JP2000298209A - Manufacture of color filter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance efficiency of manufacturing by reducing frequencies of exchanging photomasks in an exposure process of a photosensitive resin layer in a method for manufacturing color filters. SOLUTION: Plural times for exposure operations are carried out in an exposure process. A defective part 24 within an exposure region 21, formed with shielding light by dust 14 on a photomask 11 in the first exposure operation, is exposed in the second exposure operation by shifting the photomask 11 in this exposure operation, so as to prevent defects in a color filter from being generated and to make exchange of the photomask 11 due to the attachment of the dust 14 unnecessary.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for manufacturing a color filter for a liquid crystal display device manufactured through an exposure process.

[0002]

2. Description of the Related Art Generally, a liquid crystal display device is mounted on a personal computer, a word processor, a pachinko game console, an automobile navigation system, a small television, and the like, and the demand has been increasing in recent years. However, liquid crystal display devices are expensive and demands for cost reduction are increasing year by year.

A color filter constituting a liquid crystal display device is configured by arranging colored pixels such as red (R), green (G), and blue (B) on a transparent substrate. Is provided with a black matrix for shielding light in order to increase display contrast.

As a method of forming colored pixels of a color filter, a dyeing method, a pigment dispersion method, an electrodeposition method, an ink jet method, and the like have been proposed, but the mainstream currently depends on the pigment dispersion method.

[0005]

In the pigment dispersion method using an exposure step, when dust adheres to a photomask and the shape of the dust is transferred to a substrate in the exposure step,
The color filter may cause pixel defects such as white spots. In addition, in an inkjet method using an exposure step, adhesion of dust on a photomask may cause pixel defects such as color mixing and white spots.

In both the pigment dispersion method using the exposure step and the ink-jet method, when the above-described defect occurs, the photomask with the dust is replaced immediately with a photomask with no dust, or the white defect is removed. The parts needed to be corrected.

[0007] However, in order to replace the photomask, it is necessary to temporarily stop the production line, which causes a problem of lowering the operation rate. Further, even if the photomask is replaced, the color filter manufactured until the photomask is replaced becomes a defective product, so that the yield is reduced.

[0008] Photomasks with dust are often reproducible by cleaning. However, frequent cleaning may cause the photomask pattern to be lost.
There has been a problem that a photomask having a pattern defect cannot be used. Further, there is also a problem that a photomask in which a pattern has an electrostatic breakdown cannot be used in a conventional exposure process. Therefore, it is preferable to reduce the number of times of photomask cleaning as much as possible in view of the durability of the photomask.

In the conventional manufacturing method, photomask replacement and photomask cleaning are inevitable, and it has been difficult to reduce the number of times. If the number of photomask replacements can be reduced, the number of photomask cleanings can be reduced. Therefore, reducing the number of photomask replacements has been a very important factor in the manufacture of color filters.

An object of the present invention is to solve the above-mentioned problems, that is, to provide a method for efficiently manufacturing a color filter by reducing the number of photomask replacements.

[0011]

According to the present invention, there is provided a color filter manufacturing method, comprising: exposing a photosensitive resin layer formed on a substrate to a pattern using a photomask;
The exposure operation is performed a plurality of times while shifting the relative position of the photomask with respect to the substrate each time so as not to expose a preset unexposed area through the process.

In the present invention, by exposing a plurality of times while shifting the photomask, a region not exposed due to dust adhering to the photomask or a pattern defect of the photomask is exposed by another exposure operation. As a result, it is possible to satisfactorily expose all of the preset exposure areas, and even if the photomask has some dust attached or has a defect, a defective color filter is generated. Without having to replace the photomask.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 schematically shows a state after exposure when exposure is performed using a photomask to which dust is attached. In the figure, 11 is a photomask, 12 is a light shielding portion of the photomask, 13 is a light transmitting portion of the photomask, 14 is dust attached on the photomask, 21 is a color filter substrate,
Reference numeral 22 denotes an unexposed portion which is shielded from light by the light shielding portion 12, 23 denotes an exposed portion irradiated with light by the light transmitting portion 13, and 24 denotes dust 14
This is a defective portion that is shielded from light. The present invention is preferably applied when an unnecessary light-shielding region is generated in the light transmitting portion 13 other than the dust 14 attached to the light transmitting portion 13, for example, a pattern defect of a photomask.

In the case of the conventional manufacturing method, since the pattern exposure was completed only by the exposure operation of FIG. 1, the color filter substrate 21 was treated as a defective product by the defective portion 24.

However, in the present invention, following the exposure operation shown in FIG. 1, the same exposure operation is performed again with the position of the photomask 11 shifted. This is schematically shown in FIG.

In FIG. 2, the photomask 11 is moved by t compared to the exposure operation shown in FIG. As a result, the defective portion 24 that was shielded in the exposure operation of FIG. 1 is exposed. In the second exposure, dust 14 causes a new area 25 to be exposed.
Is shielded, but since the area has already been exposed in the first exposure operation, no defect occurs even if the area is shielded in the second exposure operation.

In the present invention, the number of exposure operations is not particularly limited as long as it is two or more. In addition, it is necessary to set the light intensity and time for each exposure so that the region 24 that is shielded from light by the dust 14 or the like is sufficiently exposed by another exposure operation. For example, if the number of exposure operations is two,
It is necessary to irradiate a sufficient amount of light in one exposure. If it is three or more times, it is sufficient that a sufficient amount of light is irradiated by the remaining operations even if the light is shielded by one of them. As the number of exposure operations increases, the overall exposure time can be set shorter, and step exposure may be performed in which exposure is performed while shifting the photomask by a small distance.

Further, in the present invention, a preset unexposed area (which is originally a light shielding section 12 in the exposure operation of FIG. 1) is used.
It is necessary to prevent the light-shielded area from being exposed by shifting the photomask. In FIG. 2, since the photomask is shifted to the right on the paper by t,
If left untouched, the area on the left side of the unexposed portion 22 on the paper will be exposed. The dust adhering to the photomask is very small, and thus the amount of the photomask displaced is about 1 to 3000 μm in the present invention. As shown in FIG. 2, the exposed portion 23 is located on the outer periphery of the color filter substrate. In such a case, the shift of the exposure region due to the shift of the photomask can be substantially ignored. However, when the light shielding portion 22 is located on the outer periphery of the color filter substrate, the light shielding region 22 is exposed to the extent that the photomask 11 is shifted from the end of the color filter substrate 21. Therefore, in such a case, it is necessary to take measures such as forming the photomask larger by an amount corresponding to the shift of the photomask.

FIG. 3 is a diagram showing an arrangement of pixels of a general color filter. The pixels 31R, 31G, and 31B are formed in a straight line in the longitudinal direction of the paper. A black matrix 34 is formed at the periphery of each pixel.

FIG. 4 shows the shape of a photomask used in the exposure step when the color filter of FIG. 3 is manufactured by the ink jet method. In the figure, 41 is a light transmitting portion, and 42 to 44 are light shielding portions. The photomask includes the pixels 31R, 3R in FIG.
1G, 31B corresponding to each pixel column,
44 are formed. After the first exposure operation, the photomask is shifted parallel to the direction 32 in which the same color pixels in FIG. 3 are continuous, and then the second exposure is performed. Alternatively, after the first exposure operation, the second exposure is performed after shifting the photomask in parallel to the pixel arrangement direction 36 in FIG. However, 36
When shifting the photomask in the direction, the shift amount is
It is assumed to be an integral multiple of the different color pixel pitch P.

FIG. 5 shows the shape of a photomask used in the exposure step when the color filter of FIG. 3 is manufactured by the pigment dispersion method. In the figure, 51 is a light-shielding portion, and 52 is a light transmitting portion. In the photomask, a light transmitting portion 52 is formed at a position corresponding to a pixel column of one color of the color filter. After the first exposure operation, the photomask is shifted in parallel to the direction 32 in which the same color pixels in FIG.
A second exposure is performed. Alternatively, after the first exposure operation, the second exposure is performed after shifting the photomask in parallel to the pixel arrangement direction 36 in FIG. However, when the photomask is shifted in the 36 directions, the shift amount is an integral multiple of three times the pixel pitch P of the different color as a unit.

The light transmitting portion and the light shielding portion of the photomask are reversed depending on whether the photosensitive resin layer to be exposed is a negative type or a positive type. Therefore, in the photomasks of FIGS. 4 and 5, the shapes of the light transmitting portion and the light shielding portion are reversed depending on the type of the photosensitive resin layer.

Hereinafter, a process of manufacturing a color filter by a method of manufacturing a color filter by an inkjet method having an exposure process will be described with reference to embodiments. The case where an exposure step is required in a method of manufacturing a color filter using an ink-jet method is mainly when an ink is applied to an ink-receiving layer by an ink-jet method to form a colored portion (colored pixel). This is in pattern exposure for forming a non-colored portion having low ink absorbency between colored portions in order to prevent color mixing of ink between the portions. That is, the photosensitive resin layer according to the present invention is an ink receiving layer in an ink jet method, and the ink absorbency changes by light irradiation.

FIG. 6 is a process chart of an embodiment of a method of manufacturing the color filter of FIG. 3 by the ink jet method. This step shows a case where a negative photosensitive resin is used for the ink receiving layer, and the ink absorbency is reduced or eliminated by exposure. The respective steps will be described below.

Step (a) A black matrix 62 is formed on a substrate 61 (FIG. 6A). As the substrate 61, a glass substrate is usually used, but a plastic substrate or the like can also be used as long as the material has necessary transparency and strength. In addition, the black matrix 62 usually has a thickness of 0.1 mm.
It can be formed by depositing a metal such as chromium by sputtering or vapor deposition and patterning it into a predetermined shape.

Step (b) An ink receiving layer 63 is formed on the entire surface of the substrate 61 (FIG. 6).
(B)). The ink receiving layer 63 is formed of a photosensitive resin. In the present embodiment, the ink receiving layer 63 has high ink absorbency when not exposed, and is cured by exposure to lose or reduce the ink absorbency. Specifically, for example, an acrylic resin, an epoxy resin, an imide resin, a cellulose derivative such as hydroxypropylcellulose, hydroxyethylcellulose, methylcellulose, and carboxymethylcellulose are preferably used. The ink receiving layer 63
The composition solution containing the resin is applied on the substrate 61 by spin coating, roll coating, bar coating, spray coating, dip coating, or the like, and if necessary, 30 to
It is formed by heat treatment in the range of 200 ° C. The thickness of the ink receiving layer 63 depends on the type, composition, or ejection amount of the ink used for pattern formation, the method of use, and the like.
About 50 μm is appropriate.

Step (c) The ink receiving layer 63 is subjected to pattern exposure using a photomask 64, and the exposed part is cured to form a non-colored part 65, and the unexposed part 66 is colored in a later step (FIG. 6 (c)). ). The distance between the photomask 64 and the substrate 61 is set to 10 to 200 μm.

In the present invention, in this step, a plurality of exposure operations are performed, and the position of the photomask 64 is set within the range of 1 to 3000 μm in each of the operations 32 or 36 in FIG.
Relative to the direction of. The exposure amount is a case where exposure is performed twice. For example, the integrated exposure amount in each exposure operation is 20 to
Set to an appropriate value within 300 mJ / cm ² .

After the exposure, if necessary, a heat treatment is performed at a temperature in the range of 20 to 300 ° C.

Step (d) Using an ink jet recording apparatus (not shown), the unexposed portion 6
The ink 67 of each color of R, G, and B is applied along a coloring pattern set in advance in FIG. 6 (FIG. 6D). At this time,
The non-colored portion 65 located between the adjacent unexposed portions repels the ink, thereby preventing color mixing of the ink between adjacent different unexposed portions. As the ink 67, a dye-based ink,
Any of the pigment systems can be used.

As the ink jet method, a bubble jet type using an electrothermal converter as an energy generating element, a piezo jet type using a piezoelectric element, or the like can be used.

Step (e) After sufficiently penetrating the ink 67 into the unexposed areas 66, drying and heat treatment (30 to 300 ° C.) are performed as necessary to form colored sections 68 (FIG. 6E). .

Step (f) If necessary, a protective layer 69 is formed (FIG. 6 (f)). As the protective layer 69, a resin composition layer of a photo-curing type, a thermosetting type, or a combination of light and heat, or an inorganic film formed by vapor deposition, sputtering, or the like can be used. In each case, it has transparency as a color filter.
Any material that can withstand a liquid crystal element manufacturing process such as a TO film forming process and an alignment film forming process can be used.

[0034]

EXAMPLE (Example 1) The color filter shown in FIG. 3 was manufactured according to the process shown in FIG. The steps will be described below.

A chromium-chromium oxide film having a thickness of 0.15 μm was formed on a glass substrate having a thickness of 1.1 mm, and was patterned to form a black matrix. in addition,
A photosensitive resin composition comprising an acrylic resin was applied to the entire surface by spin coating, and prebaked at 50 ° C. for 10 minutes to form an ink receiving layer having a thickness of 1.0 μm.

The above-mentioned ink receiving layer was subjected to pattern exposure using a photomask. The number of exposures was two, and the integrated exposure amount was 50 mJ / cm ^{2. In} the second exposure operation, the photomask was shifted by 150 μm in the direction of 32 in FIG. After the exposure, the substrate was heat-treated at 110 ° C. for 1 minute. Further, as the photomask, a photomask which was replaced with a new photomask because dust adhered on a production line of a color filter product was used.

Each of the R, G, and B inks was applied to the unexposed portions of the ink receiving layer according to a predetermined coloring pattern using an ink jet recording apparatus. After confirming that the ink had sufficiently penetrated the ink receiving layer, the colored unexposed portion was cured by heat treatment at 230 ° C. for 30 minutes to form a colored portion.

A protective layer made of a thermosetting acrylic resin and having a thickness of 1.0 μm, and an I layer having a thickness of 0.1 μm were formed on the colored portion.
A TO layer was formed. The ITO layer is a member that becomes an electrode when forming a liquid crystal element.

When the obtained color filter was observed with an optical microscope, it was confirmed that the color filter was a good color filter free from color filter defects and color mixture.

Comparative Example 1 In Example 1, except that the exposure step was performed once with an integrated exposure amount of 65 mJ / cm ² .
A color filter with an ITO layer was produced in the same manner as in Example 1.

When the obtained color filter was observed with an optical microscope, color mixing due to dust on the photomask was confirmed.

[0042]

As described above, according to the present invention,
Even with a photomask to which dust is attached or a photomask having an unnecessary light-shielding region in a light transmitting portion due to a pattern defect, a desired exposure pattern can be exposed, so that defective color filters are greatly reduced. , And the yield is improved. At the same time, the number of photomask replacements can be greatly reduced, so that the number of production line stoppages for photomask replacement can be reduced, and the line availability can be improved. Further, since the number of times the photomask is washed can be reduced, deterioration of the photomask at the time of washing can be reduced, and the cleaning cost can be reduced.
Therefore, according to the present invention, the yield and the manufacturing efficiency are significantly improved, and the manufacturing cost is reduced. Therefore, it is possible to provide an excellent color filter at a lower cost, and to reduce the price of the liquid crystal display device. It becomes possible.

[Brief description of the drawings]

FIG. 1 is a schematic view showing a first exposure operation in an exposure step of a color filter manufacturing method of the present invention.

FIG. 2 is a schematic diagram showing a second exposure operation in an exposure step of the color filter manufacturing method of the present invention.

FIG. 3 is a schematic plan view of an example of a color filter manufactured by the manufacturing method of the present invention.

FIG. 4 is a schematic plan view showing a photomask used when the color filter of FIG. 3 is manufactured by an inkjet method.

5 is a schematic plan view showing a photomask used when the color filter of FIG. 3 is manufactured by a pigment dispersion method.

FIG. 6 is a process chart showing one embodiment of a process for manufacturing a color filter by an inkjet method.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Photomask 12 Shielding part 13 Light transmission part 14 Dust 21 Color filter substrate 22 Unexposed part 23 Exposure part 24 Defect part 25 Unexposed area 31R, 31G, 31B Colored pixel 32, 36 Photomask moving direction 34 Black matrix 41 Light transmission Parts 42 to 44 Light-shielding part 51 Light-shielding part 52 Light-transmitting part 61 Substrate 62 Black matrix 63 Ink-receiving layer 64 Photomask 65 Non-colored part 66 Unexposed part 67 Ink 68 Colored part 69 Protective layer

Claims (4)

[Claims] 1. A method for manufacturing a color filter having a plurality of colored pixels, the method comprising: exposing a photosensitive resin layer formed on a substrate to a pattern by using a photomask in a pattern exposure process; A method for manufacturing a color filter, comprising performing an exposure operation a plurality of times while shifting a relative position of a photomask to a substrate each time so as not to expose an unexposed area. 2. The method of manufacturing a color filter according to claim 1, wherein the direction in which the photomask is shifted is a direction parallel or orthogonal to a direction in which the same color pixels continue in the color filter. 3. The method according to claim 1, wherein the exposure time in each exposure operation is the same. 4. The photosensitive resin layer is an ink receiving layer whose ink absorbency changes by light irradiation, and by pattern exposure, a non-colored portion having low ink absorbency and a colored portion having high ink absorbency. The method for producing a color filter according to claim 1, wherein a colored pixel is formed by forming and applying ink to the colored portion by an inkjet method.