Patent Publication Number: US-2011069294-A1

Title: Apparatus and method for exposing edge of substrate

Description:
FIELD OF THE INVENTION 
     The present patent document is a divisional of U.S. patent application Ser. No. 11/455,433, filed Jun. 19, 2006, which claims priority to Korean Patent Application No. P2005-0133112 filed in Korea on Dec. 29, 2005, which are hereby incorporated by reference. 
    
    
     BACKGROUND OF THE INVENTION 
     The present invention relates to an apparatus and method for exposing an edge of a substrate to manufacture a flat display device, and more particularly, to an apparatus and method for exposing an edge of a substrate, in which an exposure time period for exposing the edge of the substrate is reduced. 
     Generally, a photolithography process is used to pattern a substrate in a process of manufacturing a semiconductor device or a flat display device. 
     The photolithography process includes a deposition process of depositing a photoresist on a substrate, an exposure process of exposing the photoresist deposited on the substrate, and a development process of developing the exposed substrate. 
     The exposure process is to selectively expose the photoresist deposited on the substrate using a mask. 
     Meanwhile, a process defect occurs due to foreign materials generated by peeling at the edge of the substrate during movement, exposure or development of the substrate. To prevent such peeling at the edge of the substrate, an edge exposure process is performed before the exposure process to remove the edge of the substrate at a certain width. 
       FIG. 1  is a block diagram illustrating a related art apparatus for exposing an edge of a substrate. 
     Referring to  FIG. 1 , the related art apparatus for exposing an edge of a substrate includes a loading/unloading unit  10  loading and unloading the substrate, and an edge exposure unit  20  exposing the edge of the substrate loaded by the loading/unloading unit  10 . 
     The loading/unloading unit  10  loads the substrate externally deposited with a photoresist into the edge exposure unit  20  using a robot arm. Also, the loading/unloading unit  10  unloads the substrate exposed by the edge exposure unit  20  from the edge exposure unit  20  using the robot arm. 
     The edge exposure unit  20  exposes the edge, i.e., long and short sides, of the substrate loaded by the loading/unloading unit  10  at a certain width. 
       FIG. 2  illustrates the related art edge exposure unit  20  shown in  FIG. 1 . 
     Referring to  FIG. 2  in connection with  FIG. 1 , the related art edge exposure unit  20  includes a stage  21  supporting the substrate deposited with the photoresist, a driving shaft  22  moving the stage  21  in a first direction (X axis) and rotating the stage  21 , a rail  23  guiding the driving shaft  22  to move the driving shaft  22  to the first direction, and an exposure unit provided in the rail  23  to expose the edge of the substrate. 
     The stage  21  includes a plurality of lift pins  25  supporting and fixing the substrate loaded from the loading/unloading unit  10 . The lift pins  25  are ascended and descended by a driving device (not shown) to adsorb the substrate under the vacuum state. 
     The driving shaft  22  is linked to the driving device to move the stage  21  in the first direction (X axis) along the rail  23 . Also, the driving shaft  22  is rotated by the driving device to rotate the stage  21 . 
     The rail  23  guides the driving shaft  22  to move the driving shaft  22  to the first direction (X axis). 
     The exposure unit includes a support bar  24  arranged to vertically cross the rail  23 , first and second optical systems  26   a  and  26   b  arranged in parallel at a side of the support bar  24 , and a distance controller  28  controlling the distance between the first and second optical systems  26   a  and  26   b.    
     The support bar  24  is fixed to the rail  23  to vertically cross the rail  23 . 
     Each of the first and second optical systems  26   a  and  26   b  are spaced apart from each other to correspond to the distance between the long sides or the short sides of the substrate. Each of the first and second optical systems  26   a  and  26   b  irradiates light toward the long sides or the short sides of the substrate to expose the edge of the substrate. 
     The distance controller  28  controls the distance between the first and second optical systems  26   a  and  26   b  to correspond to the distance between the long sides or the short sides of the substrate. 
       FIGS. 3A to 3G  are sectional views illustrating exposure process steps of exposing the edge of the substrate using the related art edge exposure unit  20 . 
     The exposure process steps of exposing the edge of the substrate according to the related art will be described as follows. 
