Patent Publication Number: US-2006001801-A1

Title: Method for fabricating a color filter substrate

Description:
This application claims the benefit of the Korean Patent Application No. P2004-50216 filed on Jun. 30, 2004, which is hereby incorporated by reference.  
     BACKGROUND OF THE INVENTION  
      1. Field of the Invention  
      The present invention relates to a fabricating method of a liquid crystal display panel, and more particularly, to a method for fabricating a color filter substrate of a liquid crystal display panel.  
      2. Description of the Related Art  
      A liquid crystal display device controls the light transmissivity of liquid crystal, which has dielectric anisotropy, by use of electric field, thereby displaying a picture. For this, the liquid crystal display device includes a liquid crystal display panel, which displays a picture through a liquid crystal cell matrix, and a drive circuit to drive the liquid crystal display panel.  
      As shown in  FIG. 1 , the related art liquid crystal display panel includes a color filter substrate  10  and a thin film transistor substrate  20  which are bonded together with liquid crystal  24  therebetween.  
      The color filter substrate  10  includes a black matrix  4 , a color filter  6  and a common electrode  8  which are sequentially formed on an upper glass substrate  2 . The black matrix  4  is formed on the upper glass substrate  2  in a matrix shape. The black matrix  4  divides an area of the upper glass substrate  2  into a plurality of cell areas where the color filter  6  is to be formed, and it prevents the light interference between adjacent cells and the reflection of an external light. The color filter  6  is divided into red R, green G and blue B filters at the cell area, which is divided by the black matrix, and transmits each of red, green and blue lights. The common electrode  8  is of a transparent conductive layer which is spread on the entire surface of the color filter  6 . The common electrode  8  supplies a common voltage Vcom which becomes the reference voltage when driving the liquid crystal  24 . To level the color filter  6 , an overcoat layer (not shown) is formed between the color filter  6  and the common electrode  8 .  
      The thin film transistor substrate  20  includes a pixel electrode  22  and a thin film transistor  18 , which are formed at each cell area that is defined by the crossing of a gate line  14  and a data line  16 , on a lower glass substrate  12 . The thin film transistor  18  supplies a data signal from the data line  16  to the pixel electrode  22  in response to a gate signal from the gate line  12 . The pixel electrode  22  formed of a transparent conductive layer supplies the data signal from the thin film transistor  18  to drive the liquid crystal  24 .  
      The liquid crystal molecules  24  having dielectric anisotropy rotate in accordance with an electric field, formed by the data signal of the pixel electrode  22  and the common voltage Vcom of the common electrode  8 , to control the light transmissivity, thereby realizing the gray level.  
      The liquid crystal display panel further includes a spacer (not shown) to maintain a cell gap between the color filter substrate  10  and the thin film transistor substrate  20 . The spacer can be a ball spacer or a column spacer (not shown). The column spacer is mainly used in a drop-filling liquid crystal forming method and for a large-sized liquid crystal panel. It is typically formed over the overcoat layer that covers the color filter.  FIGS. 2A  to  2 E illustrate a related art method for fabricating a color filter substrate with column spacer.  
      As shown in  FIG. 2A , a black matrix  40  is formed on a substrate  30 . The black matrix  40  is formed as a matrix shape by depositing a black matrix material of metal or resin group on the substrate  30  and then patterning it by a mask process.  
      The black matrix  40  formed on the substrate  30  is then reviewed under a microscope. If a pinhole  40 A is found, a black ink is injected by an inkjet method to repair the pinhole  40 A of the black matrix  40  as in  FIG. 2B .  
      As shown in  FIG. 2C , the R, G, and B color filters are sequentially formed at the corresponding pixel areas on the substrate  30  where the black matrix  40  is formed. The R, G and B color filters are sequentially formed at the corresponding cell areas by repeating a photolithography process in which a corresponding color resist material is formed over the substrate and then exposed and developed.  
      The R, G, and B color filters are reviewed under a microscope. If a pinhole  42  is found, the corresponding color ink is injected by an ink jet method to repair the pinhole  42  of the color filter as shown in  FIG. 2D .  
      As shown in  FIG. 2E , an overcoat layer  44  is formed on the R, G, and B color filters for leveling. The overcoat layer  44  is formed by coating a transparent organic insulating material over the R, Q and B color filters and hardening it. Further, the overcoat layer  44  is patterned by an exposure and development process to be formed only at a picture display area where the R, G, B color filters are formed.  
      As shown in  FIG. 2F , column spacers  46  are formed on the overcoat layer  44 . The column spacers  46  are formed by coating a spacer resist over the overcoat layer  44  and patterning it by the exposure and development process.  
      In the related art color filter fabricating method, the pinhole of the black matrix is repaired by the review/repair process after the black matrix is formed, and then the pinhole of the color filter is repaired by the review/repair process after the R, G, and B color filters are formed. Accordingly, there is a disadvantage in that the production efficiency of the color filter substrate decreases because the review/repair process for removing the pinhole are performed twice.  
     SUMMARY OF THE INVENTION  
      Accordingly, the present invention is directed to a method of fabricating a color filter substrate for a display device that substantially obviates one or more of problems due to limitations and disadvantages of the related art.  
      An object of the present invention is to provide a pinhole repair method of a color filter substrate that is adaptive for effectively repairing a pinhole which is formed at a black matrix or a color filter.  
      Additional features and advantages of the invention will be set forth in the description which follows, and in part will be apparent from the description, or may be learned by practice of the invention. The objectives and other advantages of the invention will be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings.  
      To achieve these and other objects of the invention, method for fabricating a color filter substrate for use in a display device includes: forming a black matrix on a substrate; forming a color filter layer over the black matrix and the substrate; forming an overcoat layer over the color filter layer; inspecting the black matrix and the color filter layer for pinholes; and if a pinhole is detected in the black matrix or the color filter layer, repairing the detected pinhole by injecting a corresponding ink into the pinhole.  
      In another aspect of the present invention, a method for fabricating a color filter substrate for use in a display device includes: forming a black matrix on a substrate; forming a color filter layer over the black matrix and the substrate; forming an overcoat layer over the color filter layer; inspecting the color filter layer for pinholes; and if a pinhole is detected in the color filter layer, repairing the detected pinhole by injecting a corresponding ink into the pinhole after forming the overcoat layer.  
      In yet another aspect of the present invention, method for fabricating a color filter substrate for use in a display device includes: forming a black matrix on a substrate; forming a color filter layer over the black matrix and the substrate; forming an overcoat layer over the color filter layer; inspecting the black matrix for pinholes; and if a pinhole is detected in the black matrix, repairing the detected pinhole by injecting a corresponding ink into the pinhole after forming the overcoat layer.  
      It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are intended to provide further explanation of the invention as claimed. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
      The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the principles of the invention. In the drawings:  
       FIG. 1  is a perspective view illustrating a related art liquid crystal display panel structure;  
       FIGS. 2A  to  2 E are sectional diagrams illustrating a related art method for fabricating a color filter substrate step by step; and  
       FIGS. 3A  to  3 C are sectional diagrams illustrating a fabricating method of a color filter substrate step by step according to a first exemplary embodiment of the present invention.  
       FIGS. 4A and 4B  are sectional diagrams illustrating a fabricating method of a color filter substrate step by step according to a second exemplary embodiment of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
      Reference will now be made in detail to the preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings.  
      Hereinafter, the preferred embodiments of the present invention will be described in detail with reference to  FIGS. 3A  to  3 C,  4 A, and  4 B. In the fabricating method according to the first exemplary embodiment of the present invention, as shown in  FIG. 3A , a black matrix  60  and R, G, and B color filters are sequentially formed on a substrate  50 . An overcoat layer  64  is then formed on the R, G and B color filters.  
      The black matrix  60  is formed in a matrix shape by patterning a black matrix material of metal or resin group by a mask process after depositing the black matrix material on the entire surface of the substrate  50 .  
      The R, G, and B color filters are sequentially formed at corresponding cell areas by repeating a photolithography process in which a corresponding color resist is formed over the substrate  50  and exposed and developed.  
      The overcoat layer  64  is then formed by coating a transparent organic insulating material over the R, G, and B color filters and then hardening it. Further, the overcoat layer  64  is patterned by the exposure and development process to cover only a picture display area where the R, G, and B color filters are formed.  
      The color filter substrate where the overcoat layer  64  is formed is then reviewed under a microscope. If a pinhole  62  exists in the R, G, and B color filters, a laser  66  is irradiated to form an ink injection hole  64 A through the overcoat layer  64  in the area substantially corresponding to the pinhole  62  of the color filter. Then, a corresponding ink is injected into the pinhole  62  of the color filter through the ink injection hole  64 A of the overcoat layer  64 , thereby repairing the pinhole  46 A of the color filter as shown in  FIG. 3B .  
      As shown in  FIG. 3C , a column spacer  68  is formed on the overcoat layer  64 . The column spacer  68  is formed by coating a spacer resist over the overcoat layer  64  and then patterning it by the exposure and development process.  
       FIGS. 4A and 4B  illustrate a second exemplary embodiment of the present invention. After the overcoat layer  64  is formed, the black matrix  60  is reviewed under a microscope. As shown in  FIG. 4A , if a pinhole  72  exists in the black matrix  60 , a laser  76  is irradiated to form an ink injection hole  74  through the overcoat layer  64  and at least one of the R, Q and B color filters in the area substantially corresponding to the pinhole  72  in the black matrix  60 . Then, as shown in  FIG. 4B , a black ink is injected into the pinhole  72  in the black matrix  60  through the ink injection hole  74 , thereby repairing the pinhole  72 . A column spacer is formed on the overcoat layer  64  as described above.  
      The R, Q and B color filters and black matrix  60  can be examined under a microscope for pinholes in a single review step after the overcoat layer  64  is formed. Then, the repair of the pinhole  62  in the color filters, as shown in  FIGS. 3A and 3B , and the repair of the pinhole  72  in the black matrix  60 , as shown in  FIGS. 4A and 4B , can be performed in the same repair step.  
      In another exemplary embodiment of the present invention, the foregoing pinhole repair method of the R, G, and B color filters and the black matrix  60  can be applied after the column spacer  68  is formed. In other words, the pinhole repair method for the color filter substrate according to the embodiments of the present invention repairs the pinhole with a single review/repair process after the overcoat layer  64  or the column spacer  68  is formed. Accordingly, the number of review/repair processes can be reduced to one.  
      As described above, the method of fabricating a color filter substrate according to the present invention repairs pinholes, which are formed in the R, G, and B color filters and/or the black matrix, with a single review/repair process after the overcoat layer or the column spacer is formed. Accordingly, the number of pinhole review/repair process for the color filter substrate can be reduced to one, thereby improving the production efficiency.  
      It will be apparent to those skilled in the art that various modifications and variations can be made in the method for fabricating a color filter substrate of a liquid crystal panel according to the present invention without departing from the spirit or scope of the invention. Thus, it is intended that the present invention cover the modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents.