Patent Document

CROSS REFERENCE TO PRIOR APPLICATIONS 
     This application is a Divisional of U.S. patent application Ser. No. 13/846,707, filed Mar. 18, 2013, which is a Divisional of U.S. patent application Ser. No. 13/193,508 filed Jul. 28, 2011, which is a Divisional of U.S. patent application Ser. No. 11/244,099 filed Oct. 6, 2005, which is a Continuation application of U.S. patent application Ser. No. 09/615,794 filed Jul. 13, 2000, which claims priority to and the benefit of Korean Patent Application Nos. 10-1999-0028287 filed on Jul. 13, 1999; 10-1999-0048841 filed on Nov. 5, 1999; and 10-1999-0067761 filed Dec. 31, 1999, which are incorporated herein by reference in their entireties. 
    
    
     BACKGROUND OF THE INVENTION 
     (a) Field of the Invention 
     The present invention relates to a liquid crystal display and, more particularly, to a liquid crystal display which bears uniform brightness characteristic over the entire screen area without leakage of light. 
     (b) Description of the Related Art 
     Generally, a liquid crystal display has an upper substrate with a common electrode and color filters (usually called the “color filter substrate”), a lower substrate with thin film transistors and pixel electrodes (usually called the “TFT array substrate”), and a liquid crystal layer sandwiched between the color filter substrate and the TFT array substrate. Different electrical potentials are applied to the pixel electrodes and the common electrode while forming electric fields to change the liquid crystal molecule orientation. In this way, the light transmission is controlled to display picture images. 
     In such a liquid crystal display, with only a TFT attached to it, the charge applied to switch the liquid crystal leaks away in a brief time after a signal arrives. Therefore, it is necessary to connect an additional capacitor to the liquid crystal so that the liquid crystal is able to retain the charge associated with the first signal until a second signal is received. 
     For example, a capacitance may be conferred on a liquid crystal by using an adjacent gate electrode line. 
     Each pixel electrode overlaps over the previous gate line with an insulating layer interposed to form a storage capacitance Cst. The pixel electrode faces the common electrode with a liquid crystal layer interposed to form a liquid crystal capacitance Clc. Furthermore, a parasitic capacitance Cgd is formed between a gate electrode and a drain electrode. 
     The voltage applied between each pixel electrode and the common electrode changes at 60 Hz (60 frames per second). Within one frame, pulses of Von are applied to sequentially turn on TFTs from the first gate line to the last gate line. In case the Von pulse is applied to a particular gate line, off-voltages Voff are applied to the other gate lines. When the voltage applied to the common electrode Vcom is set to 5 V, the on-voltage Von becomes to be about 20 V, and the off-voltage Voff to be about −7 V. When the on-voltage Von is applied to a particular gate line, the TFTs positioned at that line are in an on-state, and the picture signal voltages applied to the data lines are transmitted to the pixel electrodes. In contrast, when the off-voltage Voff is applied to the TFTs at the particular gate line while applying Von to the previous gate line, the electric potential Vg of the previous gate line is elevated by 27 V from −7 V to 20 V. At this time, the electric potential of the pixel electrode Vp is also increased. The amount of increased potential of the pixel electrode ΔVp can be expressed by the following equation: ΔVp=[Cst/(Cst+Clc+Cgd+other parasitic capacitance)]×ΔVg(=27 V). 
     At this time, the liquid crystal capacitance Clc as a function of voltage difference between Vcom and Vp as well as the parasitic capacitance Cgd are varied together. Thereafter, when the previous gate line is shifted from Von to Voff, the electric potential of the pixel electrode Vp returns to the initial state, but not the liquid crystal capacitance Clc and the parasitic capacitance Cgd due to voltage dependence thereof. As such a variation in electrical potentials of the pixel electrodes at the second to last gate lines are made in the same pattern, the pixel electrode portions at the second to last gate lines bears uniform brightness at the same gray scale. However, since the pixel electrodes at the first gate line have no previous gate line, the electrical potentials of those electrodes change in different manner and the brightness becomes different in the same gray scale. As the brightness at the first gate line portion is usually brighter compared to other gate line portions, the picture images displayed at that portion disturbs the human eye. 
