KR20060121554A - Color filter substrate and liquid crystal display of using the same - Google Patents

Abstract

A color filter substrate and an LCD using the same are provided to prevent the contamination of a liquid crystal layer due to the presence of color filters, by forming the color filters on a lower surface of the color filter substrate. A transparent conductive layer(124) is formed on one surface of a substrate(120). A color filter layer(122) is formed on the other surface of the substrate. The color filter layer includes three types of color filters alternately disposed, wherein the thicknesses of the color filters are uniform. A black matrix(121) is formed on the surface where the transparent conductive layer is formed. The black matrix shields the transmittance of light at regions overlapping boundary portions between different color filters.

Description

Color filter substrate and liquid crystal display using the same {Color Filter Substrate and Liquid Crystal Display of Using the Same}

1 is a plan view of a typical liquid crystal display device;

FIG. 2 is a cross-sectional view taken along the line AA ′ of FIG. 1;

3 is a cross-sectional view of a liquid crystal display device using a color filter substrate according to an embodiment of the present invention;

4A to 4G are cross-sectional views illustrating a method of manufacturing a color filter substrate according to an exemplary embodiment of the present invention.

♧ explanation of symbols for main parts of drawing

110-Thin Film Transistor Board 112-Data Line

114-pixel electrode 115-gate insulating film

116-Protective film 120-Color filter substrate

121-Black Matrix 122-Color Filter Layer

124-Common Electrodes 130-Liquid Crystals

The present invention relates to a color filter substrate and a liquid crystal display device using the same. More particularly, the present invention relates to a color filter substrate which solves a problem of visibility due to liquid crystal contamination by a color filter layer and a step of the color filter layer.

In general, a flat panel display (FPD) is a display device that provides a thin and flat screen, and is typically used as a liquid crystal display device (LCD) or a large digital TV that is widely used as a notebook computer monitor. Such as organic light emitting displays (OELDs) used in plasma displays (PDPs) or mobile phones.

The liquid crystal display device transfers an image by converting an input electric signal into visual information by using a characteristic in which light transmittance of a liquid crystal, which is an intermediate state material between a liquid and a crystal, changes according to an applied voltage. A typical liquid crystal display device is composed of two substrates provided with electrodes and a liquid crystal injected between the substrates. Different voltages are applied to the two substrates to apply an electric field to the liquid crystal. At this time, the arrangement of the liquid crystal molecules is changed to change the light transmittance. Such liquid crystal displays have been widely used in recent years because they are lighter in weight, smaller in volume, and operate with smaller power than other display apparatuses having the same screen size.

1 is a plan view of a typical liquid crystal display device.

Referring to FIG. 1, the LCD includes a thin film transistor substrate 10, a color filter substrate 20, and a liquid crystal (not shown) injected therebetween. In the thin film transistor substrate 10, a plurality of gate lines 11 and data lines 12 cross each other horizontally and vertically, and each cross region corresponds to a pixel region, and the thin film transistor 13 and the pixel electrode are formed. 14 is provided. The color filter substrate 20 is provided with a common electrode 24 corresponding to the pixel electrode 14. Although not shown in the drawing, the color filter substrate 20 is formed with a color filter for realizing color.

A schematic operation of the liquid crystal display device configured as described above is as follows. First, when the gate-on signal is applied to the gate line 11 and the thin film transistor 13 is turned on, the data voltage of the data line 12 is applied to the pixel electrode 14 through the thin film transistor 13. In this case, a reference voltage is applied to the common electrode 24, and the arrangement of liquid crystal molecules is changed by an electric field corresponding to the voltage difference applied to the pixel electrode 14 and the common electrode 24.

FIG. 2 is a cross-sectional view taken along the line AA ′ of FIG. 1.

Referring to FIG. 2, two insulating layers 15 and 16 are formed on the thin film transistor substrate. The bilayer insulating films 15 and 16 comprise a gate insulating film 15 covering the gate electrode of the thin film transistor, and a protective film 16 for protecting the thin film transistor, and are usually formed of a silicon nitride film. The data line 12 is formed in a predetermined region on the gate insulating layer 15, and the pixel electrode 14 is formed on the passivation layer 16.

On the other hand, on the color filter substrate 20, the color filter layer 22 and the common electrode 24 for color implementation are provided. The color filter layer 22 is typically formed by alternating layers representing three different colors corresponding to three primary colors of light, and red and green color layers R and G are illustrated in the drawing. In addition, a black matrix 21 is formed at a boundary portion where the different color layers R and G are adjacent to each other. The black matrix 21 serves to block light that passes through the liquid crystal in a portion not controlled by the pixel electrode 24. An overcoat 23 and a common electrode 24 are formed on the black matrix 21 and the color filter layer 22. The planarization layer 23 may exhibit excellent step coverage during deposition of the common electrode 24 despite the bending formed on the color filter substrate 20 by the black matrix 21 and the color filter layer 22. It is optional and not required. The common electrode 24 corresponds to the pixel electrode 14 on the thin film transistor substrate 10. The liquid crystal 30 is injected between the thin film transistor substrate 10 and the color filter substrate 20, and the liquid crystal 30 is formed according to the voltage applied to the common electrode 24 and the pixel electrode 14. The arrangement direction is changed by the electric field.

The conventional liquid crystal display having the above structure has a problem associated with the color filter layer 22. Specifically, the liquid crystal 30 may be contaminated by the color filter layer 22 to generate an afterimage. When the common electrode 24 is formed, an alignment layer (not shown) is formed on the color filter substrate 20 in a subsequent process. The alignment layer is for arranging molecules of the liquid crystal 30 in one direction, and is formed through a cleaning / printing / drying / baking process. However, during the baking process, the substrate is heated at 220 ° C. for about 1 hour. At this time, some materials constituting the color filter layer 22 move through the common electrode 24 to contaminate the alignment layer. For this reason, the liquid crystal 30 injected between the color filter substrate 20 and the thin film transistor substrate 10 is contaminated in a subsequent process, and the contamination of the liquid crystal 30 causes spots or residual images on the screen.

In addition to contaminating the liquid crystal 30 as described above, the visibility problem may be caused by the color filter layer 22. The width between the color filter substrate 20 and the thin film transistor substrate 10 is generally referred to as a cell gap, which affects contrast ratio / viewing angle / brightness uniformity. However, there is a variation in thickness in the color filter layer 22, and the cell gap cannot be kept constant due to the variation in the thickness of the color filter layer 22. There are various causes of the color filter layer 22 having a deviation, such as a limitation in manufacturing technology or a case where a minute deviation exists in the substrate 20 itself on which the color filter layer 22 is formed. Also, as shown in FIG. 2, the color filter layer 22 is formed stepwise on the color filter substrate 20 and the black matrix 21 having different heights, and different color layers constituting the color filter layer 22. A separate photolithography process may be performed on each of the (R and G) layers, and the color filter layer 22 may not have a uniform thickness but may have a deviation.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a color filter substrate which forms a color filter layer with a uniform thickness and prevents liquid crystal contamination by the color filter layer. Another object of the present invention is to provide a method of manufacturing the color filter substrate and a liquid crystal display device using the color filter substrate.

In order to achieve the above technical problem, the present invention provides a color filter substrate. The color filter substrate is characterized in that both surfaces of the substrate are used simultaneously. That is, in the present invention, the common electrode, which is a transparent conductive layer, is formed on one surface of the color filter substrate by utilizing both surfaces of the substrate, and the color filter layer is formed on the opposite surface.

