JPH09304763A - Color liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a color reflection type LCD(liquid crystal display) device having good display characteristics at a low cost by adding a light scattering effect to the color filter. SOLUTION: A black matrix 2 is formed on a glass substrate 1, on which a red color resin film prepared by dispersing a red (R) dye in a nonphotosensitive resin is applied and baked. A resist mask is formed on the red color resin film. Then the red color resin film is patterned. In this process, adhesion property between the resist mask and red color resin film is decreased so that the red color resin film is etched in the vertical and horizontal directions to form a red color filter 5r having a slope structure. This process is repeated for each of green (G) and blue (B) color resin films to form color filter arrays 5r, 5g, 5b of R, G, B colors each having a slope structure. The color filters 5r, 5g, 5b have an effect to scatter reflected light.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color liquid crystal display device, and more particularly to the shape of a color filter.

[0002]

2. Description of the Related Art There are roughly two types of display devices (LCD) using a liquid crystal material. One is a transmissive LCD that provides a display by providing a backlight on the back of the device.
The other is a reflection-type LCD that displays by reflecting diffused light from an indoor fluorescent lamp or the like. In particular, the reflective LCD is easy to reduce power consumption, thin, and lightweight because it does not use a backlight, and is widely used as a low-cost LCD.

In order to improve the image quality of a reflective LCD, it is important to improve the reflection / scattering efficiency of the captured peripheral light. In addition, since the amount of light that can be used is limited, it is necessary to reduce light loss as much as possible. In particular, when colorization is performed, light loss due to the color filter is unavoidable, so a more simplified device configuration is required. Therefore, until now, various studies have been conducted on the shape of the reflective electrode, the liquid crystal mode used, and the like. As a typical example, conventionally, the monthly Semiconductor
World 1995, 12, p108. A color reflective LCD as shown in FIG. 1 (written by Naofumi Kimura) is known.

FIG. 17 shows a conventional example. Structurally, an inverted stagger type thin film transistor (TFT) is formed on the glass substrate 11, and a photosensitive acrylic resin layer 25 having an irregular asperity shape is formed thereon so as to cover the entire surface of the TFT substrate. , And Al with high reflectivity on it
The structure is such that the reflective electrode 13 (which is electrically connected to the source electrode 26 of the TFT located below) using (aluminum) is formed. In the figure, 1 is a glass substrate,
2 is a black matrix, 6 is an overcoat layer, 7 is a common electrode, 12 is a drain electrode, 18 is a gate electrode,
19 is a liquid crystal layer, 27r is a red color filter, 27g
Is a green color filter, and 27b is a blue color filter.

In this structure, the reflective electrode 13 using Al is used.
Since the shape is irregular irregular shape reflecting the shape of the underlying photosensitive acrylic resin layer 25, the reflected light can be scattered at a wide angle, and the reflective electrode 13 and the TFT are formed of the photosensitive acrylic resin layer. Since the layers are separated by 25 and the reflective electrode 13 can be formed on the TFT and the wiring, there is an advantage that the utilization area of the reflected light, that is, the aperture ratio can be increased. Furthermore, if a (guest-host) liquid crystal layer 19 that does not require a polarizing plate is used as the liquid crystal material, brighter display is possible.

[0006]

However, in the above-mentioned conventional technique, a complicated process for forming the reflective electrode having an irregular asperity shape is required in addition to the TFT forming process, and the manufacturing accompanying it is required. There was a problem that an increase in cost was unavoidable.

An object of the present invention is to provide a color reflection type LCD which is low in cost and has good display characteristics.

[0008]

To achieve the above object, a color liquid crystal display device according to the present invention is a color liquid crystal display device in which two transparent insulating substrates are stuck together with a liquid crystal layer interposed therebetween. It has a light scattering effect on one transparent insulating substrate.

Further, the color filter has an inclined shape.

Further, the color filter has an uneven shape.

Further, the color filter contains light scattering particles.

[0012]

In the color reflective LCD of the present invention, the color filter for colorizing the display also serves as the light scattering plate. More specifically, the color filter has an inclined shape, the color filter has an uneven shape, or the color filter contains light scattering particles.

Since the color filter also serves as a light-scattering plate, it is possible to omit the complicated process related to the conventional formation of the reflective electrode, and it is not necessary to provide a new transparent scattering sheet or the like. The cost can be reduced significantly.

[0014]

Embodiments of the present invention will be described in detail with reference to the drawings.

(Embodiment 1) FIG. 1 is a sectional view showing a manufacturing process on a color filter substrate side. First, FIG.
As shown in FIG. 1, a black matrix 2 made of a metal film or a black organic film is formed on a glass substrate 1 (see FIG. 1).
(A)). Although the thickness of the black matrix 2 varies depending on the material used, the thickness of the black matrix 2 is set so as not to transmit light.

Next, a red color resin film 3 in which a red (R) dye is dispersed in a non-photosensitive resin is applied to a thickness of about 2 μm. Then, after baking at about 150 ° C., a resist mask 4 is formed on the red color resin film 3 (FIG. 1B).

Thereafter, the red color resin film 3 is patterned according to the formed resist mask 4. On this occasion,
By reducing the adhesion between the resist mask 4 and the red color resin film 3 and etching the red color resin film 3 from the vertical direction and the horizontal direction, the red color filter 5r having an inclined shape can be formed. (Fig. 1
(C)).

Next, the resist mask 4 is peeled off, and 200
Curing is performed at about C and the forming process of the red color filter 5r is completed.

By performing the above steps for each of the green (G) and blue (B) color resin films, the R, G, and B color filter arrays 5r, 5g, and 5b having inclined shapes are formed. Is possible (Fig. 1
(D)).

Then, after forming the overcoat layer 6 made of a transparent resin on the color filter substrate, the common electrode 7 made of a transparent conductive film is formed thereon to manufacture a color filter substrate as shown in FIG. 1 (e). .

On the other hand, the method shown in FIG.
The same color filter substrate as in (e) can be manufactured. The steps from FIG. 2A to FIG.
The same as in (a) to (c). However, FIG. 1 (c)
Unlike the case, the color filter does not need to have an inclined shape, and the color filter is formed as usual. Further, the curing temperature needs to be lower than the softening temperature of the non-photosensitive resin, so that the temperature is 200 ° C.
Try to keep it around.

After forming the color filter arrays 5r, 5g and 5b as shown in FIG. 2D as described above, the entire substrate is heated to the softening temperature of the non-photosensitive resin or higher, for example 250 ° C.
The color filter arrays 5r, 5g, and 5b of R, G, and B are melt-flowed by heating to the above temperature. After that, the overcoat layer 6 and the common electrode 7 are formed in the same manner as in FIG. 1E to manufacture a color filter substrate similar to that in FIG. 1E (FIG. 2F).

FIG. 3 is a plan view of the color filter arrays 5r, 5g, 5b formed by the manufacturing method of FIG. 1 or 2. Generally, the planar shape of the color filter is often rectangular, and as a result, the shape becomes a flat quadrangular pyramid shape. Further, if it is close to a square, it will be rather a flat hemispherical shape.

FIG. 5 shows the reflectance angle dependence of the color filter substrate measured using the measurement system shown in FIG. The dotted line in the figure is the measurement result of the color filter substrate manufactured as usual. Then, the solid line is the measurement result of the color filter substrate formed by the manufacturing method of FIG. 1 or 2. However, neither the overcoat layer 6 nor the common electrode 7 is formed. In FIG. 5, since the incident angle of light from the light source 8 in the measurement system of FIG. 4 is inclined by 30 ° from the normal direction of the substrate 9, the position of the detector 10 is set to the substrate 9
The reflectance of both color filter substrates is highest at a position of 60 ° from the horizontal direction. However, it can be seen that light is reflected at a wider angle in the solid line characteristic than in the dotted line characteristic.

Next, FIG. 6 illustrates a manufacturing process relating to the TFT substrate side and its structure. First, Al is sputtered on the glass substrate 11 by a sputtering device.
A -Si (silicon) alloy film is formed to have a thickness of about 100 nm. Next, a resist mask is formed on the Al-Si alloy film, the Al-Si alloy film is patterned into the shapes of the drain electrode 12 and the reflective electrode 13 using a phosphoric acid / nitric acid-based wet etching solution, and then the resist mask is removed. (FIG. 6A).

Next, the oxide film formed on the surfaces of the drain electrode 12 and the reflective electrode 13 in a vacuum by a chemical vapor deposition (CVD) apparatus is used as a rare gas ion such as Ar (argon) or Xe (xenon). After removing it by sputtering using P, P 3 (phosphine) gas plasma is rapidly used to deposit P (phosphorus) atoms on the drain electrode 12 and the reflective electrode 13. At this time, P atoms are selectively deposited only on the metal surface.

Next, SiH ₄ (monosidine) gas and H ₂
An a-Si (amorphous silicon) film 14 having a thickness of 500 nm is formed on the entire surface of the glass substrate 11 by using (hydrogen) gas plasma.
The film is formed to a certain extent. At this time, the drain electrode 12
Also, P atoms and Si atoms selectively deposited only on the reflective electrode 13 react with each other, and the drain electrode 1 automatically
2 and the n-type a-Si layer 15 is formed only on the reflective electrode 13. Then, using SiH ₄ gas, NH ₃ (ammonia) gas, N ₂ (nitrogen) gas, and H ₂ gas plasma, a−
A SiN (silicon nitride) film 16 is formed on the Si film 14 so as to have a thickness of about 300 nm (FIG. 6B).

Next, an Al-Si alloy film is formed on the SiN film 16 by a sputtering device so as to have a thickness of about 100 nm, and then a resist mask 17 is formed thereon to form a phosphoric acid / nitric acid-based wet etching solution. Using Al-
The Si alloy film is patterned into the shape of the gate electrode 18 (FIG. 6C).

Then, the SiN film 16, the a-Si film 14, and the n-type a-Si layer 15 are dried using CF ₄ (carbon tetrafluoride) gas and O ₂ (oxygen) gas while leaving the resist mask 17. Etching to make islands (Fig. 6)
(D)).

Next, after performing O ₂ ashing for about 1 minute, the resist mask 17 is peeled off, and a TFT substrate as shown in FIG. 6C is manufactured.

Alignment treatment (application of an alignment film and rubbing) is performed on the color filter substrate manufactured by the method of FIG. 1 or 2 and the TFT substrate manufactured by the method of FIG. 6, and then the color filter side. And the both sides of the TFT are opposed to each other with an epoxy adhesive applied to the periphery of the substrate through a spacer made of plastic particles or the like, and a guest-host liquid crystal layer 19 is injected between them and sealed with an ultraviolet curable resin. As a result, a color reflection type LCD without using a polarizing plate as shown in FIG. 7 can be manufactured.

In the color reflection type LCD shown in FIG. 7, since the color filters 5r, 5g and 5b themselves have an effect of scattering reflected light, the structure of the reflection electrode 13 may be flat.
Therefore, it is not necessary to form a reflective electrode having a complicated uneven shape on the TFT substrate side by using many steps as in the conventional art, and as a result, a significant reduction in manufacturing cost can be realized.

If the TFT shown in FIG. 6 is used as the TFT structure, the formation of the drain electrode 12 and the reflection electrode 13 can be performed at the same time, and the gate electrode 18 is used as a mask to form the TFT. Since the islands can be formed, the photolithography process can be performed only twice, and the cost can be further reduced.

In the case of a reflective LCD, the incident direction of light is mainly on the front side of the panel, that is, on the upper side of the TFT. Therefore, the TFT structure shown in FIG. 6 has a higher light-shielding effect and reduces the light OFF current. That is a great advantage. This is because when light is incident on the a-Si film 14 in the channel portion, carriers are generated by the photoelectric effect, and the resistance of the channel portion is lowered, so that the amount of current flowing during the OFF operation of the TFT, in other words, the current cutoff state increases. This is because the switching characteristics of the TFT are significantly deteriorated.

(Second Embodiment) Next, a second embodiment of the present invention will be described in detail with reference to FIGS. FIG. 8 illustrates the manufacturing process and the structure thereof on the color filter substrate side. The steps of FIGS. 8A to 8D are the same as those of FIGS. 2A to 2D. After forming the color filter arrays 20r, 20g, and 20b as shown in FIG. 8D, using a fixed roller 21 having an uneven surface with an upper limit of about 2 μm and an irregular pitch, the unevenness is obtained. Face the color filter array 20r, 20g, 2
0b is transferred (FIG. 8 (e)).

After that, the overcoat layer 6 and the common electrode 7 are formed in the same manner as in FIG. 1E, and the color filter substrate as shown in FIG. 8F is manufactured.

As another method, a color filter substrate similar to that shown in FIG. 8 can be manufactured by the method shown in FIG. The steps of FIGS. 9A to 9D are the same as those of FIGS. 2A to 2D. After forming the color filter arrays 20r, 20g, and 20b as shown in FIG. 9D, the color filter arrays 20r and 20g are provided with a metal plate 22 having an irregular surface with an upper limit of about 2 μm and an irregular pitch. , 20b, and the uneven surface is transferred onto the color filter arrays 20r, 20g, 20b (FIG. 9 (e)).

After that, the overcoat layer 6 and the common electrode 7 are formed in the same manner as in FIG. 1E, and the color filter substrate as shown in FIG. 9F can be manufactured.

FIG. 10 shows a color filter array 20r, 20g, 20 formed by the method of FIG. 8 or FIG.
It is a top view of b. Due to the mold having the irregular uneven surface, the surface shapes of the color filters 20r, 20g, 20b also have the irregular uneven shape. FIG.
3 shows the reflectance angle dependence of the color filter substrate manufactured in FIG. The dotted line in the figure is the measurement result of the color filter substrate manufactured as usual, and the solid line is the measurement result of the color filter substrate manufactured by the method of FIG. 8 or 9. However, the overcoat layer 6 and the common electrode 7 are not formed. Also in this figure, as in FIG. 5, the reflectance is highest at a position of 60 ° from the horizontal direction of the substrate. However, it can be seen that the emission angle of the reflected light is wider than that of the color filter substrate manufactured by the method of FIG. 1 or 2.

A color filter substrate manufactured by the method of FIG. 8 or 9 and a T manufactured by the method of FIG.
The FT substrate and the FT substrate are laminated in the same process as in FIG. 7 to manufacture a color reflection type LCD without using a polarizing plate as shown in FIG. The color reflective LCD shown in FIG. 12 also has the same effect as the color reflective LCD shown in FIG.

(Third Embodiment) Next, a third embodiment of the present invention will be described in detail with reference to FIGS. 13 to 16. FIG.
3 describes the manufacturing process and its structure on the color filter substrate side. First, the black matrix 2 is formed on the glass substrate 1 (FIG. 13A).

Next, a red color resin film 23 having a high light refractive index and containing light-scattering particles colored in red and having a particle size of 1 μm or less is applied to a thickness of about 2 μm. Then, after baking at about 150 ° C., a resist mask 4 is formed on the red color resin film 13 (FIG. 13B).

Next, the red color resin film 23 is patterned according to the formed resist mask 4 (FIG. 13).
(C)) The resist mask 4 is peeled off, and the resist mask 4 is cured at about 200 ° C. to complete the step of forming the red color filter 24r. By repeating the above steps for the green and blue color filters containing the green and blue light scattering particles, the R, G, and B color filter arrays 24r, 24g, and 24b can be formed (FIG. 13 (d)).

After that, the overcoat layer 6 and the common electrode 7 are formed in the same manner as in FIG. 7E, and the color filter substrate as shown in FIG. 13E can be manufactured.

FIG. 14 is a plan view of the color filter arrays 24r, 24g, 24b formed by the method of FIG. Further, FIG. 15 shows the reflectance angle dependence of the manufactured color filter substrate. The dotted line in the figure is the measurement result of the color filter substrate manufactured as usual, and the solid line is the measurement result of the color filter substrate manufactured by the method of FIG. However, the overcoat layer 6 and the common electrode 7 are not formed. Also in this case, the reflectance is highest at a position of 60 ° from the horizontal direction of the substrate as in FIG. However, it can be seen that the emission angle of the reflected light is wider than that of the color filter substrate manufactured by the method of FIG. 8 or 9. This is because the light scattering particles improve the scattering characteristics of the reflected light, and at the same time, the inclusion of the light scattering particles causes the color filters 24r, 24g,
This is probably because the uneven shape is added to 24b itself.

In the present embodiment, in order to prevent the deterioration of chromaticity characteristics due to the decrease of the dye concentration in the color resin film due to the inclusion of the light scattering particles, the color filters 24r, 24g and 24b of R, G and B are respectively provided. , R, G, B were included in the light-scattering particles. However, in particular, colorless light-scattering particles may be used as long as there is no problem in chromaticity characteristics and the like. The shape of the light-scattering particles is not limited, and may be spherical, triangular pyramid, quadrangular pyramid, or a polyhedron more than that, as long as the light-scattering property is high.

The color filter substrate manufactured by the method of FIG. 13 and the TFT substrate manufactured by the method of FIG. 6 are bonded together by the same process as in FIG.
It is possible to manufacture a color reflective LCD without using a polarizing plate as shown in FIG. Color reflective LCD shown in FIG.
Also has the same effect as the color reflection type LCD of FIG.

In the embodiments of the present invention described above, an example in which a TFT is used as a switching element has been described as a method for operating liquid crystal molecules, but the method is not limited to this, and a thin film diode (TFD) or a metal is used. / Insulating film / Metal (MIM) element may be used, or the same effect as that of the present invention may be obtained by simple matrix driving without using an active element. Furthermore, when the color filter according to the present invention is used in a transmissive LCD, there is a side effect of improving the viewing angle characteristics. Also, regarding the electrode material,
A material other than the Al alloy may be used as long as the material has high reflectance and good contact characteristics with the impurity semiconductor layer.

[0049]

As described above, according to the present invention, a significant reduction in manufacturing cost can be realized. The reason is that by adding a light scattering effect to the color filter,
This is because the TFT structure can be greatly simplified, and as a result, it is possible to omit the complicated process related to the formation of the reflective electrode having the concavo-convex shape as in the related art.

According to the present invention, the viewing angle characteristics can be improved. The reason is that the color filter itself can give an angle to the emitted light.

Further, according to the present invention, it is possible to suppress deterioration of image quality due to wiring signal delay over a large area.
The reason is that a low resistance Al-based material can be used for the drain electrode as well as the reflective electrode. Also,
This is because when the TFT structure is a forward stagger type structure, the Al-based material can be used for the gate electrode relatively easily.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a color filter of the present invention and a manufacturing process thereof.

FIG. 2 is a cross-sectional view showing another manufacturing process of the color filter of the present invention.

FIG. 3 is a plan view of a color filter of the present invention.

FIG. 4 is a diagram showing a measurement system of reflectance angle dependence.

FIG. 5 is a diagram showing the reflectance angle dependence of the color filter of the present invention.

FIG. 6 is a cross-sectional view showing a TFT of the present invention and a manufacturing process thereof.

FIG. 7 is a sectional view of a color reflective LCD including a color filter substrate and a TFT substrate of the present invention.

FIG. 8 is a cross-sectional view showing another color filter of the present invention and the manufacturing process thereof.

FIG. 9 is a cross-sectional view showing another color filter and another manufacturing process of the present invention.

FIG. 10 is a plan view of another color filter of the present invention.

FIG. 11 is a diagram showing the reflectance angle dependence of another color filter of the present invention.

FIG. 12 is a cross-sectional view of another color reflective LCD including the TFT substrate of the present invention and another color filter substrate.

FIG. 13 is a cross-sectional view showing another color filter of the present invention and the manufacturing process thereof.

FIG. 14 is a plan view of another color filter of the present invention.

FIG. 15 is a diagram showing the reflectance angle dependence of another color filter of the present invention.

FIG. 16 is a cross-sectional view of another color reflective LCD including the TFT substrate of the present invention and another color filter substrate.

FIG. 17 is a sectional view of a conventional color reflective LCD.

[Explanation of symbols]

 1 Glass Substrate 2 Black Matrix 3 Color Resin Film 4 Resist Mask 5r Red Color Filter 5g Green Color Filter 5b Blue Color Filter 6 Overcoat Layer 7 Common Electrode 8 Light Source 9 Color Filter Substrate 10 Detector 11 Glass Substrate 12 Drain Electrode 13 Reflective Electrode 14 a-Si film 15 n-type a-Si layer 16 SiN film 17 resist mask 18 gate electrode 19 liquid crystal layer 20r red color filter 20g green color filter 20b blue color filter 21 uneven transfer roller 22 uneven transfer metal plate 23 Light-scattering particle-containing color resin film 24r Red color filter 24g Green color filter 24b Blue color filter 25 Photosensitive acrylic resin layer 26 Source electrode 27r Red color Filter 27g green color filter 27b blue color filter

Claims (4)

[Claims] 1. A color liquid crystal display device in which two transparent insulating substrates are bonded to each other with a liquid crystal layer sandwiched therebetween, and a color filter having a light scattering effect is provided on one transparent insulating substrate. Color liquid crystal display device. 2. The color liquid crystal display device according to claim 1, wherein the color filter has an inclined shape. 3. The color liquid crystal display device according to claim 1, wherein the color filter has an uneven shape. 4. The color liquid crystal display device according to claim 1, wherein the color filter contains light scattering particles.