KR20020047602A - liquid crystal display device - Google Patents

Abstract

PURPOSE: A liquid crystal display is provided to improve adhesive strength between an overcoat layer and a substrate so as to prevent a seal pattern from being broken, thereby increasing aperture ratio. CONSTITUTION: The first black matrix(311) is formed on the first substrate(310). An overcoat layer(313) covers red, green and blue color filters. The overcoat layer has a flat surface. A plurality of gate lines and data lines are formed on the overcoat layer and intersect each other. A thin film transistor connected to the gate lines and the data lines. A pixel electrode receives a signal from the thin film transistor. The second substrate(410) is placed above the first substrate, having a predetermined distance between the two substrates. The second black matrix(420) is formed on the inner side of the second substrate and placed at the marginal portion of the second substrate. A transparent electrode(430) is formed under the second black matrix and generates an electric field together with the pixel electrode. A seal pattern(450) is placed at the marginal portion between the first and second substrates and located corresponding to the first and second black matrices. A liquid crystal layer is filled inside the seal pattern between the first and second substrates.

Description

Liquid crystal display device

The present invention relates to a liquid crystal display device, and more particularly, to a liquid crystal display device in which a color filter is formed on an array substrate.

Recently, with the rapid development of the information society, there is a need for a flat panel display having excellent characteristics such as thinning, light weight, and low power consumption. Among them, a liquid crystal display having excellent color reproducibility, etc. displays are actively being developed.

In general, a liquid crystal display device arranges two substrates on which electrodes are formed so that the surfaces on which the two electrodes are formed face each other, injects a liquid crystal material between the two substrates, and applies a voltage to the two electrodes to generate an electric field. By moving the liquid crystal molecules, the image is expressed by the transmittance of light that varies accordingly.

The lower substrate of the liquid crystal display is formed by repeating a process of forming a thin film and photolithography with an array substrate including a thin film transistor for applying a signal to a pixel electrode. The upper substrate is a substrate including a color filter. Three colors of red (R), green (G) and blue (B) are sequentially arranged, and are produced by methods such as pigment dispersion, dyeing, and electrodeposition.

Hereinafter, a structure of a general liquid crystal display device will be described with reference to the accompanying drawings.

1 is a cross-sectional view of a general liquid crystal display.

As shown in FIG. 1, the liquid crystal display device includes a first area A in which an image is represented and a second area B in which a pad (not shown) connected to an external driving circuit is positioned to express an image. Divided.

In the first region A, the lower array substrate has a gate electrode 21 made of a conductive material such as a metal on the transparent first substrate 10, and a silicon nitride film (SiN _x ) or a silicon oxide film (SiO) formed thereon. _The gate insulating film 30 made of ₂ ) covers the gate electrode 21. An active layer 41 made of amorphous silicon is formed on the gate insulating layer 30 on the gate electrode 21, and ohmic contact layers 51 and 52 made of amorphous silicon doped with impurities are formed thereon.

Source and drain electrodes 61 and 62 made of a conductive material such as a metal are formed on the ohmic contact layers 51 and 52, and the source and drain electrodes 61 and 62 together with the gate electrode 21 are thin film transistors. (T).

Although not shown, the gate electrode 21 is connected to the gate wiring, the source electrode 61 is connected to the data wiring, and the gate wiring and the data wiring are orthogonal to each other to define the pixel region.

Subsequently, a passivation layer 70 made of a silicon nitride film, a silicon oxide film, or an organic insulating layer is formed on the source and drain electrodes 61 and 62, and the passivation layer 70 has a contact hole 71 exposing the drain electrode 62. Has

A pixel electrode 81 made of a transparent conductive material is formed in the pixel area above the passivation layer 70, and the pixel electrode 81 is connected to the drain electrode 62 through the contact hole 71.

On the other hand, the second substrate 110 is spaced apart from the first substrate 10 at regular intervals on the first substrate 10, and the black matrix 121 is disposed on the inner surface of the second substrate 110. ) Is formed at a position corresponding to the thin film transistor T. Although not illustrated, the black matrix 121 covers portions other than the pixel electrode 81. A color filter 131 is formed below the black matrix 121. The color filters 131 sequentially repeat red, green, and blue colors, and one color corresponds to one pixel area. The common electrode 141 made of a transparent conductive material is formed under the color filter 131.

The liquid crystal layer 150 is injected between the two substrates 10 and 110.

Meanwhile, the common electrode 141 of the upper substrate 110 extends to the second region B, and liquid crystal injection is performed between the lower substrate 10 and the upper substrate 110 of the second region B. FIG. A seal pattern 160 is formed to form a gap for preventing the leakage of the injected liquid crystal.

Such a liquid crystal display includes a process of manufacturing a lower array substrate on which a thin film transistor and a pixel electrode are arranged, a process of manufacturing an upper color filter substrate including a color filter and a common electrode, an arrangement of the two substrates, and a liquid crystal material It is formed by a liquid crystal cell process consisting of the injection and encapsulation of a, and the attachment of a polarizing plate.

FIG. 2 is a flowchart illustrating a general liquid crystal cell manufacturing process, and will be briefly described with reference to FIG. 2.

First, a lower thin film transistor substrate including a thin film transistor and an upper color filter substrate including a color filter are prepared (st1).

The thin film transistor substrate is formed by repeating the process of depositing and patterning a thin film several times. The color filter substrate distinguishes each color filter and prevents light leakage occurring in portions other than the pixel region. This is achieved by sequentially forming green (G), blue (B) color filters, and a common electrode.

Next, an alignment film for determining the initial alignment direction of the liquid crystal molecules is formed on each substrate (st2).

In general, a polyimide-based organic material is mainly used for the alignment layer, and a rubbing method is used as a method of arranging the alignment layer.

Next, a seal pattern is formed on one of the two substrates (st3), and the seal pattern forms a gap for injecting the liquid crystal and prevents leakage of the injected liquid crystal.

Subsequently, in order to maintain a precise and uniform spacing between the upper substrate and the lower substrate of the liquid crystal display device, either one of the two substrates is dispersed (st4).

Next, two substrates of the liquid crystal display, that is, the thin film transistor substrate and the color filter substrate, are disposed, and the seal patterns are pressed and cured (st5).

Next, the liquid crystal is injected between the two substrates (st6).

When the injection of the liquid crystal is completed, the injection hole is sealed so that the liquid crystal does not flow out of the injection hole of the cell.

The liquid crystal panel is completed by manufacturing a liquid crystal cell and attaching polarizers to the outside of the liquid crystal cell, and then connecting the driving circuits.

However, in this case, misalignment may occur in the process of disposing the substrate so that the pixel electrode and the color filter correspond one-to-one, and a defect such as light leakage may occur when driving the liquid crystal display. In order to prevent this, the width of the black matrix of the upper substrate may be widened. In this case, the aperture ratio of the liquid crystal display becomes low.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems, and an object of the present invention is to provide an array substrate for a liquid crystal display device and a method of manufacturing the same, which have a high aperture ratio and can prevent defects.

1 is a cross-sectional view of a general liquid crystal display device.

2 is a flowchart illustrating a general liquid crystal cell process.

3 is a plan view of a liquid crystal display device according to the present invention;

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

5 is a cross-sectional view taken along line C-C in FIG. 3, showing a first embodiment of the present invention.

6 is a cross-sectional view of a liquid crystal display according to a second embodiment of the present invention.

7A and 7B are cross-sectional views of a liquid crystal display according to a third embodiment of the present invention.

8 is a cross-sectional view of a liquid crystal display according to a fourth embodiment of the present invention.

9A and 9B are plan views showing a first black matrix according to a fourth embodiment of the present invention.

In the liquid crystal display device for achieving the above object, a first black matrix is formed on a first substrate, and a color filter is formed on the first black matrix and has a red, green, and blue color sequentially. . A flattening film having a flat surface is formed on the color filter, and a plurality of orthogonal gate wirings and data wirings are formed thereon. Next, a thin film transistor connected to the gate line and the data line is formed, and a pixel electrode to receive a signal from the thin film transistor is formed. A second substrate is spaced apart from the first substrate by a predetermined distance on the first substrate, and a second black matrix is formed on an inner surface of the second substrate and a portion corresponding to the thin film transistor and an outer portion of the second substrate. A transparent electrode for generating an electric field together with the pixel electrode is formed below the second black matrix, and a seal pattern overlapping the first and second black matrices is formed at an outer portion between the first substrate and the second substrate. The liquid crystal layer is injected into the seal pattern between the first and second substrates.

Here, the first black matrix overlapping the seal pattern may partially overlap the seal pattern.

In addition, the first black matrix overlapping the seal pattern may be formed in a stripe form or may be formed in a mosaic pattern.

Meanwhile, in the method of manufacturing the liquid crystal display according to the present invention, after the first black matrix is formed on the first substrate by including the first substrate, the red, green, and blue colors are sequentially formed on the first black matrix. To form a color filter consisting of. Subsequently, a planarization film having a flat surface is formed on the color filter, and a plurality of gate wires and data wires orthogonal to the planarization film are formed. Next, a thin film transistor connected to the gate line and the data line is formed, and a pixel electrode connected to the thin film transistor is formed. Next, after forming the second black matrix on the second substrate with the second substrate, a transparent electrode is formed on the second black matrix. Next, a seal pattern is formed on the outer periphery of any one of the first substrate and the second substrate, the first substrate on which the pixel electrode is formed and the second substrate on which the transparent electrode is formed are bonded together, and then the first and second substrates Inject the liquid crystal inside the seal pattern. Here, the seal pattern overlaps the first and second black matrices.

In this case, the first black matrix overlapping the seal pattern may partially overlap the seal pattern.

In addition, the first black matrix overlapping the seal pattern may have a stripe shape or a mosaic pattern.

As described above, the present invention uses a structure in which the color filter is disposed under the thin film transistor to increase the aperture ratio of the liquid crystal display, and to form a black matrix at a position where the seal pattern is formed on the lower substrate, thereby forming a black matrix between the lower substrate and the planarization layer. Adhesion can be improved.

Recently, a method of forming a color filter on an array substrate to prevent misalignment of an LCD and to improve an aperture ratio has been proposed. In this case, a color filter may be formed under the thin film transistor, which is called a thin film transistor on color filter (TOC) structure.

Hereinafter, a liquid crystal display of a thin film transistor on color filter structure according to an exemplary embodiment of the present invention will be described with reference to the accompanying drawings.

3 is a plan view of a liquid crystal display according to the present invention.

As illustrated in FIG. 3, the liquid crystal display includes a lower substrate 210 and an upper substrate 220 in which first and second regions I and II are defined. Although the first region I is a portion in which an image is represented, a thin film transistor, a pixel electrode, and a color filter, which are elements for displaying an image, are formed in the first region I of the lower substrate 210. In the second region II, a pad 230 is formed to be connected to an external driving circuit to apply an image signal to an element of the first region I. A black matrix (not shown) and a common electrode (not shown) are formed in the first region I of the upper substrate 220, and the black matrix is formed at a position corresponding to the thin film transistor of the lower substrate 210. It is. In addition, the black matrix is formed in the second region II to surround the first region I in order to prevent leakage of light outside the image display region. The upper substrate 220 is smaller than the lower substrate 210 to expose the pads 230 formed on the lower substrate 210. Meanwhile, a seal pattern 240 is formed in the second region II between the upper and lower substrates 220 and 210, and the seal pattern 240 overlaps the black matrix of the upper substrate 220. A liquid crystal layer (not shown) is injected into the seal pattern 240, that is, the first region I, between the substrates 210 and 220.

FIG. 4 is a cross-sectional view of a liquid crystal display according to an exemplary embodiment of the present invention and illustrates a portion corresponding to one pixel in the first region of FIG. 3.

As shown in FIG. 4, a first black matrix 311 is formed on the transparent first substrate 310, and red (R) and green (G) bordering on the first black matrix 311 are formed thereon. ), Blue (B) color filters 312 are formed, respectively. In this case, the first black matrix 311 may be formed of a material that blocks light, and a metal material having good adhesion to the substrate 310 may be used.

Next, a planarization film 313 made of an organic material is formed on the color filter 312. Here, the planarization film 313 is to eliminate the step caused by the color filter and to facilitate the subsequent process.

Next, the gate electrode 321 is formed of a conductive material such as metal on the planarization layer 313, and the gate electrode 321 is connected to a gate wiring (not shown). A gate insulating film 330 made of a silicon nitride film or a silicon oxide film is formed on the gate electrode 310 to cover the gate electrode 321.

An active layer 341 made of amorphous silicon is formed on the gate insulating layer 330 on the gate electrode 321, and ohmic contact layers 351 and 352 made of amorphous silicon doped with impurities are formed thereon.

Source and drain electrodes 361 and 362 are formed on the ohmic contact layers 351 and 352 to face each other with respect to the gate electrode 321, and the source and drain electrodes 361 and 362 are formed on the gate electrode 321. Together to form a thin film transistor. The source electrode 361 is connected to a data line (not shown) that defines a pixel area orthogonal to the gate line.

Subsequently, a passivation layer 370 made of a silicon nitride film, a silicon oxide film, or an organic insulating layer is formed on the source and drain electrodes 361 and 362, and the passivation layer 370 is a contact hole 371 exposing the drain electrode 362. Has

Next, a pixel electrode 381 made of a transparent conductive material is formed in the pixel area above the passivation layer 370, and the pixel electrode 381 is connected to the drain electrode 362 through the contact hole 371.

Meanwhile, a second substrate 410 is disposed on the first substrate 310 and spaced apart from the first substrate 310 at a predetermined interval, and a second black matrix is formed on the inner surface of the second substrate 410. A 420 is formed and a common electrode 430 made of a transparent conductive material is formed under the 420. Here, the second black matrix 420 prevents external light from entering the channel of the thin film transistor to prevent the generation of photo current, and the second black matrix 420 is located only at a position corresponding to the thin film transistor. Can be formed.

The liquid crystal layer 500 is injected between the two substrates 310 and 410.

Although not shown, an alignment layer is formed on the pixel electrode 381 and the protective layer 370, and the lower portion of the common electrode 430, respectively, and the alignment layer is arranged in a predetermined direction so that initial alignment of liquid crystal molecules of the liquid crystal layer 500 is performed. Determine.

As described above, since the color filter is formed on the lower substrate, misalignment of the color filter and the pixel electrode does not occur when the upper substrate and the lower substrate are bonded together, and the black matrix of the upper substrate may be formed only on the thin film transistor. The aperture ratio can be improved.

Meanwhile, FIG. 5 corresponds to a cross section taken along line C-C in FIG. 3 and illustrates a portion where a seal pattern is formed.

As shown in FIG. 5, a planarization film 313 is formed on the entire surface of the lower substrate 310, and elements D for displaying an image are formed in the first region I thereon. A second black matrix 420 is formed below the second region II of the upper substrate 410, which is disposed at a predetermined distance from the lower substrate 310. Although not shown, the second black matrix 420 is formed. It is also formed in the first region I. The common electrode 430 is formed on the entire surface of the substrate 410 under the second black matrix 420. The seal pattern 450 is formed in the second region II between the upper substrate 410 and the lower substrate 310, so that the seal pattern 450 overlaps the second black matrix 420.

However, the flattening film 313 and the lower substrate 310 do not have good adhesion, and in particular, the gas is transferred to the outer contact portion ('E' in FIG. 5) of the lower substrate 310 and the flattening film 313 having weak adhesive strength. Can be introduced. This causes the gap between the planarization layer 313 and the lower substrate 310 or bubbles to be formed between the planarization layer 313 and the lower substrate 310, causing the seal pattern 450 to burst. As a result, a defect occurs when the liquid crystal is injected between the two substrates 310 and 410.

In order to prevent this, in the second embodiment of the present invention, a first black matrix is formed under the seal pattern.

6 is a sectional view showing a second embodiment of the present invention.

As shown in FIG. 6, the lower substrate 310 and the upper substrate 410 are disposed at regular intervals, and a first black matrix 311 is formed in the second region II of the lower substrate 310. It is. The planarization film 313 is formed over the entire surface of the substrate 310, and the elements D for displaying an image are formed in the first region I above the planarization film 313. The upper substrate 410 is disposed on the lower substrate 310 at regular intervals, and a second black matrix 410 is formed in the second region II of the inner surface of the upper substrate 410. Below the common electrode 430 is formed over the entire surface of the substrate 410, the seal pattern 450 is formed between the two substrates 310, 410 of the second region (II) to form the first and second It overlaps with the black matrices 311 and 420.

Here, the first black matrix 311 is made of a metal material, which is excellent in adhesion not only to the substrate 310 but also to the planarization layer 313. Therefore, even if the gas is introduced through the outer contact portions of the lower substrate 310 and the planarization layer 313, the first black matrix 311 blocks the penetration of the inside of the substrate 310 so that the seal pattern 450 may be formed. The bursting phenomenon can be prevented and a defect can be prevented during the liquid crystal injection.

Meanwhile, in FIG. 6, the first black matrix 311 and the seal pattern 450 are completely overlapped, but only a part of the first black matrix 311 may be overlapped.

A third embodiment of this invention is shown in Figs. 7A and 7B.

FIG. 7A illustrates that a right portion of the first black matrix 311 and a left portion of the seal pattern 450 overlap each other, and FIG. 7B illustrates a portion of the left portion of the first black matrix 311 and the seal pattern 450. It is shown that the right portion of the formed to overlap.

Next, a cross-sectional view of the liquid crystal display according to the fourth exemplary embodiment of the present invention is illustrated in FIG. 8.

As shown, the seal pattern 450 overlaps the first black matrix 311 of the lower substrate 310 and the second black matrix 420 of the upper substrate 410. Consists of a number of patterns. This may occur between the first black matrix 311 and the thin film transistor (not shown) positioned on the lower substrate 310 of the first region I because the first black matrix 311 is formed of a metal material. In order to reduce parasitic capacitance, the first black matrix 311 may be formed in various forms.

The shape of the first black matrix 311 is illustrated in FIGS. 9A and 9B. As illustrated, the first black matrix 311 may have a stripe shape or may have a mosaic pattern.

The present invention is not limited to the above embodiments, and various changes and modifications can be made without departing from the spirit of the present invention.

In the liquid crystal display according to the present invention, in order to improve the aperture ratio of the liquid crystal display using a TOC structure in which a color filter is formed under the thin film transistor, a black matrix is formed on the lower substrate at the position where the seal pattern is formed and a planarization film is formed thereon. By improving the adhesion between the planarization film and the substrate, it is possible to prevent the seal pattern burst phenomenon and to prevent defects during the liquid crystal injection.

Claims (8)

A first substrate; A first black matrix formed on the first substrate; A color filter forming a boundary on the first black matrix and having red, green, and blue colors sequentially; A planarization film covering the color filter and having a flat surface; A plurality of gate lines and data lines formed on the planarization layer and orthogonal to each other; A thin film transistor connected to the gate line and the data line; A pixel electrode receiving a signal from the thin film transistor; A second substrate spaced apart from the first substrate at a predetermined interval on the first substrate; A second black matrix formed on an inner surface of the second substrate and positioned at a portion corresponding to the thin film transistor and an outer portion of the second substrate; A transparent electrode formed under the second black matrix and generating an electric field together with the pixel electrode; A seal pattern positioned at an outer portion between the first substrate and the second substrate and overlapping the first and second black matrices; A liquid crystal layer injected into the seal pattern between the first and second substrates Liquid crystal display comprising a. The method of claim 1, And the first black matrix overlapping the seal pattern partially overlaps the seal pattern. The method of claim 1, The first black matrix overlapping the seal pattern has a stripe shape. The method of claim 1, The first black matrix overlapping the seal pattern has a mosaic pattern. Providing a first substrate; Forming a first black matrix on the first substrate; Forming a color filter forming a boundary on the first black matrix and having red, green, and blue colors sequentially; Forming a planarization film having a flat surface on the color filter; Forming a plurality of gate lines and data lines perpendicular to the planarization layer; Forming a thin film transistor connected to the gate line and the data line; Forming a pixel electrode connected to the thin film transistor; Providing a second substrate; Forming a second black matrix on the second substrate; Forming a transparent electrode on the second black matrix; Forming a seal pattern on an outer periphery of one of the first substrate and the second substrate; Bonding the first substrate on which the pixel electrode is formed and the second substrate on which the transparent electrode is formed; Injecting liquid crystal into the seal pattern between the first and second substrates Including, And the seal pattern overlaps the first and second black matrices. The method of claim 5, The first black matrix overlapping the seal pattern may be formed so as to overlap only a part of the seal pattern. The method of claim 5, The first black matrix overlapping the seal pattern has a stripe shape. The method of claim 5, The first black matrix overlapping the seal pattern has a mosaic pattern.