JPH055802A - Color filter - Google Patents

Abstract

PURPOSE:To enhance light resistance, heat resistance, chemical resistance, and water resistance and to improve spectral characteristics by forming colored picture elements of the color filter by laminating the colored picture elements formed by a dyeing method and the colored picture elements formed to the same hue by a pigment dispersion method. CONSTITUTION:Signal transfer parts 12 and photodetecting parts 13 are formed on a substrate 11 and the surfaces thereof are coated with a transparent protective film 14. A transparent flattening layer 15 is formed in order to flatten the surface. Two layers of the color filters 16 consisting of the colored picture elements of respective colors are formed in correspondence to the respective photodetecting parts 13 on the flattening layer 15. The lower layer consists of the colored picture elements 17 colored by dyeing and the upper layer is constituted of the colored picture elements 18 dispersed with the pigments. The hues of the colored picture elements of the lower layer and the upper layer are the same. The characteristics inherent to the respective colored picture elements can be exhibited in this way and the colored picture elements having the arbitrary spectral characteristics are easily obtd. The colored picture elements having the characteristics of the dyes which are excellent in saturation and the pigments which are excellent in durability are obtd.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color filter, and more particularly to a color display filter used in a color liquid crystal display or a color separation filter for an image pickup device such as CCD.

[0002]

2. Description of the Related Art In recent years, color filters have been used for liquid crystal displays, viewfinders for video cameras, CCDs.
Industrial products using various color filters, which are used for color separation filters of solid-state image pickup devices, color image sensors, line sensors for color copying, and the like, are being developed.

The colored pixels of these color filters are formed by methods such as a dyeing method, a pigment dispersion method, an electrodeposition method, a vapor deposition method and a printing method. Among them, the dyeing layer and the pigment dispersion method are the main ones.

The formation of the colored pixel of the color filter by the dyeing method is formed by the photolithography technique and the dyeing technique. In the dyeing method, a colloid prepared by mixing a water-soluble polymer such as gelatin, casein or polyvinyl alcohol with a photosensitive cross-linking agent such as chromate or dichromate is used as a photosensitive material, and spin coating or the like is used. After pre-baking after forming a predetermined film thickness, the resulting photosensitive film is exposed using an exposure device such as a mask aligner, and the pattern obtained by elution of the unexposed portion by spray development with water is performed. Dye with an acid dye or a reactive dye. Next, an intermediate layer of a resin such as acrylic, urethane, or epoxy is formed as a dye-proof layer. Alternatively, a method of carrying out dye protection by a chemical reaction of tannic acid or the like may be used without using such an intermediate layer. A color filter is formed by repeating this series of steps in the same manner for the three primary colors of red (R), green (G), and blue (B).

The features of the color filter by the dyeing method can be exemplified as follows compared with the color filter by other methods. That is, (1) Since the plate is made by the photolithography method,
It is possible to form fine colored pixels (2 μm or less).

(2) A wide variety of dyes are available, and various spectral characteristics can be obtained by combining a plurality of dyes. That is, the degree of freedom with respect to the spectral characteristics is large. On the other hand, a method for forming colored pixels of a color filter by a pigment dispersion method is as follows: a colloid of a transparent photosensitive resin obtained by mixing dichromate with a water-soluble polymer such as casein, gelatin, polyvinyl alcohol, etc. A photosensitizer in which a pigment is dispersed is applied by a method such as spin coating, and is formed by a photolithography technique in the same manner as a dyeing method color filter.

The characteristics of the color filter manufactured by the pigment dispersion method can be listed as follows as compared with the color filters manufactured by other methods. That is, (1) since the plate is made by the photolithography method in the same manner as the coloring pixel of the dyeing method, the fine coloring pixel (10 μm
To the extent possible). (2) By selecting an appropriate pigment, it is superior to dyes in light fastness, that is, physical properties such as light resistance, heat resistance, chemical resistance, and water resistance. (3) There is a point that the process is simplified because a dyeing process and a dye-proofing process are not required unlike the color filter by the dyeing method.

[0008]

The colored pixel of the color filter formed by the dyeing method can easily obtain a color filter having a predetermined spectral characteristic by selecting a desired one from abundant dyes. Since it uses a dye, there are few dyes that can satisfy the physical properties required for a color filter in terms of durability such as light resistance such as color change when exposed to light, water resistance, heat resistance, chemical resistance, etc. .. In addition, when a solution containing a dye is adsorbed to the organic substance layer that becomes the base of the colored pixel, the organic base swells, and further cracks or the like may occur due to temperature change due to heating or cooling in a later step. However, there is a problem that the light transmission characteristics and the appearance are deteriorated. Also, when trying to form a high-concentration colored pixel by the dyeing method, there is a means to adsorb a large amount of dye or to make the dyeing substrate a thick film,
In these methods, the stress of the dyed substrate becomes large and cracks and the like are likely to occur. For this reason, it is difficult to obtain a high-density colored pixel by the dyeing method.

Further, in the case of forming a colored pixel by the pigment dispersion method, there are very few pigments having desired spectral characteristics while satisfying the dispersibility and transparency of the pigment with respect to the binder resin holding the pigment, and blue or Green colored pixels are limited to phthalocyanine pigments and the like. In addition, there is a problem in that the saturation of the colored pixels is low due to the light reflecting action of the pigment particles, and the brightness decreases when an attempt is made to obtain colored pixels of sufficient density.

[0010]

In order to solve the above problems, the present invention provides a colored pixel of a color filter having the same hue as the colored pixel formed by the dyeing method and the colored pixel formed by the dyeing method. The colored pixel of is formed by the pigment dispersion method, and is formed by laminating the both, and it is possible to obtain the color filter having the excellent spectral characteristics while compensating for the drawbacks of both the dyeing method and the pigment dispersion method. It is a thing.

FIG. 1 shows a sectional view of an embodiment of the color filter of the present invention. The substrate 11 is a CCD substrate, and a signal transfer portion 12 and a light receiving portion 13 are formed on the substrate, and their surfaces are covered with a transparent protective film 14. Since the surface of the element has irregularities, a transparent flattening layer 15 made of acrylic resin or the like is formed to flatten the surface.

A color filter 16 composed of colored pixels of each color is formed on the flattening layer corresponding to each light receiving portion. The colored pixels of the color filter are composed of two layers, and the lower layer is made of a dye. The colored pixel 17 is colored, and the upper layer is composed of the colored pixel 18 in which a pigment is dispersed. The hues of the colored pixels of the lower layer and the upper layer are the same, and the color filter of the present invention includes red, blue, It can be used for one, two, or all of the green colors.

When the colored pixel formed by the dyeing method and the colored pixel formed by the pigment dispersion method are laminated and provided on the substrate surface of the color filter, any colored pixel may be provided on the substrate surface side. When the light is incident, it is preferable to form colored pixels formed by the pigment dispersion method on the substrate surface side, and when light is incident from the direction opposite to the substrate surface, the pigment dispersion method is used on the side opposite the substrate surface. It is preferable to form the obtained colored pixels.

Particularly, in an on-chip type color filter provided on a substrate on which a semiconductor device or the like is formed,
A colored pixel in which a pigment having excellent light resistance is dispersed is arranged on the surface opposite to the substrate, and the light passing through the colored pixel passes through the pixel colored with a dye, which adversely affects the dyeing layer. The light exerted is greatly attenuated, and the light resistance of the whole colored pixel is higher than that of the pixel colored with the dye alone.
Greatly improved. This tendency is the same for other durability, and the pixel colored with a dye having relatively low durability is covered with the colored pixel in which the pigment is dispersed. In comparison, it can be greatly improved. In particular, it is suitable when a dye that cannot be used for a color filter is used because of its low durability even though it has satisfactory color spectral characteristics.

On the other hand, in terms of spectral characteristics, phthalocyanine green C.I. I. Pigment Green7
And azo yellow C.I. I. Due to the characteristics of the colored pixels formed by the pigment dispersion method using the 11730 (Hansaello GR) pigment, as shown in FIG. 2 (A), light from a short wavelength range of 400 nm in the visible light range to the ultraviolet range is exhibited. Therefore, the sensitivity of the photosensitive resin is lowered and it becomes difficult to form colored pixels.
Therefore, in the pigment dispersion method, in order to allow light in this region to pass therethrough, the concentration of the pigment must be lowered to obtain the spectral characteristics shown in FIG. I couldn't get it.

Therefore, by stacking a green or yellow dyeing layer on such a colored pixel, a colored pixel having a required density can be obtained. That is, in the dyeing method, the dyeing substrate pattern is formed in advance and then the dyeing is performed, so that there is no restriction from the sensitivity of the photosensitive resin, and by stacking these, a high-concentration colored pixel can be obtained.

Further, phthalocyanine-based blue C.I. used for forming colored pixels of blue (B) by a pigment dispersion method.
I. 74160 (C.I. Pigment Blu
The pigment of e15) has no problem in terms of the spectral wavelength, but it is determined that the peak value and the half-value width have a constant relationship as shown in FIG. Is difficult to change alone. Therefore, FIG. 3 (c)
In the case where the spectral characteristics as shown in (3) are required, a blue-violet acid dye (C.I. Ac.
It is possible to obtain the required spectral characteristics by stacking colored pixels formed by a dyeing method such as id Violet 49) by a dyeing method.

Further, in order to dye a dyed substrate at a predetermined density with a dye to obtain a colored pixel having a high density, it is necessary to adsorb a large amount of dye onto the dyed substrate. And the internal stress increases, and when the dyed pixel is dried, the dyed substrate, which is brittle in terms of strength, is cracked. However, by stacking the colored pixels by the pigment dispersion method, the density of the colored pixels formed by dyeing can be reduced by the amount of the density of the colored pixels by the pigment dispersion method. It is possible to reduce the size, and as a result, it is possible to prevent the occurrence of cracks.

As described above, the characteristics can be greatly improved as compared with the case of dyeing alone. In particular, it is suitable when using a dye that cannot be used for a color filter because of its low durability even though it has satisfactory color spectral characteristics.

The structure of the colored pixel is not limited to that shown in FIG.
As shown in the cross-sectional view of FIG. 4A, the entire colored pixels 22 colored with dye on the substrate 21 are covered with the colored pixels 23 in which the pigment is dispersed, or as shown in FIG. The color pixel 22 colored with a dye may be partially covered with the color pixel 23 in which the pigment is dispersed.
The method for producing a color filter of the present invention comprises forming a dyeing substrate on a substrate by a photolithography method, then immersing it in a dyeing solution to dye the dyeing substrate to form a colored pixel, and dispersing a pigment thereon. Forming colored pixels.

As another method, after forming a dyeing substrate on a substrate, a colored pixel in which a pigment is dispersed is formed on the substrate, and finally it is immersed in a dyeing solution for dyeing. In this method, since the dyeing is performed lastly, it is easy to finely adjust the spectral characteristics. However, since the colored pixel in which the pigment is dispersed is present on the dyeing substrate, the dye is difficult to adsorb from the surface, and since the adsorption of the dye starts from the edge of the pixel, it is slightly difficult to dye the inside of the pixel uniformly.

When the colored pixels are formed on the substrate side by the pigment dispersion method, the colored pixels in which the pigment is dispersed are formed on the substrate by the photolithography method, and then the dyed substrate is similarly formed thereon. Then, the dyed substrate is soaked in a dyeing solution to dye the dyed substrate to form colored pixels. In this method, since the last dyeing is performed, it is easy to finely adjust the spectral characteristics.

The thickness of each colored pixel can be set to any thickness depending on the intended use of the color filter, but a range of 0.8 μm to 2 μm is suitable.

The "hue" in the present invention means red, blue and green colors in a primary color type color filter, and includes achromatic but black. In the complementary color type color filter, it means magenta, yellow, cyan, green, or yellow, cyan, green, and also includes black.

[0025]

According to the present invention, since the colored pixels in which the dye is adsorbed and the colored pixels in which the pigment is dispersed are laminated, the characteristics possessed by the respective colored pixels are exerted, so that it is possible to easily obtain an arbitrary spectral characteristic. Thus, it is possible to obtain a colored pixel having both the characteristics of a dye having excellent saturation and the characteristics of a pigment having excellent durability such as light resistance to incident light.

[0026]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A case where the color filter of the present invention is used as a color filter of a CCD for a solid-state image pickup device will be described. The CCD device has a light receiving portion on a substrate 51 such as silicon as shown in FIG. 52 and a transfer section 53 for transferring a signal, and the surface of the element is covered with a transparent protective film 54.

Since the surface of the device has irregularities, the structure shown in FIG.
As shown in (B), a transparent photosensitive acrylic resin (FVR manufactured by Fuji Yakuhin Kogyo Co., Ltd.) is applied onto the CCD, exposed through a photomask, and then developed to form a flattening layer 55.

Then, as shown in FIG. 5 (C), a water-soluble polymer material such as casein, gelatin, or polyvinyl alcohol is irradiated with light such as ammonium dichromate to form a polymer material on the planarization layer 55. A coating film 56 of a photosensitive material mixed with a substance that promotes a reaction of being insoluble in water is formed and dried.

As shown in FIG. 5D, ultraviolet rays 58 are exposed by an ultra-high pressure mercury lamp through a photomask 57 in which a pattern of the first color corresponding to the light receiving portion is drawn.

As shown in FIG. 5 (E), the unexposed portion is eluted by spray development with water to adsorb the dye.
A dyed substrate pattern 59 is formed.

As shown in FIG. 5 (F), the substrate is immersed in a dyeing bath in which the dye of the first color is dissolved, and the pattern of the dyeing substrate is dyed to form a dyeing pattern 60. The resulting dyed layer is treated with an aqueous solution of tannic acid and potassium antimonyl tartrate or the like to prevent the dyed layer from being dyed, and then a two-colored dyed layer corresponding to the other two light-receiving parts is formed as shown in FIG. From Figure 5
The steps up to the dyeing of (F) are repeated.

On the substrate on which the colored pixels by dyeing are formed,
In the same manner as when forming a colored pixel by dyeing by applying a photosensitive material made of a water-soluble resin in which a pigment is dispersed, exposure and development with water are performed for each color to form a colored pixel by the pigment.

The above is the case where the substrate has the colored pixels by dyeing, but the case where the colored pixels made of the pigment are formed on the substrate can be manufactured in the same manner.

Example 1 A photosensitive acrylic resin (FVR manufactured by Fuji Yakuhin Kogyo Co., Ltd.) was formed on a CCD element formed on a silicon substrate having a diameter of 5 inches.
It was applied to a thickness of μm, exposed and developed to flatten the surface. A water-soluble photosensitive layer film made of casein and ammonium dichromate is formed on the flattened layer by spin coating so as to have a thickness of about 1.5 μm. Then 2kW
Of the ultra high pressure mercury lamp of FIG. In this exposure, the exposure corresponding to the red pattern was performed.

After developing the unexposed area with water, the substrate is immersed in a dyeing bath in which a red dye is dissolved to dye the photoreceptor film. After that, the dyed layer was dye-proofed with an aqueous solution of tannic acid and potassium antimonyl tartrate.

By repeating the same operation, the pattern obtained using the second mask pattern is dyed with a blue dyeing solution to form blue colored pixels, and the pattern obtained using the third mask pattern is formed. Stain with a green stain,
A green colored pixel is formed. As described above, a substrate provided with three colored pixels is obtained.

Each dyeing solution has the composition shown in Table 1.

[0038]

[Table 1]

A 1.5 μm-thick coating film was formed on the obtained colored pixels by spin coating with a water-soluble light-sensitive material containing casein and ammonium dichromate containing 5% of a red pigment shown in Table 2 dispersed therein. To do. Then 2kW
Of the ultra-high pressure mercury lamp of FIG. In this exposure, a region of the colored pixel formed by dyeing, which substantially corresponds to the red pixel, was exposed.
The layer is developed to form a pigment dispersed pattern. Since the background stain is also generated in the portions other than the pixels, ashing is performed for a short time to remove the background stain and form the pigment layer.

Similarly, instead of the red pigment, the blue pigment and the green pigment shown in Table 2 were used, and 5% of the blue pigment was used for the blue pixel.
Pixels were formed in the second pattern using the contained photosensitizer, and pixels were formed in the third pattern using the photosensitizer containing 5% of green pigment for the green pixels.

[0041]

[Table 2]

Further, for protection of the surface, a photosensitive acrylic resin is applied to the uppermost portion in a thickness of 3 μm, and after exposure and development, a protective film layer is formed to complete the process. When the color solid-state image sensor thus formed was imaged through a lens system, a good image was obtained.

When the color CCD having the color filter of this example was irradiated with light of 3000 lux from a halogen lamp for 500 hours, no change in color signal output was observed before and after the light irradiation.

On the other hand, when a color CCD having a color filter formed only by the conventional dyeing method is irradiated with light under the same conditions, 15% for blue, 5% for green, and −for red.
A 4% change in color signal output was observed. Since the signal output does not change in the CCD alone at the light irradiation amount, it is considered that in the CCD having the color filter formed only by the dyeing method, the color signal output changes due to the color change of the color filter. It was revealed that the weather resistance of the color CCD according to the example of the present invention was improved.

Example 2 A quartz glass substrate was thoroughly washed, and then a spin coating was applied to a water-soluble photosensitive liquid consisting of casein and ammonium dichromate in which 5% by weight of a red pigment was dispersed to form a photosensitive agent having a thickness of about 1.5 μm. Apply with. Then, it was selectively exposed with an ultraviolet light of a 2 kW ultra-high pressure mercury lamp using a photomask of the first pattern corresponding to the light receiving portion of the CCD element, and then developed to form a red colored pixel.

Similarly, a photosensitizer in which a blue pigment is dispersed is used to expose and develop in a second pattern to form blue colored pixels, and a photosensitive solution in which a green material is dispersed is used to form a third pattern. And exposed and developed to form green colored pixels. The pigments used are shown in Table 2.

After this, a water-soluble photosensitive liquid consisting of casein and ammonium dichromate is applied by spin coating to form a film having a thickness of about 1.5 μm, and then 2 k.
A pattern to be dyed was formed by selectively exposing with a UV light of an ultra-high pressure mercury lamp of W using a photomask of the first pattern and then developing. In this exposure, the region substantially corresponding to the red pixel in the colored pixel in which the lower layer pigment was dispersed was exposed.

After forming the pattern to be dyed, it was immersed in a dyeing bath of a red dye having the composition shown in Table 1 to dye the pattern to be dyed to form red colored pixels. Then, the colored pixels were dye-resisted with an aqueous solution of tannic acid and potassium antimonyl tartrate.

By repeating the same operation, the colored pixel dyed blue in the second pattern is formed on the colored pixel in which the blue pigment is dispersed, and the colored pixel dyed green in the third pattern is formed. A green pigment was formed on the dispersed colored pixels.

To protect the surface, a photosensitive acrylic resin was applied to the uppermost part in a thickness of 1 μm, and exposed and developed to form a protective film.

In order to protect the surface, a photosensitive acrylic resin was applied to the uppermost portion in a thickness of 1 μm, and exposed and developed to form a protective film.

The color filter substrate thus obtained is adhered to the CCD substrate with an adhesive to form a color CC.
I got D.

A good image was obtained by imaging using this color CCD.

Further, when light was irradiated for one day and night with a mercury lamp, a change in spectral characteristics was observed in a conventional color CCD having a color filter formed only by dyeing, but in the color CCD of this example. However, almost no change in spectral characteristics was observed.

[0055]

According to the present invention, the colored pixel of the color filter is formed by laminating the colored pixel formed by the dyeing method and the colored pixel of the same hue formed by the pigment dispersion method. The problems such as light resistance, heat resistance, chemical resistance, and water resistance of the colored pixel of are solved by forming a colored pixel by a pigment dispersion method, and A spectral characteristic can be combined with a colored pixel by a dyeing method to obtain a color filter having an arbitrary spectral characteristic.

[Brief description of drawings]

FIG. 1 shows an example of a cross-sectional view of a color filter of the present invention.

FIG. 2 is a diagram illustrating improvement of spectral characteristics on the short wavelength side by stacking colored pixels by dyeing.

FIG. 3 is a diagram illustrating that the half width is improved by stacking colored pixels by dyeing.

FIG. 4 is a sectional view showing another embodiment of the color filter of the invention.

FIG. 5 is a diagram showing a process of forming a color filter of the present invention on a CCD.

[Explanation of symbols]

11 ... Substrate, 12 ... Transfer part, 13 ... Light receiving part, 14 ... Protective film, 15 ... Flattening layer, 16 ... Color filter, 17 ...
Colored pixels colored with a dye, 18 ... Colored pixels dispersed with a pigment, 21 ... Dyeing substrate, 22 ... Colored pixels colored with a dye, 23 ... Colored pixel dispersed with a pigment, 51 ... Substrate, 52 ... Light receiving part, 53 ... Transfer unit, 54 ... Protective film, 55
... flattening layer, 56 ... coating film, 57 ... photomask, 58
… UV rays, 59… Dyeing substrate pattern, 60… Dyeing pattern

Claims (1)

Claim: What is claimed is: 1. In a color filter in which colored pixels are regularly formed on a substrate, the colored pixels include a colored pixel formed by dyeing with a dye and a pigment having the same hue as the dye. A color filter comprising a stack of dispersed colored pixels. 2. The color filter according to claim 1, wherein the laminated colored pixels are provided with colored pixels in which pigments are dispersed on the side on which light is incident.