Abstract:
A method for forming a pattern, including the steps of preparing a cliché having a recess thereon corresponding to a position of a pattern, filling one of resist and ink within the recess of the cliché, affixing a substrate on which the pattern is to be formed on a loading plate, aligning the loading plate on the cliché, attaching the substrate on the loading plate to the cliché, and separating the substrate on the loading plate from the cliché.

Description:
[0001]    The present invention claims the benefit of Korean Patent Application No. 89294/2001 filed in Korea on Dec. 31, 2001, which is hereby incorporated by reference.  
         BACKGROUND OF THE INVENTION  
         [0002]    1. Field of the Invention  
           [0003]    The present invention relates to a method and apparatus for forming a pattern, and particularly, to a method and apparatus for forming a pattern capable of simplifying the fabrication process improving productivity when a liquid crystal display device is fabricated by a printing method.  
           [0004]    2. Discussion of the Related Art  
           [0005]    In general, a cathode-ray tube (CRT) monitor has been mainly used for displaying information in a TV and a computer. The CRT has a high image quality and high screen brightness, and thereby the CRT has been the main stream of the display devices. However, as the screen size is increased, the size and weight of the CRT monitor is greatly increased occupying a large space, and becoming impractical as a portable device.  
           [0006]    Flat panel display devices, such as a liquid crystal display (LCD), plasma display panel (PDP), organic electro luminescence (EL), light emitting diode (LED) and field emission display (FED), have been developed for solving the above problems. Among these flat panel display devices, the LCD is highlighted since it has been widely used in notebook PC&#39;s or computer monitors, and it has low power consumption.  
           [0007]    [0007]FIG. 1 is a cross-sectional view of a liquid crystal display device according to the related art. As shown in FIG. 1, the LCD device comprises an upper substrate  10 , a lower substrate  20  and a liquid crystal layer  30  formed therebetween. A color filter  11 , which generates colored light, comprising a black matrix  12  for preventing light leaking between pixels and a resin layer including dyes or pigments of red, green, and blue colors, and are formed on the upper substrate  10 . In addition, an over coat layer (not shown) may be formed on the color filter  1  for flattening the color filter  11  and improving bonding with an ITO, and a common electrode  13 , which is a transparent conductive material for applying a voltage to the liquid crystal layer  30 , are formed on upper part thereof. In addition, an alignment layer  14   a  for aligning liquid crystal molecules is formed on the common electrode  13 .  
           [0008]    A thin film transistor (T) and a pixel electrode  21 , which is an electrode corresponding to the common electrode  13 , are formed on the lower substrate  20 . The thin film transistor (T) comprises a gate electrode  15  to which a scan signal is applied, an active layer  16  for transmitting data signals corresponding to the scan signal, a gate insulating layer  17  for electrically isolating the active layer  16  and the gate electrode  15 , a source electrode  118   a  formed on an upper part of the active layer  16  for applying a data signal, and a drain electrode  18   b  for applying the data signal to a pixel electrode  21 . The active layer  16  comprises a semiconductor layer  16   a  formed by depositing amorphous silicon (a-Si), and an ohmic contact layer  16   b  n+-doped on both upper sides of the semiconductor layer  16   a.    
           [0009]    A passivation layer  19  for exposing a part of the drain electrode  18   b  is formed on the thin film transistor (T), and the pixel electrode  21  and the drain electrode  18   b  are electrically connected through the exposing portion. In addition, the pixel electrode  21  and the common electrode  13  are formed as transparent electrodes made of an ITO so that light can be transmitted, and a second alignment layer  14   b  for aligning the liquid crystal molecules is formed on an upper part of the pixel electrode  21 .  
           [0010]    In order to fabricate the liquid crystal display device discussed above, a plurality of thin film deposition processes, photolithography processes and etching processes should be repeated. In order to fabricate the thin film transistor (T), the color filter  11 , and the black matrix  12 , a photoresist pattern is formed by an exposure process using a photoresist or a mask, and an etching process is performed thereafter. However, the above processes for forming the photoresist pattern are complex, and cost for fabricating the mask is increased as the substrate is increased. Therefore, a printing method by which the patterned resist can be formed without the exposing process has been recently suggested.  
           [0011]    [0011]FIGS. 2A through 2D are cross sectional views of a method and apparatus for forming a pattern using a gravure offset printing method according to the related art. As shown in FIG. 2A, resist is applied onto a cliché  24  on which a recess  23  is formed, thereafter, a doctor blade  32  flattens the cliché on which the resist is applied. At that time, the resist  31  is formed in the recess  23 , and any other resist remaining on the area is removed.  
           [0012]    As shown in FIG. 2B, a roller  33  is rotated contacting the cliché  24 , and the resist  31  filled in the recess  23  of the cliché  24  is transferred onto the roller  33 .  
           [0013]    As shown in FIG. 2C, a substrate  10   a  on which a pattern will be formed is loaded on a lower part of the roller  33 , and the roller  33  is rotated to re-transfer the resist  31   a  onto the substrate  10   a.    
           [0014]    [0014]FIG. 2D shows the resist pattern  31  a formed on the substrate  10   a  through the above gravure offset printing process.  
