KR101250236B1 - Fabrication method for color filter substrate and liquid crystal display device having thereof - Google Patents

Abstract

According to an exemplary embodiment of the present invention, a method of preparing a liquid crystal display device includes preparing a first substrate on which a thin film transistor is formed, preparing a second substrate on which a color filter is formed, and forming a liquid crystal layer between the first substrate and the second substrate. It is configured to include. In this case, the forming of the second substrate may include forming a black matrix on a substrate, forming a color filter on a portion of the second substrate by a photolithography process, and simultaneously forming a color filter on the remaining portion of the second substrate. Forming a color filter by a method of roll printing the filter forming ink.

Color filters, photolithography, roll printing

Description

A color filter substrate and a manufacturing method of a liquid crystal display device including the same {FABRICATION METHOD FOR COLOR FILTER SUBSTRATE AND LIQUID CRYSTAL DISPLAY DEVICE HAVING THEREOF}

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

2A to 2D are cross-sectional views showing a method of forming a color filter by conventional photolithography.

3a to 3d and 4a to 4d are cross-sectional views schematically showing an embodiment according to the present invention.

5 is a cross-sectional view showing a color filter formed according to an embodiment of the present invention.

6a to 6e are schematic views of another embodiment showing the process of forming the color filter by the roll printing method of the present invention.

<Explanation of symbols for main parts of the drawings>

121: substrate 122: black matrix

123: the composition for color filter formation 123b, 223b: color ink

128: mask 132, 232: printing roll

134, 234

The present invention relates to a liquid crystal display device, and more particularly, to a method for manufacturing a color filter substrate of a liquid crystal display device that can simplify the process and reduce the manufacturing cost.

2. Description of the Related Art Recently, various portable electronic devices such as a mobile phone, a PDA, and a notebook computer have been developed. Accordingly, there is a growing need for a flat panel display device for a light and small size. Such flat panel displays include Liquid Crystal Display (LCD), Plasma Display Panel (PDP), Field Emission Display (FED), and Vacuum Fluorescent Display (VFD), but due to mass production technology, ease of driving means and high quality As a result, liquid crystal display (LCD) is in the spotlight.

1 schematically illustrates a cross section of a general liquid crystal display device. As shown in the figure, the liquid crystal display device 1 includes a liquid crystal layer 7 formed between the first substrate 5 and the second substrate 3 and between the first substrate 5 and the second substrate 3. It consists of. The first substrate 5 is a substrate on which a thin film transistor (TFT) 9 is mounted. Although not shown in the drawing, a plurality of pixels are formed on the substrate, and each pixel is driven like the thin film transistor 9. An element is formed. Therefore, the substrate is also referred to as a thin film transistor substrate. The second substrate 3 is a substrate on which a color filter (CF) 2 for realizing color is formed, and is configured to face the first substrate 5 with the liquid crystal layer 7 therebetween. The substrate is also called a color filter substrate. The substrate is formed with a black matrix (BM) 8 to block unnecessary light.

Further, pixel electrodes 6 and common electrodes 4 are formed on the first substrate 5 and the second substrate 3, respectively, and an alignment layer (not shown) for orienting liquid crystal molecules of the liquid crystal layer 7. This is applied and the orientation of liquid crystal molecules is determined.

The first substrate 5 and the second substrate 3 are bonded together with the liquid crystal layer 7 interposed therebetween, and the liquid crystal is driven by a driving element 9 represented by a thin film transistor formed on the first substrate 5. The information is displayed by driving the molecules to control the amount of light passing through the liquid crystal layer.

The method of manufacturing the above-described substrates is formed by another method, provided that the apparatus provided is different. The first substrate 5 includes a process of forming the thin film transistor 9 on the first substrate 5, and the second substrate 3 includes a process of forming the color filter 2.

The thin film transistor substrate process forms a plurality of gate lines and data lines defining pixel regions on a first substrate and forms a thin film transistor 9 connected to the gate lines and the data lines. do. At this time, the pixel electrode 6 is connected to the thin film transistor and drives the liquid crystal layer. The pixel electrode 6 drives the liquid crystal layer 7 as a signal is applied to the thin film transistor.

In addition, the color filter substrate process is performed by forming the black matrix 8 on the second substrate 3, forming the color filter 2 on the upper side thereof, and then forming the common electrode 4.

The method of manufacturing a color filter includes a pigment dispersion method and an electrodeposition method, among which a pigment composition is coated with a pigment composition dispersed in a photoresist (PR) by using a photolithography process. ), A method of forming a color filter by exposure, development and firing.

2 is a cross-sectional view showing a procedure for manufacturing a color filter by photolithography which is a conventional color filter forming process. Referring to this, first, as shown in FIG. 2A, a black matrix forming material such as chromium (Cr) or an organic material is coated on the substrate 21, and then the black matrix pattern 22 is formed by using a photolithography process. To form. Subsequently, as shown in FIG. 2B, a color filter forming composition 23 of any one of red, green, and blue colors (formed from red (R) in the drawing) is coated, and then a photomask; 28, only a predetermined area is exposed and then developed, to form a red color filter 23a as shown in FIG. 2C. Subsequently, instead of the red color filter forming composition, the above process is repeated using the green and blue color filter forming composition, as shown in FIG. 2D, and the green and blue color filters 23b and 23c. ), The red, green, and blue color filters 23 are produced.

However, the conventional method of manufacturing a color filter as described above has to use an expensive photomask, and the manufacturing cost increases because the photolithography process such as color filter coating, exposure, and development must be repeated. In addition, as the exposure is performed to an unintended area during exposure, a color filter is formed on the black matrix as shown in the drawing. As a result, the surface of the color filter may have a height where a portion of the black matrix is present higher than another portion (see FIG. 2D). That is, a step is formed on the surface, and the step is then first and second substrates. If the liquid crystal is injected and the liquid crystal is injected, it may cause a poor image quality. This phenomenon occurs because the amount of the liquid crystal formed between the first substrate and the second substrate is not constant. One of them is gravity failure and touch failure caused by the change of the liquid crystal. Therefore, conventionally, in order to solve such a problem, an overcoat film for planarizing the color filter surface has to be formed. Therefore, there is a disadvantage that the process of the color filter substrate is complicated.

In order to solve this problem, a roll printing method has been proposed. The roll printing method is a method in which film formation and patterning are simultaneously performed by pattern-coating a substance for forming a film on a substrate on a surface of a printing roll, and then rotating the printing roll on a first substrate at a constant pressure and speed. In addition, in order to improve the adhesion of the printing material and the accuracy of pattern formation, the roll printing method imparts a positive or negative property to the printing material and gives the opposite polarity to the object to be printed. The printing material could be transferred by force. Therefore, by applying the same to the color filter, it was possible to form red (R), green (G; Green) and blue (B; Blue) colors on the color filter substrate by roll printing in each pixel area.

However, when the manufacturing process of the color filter by the roll printing method is a cylindrical pattern that is not exactly the same as the substrate, it should ideally be printed on the substrate, but in the actual process, misalignment may appear during printing. There was. In addition, the boundary between red, green, and blue colors may not be clear at the time of printing, resulting in a mixture of red, green, and blue colors.

In order to solve the above problems, a liquid crystal display device may be manufactured by using a method of forming a color filter by photolithography and a roll printing method, thereby reducing the step in forming the color filter. In addition, it is easier to align the color filter than the roll filter alone, and the color filter formation time is shorter than the photolithography process, and the process is simplified and the defect is reduced by using relatively low cost equipment. Therefore, the object of the present invention is to provide a high quality liquid crystal display device by gaining time gain.

According to an exemplary embodiment of the present invention, a method of manufacturing a liquid crystal display device includes preparing a first substrate having a thin film transistor and a second substrate facing the thin film transistor, forming a color filter on the first substrate or the second substrate, and between the two substrates. It characterized by comprising a step of forming a liquid crystal layer. In this case, the forming of the color filter may include forming a black matrix on the substrate and forming at least one color filter on the substrate by a photolithography process, and in parallel with the ink for forming the color filter on the substrate. It characterized in that it comprises the step of forming a color filter of at least one color by a method of roll printing.

In the present invention, a color filter substrate is formed by using a photolithography process and a roll printing process in parallel. Therefore, by forming a part of the color filter using photolithography and performing the rest of the process by the roll printing or by changing the order to overcome the disadvantages of photolithography and roll printing and to secure the productivity advantage in terms of cost in time.

According to the present invention, one or two color filters of three colors of red, green, and blue can be formed by photolithography, and color filters of the remaining colors can be formed by roll printing. Therefore, according to the present invention, the value can be reduced by not forming some of the steps generated when the color filters of red, green, and blue are sequentially formed, which are a big problem of photolithography. This is because, when the color filter is formed by roll printing, printing in a patterned form is possible, so that the step is lower than in the case of photolithography.

When the color filter is formed only by photolithography according to the existing invention, it undergoes firing during the process, and as a result, a portion where the color filter and the black matrix overlap is fired to generate a step (see FIG. 2D). When the filter is formed, the photolithography and the roll printing method are performed in parallel as described above, and thus, the portion where the step is generated can be reduced.

In addition, in the embodiment of the present invention, there is an effect of reducing misalignment. When the color filter is formed only by printing, misalignment occurs easily due to the characteristics of the roll, but it can be reduced by forming a color filter in parallel with photolithography. In general, in the manufacturing process of the liquid crystal display device, an alignment key is formed to align the alignment, and accordingly, a subsequent process is performed. In the present invention, it is possible to form an alignment key with a black matrix at the same time as forming a black matrix for alignment in the manufacturing process of the liquid crystal display device, the alignment key is recognized by a recognition device such as a camera and then various Can be applied on the process.

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

In the conventional invention, it is common to form all the color filters of red, green, and blue of a pixel by using photolithography. However, in the present invention, at least one of red, green, and blue colors of the color filter is formed by photolithography, and the remaining portions are formed by roll printing.

3A to 3D and 4A to 4D are cross-sectional views schematically showing an embodiment according to the present invention.

First, a metal or resinous black matrix forming material layer for forming a black matrix is formed on a transparent substrate (FIG. 3A). In general, a black matrix is formed between red, green, and blue sub color filters, and has a first color matrix. The object of the present invention is to block light passing through a reverse tilt domain formed at a periphery of a pixel electrode formed on a substrate. As the material of the black matrix, a metal thin film such as chromium (Cr) is used or a photosensitive organic material is mainly used, and a double film such as chromium / chromium oxide (Cr / CrOx) may be used for the purpose of low reflection. When the metal thin film or the photosensitive organic material is used as the material of the black matrix, it may be formed in a predetermined pattern through a photolithography process (FIG. 3B).

As shown in FIG. 3C, the color filter forming composition 123 colored in one of red, green, and blue colors is applied to the entire surface including the black matrix 122 so as to completely cover the black matrix 122. do. Next, as shown in FIG. 3C, after exposing only a specific region of the upper portion of the color filter forming composition 123 applied using the mask 128, partial exposure is performed.

Next, as illustrated in FIG. 3D, the color filter forming composition 123 having the photochemical structure changed by exposure is dipped in a developing solution, and the developed photosensitive film is cured to form a color filter 123a. Usually, the composition for forming a color filter has a characteristic of a negative resist, and thus, an unexposed portion is removed, but the color filter may be formed of a positive resist.

One or two of the colors for forming the color filter are formed by the color filter by the photolithography method described above. In this case, as the existing color filter forming method, the above process is repeated using the same mask to form color filters of all colors. However, when the color filter is subsequently formed by photolithography, there is a problem such as a step in the black matrix portion, so that in the present invention, the color filter is formed by the method of roll printing.

Therefore, after some color filters are formed by photolithography, the color filters are formed by a roll printing method. 4A to 4D are exemplary embodiments schematically illustrating a method of forming a color filter by a roll printing method. Referring to the drawings, a method of forming the color filter by roll printing is as follows.

First, the ink supply container 131 is filled with the color ink 123b. Then, the ink supply container 131 filled with the color ink 123b is wetted so that the printing roll 132 is in contact with the ink supply container 131b. The color ink is filled (FIG. 4A). The printing roll 132 is then contacted and rotated on the cliché 134 in which the groove corresponding to the negative region of the color filter pattern to be formed is formed (FIG. 4B). A pattern is formed on the printing roll 132. (FIG. 4C) The patterned printing roll is printed on the substrate 121 on which the black matrix 122 is formed. (FIG. 4D).

5 is a cross-sectional view illustrating a case in which a color filter is formed by the photolithography and the roll printing method. As shown in the present embodiment, a substrate having a reduced level of black matrix portions may be manufactured.

The roll printing method may be various. 6A to 6E are schematic views of another embodiment showing a process of forming a color filter by a roll printing method. In the present embodiment, first, the ink supply container 231 is filled with the color ink 223b, and then the ink supply roll 236 is wetted so as to contact the ink supply container 231 filled with the color ink 223b, and then rotated. The color ink 223b is filled in the entire surface of the ink supply roll 236. (Fig. 6A) Next, the cliché 234 in which the groove 238 corresponding to the color filter pattern to form the ink supply roll 236 is formed. The color ink 223b is applied to the cliché 234 by rotating it in contact with the c) (Fig. 6B). Then, the surface of the cliché 234 is removed by using the color ink removal tool 237. By pushing it flat, the color ink 223b is filled in the groove 238 of the cliché and all the ink remaining on the surface is removed (FIG. 6C).

Thereafter, the printing roll 232 is rotated in contact with the surface of the cliché 234, the color ink 223b is transferred to the surface of the printing roll 232 (Fig. 6D), the printing roll 232 The color ink 223b transferred to the substrate is again transferred onto the substrate 121 to form a color filter, as shown in FIG. 6E. At this time, as the printing roll is rotated by contacting the color ink transferred to the surface to the substrate, a color filter is formed on the substrate.

In the second embodiment, two or more colors can be printed on the second substrate at one time. When the printing roll is rotated in contact with the surface of the first cleavage body showing one color, the color ink of one color is transferred, and when the printing roll is rotated in contact with the surface of the second cleat body, The color ink is transferred. Therefore, two or more color filters may be formed on the second substrate with one printing roll.

 The method for manufacturing the color filter substrate described above shows an embodiment according to the present invention. Therefore, the present invention is not limited to the above-described embodiments, and various changes may be made within the scope of the present invention.

For example, as described above, two color filters are formed through photolithography and one color filter is formed by roll printing, but one color and two color filters are formed by photolithography. May form. In any case, there is an effect that the step of the black matrix portion is reduced.

In the above description, the photolithography process is first performed, and then the roll printing is performed in the subsequent process, but according to the present invention, the order may be changed. Therefore, for example, one or two color filters may be formed by roll printing, and then color filters of the remaining colors may be formed by photolithography. In addition, as described above, the number of times of photolithography and roll printing may be variously changed. For example, one color filter and two photolithography, one photolithography and two roll printing, two photolithography and one roll printing.

In addition to this, the present invention can be applied to other colors (including transparent ones) even when colors other than red, green, and blue constitute color filters. It can be formed by arranging photolithography and roll printing appropriately with existing colors and added colors. At this time, when forming the color filter of the pixel immediately adjacent to each pixel, it is preferable to arrange so that photolithography and roll printing do not continue. In particular, when the photolithography is continuous, it may be desirable to allow the black matrix to be alternately arranged as much as possible, since the step of the black matrix portion is increased and the roll printing is continuous.

The present invention is also applicable to a method of manufacturing a liquid crystal display device in which a color filter is formed on a first substrate. When forming the color filter, the color filter may be formed on the first substrate instead of the second substrate on which the black matrix is formed. In particular, when manufacturing a liquid crystal panel having a color filter on transistor (COT) structure, a color filter may be manufactured using photolithography and roll printing.

According to the present invention, when the color filter is formed in parallel with photolithography and roll printing, the amount of production can be controlled. When manufacturing a color filter using only photolithography, the photolithography process is very complicated, and thus it takes a relatively long time. Therefore, it is difficult to supply a color filter substrate in time because it cannot keep up with the speed of other processes. However, in the case of roll printing, since the method is very simple, the process time can be shortened, so that the process time for forming the overall color filter is shortened.

In addition, the present invention is also excellent in economic savings. For photolithography, existing process lines can be used as they are. If the process is carried out by roll printing only, the initial investment cost for roll printing is required, but when mixed with the existing process, the investment cost can be reduced to 1/3 of the existing level and the productivity can be increased.

In addition, one of the drawbacks of photolithography necessarily involves the wet process, which caused staining on the substrate. However, by reducing the number of photolithography and including a roll printing process consisting of a dry (dry) process there is an advantage that the probability of staining is reduced.

It will be apparent to those skilled in the art that various changes and modifications can be made within the scope of the spirit of the present invention. Therefore, the scope of the present invention should be defined by the scope of the claims rather than the details of the description.

As described above, color filters are formed by photolithography and roll printing to simplify the process and reduce defects, thereby obtaining economic and time gains, thereby providing a higher quality liquid crystal display device.

Claims (8)

(a) forming a black matrix on the substrate; (b) forming at least one color filter on the substrate on which the black matrix is formed by using photolithography; And (c) forming a color filter of at least one color using roll printing with ink for forming color filters on the substrate on which the black matrix is formed. The method of claim 1, The color filter includes a red, green and blue color filter, Step (b) and step (c) is to form a color filter substrate, characterized in that to form a color filter of different colors. The method of claim 1, Color filter substrate manufacturing method characterized in that any one of the steps (b) and (c). The method of claim 3, The color filter further includes a color filter of a different color (including transparent) except for color filters of red, green, and blue, Forming the added color filter by any one of the steps (b) or (c). The method of claim 1, Step (c) is, (i) filling the printing roll with color filter ink; (ii) preparing a cliché formed with grooves corresponding to the negative region of the color filter pattern; (iii) contacting the printing roll on the cliché and rotating to form a pattern on the printing roll; And (iv) printing the printed roll having the pattern on the substrate. The method of claim 1, Step (c) is, (i) preparing a cliché formed with grooves for filling the color ink; (ii) filling a color ink into the cliché; (iii) transferring the color ink filled in the grooves of the cliché onto the printing roll by contacting and rotating the printing roll on the cliché; And (iv) printing the color ink transferred onto the surface of the printing roll on the substrate. The method of claim 6, Step (ii) is a step of filling the cells with a color ink of different colors in the plurality of cells, The step (iii) is a step of transferring the color ink filled in the grooves to the printing roll after sequentially contacting the cliché filled with the color ink of different colors on the printing roll. (a) preparing a first substrate having a thin film transistor and a second substrate facing the first substrate; (b) forming a black matrix on the first substrate or the second substrate; (c) forming at least one color filter on the first substrate or the second substrate on which the black matrix is formed by using photolithography; And (d) forming at least one color filter on the first substrate or the second substrate on which the black matrix is formed by using roll printing with ink for color filter formation; (e) forming a liquid crystal layer between the first substrate and the second substrate.

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