Abstract:
A liquid crystal display (LCD) panel including a color filter on array (COA) substrate and a manufacturing method thereof are proposed. Metallic layers of the substrate of the LCD panel replace a conventional black matrix and are used for blocking light so the occurrence of color mixing and light leakage is prevented. Since the conventional black matrix is unnecessary in the present invention, the process steps of forming the LCD panel are simplified. Not only yield rate is raised, but also cost is reduced.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The present invention relates to a liquid crystal display (LCD) panel and a manufacturing method thereof, and more particularly, to an LCD panel of using metallic layers to replace a conventional black matrix and a manufacturing method thereof. 
         [0003]    2. Description of the Prior Art 
         [0004]    An advanced monitor with multiple functions is an important feature for use in current consumer electronic products. Liquid crystal displays (LCDs) which are colorful monitors with high resolution are widely used in various electronic products such as monitors for mobile phones, personal digital assistants (PDAs), digital cameras, laptop computers, and notebook computers. 
         [0005]    A conventional LCD panel comprises a color filter, a thin film transistor array substrate (TFT array substrate), and a liquid crystal layer placed between the color filter and the TFT array substrate. The conventional LCD panel has shortcomings as follows: the resolution of the LCD panel is worse; the aperture ratio of pixels is lower; misalignment occurs easily when the color filter and the TFT array substrate are assembled. 
         [0006]    With recent progress in display technology, technology that a color filter is directly incorporated with a color filter on array (COA) substrate and that a black matrix is directly fabricated on a black matrix on array (BOA) substrate is proposed. The aforesaid COA substrate or the BOA substrate and an opposite substrate which does not comprise the color filter or the black matrix together form an LCD panel. Liquid crystal molecules are sandwiched between the opposite substrate and the COA substrate or the BOA substrate. Since the color filter is directly formed on the TFT array substrate, misalignment will not occur. Moreover, such an LCD panel has advantages of high resolution and a high aperture ratio. 
         [0007]      FIG. 1  shows a simplified cross-section diagram of an LCD panel  100  in a conventional technology. The LCD panel  100  is an LCD panel comprising a BOA substrate; that is, a color filter  130  is directly formed on a glass substrate  110  of the LCD panel  100 . As shown in  FIG. 1 , the LCD panel  100  comprises the glass substrate  110 , a black matrix  120 , and the color filter  130 . 
         [0008]    It is notified that, the LCD panel  100  comprises metallic layers used for forming data lines and scan lines, an insulating layer, a protection layer, etc., between the color filter  130  and the glass substrate  110  though these elements are not shown in  FIG. 1 . The function and structure of the elements is understood by persons skilled in the relevant art, so no explanations in more detail are given below. 
         [0009]    Continuing referring to  FIG. 1 , the color filter  130  is used for filtering light. Light becomes visible light having a specific color after being color filtered by the color filter  130 . In this embodiment, light is color filtered by red, blue, and green color filters  131 ,  132 , and  133 , and red light, blue light, green light pass through, respectively. Light with diverse colors is obtained after combining light with the three primary colors. Accordingly, images are shown on the LCD panel  100 . 
         [0010]    In addition, the black matrix  120  is placed between every two color filters  130  and is used for blocking light generated by a backlight module to prevent light from travelling through a plurality of color filters  130  falsely, thereby preventing color mixing and light leakage. 
         [0011]    Referring to  FIG. 2 ,  FIG. 2  is a simple cross-section diagram of an LCD panel  200  in another conventional technology. The structure of the LCD panel  200  in  FIG. 2  is basically similar to that of the LCD panel  100  in  FIG. 1 . Elements having the same function and structure are designated by the same reference numerals though they are shown in  FIG. 1  and in  FIG. 2 , and explanations in more detail will not be given below. It is notified that, an overcoat  210  is additionally deposited on the color filter  120  as shown in  FIG. 2 . The overcoat  210  is used for reducing the difference of the height of the substrate to allow the substrate to become flatter. The difference of the height of the substrate causes poor orientation of the liquid crystal molecules, resulting in light leakage. 
         [0012]    Today&#39;s LCD panels are manufactured using several process steps. The cost of manufacturing LCD panels will be greatly reduced if the black matrix is not used. 
       SUMMARY OF THE INVENTION 
       [0013]    Therefore, an object of the present invention is provide an LCD panel of using metallic layers to replace a conventional black matrix and a manufacturing method thereof. The present invention can effectively reduce cost and cut process steps. 
         [0014]    According to the present invention, a method of a liquid crystal display (LCD) panel comprising a color filter on array (COA) substrate is provided. The method comprises the steps of: providing a glass substrate; forming a first metallic layer on the glass substrate and etching the first metallic layer for forming a scan line, a gate of a thin film transistor (TFT), and a bottom electrode of a storage capacitor; depositing an insulting layer on the glass substrate and on the first metallic layer; depositing an active layer and an n+ layer on the insulting layer; etching the active layer and the n+ layer for defining the TFT, and the active layer being used as a passage of the TFT; depositing a second metallic layer on the n+ layer and on the insulating layer, etching the second metallic layer for forming a data line, and defining a source and a drain of the TFT on the n+ layer; depositing a passivation layer on the second metallic layer and on the insulating layer; etching the passivation layer for forming a first via on the drain of the TFT and forming a second via on top of the bottom electrode of the storage capacitor; depositing a color filter on the passivation layer and etching the color filter for forming a plurality of color filters; and depositing a transparent conducting layer on the color filter, coupling the transparent conducting layer to the drain of the TFT through the first via, and forming a top electrode of the storage capacitor on the second via wherein the first and second metallic layers are used for blocking light. 
         [0015]    In one aspect of the present invention, the method further comprises a step of: depositing an overcoat on the transparent conducting layer. 
         [0016]    In another aspect of the present invention, the plurality of color filters comprise a red color filter, a green color filter, and a blue color filter. 
         [0017]    According to the present invention, a method of manufacturing an LCD panel having a COA substrate is provided. The method comprises the steps of: providing a glass substrate; forming a scan line, a TFT, a data line, and a bottom electrode of a storage capacitor; depositing a passivation layer and etching the passivation layer to form a first via on a drain of the TFT and forming a second via on top of the bottom electrode of the storage capacitor; depositing a color filter on the passivation layer and etching the color filter to form a plurality of color filters; and depositing a transparent conducting layer on the color filter, coupling the transparent conducting layer to the drain of the TFT through the first via, and forming a top electrode of the storage capacitor on the second via. A projection of the data line or the scan line placed between every two neighboring color filters on the glass substrate is overlapped with a projection of every two neighboring color filters on the glass substrate. 
         [0018]    In one aspect of the present invention, the method further comprises: depositing an overcoat on the transparent conducting layer. 
         [0019]    In another aspect of the present invention, the plurality of color filters comprise a red color filter, a green color filter, and a blue color filter. 
         [0020]    According to the present invention, an LCD panel comprises a glass substrate; a first metallic layer, placed on the glass substrate, for forming a scan line, a gate of a TFT, and a bottom electrode of a storage capacitor; an insulating layer, placed on the glass substrate and on the first metallic layer; an active layer, placed on the insulating layer, for being used as a passage of the TFT; an n+ layer, placed on the active layer; a second metallic layer, placed on the n+ layer and on the insulating layer, for being used as a data line and a source and a drain of the TFT; a passivation layer, placed on the second metallic layer and on the insulating layer; a color filter, placed on the passivation layer, comprising a plurality of color filters, wherein a projection of the data line or the scan line placed between every two neighboring color filters on the glass substrate is overlapped with a projection of every two neighboring color filters on the glass substrate; and a transparent conducting layer, placed on the color filter, coupled to the drain of the TFT, and used as a top electrode of the storage capacitor. The first and second metallic layers are used for blocking light. 
         [0021]    In one aspect of the present invention, the LCD panel further comprises an overcoat, placed on the transparent conducting layer. 
         [0022]    In another aspect of the present invention, the plurality of color filters comprise a red color filter, a green color filter, and a blue color filter. 
         [0023]    In contrast to the conventional technology, the black matrix is replaced by metallic layers which serve as data lines or scan lines in the present invention. Because the process step of using the black matrix is skipped, the process steps of forming the LCD panel are simplified. Not only yield rate is raised, but also cost is reduced. 
         [0024]    These and other features, aspects and advantages of the present disclosure will become understood with reference to the following description, appended claims and accompanying figures. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0025]      FIG. 1  shows a simplified cross-section diagram of an LCD panel in a conventional technology. 
           [0026]      FIG. 2  is a simple cross-section diagram of an LCD panel in another conventional technology. 
           [0027]      FIG. 3  shows a schematic diagram of an LCD panel according to an embodiment of the present invention. 
           [0028]      FIGS. 4A-4C  to  9 A- 9 C illustrate processes for forming the LCD panel as shown in  FIG. 3 . 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0029]    Spatially relative terms, such as “beneath”, “below”, “lower”, “above”, “upper” and the like, may be used herein for ease of description to describe one element or feature&#39;s relationship to another element(s) or feature(s) as illustrated in the figures. It will be understood that the spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. 
         [0030]    Referring to  FIG. 3 ,  FIG. 3  shows a schematic diagram of an LCD panel  300  according to an embodiment of the present invention. The LCD panel  300  comprises a glass substrate  310 , a plurality of scan lines SL, a plurality of data lines DL, a plurality of TFTs  220 , a plurality of common electrodes CL, and a plurality of pixel electrodes  360 . The plurality of scan lines SL, the plurality of data lines DL, and the plurality of TFTs  220  all are disposed on the glass substrate  310 . The plurality of scan lines SL and the plurality of data lines DL are alternatively arranged, which forms a matrix-arranged pixel area. Each of the plurality of TFTs  220  is electrically connected to a pixel electrode  360 , a scan line SL, and a data line DL. 
         [0031]    Referring to  FIG. 3  and  FIGS. 4A-4C ,  FIGS. 4A-4C  show cross-section views of the LCD panel  300  taken along lines A-A′, B-B′, and C-C′ of  FIG. 3 . As shown in  FIGS. 4A-4C , the LCD panel  300  comprises the glass substrate  310 , an insulating layer  320 , a TFT  220 , a passivation layer  340 , and a plurality of color filters  350 . The LCD panel  300  is an LCD panel comprising a COA substrate; that is, the plurality of color filters  350  and the TFT  220  all are formed on the same glass substrate  310 . The scan lines SL, a gate  221  of the TFT  220 , and the common electrode CL all are disposed on the glass substrate  310  and all are formed by the same first metallic layer. The insulating layer  320  is placed on the glass substrate  310  and on the first metallic layer. An active layer  541  is placed on the insulating layer  320  and is used as a channel  224  of the TFT  220 . An n+ layer  542  is placed on the active layer  541 . A second metallic layer is placed on the n+ layer  542  and on the insulating layer  320  and is used as the data line DL and a source  222  and a drain  223  of the TFT  220 . The passivation layer  340  is placed on the second metallic layer and on the insulating layer  320 . The plurality of color filters  350  are disposed on the passivation layer  340 . An overcoat  460  is placed on the plurality of color filters  350  and is used for making the top of the plurality of color filters  350  be flattened. In this way, light leakage occurring due to disclination of the liquid crystal molecules is avoided. A transparent conducting layer (i.e. a pixel electrode)  360  is placed on the overcoat  460  and is coupled to the drain  223  of the TFT  220 . The transparent conducting layer  360  also serves as a top electrode of a storage capacitor. 
         [0032]    The plurality of color filters  350  comprise a red color filter, a blue color filter, and a green color filter for filtering respective wavelengths of light, e.g. red light, blue light, and green light. Mixtures of red light, blue light, and green light may appear various colors. Because the plurality of data lines DL and the plurality of scan lines SL are arranged perpendicularly and alternatively, a pixel matrix is formed on the LCD panel  300 . The plurality of data lines DL and the plurality of scan lines SL are disposed between every two neighboring color filters  350 . The plurality of data lines DL and the plurality of scan lines SL can effectively block light. In addition, each of the plurality of color filters  350  forms a trapezoid-like inclined angle L when being formed, resulting in disclination of the liquid crystal molecules in areas of the inclined angles L, thereby leading to light leakage. The projection of one of the data lines DL and one of the scan lines SL placed between every two neighboring color filters  350  on the glass substrate  310  is overlapped with that of every two neighboring color filters  350  on the glass substrate  310 . Since the plurality of data lines DL and the plurality of scan lines SL all are made of metal, they are good at blocking light. Each data line DL or each scan line SL overlapping the color filters  350  can effectively prevent not only light leakage between every two neighboring color filters  350  but also light leakage resulting from disclination of liquid crystal molecules. Moreover, the overlapping area can successfully suppress color mixing among the plurality of color filters  350 . 
         [0033]    It is notified that, the plurality of data lines DL and the plurality of scan lines SL replace the black matrix used for preventing light leakage and color mixing from occurring in the present invention. In other words, light leakage and color mixing do not occur even though the black matrix is not used. As can be seen, the process steps of forming the LCD panel  300  are simplified in the present invention. Not only yield rate is raised, but also cost is reduced. 
         [0034]    Referring to  FIGS. 4A-4C  to  9 A- 9 C,  FIGS. 4A-4C  to  9 A- 9 C illustrate processes for forming the LCD panel  300  as shown in  FIG. 3 . 
         [0035]    Referring to  FIGS. 5A-5C , firstly, a first metallic layer is formed on a glass substrate  310 . Then, the first metallic layer is etched for forming a plurality of scan lines SL, a gate  221  of a TFT  220 , and a plurality of common electrodes CL used as a bottom electrode of a storage capacitor. 
         [0036]    Referring to  FIGS. 6A-6C , next, an insulating layer  320  is deposited on the glass substrate  310  and on the first metallic layer. Then, an active layer  541  and an n+layer  542  are deposited on the insulating layer  320 . Then, the active layer  541  and the n+layer  542  are etched to define a passage  224  of the TFT  220 . 
         [0037]    Referring to  FIGS. 7A-7C , next, a second metallic layer (M 2 )  532  is deposited on the n+ layer  542  and on the insulating layer  320 . Then, the second metallic layer (M 2 )  532  is etched for forming a plurality of data lines DL. A source  222  and a drain  223  of the TFT  220  are defined on the n+ layer  542 . 
         [0038]    Referring to  FIGS. 8A-8C , next, a passivation layer  340  is deposited on the n+ layer  542  and on the insulating layer  320 . Then, the passivation layer  340  is etched for forming a first via  231  on the drain  223  and a second via  232  on the plurality of common electrodes CL. 
         [0039]    Referring to  FIGS. 9A-9C , next, a color filter is deposited on the passivation layer  340 . Then, the color filter is etched for forming a plurality of color filters  350 . 
         [0040]    Referring to  FIGS. 4A-4C , next, an overcoat  460  is deposited on the plurality of color filters  350 . Then, a transparent conducting layer  360  is deposited on the overcoat  460 . The transparent conducting layer  360  is coupled to the drain  223  of the TFT  220  through the first via  231 . The transparent conducting layer  360  forms a top electrode of the storage capacitor on the second via  232 . The projection of the plurality of data lines DL and the plurality of scan lines SL disposed between every two neighboring color filters  350  on the glass substrate  310  is overlapped with that of every two neighboring color filters  350  on the glass substrate  310 . The plurality of data lines DL and the plurality of scan lines SL all are made of metal for blocking light. 
         [0041]    So far, the LCD panel  300  is almost done, and persons skilled in the art should understand the following process steps of completing the LCD panel  300 . No explanations in more detail will be given below. 
         [0042]    While the present invention has been described in connection with what is considered the most practical and preferred embodiments, it is understood that this invention is not limited to the disclosed embodiments but is intended to cover various arrangements made without departing from the scope of the broadest interpretation of the appended claims.