Abstract:
A mother substrate for a liquid crystal display comprises a plurality of active matrix arrays, test lines connected to the active matrix arrays, test pads connected to the test lines, and connection lines connecting test lines to each other.

Description:
[0001]    This application claims the benefit of Korea Patent Application No. 10-2009-0104372 filed on Oct. 30, 2009, the entire contents of which is incorporated herein by reference for all purposes as if fully set forth herein. 
       BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    This document relates to a mother substrate provided with a plurality of active matrix arrays and a manufacturing method thereof. 
         [0004]    2. Related Art 
         [0005]    A liquid crystal display (“LCD”) has been widely applied due to its lightweight, thin profile, lower power consumption driving, and so on. Such an LCD has been employed as a portable computer such as a notebook PC, an office automation device, an audio/video device, an indoor/outdoor advertisement display device or the like. 
         [0006]    Referring to  FIG. 1 , a lower glass substrate GLSL of the active matrix LCD is provided with data lines DL and gate lines GL intersecting each other. At the intersections of the data lines DL and the gate lines GL, TFTs (thin film transistors) and pixel electrodes, which are connected to each other, are arranged in a matrix. An upper glass substrate GLSU is provided with black matrices BM, color filters CF, and common electrodes COM. A lower polarizer is attached to a light incidence plane of the lower glass substrate GLSL, and an upper polarizer, having the light absorption axis perpendicular to the light absorption axis of the lower polarizer, is attached to a light emission plane of the upper glass substrate GLSU. In addition, alignment layers are formed having contact with a liquid crystal layer LC between the lower glass substrate GLSL and the upper glass substrate GLSU. 
         [0007]    In order to increase productivity of the LCD, a plurality of active matrix arrays are formed on a large-sized mother substrate together, and thereafter the active matrix arrays are divided into each other through a scribing process and a grinding process. 
         [0008]    In the course of thin film patterning on the mother substrate, static electricity is generated during the deposition process, the etching process, and so forth. If line materials formed on the mother substrate are metals with low resistance, the static electricity is easily applied to the active matrix arrays via the line materials. The static electricity deteriorates characteristics of elements in the active matrix arrays or causes dielectric breakdown. 
       SUMMARY OF THE INVENTION 
       [0009]    Embodiments of this document provide a mother substrate of a liquid crystal display and a manufacturing method thereof, capable of blocking static electricity generated during manufacturing of the mother substrate. 
         [0010]    According to an exemplary embodiment of this document, there is provided a mother substrate for a liquid crystal display, comprises a plurality of active matrix arrays; test lines connected to the active matrix arrays; test pads connected to the test lines; and first connection lines connecting test lines to each other. 
         [0011]    Each of the active matrix arrays may comprise a TFT array including data lines, gate lines intersecting the data lines, TFTs connected to the data lines and the gate lines, pixel electrodes connected to the TFTs, and storage capacitors connected to the pixel electrodes; a driving circuit unit sequentially supplying gate pulses to the gate lines; and LOG lines connecting the test lines to the driving circuit unit. 
         [0012]    Each of the active matrix arrays may further comprise second connection lines connecting the LOG lines to each other. 
         [0013]    According to an exemplary embodiment of this document, there is provided a method of manufacturing a mother substrate of a liquid crystal display, comprising forming a plurality of active matrix arrays, test lines connected to the active matrix arrays, test pads connected to the test lines, and first connection lines connecting the test lines to each other on the mother substrate, respectively; forming a passivation layer covering the plurality of active matrix arrays, the test lines, the test pad, and the connection lines on the mother substrate; and forming a first open hole disconnecting the first connection lines during an etching process of the passivation layer. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0014]    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: 
           [0015]      FIG. 1  is a perspective view schematically illustrating an LCD; 
           [0016]      FIG. 2  is a plan view illustrating a mother substrate of an LCD according to an embodiment of this document; 
           [0017]      FIG. 3  is an enlarged plan view illustrating the active matrix array shown in  FIG. 2 ; 
           [0018]      FIG. 4  is a plan view illustrating connection lines formed between test lines, and between LOG lines. 
           [0019]      FIG. 5  is a plan view illustrating connection lines removed during an etching process of a passivation layer; 
           [0020]      FIG. 6  is a sectional view taken along the line I-I′ in  FIG. 4  and shows an example where the connection lines are formed of gate metal patterns; 
           [0021]      FIG. 7  is a sectional view taken along the line I-I′ in  FIG. 5  and shows disconnection of the connection lines shown in  FIG. 6 ; 
           [0022]      FIG. 8  is a sectional view taken along the line I-I′ in  FIG. 4  and shows an example where the connection lines are formed of source/drain metal patterns; and 
           [0023]      FIG. 9  is a sectional view taken along the line I-I′ and shows disconnection of the connection lines shown in  FIG. 8 . 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0024]    Hereinafter, embodiments of this document will be described in detail with reference to the accompanying drawings. Like reference numerals designate like elements throughout the specification. In the following description, when a detailed description of well-known functions or configurations related to this document is determined to unnecessarily cloud a gist of the present invention, the detailed description thereof will be omitted. 
         [0025]    The LCD according to this document may be implemented, when classified by LC modes, by a TN (twisted nematic) mode, a VA (vertical alignment) mode, an IPS (in plane switching) mode, an FFS (fringe field switching) mode, or the like. In view of a structure, the LCD according to this document may be implemented by any other type, for example, such as a transmissive LCD, a transflective LCD, a reflective LCD, or the like. The transmissive LCD and the transflective LCD require a backlight unit. The backlight unit may be implemented by a direct type backlight unit or an edge type backlight unit. 
         [0026]    According to this document, during manufacturing the LCD, a plurality of active matrix arrays is formed together on a mother substrate  100  as shown in  FIG. 2 . 
         [0027]    In  FIGS. 2 and 3 , the mother substrate  100  is provided with a plurality of active matrix arrays  20 , a test pad  12 , and test lines  13 . 
         [0028]    Each of the active matrix arrays  20  is provided with a TFT array  10 , a driving circuit unit  11  for driving the TFT array  10 , and LOG (line on glass) lines  14 . The TFT array  10  is provided with data lines, gate lines intersecting the data lines, TFTs connected to the data lines and the gate lines, pixel electrodes connected to the TFTs, storage capacitors connected to the pixel electrodes, and so forth. The driving circuit unit  11  comprises gate driving circuits for sequentially gate pulses to the gate lines. The LOG lines  14  connect the test lines  13  to the driving circuit unit  11 . 
         [0029]    The test pads  12  have contact with a probe of an external test jig and supplies a test signal and a driving power output from the test jig to the test lines  13 . The test pad is formed at one edge of the mother substrate  100 . 
         [0030]    The test lines  13  are formed between the test pad  12  and the LOG lines  14 , and transmit the test signal and the driving power from the test pad to the LOG lines  14 . 
         [0031]    A thin film patterning process of the mother substrate  100  includes a plurality of deposition and etching processes, thereby forming thin film patterns in the TFT array  10 , the driving circuit unit  11  for driving the TFT array  10 , the LOG lines  14 , the test pad  12 , and the test lines  13 . 
         [0032]    In order to block static electricity generated during the deposition process and the etching process, in this document, connection lines  15  are formed between the test lines  13  so as to be connected to each other. Also, in this document, the connection lines  15  are formed between the LOG lines  14  so as to be connected to each other. Static electricity is dispersed through the connection lines  15  and thereby static electricity flowing towards the driving circuit unit  11  can be blocked. The connection lines  15  do not comprise diodes or transistor elements, but comprises only metal line patterns 
         [0033]    The connection lines  15  may be formed of gate line patterns and/or source/drain metal patterns. Thus, there is no need for a separate process for forming the connection lines  15 . 
         [0034]    The connection lines  15  are removed by an open hole which is formed during an etching process of a passivation layer as shown in  FIG. 5 . Transparent conductive patterns  16  are formed at both edges of the open hole  17 . The transparent conductive patterns  16  prevent remaining metals of the connection lines  15  from being exposed to air and thus the metals being oxidized. After the connection lines  15  are removed, the probe of the test jig has contact with the test pad  12 . When the test jig has contact with the test pad  12 , the active matrix arrays are all inspected at the same time. Following the inspection, the active matrix arrays are individually separated from each other through a scribing process and a grinding process. 
         [0035]    The mother substrate  100  in this document can be manufactured using the two-mask process, the three-mask process, or the four-mask process in the related art. An embodiment of a method of manufacturing the mother substrate  100  will be described by exemplifying the four-mask process. Of course, the mother substrate  100  may be manufactured using the two-mask process or the three-mask process. 
         [0036]      FIG. 6  is a sectional view illustrating an example where the connection lines  15  is formed of a gate metal pattern.  FIG. 7  is a sectional view illustrating disconnection of the connection lines  15  shown in  FIG. 6 . 
         [0037]    Referring to  FIGS. 6 and 7 , in a manufacturing method of the mother substrate according to a first embodiment, a gate metal layer is formed on the mother substrate  100  using a deposition method such as sputtering. The gate metal may be selected from an aluminum (Al) based metal including aluminum/neodymium (AlNd), molybdenum (Mo), copper (Cu), chrome (Cr), tantalum (Ta), titanium (Ti), or the like. 
         [0038]    The gate metal layer is patterned during a first photolithography process. The gate lines, gate electrodes and gate pads of the TFTs connected to the gate lines, in the TFT array  10 , and the like are formed of the gate metal pattern GM. Along with the gate metal pattern GM in the TFT array  10 , the gate metal pattern of the driving circuit unit  11 , and the gate metal pattern GM of the test lines  12  and the connection lines  15  are formed. 
         [0039]    Next, a gate insulating layer GI, a semiconductor layer, and a source/drain metal layer are consecutively deposited to cover the gate metal patterns GM. The gate insulating layer GI may be made of an inorganic insulating material such as silicon oxide (SiOx) or silicon nitride (SiNx). The source/drain metal may be selected from molybdenum (Mo), titanium (Ti) tantalum (Ta), molybdenum alloy, copper (Cu), or the like. The semiconductor layer and the source/drain metal layer are patterned together during a second photolithography process. The semiconductor pattern SEMI includes an amorphous silicon layer doped with no impurities and an ohmic contact layer doped with impurities. The data lines and the source/drain electrodes SDM(S) and SDM(D) in the TFT array  10 , and data pads are formed of source/drain metal pattern. Along with the source/drain metal pattern in the TFT array  10 , the source/drain metal pattern of the driving circuit unit  11  and the source/drain metal pattern of the test lines  12  are formed. 
         [0040]    Subsequently, a passivation layer PASSI covering the active matrix array  20 , the test pad  12 , and the test lines is deposited on the mother substrate  100 . The passivation layer PASSI may be made of inorganic insulating material the same as the gate insulating layer GI, acryl based organic compound with a small dielectric constant, or organic insulating material such as BCB (bebzocyclobutane) and PFCB (perfluorocyclobutane). 
         [0041]    Next, the passivation layer PASSI is etched during a third photolithography process. During the third photolithography process, as shown in  FIG. 7 , a contact hole CNT for exposing a portion of the drain electrode SDM(D) of the TFT of the active matrix array  20 , the open hole  17  for disconnecting the gate metal pattern GM of the connection lines  15 , and contact holes for exposing the gate metal pattern and the source/drain metal pattern of the test pad  12  are formed together. 
         [0042]    Thereafter, a transparent conductive layer covering the passivation layer PASSI is deposited and then the transparent conductive layer is patterned during a fourth photolithography process. The transparent conductive layer may be made of indium tin oxide (ITO), tin oxide (TO), indium tin zinc oxide (ITZO), or indium zinc oxide (IZO). The transparent conductive layer pattern comprises the pixel electrodes of the active matrix array  20 , top electrodes of the gate pads and the data pads, a top electrode of the test pad  12 , and top electrodes covering the edges of the open hole  17 . 
         [0043]      FIG. 8  is a sectional view illustrating an example where the connection lines  15  are formed of the source/drain metal patterns.  FIG. 9  is a sectional view illustrating disconnection of the connection lines  15  shown in  FIG. 8 . 
         [0044]    Referring to  FIGS. 8 and 9 , in a manufacturing method of a mother substrate according to a second embodiment of this document, the connection lines  15  are formed of the source/drain metal patterns SDM, and the connection lines  15  are disconnected during the etching process of the passivation layer PASSI. The order of the manufacturing processes is substantially the same as in the above-described first embodiment. 
         [0045]    As described above, in this document, the test lines on the mother substrate are connected to each other using the connection lines, and the connection lines are disconnected during the etching process of the passivation layer, thereby blocking static electricity generated during the deposition process, the etching process, and so forth, by using the connection lines. 
         [0046]    Although embodiments have been described with reference to a number of illustrative embodiments thereof, it should be understood that numerous other modifications and embodiments can be devised by those skilled in the art that will fall within the scope of the principles of this disclosure. More particularly, various variations and modifications are possible in the component parts and/or arrangements of the subject combination arrangement within the scope of the disclosure, the drawings and the appended claims. In addition to variations and modifications in the component parts and/or arrangements, alternative uses will also be apparent to those skilled in the art.