     In order to solve such a problem, the technique of adding a storage capacitor line G 0  and connecting it to the second gate line G 2  or the last gate line Gm has been proposed. However, when the G 0  line is connected to the G 2  line, the integrated circuit (IC) for driving the G 2  line should be also employed for driving the G 0  line, resulting in shortage in driving current. Accordingly, the second gate line portion becomes much brighter than other gate line portions at a normally white mode. This phenomenon becomes serious as the electric load applied to each gate line becomes greater with the trend of high definition and increased screen size. In contrast, when the G 0  line is connected to the Gm line, complicated wiring via printed circuit boards (PCBs) should be made to interconnect the G 0  line and the Gm line, and the first and the last gate line portions differs in brightness from the other gate line portions. 
     In the meantime, the TFT array substrate usually has a size larger than the color filter substrate. In this connection, when assembled, the periphery of the TFT array substrate without the corresponding black matrix portion is exposed to the outside so that light leaks at the exposed portion. 
     SUMMARY OF THE INVENTION 
     It is an object of the present invention to provide a liquid crystal display which bears good picture quality with uniform brightness characteristic over the entire screen area. 
     It is another object of the present invention to provide a liquid crystal display which effectively prevents light leakage without generating short circuits. 
     These and other objects may be achieved by employing in a liquid crystal display light interception patterns. Alternatively, a liquid crystal display may have a black matrix with openings of different sizes depending on the pixel positions. A manufacturing method is also disclosed. 
     According to one aspect of the present invention, the liquid crystal display includes first and second insulating substrates facing to each other, and a liquid crystal injected into the gap between the first and second substrates. A plurality of gate lines is formed at the first substrate to transmit scanning signals, and data lines cross over the gate lines to transmit picture signals. Pixels are demarcated by the gate lines and the data lines. The gate lines demarcate the pixels into rows, and the data lines demarcate the pixels into columns. A black matrix defines each pixel, and a pixel electrode is formed at each pixel. A storage capacitor line is formed at the first substrate parallel to the gate line, and overlapped with the pixel electrodes at the first pixel row. Storage capacitors are formed between the pixel electrodes and the previous gate lines as well as between the pixel electrodes and the storage capacitor line. A gate-off voltage or a common electrode voltage is applied to the storage capacitor line. Each pixel at the first pixel row with the storage capacitor formed between the corresponding pixel electrode and the storage capacitor line has an opening ratio different from that of the pixels at the other pixel rows. The opening ratio of the first pixel row is established to be 60-80% of the opening ratio of the other pixel rows. 
     The opening ratio is made different by forming a light interception pattern at each pixel of the first pixel row, or by changing opening volumes of the black matrix. The light interception pattern may be formed at the same layer as the data line or the gate line with the same material. 
     A gate-off line is formed at the first substrate to transmit a gate-off voltage, and the gate-off line and the storage capacitor line are formed at the same layer as the gate line. The gate-off line and the storage capacitor line are electrically connected to each other via a connection member, and the connection member is formed at the same layer as the data line or the pixel electrode. 
     In the above structure, uniform brightness over the entire screen area can be ensured. 
     According to another aspect of the present invention, the liquid crystal display includes a first insulating substrate, and a gate line assembly formed at the first insulating substrate. The gate line assembly has a plurality of gate lines, gate electrodes branched from the gate lines, and gate pads connected to the gate lines to transmit scanning signals thereto. First light interception patterns are isolated from the gate line assembly. A gate insulating layer covers the gate line assembly and the first light interception patterns. A semiconductor layer is formed on the gate insulating layer, and an ohmic contact layer is formed on the semiconductor layer. A data line assembly is formed on the semiconductor layer and the gate insulating layer. The data line assembly has a plurality of data lines crossing over the gate lines while forming pixel areas, source electrodes branched from the data lines, drain electrodes positioned opposite to the source electrodes while centering around the gate electrodes, and data pads connected to the data lines to transmit picture signals thereto. The pixel areas collectively forms a display area. Second light interception is patterns are isolated from the data line assembly. A protective layer covers the data line assembly and the second light interception patterns while forming first to third contact holes exposing the gate pad, the data pad and the drain electrode, respectively. Pixel electrodes are connected to the drain electrodes via the third contact hole. A subsidiary gate pad covers each gate pad via the first contact hole, and a subsidiary data pads covers each data pad via the second contact hole. 
     A second insulating substrate faces the first substrate, and color filters are formed at the second substrate while corresponding to the pixel areas. A black matrix is formed at the second substrate while surrounding the color filters, and a common electrode covers the color filters and the black matrix. A sealer seals the first and second substrates together. 
     The first and second light interception patterns are positioned outside of the display area such that they are overlapped with the black matrix, but not with the gate and data lines, and the sealer. 
     In the above structure, possible light leakage can be prevented with the light interception patterns without generating short circuits. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       A more complete appreciation of the invention, and many of the advantages thereof, will be readily apparent as the same becomes better understood by reference to the following detailed description when considered in conjunction with the accompanying drawings in which like reference symbols indicate the same or the similar components, wherein: 
         FIG. 1  is a plan view of a liquid crystal display according to a first preferred embodiment of the present invention; 
         FIG. 2  is a cross sectional view of the liquid crystal display taken along the II-II′ line of  FIG. 1 ; 
         FIG. 3  is another plan view of the liquid crystal display shown in  FIG. 1  illustrating the wiring structure; 
         FIG. 4  is a circuit diagram of the liquid crystal display shown in  FIG. 1 ; 
         FIG. 5  is a plan view of a liquid crystal display with a black matrix according to a second preferred embodiment of the present invention; 
         FIG. 6  is a cross sectional view of the liquid crystal display taken along the VI-VI′ line of  FIG. 5 ; 
         FIG. 7  is a plan view of the black matrix shown in  FIG. 5 ; 
         FIG. 8  is a plan view of a liquid crystal display according to a third preferred embodiment of the present invention; 
         FIG. 9  is a circuit diagram of the liquid crystal display shown in  FIG. 8 ; 
         FIG. 10  is a plan view of a liquid crystal display according to a fourth preferred embodiment of the present invention; 
         FIG. 11  is another plan view of the liquid crystal display shown in  FIG. 10  illustrating the wiring structure; 
         FIG. 12  is a cross sectional view of the liquid crystal display taken along the XII-XII′ line of  FIG. 11 ; 
         FIG. 13  is a cross sectional view of the liquid crystal display taken along the XIII-XIII′ line of  FIG. 11 ; 
         FIGS. 14A to 17B  are views sequentially illustrating the steps of processing the liquid crystal display shown in  FIG. 10 ; 
         FIG. 18  is a plan view of a liquid crystal display according to a fifth preferred embodiment of the present invention; 
         FIG. 19  is a cross sectional view of the liquid crystal display taken along the XIX-XIX′ line of  FIG. 18 ; and 
         FIG. 20  is a cross sectional view of the liquid crystal display taken along the XX-XX′ line of  FIG. 18 . 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Preferred embodiments of this invention will be explained with reference to the accompanying drawings. 
       FIG. 1  is a plan view of a liquid crystal display according to a first preferred embodiment of the present invention where one pixel area of the first pixel row is illustrated, and  FIG. 2  is a cross sectional view of the liquid crystal display taken along the II-II′ line of  FIG. 2 . The liquid crystal display according to the present invention has a basic structure where a liquid crystal layer is sandwiched between upper and lower substrates with a plurality of pixel areas at different pixel rows, and the following description will be made with respect to one pixel area at the first pixel row. 
     As shown in the drawings, the lower substrate  10  is overlaid with a first gate line  22  proceeding in the horizontal direction, a gate electrode  26  branched perpendicularly from the first gate line  22  and a storage capacitor line G 0  proceeding parallel to the first gate line  22 . A gate insulating layer  30  is formed on the gate line  22 , the gate electrode  26 , and the storage capacitor line G 0 . A semiconductor layer  40  is formed on the gate insulating layer  30  over the gate electrode  26 , and a data line  62  is formed on the gate insulating layer  30  while crossing perpendicularly over the first gate line  22  and the storage capacitor line G 0 . A source electrode  65  is branched perpendicularly from the data line  62 . A drain electrode  66  is positioned at the same plane as the source electrode  65  opposite thereto while centering around the gate electrode  26 . The source and drain electrodes  65  and  66  are placed over the semiconductor layer  40  by interposing ohmic contact layers  55  and  56 . 
     Of course, the storage capacitor line G 0  may be referred to as the first gate line if it functions as an electrode part of a storage capacitor for the first pixel row. 
     A light interception pattern  67  is centrally formed at the pixel area with the same plane as the data line  62 , the source electrode  65  and the drain electrode  66 . A protective layer  70  is formed on the data line  62 , the source electrode  65  and the drain electrode  66  with a contact hole  81  exposing the drain electrode  66 . A pixel electrode  80  is formed on the protective layer  70 , and connected to the drain electrode  66  via the contact hole  81 . The pixel electrode  80  is formed with a transparent material such as indium tin oxide (ITO), and partially overlapped with the storage capacitor line G 0 . Each pixel area is demarcated by the two data lines  62  crossing over the neighboring two gate lines, and the pixel electrode  80  covers the entire pixel area. 
     A black matrix  91  and color filters (not shown) are formed on the upper substrate  90  such that they face the lower substrate  10 . The black matrix  91  is formed of opaque material that can prevent light leakage. It also defines each pixel area. A common electrode  92  is formed on the black matrix  91  and the color filters. It covers the entire upper substrate  90 . Alternatively, the black matrix  91  and the color filters may be formed at the lower substrate  10 . 
     In the above pixel structure, the pixel electrodes  80  at the first pixel row overlap the storage capacitor line G 0  to form a desired storage capacitance. On the other hand, the pixel electrodes  80  of the second to the last pixel rows overlap the previous corresponding gate lines  22  respectively. 
     The first pixel row has an opening ratio lower than that of the other pixel rows due to the presence of the light interception patterns  67 . 
     The light interception pattern  67  may be formed either at the same layer as the data line  62 , the source electrode  65  and the drain electrode  66 , or at the same layer as the gate line  22  and the gate electrode  26 . 
     As shown in  FIG. 3 , when the lower substrate  10  is combined with the upper substrate  90 , the periphery of the lower substrate  10  is exposed to the outside because it is larger than the upper substrate  90 . Gate signal transmission films  28  are arranged at the exposed portion of the lower substrate  10  in the longitudinal direction of the data lines  62 . Each gate signal transmission film  28  is provided with a gate driving integrated circuit  27 . The gate driving integrated circuit  27  is electrically connected to the gate lines  22 , and outputs gate driving signals. Data signal transmission films  68  are arranged at the exposed portion of the lower substrate  10  in the longitudinal direction of the gate lines  22 . Each data signal transmission film  68  is provided with a data driving integrated circuit  67 . The data driving integrated circuit  67  is electrically connected to the data lines  62 , and outputs data driving signals. Furthermore, a printed circuit board  12  for driving the liquid crystal display is connected to the data signal transmissions  68 . 
     Meanwhile, a common electrode wire  71  for applying the common electrode voltage Vcom to the common electrode  92 , a gate-on wire  72  for applying the on-voltage Von to the TFTs, and a gate-off wire for applying the off-voltage Voff to the TFTs are formed on the edge portion of the lower substrate  10  between the gate signal transmission film  28  and the data signal transmission film  68 . Additional wires for transmitting carry-in or gate-clock signals may be further provided. 
     As shown in  FIGS. 3 and 4 , the storage capacitor line G 0  at the first pixel row is connected to the gate-off wire  73  via a connection member such that the gate-off voltage Voff is transmitted thereto. It is preferable that the common electrode wire  71 , the gate-on wire  72  and the gate-off wire  73  are formed at the same layer as the storage capacitor line G 0  and the gate lines  22  with the same material. The connection member  77  is formed at the same layer as the data lines  62  or the pixel electrodes  80  with the same material. The protective layer  70  or the gate insulating layer  30  has a contact hole that receives the connection member  77 . 
     Because the substrate  10  has the wires  71  to  73  that transmit appropriate signals to the gate driving integrated circuit  27 , a connector that interconnects a gate printed circuit board and a data printed circuit board may be eliminated. Furthermore, as in this preferred embodiment, only the data printed circuit board may be used without the gate printed circuit board. 
     The gate driving integrated circuit  27  and the data driving integrated circuit  67  may be directly mounted onto the lower substrate  10 . 
     As described above, the opening ratio of the first pixel row is lower to compensate a possible increase in brightness at the first pixel row when applying the off-voltage Voff to the storage capacitor line G 0 . Furthermore, even though slight darkness is present at the first pixel row portion due to the presence of the light interception patterns  67 , it is not unpleasant to the eye, producing good picture quality. 
     It turns out that the optimal opening ratio of the first pixel row lies in the range of 60-80% of the other pixel rows. Of course, such a value may be slightly different depending upon the factors such as light transmission, Clc, or Cst. 
     In this way, the resulting liquid crystal display can bear good picture quality by compensating brightness differences with a simplified wiring structure. 
     Alternatively, in order to reduce the opening ratio of the first pixel row, the opening portions of the black matrix  91  at the first pixel row may be reduced to be smaller than those of the black matrix  91  at the other pixel rows. 
       FIG. 5  is a plan view of a liquid crystal display according to a second preferred embodiment of the present invention where one pixel area at the first pixel row is illustrated, and  FIG. 6  is a cross sectional view of the liquid crystal display taken along the VI-VI′ line of  FIG. 5 . In this preferred embodiment, other components and structures of the liquid crystal display are the same as those related to the first preferred embodiment except that the first pixel row&#39;s opening portions of the black matrix  91  are different in lengths from the other pixel rows and that the light interception patterns  67  is eliminated. 
     As shown in  FIG. 7 , the opening portions  93  of the black matrix  91  at the first pixel row are designed to have a smaller length than the opening portions  94  at the other pixel rows to reduce the opening ratio of the first pixel row. That is, the opening portions  94  of the black matrix  91  at the second to last pixel rows have a width X and a length Y while being spaced apart from each other with a distance S on the row by row basis. However, the opening portions  93  of the black matrix  91  at the first pixel row have a length Y-a to be 60 to 80% of the length Y of the other opening portions  94 . 
     The structure where only the length of the opening portions  93  of the black matrix  91  at the first pixel row becomes decreased with a uniform width can produce better picture images. Of course, it is possible that the width and length of the opening portions  93  of the black matrix  91  at the first pixel row are all decreased to reduce the opening ratio at those portions. 
       FIGS. 8 and 9  illustrate a liquid crystal display according to a third preferred embodiment of the present invention. In this preferred embodiment, other components and structures of the liquid crystal display are the same as those related to the second preferred embodiment except that the common electrode voltage Vcom is applied to the storage capacitor electrode G 0  at the first pixel row, and the opening width and length of the black matrix  91  at the first pixel row are all designed to be shorter than those of the black matrix  91  at the other pixel rows. 
       FIG. 10  is a plan view of a liquid crystal display according to a fourth preferred embodiment of the present invention where a TFT array substrate  100  and a color filter substrate  110  are assembled via a sealer  3 . Since the TFT array substrate  100  is larger than the color filter substrate  110 , it is partially exposed to the outside. 
     As shown in  FIG. 10 , a plurality of gate lines  200  are formed at the TFT array substrate  100  in the horizontal direction, and gate pads  230  are connected to the end portions of the gate lines  200 . A plurality of data lines  610  are formed at the TFT array substrate  100  in the vertical direction, and data pads  640  are connected to the end portions of the data lines  610 . 
     A plurality of pixel areas P are existent at the TFT array substrate  100 . Each pixel area P is defined by the two data lines  610  crossing over the neighboring gate lines  200 , and a display area A can be indicated by the sum of the pixel areas P. A sealer  3  externally surrounds the display area A. 
     Color filters CF are formed at the color filter substrate  110  such that each color filter CF faces the corresponding pixel area of the TFT array substrate  100 . A black matrix BM surrounds the color filters CF such that it can prevent light leakage at the region between the neighboring pixel areas. As indicated in  FIG. 10  with the solid line  2 , the peripheral portion of the black matrix BM is placed inside the peripheral portion of the color filter substrate  110  while being positioned outside the sealer  3 . 
     In the above structure, lights tend to leak at the region B between the gate and data pads  230  and  640  and the black matrix BM. In order to prevent such a light leakage, light interception patterns  250  and  650  are formed at that region B such that they do not overlap the gate and data lines  200  and  610 , and the gate and data pads  250  and  650 . Furthermore, the light interception patterns  230  and  640  should not be overlapped with the sealer  3 , but may be overlapped with the black matrix BM. 
     Alternatively, the color filters CF and the black matrix BM may be formed at the TFT array substrate  100 . 
       FIG. 11  is an amplified view of the C portion of the liquid crystal display shown in of  FIG. 10 .  FIG. 12  is a cross sectional view of the liquid crystal display taken along the XII-XII′ line of  FIG. 11 .  FIG. 13  is a cross sectional view of the liquid crystal display taken along the XIII-XIIII′ line of  FIG. 11 . 
     As shown in the drawings, the TFT array substrate  100  is overlaid with a gate line assembly, and first light interception patterns  250 . The gate line assembly includes a plurality of gate lines  200 , gate electrodes  210  branched from the gate lines  200 , and gate pads  230  connected to the end portions of the gate lines  200  to receive scanning signals from the outside and transmit them to the gate lines  200 . The gate line assembly and the first light interception patterns  250  are placed on the same plane, and formed together with a conductive metallic material such as aluminum (Al), aluminum alloy, molybdenum (Mo), molybdenum-tungsten alloy (MoW), chrome (Cr), and tantalum (Ta). 
     The gate line assembly and the first light interception patterns  250  may be formed either with a single layer or with double or more layers. In the case of the double-layered structure, it is preferable that one layer is formed with a material having a low resistance while the other layer being formed with a material having a good contact characteristic. For instance, two layers based on chrome and aluminum or based on aluminum and molybdenum may be provided for the double-layered structure. 
     The gate line assembly and the first light interception patterns  250  are covered by a gate insulating layer  300 . The gate insulating layer  300  may be formed with silicon nitride. 
     A semiconductor layer  410  is formed on the gate insulating layer  300 , and two separate ohmic contact layers  520  and  530  are formed on the semiconductor layer  410  while centering around the gate electrode  210 . The semiconductor layer  410  may be formed with amorphous silicon, and the ohmic contact layers  520  and  530  with amorphous silicon into which n-type impurities such as phosphorus (P) are doped. 
     A data line assembly and second light interception patterns  650  are formed on the ohmic contact layers  520  and  530  and the gate insulating layer  300 . The data line assembly includes a plurality of data lines  610 , source electrodes  620  branched from the data lines  610 , drain electrodes  630  positioned opposite to the source electrodes  620  while centering around the gate electrode  210 , and data pads  640  connected to the end portions of the data lines  610  to receive picture signals from the outside and transmit them to the data lines  610 . The data line assembly and the second light interception patterns  650  are placed on the same plane, and formed together with a conductive metallic material such as aluminum (Al), aluminum alloy, molybdenum (Mo), molybdenum-tungsten alloy (MoW), chrome (Cr), and tantalum (Ta). 
     As in the gate line assembly and the first light interception patterns  250 , the data line assembly and the second light interception patterns  650  may be formed either with a single layer or with double or more layers. 
     The second light interception patterns  650  are positioned at the region between the gate pads  230  and the display area A as well as between the neighboring gate lines  200  such that they are not overlapped with the gate lines  200  and the gate pads  230 . Likewise, the first light interception patterns  250  are positioned at the region between the data pads  640  and the display area A as well as between the neighboring data lines  610  such that they are not overlapped with the data lines  610  and the data pads  640 . 
     A protective layer  700  is formed on the data line assembly, the second light interception patterns  650 , the semiconductor layer  410 , and the gate insulating layer  300 . The protective layer  700  may be formed with silicon nitride. The protective layer  700  has a contact hole  730  exposing the gate pad  230  together with the gate insulating layer  300 , a contact hole  740  exposing the data pad  640 , and a contact hole  720  exposing the drain electrode  630 . 
     Pixel electrodes  820 , subsidiary gate pads  830 , and subsidiary data pads  840  are formed on the protective layer  700  with a transparent material such as indium tin oxide (ITO). 
     Each pixel electrode  820  is connected to the drain electrode  630  via the contact hole  720 . The subsidiary gate pad  830  and the subsidiary data pad  840  are connected to the gate pad  230  and the data pad  640  via the contact holes  730  and  740 , respectively. The subsidiary gate and data pads  830  and  840  are provided to enhance adhesion between the gate and data pads  230  and  640  and the external circuits, and to protect the gate and data pads  230  and  640 . 
     An alignment layer  900  is formed on the protective layer  700  and the pixel electrodes  820 . In order to align the liquid crystal molecules, the alignment layer  900  may be surface-treated through rubbing or light illumination. 
     In the meantime, the color filter substrate  110  is overlaid with a black matrix  710 , and color filters  750  surrounded by the black matrix  710 . 
     An ITO-based common electrode  810  is formed on the black matrix  710  and the color filters  750 , and an alignment layer  910  is formed on the common electrode  810 . 
     The TFT array substrate is assembled with the color filter substrate  110  via a sealer  3 , and a liquid crystal LC is injected into the gap between the substrates. 
     As shown in  FIGS. 10 to 13 , the borderline of the color filter substrate  110  is indicated by the reference numeral  1 , and the borderline of the black matrix  710  indicated by the reference numeral  2 . The sealer  3  is positioned outside of the display area A, and the borderline  2  of black matrix  710  is disposed between the borderline  1  of the color filter substrate  110  and the sealer  3 . 
     In view of alignment errors, the first light interception patterns  250  are spaced apart from the data lines  610  by a minimum distance a, and the second light interception patterns  650  are spaced apart from the gate lines  200  by a minimum distance e. Furthermore, the first light interception patterns  250  are spaced apart from the data pads  640  by a reasonable distance b such that they are not overlapped with the data pads  640  as well as TCPs attached thereto in a reliable manner, and the second light interception patterns  650  are spaced apart from the gate pads  230  by a distance f. In addition, the first light interception patterns  250  are spaced apart from the sealer  3  by a distance c, and the second light interception patterns  650  are spaced apart from the sealer  3  by a distance g. As it is desirable that the first and second light interception patterns  250  and  650  do not have a gap with the black matrix  710 , they are overlapped with the black matrix  710  by a span d and h in view of the alignment errors. 
     In case the first and second light interception patterns  250  and  650  are overlapped with the gate and data lines  200  and  610 , short circuit may occur between them. Furthermore, in case the first and second light interception patterns  250  and  650  are overlapped with the sealer  3 , short circuit may also occur between them when the sealer  3  is compressed for the sealing purpose. In the above structure, even though a small gap exists between the light interception patterns  250  and  650  and the gate and data lines  200  and  610 , only negligible amount of light may leak there. 
     Such light interception patterns  250  and  650  may be also applied to in-plane switching (IPS) type liquid crystal displays where the common electrode and the pixel electrodes are formed at the TFT array substrate, and super twisted nematic (STN) liquid crystal displays where stripe-shaped electrodes cross over at the two substrates without TFTs. 
       FIGS. 14A to 17B  sequentially illustrate the steps of processing the TFT array substrate on a layer by layer base. 
     As shown in  FIGS. 14A and 14B , a gate line assembly  200 ,  210  and  230 , and first light interception patterns  250  are formed on an insulating substrate  100  through deposition and a first photolithography process. 
     Thereafter, as shown in  FIGS. 15A and 15B , a gate insulating layer  300 , a semiconductor layer  410  and an ohmic contact layer  510  are sequentially deposited onto the substrate  100 , and the ohmic contact layer  510  and the semiconductor layer  410  are patterned through a second photolithography process. 
     As shown in  FIGS. 16A and 16B , a data line assembly  610 ,  620 ,  630  and  640 , and second light interception patterns  650  are formed through deposition and a third photolithography process. Thereafter, the portion of the ohmic contact layer  510  exposed between the source electrode  620  and the drain electrode  630  is removed such that the ohmic contact layer  510  is separated into two portions  520  and  530  to expose the semiconductor layer  410 . 
     As shown in  FIGS. 17A and 17B , a protective layer  700  is deposited onto the substrate  100 , and patterned through a fourth photolithography to form contact holes  720 ,  730  and  740 . 
     Then, as shown in  FIGS. 12 and 13 , pixel electrodes  820 , subsidiary gate pads  830 , and subsidiary data pads  840  are formed at the substrate  100  through deposition and a fifth photolithography process. Thereafter, an alignment layer  900  is formed at the substrate  100 . 
     The TFT array substrate  100  is then assembled with the color filter substrate  110  via a sealer  3 , and a liquid crystal LC is injected into the gap between the substrates  100  and  110  to complete a liquid crystal panel. In case the alignment layer  900  of the TFT array substrate  100  overlaps the sealer  3 , the overlapped portion of the alignment layer  900  is set to be ⅕ of the width of the sealer  3 . 
     Thereafter, semiconductor circuits are mounted onto the liquid crystal panel. 
     First, an anisotropic conductive film (not shown) is formed at the exposed portion of the TFT array substrate  100  while covering the subsidiary gate and data pads  830  and  840 , and TCPs with semiconductor circuits are arranged at the TFT array substrate  100 , and thermal-compressed. In this case, the subsidiary pads  830  and  840  are electrically communicated with the TCPs via conductive balls contained in the anisotropic conductive film. This distance of b and f between the light interception patterns  250  and  650  and the pads  230  and  640  prevents possible short circuit via the conductive balls between the light interception patterns  250  and  650  and the subsidiary pads  830  and  840  during the thermal-compression. 
       FIGS. 18 to 20  illustrate a liquid crystal display according to a fifth preferred embodiment of the present invention. In this preferred embodiment, other components and structures of the liquid crystal display are the same as those related to the fourth preferred embodiment except that ohmic contact layers  520 ,  530  and  550  and semiconductor layers  410  and  450  are positioned under a data line assembly  610 ,  620 ,  630  and  640 , and second light interception patterns  650 . The shape of the ohmic contact layers  520 ,  530  and  550  is the same as that of the data line assembly  610 ,  620 ,  630  and  640  and the second light interception patterns  650 . The shape of the semiconductor layers  410  and  450  is the same as that of the data line assembly  610 ,  620 ,  630  and  640  and the second light interception patterns  650  except the portions between the source electrodes  620  and the drain electrodes  630 . 
     The fabrication process for the TFT array substrate is based on the four-mask photolithography. 
     First, a gate line assembly  200 ,  210  and  230  and first light interception patterns  250  are formed on an insulating substrate  100  through deposition and a first photolithography process. Thereafter, a gate insulating layer  300  is deposited onto the gate line assembly  200 ,  210  and  230  and the first light interception patterns  250  while covering them. Semiconductor layers  410  and  450 , ohmic contact layers  520 ,  530  and  550 , and a data line assembly  610 ,  620 ,  630  and  640  are sequentially deposited, and patterned through a second photolithography process. A protective layer  700  is deposited onto the substrate  100 , and patterned through a third photolithography process to thereby form contact holes  720 ,  730  and  740 . Thereafter, pixel electrodes  820 , subsidiary gate pads  830  and subsidiary data pads  840  are formed at the substrate  100  through deposition and a fourth photolithography process. Finally, an alignment layer is formed at the substrate  100 . 
     In the second photolithography process, a photoresist film is deposited onto the conductive layer for the data line assembly, and patterned through a mask differentiated in light transmission. The exposed portion of the conductive layer is removed while exposing the underlying ohmic contact layer. The exposed portion of the ohmic contact layer and the underlying semiconductor layer are etched, and the portion of the conductive layer between the source and drain electrodes  620  and  630  is removed. Thereafter, the exposed portion of the conductive layer between the source and drain electrodes  620  and  630  and the underlying ohmic contact layer are etched together. In this way, the semiconductor layers  410  and  450 , the ohmic contact layers  520 ,  530  and  550 , the data line assembly  610 ,  620 ,  630  and  640 , and the second light interception patterns  650  are formed at the substrate  100 . 
     In the resulting liquid crystal display, light interception patterns are provided at the TFT array substrate, and spaced apart from the electrode components of lines, pads, and a sealer so that leakage of light and short circuit can be effectively prevented. 
     While the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art will appreciate that various modifications and substitutions can be made thereto without departing from the spirit and scope of the present invention as set forth in the appended claims.

Technology Category: g