           [0015]    [0015]FIG. 3 is a planar view of a gravure offset printing apparatus according to the related art. As shown in FIG. 3, in the gravure offset printing apparatus, the cliché  24 , on which the concave recess  23  is formed, and a stage  25 , on which the substrate  10   a  for forming the pattern is disposed, are integrally constructed. The roller  33  is provided for transferring the resist pattern onto the substrate  10   a  from the cliché  24 . The roller  33  can be rotated and reciprocated between the cliché  24  and the stage  25 , and the roller  33  stained with the resist filled in the cliché  24  transfers the resist pattern onto the substrate in one rotation.  
           [0016]    [0016]FIG. 4 is a cross-sectional view of the gravure printing apparatus taken along I-I′ of FIG. 3. The cliché  24 , on which the recess  23  is formed, and the stage  25  are integrally formed, and the roller  33  located on an upper part of the cliché  24  moves between the cliché  24  and the stage  25  to form the resist pattern on the substrate  10   a . In order to retransfer the resist transferred from the cliché  24  onto the substrate  10   a  in one try, a width of the roller  33  should be the same or more as that of the substrate. Therefore, the size of the roller increases as the size of the liquid crystal panel is increased, and thereby cost for fabricating the roller is increased. When the resist is transferred onto the roller  33  from the cliché, the resist is not smoothly separated from the recess of the cliché. Therefore, some resist remains in the recess, and the surface of the resist transferred to the roller is not flat. Thereby, a gap between the substrate and the resist is formed when the resist is re-transferred onto the substrate. When the substrate is etched in the etching process, etchant flows into the gap and the part is etched unnecessarily. Therefore, a fatal error may occur in the display device which requires a pattern of high precision. Also, the resist remaining on the roller should be cleaned regularly.  
         SUMMARY OF THE INVENTION  
         [0017]    Accordingly, the present invention is directed to a method and apparatus for forming a pattern using a printing method that substantially obviates one or more of the problems due to limitations and disadvantages of the related art.  
           [0018]    An object of the present invention is to provide simplified fabrication processes and a printing apparatus for transferring a resist pattern onto a substrate after attaching the substrate on a cliché without a roller.  
           [0019]    Additional features and advantages of the invention will be set forth in the description which follows, and in part will be apparent from the description, or may be learned by practice of the invention. The objectives and other advantages of the invention will be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings. To achieve these and other advantages and in accordance with the purpose of the present invention, as embodied and broadly described herein, there is provided a method for forming a pattern including the steps forming a recess on a cliché corresponding to a position of a pattern, filling one of resist and ink within the recess of the cliché, affixing a substrate on which the pattern is to be formed on a loading plate, aligning the loading plate on the cliché, attaching the substrate to the cliché, and separating the substrate from the cliché.  
           [0020]    In another aspect of the invention, there is provided a method for forming a pattern including the steps of forming a recess on a cliché corresponding to a position of a pattern to be formed, filling one of resist and ink within the recess of the cliché using a doctor blade, affixing a substrate on which the pattern will be formed on a loading plate, aligning the loading plate on the cliché, attaching the substrate to the cliché, and setting a temperature of the loading plate to be higher than a temperature of the cliché, separating the loading plate from the cliché, and separating the substrate from the loading plate.  
           [0021]    In another aspect of the invention there is provided an apparatus for forming a pattern including a cliché having at least one recess for forming a pattern, a loading plate including a vacuum chuck and a heater, and a substrate.  
           [0022]    It is to be understood that both the foregoing general description and the following detailed description, are exemplary and explanatory and are intended to provide further explanation of the invention as claimed. 
       
    
    
     BRIEF DESCRIRPTION OF THE DRAWINGS  
       [0023]    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:  
         [0024]    [0024]FIG. 1 is a cross-sectional view of a general liquid crystal display device according to the related art;  
         [0025]    [0025]FIGS. 2A through 2D are cross sectional views of a method for forming a pattern using a gravure offset printing method according to the related art;  
         [0026]    [0026]FIG. 3 is planar view of a gravure offset printing apparatus according to the related art;  
         [0027]    [0027]FIG. 4 is a cross sectional view of the gravure printing apparatus taken along I-I′ of FIG. 3;  
         [0028]    [0028]FIGS. 5A through 5G are cross sectional views of an exemplary method and apparatus for forming a pattern according to the present invention; and  
         [0029]    [0029]FIG. 6 is a planar view of an exemplary loading plate of a printing apparatus according to the present invention. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0030]    Reference will now be made in detail to the preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings.  
         [0031]    [0031]FIGS. 5A through 5G are cross sectional views of an exemplary method and apparatus for forming a pattern according to the present invention. As shown in FIG. 5A, resist (or ink)  131  may be applied on a cliché  124  on which a recess  123  of right angles is formed, and a doctor blade  132  may flatten the cliché  124  on which the resist is applied. In the area flattened by the doctor blade  132 , the resist (or ink) may be filled only in the recess  123  of the cliché, and the resist remaining in an area other than the recess is removed.  
