Patent Publication Number: US-2007117280-A1

Title: Manufacturing liquid crystal display substrates

Description:
RELATED APPLICATIONS  
      This application claims priority of Korean Patent Application No. 2005-89856, filed Sep. 27, 2005, the entire contents of which are incorporated herein by reference.  
     BACKGROUND  
      This invention relates to methods and apparatus for manufacturing liquid crystal display (LCD) substrates, and more particularly, to methods and apparatus that simplify and enhance the reliability of the processes used to manufacture an LCD substrate.  
      An LCD displays an image by use of the optical characteristics of a liquid crystal material in which the molecules of the material are rearranged when electric fields are applied thereto. An LCD includes a display panel having an array substrate, an opposite substrate and a liquid crystal layer disposed between the array substrate and the opposite substrate. The array substrate includes a plurality of gate lines and a plurality of data lines that intersect but do not connect to the gate lines. The array substrate includes a plurality of pixel portions defined by the gate lines and the data lines. Each of the pixel portions includes a thin-film transistor (TFT) that functions as a switch. The TFT is electrically coupled to the gate lines, the data lines, and a pixel electrode.  
      Both the array substrate and the opposite substrate are typically manufactured with photolithography processes. The photolithography processes includes a photoresist (PR) coating process, a drying process, an exposing process, a developing process, a heat treatment process and an etching process. As display substrates becomes larger, the photolithography apparatus used for manufacturing the display substrate also becomes correspondingly larger, up to certain practical limits on the size of the apparatus.  
      Accordingly, there is a long felt but as yet unsatisfied need in the industry for new methods and apparatus for manufacturing large LCD substrates that are simple, inexpensive, and reliable in use.  
     BRIEF SUMMARY  
      In accordance with the exemplary embodiments thereof described herein, the present invention provides methods and apparatus for manufacturing large LCD substrates that are simpler, more efficient, and more reliable than the photolithographic methods and apparatus of the prior art.  
      In one exemplary embodiment of the present invention, an LCD substrate includes a plurality of pixel portions, each comprising a switching element electrically connected to a gate line and a source line, and a pixel electrode electrically connected to the switching element. An exemplary embodiment of a method for manufacturing the display substrate includes forming a gate electrode of the switching element on a base substrate, forming a gate insulating layer on the base substrate having the gate electrode, forming a source and drain electrode of the switching element on the gate insulating layer, forming a passivation layer on the base substrate having the source and the drain electrode formed thereon, radiating a laser beam onto the passivation layer to form a first contact hole that exposes a portion of the drain electrode, and forming the pixel electrode electrically connected to the drain electrode through the first contact hole.  
      An exemplary embodiment of an apparatus for manufacturing the display substrate in accordance with the present invention includes a head section, a head transferring section and a stage section. The head section emits a laser beam. The transferring section fixes the head section and moves it to selected positions. A display substrate including the insulating layer is disposed on the stage section and the insulating layer is patterned by the laser beam.  
      The methods and apparatus of the invention enable the process of manufacturing large LCD substrates to be simplified yet more reliable by patterning the insulating layer of the display substrate using the laser beam instead of using the photolithographic techniques of the prior art.  
      A better understanding of the above and many other features and advantages of the manufacturing methods and apparatus of the present invention and their advantageous application to the manufacture of LCD substrates may be obtained from a consideration of the detailed description of some exemplary embodiments thereof below, particularly if such consideration is made in conjunction with the appended drawings, wherein like reference numerals are used to identify like elements illustrated in one or more of the figures thereof. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       FIG. 1  is a partial upper side perspective view of an exemplary embodiment of an apparatus for manufacturing an LCD substrate in accordance with the present invention;  
       FIG. 2  is a partial upper side perspective view of a head section of the apparatus of  FIG. 1 ;  
       FIGS. 3A  to  3 C are partial upper side and cross-sectional views of the apparatus of  FIG. 1  being used in three exemplary patterning methods of the invention;  
       FIG. 4  is a partial upper side perspective view of the head section of an exemplary alternative embodiment of an apparatus for manufacturing an LCD substrate in accordance with the present invention;  
       FIGS. 5A  to  5 D are sequential partial cross-sectional views of an insulating layer on an LCD substrate being patterned with the alternative apparatus of  FIG. 4 ;  
       FIG. 6  is a partial plan view of an exemplary LCD substrate manufactured by the apparatus of  FIGS. 1 and 4 ;  
       FIGS. 7A  to  7 E are sequential partial cross-sectional views of the LCD substrate of  FIG. 6  corresponding to cross-sectional views taken along the section line I-I′ therein, showing the sequential steps of a first exemplary embodiment of a method for manufacturing the substrate in accordance with the present invention;  
       FIGS. 8A  to  8 D are sequential partial cross-sectional views of the LCD substrate of  FIG. 6  corresponding to cross-sectional views taken along the section line I-I′ therein, showing the sequential steps of a second exemplary embodiment of a method for manufacturing the substrate in accordance with the present invention; and,  
       FIG. 9  is a partial cross-sectional view of the display substrate  120  taken along the lines II-II′ in  FIG. 6  and illustrating the manufacture of the display substrate in accordance with another aspect of the present invention. 
