Abstract:
A pattern transcription apparatus comprises a cliche including a concave portion, a convex portion and a printing stopper, the printing stopper formed in the concave portion; and a blanket, on which a resist material layer is coated, rotatable on the cliche, wherein edges of the printing stopper protruding from the printing stopper to have a height greater than a top surface of the convex portion.

Description:
[0001]    The present application claims the benefit of Korean Patent Application No. 2007-0015264 filed in Korea on Feb. 14, 2007, which is hereby incorporated by reference in its entirety. 
       BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The present invention relates to a pattern transcription device, and more particularly, to a transcription device and a method of fabricating a cliche for the pattern transcription device being capable of forming a fine pattern without damages on the pattern. 
         [0004]    2. Discussion of the Related Art 
         [0005]    A flat panel display device, such as a liquid crystal display (LCD) device, includes a thin film transistor (TFT) as a switching element in each pixel. A fabricating process of the TFT requires many mask processes including a process of forming a photoresist pattern (PR). The PR pattern has a great effect on characteristics of the TFT. Characteristics of the TFT are the subject of significant research and development. Particularly, significant efforts have been devoted to improve characteristics of the TFT using a fine metal pattern. 
         [0006]    Generally, a fabricating process of the PR pattern includes a step of forming a PR layer by coating a photosensitive PR material, a step of exposing the PR layer using a mask and a step of developing the exposed PR layer to form the PR pattern. However, since many proces steps for fabricating the PR pattern, which are very complicated, are required to fabricate the TFT, production costs increase and production yield decreases. 
         [0007]    To resolves these problems, a method of fabricating a resist pattern using a printing method is suggested.  FIGS. 1A to 1D  show a process of fabricating a resist pattern by a conventional reverse offset method. First, as shown in  FIG. 1A , a resist material layer  32  is coated on an outer surface of a blanket  30 . The blanket  30  covers along a circumference of a roller  31 . The blanket  30  has a circumference being substantially the same as a length of a substrate, on which a resist pattern is to be formed. 
         [0008]    Next, as shown in  FIG. 1B , the blanket  30 , on which the resist material layer  32  is coated, is rotated on a cliche  20  on a printing table  40 . The cliche  20  includes a plurality of concave portions  22  and a plurality of convex portions  24  to resulting in an uneven surface. Each convex portion  24  is disposed between two adjacent concave portions  22 . When the roller  31  is rotated on the cliche  20 , a concave-counter pattern  34  is formed on the blanket  30  and a convex-counter pattern  36  is formed on the convex portion  24  because the resist material has a greater adhesive strength to the cliche  20  than the blanket  30 . Namely, portions of the resist material layer  32  corresponding to the convex portion  24  are transferred on the convex portion  24 , and the other portions of the resist material layer  32  corresponding to the concave portion  22  remains on the blanket  30 , thereby forming the concave-counter pattern  34  on the blanket  30 . 
         [0009]    Next, as shown in  FIG. 1C , the blanket  30  including the concave-counter pattern  34  contacts and is rotated on a process-object layer  11  disposed on a substrate  10 . Then, the concave-counter pattern  34  is transferred on the process-object layer  11 . By applying UV light to the concave-counter pattern  34  and hardening it, a resist pattern  38  is formed on the process-object layer  11 , as shown in  FIG. 1D . 
         [0010]    Generally, the blanket  30  is formed of an elastic material, such as silicon or rubber. Accordingly, when the blanket  30  is rolled on the cliché  20 , the blanket  30  is crushed and contacts a bottom surface of the concave portion  22  of the cliché  20  because of it&#39;s an elastic property, as shown in  FIG. 2A , such that the resist material is partially stick to the bottom surface of the concave portion  22  and the desired remained pattern  38  (of  FIG. 1D ) can not be obtained. In addition, when the blanket  30  is rolled on the cliché  20  and contacts a board between the concave portion  22  and the convex portion, the resist material layer  32  flows into the concave portion  22 , as shown in  FIG. 2B . Consequently, there are some undesired resist patterns on the process-object layer  11 , as shown in  FIG. 2C . These problems are easily caused as the resist pattern  38  is large in size. 
         [0011]    To resolve these problems, it is possible to form the concave portions more deep so as not to contact the blanket with the bottom surface of the concave portions. However, when the concave portion has a greater dept, there are losses on a critical dimension. The concave portion is formed by a wet-etching, which has isotropic properties, using an etchant. The greater depth the concave portion has, the greater width the concave portion has. Namely, the width is proportional to the depth. It is difficult to form a fine pattern with a great width. 
       SUMMARY OF THE DISCLOSURE 
       [0012]    Accordingly, the present invention is directed to a patterning transcription device and method of fabricating a cliché for the same that substantially obviates one or more of the problems due to limitations and disadvantages of the related art. 
         [0013]    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. 
         [0014]    To achieve these and other advantages and in accordance with the purpose of the present invention, as embodied and broadly described herein, a pattern transcription apparatus comprises a cliché including a concave portion, a convex portion and a printing stopper, the printing stopper formed in the concave portion; and a blanket, on which a resist material layer is coated, rotatable on the cliché, wherein edges of the printing stopper protruding from the printing stopper to have a height greater than a top surface of the convex portion. 
         [0015]    In another aspect of the present disclosure, a method of fabricating a cliché for a pattern transcription apparatus comprises forming a metal pattern on a substrate; etching the substrate using the metal pattern as an etching mask to form a concave portion and a convex portion; and forming a printing stopper in the concave portion, wherein edges of the printing stopper protruding from at least one of the convex portion and the printing stopper. 
         [0016]    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 DESCRIPTION OF THE DRAWINGS 
         [0017]    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. 
           [0018]      FIGS. 1A to 1D  show a process of fabricating a resist pattern by a conventional reverse offset method. 
           [0019]      FIG. 2A  is an enlarging view showing a concave portion contacting a resist material. 
           [0020]      FIG. 2B  is an enlarging view showing a concave portion contacting a resist material 
           [0021]      FIG. 2C  is a plane perspective view showing a process-objected layer having an undesired resist pattern. 
           [0022]      FIG. 3  is a perspective cross-sectional view of a cliché according to an embodiment of the present invention. 
           [0023]      FIGS. 4A to 4D  show a process of fabricating a resist pattern by a reverse offset method according to an embodiment of the present invention. 
           [0024]      FIG. 5  is an enlarged view showing an “A” region of  FIG. 4B . 
           [0025]      FIGS. 6A to 6G  are cross-sectional views showing a process of fabricating a cliché according to an embodiment of the present disclosure. 
       
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
       [0026]    Reference will now be made in detail to the embodiments, examples of which are illustrated in the accompanying drawings. 
         [0027]      FIG. 3  is a perspective cross-sectional view of a cliché according to an embodiment of the present invention. In  FIG. 3 , a cliché includes a plurality of concave portions  122 , a plurality of convex portions  124  between adjacent concave portions  122 , and a printing stopper  126  in each of the concave portions  122 . A top the printing stopper  126  and a top of the convex portion  124  make an even surface. Namely, the convex portion  124  protrudes from a bottom surface of the concave portion  122  by a thickness of the printing stopper  126 . 
         [0028]    Referring to  FIGS. 3 and 4A , the printing stopper  126  is formed of a material having a surface energy density smaller than that of a blanket  130 . For example, the printing stopper  126  is formed of teflon. First and second edges  128   a  and  128   b  of the printing stopper  126  protrudes from the top surface of the printing stopper  126 . Namely, each of the first and second edges  128   a  and  128   b  has a height greater from a bottom surface of the cliché  120  than both the printing stopper  126  and the convex portion  124 . Each of the first and second edges  128   a  and  128   b  has a height from the top surface of the printing stopper  126  about ½ to about ⅓ of a thickness of a resist material layer  132  coated on an outer surface of the blanket  130 . A fine pattern is obtained due to the first and second edges  128   a  and  128   b . It is explained with reference to  FIGS. 4A to 4D . 
         [0029]      FIGS. 4A to 4D  show a process of fabricating a resist pattern by a reverse offset method according to an embodiment of the present invention. First, as shown in  FIG. 4A , a blanket  130  covers along a circumference of a roller  131 , and a resist material layer  132  is coated on an outer surface of the blanket  130 . When the blanket  130  with roller  131  is rotated, a resist supplier  136  supplies a resist material to the outer surface of the blanket  130  such that the resist material layer  132  is uniformly formed on the outer surface of the blanket  130 . 
         [0030]    Next, as shown in  FIG. 4B , the blanket  130 , on which the resist material layer  132  is coated, contacts and is rotated on a cliché  120  formed on a printing table  140 . As explained with  FIG. 3 , the cliché  120  includes the plurality of concave portions  122  and the plurality of convex portions  124 . Each convex portion  124  is disposed between two concave portions  122 . Each of the concave portions  122  corresponds to a pattern that is desired to be formed on a substrate. In addition, the printing stopper  126  is formed in each concave portion  122  to prevent the resist material being printed on the concave portions  122 . The central top surface of the printing stopper  126  has substantially the same height from a bottom surface of the cliché  120  as the convex portion  124 . On the other hand, edges of the printing stopper  126  protrude from the top surface of the printing stopper  126 . Namely, the edges of the printing stopper  126  have a height greater than a top surface of the convex portion  124 . A material of the blanket  130  has a surface energy density with a range between 20 mJ/cm 2  and 23 mJ/cm 2 , while a material of printing stopper  126 , such as teflon, has a surface energy density with a range between 13 mJ/cm 2  and 18 mJ/cm 2 . In brief, a material of the printing stopper  126  has a surface energy density smaller than a material of the blanket  130 . This means that the resist material is much stickier with respect to the blanket  130  than the printing stopper  126 . Namely, the resist material has a first adhesive strength to the blanket  130  and a second adhesive strength, smaller than the first adhesive strength, to the printing stopper  126 . Moreover, the resist material has a third adhesive strength to the cliché  120 . The third adhesive strength is greater than the first and second adhesive strengths. Namely, a surface energy density of the blanket  130  is greater than that of the printing stopper  126  and smaller than that of the cliché  120 . Accordingly, when the blanket  130  contacts and is rotated on the cliché  120 , a convex-counter pattern  134   b  is formed on the convex pattern  124  and a concave-counter pattern  134  is formed on the blanket  130 . Namely, since the resist material layer  132  is much stickier to the cliché  120  than the blanket  130 , the resist material layer  132  on the blanket  130  is transferred to the convex portions  124  to form the convex-counter pattern  134   b  on the convex portion  124  when the resist material layer  132  contacts the cliché  120 . However, since the resist material layer  132  is much stickier to the blanket  130  than the printing stopper  126 , the resist material layer  132  on the blanket  130  is never transferred to the printing stopper  126  even if the resist material layer  132  contacts the cliché  120 . Accordingly, the concave-counter pattern  134  is formed on the blanket  130 . 
         [0031]    In this case, as shown in  FIG. 5 , which is an enlarged view showing an “A” region of  FIG. 4B , the edges  128   a  and  128   b  protrude from a central top surface of the printing stopper  126 . The protruding portion of the edges  128   a  and  128   b  has a height about ½ to about ⅓ of a thickness of the resist material layer  132 . The edges  128   a  and  128   b  is disposed at boundaries between the concave and convex portions  122  and  124 . Due to the edges  128   a  and  128   b , both the convex-counter pattern  134   b  and the concave-counter-pattern  134  are formed to have a desired fine pattern. 
         [0032]    Next, as shown in  FIG. 4C , the blanket  130  having a plurality of concave-counter patterns  134  contacts and rotated on a process-object layer  111  to from the plurality of concave-counter patterns  134  on the process-object layer  111  on a substrate  110 . Since the resist material is much stickier to the process-object layer  111  than the blanket  130 , the concave-counter patterns  134  on the blanket  130  are transferred onto the process-object layer  111  when the concave-counter patterns  134  contacts the process-object layer  111 . Since a circumference of the blanket  130  is substantially the same as a length of the substrate  110 , the plurality of concave-counter patterns  134  on the blanket  130  are wholly transferred onto the process-object layer  111  by a single rotation. 
         [0033]    Next, the concave-counter patterns  134  on the process-object layer  111  is irradiated by UV light and hardened to form resist patterns  134 a on the process-object layer  111 . 
         [0034]    The process-object layer  111  may be one of a metal layer, from which metal patterns, e.g., a gate electrode, a source electrode and a data electrode of a thin film transistor (TFT), are formed, and an insulating layer including one of silicon oxide and silicon nitride. The process-object layer  111  may be etched using the resist patterns  138  as an etching mask to form the metal patterns or a contact hole in the insulating layer. 
         [0035]    As explained above, since the printing stopper  126 , which is less sticky to the resist material than the blanket  130 , is formed on the concave portions  122  of the clicke  120 , the resist material is never transferred to the concave portions  122  even if the resist material on the blanket  130  contacting printing stopper  126 . Moreover, since the edges  128   a  and  128   b  of the printing stopper  126  protrude from the central top surface of the printing stopper  126 , it is prevented the resist material flowing into the concave portion  122 . Accordingly, a desired concave-counter pattern  134  is formed on the blanket  130  without a sticky portion on the printing stopper  126 . The problem in the related art is improved. 
         [0036]      FIGS. 6A to 6G  are cross-sectional views showing a process of fabricating a cliché according to an embodiment of the present disclosure. As shown in  FIG. 6A , a metal layer  212  is formed on a substrate  211  by depositing at least one metallic material selected from a metal group including molybdenum (Mo), chromium (Cr) and nickel (Ni). Next, as shown in  FIG. 6B , a photosensitive material layer  214  is formed on the metal layer  212  by depositing a photosensitive material such as photoresist. Next, a mask (not shown) having a transmitting portion and a blocking portion is disposed over the photosensitive material layer  214 . The transmitting portion has a relatively high transmittance so that light through the transmitting portion can completely change the photosensitive material layer  214  chemically. The blocking portion shields light completely. Namely, a transmittance of the transmitting portion is greater than that of the blocking portion. When the photosensitive material is a positive type, the blocking portion of the mask corresponds to a position that is desired to form a convex portion, and transmitting portion of the mask corresponds to a position that is desired to form a concave portion. If the photosensitive material is a negative type, locations of the blocking and transmitting portions of the mask are changed into each other. Then, the photosensitive material layer  214  is exposed through the mask (not shown) and developed to form a photosensitive material pattern  216 , as shown in  FIG. 6C . 
         [0037]    Next, as shown in  FIG. 6D , the metal layer  212  (of  FIG. 6C ) exposed through the photosensitive material patterns  216  is etched using the photosensitive material pattern  216  as an etching mask to form a metal pattern  218 . The metal pattern  218  corresponds to the photosensitive material pattern  216 . And then, the substrate  211  exposed through the metal patterns  218  is etched using the metal pattern  218  as an etching mask to form a plurality of concave portions  222 . Moreover, since the substrate  211  is etched to form the plurality of concave portions  222 , other portions of the substrate  211  protrude. The protruding portions are defined as a plurality of convex patterns  224   a . Next, as shown in  FIG. 6E , a low surface energy density material layer  225  is formed on the substrate  211  including photosensitive material pattern  216 . The low surface energy density material layer  225  is formed on both the photosensitive material pattern  216  and a bottom surface of the concave portions  222 . The low surface energy density material layer  225  is formed on not only the bottom surface of the concave portion  222  but also a side wall of the concave portion  222 . A height of the low surface energy density material layer  225  in the side wall from a bottom surface of the substrate  211  is higher than that in a central top surface. Namely, the side wall of the low surface energy density material layer  225  has the same height as the convex pattern  224   a , while the central top surface of the low surface energy density material layer  225  has a lower height than the convex pattern  224   a . The low surface energy density material layer  225  may include teflon. 
         [0038]    Next, the photosensitive material pattern  216  and the metal pattern  218  are removed from the substrate  211 . The low surface energy density material layer  225  on the bottom surface of the concave portions  222  is defined as a printing stopper  226 , as shown in  FIG. 6F . 
         [0039]    Next, as shown in  FIG. 6G , the convex patterns  224   a  (of  FIG. 6F ) is selectively etched. A portion of the convex patterns  224   a  after being selectively etched is defined as a convex portion  224 . As a result, a central top surface of the printing stopper has the same height as the convex portion  224 . While, edges  228   a  and  228   b  of the printing stopper  226  protrude from both the central top surface of the printing stopper and the convex portion  224 . The substrate  211  including the plurality of concave portions  222 , the plurality of convex portions  224  and the printing stopper  226  with the edges  228   a  and  228   b  protruding from the central top surface of the printing stopper  226  is called a cliché  220 . 
         [0040]    On other hand, a cliché may be formed without a metal layer  212  (of  FIG. 6A ) to decrease a process time and increase production yield. However, since a photosensitive material layer  214  (of  FIG. 6B ) has a poor adhesive strength to the substrate  211  (of  FIG. 6A ) of glass, it is difficult to obtain a fine pattern without the metal layer  212  (of  FIG. 6A ). 
         [0041]    In the present invention, a cliché includes a printing stopper of a low surface energy density material in a concave portion. Moreover, edges of the printing stopper protrude from a top surface of the printing stopper. Bt these features, desired resist patterns are obtained. 
         [0042]    It will be apparent to those skilled in the art that various modifications and variations can be made in the organic electroluminescent device and fabricating method thereof 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.