 The color filter substrate is bonded to a thin film transistor substrate, which is another substrate with a liquid crystal interposed therebetween, wherein a surface facing the thin film transistor substrate is called an inner surface and an opposite surface is an outer surface, and the color filter layer is an outer surface of the color filter substrate. To be formed. The color filter layer may act as a source that causes various problems, such as contaminating the liquid crystal or making the gap between the color filter substrate and the thin film transistor substrate uneven. However, in the present invention, by separately forming the color filter layer on the outer surface of the color filter substrate, it is possible to fundamentally block the contamination of the liquid crystal.

In the color filter layer, color layers representing three different colors are alternately arranged. In addition, a black matrix that blocks light transmission to an inner surface of the color filter substrate is formed in an area overlapping a boundary portion where the different color layers contact each other. Conventionally, the color filter layer is formed on the inner surface of the color filter substrate on the black matrix, but in the present invention, the color filter layer is formed on the outer surface of the substrate which is flat because there is no black matrix. For this reason, each color layer which comprises a color filter layer can all be formed in uniform thickness.

In order to manufacture the color filter substrate having the above structure, the process must be performed on both sides of the substrate, so that the process on one side is completed and then the process on the opposite side. There is no restriction on which side to proceed first. Therefore, in the case where the surface on which the color filter layer is formed is later formed, a common electrode including a black matrix and a transparent conductive layer is formed in a predetermined region on one surface of the color filter substrate, and then the color filter layer is formed on the opposite surface of the color filter substrate. Alternatively, the color filter layer may be first formed on one surface of the color filter substrate, and then the black matrix and the common electrode may be formed on the opposite surface of the color filter substrate.

Meanwhile, the liquid crystal display device may be manufactured using the color filter substrate. The liquid crystal display device includes a thin film transistor substrate and a color filter substrate bonded to upper and lower portions of the liquid crystal so as to face the liquid crystal, and a voltage for applying an electric field to the liquid crystal is applied to the thin film transistor substrate and the color filter substrate. The pixel electrode and the common electrode are formed to face each other, and a color filter layer representing color is formed on the color filter substrate on the opposite side on which the common electrode is formed.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, the present invention is not limited to the embodiments described herein and may be applied and modified in various forms. Rather, the following embodiments are provided to clarify the technical spirit disclosed by the present invention, and furthermore, to fully convey the technical spirit of the present invention to those skilled in the art having an average knowledge in the field to which the present invention belongs. Therefore, the scope of the present invention should not be construed as limited by the embodiments described below. In addition, in the drawings presented in conjunction with the following examples, the size of layers and regions are simplified or somewhat exaggerated to emphasize clarity, and like reference numerals in the drawings indicate like elements.

The present invention is characterized in that the vertical structure of the substrate and in plan view does not differ from the conventional structure of Figure 1, looks at the detailed structure as a vertical cross-sectional view. In addition, the present invention relates to a color filter substrate, but may be applied to a liquid crystal display device using the same, and thus, a thin film transistor substrate and a liquid crystal will be described. FIG. 3 is a cross-sectional view illustrating a structure of a liquid crystal display device using a substrate according to an exemplary embodiment of the present invention, taken along line AA ′ of FIG. 1.

Referring to FIG. 3, the liquid crystal display includes a thin film transistor substrate 110, a color filter substrate 120, and a liquid crystal 130. In the thin film transistor substrate 110, two insulating layers 115 and 116 are formed on a transparent glass substrate. The two-layer insulating films 115 and 116 correspond to the gate insulating film 115 and the protective film 116, which are usually formed of a silicon nitride film. A thin film transistor (not shown) is provided on the thin film transistor substrate 110. The gate insulating layer 115 is formed to cover the gate electrode of the thin film transistor, and the passivation layer 116 is formed to protect the thin film transistor and the like. Is formed. A data line 112 is formed in a predetermined region on the gate insulating film 115, and the data line 112 is a boundary of a pixel. The pixel electrode 114 is formed on the passivation layer 116, and one pixel electrode 114 is provided for each pixel bordering the data line 112.

The color filter substrate 120 is bonded to face the thin film transistor substrate 110, and the liquid crystal 130 is injected and sealed between the thin film transistor substrate 110 and the color filter substrate 120. The common electrode 124 and the color filter layer 122 are formed on the color filter substrate 120. The common electrode 124 is applied with a voltage along with the pixel electrode 114 and operates to change the arrangement direction of the liquid crystal 130. Therefore, the common electrode 124 and the pixel electrode 114 are transparent conductive layers through which light can pass, and are commonly formed of indium tin oxide or zinc indium oxide. On the other hand, the color filter layer 122 is installed so as to represent the color is formed by alternately arranged layers representing three different colors corresponding to the three primary colors of light, the color layer (R, G) of the red and green in the drawing Is shown. The color filter layer 122 is formed on an opposite surface on which the common electrode 124 is formed on the color filter substrate 120. For convenience of description, a surface on which the common electrode 124 is formed in the color filter substrate 120 is called an inner surface, and a surface on which the color filter layer 122 is formed is an external surface. The color filter layer 122 is formed. Conventionally, only the inner surface of the color filter substrate 120 is used to form the color filter layer 122 and the common electrode 124 on the inner surface, and the outer surface of the color filter substrate 120 is not used separately. In contrast, the present invention solves the problems of the conventional structure by extending the application range of the color filter substrate 120 to the outer surface, and looks at the effects of the present invention in detail.

As described above, according to the related art, problems such as nonuniformity of the cell gap, which is a gap between the thin film transistor substrate 110 and the color filter substrate 120, and contamination of the liquid crystal are generated. The above problem is caused by forming components having different functions, such as the color filter layer 122 or the common electrode 124, by concentrating only on one side of the color filter substrate 120, thereby acting on each other. In view of this, in the present invention, each component is formed by separating the color filter substrate 120 by using both the inner and outer surfaces of the color filter substrate 120. That is, by using the color filter substrate 120 as a kind of blocking film, components formed on the inner surface of the color filter substrate 120 and components formed on the outer surface of the color filter substrate 120 are unnecessary. To prevent interaction.

In detail, the color filter layer 122 formed on the inner surface of the color filter substrate 120 may be formed on the outer surface of the color filter substrate 120 as shown in FIG. 3. In general, an alignment layer (not shown) is formed on the color filter substrate 120 to align the liquid crystal molecules in one direction, and undergoes a baking process at a high temperature in forming the alignment layer. In this case, some materials may be separated from the color filter layer 122 by the high temperature. If the color filter layer 122 is formed on the inner surface of the color filter substrate 120 as in the related art, a material separated from the color filter layer 122 may move through the common electrode 124 and contaminate the alignment layer. However, under the structure of the present invention, the color filter substrate 120 may block the movement of the material separated from the color filter layer 122. Contamination of the alignment layer leads to contamination of the liquid crystal 130, resulting in deterioration of image quality, but according to the present invention, contamination of the liquid crystal 130 may be blocked at the source.

As described above, the advantages of the structure of separating the color filter layer 122 from the color filter substrate 120 separately from the common electrode 124 and the like are various in addition to preventing contamination of the liquid crystal 130. For example, in the patterned vertically aligned (PVA) mode to solve the viewing angle problem of the liquid crystal 130, a photolithography process is added to the common electrode 124 to form a cutout pattern. The color filter layer 122 may be damaged or the cutout may be exposed to alter physical properties of the liquid crystal 130. However, if the color filter layer 122 is separated by the color filter substrate 120, the above problem may be solved.

Another advantage of the structure of forming the color filter layer 122 on the outer surface of the color filter substrate 120 is that the cell gap between the color filter substrate 120 and the thin film transistor substrate 110 can be kept constant. As described above, if the cell gap is not constant, the screen is not uniform as a whole and the visibility is different. The cell gap is affected by all the components formed on the inner surface of the color filter substrate 120 and the thin film transistor substrate 110. For example, if the color filter layer 122 or the common electrode 124 formed on the color filter substrate 120 is not formed to have a uniform thickness, such nonuniformity may be reflected and the cell gap may not be kept constant. However, any component formed on the outer surface of the color filter substrate 122 does not affect the cell gap. Therefore, simply forming the color filter layer 122 on the outer surface of the color filter substrate 120, even if there is a deviation in the thickness of the color filter layer 122 can maintain a constant cell gap irrespective of it.

As shown in FIG. 3, a black matrix 121 is formed on an inner surface of the color filter substrate 120. The black matrix 121 is installed at a boundary portion of each pixel to block light passing through the liquid crystal in a portion not controlled by the pixel electrode 114. If the color filter layer 122 is formed on the inner surface of the color filter substrate 120 as in the related art, the color filter layer 122 is formed stepped by the black matrix 121. In this case, as shown in FIG. 2, it is not easy to form the color filter layer 122 so as to maintain a uniform thickness between a portion in contact with the color filter substrate 120 and a portion in contact with the black matrix 121. On the other hand, as shown in FIG. 3, when the color filter layer 122 is formed on the outer surface of the color filter substrate 120, there is no factor causing a step like the black matrix 121, and thus the color filter layer 122 having a uniform thickness is easily formed. ) Can be formed. The black matrix 121 and the color filter layer 122 are formed by being separated into an outer surface and an inner surface of the color filter substrate 120, but the black matrix 121 is a color layer constituting the color filter layer 122 ( It is located in an area overlapping the boundary portion of R, G).

Hereinafter, a method of manufacturing a color filter substrate having a structure in which a color filter layer and a common electrode are formed on an opposite surface of the substrate will be described.

4A to 4G are cross-sectional views illustrating a method of manufacturing a color filter substrate according to an exemplary embodiment of the present invention. In this regard, the thin film transistor is manufactured separately from the color filter substrate, and thus, a drawing and a description of the thin film transistor will be omitted unlike in FIG. 3.

Referring to FIG. 4A, first, a black matrix 121 is formed on one surface of a transparent insulating substrate 120 such as a glass material. As the material of the black matrix 121, a metal thin film such as chromium (Cr) or an organic material of carbon system is mainly used, and chromium (Cr) / chromium oxide (CrO _X ) is used to lower the surface reflectivity of the screen. The dual structure of can be applied. In this case, when the chromium / chromium oxide film is deposited by sputtering or the like and then a predetermined region of the chromium / chromium oxide film is continuously removed by a photolithography process, a low reflection black matrix 121 is formed.

Referring to FIG. 4B, a common electrode 124 is formed on the black matrix 121 and the color filter substrate 120. The common electrode 124 may be formed of indium tin oxide or indium zinc oxide by sputtering or the like. Although not illustrated, a planarization layer may be interposed between the black matrix 121 and the common electrode 124. The planarization layer is selectively used to exhibit excellent step coverage during deposition of the common electrode 124 in a state where the color filter substrate 120 is bent by the black matrix 121 or the like. However, in the present invention, since only the black matrix 121 except for the color filter layer 122 is formed on the color filter substrate 120, the bending degree of the color filter substrate 120 is not severe, so that the flattening film is less than the conventional method. The need is somewhat reduced.

 4C to 4G, the color filter layer 122 is formed on the color filter substrate 120 in the opposite direction in which the black matrix 121 and the common electrode 124 are formed. The color filter layer 122 is formed by alternately arranging color layers R, G, and B representing three different colors, and the color layers R, G, and B are red / green /, which are three primary colors of light. It consists of a colored layer of blue. The color layers R, G, and B are made of photoresist including red, green, and blue pigments, and are typically a red layer (R), a green layer (G), and a blue layer (B) using a photolithography process. And the black matrix 121 is positioned at the boundary between the color layers R, G, and B.

Specifically, as shown in FIG. 4C, the red photoresist film 127 is formed using a spin method or the like. The spin method has a high photoresist consumption but has an excellent thickness uniformity. Subsequently, the color filter substrate 120 having the red photoresist film 127 is exposed to the light passing through the mask. In general, a negative photoresist is used as the photoresist. In this case, when the development process is performed, a portion not exposed to light is removed and a red layer R remains as shown in FIG. 4D. Thereafter, the baking process is performed to allow the red layer R to adhere onto the color filter substrate 120. Subsequently, a green photoresist film 128 is formed on the color filter substrate 120 on which the red layer R is formed. The green photoresist film 128 is formed stepped on the color filter substrate 120 by the red layer R as shown in FIG. 4E. Subsequently, when the photolithography process is performed on the green photoresist film 128, the green layer G as shown in FIG. 4F is formed, and the same process is repeated to form the blue layer B as shown in FIG. 4G.

The color filter substrate illustrated in FIG. 3 utilizes both sides of the substrate, and separates a specific component from one side of the substrate, thereby blocking a passage that may cause a problem by the specific component by the substrate. will be. Specifically, although the embodiment of the present invention discloses a structure in which the color filter layer is separated from the outer surface of the color filter substrate, the same may be applied to other components. Meanwhile, in manufacturing the color filter substrate having the structure of FIG. 3, the process for one side may be performed and then the process for the other side may be performed, and there is no particular limitation as to which side to proceed first. Therefore, in the process illustrated in FIGS. 4A to 4E, although the black matrix and the common electrode are formed on one surface of the color filter substrate, the color filter layer is formed on the opposite surface. However, the process may be performed in the reverse order. That is, after forming the color filter layer in the order of the red layer, the green layer, and the blue layer on one surface of the color filter substrate, the black matrix and the common electrode may be formed on the opposite surface. Of course, in addition to the above method, there are various methods of manufacturing the color filter substrate having the structure shown in FIG.

As described above, according to the present invention, the color filter substrate and the liquid crystal display device using the same can solve various problems when various components are concentrated on one name of the color filter substrate by simultaneously using both surfaces of the color filter substrate. Can be. In other words, if the color filter layer is formed separately on one side of the color filter substrate, it is possible to prevent the liquid crystal from being contaminated by the color filter layer, and even if the thickness of the color filter layer is somewhat non-uniform, the color filter substrate and the thin film transistor are uniform. You can maintain the interval.

Claims (8)

Board; A transparent conductive layer formed on one surface of the substrate; And a color filter layer formed on an opposite surface of the substrate. The method of claim 1, The color filter layer may be formed by alternately arranging color layers representing three different colors, and the color layer is formed to have a uniform thickness. The method of claim 2, And a black matrix blocking light transmission in a region overlapping a boundary portion where the different color layers contact each other, on the substrate in the direction in which the transparent conductive layer is formed. Forming a black matrix blocking light transmission in a predetermined region on one surface of the substrate; Depositing a conductive film on the substrate and the black matrix to form a transparent conductive layer; Forming a color filter layer comprising three different color layers alternately arranged on opposite sides of the substrate. Forming a color filter layer having three different color layers alternately arranged on one surface of the substrate; Forming a black matrix blocking light transmission in a predetermined area on an opposite surface of the substrate; And depositing a conductive film on the substrate and the black matrix to form a transparent conductive layer. A liquid crystal and a thin film transistor substrate and a color filter substrate bonded to upper and lower portions of the liquid crystal to face each other, On the thin film transistor substrate and the color filter substrate, a pixel electrode and a common electrode to which a voltage for applying an electric field to the liquid crystal are applied are formed to face each other. And a color filter layer showing color on the color filter substrate on the opposite side of the common electrode. The method of claim 6, The color filter layer is formed by alternating color layers representing three different colors, wherein the color layers are formed to have a uniform thickness. The method of claim 7, wherein And a black matrix is formed on the color filter substrate in the direction in which the common electrode is formed to block light transmission in a region overlapping a boundary portion where the different color layers contact each other.

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