    
    
     DETAILED DESCRIPTION  
      It should be understood that the exemplary embodiments of the present invention described below may be varied modified in many different ways without departing from the inventive principles disclosed herein, and the scope of the present invention is therefore not limited to these particular flowing embodiments. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the concept of the invention to those skilled in the art by way of example and not of limitation. Like reference numerals refer to like elements throughout.  
      It will be understood that when an element is referred to as being “on” another element, it can be directly on the other element or intervening elements may be present there between. In contrast, when an element is referred to as being “directly on” another element, there are no intervening elements present. As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items.  
      It will be understood that, although the terms first, second, third etc. may be used herein to describe various elements, components, regions, layers and/or sections, these elements, components, regions, layers and/or sections should not be limited by these terms. These terms are only used to distinguish one element, component, region, layer or section from another element, component, region, layer or section. Thus, a first element, component, region, layer or section discussed below could be termed a second element, component, region, layer or section without departing from the teachings of the present invention.  
      The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises” and/or “comprising,” or “includes” and/or “including” when used in this specification, specify the presence of stated features, regions, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, regions, integers, steps, operations, elements, components, and/or groups thereof.  
      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. For example, if the device in the figures is turned over, elements described as “below” or “beneath” other elements or features would then be oriented “above” the other elements or features. Thus, the exemplary term “below” can encompass both an orientation of above and below. The device may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly.  
      Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and the present disclosure, and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.  
      Embodiments of the present invention are described herein with reference to cross section illustrations that are schematic illustrations of idealized embodiments of the present invention. As such, variations from the shapes of the illustrations as a result, for example, of manufacturing techniques and/or tolerances, are to be expected. Thus, embodiments of the present invention should not be construed as limited to the particular shapes of regions illustrated herein but are to include deviations in shapes that result, for example, from manufacturing. For example, a region illustrated or described as flat may, typically, have rough and/or nonlinear features. Moreover, sharp angles that are illustrated may be rounded. Thus, the regions illustrated in the figures are schematic in nature and their shapes are not intended to illustrate the precise shape of a region and are not intended to limit the scope of the present invention.  
      Hereinafter, the embodiments of the present invention will be described in detail with reference to the accompanied drawings.  
       FIG. 1  is a partial upper side perspective view of an exemplary embodiment of an apparatus for manufacturing an LCD substrate in accordance with the present invention. With reference to  FIG. 1 , the apparatus includes a stage section  10 , a head section  30  and a transferring section  50 . The head section  30  is disposed above the stage section  10  so that a laser beam radiating from the former can be focused onto an object disposed on the latter. In  FIG. 1 , an LCD substrate  20  having an insulating layer on it that is to be patterned is disposed on the stage section  10  and supported by it. The head section  30  is arranged to radiate a laser beam  32  onto the substrate  20  so as to burn a desired pattern  21  into the insulating layer formed on the substrate  20  in the manner described below. The insulating layer may comprise a passivation layer or an organic insulating layer. The pattern  21  desired to be formed in the insulating layer may comprise, e.g., a bore or a through-hole having a selected depth and width.  
      The laser that generates the beam  32  may comprise, for example, an ultraviolet (UV) excimer laser, which patterns the insulating layer on the substrate  20  by a multiphoton absorption process. In one preferred embodiment, the UV excimer laser beam has a wavelength of about 193 nm (ArF) to about 351 nm (XeF), a maximum power of about 300 W, and a repetition rate (RR) of between from about 50 Hz to about 200 Hz. The UV excimer laser beam can form a pattern with a width and depth of about a 2 microns (1 μm=1×10 −6  meters), and accordingly, UV excimer laser beams are often used to form patterns in polymers, thin inorganic layers and the like by ablation. As used herein, the term “the laser beam” means a beam generated or produced by a UV excimer laser.  
      Although not illustrated in the figures, those of skill in the art will appreciate that the apparatus may be equipped with a plurality of head sections  30 , each equipped with a laser, which can reduce the amount of time involved in the manufacture of display substrates using the methods described herein.  
      With reference to  FIG. 1 , the transferring section  50  of the apparatus is capable of moving the head section  30  into selected positions with a selected speed, or “feed rate.” The feed rate is the velocity of horizontal movement of the head section  30  relative to a substrate work piece disposed below it, and is dependent on the performance level, i.e., ablation rate, of the apparatus. The head section  30 , which is fixed beneath the transferring section  50 , is moved by the transferring section to the selected position at which the desired patterns  21  are to be formed. By controlling the feed rate of the transferring section  50 , the head section  30  can burn or etch the insulating layer formed on the display substrate in a controllable manner and thereby form the desired pattern  21  more easily.  
       FIG. 2  is a partial upper side perspective view of the head section  30  of the apparatus of  FIG. 1 . Referring to both  FIGS. 1 and 2 , the head section  30  includes a light source part  31 , a mask  33  and a projection lens  35 . The light source part  31  generates the laser beam, concentrates it, and radiates the concentrated, high energy laser beam toward the mask  33 . The mask  33  includes an opening pattern  33   a  having a selected size and shape. The laser beam, which radiates from the light source part  31 , is modified by the mask  33  to incorporate a shape corresponding to the opening pattern  33   a  of the mask. The projection lens  35  serves to refract and focus the laser beam, modified with the shape of the mask&#39;s opening pattern  33   a , onto the display substrate  20 .  
       FIGS. 3A  to  3 C are partial upper side and cross-sectional views of the apparatus of  FIG. 1  being used to effect three different patterning methods of the invention.  
      In more detail,  FIG. 3A  is a partial upper side view illustrating a first exemplary patterning method of the invention. The desired pattern is formed by the laser beam, which is radiated by a head section  30   a , including a mask  33  having an opening pattern  33   a  therein. After a display substrate  20   a  which is to be patterned is disposed on the stage section  10   a , the head section  30   a  is moved to a first position above the substrate. Then, the insulating layer of the display substrate  20   a  is sequentially patterned by the laser beam, which is radiated from the head section  30   a  onto the substrate  20   a , to form a first hole-shaped pattern  21   a  in the layer. The head section is then moved in the direction of the arrow of  FIG. 3A  to a second position corresponding to a second hole-shaped pattern  21   a  to be formed, the pattern burned into the insulating layer, and so on, until all of the desired hole-shaped patterns  21   a  have been formed in the insulating layer of the substrate  20   a . The method of forming a plurality of hole-shaped patterns  21   a  described above may be advantageously employed, for example, in making contact holes that electrically connect a switching element with a pixel electrode of the display substrate  20   a.    
       FIG. 3B  is a partial upper side view illustrating a second exemplary patterning method according to the present invention. As in the above embodiment, the desired pattern is formed by a laser beam, which is radiated from a head section  30   b  including a mask  33  having an opening pattern  33   a  therein. As illustrated in  FIG. 3B , a display substrate  20   b  that is to be patterned is disposed on a stage section  10   b , and the head section  30   b  is moves from a starting position to a first position. The head section  30   b  is then moved over the substrate in the direction X of the arrow shown while the laser beam is being radiated, and the total length ‘L’ of the distance moved by the head section  30   b  is programmably controlled by a controller (not illustrated). This programmed movement of the radiating head  30   b  forms a pattern  21   b  having an elongated groove shape in the display substrate  20   b . The elongated groove-shaped pattern  21   b  formed by the above process may be used advantageously, for example, in making pad portions at the ends of wiring lines on a display substrate.  
       FIG. 3C  is a partial cross-sectional view illustrating an exemplary third patterning method according to the present invention. In this embodiment, the predetermined pattern is also formed by a laser beam that is radiated from a head section (not illustrated in  FIG. 3C ) that includes a slit mask  34  of the type illustrated. After a display substrate  20   c  that is to be patterned is disposed on a supporting stage section  10   c  of the apparatus, the head section is moved to a first position. Then, the insulating layer of the display substrate  20   c  is patterned with the laser beam radiating from the light source part of the head, as above. However, as will be understood by reference to  FIG. 3C , the laser beam comprises multiple portions that vary in intensity because the slit mask  34  includes openings that vary in area, such as the first opening pattern  33   b  and the second opening pattern  33 C shown in the figure.  
      In particular, the area of the first opening pattern  33   b  is substantially larger than that of the second opening pattern  33 C. Accordingly, the intensity of the laser beam passing through the first opening pattern  33   b  is substantially greater than that of the laser beam passing through the second opening pattern  33 C. Thus, as the head section is translated longitudinally over the substrate  20 C with the laser continuously radiating, the portion of the laser beam radiating through the first opening pattern  33   b  forms an elongated groove with a uniform depth and width on the display substrate  20   c , and the portion of the beam radiating through the second opening pattern  33   c  forms a pattern having a uniform gradient, or taper, on either side of the groove, as illustrated in the cross-sectional view of  FIG. 3C . From the foregoing, it may be seen that, by providing the head section with a slit mask  34 , a longitudinal groove pattern  21   c  having a uniform depth and tapered sidewalls is formed on the display substrate. As discussed below, when the pattern  21   c  is formed on a first region of the display substrate, and is repeatedly formed on a second region adjacent and peripheral to the first region, a peak-shaped pattern can be formed advantageously on the display substrate  20   c.    
       FIG. 4  is a partial upper side perspective view of the head section of an exemplary alternative embodiment of an apparatus for manufacturing an LCD substrate in accordance with the present invention. With reference to  FIG. 4 , the head section  130  includes a light source part  131 , a mask  133 , a diaphragm  135  and a projection lens  137 . The head section  130  and the diaphragm are arranged to move independently of each other along an x-axis, indicated by the arrow in  FIG. 4 .  
      As in the first embodiment above, the light source part  131  generates a laser beam, concentrates it, and radiates the concentrated, high energy laser beam in the direction of a substrate  120  disposed below it. As above, the mask  133  includes a plurality of opening patterns  133   a ,  133   b ,  133   c  and  133   d  having respective selected shapes and sizes, and the laser beam radiating from the light source part  131  is accordingly modified by the mask to have a shape corresponding to the plurality of the opening patterns  133   a ,  133   b ,  133   c  and  133   d  of the mask. The diaphragm  135  is disposed between the mask  133  and the light source part  131 , and is arranged to move along the x-axis shown. The diaphragm  135  functions to control the intensity of the laser beam radiating onto the mask  133  in the following manner.  
      In particular, moving the diaphragm  135  a first step, or distance, in the negative direction along the x-axis allows the laser beam to pass through only the first opening pattern  133   a  of the mask  133 , while blocking its passage through the remaining opening patterns thereof. Then, by moving the diaphragm  135  a second step in the negative direction along the x-axis allows the laser beam to pass through both the first and second opening patterns  133   a  and  133   b , while blocking its passage through the remaining openings. Moving the diaphragm  135  a third step in the negative x direction enables the laser beam to pass through the first, second and third opening patterns  133   a ,  133   b  and  133   c . Finally, moving the diaphragm  135  a fourth step in the negative direction along the x-axis allows the laser beam to pass through all four opening patterns  133   a ,  133   b ,  133   c  and  133   d  of the mask  133 . As will be understood, by moving the diaphragm  135  in the foregoing stepwise manner progressively increases the amount of time that the laser beam is allowed to radiate through the respective openings of the mask. Of course, in an alternative embodiment, the diaphragm  135  can be arranged to move in a positive direction along the x-axis, thereby progressively reducing the amount of time that the laser beam is allowed to radiate through the respective opening patterns of the mask  133 .  
      The projection lens  137  is disposed between the mask  133  and the display substrate  120  that is to be patterned, and serves to refract and focus the laser beam that has been shaped by the openings of the mask onto a substrate that is to be patterned.  
       FIGS. 5A  to  5 D are sequential partial cross-sectional views of an insulating layer disposed on an LCD substrate being patterned with the alternative embodiment of apparatus of  FIG. 4 . With reference to  FIGS. 4 and 5 A, the head section  130 , with the plurality of opening patterns  133   a ,  133   b ,  133   c  and  133   d  in the mask  133  thereof, is translated a first step in the positive direction along the x-axis shown in  FIG. 4 , and the diaphragm  135  is moved a first step in the negative direction along the x-axis shown in  FIG. 5 , so that the laser beam is allowed to pass through only the first opening pattern  133   a  of the mask. After the beam passes through the first opening pattern  133   a , it is focused onto the substrate  120  by the projection lens  137  for a selected period of time so as to form a first pattern  121   a  at a first groove position on the substrate, as shown in  FIG. 5A .  
      Referring to  FIGS. 4 and 5 B, the head section  130  is then moved a second step in the positive direction along the x-axis, and the diaphragm  135  is moved a second step in the negative direction along the x-axis, so that the laser beam passes through both the first and second opening patterns  133   a  and  133   b  of the mask  133 . After it passes through the first and second opening patterns  133   a  and  133   b  of the mask  133 , the laser beam is focused onto the substrate  120  by the projection lens  137  for a selected period of time so as to form the first and second patterns  121   a  and  121   b  at a second and the first groove positions, respectively.  
      As illustrated in  FIG. 5B , as a result of the above relative movements of the head section  130  and the diaphragm  135 , the second opening pattern  133   b  is located over the first groove position having the first pattern  121   a  previously formed therein, and the second pattern  121   b  corresponding to the second opening pattern  133   b  is then formed by the laser beam passing through the second opening pattern  133   b . The first opening pattern  133   a  is now disposed over the second groove position in which a pattern has yet to be formed, and the first pattern  121   a  corresponding to the first opening pattern  133   a  is then formed by the laser beam passing through the first opening pattern  133   a.    
      Referring to  FIGS. 4 and 5 C, the head section  130  with its mask opening patterns  133   a ,  133   b ,  133   c  and  133   d  is then moved a third step in the positive direction along the x-axis, and the diaphragm  135  is moved a third step in the negative direction along the x-axis, so that the laser beam is allowed to pass through the first, second and third opening patterns  133   a ,  133   b  and  133   c  of the mask  133 . As illustrated in  FIG. 5C , after it passes through the first, second and third opening patterns  133   a ,  133   b  and  133   c  of the mask  133 , the laser beam is focused onto the substrate  120  by the projection lens  137  for a selected period of time so as to form the patterns  121   a ,  121   b  and  121   c  at a third, the second and the first groove positions of the substrate, respectively.  
      As shown in  FIG. 5C , as a result of the foregoing respective, relative movements of the head section  130  and the diaphragm  135 , the third opening pattern  133   c  of the mask  133  is located over the first groove position having the first and second patterns  121   a  and  121   b  previously formed therein, and the third pattern  121   c  corresponding to the third opening pattern  133   c  is thus formed at the first groove position by the laser beam passing through the third opening pattern  133   c . The second opening pattern  133   b  of the mask  133  is disposed over the second groove position having the first pattern  121   a  previously formed therein, and the second pattern  121   b  corresponding to the second opening pattern  133   b  is then formed at the second groove position by the laser beam passing through the second opening pattern  133   b . The first opening pattern  133   a  of the mask  133  is located over the third groove position on which a pattern has yet to be formed, and the first pattern  121   a  corresponding to the first opening pattern  133   a  is then formed at the third groove position by the laser beam passing through the first opening pattern  133   a  of the mask  133 .  
      Referring to  FIGS. 4 and 5 D, the head section  130  and mask opening patterns  133   a ,  133   b ,  133   c  and  133   d  is then moved a fourth step in the positive direction along the x-axis, and the diaphragm  135  is moved a fourth step in the negative direction along the x-axis, so that the laser beam passes through all four opening patterns  133   a ,  133   b ,  133   c  and  133   d  of the mask  133 . After passing through all of the mask openings, the laser beam is focused onto the substrate  120  by the projection lens  137  for a selected period of time to form the patterns  121   a ,  121   b ,  121   c  and  121   d  at a fourth, the third, the second and the first groove positions, respectively.  
      As shown in  FIG. 5D , as a result of the respective, relative movements of the head section  130  and the diaphragm  135 , the fourth opening pattern  133   d  of the mask  133  is located over the first groove position having the first pattern  121   a , the second pattern  121   b  and the third pattern  121   c  previously formed therein, and the fourth pattern  121   d  corresponding to the fourth opening pattern  133   d  is then formed by the laser beam passing through the fourth opening pattern  133   d  of the mask  133 . The third opening pattern  133   c  is disposed over the second groove position having the first pattern  121   a  and the second pattern  121   b  previously formed therein, and the third pattern  121   c  corresponding to the third opening pattern  133   c  is then formed by the laser beam passing through the third opening pattern  133   c . The second opening pattern  133   b  is located over the third groove position having the first pattern  121   a  previously formed therein, and the second pattern  121   b  corresponding to the second opening pattern  133   b  is then formed by the laser beam passing through the second opening pattern  133   b . The first opening pattern  133   a  of the mask  133  is located over the fourth groove position on which a pattern has yet to be formed, and the first pattern  121   a  corresponding to the first opening pattern  133   a  is then formed by the laser beam passing through the first opening pattern  133   a.    
      After form-ing four patterns  121   a ,  121   b ,  121   c  and  121   d  on the substrate, the head section  130  is moved step-by-step in the positive direction along the x-axis with the diaphragm  135  opened, and forms a plurality of patterns on the display substrate  120  using the manufacturing process previously described. Since the laser beam has a Gaussian profile, all of the groove shape patterns are formed with respective sidewalls having substantially the same slope. The manufacturing process described above, which radiates the laser beam in a step-by-step fashion to form a single pattern, is sometimes referred to as a synchronized image scanning (SIS) process.  
      As discussed above, the insulating layer of the display substrate  120  may be patterned in a stepwise process by using a mask having different opening patterns, and the SIS process may also be used to manufacture the contact holes of the switching elements and the pad portions. Additionally, a wide variety of other shapes of patterns can be formed in accordance with the shape, size and number of opening patterns of the mask  133 .  
       FIG. 6  is a partial plan view of an LCD substrate  120  manufactured by the apparatus illustrated in  FIG. 1 , and illustrates a single representative pixel portion thereof. With reference to  FIG. 6 , the display substrate  120  includes a plurality of gate lines GLn- 1  to GLn, a plurality of source lines DLm- 1  to DLm and a plurality of pixel portions P defined by the gate lines GLn- 1  to GLn and the source lines DLm- 1  to DLm. The gate lines GLn- 1  to GLn are arrayed in a first direction and extend in a second direction. The source lines DLm- 1  to DLm are arrayed in the second direction and extend in the first direction, i.e., the gate and source lines are arranged generally orthogonal to each other.  
      Gate pad portions GP are formed at an end portion of the gate lines GLn- 1  to GLn and source pad portions SP are formed at an end portion of the source lines DLm- 1  to DLm. A switching element comprising a thin film transistor (TFT), a storage common line SCL, and a pixel electrode PE are also formed at the pixel portions P. The switching element TFT is electrically connected to an nth gate line GLn, an mth data line DLm and the pixel electrode PE.  
       FIGS. 7A  to  7 E are sequential cross-sectional views of the substrate  120  of  FIG. 6  corresponding to cross-sectional views taken along the section line I-I′ therein and illustrating the successive stages of a first exemplary embodiment of a method for manufacturing the display substrate in accordance with the present invention.  
      Referring to  FIGS. 6 and 7 A, a metallic gate layer is formed on a base substrate  101 . The metallic gate layer is patterned by using a first mask to form a plurality of metallic gate patterns, including the plurality of gate lines GLn- 1  to GLn, the gate electrode  111  of the switching element TFT, and the storage common line SCL, all concurrently with each other. A gate insulating layer  102  is then formed over the base substrate  101  and the metallic gate patterns formed thereon.  
      Referring to  FIGS. 6 and 7 B, a channel layer  112  is formed on the gate insulating layer  102 . The channel layer  112  includes an active layer  112   a  and an ohmic contact layer  112   b . The active layer  112   a  may be disposed between the gate insulating layer  102  and the ohmic contact layer  112   b . The active layer  112   a  includes amorphous silicon, and the ohmic contact layer  112   b  includes n+amorphous silicon with a dopant doped through an in-situ process. The channel layer  112  is then patterned to form a channel pattern CH on the gate electrode  111  of the switching element TFT using a second mask.  
      Referring to  FIGS. 6 and 7 C, a metallic source layer is formed on the base substrate  101  having the previously formed channel pattern CH thereon. The metallic source layer is patterned by using a third mask to concurrently form a plurality of metallic source patterns, including the source lines DLm- 1  to DLm, a source electrode  113  of the switching element TFT and a drain electrode  114  of the switching element TFT. A portion of the channel pattern CH, which is disposed between the source electrode  113  and the drain electrode  114 , is etched by using the source and drain electrodes  113  and  114  as a mask to form the ohmic contact layer  112   b.    
      With reference to FIGS.  1  to  7 D, an insulating layer  103  (referred to herein as a “passivation layer”) is formed on the base substrate  101  having the plurality of metallic source patterns previously formed thereon. The passivation layer  103  can comprise an inorganic material or an organic material and has a thickness of no more than about 4000 angstrom. The passivation layer  103  and the gate insulating layer  102  are then etched by a laser beam radiated from the apparatus illustrated in  FIG. 1  or  4  in the manner described above.  
      In particular, as shown in  FIGS. 3A and 7D , the laser beam LS 1  passing through the mask  33  having a circular opening pattern therein, etches the passivation layer  103  on the drain electrode  114  of the switching element TFT, thereby forming a first contact hole  117  through the passivation layer.  
      Then, as illustrated in  FIGS. 3B and 7D , the head section  30  of the apparatus is translated for a selected distance over the substrate with the laser beam LS 2  continuously radiating so as to etch through both the passivation layer  103  and the gate insulating layer  102  on the gate pad portion GP, thereby forming a second contact hole  152  having a length equal to the selected distance.  
      Using substantially the same method as described above, the laser beam LS 3  then etches the passivation layer  103  on the source pad portion SP to form a third contact hole  172  having a selected length.  
      Alternatively, as illustrated in  FIG. 3A , the gate insulating layer  102  and the passivation layer  103  may be patterned by a head section  30  having an opening pattern size and configuration corresponding to the size and configuration of the second and third contact holes  152  and  172 , respectively.  
      Alternatively, the first, second and third contact holes  117 ,  152  and  172  may be formed by the apparatus illustrated in  FIG. 4 . For example, a mask  133  having substantially the same shape of the opening pattern, as illustrated in  FIGS. 5A  to  5 D, may be used for forming the contact holes. In other words, the laser beam passing through a mask having substantially the same shape of the opening pattern serves to etch the passivation layer  103  in a step-by-step process to form the contact holes, as described above. Additionally, the laser beam passing through a selected mask opening pattern and controlled by the diaphragm as described above may be used to form the selected shape of the contact holes.  
      Referring to  FIGS. 6 and 7 E, the pixel electrode PE layer is formed on the passivation layer  103  where the first, second and third contact holes  117 ,  152  and  172  are patterned thereon. The pixel electrode PE includes an optically transparent and electrically conductive material, such as indium tin oxide (ITO), indium zinc oxide (IZO), indium tin zinc oxide (ITZO), or the like. The pixel electrode is formed such that it is respectively electrically connected to the drain electrode  114  through the first contact hole  117 , to a metallic gate pattern  151  in the gate pad portion GP through the second contact hole  152 , and to a metallic data pattern  171  in the source pad portion SP through the third contact hole  172 . The pixel electrode layer is then patterned by using a fourth mask to form the pixel electrode PE in the pixel portion P, a first pad electrode  153  in the gate pad portion GP, and a second pad electrode  173  in the source pad portion SP, all patterned concurrently with each other.  
       FIGS. 8A  to  8 D are sequential cross-sectional views of the display substrate  120  of  FIG. 6  corresponding to successive cross-sectional views taken along the section line I-I′ therein and illustrating the successive stages of a second exemplary embodiment of a method for manufacturing the substrate in accordance with the present invention.  
      Referring to  FIGS. 6 and 8 A, a metallic gate layer is formed on the base substrate  201 . The metallic gate layer is patterned using a first mask to concurrently form a plurality of metallic gate patterns comprising a plurality of gate lines GLn- 1  to GLn, a gate electrode on the switching element TFT and the storage common line SCL. A gate insulating layer  202  is then formed on the base substrate  201  and the plurality of metallic gate patterns formed thereon. The active layer  212   a  is formed on the gate insulating layer  202 , and the ohmic contact layer, including n+ amorphous silicon having dopant doped through an in-situ process, is formed on the active layer  212   a  to form a channel layer  212 . The channel layer  212  is then patterned using a second mask to form a channel pattern CH covering a portion of the gate electrode  211 .  
      Referring to  FIGS. 6 and 8 B, a metallic source layer is then formed on the base substrate  201  and the channel pattern CH formed thereon. The source metallic layer is then patterned by a third mask to concurrently form the metallic source patterns, including source lines DLm- 1  to DLm, a source electrode  213  of the switching element TFT, and a drain electrode  214  of the switching element TFT. A portion of the channel pattern CH disposed between the source electrode  113  and the drain electrode  114  is then etched using the source and drain electrodes  113  and  114  as a mask to form an ohmic contact layer  112   b.    
      Referring to  FIGS. 1, 6  and  8 C, a passivation layer  203  and an organic insulating layer  204  are sequentially formed on the base substrate  201  having the plurality of metallic source patterns formed thereon. The passivation layer  203  can comprise an inorganic or an inorganic insulating material, and has a thickness of no more than about 4000 angstrom, whereas, the organic insulating layer  204  has a thickness of about 2 μm to about 4 μm. The passivation layer  203  and the organic insulating layer  204  are then etched by the laser beam radiated from the apparatus illustrated in  FIGS. 1 and 4 .  
      In particular, as illustrated in  FIG. 3A , a laser beam passing through a mask  33  having a circular opening pattern therein etches the passivation layer  203  on the drain electrode  214  of the switching element TFT and the organic insulating layer  204  on the passivation layer  203  to form a first contact hole  217 . The first contact hole  217  may be also formed by the apparatus of  FIG. 4 . For example, as described above in connection with the manufacturing process of  FIGS. 5A  to  5 D, a mask  133  having an opening pattern with substantially the same shape as the desired contact hole may be used to form the contact hole. Alternatively, by adjusting the diaphragm  135  so that the laser beam passes through a selected opening pattern having the desired shape, the desired contact hole shape may be formed in both the passivation layer  203  and the organic insulating layer  204 . Then, by using the step-by-step manufacturing processes described above and illustrated in  FIGS. 3C and 5A  to  5 D, the laser beam passing through the appropriate opening pattern etches the gate insulating layer  202  formed on the gate pad portion GP, the passivation layer  203  and the organic insulating layer  201  to form a second contact hole  252 . Then, using substantially the same process by which the second contact hole  252  were formed, the laser beam etches the passivation layer  203  formed on the source pad portion SP and the organic insulating layer  204  to form a third contact hole  272 .  
      Referring to  FIGS. 6 and 8 D, the pixel electrode layer is formed on the organic substrate  204  with the first, the second and the third contact holes  217 ,  252  and  272  previously formed thereon. As above, the pixel electrode layer includes an optically transparent and electrically conductive material, such as indium tin oxide (ITO), indium zinc oxide (IZO), indium tin zinc oxide (ITZO), or the like. The pixel electrode is respectively electrically connected to the drain electrode  214  through the first contact hole  217 , a metallic gate pattern  251  in the gate pad portion GP through the second contact hole  252 , and a metallic data pattern  271  in the source pad portion SP through the third contact hole  272 . The pixel electrode layer is then patterned using a fourth mask to form concurrently the pixel electrode PE on the pixel portion P, a first pad electrode  253  on the gate pad portion GP, and a second pad electrode  273  on the source pad portion SP.  
      As may be noted from the above, the second contact hole  252  of the gate pad portion GP and the third contact hole  272  in the source pad portion SP in  FIG. 8C  are formed with “stepped portions.” In other words, an upper portion of each of the second and third contact holes  252  and  272  has a greater diameter than a diameter of a lower portion of each of the second and third contact holes  252  and  272 , respectively. As a result, electrical contact can easily be made between the second and third contact holes  252  and  272  and the output pads of an external device. Typically, the gate pad portion GP and the source pad portion SP are electrically connected to an output terminal of external equipment through an anisotropic conductive film (ACF). The stepped characteristic of the contact holes described above and the benefits thereof are disclosed in Korean Laid-Open Patent Publication No. 2002-63424, entitled “Liquid crystal display device and method for manufacturing the same.” 
       FIG. 9  is a partial cross-sectional view of the display substrate  120  taken along the lines II-II′ in  FIG. 6 , and illustrates another aspect of the methods for manufacturing the substrate in accordance with the present invention. Referring to  FIGS. 6 and 9 , the metallic gate layer is deposited on the base substrate  301  and patterned to concurrently form the plurality of metallic gate patterns, including the plurality of gate lines GLn- 1  to GLn, the gate electrode on the switching element TFT and the storage common line SCL, as above. A gate insulating layer  302  is then formed on the base substrate  301  and the plurality of metallic gate patterns formed thereon. The channel layer is then deposited and patterned on the gate insulating layer  302  to form the channel layer  112  layered on the gate electrode of the switching element TFT.  
      The metallic source layer is then deposited and patterned on the base substrate  301  with the channel layer  112  formed thereon to concurrently form the plurality of metallic source patterns, including the plurality of source lines DLm- 1  to DLm, the source electrode of the switching element TFT and the drain electrode of the switching element TFT.  
      A protective insulating layer or passivation layer 3 O 3  and an organic insulating layer  304  are then sequentially formed on the base substrate  301  and the plurality of metallic source patterns formed thereon. When an organic insulating layer  304  is formed on the base substrate  301 , the use of a passivation layer  303  is optional. The organic insulating layer  304 , the passivation layer  303  and the gate insulating layer  302  are then selectively etched using the apparatus illustrated in  FIGS. 1 and 4  to form a desired pattern therein. In particular, as illustrated in  FIG. 9 , the organic insulating layer  304  formed on the pixel portion P area is patterned to have a peaked shape. When the apparatus of  FIG. 1  is used, a slit mask  34  of the type illustrated in  FIG. 3C  may be used advantageously to pattern the organic insulating layer  304  to have the peaked shape illustrated in  FIG. 9 .  
      Additionally, when an apparatus of the type described above and illustrated in  FIGS. 5A  to  5 D is used, the organic insulating layer  304  may be patterned into the peaked shape using the SIS process described above.  
      In either case, the organic insulating layer  304  and the passivation layer  303  are respectively etched with the laser beam radiating from the light source part to form the first contact hole  117 , thereby exposing a small portion of the drain electrode of the switching element TFT, the second contact hole  152 , thereby exposing a small portion of the gate metallic layer of the gate pad portion GP, and the third contact hole  172 , thereby exposing a small portion of the source metallic layer of the source pad portion SP, respectively.  
      Then, the pixel electrode layer is deposited and patterned on the organic insulating layer  304  to form the pixel electrode PE, as above. The pixel electrode PE is then electrically connected with the drain electrode of the switching element TFT through the first contact hole. In addition, the first and the second pad electrodes are formed. The first pad electrode is connected with the metallic gate layer through the first contact hole  117 , and the second pad electrode is connected with the metallic source layer through the second contact hole  152 .  
      As will be appreciated, by patterning the organic insulating layer of the pixel portions P to incorporate the peaked shapes as described above and illustrated in  FIG. 9 , the alignment angle of the liquid crystal molecules disposed between the substrates of the LCD can be more readily controlled. Accordingly, the viewing angle, i.e., the range of angles at which an image on the LCD can be seen by a viewer thereof, can be substantially increased.  
      In accordance with the methods and apparatus of the present invention, by using a laser beam controllably radiated from a light source part of an apparatus to selectively pattern the insulating layer on an LCD substrate, the complicated apparatus and manufacturing methods of conventional photolithography techniques used in the past are substantially simplified. Furthermore, the reliability of the LCD manufacturing process is substantially enhanced by the precision with which the shapes and positions of the patterns can be formed by the apparatus and methods of the present invention.  
      By now, those of skill in this art will appreciate that many modifications, substitutions and variations can be made in and to the methods and apparatus of the present invention and their advantageous use in manufacturing LCD substrates without departing from its spirit and scope. In light of this, the scope of the present invention should not be limited to that of the particular embodiments illustrated and described herein, as they are only exemplary in nature, but instead, should be fully commensurate with that of the claims appended hereafter and their functional equivalents.