JP2018005020A - Color filter and method for manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a color filter excellent in flatness and display characteristics, which reduces influences by the height of a horn-shaped part appearing on an end of a black matrix, and a method for manufacturing the color filter.SOLUTION: The color filter includes a black matrix and color pixels formed on a glass substrate and has a resist pattern cured on an upper surface of the black matrix. In a cross-sectional view, the line width of the resist pattern is smaller than the line width of the black matrix. In a plan view, the color pixels are segmented by the resist pattern. Preferably, the resist pattern is made of the same material as the black matrix or one of the color pixels, or made of a transparent resin.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a color filter in which a black matrix and colored pixels are formed on a glass substrate, and a manufacturing method thereof.

  In a display device such as a liquid crystal display device, it is a useful means to use a color filter for purposes such as color display, reflectance reduction, contrast adjustment, and spectral characteristic control. In many cases, color filters used in display devices are formed and used as pixels. As a method for forming a pixel of a color filter used in a display device, a printing method, a photolithography method, and the like can be given as methods that have been put into practical use.

  FIG. 4A is an enlarged plan view illustrating an example of a pixel of a color filter used in a liquid crystal display device. FIG. 4B is a cross-sectional view taken along the line XX of the pixel of the color filter shown in FIG. As shown in FIGS. 4A and 4B, the color filter used in the liquid crystal display device includes a black matrix 51, a colored pixel 52, an overcoat layer (not shown), and a transparent conductive film on a glass substrate 50. 54 are sequentially formed.

  As a method for manufacturing the color filter used in the liquid crystal display device, first, a black matrix 51 having an opening of a predetermined shape is formed on the glass substrate 50, and then the openings of the black matrix 51 on the glass substrate 50 are formed. A method is widely used in which the colored pixel 52 is formed in alignment with the portion, and the overcoat layer and the transparent conductive film 54 are sequentially formed.

  The black matrix 51 has a light shielding property, and the positions of the colored pixels 52 on the glass substrate are determined by the openings, so that the size of the colored pixels 52 is uniform. Further, when used in a display device, it has a function of shielding unwanted light and making an image of the display device a uniform image with no unevenness and an improved contrast.

  The black matrix 51 is formed by, for example, providing a black resist coating film on the glass substrate 50, removing unnecessary portions of the resist by pattern exposure and development on the coating film through a photomask, and remaining resist. The photolithography method for forming the black matrix 51 is employed. The thickness of the black resist is, for example, about 1.0 μm to 1.5 μm so as to obtain a necessary optical density.

  The colored pixels 52 have, for example, red, green, and blue filter functions, and are negative color resists in which pigments and other pigments are dispersed on the glass substrate 50 on which the black matrix 51 is formed. A photolithographic method is employed in which a colored pixel 52 is formed by exposing and developing the coating film through a photomask.

  The transparent conductive film 54 is formed on the glass substrate on which the black matrix 51, the colored pixels 52, and the overcoat layer are formed by, for example, sputtering using ITO (Indium Tin Oxide). The way to do it is taken.

  FIG. 5 is a schematic cross-sectional view illustrating a part of the process from the formation of the colored pixels to the overcoat layer by enlarging the vicinity of the black matrix 51.

In FIG. 5A, in order to form a green pixel after the formation of the red pixel 52 (R), the green resist 52 (G) a is applied and then exposed through a photomask 59. Here, when the thickness of the black matrix 51 is as thick as 1.0 μm to 1.5 μm, as shown in FIG. 5A, in forming the first color pixel (here, the red pixel 52 (R)), Swelling occurs on the edge of the black matrix 51. This rise is referred to as a horn portion 53, and the difference in height between the upper portion of the horn portion 53 and the upper surface of the red pixel 52 (R) (ΔH _{1 in} FIG. 5A) is referred to as a horn step. Also, the second color green resist 52 (G) a coating film of the swelling occurred on the end of the black matrix on the end of the black matrix horn step [Delta] H ₁ by the red pixel 52 (R) is present A higher excitement has occurred.

FIG. 5B shows a form after the formation of the second color green pixel 52 (G). As a result of the rising of the coating film of the green resist 52 (G) a, a horn step (ΔH ₂ ) similar to that of the red pixel (ΔH ₁ ) is formed on the end of the black matrix where no red pixel exists. A horn step (ΔH ₃ ) higher than the horn step (ΔH ₁ ) of the red pixel is formed on the end of the black matrix where the horn step ΔH ₁ due to the red pixel 52 (R) exists. .

FIG. 5C shows a form after the blue pixel 52 (B) of the third color is formed and the overcoat layer 55 is further formed. Here, for the same reason as when forming the green pixel 52 (G), the same horn as the horn step (ΔH ₃ ) of the green pixel is formed on the end of the black matrix where the horn step ΔH ₂ due to the green pixel exists. A step (ΔH ₄ ) is formed. Further, the overcoat layer 55 has a large difference in height due to the influence of the black matrix 51 and the above-described horn steps ΔH ₁ , ΔH ₂ , ΔH ₃ , and ΔH ₄ .

  If a color filter having a horn step formed on the edge of the black matrix 51 is used in a liquid crystal display device, display failure due to tilting of the liquid crystal, etc., or contrast degradation or oblique viewing due to light leakage or color mixing at the pixel periphery. The display quality will be adversely affected, such as deterioration of sex.

  As a technique for reducing the horn step, for example, a) a method in which the surface of the color filter is polished to reduce the height of the horn step before forming the overcoat layer, and b) the film thickness of the black matrix 51. (T) a method of forming low, c) or a method of forming a small overlapping width (K: see FIG. 5C) of colored pixels on the edge of the black matrix 51, d) black A method of increasing the length (P) of the tapered portion on the side surface of the matrix 51 to lower the horn step is conceivable.

  However, the above-mentioned a) the method of polishing the surface of the color filter causes a problem that the surface of the colored pixel is scratched. In addition, the method c) of reducing the overlapping width of the colored pixels has a problem in that white spots occur between the black matrix and the colored pixels due to a positional shift when the colored pixels are formed. Further, in the method d), the horn step is reduced, but the taper angle (θ) is reduced, so that the oblique visibility of the display image is deteriorated. In the next-generation high-definition display device, the taper angle (θ) needs to be maintained at 80 ° or more. As described above, there is a limit to the correspondence with the methods a) to d).

  The overcoat layer 55 reduces an adverse effect on display quality due to the occurrence of a horn step on the color filter as a flattening layer. However, even if the overcoat layer 55 is provided, the horn step itself does not disappear, but the film thickness difference of the overcoat layer locally increases due to the horn step, or the horn step portion of the colored layer becomes the overcoat layer 55. It could not be a complete measure because it might be exposed to the outside.

JP 2008-281678 A

  The present invention has been made to solve the above-described problems. In a color filter in which a black matrix and colored pixels are formed on a glass substrate, the height of a horn step generated on the edge of the black matrix is reduced. When reducing, it does not cause problems such as scratches on the surface of colored pixels due to polishing, insufficient optical density due to reduced film thickness of the black matrix, white spots between the black matrix and colored pixels, and deterioration of oblique visibility. Another object of the present invention is to provide a color filter that is excellent in flatness and display characteristics, and a method for manufacturing the same, by reducing the effect of horn steps.

In order to solve the above-mentioned problem, the invention described in claim 1
It is a color filter in which a black matrix and colored pixels are formed on a glass substrate, and includes a cured resist pattern on the upper surface of the black matrix,
In cross-sectional view, the line width of the resist pattern is smaller than the line width of the black matrix,
In the plan view, the color pixel is defined by the resist pattern, which is a color filter.

  The invention according to claim 2 is the color filter according to claim 1, wherein the resist pattern is made of the same material as that of either the black matrix or the colored pixel, or made of a transparent resin. is there.

Invention of Claim 3 is the manufacturing method of the color filter which forms a black matrix and a colored pixel on a glass substrate,
1) forming the black matrix on the glass substrate;
2) A photo-curable resist coating film is provided on the upper surface of the glass substrate on which the black matrix is formed, and a resist whose line width is smaller than the line width of the black matrix on the black matrix by exposure and development through a photomask. Forming a pattern;
3) A colored resist coating film is provided on the glass substrate on which the black matrix and the resist pattern are formed, and the colored pixels defined by the resist pattern are sequentially viewed in plan by exposure and development through a photomask. It is a manufacturing method of a color filter characterized by including the process of forming.

  According to the color filter of the present invention, a hardened resist pattern is provided on the upper surface of the black matrix, the line width of the resist pattern is smaller than the line width of the black matrix in a cross-sectional view, and the colored pixels are in the resist pattern in a plan view. As a result, there are problems such as scratches on the surface of the colored pixels due to polishing, insufficient optical density due to reduced film thickness of the black matrix, white spots between the black matrix and the colored pixels, and deterioration of oblique visibility. Without causing it, it is possible to reduce the influence of the horn step and obtain a color filter having excellent flatness and excellent display characteristics. In addition, according to the method for producing a color filter of the present invention, the color filter of the present invention can be stably produced by a normal photolithography method.

It is a schematic cross section which shows embodiment which concerns on the color filter of this invention, and its modification. It is a schematic cross section which shows a part of manufacturing process based on the manufacturing method of the color filter of this invention. It is a schematic cross section which is a part of manufacturing process based on the manufacturing method of the color filter of this invention, and shows the process following FIG. It is (a) schematic plan view and (b) schematic sectional drawing which show an example of the pixel of the conventional color filter. It is a schematic cross section which shows a part of manufacturing process of the conventional color filter.

  Hereinafter, embodiments of a color filter and a method for manufacturing the same according to the present invention will be described in detail with reference to the drawings. However, the present invention is not limited to the following embodiments without departing from the gist of the present invention. In addition, the same code | symbol is attached | subjected about the same component unless there is a reason for convenience, and the overlapping description is abbreviate | omitted. Further, in the drawings used in the following description, in order to make the features easier to understand, the portions that become the features are enlarged and shown, and the dimensional ratios of the respective constituent elements are not the same as actual.

  Fig.1 (a) is a schematic cross section which shows embodiment of the color filter of this invention. Here, the black matrix 1 is formed on the glass substrate 10, and the cured resist pattern 3 is formed on the upper surface of the black matrix 1. Further, green pixels 2 (G), red pixels 2 (R), and blue pixels 2 (B) are respectively formed in regions (openings) partitioned by the resist pattern 3. Although not shown, since the black matrix 1 is usually a lattice or stripe pattern in plan view, the resist pattern 3 on the upper surface of the black matrix 1 is similarly a lattice or stripe pattern.

  The shape of the resist pattern 3 is a trapezoidal shape as in the black matrix 1 in the cross-sectional view of FIG. 1A. However, these are not the intended trapezoidal shape, but a trapezoidal shape that normally occurs as a result of being formed by photolithography described later. Therefore, including the case of a rectangular shape. When the lengths of the bottom (longest side) of the trapezoid made of the resist pattern 3 and the black matrix 1 are the line width W of the resist pattern 3 and the line width B of the black matrix 1, respectively, there is a relationship of W <B. ing.

  Each of the green pixel 2 (G), the red pixel 2 (R), and the blue pixel 2 (B) has horn portions 2 g, 2 r, and 2 b on the side surface of the resist pattern 3. This is because when the colored resist is applied to form the green pixel 2 (G), the red pixel 2 (R), and the blue pixel 2 (B), the colored resist is resisted as a result of the relationship of W <B. This is caused by riding on the pattern 3, but its size is small, and the positions of the uppermost portions of the horn portions 2g, 2r, 2b are below the uppermost portion of the resist pattern 3, so that the respective colored pixels are in contact with each other. It is separated without doing.

  The resist for forming the resist pattern 3 is a resist that is cured by exposure (irradiation) such as ultraviolet light, laser light, or electron beam (in the following description, it will be described as a photo-curing resist). 2 (G), the red pixel 2 (R), and the blue pixel 2 (B) are preferably made of the same material or made of a transparent resin from the viewpoint of simplicity in the manufacturing process.

  When the resist forming the resist pattern 3 is a transparent resin, the refractive index of the transparent resin is such that the black matrix 1 or green pixels 2 (G), red pixels 2 (R), and blue pixels 2 ( It is desirable that the refractive index is close to any one of B) in order not to generate excessive reflected light.

  The above-described relationship of W <B, the ridges 2g, 2r, 2b on the side surfaces of the resist pattern 3 are small and low, and the resist forming the resist pattern 3 is black matrix 1, green pixel 2 (G), red pixel 2 ( R), considering that it is preferably made of the same material as that of any of the blue pixels 2 (B) or a transparent resin, and that the line width B of the black matrix 1 is usually 4.0 to 5.0 μm, In order that the resist pattern 3 and the horn portions 2g, 2r, and 2b of the colored pixels do not adversely affect the oblique visibility of the display image due to light leakage or color mixing, the line width W of the resist pattern 3 is 1.8 μm to 2 μm. It is preferably 0.0 μm.

  On the other hand, the film thickness (T) of the black matrix 1 is usually 1.0 μm to 1.5 μm, and the film thickness of the colored pixels 2 (G), 2 (R), and 2 (B) is usually 2.0 μm or less. In consideration of the fact that the film thickness of the overcoat layer 5 described later (C: see FIG. 1B) is normally 1.5 μm or less, the film thickness R of the resist pattern 3 is It is preferable that it is 1.0 micrometer-1.5 micrometers.

  FIG. 1B is a schematic cross-sectional view showing a modification of the embodiment of the color filter of the present invention, and shows a configuration in which an overcoat layer 5 is further formed on the upper surface of the form of FIG. The film thickness (C) of the overcoat layer 5 is preferably 1.5 μm or less. However, in the color filter of the present invention, a high horn step is not formed on the black matrix unlike the conventional color filter. Therefore, the difference in film thickness of the overcoat layer is not increased, or the horn step portion is not exposed to the outside of the overcoat layer 5, and the original function as the planarizing layer is effectively achieved. For this reason, the color filter excellent in flatness can be obtained. The composition for forming the overcoat layer 5 is preferably a transparent resin composition having a low foundation followability in order to improve flatness.

  Although illustration is omitted, as another modification of the embodiment of the color filter of the present invention, a transparent conductive film can be provided on the upper surface of the overcoat layer 5 in the form of FIG.

  2 and 3 are schematic cross-sectional views illustrating a part of the manufacturing process, particularly a characteristic part of the present invention, according to the method for manufacturing a color filter of the present invention. FIG. 2A shows a form in which the black matrix pattern 1 is formed on the glass substrate 10 by the same process as in the prior art.

  In FIG. 2B, in order to form a resist pattern on the upper surface of the black matrix pattern 1, a coating film of a photocurable resist 3a is provided on the form of FIG. Further, in FIG. 2C, exposure through a photomask 9a is performed to form a resist pattern. FIG. 3A shows a form after development, and a resist pattern 3 is formed on the black matrix 1.

  In FIG. 3B, in order to form a colored pixel of the first color (here, red), a coating film of red resist 2 (R) a is provided on the configuration of FIG. 3A, and a photomask 9b is interposed. Exposure. FIG. 3C shows a form after development, in which red pixels 2 (R) are formed in regions partitioned by the resist pattern 3. In the same manner, the color filter of the present invention having the form shown in FIG. 1A can be manufactured by sequentially forming green pixels and blue pixels.

  The color filter and the manufacturing method thereof of the present invention can be suitably used for a high-definition liquid crystal display device that requires high display quality, a color filter substrate that constitutes the same, and a liquid crystal display panel.

10, 50... Glass substrate 1, 51... Black matrix 52... Colored pixels 2 (R), 52 (R)... Red pixel 2 (R) a. ), 52 (G)... Green pixels 2 (G) a, 52 (G) a... Green resists 2 (B), 52 (B)... Blue pixels 2 r, 2 g, 2 b, 53. Horn part 3... Resist pattern 3 a... Photocurable resist 5, 55... Overcoat layer 9 a, 9 b, 59, photomask 54... Transparent conductive film ΔH ₁ , ΔH ₂ , ΔH ₃ , ΔH _4, horn step B, black matrix line width T, black matrix film thickness W, resist pattern line width R, resist pattern film thickness K Colored pixel overlap width P ... taper length θ ... taper angle

Claims (3)

It is a color filter in which a black matrix and colored pixels are formed on a glass substrate, and includes a cured resist pattern on the upper surface of the black matrix,
In cross-sectional view, the line width of the resist pattern is smaller than the line width of the black matrix,
The color filter, wherein the colored pixels are partitioned by the resist pattern in a plan view.   2. The color filter according to claim 1, wherein the resist pattern is made of the same material as that of either the black matrix or the colored pixel or a transparent resin. In a manufacturing method of a color filter that forms a black matrix and colored pixels on a glass substrate,
1) forming the black matrix on the glass substrate;
2) A photo-curable resist coating film is provided on the upper surface of the glass substrate on which the black matrix is formed, and a resist whose line width is smaller than the line width of the black matrix on the black matrix by exposure and development through a photomask. Forming a pattern;
3) A colored resist coating film is provided on the glass substrate on which the black matrix and the resist pattern are formed, and the colored pixels defined by the resist pattern are sequentially viewed in plan by exposure and development through a photomask. A process for producing a color filter, comprising the step of: