b ... Green pixel, 3c ... Blue pixel, 4 ... Columnar spacer, 5 ... Transparent thin film, 6 ... Transparent electrically conductive film.

Claims (9)

In a color filter for a liquid crystal display in which a black matrix layer and a plurality of colored layers are formed on a transparent substrate, one or more color materials constituting the colored layer are laminated on the black matrix layer. Amorphous inorganic material selected from the group consisting of SiN _x , SiO _x N _y , and SiO ₂ having a film thickness of 50 nm to 300 nm on the colored layer surface of the plurality of colors and on the columnar spacer surface A color filter for a liquid crystal display, which is coated with a transparent thin film made of 2. The color filter for a liquid crystal display according to claim 1 , wherein a height of the columnar spacer is 3 to 5 μm from a surface of the colored layer. The color filter for a liquid crystal display according to claim 1 or 2 , wherein the color filter is for IPS. Forming a black matrix layer having a predetermined pattern on a transparent substrate;
A plurality of colored layers are formed by repeating, for each color of the coloring material, applying a coloring material to the opening area divided by the black matrix layer, exposing and developing the coloring material, and the black matrix layer. A step of forming a columnar spacer by laminating one or more colored materials thereon, and forming a transparent thin film made of an amorphous inorganic material having a thickness of 50 nm to 300 nm on the colored layer surface and the columnar spacer surface A process for producing a color filter for a liquid crystal display. The method for producing a color filter for a liquid crystal display according to claim 4 , wherein the transparent thin film is formed by a plasma CVD method. The method for producing a color filter for a liquid crystal display according to claim 4 , wherein the transparent thin film is formed by a reactive sputtering method. The method for producing a color filter for a liquid crystal display according to claim 4 , wherein the transparent thin film is formed at a temperature of 200 ° C. or less. Subjected to abrasive treatment on the surface of the colored layer and the columnar spacer, to remove the residues of the surface, to any one of claims 4-7, characterized by further comprising the step of adjusting the height of the columnar spacers The manufacturing method of the color filter for liquid crystal displays of description. The method for producing a color filter for a liquid crystal display according to claim 8 , wherein the polishing is performed using an abrasive mainly composed of aluminum oxide.

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