JP2000089214A - Liquid crystal display device and method of manufacturing the same - Google Patents

Abstract

(57) Abstract: In a facing source structure in which a source bus line and a gate bus line are provided on separate substrates, a black matrix layer having a sufficient light shielding property is formed on a color filter substrate, and the portion protrudes. To prevent the alignment disorder of the liquid crystal layer from occurring. SOLUTION: A CF layer 102, 10 on a transparent substrate 101 is provided.
3, 104 and the source bus line 105 are formed, and CF
The BM layer 106 is formed by back exposure using the layer 102 as a mask. The exposure is adjusted so that the thickness of the BM layer 106 on the source bus line is equal to or less than the thickness of the CF layer, preferably equal to or more than 400 nm. When the BM layer 106 partially overlaps the end of the CF layer, the thickness of the overlap is C
The thickness should be equal to or less than the thickness of the central part of the F layer. On the other substrate side, a picture element electrode, a gate bus line, a thin film transistor, a reference line, and the like are provided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to an OA (Official)
e Automation) equipment and AV (Audio)
The present invention relates to a liquid crystal display element capable of color display used for a display such as a visual device and a method for manufacturing the same.

[0002]

2. Description of the Related Art FIG. 2A is a perspective view showing a schematic structure of one substrate in a conventional liquid crystal display device.
(B) is a sectional view of a portion of the liquid crystal display device corresponding to the line AA '.

This liquid crystal display device comprises a pair of substrates 21 and 2
2 are arranged facing each other with a predetermined gap, and a liquid crystal layer 23 is sandwiched between both substrates. On one substrate 21, a source bus line 24 and a gate bus line 25 are arranged so as to cross each other (here, orthogonal), and a switching element 26 such as a thin film transistor (TFT) is provided near the intersection of the two. Further, the switching element 2
6 and a pixel electrode 27 to which a voltage for controlling the alignment state of the liquid crystal layer 23 is applied.

A substrate (color filter (CF) substrate) 22 facing this substrate has red (R), green (G) and blue (B) colors corresponding to the picture element electrodes provided on the substrate 21. A filter (CF) layer 28 is provided, on which ITO
A counter electrode 29 made of (Indium Tin Oxide) is provided. A BM layer 211 made of a metal film, a resin material, or the like is provided to shield the space between the color filter layers 28 from light.

Hereinafter, a conventional method for manufacturing a CF substrate will be described with reference to FIGS. Note that FIG.
Is a flowchart of a manufacturing process of the CF substrate, and FIG. 4 is a diagram showing the manufacturing process.

First, as shown in FIG. 3 and FIG.
A resin film (dry film) in which a red pigment is dispersed is laminated on a glass substrate 31 and exposed, developed, and baked to form a pattern of a red CF layer 32 (R). A dry film in which a green pigment is dispersed is laminated thereon and exposed, developed and baked to obtain a green CF.
The layer 32 (G) is patterned, and similarly, the blue CF layer 32 (B) is patterned to form three color CF layers. In this step, instead of laminating a dry film, a method has been proposed in which a photosensitive resin material in which a pigment is dispersed is entirely applied by spin coating.

[0007] Next, as shown in FIG.
(Indium Tin Oxide) is formed to form a counter electrode 33. Thereafter, as shown in FIG. 4C, a dry film in which carbon is dispersed is laminated, and exposure is performed from the back surface using the CF layer as a mask. , Development and baking to form a BM layer 34 made of a photosensitive resin material. Thus, a CF substrate as shown in FIG. 4D is manufactured.

On the other hand, a BM layer using a metal film has been conventionally known, and this manufacturing method will be described with reference to FIGS. FIG. 5 is a flowchart of a manufacturing process of the CF substrate, and FIG. 6 is a diagram showing the manufacturing process.

First, as shown in FIGS. 5 and 6 (a),
A metal film to be the BM layer 44 is formed. This film formation is generally performed by a sputtering method. Then, the BM layer 44 is formed through a photolithography process, an etching process, and a cleaning process.

[0010] Next, as shown in FIG.
The F layers 42 (R), 42 (B), 42 (G) are formed.
The CF layer is formed by arranging a photosensitive resin material by lamination of a dry film or spin coating as described above, and then performing exposure, development, and baking to form each color.

[0011] Thereafter, as shown in FIG.
Is formed to form a counter electrode 33. As a result, FIG.
A CF substrate as shown in FIG.

In either method, the counter electrode is generally formed on the entire surface.

In this liquid crystal display device, a signal is sequentially applied to bus lines 24 and 25 arranged on one substrate 21 to switch a TFT 26 located near the intersection of the two, and a signal voltage is applied to a pixel electrode 27. Write. Then, the alignment state of the liquid crystal layer 23 sandwiched between the pixel electrodes 27 and the counter electrode 29 disposed on the CF substrate 22 is controlled by the potential difference between the two substrates. Thereby, display is performed by controlling light shielding and transmission.

In the structure of the conventional liquid crystal display device, components such as a switching element for driving a picture element electrode, a gate bus line, and a source bus line are arranged on one substrate. In order to electrically separate these conductive films and functional films, the conductive films and the functional films are arranged on substantially the same plane at predetermined intervals, so that no voltage can be applied to the liquid crystal layer in these gaps, and light-shielding and light-transmitting properties cannot be obtained. Cannot control light. Therefore, it is necessary to provide a BM layer on the CF substrate. In this liquid crystal display device, the source bus line is arranged in a portion facing the BM layer, so that the metal film also functions as a light shielding layer. Therefore, the portion that is shielded by the BM layer made of a photosensitive resin material or the like is reduced.

However, in the structure of the conventional liquid crystal display device, since the gate bus lines and the source bus lines are arranged on the same substrate via the insulating film, an electric short circuit occurs between the two and a manufacturing problem. This has been a factor in lowering the yield.

Therefore, in order to solve this problem, for example, (1) J.I. F. Clerc et al. New
Electronics Architectures
for Liquid Crystal Displa
ys Based on Thin Film Tra
nsistors. Japan Display ''
86, (2) Kenichi Oki et al. Full-color liquid crystal display using new active matrix Television Society Technical Report ITEJ Technical Report
t Vol. 11 No. 27, pp. 73-78,
(3) Kenichi Oki et al. Active matrix display
JP-A-62-133478 discloses that a switching element and a gate bus line are provided on a first glass substrate,
A structure in which a source bus line is provided on a second glass substrate is disclosed.

FIG. 7 shows a schematic configuration of this structure (hereinafter, referred to as a facing source structure).

In this liquid crystal display device, a gate bus line 501, a reference line 503 for applying a reference potential to a liquid crystal layer, a picture element electrode 504, and a switching element 505 are arranged on a first glass substrate. A source bus line 502 is arranged above. The two substrates are opposed to each other with a certain gap therebetween, and a liquid crystal layer is sandwiched between the two substrates. In the structure of the liquid crystal display device, since there is no intersection of the gate bus line 501 and the source bus line 502 on the first glass substrate, it is possible to prevent an electrical short circuit between the two and improve the production yield. it can. Further, since the intersection does not exist, the influence of the capacitive coupling on the gate bus line and the source bus line is small, which is effective for signal delay.

[0019]

In the above-mentioned liquid crystal display device having the opposed source structure shown in FIG. 7, when performing color display, a CF layer which selectively transmits each wavelength is formed on a second glass substrate. Must be formed into a CF substrate.

In particular, in the liquid crystal display device having the opposed source structure, the source bus line is provided on the same side of the substrate as the CF layer, and is provided in a portion facing the BM layer as in the general liquid crystal display device shown in FIG. There is no source bus line made of a metal film. Therefore, it is more important to form a BM layer made of a photosensitive resin material or the like to shield light.

However, when a step is formed on the surface of the CF substrate due to the BM layer, the alignment state of the liquid crystal layer is disturbed at that portion, causing a display problem. Therefore, in order to maintain good display quality, the thickness of the BM layer is very important.

The present invention has been made to solve such a problem, and in an opposed source structure capable of improving the production yield, the liquid crystal layer has an alignment state of the BM layer while ensuring a sufficient light shielding property. It is an object of the present invention to provide a liquid crystal display device capable of obtaining good display quality while preventing disturbance and a method for manufacturing the same.

[0023]

A liquid crystal display device according to the present invention comprises a plurality of picture element electrodes provided in a matrix on one of a pair of substrates opposed to each other with a liquid crystal layer interposed therebetween. A plurality of gate bus lines provided in parallel with each other through the vicinity of the pixel electrode; a switching element for selectively driving the pixel electrode; and a switching element provided in parallel with the gate bus line, A reference line for providing a reference potential, a color filter layer of a plurality of colors provided on the other of the pair of substrates corresponding to each of the picture element regions, and a gate bus on the color filter layer. A liquid crystal display device having a plurality of source bus lines provided so as to intersect a line, wherein a black matrix made of a photosensitive resin material partially overlaps the source bus lines and is provided between the color filter layers. Scan layer is provided, the thickness of the black matrix layer on the source bus lines is not more than the thickness of the color filter layer, the object is achieved.

Preferably, the thickness of the black matrix layer on the source bus line is 400 nm or more.

The end of the color filter layer may be tapered, and the black matrix layer may partially overlap the slope.

Preferably, the thickness of the overlap between the black matrix layer and the color filter layer is equal to or less than the thickness of the central portion of the color filter layer.

According to the method of manufacturing a liquid crystal display device of the present invention, a plurality of picture element electrodes provided in a matrix are formed on one of a pair of substrates opposed to each other with a liquid crystal layer interposed therebetween. A plurality of gate bus lines provided in parallel with each other through the vicinity of the pixel electrode, a switching element for selectively driving the pixel electrode, and a switching element provided in parallel with the gate bus line to apply a reference potential to the switching element. A reference line to be given, and a color filter layer of a plurality of colors provided for each of the picture element regions on the other substrate of the pair of substrates,
A plurality of source bus lines provided on the color filter layer so as to intersect the gate bus lines; and a black matrix layer provided between the color filter layers so as to partially overlap the source bus lines. A method of manufacturing a liquid crystal display device, comprising: forming a plurality of color filter layers on a transparent substrate; and forming a source bus line made of a transparent conductive film on the color filter layers. A black matrix material made of a photosensitive resin is arranged on a transparent substrate, and the black matrix layer is formed such that the thickness of the black matrix layer on the source bus line is equal to or less than the thickness of the color filter layer, and equal to or greater than 400 nm. Forming a pattern by exposing with a predetermined exposure amount from the substrate side, whereby the object is achieved.

Hereinafter, the operation of the present invention will be described.

According to the present invention, one substrate is provided with a pixel electrode, a gate bus line, a switching element, a reference line and the like, and the other substrate is provided with a CF layer, a source bus line and a B bus.
With the opposed source structure in which the M layer is arranged, it is possible to prevent a defect from occurring due to an electric short circuit between the gate bus line and the source bus line. Further, since there is no intersection between the gate bus line and the source bus line, the influence of capacitive coupling on the gate bus line and the source bus line is small, and the signal delay can be reduced.

Since the BM layers are provided between the CF layers, the recesses between the CF layers are filled to flatten the surface of the CF substrate and to prevent light leakage at a portion that does not contribute to display. be able to. Since the thickness of the BM layer portion overlapping the source bus line is equal to or less than the thickness of the CF layer,
The pattern edge of the layer does not protrude, so that a step does not occur on the surface, and the alignment disorder of the liquid crystal layer can be prevented.

When the thickness of the BM layer is 400 nm or more, the light transmittance of the BM layer made of a photosensitive resin can be 0.5% or more as shown in Table 1 in the embodiment described later. A very good contrast ratio is obtained as a liquid crystal display device.

The BM layer may partially overlap the end of the CF layer. In this case, if the thickness of the overlap (the sum of the thickness of the BM layer and the thickness of the CF layer in the overlap portion) is equal to or less than the thickness of the CF layer central portion, as shown in FIG. In addition, the pattern edge of the BM layer does not protrude at the overlapping portion, so that a step does not occur on the substrate surface, and it is possible to prevent the alignment disorder of the liquid crystal layer.

For example, when the end of the CF layer has a tapered shape, even if the BM layer partially overlaps the end of the CF layer, if the overlap between them is thinner than the thickness of the center of the CF layer, the pattern of the BM layer is reduced. No edges protrude.

In the method of manufacturing a liquid crystal display device according to the present invention, after forming a source bus line composed of a CF layer and a transparent conductive film, a BM material composed of a photosensitive resin is applied or laminated on a substrate. Place and expose from the substrate side. Thereby, the BM material is exposed using the CF layer as a mask, and a BM layer is formed between the CF layers. At this time, B
By adjusting the thickness and exposure of the M material, the thickness of the BM layer on the source bus line is equal to or less than the thickness of the CF layer, and
It can be controlled to be 400 nm or more.

[0035]

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

FIG. 1A is a sectional view showing a schematic structure of a CF substrate in a liquid crystal display device according to an embodiment of the present invention.

This CF substrate has a CF substrate 102 of each color of red (R), green (G) and blue (B) on a transparent substrate 101.
Reference numerals 03 and 104 are provided corresponding to the picture element regions, and a source bus line 104 made of a transparent conductive film is provided thereon. The BM layer 106 is provided between the CF layers so as to partially overlap the ends.

The CF substrate includes a matrix of picture element electrodes 504 as shown in FIG. 7, a gate bus line 501 provided in a direction crossing the source bus lines, and a switching element for selectively driving the picture element electrodes. (TFT) 50
5. A liquid crystal display device is formed by bonding the liquid crystal layer to a first substrate provided with a reference line 503 for providing a reference potential to the switching element and sandwiching a liquid crystal layer between the two substrates.

This liquid crystal display device can be manufactured, for example, as follows.

First, a resin film (dry film) in which a red pigment is dispersed is laminated on a transparent substrate 101 such as a glass substrate, and exposed, developed and baked to obtain a red (R) film.
Is formed in a pattern corresponding to the red picture element region.

A dry film in which a green pigment is dispersed is laminated thereon and exposed, developed and baked to form a green (G) CF layer 103 corresponding to a green picture element region.

Similarly, a blue (B) CF layer 104 is patterned to form a three-color CF layer. In this step and in the BM layer forming step described later, instead of laminating a dry film, a photosensitive resin material in which a pigment is dispersed may be applied over the entire surface by spin coating. Further, the order of forming each color at this time may be another order.

In this embodiment, a CF layer of each color was formed using a transer film manufactured by Fuji Photo Film Co., Ltd. as a dry film. Initial dry film thickness is 2μm
The film thickness after baking or curing treatment is 1.7 μm to 1.8 μm.
m.

Next, an ITO film is formed by a sputtering method, and a pattern is formed by a photolithography process using a resist. Then, the source bus line 105 is formed by performing etching using the second iron chloride.

Thereafter, a dry film in which carbon is dispersed is laminated, exposure is performed from the back surface (substrate side) using the CF layer as a mask, development and baking are performed to form a BM layer 106 made of a photosensitive resin material. At this time, the BM material remains on the tapered portion of the edge of the CF layer due to the light wraparound and is formed so as to fill the space between the patterns of the CF layer and the BM layer, so that the substrate surface is flattened.

In the present embodiment, a 1.5 μm-thick film was initially formed to a desired film thickness by adjusting the exposure amount, using a transer film manufactured by Fuji Photo Film Co., Ltd. as a dry film.

In this CF substrate, the BM layer 106 is on the same substrate side as the source bus line 105 made of ITO, and the source bus line made of a metal film is formed in a portion facing the BM layer as shown in FIG. Does not exist. Therefore, it is necessary to make the light shielding property of the BM layer sufficient.

Table 1 below shows the relationship among the back exposure amount, the remaining film amount, and the transmittance of the BM layer.

[0049]

[Table 1]

The exposure amount is measured by an integrating luminometer,
The transmittance was measured with a spectrophotometer manufactured by Olympus. Further, the remaining film amount was measured at a portion of the BM layer 106 overlapping the source bus line.

From the results shown in Table 1, it can be seen that the residual film amount increases and the transmittance decreases as the back surface exposure amount increases.

Here, in order to obtain a good contrast ratio as a liquid crystal display device, it is desirable that the light transmittance of the BM layer be approximately 1% or less. B used in this embodiment
For the M material, the measured value of the light transmittance was about 1% when the thickness of the BM layer was 350 nm to 370 nm. Therefore, by setting the backside exposure amount to 15 mJ / cm ² or more, the thickness of the BM layer becomes 3
It is understood that it is desirable to set the thickness to 70 nm or more.

Furthermore, in order to further improve the contrast ratio and reliably shield the leakage light, the transmittance of the BM layer is desirably 0.5% or less. Therefore, in this BM material, the back surface exposure amount is set to 20 mJ / cm ² or more,
It is understood that it is desirable to set the thickness of the layer to 400 nm or more.

Although the amount of residual film increases when the exposure amount from the back surface increases, the over-exposure causes the residual film amount to increase as shown in FIG.
As shown in (b), the BM layer 108 is formed on the CF layer in the picture element region.
Remains, or a BM layer portion 107 having a thickness exceeding the thickness of the CF layer is formed in an overlapping portion with the CF layer. If the BM layer 108 remains on the CF layer or the BM layer portion 107 exceeds the thickness of the CF layer as described above, the pattern edge causes disorder in the orientation of the liquid crystal layer, resulting in display problems.

Therefore, the thickness of the BM layer 106 is set to be equal to or less than the thickness of the CF layer, and when the BM layer 106 partially overlaps the CF layer, the thickness of the overlap exceeds the thickness of the CF layer central portion. It is desirable to adjust the exposure so that there is no exposure. From the results shown in Table 1 above, in the BM material used in this embodiment, it is desirable that the back surface exposure amount is 130 mJ / cm ² or less and the remaining film amount is not more than the CF layer thickness.

In this embodiment, the optimum exposure amount is 20 m
Exposure was performed at J / cm ² to form a BM layer 106 having a thickness of 406 nm.

The thus obtained CF substrate and the first substrate provided with the picture element electrodes, the gate bus lines, the switching elements, the reference lines and the like by a known method intersect the gate bus lines and the source bus lines. (Here orthogonal)
Then, a liquid crystal is injected into a gap between both substrates to manufacture a liquid crystal display device.

According to this liquid crystal display device, the contrast ratio can be improved by preventing light leakage, and good display characteristics can be obtained without causing disturbance in the alignment of the liquid crystal.

[0059]

As described above in detail, according to the present invention, in the opposed source structure capable of improving the production yield, it is possible to secure a sufficient light shielding property in the BM layer and improve the contrast ratio. it can. Furthermore, since the CF substrate can be flattened by filling the spaces between the CF layers with the BM layer, and since there is no projection due to the pattern edge of the BM layer on the surface of the CF substrate, it is possible to prevent the alignment disorder of the liquid crystal. As a result, a liquid crystal display device having excellent display quality can be realized.

In particular, by setting the thickness of the BM layer to 400 nm or more, the light transmittance of the BM layer made of a photosensitive resin can be 0.5% or more, so that a very good contrast as a liquid crystal display device can be obtained. The ratio is obtained.

Further, according to the present invention, the BM layer can be formed to have a desired thickness by controlling the exposure amount of the back surface exposure, so that a liquid crystal display device having excellent display quality can be manufactured at a low cost. It can be manufactured without an increase.

[Brief description of the drawings]

FIG. 1 is a diagram showing a schematic configuration of a CF substrate in a liquid crystal display device according to an embodiment of the present invention.

FIG. 2 is a diagram showing a schematic configuration of a conventional general liquid crystal display device.

FIG. 3 is a flowchart showing a conventional CF substrate manufacturing process.

FIG. 4 is a diagram showing a conventional manufacturing process of a CF substrate.

FIG. 5 is a flowchart showing a process for manufacturing another conventional CF substrate.

FIG. 6 is a diagram showing a manufacturing process of another conventional CF substrate.

FIG. 7 is a diagram showing a schematic configuration of a conventional liquid crystal display device having a facing source structure.

[Explanation of symbols]

 Reference Signs List 101 Transparent substrate 102, 103, 104 CF layer 105 Source bus line 106 BM layer

Claims (5)

[Claims] 1. A plurality of picture element electrodes provided in a matrix form on one of a pair of substrates arranged opposite each other with a liquid crystal layer interposed therebetween, and a plurality of picture element electrodes passing through the vicinity of the picture element electrodes and A plurality of gate bus lines provided in parallel, a switching element for selectively driving the picture element electrode, and a reference line provided in parallel with the gate bus line and providing a reference potential to the switching element; A plurality of color filter layers provided on the other of the pair of substrates corresponding to the respective picture element regions; and a plurality of sources provided on the color filter layers so as to intersect with the gate bus lines. A liquid crystal display device having a bus line, wherein a black matrix layer made of a photosensitive resin material is provided between the color filter layers so as to partially overlap the source bus line; The liquid crystal display device the thickness of the black matrix layer is equal to or less than the thickness of the color filter layer. 2. The liquid crystal display device according to claim 1, wherein the thickness of the black matrix layer on the source bus line is 400 nm or more. 3. The liquid crystal display device according to claim 1, wherein an end of the color filter layer is inclined in a tapered shape, and the black matrix layer partially overlaps the inclined portion. 4. The liquid crystal display device according to claim 3, wherein an overlapping thickness of the black matrix layer and the color filter layer is equal to or less than a thickness of a central portion of the color filter layer. 5. A plurality of pixel electrodes provided in a matrix on one of a pair of substrates opposed to each other with a liquid crystal layer interposed therebetween, and a plurality of pixel electrodes passing through the vicinity of the pixel electrodes and A plurality of gate bus lines provided in parallel, a switching element for selectively driving the pixel electrode, and a reference line provided in parallel with the gate bus line and providing a reference potential to the switching element; A plurality of color filter layers provided on the other of the pair of substrates corresponding to the respective picture element regions; and a plurality of sources provided on the color filter layers so as to intersect with the gate bus lines. A method for manufacturing a liquid crystal display device having a bus line and a black matrix layer provided between the color filter layers while partially overlapping the source bus line, the method comprising: Mosquito Forming a source bus line made of a transparent conductive film on the color filter layer, disposing a black matrix material made of a photosensitive resin on the transparent substrate, and forming the black matrix layer on the transparent substrate. Forming a pattern by exposing with a predetermined exposure amount from the substrate side so that the thickness of the black matrix layer on the source bus line is not more than the thickness of the color filter layer and not less than 400 nm. Manufacturing method.