JP2001033790A - Liquid crystal display device and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve display quality of a liquid crystal display device by reinforcing pressure resistance between both substrates with a post spacer, which uniformly maintains the gap between the array substrate and the counter substrate, and preventing local uneven cell thickness in a liquid crystal cell from being generated by pressure added when the liquid crystal cell is manufactured. SOLUTION: A post spacer 20 having a planar flat part on the top is formed on an array substrate by exposing a negative photoresist via a photomask 22 having about 3 μm×3 μm unexposed part 22b inside about 7 μm×15 μm exposed part 22a and subsequently developing it. Therefore the area of the post spacer 20 in contact with the counter substrate is enlarged so as to heighten pressure resistance, between the array and the counter substrates, to the pressure added in manufacturing the liquid crystal cell.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display device in which a liquid crystal composition is sealed between substrates disposed opposite to each other, and the gap between the substrates is kept constant by using a columnar spacer made of a photosensitive resin. The present invention relates to a liquid crystal display device and a method for manufacturing a liquid crystal display device.

[0002]

2. Description of the Related Art In recent years, thin, lightweight and high-definition liquid crystal display devices have been developed in the field of information equipment such as computers and the field of video equipment such as televisions. Currently, most of the liquid crystal display devices generally used are composed of two glass substrates having electrodes and a liquid crystal composition sealed in a gap between the two glass substrates. Specifically, for example, in a color active matrix type liquid crystal display device, a thin film transistor having a semiconductor layer of amorphous silicon or the like on a first substrate, an array substrate, and pixel electrodes, signal line electrodes, and gate electrodes connected thereto are provided. And a color filter composed of three primary color layers. On the other hand, a counter electrode is formed on a counter substrate which is a second substrate. The array substrate and the opposing substrate are opposed to each other while maintaining a certain gap by a spacer, and the liquid crystal composition is sealed in the gap between the two substrates surrounded by the adhesive.

In recent years, instead of plastic beads having a uniform particle size used by being uniformly dispersed on the substrates, spacers for maintaining the gap between the two substrates constant have recently been used on a non-display area of either an array substrate or a counter substrate. A columnar spacer directly formed with a pattern has been developed.

In the case where a photosensitive resin is used as a material of such a columnar spacer, for example, if a negative photosensitive resin is used, the negative photosensitive resin applied to the substrate is patterned to form a columnar spacer. Conventionally, a columnar spacer having a predetermined shape has been obtained by exposing and developing using a photomask for ultraviolet exposure which makes the entire region corresponding to the cross-sectional shape of the columnar spacer an exposure region. When a positive type photosensitive resin is used as the spacer material, exposure and development are performed using a photomask for ultraviolet exposure which makes the entire area corresponding to the cross-section of the columnar spacer a non-exposed area.

[0005]

However, as in the prior art, the entire surface corresponding to the cross-sectional shape of the columnar spacer of the negative photosensitive resin is exposed, or the cross-sectional shape of the columnar spacer of the positive type photosensitive resin is exposed. When a columnar spacer is formed by exposing the entire surface of the region to be exposed, as shown in FIG. 16, the cross-sectional shape of the columnar spacer 40 is substantially hemispherical, regardless of whether a negative type or a positive type photosensitive resin is used. The top was formed in a dot shape. Therefore, the columnar spacer 40
The contact area with the opposing substrate 41 is small, and the columnar spacer 40 supports the other substrate 41 at the top point, and the two substrates are arranged facing each other via such a columnar spacer 40. When a liquid crystal cell is manufactured, the pressure resistance against the pressure applied between the two substrates in each step of manufacturing the liquid crystal cell is weak, and the liquid crystal cell locally generates cell thickness unevenness, and thus lowers the display quality of the liquid crystal display device. Had the problem of doing so.

In view of the above, the present invention has been made to solve the above-mentioned problems, and has been made to enhance the pressure resistance of a liquid crystal cell using columnar spacers formed by patterning a photosensitive resin, so that the liquid crystal cell can be made irrespective of the pressure applied when the liquid crystal cell is manufactured. It is an object of the present invention to provide a liquid crystal display device and a method for manufacturing the liquid crystal display device, which can maintain the gap uniformly over the entire surface and obtain good display quality without causing cell thickness unevenness.

[0007]

According to the present invention, as a means for solving the above problems, there is provided a liquid crystal display device comprising a liquid crystal composition sealed in a gap between two substrates disposed opposite to each other.
A columnar spacer made of a photosensitive resin is formed on at least one of the substrates, has a flat portion on the top, and keeps the gap uniform.

According to the present invention, the columnar spacer is in surface contact with the other substrate at the top and can support the other substrate with a wide contact area, so that the pressure resistance at the time of manufacturing the liquid crystal cell can be enhanced, The cell thickness of the liquid crystal display device is made uniform and the display quality of the liquid crystal display device is improved.

According to the present invention, as a means for solving the above-mentioned problems, a gap between two opposing substrates is uniformly held by a columnar spacer made of a negative photosensitive resin, and a liquid crystal composition is filled in the gap. In the method for manufacturing a liquid crystal display device encapsulating the substrate, a step of applying the negative photosensitive resin to at least one of the substrates, and an unexposed portion inside an exposed portion corresponding to the formation region of the columnar spacer. Performing a step of exposing the negative-type photosensitive resin through an exposure mask provided with the step of developing the negative-type photosensitive resin after the exposure to form a flat portion on the top of the columnar spacer. Things.

According to the present invention, as a means for solving the above-mentioned problems, a gap between two opposing substrates is uniformly held by a columnar spacer made of a positive photosensitive resin, and a liquid crystal composition is provided in the gap. In the method for manufacturing a liquid crystal display device, a step of applying the positive photosensitive resin to at least one of the substrates, and an exposed portion inside an unexposed portion corresponding to a region where the columnar spacer is formed. Performing a step of exposing the positive-type photosensitive resin through an exposure mask provided with a step of developing the positive-type photosensitive resin after exposure to form a flat portion on the top of the columnar spacer. Things.

According to the present invention, the contact area of the top of the columnar spacer with the other substrate can be increased by removing the top of the columnar spacer at the time of pattern formation and forming a flat portion on the top. An object of the present invention is to improve the display quality of the liquid crystal display device by enhancing the pressure resistance during the production of the liquid crystal cell, making the cell thickness of the liquid crystal cell uniform.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First, the principle of the present invention will be described. In a liquid crystal display device, when a columnar spacer made of a photosensitive resist is pattern-formed as a spacer for uniformly maintaining a gap between two substrates disposed opposite to each other, the shape of the columnar spacer is applied onto the substrate. It depends on the shape of the photomask that exposes the exposed photosensitive resist. Therefore, a negative photosensitive resist was patterned using photomasks A to D having different shapes each having an exposed portion and an unexposed portion as shown in Table 1, and columnar spacers were actually created. The cross-sectional shape as shown was obtained.

[Table 1] However, as shown in FIG.
Is coated with a black negative photosensitive resist 2 to a thickness of about 5.5 μm using a spinner, dried at 90 ° C. for 10 minutes, and exposed through a photomask 3 shown in Table 1 to an exposure dose of 30 μm.
After exposure at 0 mJ / cm ² , the film was developed with an alkaline aqueous solution having a pH of 11.5 and baked at 200 ° C. for 60 minutes.

(Photomask A) As shown in FIG. 2, a black negative photosensitive resist 2 is exposed through a photomask A having no exposed portion 4a and having an exposed portion 4a of 15 μm × 15 μm. After exposure and development, as shown in FIG. 3, a columnar spacer 4 having a substantially hemispherical cross section and a substantially pointed top was obtained.

(Photomask B) As shown in FIG.
3 μm × 3 μm inside 5 μm × 15 μm exposed portion 6 a
The black negative photosensitive resist 2 is exposed and developed through a photomask B having an unexposed portion 6b having an area ratio of the unexposed portion to the exposed portion of 4%. As shown in FIG. As a result, a columnar spacer 6 having a substantially hemispherical top having a flat flat portion near the top was obtained.

(Photomask C) As shown in FIG.
10 μm × 10 inside the exposed portion 7 a of 5 μm × 15 μm
FIG. 7 shows that the black negative photosensitive resist 2 is exposed and developed through a photomask C having an unexposed portion 7b of μm and an area ratio of the unexposed portion to the exposed portion of 44.4%.
As shown in FIG. 7, a columnar spacer 7 having a recess near the top of a substantially hemispherical cross section and having a ring-shaped flat portion on the top.
Was obtained.

(Photomask D) As shown in FIG.
14 μm × 14 inside the exposed portion 8 a of 5 μm × 15 μm
FIG. 9 shows a black negative photosensitive resist 2 having a non-exposed portion 8b of μm and a black negative photosensitive resist 2 developed through a photomask D having an area ratio of the unexposed portion to the exposed portion of 87.1%.
As shown in (1), a liquid crystal cell was formed using the columnar spacers 4 to 8 in which the central portion was completely removed and the remaining portion was a ring-shaped columnar spacer 8 having a height of about 3 μm, and the cell thickness was examined. As a result, it was found that in the case of using the columnar spacers 6 and 7 exposed through the photomasks B and C, no local cell thickness unevenness was observed and a uniform gap was obtained over the entire area. This corresponds to the exposed portions 6a, 7a, respectively.
By providing the unexposed portions 6b and 7b inside, the vicinity of the tops of the columnar spacers 6 and 7 are removed to form a flat portion, so that the columnar spacers 6 and 7 form a flat surface, not a point, respectively. Alternatively, by supporting with a ring-shaped surface, the pressure resistance is enhanced. Although the columnar spacer 8 formed by patterning using the photomask D had a ring-shaped flat portion at the top, the unexposed portion to be removed was too large, and the required height could not be secured. . Further, the columnar spacer 4 formed by patterning using the photomask A has a substantially hemispherical cross-sectional shape near the top, and the opposing substrate is supported at the apex by a point, so that the columnar spacer 4 is unsuitable for low pressure resistance.

The present invention has been made based on the above principle. Hereinafter, a first embodiment of the present invention will be described with reference to FIG.
This will be described with reference to FIGS. FIG. 10 is a schematic sectional view showing a main part of the color liquid crystal display device 10 according to the present invention. The color liquid crystal display device 10 is a so-called transmissive liquid crystal display device, and opposes an array substrate 11 and an opposing substrate 12 disposed so as to uniformly maintain a gap therebetween via a black columnar spacer 20. The liquid crystal composition 13 is disposed in the gap, and the gap is filled with the liquid crystal composition 13.

A gate electrode (not shown) in which a 0.3 μm thick molybdenum (Mo) film is formed on the first glass substrate 14 of the array substrate 11 by sputtering and then patterned in a predetermined shape by photolithography. Silicon oxide (SiOx) or silicon nitride (SiN)
x) of a gate insulating film (not shown) of 0.15 μm
After the film formation, a thin film transistor (hereinafter abbreviated as TFT) 16 provided with a semiconductor layer (not shown) made of a-Si is formed thereon.

Further, a negative photosensitive resist in which a red pigment is dispersed is applied over the entire surface of the TFT 16 through an interlayer insulating film (not shown) by a spinner, and dried at 90 ° C. for 10 minutes. Except through a photomask that irradiates only the portion where the red colored layer is formed with ultraviolet light except for the above, the exposure amount is set to 200 mJ / cm ^2, and then exposed to a 20% aqueous solution of potassium hydroxide (KOH) 1 wt%.
A red colored layer 17 formed by developing for 200 seconds and baking at 200 ° C. for 60 minutes is formed.

Similarly, a photosensitive resist in which a green (G) pigment is dispersed and a photosensitive resist in which a blue (B) pigment is dispersed are arranged on an interlayer insulating film by a photolithography technique. 0.5 μm red (R), green (G),
The color filter layer 18 in which the blue (B) colored layers are arranged is formed.

Next, the black columnar spacer 20 formed on the color filter layer 18 will be described in detail. After the color filter layer 18 is formed, as shown in FIG.
It is applied in a thickness of 5 μm and dried at 90 ° C. for 10 minutes. Next, as shown in FIG. 11B, a photomask 22 having a 3 μm × 3 μm unexposed portion 22 b inside the 7 μm × 15 μm exposed portion 22 a and having an area ratio of the unexposed portion to the exposed portion of 8.4%. Exposure dose of 300 mJ / cm ²
Exposes the negative photosensitive resist 21. Then Figure 11
As shown in (c), the negative photosensitive resist 21 is adjusted to pH =
Develop with alkaline aqueous solution of 11.5, 200 ℃, 60
4. Baking for a minute, a height having a flat flat portion on the top
A 2 μm columnar spacer 20 is formed.

After that, indium tin oxide (ITO) is deposited to a thickness of about 0.1 μm by sputtering, patterned in a predetermined shape by photolithography, and the pixel electrode 24 connected to the TFT 16 via the contact hole area 17a is formed. Form.

A polyimide solvent is uniformly applied to the array substrate 11 and the opposite substrate 12 having the common electrode 26 on the second glass substrate 25, and the alignment film 2 is
After forming 7a and 27b, a rubbing process is performed. Thereafter, the array substrate 11 and the opposing substrate 12 are arranged to face each other via the columnar spacer 20 and are bonded together using an adhesive made of an epoxy-based thermosetting resin. The liquid crystal composition 13 is injected into the gap therebetween, and the injection port is sealed with an ultraviolet curable resin. Further, polarizers 28a, 2b are provided outside the array substrate 11 and the counter substrate 12.
8b is attached, and the color liquid crystal display device 10 is completed.

When the color liquid crystal display device 10 performed display, high display quality was obtained without causing display defects due to local uneven cell thickness.

With this configuration, the columnar spacer 20
When the pattern is formed, the vicinity of the top is not exposed, so that the columnar spacer forms a flat flat portion on the top. Thereby, when the array substrate 11 and the opposing substrate 12 are arranged to oppose each other, the contact area of the columnar spacer 20 with the opposing substrate 12 is increased, and the pressure resistance against the pressure applied between the array substrate 11 and the opposing substrate 12 at the time of manufacturing the liquid crystal cell is increased. . Therefore, the liquid crystal cell can maintain the gap between the array substrate 11 and the counter substrate 12 uniformly over the entire surface irrespective of the pressurization at the time of manufacturing, and can prevent display defects due to local uneven cell thickness of the liquid crystal display device. The display quality can be improved.

Next, a second embodiment of the present invention will be described with reference to FIGS. In this embodiment, since a black columnar spacer is formed using a positive photosensitive resist, the photomask used in the first embodiment has a configuration in which exposed and unexposed portions are reversed. Is used to pattern the columnar spacers.
Since the present embodiment is the same as the above-described embodiment, the same portions are denoted by the same reference numerals and description thereof will be omitted.

That is, the color liquid crystal display device 3 of the present embodiment
In FIG. 13, after forming the same TFT 16 and color filter layer 18 on the array substrate 31 as in the first embodiment, FIG.
As shown in (a), a black positive photosensitive resist 32 is applied to a thickness of about 5.5 μm using a spinner,
C. Dry for 10 minutes. Next, as shown in FIG. 13B, 3 μm × 3 μm is formed inside the unexposed portion 33 a of 7 μm × 15 μm.
Through a photomask 33 having an exposed portion 33b of μm and an area ratio of an exposed portion to an unexposed portion, which is 8.4%,
Positive photosensitive resist 32 at an exposure dose of 300 mJ / cm ²
Is exposed. Thereafter, as shown in FIG. 13 (c), the positive photosensitive resist 32 is developed with an alkaline aqueous solution having a pH of 11.5, and baked at 200 ° C. for 60 minutes to have a height 5 having a flat flat portion on the top. 2 .mu.m columnar spacers 34 are formed.

Thereafter, after forming the same pixel electrode 24 as in the first embodiment, an alignment film 27a is applied to form an array substrate 31. Further, after forming the liquid crystal cell by arranging the array substrate 34 and the opposing substrate 12 with the columnar spacer 34 interposed therebetween,
The liquid crystal composition is sealed in the gap between the two substrates 31 and 12, and the polarizing plates 28a and 28b are further adhered.
Complete 0.

According to this structure, as in the first embodiment, the contact area between the columnar spacer 34 and the opposing substrate 12 is increased by the flat portion formed on the top, so that the array substrate 31 and the The pressure resistance against the pressure applied between the opposing substrates 12 is increased, and the gap between the substrates 11 and 12 can be uniformly maintained over the entire surface regardless of the pressure applied during the liquid crystal cell production. Display defects can be prevented, and display quality can be improved.

The present invention is not limited to the above embodiment, but may be modified without departing from the spirit of the invention. For example, the columnar spacer may be formed on either the array substrate or the counter substrate. good. When forming the columnar spacer, the size and shape of the exposed portion and the unexposed portion of the photomask are arbitrary depending on the size and shape of the columnar spacer.For example, when the columnar spacer is formed of a negative photosensitive resin. The size of the exposed portion and the unexposed portion inside thereof is preferably such that the width of the unexposed portion is 23 μm or less, and the width of the exposed portion around the portion is 2 μm or more,
It is preferable that the area ratio of the unexposed portion to the exposed portion is also 75% or less. Further, the amount of light when exposing the photosensitive resin through the photomask is not limited, and the structures of the liquid crystal display device and the TFT are arbitrary.

[0031]

As described above, according to the present invention, when patterning a columnar spacer made of a photosensitive resin, the photosensitive resin is removed through a photomask formed so as to remove the vicinity of the top of the columnar spacer. Since the exposure forms a flat portion on the top of the columnar spacer, the contact area between the top of the columnar spacer and the opposing substrate is increased. Therefore, when two substrates are bonded to each other via a columnar spacer to produce a liquid crystal cell, the pressure resistance of both substrates against the pressure applied between the two substrates is increased, and the liquid crystal cell does not cause local uneven cell thickness. It is possible to obtain a liquid crystal display device that can maintain a uniform gap and that is free from display unevenness due to cell thickness unevenness and has high display quality.

[Brief description of the drawings]

FIG. 1 is a schematic explanatory view showing pattern formation of a columnar spacer according to the principle of the present invention.

FIG. 2 is a schematic plan view showing a photomask A according to the principle of the present invention.

FIG. 3 is a schematic explanatory view showing a cross-sectional shape of a columnar spacer formed using a photomask A according to the principle of the present invention.

FIG. 4 is a schematic plan view showing a photomask B according to the principle of the present invention.

FIG. 5 is a schematic explanatory view showing a sectional shape of a columnar spacer formed using a photomask B according to the principle of the present invention.

FIG. 6 is a schematic plan view showing a photomask C according to the principle of the present invention.

FIG. 7 is a schematic explanatory view showing a sectional shape of a columnar spacer formed using a photomask C according to the principle of the present invention.

FIG. 8 is a schematic plan view showing a photomask D according to the principle of the present invention.

FIG. 9 is a schematic explanatory view showing a cross-sectional shape of a columnar spacer formed using a photomask D according to the principle of the present invention.

FIG. 10 is a partial schematic cross-sectional view showing the liquid crystal display device according to the first embodiment of the present invention.

11A and 11B show a manufacturing process of the columnar spacer according to the first embodiment of the present invention, wherein FIG. 11A shows the process at the time of applying the negative photosensitive resist, FIG. 11B shows the process at the time of exposing the negative photosensitive resist, and FIG.
FIG. 4 is a schematic explanatory view showing the state at the time of developing the negative photosensitive resist.

FIG. 12 is a schematic plan view showing a photomask according to the first embodiment of the present invention.

FIG. 13 is a partial schematic cross-sectional view illustrating a liquid crystal display device according to a second embodiment of the present invention.

14A and 14B show a manufacturing process of the columnar spacer according to the second embodiment of the present invention, wherein FIG. 14A shows the process at the time of applying the negative photosensitive resist, FIG. 14B shows the process at the time of exposing the negative photosensitive resist, and FIG.
FIG. 4 is a schematic explanatory view showing the state at the time of developing the negative photosensitive resist.

FIG. 15 is a schematic plan view illustrating a photomask according to a second embodiment of the present invention.

FIG. 16 is a schematic explanatory view showing a cross-sectional shape of a conventional columnar spacer.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 ... Color liquid crystal display device 11 ... Array substrate 12 ... Counter substrate 13 ... Liquid crystal composition 14 ... First glass substrate 16 ... Thin film transistor 18 ... Color filter layer 20 ... Columnar spacer 21 ... Negative photosensitive resist 22 ... Photo mask 24 ... Pixel electrodes 27a, 27b ... Alignment film

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2H089 HA10 LA04 LA09 MA04X NA05 NA14 PA06 QA04 QA14 TA09 TA12 TA13 5C094 AA03 AA36 AA43 AA47 AA48 AA55 BA43 DA12 DA13 EB03 EC03 FA01 FA02 FB01 FB15 GB01 GB10 JA01 JA08

Claims (9)

[Claims] 1. A liquid crystal display device in which a liquid crystal composition is sealed in a gap between two substrates arranged opposite to each other, the liquid crystal display device being formed on at least one of the substrates, having a flat portion on the top, and A liquid crystal display device comprising a columnar spacer made of a photosensitive resin that uniformly holds the liquid crystal. 2. A columnar spacer is made of a negative photosensitive resin formed by patterning by exposing a region where the columnar spacer is formed, and a flat portion is formed on the columnar top by not exposing the vicinity of the columnar top. The liquid crystal display device according to claim 1, wherein the liquid crystal display device is formed. 3. The columnar spacer is made of a positive photosensitive resin that is patterned by not exposing a region where the columnar spacer is formed, and a flat portion is formed on the top by exposing the vicinity of the top of the columnar spacer. The liquid crystal display device according to claim 1, wherein the liquid crystal display device is formed. 4. A method for manufacturing a liquid crystal display device, comprising: a gap between two substrates disposed opposite to each other, uniformly held by a columnar spacer made of a negative photosensitive resin, and a liquid crystal composition sealed in the gap. A step of applying the negative photosensitive resin to at least one of the substrates, and the negative mold through an exposure mask provided with an unexposed portion inside an exposed portion corresponding to the formation region of the columnar spacer. Exposing the photosensitive resin,
Developing the negative photosensitive resin after the exposure, and forming a flat portion on the top of the columnar spacer. 5. An exposure mask according to claim 4, wherein the area of the unexposed portion is not more than 75% of the area of the exposed portion.
3. The method for manufacturing a liquid crystal display device according to item 1. 6. The width of an unexposed portion of an exposure mask is 23 μm.
The width of the exposed portion around the unexposed portion is 2 μm
The method of manufacturing a liquid crystal display device according to claim 4, wherein: 7. A method for manufacturing a liquid crystal display device, comprising: a gap between two substrates disposed opposite to each other, uniformly held by a columnar spacer made of a positive photosensitive resin, and a liquid crystal composition sealed in the gap. A step of applying the positive-type photosensitive resin to at least one of the substrates, and the positive-type photosensitive resin through an exposure mask provided with an exposed portion inside an unexposed portion corresponding to a formation region of the columnar spacer. Exposing the photosensitive resin,
Developing the positive-type photosensitive resin after exposure, and forming a flat portion on the top of the columnar spacer. 8. The exposure mask according to claim 7, wherein the area of the exposed portion of the exposure mask is 75% or less of the area of the unexposed portion.
3. The method for manufacturing a liquid crystal display device according to item 1. 9. The exposure mask according to claim 7, wherein the width of the exposed portion of the exposure mask is 23 μm or less, and the width of the unexposed portion around the exposed portion is 2 μm or more. A method for manufacturing a liquid crystal display device.