Patent Publication Number: US-2012037018-A1

Title: Pattern transfer device and pattern transfer method

Description:
This application claims priority from and the benefit of Korean Patent Application No. 10-2010-0076908, filed on Aug. 10, 2010, which is hereby incorporated by reference for all purposes as if fully set forth herein. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     Exemplary embodiments of the present invention relate to a pattern transfer device and a pattern transfer method. 
     2. Description of the Background 
     Electronic display devices play an increasingly important role in today&#39;s information society, and various kinds of electronic display devices are widely used in diverse industrial fields. 
     As semiconductor technology advances, there is an increasing demand for electronic devices with low driving voltage, low power consumption, light weight, and compact sizes. Accordingly, there is a need to fabricate slimmer and lighter flat panel display devices having low driving voltage and low power consumption. To fabricate flat panel display devices, a micro-pattern formation process may be required. A printing process has been increasingly used for the micro-pattern formation process. 
     SUMMARY OF THE INVENTION 
     Exemplary embodiments of the present invention provide a pattern transfer device which can improve the flatness of a printing plate or a substrate when the printing plate or the substrate is loaded in the pattern transfer device. 
     Exemplary embodiments of the present invention also provide a pattern transfer method which improves the flatness of a printing plate or a substrate when the printing plate or the substrate is loaded in a pattern transfer device. 
     Additional features 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. 
     Exemplary embodiments of the present invention provide a pattern transfer device including a printing plate stage, a substrate stage, a pressure unit, and a printing unit. A printing plate including a pattern is disposed on the printing plate stage. A substrate is disposed on the substrate stage. The pattern formed on the printing plate is to be printed on the substrate. The pressure unit applies pressure to the printing plate. The pressure unit is disposed on the printing plate stage. The printing unit transfers the pattern formed on the printing plate to the substrate. 
     Exemplary embodiments of the present invention also provide a pattern transfer device including a printing plate stage, a substrate stage, a pressure unit, and a printing unit. A printing plate including a pattern is disposed on the printing plate stage. A substrate is disposed on the substrate stage. The pattern formed on the printing plate is to be printed on the substrate. The pressure unit applies pressure to the substrate. The pressure unit is disposed on the substrate stage. The printing unit transfers the pattern formed on the printing plate to the substrate. 
     Exemplary embodiments of the present invention also provide a pattern transfer method including disposing a printing plate on a printing plate stage. The printing plate includes a pattern. The method further includes measuring a flatness of the printing plate disposed on the printing plate stage, and changing, by using a pressure unit, the flatness of the printing plate by applying pressure to the printing plate disposed on the printing plate stage. The method further includes transferring, to a substrate, the pattern formed on the printing plate having a changed flatness. 
     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 
       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 exemplary embodiments of the invention, and together with the description serve to explain the principles of the invention. 
         FIG. 1  is a cross-sectional view of a pattern transfer device according to exemplary embodiments of the present invention. 
         FIG. 2  is a diagram illustrating a printing plate stage and a pressure unit according to exemplary embodiments of the present invention. 
         FIG. 3  is a diagram illustrating the process of loading a printing plate on the printing plate stage according to exemplary embodiments of the present invention. 
         FIG. 4  is a diagram illustrating the relationship between the pressure unit and the flatness profiles and regions of the printing plate according to exemplary embodiments of the present invention. 
         FIG. 5  is a diagram illustrating the operation of the pressure unit according to exemplary embodiments of the present invention. 
         FIG. 6  is a flowchart illustrating a pattern transfer method according to exemplary embodiments of the present invention. 
         FIG. 7  and  FIG. 8  are diagrams illustrating flatness measuring devices which measure the flatness of a printing plate according to exemplary embodiments of the present invention. 
         FIG. 9 ,  FIG. 10 ,  FIG. 11 ,  FIG. 12 , and  FIG. 13  are diagrams illustrating the process of transferring patterns formed on the printing plate to a substrate according to exemplary embodiments of the present invention. 
         FIG. 14  is a cross-sectional view of a pattern transfer device according to exemplary embodiments of the present invention. 
         FIG. 15  is a diagram illustrating a printing plate stage and a pressure unit according to exemplary embodiments of the present invention. 
         FIG. 16  is a diagram illustrating the relationship between the pressure unit and the flatness profiles and regions of a substrate according to exemplary embodiments of the present invention. 
         FIG. 17  is a diagram illustrating the operation of the pressure unit according to exemplary embodiments of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS 
     Advantages and features of exemplary embodiments of the present invention and methods of accomplishing the same may be understood more readily by reference to the following detailed description of exemplary embodiments and the accompanying drawings. The present invention may, however, be embodied in many different forms and should not be construed as being limited to the exemplary embodiments set forth herein. Rather, these exemplary 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. In the drawings, the size and relative sizes of layers and regions may be exaggerated for clarity. Like reference numerals in the drawings refer to like elements throughout the specification. 
     It will be understood that when an element or layer is referred to as being “on” another element or layer, the element or layer can be directly on another element or layer or intervening elements or layers may also be present. In contrast, when an element is referred to as being “directly on” another element or layer, there are no intervening elements or layers present. As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items. 
     Spatially relative terms, such as “below”, “beneath”, “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 drawings. 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 drawings. 
     Exemplary embodiments of the invention are described herein with reference to plan and cross-section illustrations that are schematic illustrations of exemplary embodiments of the 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, exemplary embodiments of the 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. Thus, the regions illustrated in the drawings are schematic in nature and their shapes do not necessarily illustrate the actual shape of a region of a device and are not intended to limit the scope of the invention. 
     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 will not be interpreted in an idealized or overly formal sense unless expressly so defined herein. 
     Hereinafter, a packet transfer device and a pattern transfer method according to exemplary embodiments of the present invention will be described with reference to the attached drawings. 
     A pattern transfer device according to exemplary embodiments of the present will now be described with reference to  FIG. 1 ,  FIG. 2 ,  FIG. 3 ,  FIG. 4 , and  FIG. 5 . 
       FIG. 1  is a cross-sectional view of a pattern transfer device  1  according to exemplary embodiments of the present invention.  FIG. 2  is a diagram illustrating a printing plate stage  10  and a pressure unit  100 .  FIG. 3  is a diagram illustrating the process of loading a printing plate  12  on the printing plate stage  10 .  FIG. 4  is a diagram illustrating the relationship between the pressure unit  100  and the flatness profiles and regions of the printing plate  12 .  FIG. 5  is a diagram illustrating an operation of the pressure unit  100 . 
     Referring to  FIG. 1 , the pattern transfer device  1  may include the printing plate stage  10 , a substrate stage  20 , the pressure unit  100 , and a printing unit  30 . 
     The printing plate  12 , on which patterns of a predetermined shape may be formed, may be loaded on a top surface of the printing plate stage  10 . The printing plate stage  10  may include a printing plate fixing unit (not shown) which fixes the printing plate  12  in place in order to prevent the movement of the printing plate  12  during a process. In general, the printing plate stage  10  may be a platform on which the printing plate  12  is affixed or hosted for applying a programmed pattern on to the printing plate  12 . 
     The printing plate  12  loaded on the top surface of the printing plate stage  10  may have predetermined patterns which are to be transferred to a substrate  22 . The printing plate  12  may be any suitable shape, including for example, a rectangular shape (e.g., a plate-shape). The printing plate  12  may be replaced for a pattern transfer process. When the pattern transfer process is performed successively, the printing plate  12  fixed onto the printing plate stage  10  can be used continuously. In general, the printing plate  12  may be made of any suitable material. For example, in some cases, the printing plate  12  may be made of an insulator such as glass. 
     The substrate stage  20  may be separated from the printing plate stage  10  by a predetermined gap and may be placed parallel to the printing plate stage  10 , as shown in  FIG. 1 . In general, the substrate stage  20  may be a platform on which the substrate  22  is affixed or hosted. The substrate  22  may be mounted on the substrate stage  20 . A height of the substrate stage  20  may be adjusted such that a top surface of the printing plate  12  is at substantially the same height as a top surface of the substrate  22  loaded on the substrate stage  20 . The substrate  22  may be made of any suitable material, and in some cases, may be a substrate used to make a flat panel display. 
     The substrate stage  20  and the printing plate stage  10  may be fixed and coupled to a main frame  40  such that the positions of the substrate stage  20  and the printing plate stage  10  remain unchanged during a pattern transfer process. During preparation for the pattern transfer process, the positions of the substrate stage  20  and the printing plate stage  10  on the main frame  30  can be changed. However, once the substrate stage  20  and the printing plate stage  10  are fixed at specific positions on the main frame  40 , the substrate stage  20  and the printing plate stage  10  may be coupled to the main frame  40  such that they cannot move during a process. In general, the main frame  40  may be any suitable housing unit for housing the printing plate stage  10  and the substrate stage  20 . 
     The printing unit  30  may transfer patterns formed on the printing plate  12  to the substrate  22  and may shuttle between the printing plate stage  20  and the substrate stage  10 . The printing unit  30  may include an input supply unit  31 , an ink-filling blade  32 , a remaining ink-removing blade  33 , a transfer roll  34 , a housing  35 , and a horizontal movement unit (not shown). Movement of the printing unit  30  may be controlled by the horizontal movement unit, as described in further detail below. 
     The ink supply unit  31  may supply a predetermined amount of ink onto the top surface of the printing plate  12  loaded on the printing plate stage  10 . The ink supply unit  31  can supply ink to any position on the printing plate  12 . In some cases, as shown in  FIG. 1 , the ink supply unit  31  may supply ink onto a front end of the printing plate  12  so as to facilitate a subsequent ink-filling process. The amount of ink supplied to the printing plate  12  may vary based on the type of printing plate  12 . In general, any necessary amount of ink may be provided on the printing plate  12 . 
     The ink-filling blade  32  may fill pattern grooves  14  formed on the top surface of the printing plate  12  with ink. In general, the ink-filling blade  32  may be any suitable shape or length. In some cases, the ink-filling blade  32  may have a length corresponding to a width of the printing plate  12 . The ink-filling blade  32  may be separated from the top surface of the printing plate  12  by a predetermined gap. The ink-filling blade  32  may move horizontally and may disperse ink, which is applied onto the top surface of the printing plate  12  by the ink supply unit  31 , over the top surface of the printing plate  12  according to a predetermined thickness. In some cases, the ink may be evenly spread over the top surface of the printing plate  12 , and the pattern grooves  14  formed on the top surface of the printing plate  12  may be filled with the ink. 
     The remaining ink-removing blade  33  may remove ink that remains after filling the pattern grooves  14  from the top surface of the printing plate  12 . The remaining ink-removing blade  33  may have any suitable shape, and, in some cases, may have a shape similar to that of the ink-filling blade  32 . However, the position of the remaining ink-removing blade  33  may be different from that of the ink-filling blade  32 . While the ink-filling blade  32  is separated from the top surface of the printing plate  12  by a predetermined gap, the remaining ink-removing blade  33  may contact the top surface of the printing plate  12 . Therefore, the remaining ink-removing blade  33  can remove ink that remains after filling the pattern grooves  14  of the printing plate  12  from the top surface of the printing plate  12 . 
     To fill the pattern grooves  14  with ink, the ink-filling blade  32  may be installed such that its top end tilts in a direction in which the ink-filling blade  32  moves horizontally, as shown in  FIG. 1 . On the other hand, to remove ink, the remaining ink-removing blade  33  may be installed such that its top end tilts in a direction opposite to a direction in which the remaining ink-removing blade  33  moves horizontally. 
     The transfer roll  34  may rotate when in contact with the top surface of the printing plate  12  or the main frame  40 . Ink filling the pattern grooves  14  may be transferred to a surface of the transfer roll  34  when the transfer roll  34  rotates on the printing plate  12 . The transfer roll  34  may then print the transferred ink on the top surface of the substrate  22 . As shown in  FIG. 1 , the transfer roll  34  may include a cylindrical roller  34   a  surrounded by a blanket  34   b  having a predetermined thickness. The blanket  34   b  may be a type of cover and may wrap around a surface of the roller  34   a . The blanket  34   b  may be made of a material to which ink that fills the pattern grooves  14  of the printing plate  12  can be easily attached. In addition, the blanket  34   b  may have some elasticity to be able to easily contact ink that fills the pattern grooves  14  of the printing plate  12 . 
     The housing  35  may accommodate the ink supply unit  31 , the ink-filling blade  32 , the remaining ink-filling blade  33 , and the transfer roll  34 . Accordingly, the housing  35  can integrate the ink supply unit  31 , the ink-filling blade  32 , the remaining ink-removing blade  33 , and the transfer roll  34 . 
     The horizontal movement unit (not shown) may horizontally move the housing  35 . As the horizontal movement unit horizontally moves the housing  35 , elements installed within the housing  35  may also move horizontally. The printing unit  30  may move in a predetermined direction (hereinafter, referred to as a ‘printing direction’), for example, moving from above the printing plate  12  to above the substrate  22  in the process of filling the printing plate  12  with ink and transferring the patterns on the substrate  22 . Accordingly, the horizontal movement unit may move the printing unit  30  horizontally to perform a process. 
     A printing unit aligner (not shown) may horizontally move the printing unit  30  in a direction (hereinafter, referred to as an ‘alignment direction’) perpendicular to a direction in which the printing plate stage  10  and the substrate stage  20  are arranged. Movement along the alignment direction may facilitate determining a position on the substrate to which a pattern is to be transferred. 
     Referring to  FIG. 2 ,  FIG. 3 ,  FIG. 4 , and  FIG. 5 , the pressure unit  100  may include a plurality of pressure members  110  to locally apply pressure to the printing plate  12 . The plurality of pressure members  110  may be arranged in any suitable manner. For example, in some cases, the plurality of pressure members  110  may be arranged in a grid-like formation and each pressure member  110  may be equally spaced from one-another, as shown in  FIG. 2 . In some cases, the distance between various pressure members  110  may vary. To apply pressure to the printing plate  12 , the pressure unit  100  may be configured with the printing plate stage  10  on which the printing plate  12  is loaded. For example, in some cases, the pressure unit  100  may be integrated with the printing plate stage  10 , and, in some cases, the pressure unit  100  may be attached to the printing plate stage  10  in any suitable manner. 
     In some cases, the printing plate  12  may be loaded on the printing plate stage  10  to overlap the pressure unit  100 . The pressure unit  100  may be driven in a direction from the top surface of the printing plate stage  10 , on which the printing plate  12  is placed, to the printing plate  12 , so that the pressure members  110  of the pressure unit  100  can deliver pressure to the printing plate  12 . The pressure members  110  may be, for example, pressure bars or pressure pins. Accordingly, each of the pressure pins may be driven in the direction from the printing plate stage  10  to the printing plate  12 , thereby applying a predetermined pressure to the printing plate  12 . 
     While the printing plate  12  may be plate-shaped, the printing plate  12  may not always have uniform flatness across its entire surface. There are various reasons for this. For example, the surface of the printing plate  12  may be partially bent or curved when the printing plate  12  is formed, or different external forces may be applied locally to the surface of the printing plate  12  when the printing plate  12  is loaded on the printing plate stage  10 . 
     Referring to  FIG. 4 , the printing plate  12  may have a plurality of flatness profiles for the above-mentioned reasons. In addition, a plurality of regions may be defined in the printing plate  12  to correspond to the various flatness profiles, respectively. The number of the regions of the printing plate  12  may correspond to the number of the pressure members  110  of the pressure unit  100  so that a different pressure can be applied to each region of the printing plate  12  according to the flatness of each region. 
     In  FIG. 4 , reference numeral  131  indicates a first flatness profile, reference numeral  132  indicates a second flatness profile, and reference numeral  133  indicates a third flatness profile. In addition, reference numeral  121  indicates a first region having the first flatness profile  131 , reference numeral  122  indicates a second region having the second flatness profile  132 , and reference numeral  123  indicates a third region having the third flatness profile  133 . 
     Reference characters A- 1  through E- 1  indicate the difference in surface height according to the flatness profile of the printing plate  12 . The surface height of the printing plate  12  increases in the order of E- 1  to A- 1 . For example, the surface height E- 1  of the printing plate  12  is relatively lower than the surface height A- 1  of the printing plate  12 , which is the highest surface height of the various surface heights. The surface height of the printing plate  12  can be defined as the distance from the printing plate stage  10  to the top surface of the printing plate  12  not contacting the printing plate stage  10 . 
     The first through third regions  121  through  123  correspond to the first through third flatness profiles  131  through  133 , respectively. The pressure unit  100  may apply different pressures to the first through third regions  121  through  123  in order to improve the flatness profile of the printing plate  12 . Accordingly, the pressure unit  100  may include the plurality of pressure members  110  to correspond to the first through third regions  121  through  123 , respectively. For example, the pressure unit  100  may include a first pressure member  111  to apply pressure to the first region  121 , a second pressure member  112  to apply pressure to the second region  122 , and a third pressure member  113  to apply pressure to the third region  123  (see  FIG. 5 ). Each of the first through third pressure members  111  through  113  may be independently driven by a pressure member driver (not shown). Accordingly, the first through third pressure members  111  through  113  may apply different pressures to the first through third regions  121  through  123 , respectively, according to the flatness profiles of the first through third regions  121  through  123 , respectively. Pressure from the first through third pressure members  111  through  113  may be applied to the printing plate  12  in any suitable direction including, for example, a direction from the printing plate stage  10  to the printing plate  12 . 
     As noted above, the surface height A- 1  of the first region  121  of the printing plate  12  may be higher than the surface height B- 1  of the second region  122  of the printing plate  12  and the surface height B- 1  of the second region  122  of the printing plate  12  may be higher than the surface height C- 1  of the third region  123  of the printing plate  12 . After applying pressure through the pressure members  110 , the flatness of the printing plate  12  may improve. For example, in some cases, the flatness of the first region  121 , the second region  122 , and the third region  123  may be the same after having pressure applied. In some cases, the differences between the flatness of the first region  121 , the second region  122 , and the third region  123  may be reduced after having pressure applied. 
     In  FIG. 5 , reference characters A- 2  through E- 2  sequentially indicate magnitudes of pressure P applied to the printing plate  12  by the pressure members  110 . The magnitude of pressure P applied to the printing plate  12  may increase in the order of E- 2  to A- 2 . For example, the magnitude E- 2  of the pressure P applied to the printing plate  12  may be the smallest, whereas the magnitude A- 2  of the pressure P may be greatest. 
     Referring to  FIG. 4  and  FIG. 5 , since the surface height of the first region  121  is the highest, the magnitude E- 2  of the pressure P applied to the first region  121  by the first pressure member  111  may be the smallest relative to the magnitudes (e.g., A- 2  to D- 2 ) of the applied pressure P. In addition, since the surface height of the second region  122  is relatively lower than the surface height of the first region  121 , the magnitude D- 2  of the pressure P applied to the second region  122  by the second pressure member  112  may be relatively greater than the magnitude E- 2  of the pressure P applied to the first region  121 . Furthermore, since the surface height of the third region  123  is relatively lower than the surface height of the second region  122 , the magnitude A- 2  of the pressure P applied to the third region  123  by the third pressure member  113  may be relatively greater than the magnitude D- 2  of the pressure P applied to the second region  122 . As illustrated by  FIG. 4  and  FIG. 5 , a greater pressure may be applied to regions having a lower surface height. Similarly, a smaller pressure may be applied to regions having a higher surface height. 
     While the first through third regions  121  through  123  have been described as exemplary regions of the printing plate  12 , the printing plate  12  may include a plurality of regions as shown in  FIG. 4  and  FIG. 5 . In addition, the pressure unit  100  may include the plurality of pressure members  110 . Therefore, the pressure members  110  of the pressure unit  100  may also apply pressure to regions of the printing plate  12  other than the above-described first through third regions  121  through  123 . Accordingly, the flatness of the entire surface of the printing plate  12  can be improved. Consequently, the printing plate  12  having the improved flatness enables the pattern transfer device  1  to precisely transfer patterns onto the substrate  22 . 
     A pattern transfer method according to exemplary embodiments of the present invention will now be described with reference to  FIG. 1 ,  FIG. 4 ,  FIG. 5 ,  FIG. 6 ,  FIG. 7 ,  FIG. 8 ,  FIG. 9 ,  FIG. 10 ,  FIG. 11 ,  FIG. 12 , and  FIG. 13 . 
       FIG. 6  is a flowchart illustrating a pattern transfer method according to exemplary embodiments of the present invention.  FIG. 7  and  FIG. 8  are diagrams illustrating flatness measuring devices  301  and  302 , which measure the flatness of a printing plate  12 .  FIG. 9 ,  FIG. 10 ,  FIG. 11 ,  FIG. 12 , and  FIG. 13  are diagrams illustrating the process of transferring patterns formed on the printing plate  12  to a substrate  22 . 
     Referring to  FIG. 1 ,  FIG. 3 , and  FIG. 6 , the printing plate  12  on which predetermined patterns  14  are formed may be loaded on a printing plate stage  10  (S 1010 ). The printing plate  12  may be loaded on the printing plate stage  10  to overlap a pressure unit  100 , which is configured with the printing plate stage  10 . 
     Next, a flatness of the printing plate  12  loaded on the printing plate stage  10  may be measured (S 1020 ). Accordingly, the flatness profiles of the printing plate  12  are defined, and a plurality of regions  120  may be defined in the printing plate  12  to correspond respectively to a plurality of pressure members  110  of the pressure unit  100 . 
       FIG. 7  illustrates one example of a flatness measuring device. Referring to  FIG. 7 , the flatness of the printing plate  12  may be measured by the flatness measuring device  301 . The flatness measuring device  301  may include a blanket roll  310 , a blanket carriage  320 , a probe  331 , and a probe support  340  which fixes the probe  331  to the blanket carriage  320 . When the blanket roll  310  moves in a first direction M 1 , the flatness measuring device  301  may measure the flatness of the printing plate  12  by using the probe  331  installed on the blanket carriage  320 . To measure the flatness of the printing plate  12 , the probe  331  may contact a surface  1013  of the printing plate  12  and obtain a measurement of the flatness of surface  1013 . The flatness measuring device  301  may then calculate a difference in height between an ideal surface  1011  of the printing plate  12  for pattern formation and surface  1013  of the printing plate  12  loaded on the printing plate stage  10 , and may determine the flatness profiles of the printing plate  12  based on the calculated difference. 
       FIG. 8  illustrates another example of a flatness measuring device. The flatness measuring device  302 , illustrated in  FIG. 8 , may measure the flatness of the printing plate  12  by using a laser sensor  332 , instead of the probe  331 . For example, the flatness measuring device  302  may emit a laser beam using the laser sensor  332 , and may measure the time taken for the emitted laser beam to return after contacting each region of the surface  1013  of the printing plate  12 . The measured time may vary according to surface characteristics of the printing plate  12 . For example, a measured time for a laser beam emitted towards a region of the surface  1013  of the printing plate  12  that is relatively close to the laser sensor  332  is shorter than a measured time for a laser beam emitted towards a region of the surface  1013  of the printing plate  12  that is relatively far from the laser sensor  332 . Based on measured data, the flatness measuring device  302  may determine the flatness profiles of the printing plate  12  loaded on the printing plate stage  10 . In general, various types of laser beams and/or detectors may be used to determine the flatness of the printing plate  12 . 
     Once the flatness profiles of the printing plate  12  are determined, the surface  1013  of the printing plate  12  may be divided into a plurality of regions, so that pressure can be applied locally to the printing plate  12  by the pressure members  110  of the pressure unit  100 . 
     Next, the flatness of the printing plate  12  may be corrected based on the determined flatness profiles (S  1030 ). A method of correcting the flatness of the printing plate  12  may be the same as described above, and thus a redundant description thereof is omitted. 
     Referring to  FIG. 9 ,  FIG. 10 ,  FIG. 11 ,  FIG. 12 , and  FIG. 13 , the patterns  14  formed on the printing plate  12  having the corrected flatness may be transferred to the substrate  22  (S 1040 ). 
     Referring to  FIG. 9 , an ink supply unit  31  may be driven to apply a predetermined amount of ink I to a top surface of the printing plate  12 . The amount of ink I applied by the ink supply unit  40  may be more than enough to cover the entire top surface of the printing plate  12 . In general, any suitable amount of ink I may be applied to the top surface of the printing plate  12 . Ink I may be applied on any location of the printing plate  12 , including, for example, an end of the printing plate  12 . When ink I is applied to a position in the middle of the printing plate  12 , the number of horizontal movements of an ink-filling blade  32  may increase, thereby increasing processing time. 
     Referring to  FIG. 10 , ink I supplied to the top surface of the printing plate  12  may be evenly spread over the entire top surface of the printing plate  12  by the ink-filling blade  32 , so that each pattern  14  formed on the top surface of the printing plate  12  can be completely filled with ink I. The ink-filling blade  32 , which is separated from the printing plate  12  by a predetermined gap, may spread the ink I over the entire top surface of the printing plate  12  by pushing the ink I in any suitable direction, including, for example, a downward direction and/or a horizontal direction. 
     Referring to  FIG. 11 , ink I remaining on the top surface of the printing plate  12  after filling the pattern grooves  14  may be removed using a remaining ink-removing blade  33 . Ink I that fills the pattern grooves  14  may form patterns on the substrate  22  after a transfer process and a printing process is completed. However, ink I remaining in regions other than the pattern grooves may be printed on the substrate  22  by a transfer roll  34  to form unwanted patterns. For this reason, the remaining ink I must be completely removed. 
     Referring to  FIG. 12 , the transfer roll  34  may rotate when in contact with the top surface of the printing plate  12 , which may be completely or partially filled with ink I. Accordingly, a transfer process is performed. For example, ink I that fills the patterns  14  on the top surface of the printing plate  12  may be transferred to a surface of a blanket  34 b. The patterns  14  formed on the printing plate  12  should be transferred to the blanket  34   b  with no change in the size of the patterns  14  and the gap between the patterns  14 . Therefore, the rotation speed and horizontal movement speed of the transfer roll  34  must be controlled with great precision. 
     Referring to  FIG. 13 , after traversing the predetermined distance between the printing plate  12  and the substrate  22 , the transfer roll  34  may contact a top surface of the substrate  22  to print ink I, which has been transferred to the transfer roll  34 , on the top surface of the substrate  22 . In some cases, since the flatness of the printing plate  12  is corrected to be uniform across the entire surface of the printing plate  12 , the transfer process can be performed in a stable and precise manner. 
     A pattern transfer method according to exemplary embodiments of the present invention will now be described with reference to  FIG. 14 ,  FIG. 15 ,  FIG. 16 , and  FIG. 17 . 
       FIG. 14  is a cross-sectional view of a pattern transfer device  2  according to exemplary embodiments of the present invention.  FIG. 15  is a diagram illustrating a printing plate stage  20  and a pressure unit  200 .  FIG. 16  is a diagram illustrating the relationship between the pressure unit  200  and the flatness profiles and regions of a substrate  22 .  FIG. 17  is a diagram illustrating the operation of the pressure unit  200 . Elements having the same functions as those described with reference to  FIG. 1 ,  FIG. 2 ,  FIG. 3 ,  FIG. 4 ,  FIG. 5 ,  FIG. 6 ,  FIG. 7 ,  FIG. 8 ,  FIG. 9 ,  FIG. 10 ,  FIG. 11 ,  FIG. 12 , and  FIG. 13  are indicated by like reference numerals, and thus their description will be omitted. 
     Referring to  FIG. 14 , the pattern transfer device  2  may include a printing plate stage  10 , the substrate stage  20 , the pressure unit  200 , and a printing unit  30 . 
     Referring to  FIG. 14 ,  FIG. 15 ,  FIG. 16 , and  FIG. 17 , the pressure unit  200  may include a plurality of pressure members  210  to locally apply pressure to the substrate  22 . To apply pressure to the substrate  22 , the pressure unit  200  may be installed with the substrate stage  20  on which the substrate  22  is loaded. 
     The substrate  22  may be loaded on the substrate stage  20  to overlap the pressure unit  200 . The pressure members  210  of the pressure unit  200  may be driven in any suitable direction, including, for example, a direction from a top surface of the substrate stage  20 , on which the substrate  22  is placed, to the substrate  22 , so that the pressure members  210  can deliver pressure to the substrate  22 . The pressure members  110  may be, for example, pressure bars or pressure pins. 
     While the substrate  22  may be plate-shaped, the substrate  22  may not always have uniform flatness across its entire surface due to a variety of reasons. For example, the surface of the substrate  22  may be partially bent or curved when the substrate  22  is formed, or different external forces may be applied locally to the surface of the substrate  22  when the substrate  22  is loaded on the printing plate stage  10 . 
     Referring to  FIG. 16 , the substrate  22  may have a plurality of flatness profiles for the above-mentioned reasons. In addition, a plurality of regions may be defined in the substrate  22  to correspond to the flatness profiles, respectively. The number of the regions of the substrate  22  may correspond to the number of the pressure members  210  of the pressure unit  200 , so that a different pressure may be applied to each region of the substrate  22  according to the flatness of each region. 
     In  FIG. 16 , reference numeral  231  indicates a first flatness profile, reference numeral  232  indicates a second flatness profile, and reference numeral  233  indicates a third flatness profile. In addition, reference numeral  221  indicates a first region having the first flatness profile  231 , reference numeral  222  indicates a second region having the second flatness profile  232 , and reference numeral  223  indicates a third region having the third flatness profile  233 . 
     Reference characters A- 1  through E- 1  in  FIG. 16  indicate the difference in surface height according to the flatness profile of the substrate  22 . The surface height of the substrate  22  increases in the order of E- 1  to A- 1 . For example, the surface height E- 1  of the substrate  22  is relatively lower than the surface height A- 1  of the substrate  22 , which is the highest surface height of the various surface heights. The surface height of the substrate  22  can be defined as the distance from the substrate stage  20  to the top surface of the substrate  22  not contacting the substrate stage  20 . 
     The first through third regions  221  through  223  correspond to the first through third flatness profiles  231  through  233 , respectively. The pressure unit  200  may apply different pressures to the first through third regions  221  through  223  in order to improve the flatness profile of the substrate  22 . Accordingly, the pressure unit  200  may include the plurality of pressure members  210  to correspond to the first through third regions  221  through  223 , respectively. For example, the pressure unit  200  may include a first pressure member  211  to apply pressure to the first region  221 , a second pressure member  212  to apply pressure to the second region  222 , and a third pressure member  213  to apply pressure to the third region  223  (see  FIG. 17 ). Each of the first through third pressure members  211  through  213  may be independently driven by a pressure member driver (not shown). Accordingly, the first through third pressure members  211  through  213  may apply different pressures to the first through third regions  221  through  223 , respectively, according to the flatness profiles of the first through third regions  221  through  223 , respectively. Pressure from the first through third pressure members  211  through  213  may be applied to the substrate  22  in any suitable direction including, for example, a direction from the substrate stage  20  to the substrate  22 . 
     For example, as noted above, the surface height A- 1  of the first region  221  of the substrate  22  may be higher than the surface height B- 1  of the second region  222  of the substrate  22  and the surface height B- 1  of the second region  222  of the substrate  22  may be higher than the surface height C- 1  of the third region  223  of the substrate  22 . After applying pressure through the pressure members  210 , the flatness of the substrate  22  may improve. For example, in some cases, the flatness of the first region  221 , the second region  222 , and the third region  223  may be the same after having pressure applied. In some cases, the differences between the flatness of the first region  121 , the second region  122 , and the third region  223  may be reduced after having pressure applied. 
     In  FIG. 17 , reference characters A- 2  through E- 2  sequentially indicate magnitudes of pressure P applied to the substrate  22  by the pressure members  210 . The magnitude of pressure P applied to the substrate  22  may increase in the order of E- 2  to A- 2 . For example, the magnitude E- 2  of the pressure P applied to the substrate  22  may be the smallest, whereas the magnitude A- 2  of the pressure P may be the greatest. 
     Referring to  FIG. 16  and  FIG. 17 , since the surface height of the first region  221  is the highest, the magnitude E- 2  of the pressure P applied to the first region  221  by the first pressure member  211  may be smallest relative to the magnitudes (e.g., A- 2  to D- 2 ) of the applied pressure P. In addition, since the surface height of the second region  222  is relatively lower than the surface height of the first region  221 , the magnitude D- 2  of the pressure P applied to the second region  222  by the second pressure member  212  may be relatively greater than the magnitude E- 2  of the pressure P applied to the first region  221 . Furthermore, since the surface height of the third region  223  is relatively lower than the surface height of the second region  222 , the magnitude A- 2  of the pressure P applied to the third region  223  by the third pressure member  213  may be relatively greater than the magnitude D- 2  of the pressure P applied to the second region  222 . As illustrated by  FIG. 16  and  FIG. 17 , a greater pressure may be applied to regions having a lower surface height. Similarly, a smaller pressure may be applied to regions having a higher surface height. 
     While the first through third regions  221  through  223  have been described as exemplary regions of the substrate  22 , the substrate  22  may include a plurality of regions as shown in  FIGS. 16 and 17 . In addition, the pressure unit  200  may include the plurality of pressure members  210 . Therefore, the pressure members  210  of the pressure unit  200  may also apply pressure to regions of the substrate  22  other than the above-described first through third regions  221  through  223 . Accordingly, the flatness of the entire surface of the substrate  22  can be improved. Consequently, the substrate  22  having the improved flatness enables the pattern transfer device  2  to precisely transfer patterns onto the substrate  22 . 
     It will be apparent to those skilled in the art that various modifications and variations can be made in 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.