     First, as shown in  FIG. 3A , the substrate  2  deposited with the photoresist is loaded, as shown by arrow  30 , onto the stage  21  of the home position by the robot arm of the loading/unloading unit  10 . If the robot arm of the loading/unloading unit  10  on which the substrate is mounted is positioned on the stage  21 , the lift pins  25  are ascended by the driving device to lift the substrate  2  mounted on the robot arm. If the substrate  2  is lifted at a certain height by the lift pins  25 , the robot arm returns to the loading/unloading unit  10 . At this time, the distance between the first and second optical systems  26   a  and  26   b  is set by the distance controller  28  to correspond to the distance between the long sides of the substrate  2 . 
     When the robot arm is taken out from the stage  21 , the lift pins  25  descend and are fixed to the surface of the stage  21  as shown in  FIG. 3B . 
     Subsequently, as shown in  FIG. 3C , the driving shaft  22  moves to the first direction (X axis) along the rail  23  so that the stage  21  moves, as shown by arrow  31 , to the exposure unit. When the substrate  2  moves near the exposure unit, the first and second optical systems  26   a  and  26   b  irradiate light toward both edges  29   a  of the long sides of the substrate  2  to expose the long sides of the substrate  2 . At this time, the first and second optical systems  26   a  and  26   b  may be driven by a sensing signal of a sensor (not shown) that senses the position of the substrate  2 . 
     Subsequently, as shown in  FIG. 3D , when the long sides of the substrate  2  are completely exposed, the driving shaft  22  is clockwise rotated, as shown by arrow  32 , at an angle of 90° as shown in  FIG. 3D . At this time, the distance between the first and second optical systems  26   a  and  26   b  is set, as shown by arrow  33 , by the distance controller  28  to correspond to the distance between the short sides of the substrate  2 . 
     Next, as shown in  FIG. 3E , when the substrate  2  is completely rotated, the driving shaft  22  moves to the first direction (X axis) along the rail  23  so that the stage  21  moves to the home position. If the substrate  2 , which is moving to the home position, moves near the exposure unit, the first and second optical systems  26   a  and  26   b  irradiate light toward both edges  29   b  of the short sides of the substrate  2  to expose the short sides of the substrate  2 . 
     Subsequently, as shown in  FIG. 3F , when the short sides of the substrate  2  are completely exposed, the driving shaft  22  is clockwise rotated, as shown by arrow  34 , at an angle of 90° as shown in  FIG. 3G . At this time, the distance between the first and second optical systems  26   a  and  26   b  is set by the distance controller  28  to correspond to the distance between the long sides of the substrate  2 . 
     Then, when rotation of the substrate  2  is completed, the substrate  2  whose long and short sides have completely been exposed is ascended at a certain height by the lift pins  25 . The robot arm of the loading/unloading unit  10  is inserted between the ascended substrate  2  and the stage  21 . Subsequently, the lift pins  25  are descended into the stage  21  so that the substrate  2  is mounted on the robot arm and thus unloaded from the loading/unloading unit  10 . 
     Consequently, in the related art apparatus and method for exposing the edge of the substrate, as shown in  FIGS. 3A to 3G , the edge of the substrate  2  is exposed in the order of loading of the substrate  2 , movement of the stage  21  and exposure of the long sides, rotation of the stage  21 , movement of the stage  21  and exposure of the short sides, rotation of the stage  21 , and unloading of the substrate  2 . 
     However, the related art apparatus and method for exposing the edge of the substrate have several problems. 
     Since both a reciprocating movement time period of the stage  21  to the first direction (X axis) and a rotational time period of the stage  21  are required, the process time of exposing the edge of the substrate  2  increases. 
     Further, since the substrate  2  is unloaded through a port after being loaded into the port, the process time of exposing the edge of the substrate  2  increases due to a standby time period of the substrate  2 . 
     Moreover, since the stage  21  should be rotated, the size of the apparatus increases. 
     SUMMARY OF THE INVENTION 
     The present invention is directed to an apparatus and method for exposing an edge of a substrate, which substantially obviate one or more problems due to limitations and disadvantages of the related art. 
     An objective of the present invention is to provide an apparatus and method for exposing an edge of a substrate, in which an exposure time period for exposing the edge of the substrate is reduced. 
     Additional advantages, objectives, and features of the invention in part will be set forth in the description which follows and in part will become apparent to those having ordinary skill in the art upon examination of the following or may be learned from practice of the invention. The objectives and other advantages of the invention may be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings. 
     In one embodiment, an apparatus is provided for exposing an edge of a substrate. The apparatus comprises a loading unit loading the substrate, and an edge exposure unit exposing the edge of the substrate loaded by the loading unit using each of a long side exposure unit and a short side exposure unit. 
     In another aspect of the present invention, a method for exposing an edge of a substrate includes mounting the substrate on a stage, and then exposing the edge of the substrate mounted on the stage using each of a long side exposure unit and a short side exposure unit. 
     In other aspect of the present invention, a method for exposing an edge of a substrate includes mounting the substrate on a stage, exposing both edges of a first side of the substrate in a state that the stage is stopped, exposing both edges of a second side of the substrate while moving the stage, and drawing the substrate of which both edges of the first and second sides have been exposed, from the stage and moving the drawn substrate to the outside. 
    
    
     
       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 application, illustrate embodiment(s) of the invention and together with the description serve to explain the principle of the invention. In the drawings: 
         FIG. 1  is a block diagram illustrating a related art apparatus for exposing an edge of a substrate; 
         FIG. 2  illustrates a related art edge exposure unit shown in  FIG. 1 ; 
         FIGS. 3A to 3G  are sectional views illustrating exposure process steps of exposing an edge of a substrate using a related art edge exposure unit; 
         FIG. 4  is a block diagram illustrating an apparatus for exposing an edge of a substrate in accordance with the first embodiment of the present invention; 
         FIGS. 5A and 5B  are sectional views illustrating an edge exposure unit shown in  FIG. 4 ; 
         FIG. 6  illustrates a conveyer unit shown in  FIG. 4 ; 
         FIGS. 7A to 7J  are sectional views illustrating exposure process steps of exposing an edge of a substrate in accordance with the first embodiment of the present invention; 
         FIG. 8  is a block diagram illustrating an apparatus for exposing an edge of a substrate in accordance with the second embodiment of the present invention; 
         FIG. 9  is a sectional view illustrating an edge exposure unit shown in  FIG. 8 ; 
       and 
         FIGS. 10A to 10G  are sectional views illustrating exposure process steps of exposing an edge of a substrate in accordance with the second embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Reference will now be made in detail to the preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings. Wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or like parts. 
       FIG. 4  is a block diagram illustrating an apparatus for exposing an edge of a substrate in accordance with the first embodiment of the present invention. 
     Referring to  FIG. 4 , the apparatus for exposing an edge of a substrate according to the first embodiment of the present invention includes a loading unit  110  loading the substrate, an edge exposure unit  120  exposing the edge of the substrate loaded by the loading unit  110 , and a conveyer unit  125  moving the substrate whose edge has been exposed by the edge exposure unit  120 . 
     The substrate may be a wafer for manufacture of a semiconductor device or a glass for manufacture of an image display device. 
     The loading unit  110  loads the substrate externally deposited with photoresist into the edge exposure unit  120  using a robot arm. 
     The edge exposure unit  120  fixes the substrate loaded by the loading unit  110  and exposes long sides of the fixed substrate at a certain width using a long side exposure unit. Then, the edge exposure unit  120  exposes short sides of the exposed substrate at a certain width using a short side exposure unit. 
     The conveyer unit  125  moves the substrate whose edge has been exposed by the edge exposure unit  120  using a conveyer. 
     The apparatus for exposing the edge of the substrate in accordance with the first embodiment of the present invention can reduce an edge exposure process time period by arranging the loading unit  110 , the edge exposure unit  120  and the conveyer unit  125  in an in-line type. 
       FIGS. 5A and 5B  illustrate the edge exposure unit  120  shown in  FIG. 4 . 
     Referring to  FIGS. 5A and 5B  in connection with  FIG. 4 , the edge exposure unit  120  according to the first embodiment of the present invention includes a stage  221  supporting the substrate  202  loaded from the loading unit  110 , a driving shaft  222  moving the stage  221  in a first direction (X axis), a rail  223  guiding the driving shaft  222  to move the driving shaft  222  to the first direction, a long side exposure unit exposing the long sides of the substrate  202  supported by the stage  221 , and a short side exposure unit exposing the short sides of the substrate  202  moved by movement of the stage  221 . 
     The stage  221  includes a plurality of lift pins  225  supporting and fixing the substrate  202  loaded from the loading unit  110 . The lift pins  225  are ascended and descended by a driving device (not shown) to adsorb the substrate  202  under the vacuum state. The substrate  202  from the loading unit  110  is loaded onto the stage  221  through a port  215  provided to face one side of the stage  221 . 
     The driving shaft  222  is linked to the driving device to move the stage  221  in the first direction (X axis) along the rail  223 . 
     The rail  223  is provided on a support  200  and guides the driving shaft  222  to move the driving shaft  222  to the first direction (X axis). 
     The long side exposure unit includes first and second driving bars  230  and  232  arranged on the stage  221  to face each other, a moving bar  234  arranged between the first and second driving bars  230  and  232  to move to a second direction (Y axis), and first and second optical systems  226   a  and  226   b  arranged at a side of the moving bar  234  to correspond to the distance between the long sides of the substrate  202 . 
     The first and second driving bars  230  and  232  are arranged on the stage  221  to vertically cross the rail  223  and move the moving bar  234  to the second direction (Y axis). At this time, the first driving bar  230  is arranged near the port  215  to which the substrate  202  is loaded by the loading unit  110  while the second driving bar  232  is arranged near the short side exposure unit. 
     The moving bar  234  is arranged to vertically cross the first and second driving bars  230  and  232  and faces the stage  221 . The moving bar  234  is linked to driving of the first and second driving bars  230  and  232  to move to the second direction (Y axis). The moving bar  234  may be any one of LM (Linear Motion) rail and LM block of LM guide. Each of the first and second driving bars  230  and  232  may be the other one of LM rail and LM block of LM guide. 
     The first and second optical systems  226   a  and  226   b  are arranged in parallel at a side of the moving bar  234  and spaced apart from each other to correspond to the distance between the long sides of the substrate  202 . Each of the first and second optical systems  226   a  and  226   b  irradiates light toward the long sides of the substrate  202  moved by the moving bar  234  and mounted on the stage  221 . To this end, each of the first and second optical systems  226   a  and  226   b  may be laser modules irradiating laser or projection optical modules irradiating ultraviolet rays. 
     Meanwhile, the long side exposure unit may further include a distance controller  228   a  that controls the distance between the first and second optical systems  226   a  and  226   b  in accordance with the size of the substrate  202 . 
     The short side exposure unit includes a support bar  240  arranged in parallel with the long side exposure unit, and third and fourth optical systems  246   a  and  246   b  arranged at a side of the support bar  240  to correspond to the distance between the short sides of the substrate  202 . 
     The support bar  240  is arranged in parallel with the second driving bar  232  of the long side exposure unit to vertically cross the rail  223 . 
     The third and fourth optical systems  246   a  and  246   b  are arranged in parallel at a side of the support bar  240  and spaced apart from each other to correspond to the distance between the short sides of the substrate  202 . Each of the third and fourth optical systems  246   a  and  246   b  irradiates light toward the short sides of the substrate  202  mounted on the stage  221  moved to the first direction (X axis) along the rail  223 . To this end, each of the third and fourth optical systems  246   a  and  246   b  may be laser modules irradiating laser or projection optical modules irradiating ultraviolet rays. 
     Meanwhile, the short side exposure unit may further include a distance controller  228   b  that controls the distance between the third and fourth optical systems  246   a  and  246   b  in accordance with the size of the substrate  202 . 
       FIG. 6  illustrates the conveyer unit  125  shown in  FIG. 4 . 
     Referring to  FIG. 6  in connection with  FIG. 4 , the conveyer unit  125  includes a substrate drawing unit  250  drawing the substrate, whose edge has been exposed, from the edge exposure unit  120 , and a substrate moving unit  270  moving the substrate drawn by the substrate drawing unit  250  to an external development unit (not shown). 
     The substrate drawing unit  250  includes at least one cylinder  252  arranged at an end of the support  220 , a driving shaft  254  vertically driven by driving of the cylinder  252 , a frame  256  arranged at an end of the driving shaft  254 , and a roller driver arranged in parallel with the frame  256  to draw the substrate from the stage  221  of the edge exposure unit  120 . 
     Each of the cylinders  252  is driven by a driving device (not shown) to ascend and descend the driving shaft  254 . 
     The driving shaft  254  is linked to driving of the cylinder  252  to ascend and descend the frame  256 . 
     The roller driver includes a plurality of guide wings  260  arranged in parallel at constant intervals, and a plurality of rollers  262  arranged in the respective guide wings  260  in parallel at constant intervals. 
     The guide wings  260  are arranged in parallel to be inserted between the stage  221  and the substrate. In other words, each of the guide wings  260  is inserted into a space between the lift pins ascended from the stage  221  at a certain height. 
     The rollers  262  are rotated by a driving motor (not shown) to move the substrate to the substrate moving unit  270 . At this time, when the lift pins arranged in the stage  221  are ascended into the stage  221 , the substrate is mounted on the rollers  262 . Otherwise, when the driving shaft  254  is ascended by driving of the cylinder  252 , the substrate is mounted on the rollers  262 . 
     The substrate moving unit  270  is arranged near the substrate drawing unit  250  and includes a plurality of rollers  272  that moves the substrate moved by the roller driver to the external development unit. The substrate moving unit  270  may be a conveyer arranged in the external development unit to move the substrate during development. 
       FIGS. 7A to 7J  are sectional views illustrating exposure process steps of exposing the edge of the substrate using the edge exposure unit according to the first embodiment of the present invention. 
     The exposure process steps of exposing the edge of the substrate using the edge exposure unit according to the first embodiment of the present invention will be described as follows. 
     First, when the substrate is loaded onto the stage  221  of the edge exposure unit  120  through the port (not shown) by the robot arm of the loading unit  110 , as shown in  FIG. 7A , the lift pins  225  arranged in the stage  221  are ascended to lift the substrate  202  mounted on the robot arm. When the substrate  202  is lifted by the lift pins  225 , the robot arm returns to the loading unit  110 . 
     When the robot arm is taken out from the stage  221 , as shown in  FIG. 7B , the lift pins  225  descend so that the substrate  202  is mounted on the stage  221  and then aligned. 
     Subsequently, the moving bar  234  is slowly moved to the second direction (Y axis) by means of driving of the first and second driving units  230  and  232  and the moving bar  234 . When the moving bar  234  moves near the substrate  202 , the first and second optical systems  226   a  and  226   b  irradiate, as shown by arrow  280 , light toward both edges of the long sides of the substrate  202  to expose the long sides of the substrate  202 . At this time, the first and second optical systems  226   a  and  226   b  may be driven by a sensing signal from a sensor (not shown) that senses the position of the substrate  202 . 
     Subsequently, when the long sides of the substrate  202  are completely exposed, the stage  221  is slowly moved, as shown by arrow  290 , to the first direction (X axis), i.e., toward the conveyer unit  125  by driving of the driving shaft  222 . 
     Next, when the substrate  202  mounted on the stage  221  moves near the short side exposure unit, as shown in  FIGS. 7C and 7D , the third and fourth optical systems  246   a  and  246   b  irradiate, as shown by arrow  282 , light toward both edges of the short sides of the substrate  202  mounted on the stage  221 , which is moving along the rail  223 , as shown by arrows  290  and  291 , so as to expose the short sides of the substrate  202 . At this time, the third and fourth optical systems  246   a  and  246   b  may be driven by a sensing signal from a sensor (not shown) that senses the position of the substrate  202 . 
     Subsequently, when the short sides of the substrate  202  are completely exposed, as shown in  FIG. 7E , the stage  221  continues to move, as shown by arrow  292 , to the conveyer unit  125  along the rail  223 . At this time, the lift pins  225  ascend before the stage  221  is near the guides  260  of the substrate drawing unit. Thus, the substrate  202  mounted on the stage  221  ascends at a certain height. 
     When the stage  221  is moved, as shown by arrow  293 , to the drawing position of the substrate, as shown in  FIG. 7F , the guide wings  260  are inserted into the space between the stage  221  and the substrate  202 . 
     Next, as shown in  FIG. 7G , as the lift pins  225  are descended into the stage  221 , the substrate  202  supported by the lift pins  225  is mounted on the rollers  262  arranged in the guide wings  260 . At the same time, the cylinder  252  is driven so that the guide wings  260  ascend at a certain height. In this case, the substrate  202  supported by the lift pins  225  may be mounted on the rollers  262  arranged in the guide wings  260 . 
     Subsequently, as shown in  FIG. 7H , to move the substrate  202  to the external development unit, the driving shaft  254  is linked to driving of the cylinder  252  and ascends, so that the guide wings  260  ascend. At this time, the guide wings  260  ascend, as shown by arrow  294 , to the position corresponding to the rollers  272  arranged in the substrate drawing unit  270 . At the same time, the stage  221  stopped at the drawing position of the substrate  202  is moved, as shown by arrow  295 , to the first direction (X axis), i.e., the port  215  along the rail  223  and returns to the home position. 
     Afterwards, when the rollers  262  arranged in the guide wings  260  and the rollers  272  arranged in the substrate drawing unit  270  are aligned, as shown in  FIG. 7I , the substrate  202  is moved to the external development unit as the rollers  262  and  272  rotate. 
     Then, when the substrate  202  is moved to the external development unit, as shown in  FIG. 7J , a new substrate  202  is loaded onto the stage  221 , which has returned to the home position, by the robot arm of the loading unit  110 . While the substrate  202  is being loaded onto the stage, the guide wings  260  is descended to the position for drawing the substrate  202  by driving of the cylinder  252  and is in a standby state. 
     In the aforementioned apparatus and method for exposing the edge of the substrate according to the first embodiment of the present invention, as shown in  FIGS. 7A to 7J , the edge of the substrate  202  is exposed in the order of loading of the substrate  202 , exposure of the long sides of the stopped substrate  202 , movement of the stage  221  and exposure of the short sides of the substrate  202  concurrently, and movement of the stage  221  and unloading of the substrate  202  concurrently. 
     Accordingly, in the aforementioned apparatus and method for exposing the edge of the substrate according to the first embodiment of the present invention, the substrate  202  is moved in an in-line type without any unnecessary standby time period of the substrate  202  such as rotation of the substrate  202  and reciprocating movement of the stage  221  to expose the edge of the substrate  202 , thereby reducing the edge exposure time period. Therefore, it is possible to improve productivity. Also, since no rotation of the substrate  202  is required, it is possible to reduce the size of the apparatus. 
     Meanwhile, the aforementioned apparatus and method for exposing the edge of the substrate according to the first embodiment of the present invention may depend on the position between the loading unit  110  and the edge exposure unit  120 . 
       FIG. 8  is a block diagram illustrating an apparatus for exposing an edge of a substrate in accordance with the second embodiment of the present invention. 
     Referring to  FIG. 8 , the apparatus for exposing an edge of a substrate according to the second embodiment of the present invention includes a loading unit  110  loading the substrate, an edge exposure unit  320  arranged below the loading unit  110  to expose the edge of the substrate loaded by the loading unit  110  using a short side exposure unit and a long side exposure unit, and a conveyer unit  125  moving the substrate whose edge has been exposed by the edge exposure unit  320 . 
     The apparatus for exposing the edge of the substrate in accordance with the second embodiment of the present invention can reduce an edge exposure process time period by arranging the edge exposure unit  320  and the conveyer unit  125  excluding the loading unit  110  in an in-line type. 
     Meanwhile, the apparatus for exposing an edge of a substrate in accordance with the second embodiment of the present invention has the same elements as those of the first embodiment excluding the edge exposure unit  320 . Therefore, description of other elements excluding the edge exposure unit  320  will be replaced with the description according to the first embodiment. 
       FIG. 9  illustrates the edge exposure unit  320  shown in  FIG. 8 . 
     Referring to  FIG. 9  in connection with  FIG. 8 , the edge exposure unit  320  according to the second embodiment of the present invention includes a stage  321  supporting the substrate  302  loaded from the loading unit  110 , a driving shaft (not shown) moving the stage  321  to a first direction (X axis), a rail  323  guiding the driving shaft to move the driving shaft to the first direction, a short side exposure unit exposing the short sides of the substrate  302  supported by the stage  321 , and a long side exposure unit exposing the long sides of the substrate  302  moved along the movement of the stage  321 . 
     The stage  321  includes a plurality of lift pins  325  supporting and fixing the substrate  302  loaded from the loading unit  110 . The lift pins  325  are ascended and descended by a driving device (not shown) to adsorb to the substrate  302  under the vacuum state. The substrate  302  from the loading unit  110  is loaded onto the stage  321  through a port  315  provided to face an upper end of the stage  321 . 
     The driving shaft is linked to the driving device to move the stage  321  in the first direction (X axis) along the rail  323 . 
     The rail  323  guides the driving shaft to move the driving shaft to the first direction (X axis). 
     The short side exposure unit includes first and second driving bars  330  and  332  arranged on the stage  321  to face each other, a moving bar  334  arranged between the first and second driving bars  330  and  332  to move to a second direction (Y axis), and first and second optical systems  326   a  and  326   b  arranged at a side of the moving bar  334  to correspond to the distance between the short sides of the substrate  302 . 
     The first and second driving bars  330  and  332  are arranged on the stage  321  to vertically cross the rail  323  and move the moving bar  334  to the second direction (Y axis). At this time, the first driving bar  330  is arranged to be vertical to the port  315  to which the substrate  302  is loaded by the loading unit  110 , while the second driving bar  332  is arranged near the short side exposure unit. 
     The moving bar  334  is arranged to vertically cross the first and second driving bars  330  and  332  and faces the stage  321 . The moving bar  334  is linked to driving of the first and second driving bars  330  and  332  to move to the second direction (Y axis). The moving bar  334  may be any one of LM rail and LM block of LM guide. Each of the first and second driving bars  330  and  332  may be other one of LM rail and LM block of LM guide. 
     The first and second optical systems  326   a  and  326   b  are arranged in parallel at a side of the moving bar  334  and spaced apart from each other to correspond to the distance between the short sides of the substrate  302 . Each of the first and second optical systems  326   a  and  326   b  irradiates light toward the short sides of the substrate  302  moved by the moving bar  334  and mounted on the stage  321 . To this end, each of the first and second optical systems  326   a  and  326   b  may be laser modules irradiating laser or projection optical modules irradiating ultraviolet rays. 
     Meanwhile, the short side exposure unit may further include a distance controller  328   a  that controls the distance between the first and second optical systems  326   a  and  326   b  in accordance with the size of the substrate  302 . 
     The long side exposure unit includes a support bar  340  arranged in parallel with the long side exposure unit, and third and fourth optical systems  346   a  and  346   b  arranged at each side of the support bar  340  to correspond to the distance between the long sides of the substrate  302 . 
     The support bar  340  is arranged in parallel with the second driving bar  332  of the short side exposure unit to vertically cross the rail  323 . 
     The third and fourth optical systems  346   a  and  346   b  are arranged in parallel at each side of the support bar  340  and spaced apart from each other to correspond to the distance between the long sides of the substrate  302 . Each of the third and fourth optical systems  346   a  and  346   b  irradiates light toward the long sides of the substrate  302  mounted on the stage  321  moved to the first direction (X axis) along the rail  323 . To this end, each of the third and fourth optical systems  346   a  and  346   b  may be laser modules irradiating laser or projection optical modules irradiating ultraviolet rays. 
     Meanwhile, the long side exposure unit may further include a distance controller  328   b  that controls the distance between the third and fourth optical systems  346   a  and  346   b  in accordance with the size of the substrate  302 . 
       FIGS. 10A to 10G  are sectional views illustrating exposure process steps of exposing the edge of the substrate using the edge exposure unit according to the second embodiment of the present invention. 
     The exposure process steps of exposing the edge of the substrate using the edge exposure unit according to the second embodiment of the present invention will be described as follows. 
     First, as shown in  FIG. 10A , the substrate  302  is loaded, as shown by arrow  390 , onto the stage  321  of the edge exposure unit  320  through the port  315  by the robot arm of the loading unit  110 . 
     As shown in  FIG. 10B , the lift pins  325  arranged in the stage  321  are ascended to lift the substrate  302  mounted on the robot arm. When the substrate  302  is lifted by the lift pins  325 , the robot arm returns to the loading unit  110 . 
     Subsequently, when the robot arm is taken out from the stage  321 , the lift pins  325  descend so that the substrate  302  is mounted on the stage  321  and then aligned. 
     Then, the moving bar  334  is slowly moved to the second direction (Y axis) by means of driving of the first and second driving bars  330  and  332  and the moving bar  334 . When the moving bar  334  moves near the substrate  302 , as shown in  FIG. 10C , the first and second optical systems  326   a  and  326   b  irradiate light toward both edges  329   a  of the short sides of the substrate  302  to expose the short sides of the substrate  302 . At this time, the first and second optical systems  326   a  and  326   b  may be driven by a sensing signal from a sensor (not shown) that senses the position of the substrate  302 . 
     Subsequently, as shown in  FIG. 10D , when the short sides of the substrate  302  are completely exposed, the stage  321  is slowly moved, as shown by arrow  391 , to the first direction (X axis), i.e., toward the conveyer unit  125  along the rail  323 . 
     Next, when the substrate  302  mounted on the stage  321  moves near the long side exposure unit, as shown in  FIG. 10E , the third and fourth optical systems  346   a  and  346   b  irradiate light toward both edges  329   b  of the long sides of the substrate  302  mounted on the stage  321 , which is moving along the rail  323 , as shown by arrow  391 , so as to expose the long sides of the substrate  302 . At this time, the third and fourth optical systems  346   a  and  346   b  may be driven by a sensing signal from a sensor (not shown) that senses the position of the substrate  302 . 
     Subsequently, when the long sides of the substrate  302  are completely exposed, the stage  321  continues to move to the conveyer unit  125  along the rail  323 . Thus, the stage  321  is moved to the drawing position of the substrate and then stopped. 
     Afterwards, as shown in  FIG. 10F , the substrate  302  mounted on the stage  321  stopped at the drawing position of the substrate is drawn from the stage  321  in accordance with the operation of the conveyer unit  125  shown in  FIGS. 7F to 7I  and then moved, as shown by arrow  392 , to the external development unit. The operation of the conveyer unit  125  will be replaced with the description of  FIGS. 7F to 7I . 
     While the substrate  302  drawn from the stage  321  by the operation of the conveyer unit  125  is moving to the external development unit, as shown in  FIG. 10G , the stage  321  is moved to the first direction (X axis), i.e., toward the port  325  along the rail  323  and returns to the home position. 
     In the aforementioned apparatus and method for exposing the edge of the substrate according to the second embodiment of the present invention, as shown in  FIGS. 10A to 10G , the edge of the substrate  302  is exposed in the order of loading of the substrate  302 , exposure of the short sides of the stopped substrate  302 , movement of the stage  321  and exposure of the long sides of the substrate  302  concurrently, and movement of the stage  321 , and unloading of the substrate  302 . 
     Accordingly, in the aforementioned apparatus and method for exposing the edge of the substrate according to the second embodiment of the present invention, the substrate  302  is moved in an in-line type without any unnecessary standby time period of the substrate  302  such as rotation of the substrate  302  and reciprocating movement of the stage  321  to expose the edge of the substrate  302 , thereby reducing the edge exposure time period. Therefore, it is possible to improve productivity. Also, since no rotation of the substrate  302  is required, it is possible to reduce the size of the apparatus. 
     As described above, the aforementioned apparatus and method for exposing the edge of the substrate according to the embodiments of the present invention have the following advantages. 
     Since the edge of the substrate is exposed using each of the long side exposure unit and the short side exposure unit, it is possible to reduce the edge exposure time period, thereby improving productivity. 
     In addition, since no rotation of the substrate is required, it is possible to reduce the size of the apparatus. Moreover, since the apparatus is provided in an in-line type, it is possible to easily draw the substrate using the conveyer. 
     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 inventions. Thus, it is intended that the present invention covers the modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents.