KR20070069829A - Liquid crystal display device and method for fabricating the same - Google Patents

Abstract

A liquid crystal display device and a fabricating method thereof are provided to form a black matrix and column spacers simultaneously by a diffraction exposure step applied to color filter layers and an overcoat layer, thereby removing stepped difference failure on a surface of the overcoat layer caused by overlapping between the black matrix and the color filter layers. A liquid crystal display device includes color filter layers(123) formed on a first substrate(121), an overcoat layer(124) formed on the entire surface of the first substrate including the color filter layers for flattening the entire surface, a black matrix(122) and column spacers(131) integrally formed on the overcoat layer, a second substrate(111) facing the first substrate and formed with thin film transistors(TFT) at intersections between a plurality of gate and data lines(115) thereon, and a liquid crystal layer(129) formed between the first and second substrates.

Description

Liquid Crystal Display Device and Method for Manufacturing the Same {Liquid Crystal Display Device And Method For Fabricating The Same}

1 is a cross-sectional view of a liquid crystal display device according to the prior art.

2A to 2E are cross-sectional views of a liquid crystal display device according to the prior art.

3 is a cross-sectional view of a liquid crystal display device according to the present invention.

4 is a plan view of a black matrix and column spacer according to the present invention;

5 is a cross-sectional view taken along line II ′ of FIG. 4.

6A to 6E are cross-sectional views of a liquid crystal display device according to the present invention.

* Explanation of symbols on the main parts of the drawings

111: TFT array substrate 115: data wiring

117: pixel electrode 118: common electrode

121: color filter array substrate 122: black matrix

123: color filter layer 124: overcoat layer

129: liquid crystal layer 126: sealant

131: column spacer

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display device (LCD), and in particular, to form a black matrix and a column spacer at the same time by applying a diffraction exposure process, to eliminate defects caused by non-uniformity of the liquid crystal cell, and a manufacture thereof. It is about a method.

Recently, the liquid crystal display device has a high contrast ratio, is suitable for gray scale display or moving image display, and has low power consumption. Therefore, the liquid crystal display device is gradually used as an alternative means to overcome the disadvantage of cathode ray tube (CRT). It is expanding.

Such a liquid crystal display device typically includes a TFT array substrate in which a thin film transistor and a pixel electrode are formed in each unit pixel defined by a gate wiring and a data wiring, and a color filter array in which a black matrix, a color filter layer, and a common electrode are formed. It consists of a substrate and a liquid crystal layer interposed between the two substrates and the array direction is controlled by a vertical electric field formed between the pixel electrode and the common electrode to display an image by various external signals.

At this time, the common electrode may be formed between the pixel electrodes on the TFT array substrate. In this case, the alignment direction is controlled by the transverse electric field generated between the pixel electrode and the common electrode.

Hereinafter, a liquid crystal display device and a method of manufacturing the same according to the related art will be described with reference to the accompanying drawings.

1 is a cross-sectional view of a liquid crystal display device according to the prior art, and FIGS. 2A to 2E are process cross-sectional views of the liquid crystal display device according to the prior art.

In the liquid crystal display device according to the related art, as shown in FIG. 1, the color filter array substrate 21 as the upper substrate and the TFT (Thin Film Transistor) array substrate 11 as the lower substrate are opposed to each other. The liquid crystal layer 29 is disposed therebetween, and is driven by switching a TFT added to hundreds of thousands of unit pixels through a pixel selection gate wiring to apply a voltage to the pixel. do.

In this case, the TFT array substrate 11 includes a gate wiring (not shown) and a data wiring 15 insulated from each other by the gate insulating film 13, a thin film transistor (TFT) formed at an intersection of the two wirings, A pixel electrode 17 penetrating the passivation layer 16 and connected to the thin film transistor TFT and a common electrode 18 disposed in parallel with the pixel electrode 17 to generate a transverse electric field are formed.

In addition, the color filter array substrate 21 includes a black matrix 22 for preventing light leakage, a color filter layer 23 of red, green, and blue for implementing colors, and the color. An overcoat layer 24 formed on the entire surface including the filter layer 23 is formed.

The sealant 41 is further provided at edges of the color filter array substrate 21 and the TFT array substrate 11 to completely adhere the two substrates and prevent liquid crystals from flowing out. A spacer 31 is further provided to keep the substrate gap constant.

At this time, if the gap between the two substrates is not constant, the transmittance of light passing through the portion is changed and brightness is uneven, so that the spacer gap is inserted between the two substrates to keep the substrate gap constant.

The spacers may be formed as ball spacers or column spacers, and the ball spacers may be formed by a scattering method, and the column spacers may be selectively removed after applying an organic polymer to a substrate. It is formed by a photolithography technique.

However, in the case of a liquid crystal display device having a low cell gap and large area, it is difficult to manufacture the ball spacer to a size of 4 to 5 μm or less, and thus, a column spacer is often used.

Hereinafter, a manufacturing process of the liquid crystal display device will be described.

First, as shown in FIG. 2A, a metal or carbon-based organic material, such as chromium oxide (CrOx) or chromium (Cr) having an optical density of 3.5 or more, on a predetermined portion of the color filter array substrate 21. After applying the material, it is patterned by photolithograpy technology to form the black matrix 22.

Thereafter, a color resist colored with R (Red) color is applied and patterned on the entire surface including the black matrix 22 to form a color filter layer of R color. A color filter layer of G (Green) color and a color filter layer of B (Blue) color are also formed in the same manner to complete the color filter layers 23 of R, G, and B.

Then, as shown in FIG. 2B, in order to planarize the surface of the color filter array substrate 21, an overcoat layer 24 is formed by coating an acrylic resin, which is an organic material, on the entire surface including the color filter layer 23.

Subsequently, as shown in FIG. 2C, after the photosensitive resin film 31d is applied to the entire surface including the overcoat layer 24 to a predetermined thickness and cured, the exposure mask 50 is aligned, followed by an exposure mask. UV light is irradiated through the light-transmitting portion of 50 to expose the photosensitive resin film 31d.

Next, as shown in FIG. 2D, the unexposed photoresist is removed by chemically treating the exposed photosensitive resin film to complete the column spacer 31 having the surface of the clay pattern.

Thereafter, as shown in FIG. 2E, a sealant (not shown) serving as an adhesive is printed on the edge of the TFT array substrate 11 on which the thin film transistor is formed, and then the two substrates are opposed to each other, The liquid crystal layer 29 is formed between the substrates to complete the liquid crystal display device.

However, the liquid crystal display device and its manufacturing method according to the prior art have the following problems.

That is, as the R, G, and B color filter layers are formed in separate processes, a problem arises in that a step is generated between the R, G, and B color filter layers depending on the characteristics of the color resist and the degree of exposure.

Furthermore, even if the step difference between the color filter layer overlapping the black matrix and the color filter layer not overlapping the black matrix is formed unevenly, the step compensation is not greatly improved. In particular, the step unevenness due to the overlap of the black matrix and the color filter layer is further increased when the black matrix is thickly formed of an organic film of carbon type.

As shown in FIG. 2D, the height difference ΔH1 between the adjacent column spacers 31 was measured, resulting in a step difference of 2000 μs or more.

As such, when the step of the column spacer is nonuniform, the liquid crystal cell gap eventually becomes nonuniform, so that it is difficult to drop the amount of liquid crystal as accurate as the designed specifications when injecting or dropping the liquid crystal between the TFT array substrate and the color filter array substrate.

Therefore, a somewhat larger or smaller amount of liquid crystal is interposed between the two substrates. In this case, after the liquid crystal display device is completed, image quality defects such as gravity defects, bright spots, and stains due to gravity or external stimulus are generated.

Herein, when the liquid crystal is excessively formed, that is, when the liquid crystal is excessively formed, the volume of the liquid crystal layer increases due to the temperature increase of the liquid crystal layer, and the liquid crystal cell gap becomes larger than the spacer. Gravity failure occurs due to the weight of the liquid crystal cell gap being unevenly lowered through the spacer.

In the case where less liquid crystal is formed, when the screen of the liquid crystal display is rubbed or pressed, the liquid crystal moves to the next space and cannot be returned to its original position due to the flat surface structure of the column spacer. Becomes different, resulting in poor image quality.

The present invention has been made to solve the above problems, the liquid crystal display device to eliminate the step difference of the column spacer and reduce the number of mask process by applying a diffraction exposure process simultaneously to form a black matrix and a column spacer The purpose is to provide a manufacturing method.

The liquid crystal display device of the present invention for achieving the above object is a color filter layer formed on the first substrate, an overcoat layer formed on the entire surface including the color filter layer to planarize the surface, and integrally formed on the overcoat layer A black matrix and column spacer to be formed, a second substrate having a thin film transistor formed at a portion of the first substrate facing the first substrate and crossing a plurality of gate wirings and data wirings, and a liquid crystal layer formed between the first and second substrates. Characterized in that comprises a.

In addition, a method of manufacturing a liquid crystal display device for achieving another object of the present invention includes the steps of providing a first substrate and a second substrate, forming a color filter layer on the first substrate, and including the color filter layer Forming an overcoat layer on the entire surface, forming a photosensitive resin on the entire surface including the overcoat layer, diffractive exposure and patterning the photosensitive resin to simultaneously form a black matrix and a column spacer, and the first substrate Or forming a sealant on the edge of the second substrate to oppose and bonding the liquid crystal layer between the first and second substrates.

As described above, the column spacer according to the present invention is integrally formed with the black matrix, and is intended to improve the column spacer step difference with respect to the entire panel.

Hereinafter, a liquid crystal display device and a method of manufacturing the same according to the present invention will be described in detail with reference to the accompanying drawings.

3 is a cross-sectional view of a liquid crystal display device according to the present invention, FIG. 4 is a plan view of a black matrix and a column spacer according to the present invention, FIG. 5 is a sectional view taken along the line II ′ of FIG. 4, and FIGS. 6E is a process cross-sectional view of a liquid crystal display device according to the present invention.

In the liquid crystal display according to the present invention, as shown in FIG. 3, the color filter array substrate 121 serving as the upper substrate and the TFT (Thin Film Transistor) array substrate 111 serving as the lower substrate face each other. The liquid crystal layer 129 having dielectric anisotropy and a column spacer 131 for uniformly maintaining the cell gap of the liquid crystal layer are disposed between the two substrates, and the column spacer 131 is the color filter array substrate. It is characterized in that it is formed integrally with the black matrix 122 of (121).

Specifically, the TFT array substrate 111 includes gate wirings (not shown) and data wirings 115 which are insulated from each other by the gate insulating layer 113 by vertically crossing each other to define a sub-pixel. A thin film transistor (TFT) formed at an intersection of the gate line and the data line to switch on / off of a voltage to change an arrangement direction of liquid crystal molecules, and a liquid crystal layer electrically connected to the thin film transistor at each unit pixel The common electrode 118 controlling the liquid crystal direction by generating a transverse electric field together with the pixel electrode 117 spaced apart from the pixel electrode 117 at a predetermined interval and applying a voltage to the pixel electrode 117. Is formed.

In addition, the color filter array substrate 121 includes red, green, and blue color filter layers 123 arranged in a predetermined order for each unit pixel to implement colors, and the R, G And an overcoat layer 124 formed on the entire surface including the color filter layer 123 of B and flattening the surface, and shielding light leakage in an area where the separation between R, G, and B cells and the electric field are unstable on the overcoat layer. The black matrix 122 is formed.

In this case, the black matrix 122 has a column spacer 131 integrally formed thereon, and has a structure in which the color spacer is attached to the black matrix.

As illustrated in FIGS. 4 and 5, the black matrix 122 is provided so as to correspond to an edge of a unit pixel (a portion where gate lines and data lines are formed) and an area where a thin film transistor is formed.

The column spacer 131 is formed in a dot pattern on a black matrix, and unit pixel edges (gate wirings and data wirings) are formed instead of an internal area of a unit pixel displaying an image in order to prevent light leakage. Part) to correspond to the area.

The column spacers are spaced apart at regular intervals and are formed on the color filter array substrate. According to the liquid crystal display, one column per pixel, two pixels, or one pixel may be disposed. In FIG. 4, one column per pixel is disposed. The structure is shown.

The sealant 141 is further provided at edges of the color filter array substrate 21 and the TFT array substrate 11 to completely adhere the two substrates and prevent liquid crystals from flowing out.

Hereinafter, the method of manufacturing the liquid crystal display device will be described in detail.

First, as shown in FIG. 6A, a color resist containing a pigment that implements color by a spin method, a roll coat method, or the like is applied to the entire color filter array substrate 121. 1 μm to 3 μm thickness is applied and patterned by photolithography to form color filter layers 123 of R, G, and B.

In this case, a color resist colored with red color is applied and patterned to form an R color filter layer, and a green color colored color resist is applied and patterned to form a G color filter layer on the entire surface including the R color filter layer. Then, the color filter layers of R, G, and B are completed by coating and patterning a color resist colored with blue on the entire surface including the R and G color filter layers to form a B color filter layer. At this time, it is not limited to forming the color filter layer in the order of R, G, and B.

Next, a planarization film is coated by a spin coating method using an acrylic resin or a polyimide resin on the entire surface including the color filter layers 123 of R, G, and B, and has a thickness of about 1.5 to 2 μm. A transparent overcoat layer 124 is formed.

At this time, since the color filter layer is not formed on the black matrix, a sudden step difference caused by the overlapping color filter layer on the black matrix is prevented in the past, and as a result, the flatness of the overcoat layer formed on the color filter layer is also excellent.

Thereafter, as illustrated in FIG. 5B, an opaque photosensitive resin 131d is thickly applied to the entire surface including the overcoat layer 124. Thereafter, the photosensitive resin is patterned to simultaneously form a black matrix and a column spacer.

The photosensitive resin 131d may be an organic material including carbon black particles, an organic material using titanium oxide (TiOx) particles, or an organic material mixed with a black color pigment, or the Organic materials in a form including at least one of carbon particles, titanium oxide particles, and black color pigments may be used.

In addition, since the black matrix is formed by patterning the photosensitive resin, the photosensitive resin is formed of a material having an optical density of 4.0 or more. Light density is closely related to the contrast characteristic of the device, which represents the relative ratio of the luminance at the black level and the luminance at the white level, so be careful when selecting the material.

In addition, since the photosensitive resin is patterned to form a column spacer, a material having excellent elastic restoring force is selected as the photosensitive resin to maintain the shape of the column spacer.

Subsequently, as shown in FIG. 5C, the diffraction exposure mask 150 is aligned on the photosensitive resin 131d and irradiated with UV to diffract and expose the photosensitive resin. For diffraction exposure, a half-tone mask or slit mask is used.

In the case of the slit mask, it is divided into three regions: a transmissive portion (A), a semi-transmissive portion (B) and a light shielding portion (C). The light transmissive metal is not covered in the transmissive portion (A), so that the light transmittance is 100%. In the light shielding portion C, a light blocking metal is formed so that the light transmittance is 0%, and in the transflective portion B, a plurality of slits are formed between the light blocking metals, so that the light transmittance is 10% or more and 40% or less. At this time, the light transmittance of the transflective portion depends on the slit density.

Therefore, the remaining thickness of the photosensitive resin 131d diffracted and exposed by the slit mask 150 is also divided into three regions of the complete exposure portion, the complete non-exposure portion, and the diffraction exposure portion.

In this case, the fully exposed portion corresponds to the transmissive portion A of the slit mask 150, the completely non-exposed portion corresponds to the light shielding portion C, and the diffractive exposure portion is formed on the semi-transparent portion B in which a plurality of slits are formed. Corresponds.

In this way, the diffracted photosensitive resin 131d remains as it is in the fully exposed portion, is formed thinner than other portions only in the diffractive exposure portion, and is completely removed only in the completely non-exposed portion.

Therefore, when the photosensitive resin 131d is diffracted, developed, and cured using a diffraction mask, as shown in FIG. 5D, the photosensitive resin corresponding to the fully exposed portion is thickened to form the column spacer 131. The photosensitive resin corresponding to the diffractive exposure portion is formed to have a thin thickness to form a black matrix 122, and the photosensitive resin corresponding to the complete exposure portion is completely removed.

As a result, the integral black matrix and the column spacer are simultaneously formed. Therefore, the number of times of mask use can be reduced as compared with the prior art in which the black matrix and the column spacer are respectively formed.

Next, as shown in FIG. 5E, a gate wiring and a data wiring are formed on the TFT array substrate 111, and a thin film transistor (TFT) is formed at a portion where the two wirings cross each other, and then alternately parallel in a unit pixel. The common electrode and the pixel electrode are formed.

Subsequently, a sealant (not shown) is formed on the edge of the substrate by screen printing, dispensing, or the like by using a polymer having excellent adhesion such as an epoxy resin, and opposing to the color filter array substrate 121. .

Then, the two substrates are bonded together as described above by applying a high pressure (hot pressure) and heat of about 180 ℃ to completely adhere the two substrates.

Next, a liquid crystal panel having a required size is obtained by injecting and encapsulating a liquid crystal through the liquid crystal inlet between the two opposing substrates bonded as described above.

That is, the adhered liquid crystal cell is introduced into the vacuum chamber to immerse the liquid crystal inlet in the liquid crystal tray, vacuum degassing the inside of the cell, and supply the inert gas to make the vacuum chamber at atmospheric pressure. At this time, the liquid crystal is injected between the substrate due to the difference in the atmospheric pressure between the liquid crystal cell and the vacuum chamber. Nitrogen (N ₂ ) gas is used as the inert gas, and the liquid crystal injection rate is determined by the gas supply rate.

In recent years, as the liquid crystal display device is enlarged in size, the liquid crystal dropping method does not depend on the above-mentioned liquid crystal injection method, but also the liquid crystal dropping method of forming a liquid crystal layer by dropping and spreading the liquid crystal evenly on the inner surface of the substrate before the substrate opposing bonding.

Thus, the liquid crystal display device according to the present invention is completed.

The present invention described above is not limited to the above-described embodiments and the accompanying drawings, and various substitutions, modifications, and changes can be made in the art without departing from the technical spirit of the present invention. It will be clear to those of ordinary knowledge.

For example, in the above, the embodiment has been described only for a transverse electric field type liquid crystal display device having both a pixel electrode and a common electrode on a TFT array substrate to generate a transverse electric field. However, the present invention is not limited thereto. The present invention can also be applied to a TN mode liquid crystal display device in which a common electrode is formed on a filter array substrate to generate an electric field. In this case, the common electrode formed on the color filter array substrate is formed on the entire surface between the overcoat layer and the black matrix.

As described above, the liquid crystal display device and the manufacturing method thereof according to the present invention have the following effects.

That is, by forming a black matrix and a column spacer at the same time by applying a diffraction exposure process on the color filter layer and the overcoat layer, the step difference of the surface of the overcoat layer due to the overlap of the black matrix and the color filter layer, which is a conventional problem, is removed. There is no difference in height between column spacers for.

As a result, the liquid crystal cell gap becomes uniform, so that the liquid crystal can be injected as precisely as the specification designed for injecting or dropping the liquid crystal after bonding of the TFT array substrate and the color filter array substrate.

Therefore, after the liquid crystal panel is completed, image quality defects such as bright spots and stains due to gravity failure and external stimulus are removed. Therefore, the reliability of the liquid crystal display device is improved and the image quality is improved.

In addition, by simultaneously forming the black matrix and the column spacer, the number of times of use of the mask can be reduced compared to the conventional formation of the black matrix and the column spacer, respectively, and the cost of using the exposure apparatus and the exposure mask can be reduced.

Claims (11)

A color filter layer formed on the first substrate, An overcoat layer formed on the entire surface including the color filter layer to planarize the surface; A black matrix and column spacer formed integrally on the overcoat layer, A second substrate having a thin film transistor formed at a portion facing the first substrate and crossing a plurality of gate lines and data lines; And a liquid crystal layer formed between the first and second substrates. The method of claim 1, And a column spacer attached to the black matrix. The method of claim 1, The column spacer has a dot pattern. The method of claim 1, The column spacer is disposed above the gate line or the data line. The method of claim 1, And a common electrode between the overcoat layer and the black matrix. Providing a first substrate and a second substrate, Forming a color filter layer on the first substrate; Forming an overcoat layer on the entire surface including the color filter layer; Forming a photosensitive resin on the entire surface including the overcoat layer; Diffractive exposure and patterning the photosensitive resin to simultaneously form a black matrix and a column spacer; Forming a sealant on an edge of the first substrate or the second substrate to face each other; And forming a liquid crystal layer between the first and second substrates. The method of claim 6, And a diffraction exposure mask of a slit mask or a half-tone mask is used for diffraction exposure of the photosensitive resin film. The method of claim 7, wherein The diffraction exposure mask is a manufacturing method of a liquid crystal display device, characterized in that consisting of a transmissive portion for transmitting 100% of light, a transflective portion for transmitting 10-40% of light and a light shielding portion for shielding light. The method of claim 8, Align the transmission portion of the diffraction exposure mask where the column spacer is to be formed, And aligning the transflective portion of the diffraction exposure mask where the black matrix is to be formed. The method of claim 6, The photosensitive resin is a method of manufacturing a liquid crystal display device, characterized in that formed with a material having a light density of 4.0 or more. The method of claim 6, The photosensitive resin may be an organic material including carbon black particles, an organic material using titanium oxide (TiOx) particles, an organic material mixed with a black color pigment, or the carbon particles ( A liquid crystal display device, characterized in that any one selected from organic materials in a mixed form including at least one of carbon particles, titanium oxide particles, and black color pigments. Manufacturing method.

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