         [0032]    In FIG. 5B, a substrate  130  on which a pattern will be formed may be mounted on a loading plate  150 . At that time, a metal for forming a pattern of a gate line and source/drain electrodes (or SiOx or SiNx) for forming a passivation layer may be formed on the substrate  130 . When the substrate  130  is mounted on the loading plate  150 , a vacuum chuck (not shown) formed on the loading plate  150  may uniformly affix the substrate  130  on the loading plate  150 . In addition, a heater (not shown) may be disposed on the loading plate  150  to heat the substrate  130  mounted on the loading plate  150 . A structure and function of the loading plate will be described in more detail as follows.  
         [0033]    [0033]FIG. 6 is a planar view of an exemplary loading plate of a printing apparatus according to the present invention. As shown in FIG. 6, the loading plate  150  may include the vacuum chuck  140  and the heater  141 . The vacuum chuck  140  may be formed to uniformly affix and flatten the substrate (not shown), and is operated on an entire surface of the substrate when the substrate is mounted on the loading plate  150 .  
         [0034]    As the size of substrates increases, bowing of the substrates may occur Accordingly, if a substrate is attached to the cliché  124  having a bow, pressures in parts where the cliché  124  and the substrate  130  contact may vary from each other, thereby causing inferiority on the pattern transferred onto the substrate  130 . Thus, the vacuum chuck  140  affixes the substrate  130  so that is does not fall down, and uniformly loads the substrate onto the loading plate  150 . Thus, the inferior pattern caused by the bowing of the substrate may be prevented.  
         [0035]    The heater  141  may be disposed for causing the resist (or ink) filled in the recess  123  to be easily separable from the cliché  124 , and may be attached to the substrate  130  by making use of a bonding difference between the resist and the recess. Since the adhesive characteristics of the resist is dependent upon temperature, the resist (or ink) may be easily separated from the cliché  124  and attached to the substrate  130  using the temperature difference between the cliché  124  and the substrate  130 .  
         [0036]    For transferring the resist (or ink) on the cliché  124  onto the substrate  130 , the bonding of the resist may be stronger for the substrate  130  than for the cliché  124  in order to separate the resist (or ink) from the cliché  124 . In general, the resist may be easily attached to a side of the cliché  124  having a higher temperature, whereby the resist (or ink) can be easily separated from the cliché  124  and attached to the substrate  130  if there is a temperature difference between the cliché  124  and the substrate  130 . When using resist (or ink) having a bonding property dependent upon higher temperatures, the temperature of the substrate may be higher than that of the cliché  124 , whereby, the resist (or ink) filled in the recess of the cliché  124  can be easily attached to the substrate  130  having the higher temperature. Thus, the heater (not shown) may be placed in the loading plate  150  for loading the substrate  130 , in order to increase the temperature of the substrate  130 . The temperature of the substrate  130  which is attached on the plate  150  may be increased indirectly by heating the plate  150  using the heater (not shown).  
         [0037]    In addition, as shown in FIG. 5C, in order to orient the substrate  130 , upon which the pattern is formed, to face downward, the loading plate  150  on which the substrate  130  is mounted may be overturned to change position of the substrate  130  and the loading plate  150 . Even if the position of the substrate  130  and the loading plate  150  is reversed, the substrate  130  may be attached evenly to the loading plate  150  by the vacuum chuck  140  formed on the loading plate  150 .  
         [0038]    In addition, as shown in FIG. 5D, the loading plate  150  may be mounted on the cliché  124  so that a surface of the cliché  124  upon which the resist is filled contacts the substrate  130 . Thereafter, the temperature of the substrate  130  may be increased higher than a temperature of the cliché  124  so that the resist (or ink)  131  filled in the recess of the cliché  124  can be separated and attached to the substrate  130 . At that time, the temperature of substrate  130  may be controlled by the heater (not shown) formed in the loading plate  150 . The temperature of the substrate  130  may be controlled by heating the loading plate  150  from outer side after attaching the cliché  124  and the loading plate  150  without the heater (not shown) in the loading plate  150 .  
         [0039]    In addition, as shown in FIG. 5E, when the loading plate  150  is separated from the cliché  124 , the resist (or ink) filled in the recess of the cliché  124  may separate from the cliché  124  and bond to the substrate  130 .  
         [0040]    As shown in FIG. 5G, the substrate  130  may be separated from the loading plate  150 , and the resist (or ink) pattern  131  a may be formed on the substrate  130 .  
         [0041]    As described above, the method for forming the pattern according to the present invention, the printing apparatus is constructed with only the cliché on which the recess is formed and the loading plate for flattening the substrate, and therefore, the space occupied by the apparatus is very small. And the processes for forming the pattern is simple, and thereby, the processing time and the cost can be reduced, and it is also advantageous for fabricating a panel of larger area.  
         [0042]    Also, the heater may be disposed in the loading plate to make the resist (or ink) be separated from the cliché easily, and therefore, the inferiority on the pattern can be prevented and the pattern can be formed precisely when comparing to the conventional method using the roller.  
         [0043]    It will be apparent to those skilled in the art that various modifications and variations can be made in the method for forming a pattern using the printing method of the present invention without departing from the spirit or scope of the invention. Thus, it is intended that the present invention cover the modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents.