Abstract:
Provided are an exposure apparatus and an exposure method using the same. The exposure apparatus includes: a light source unit configured to emit light; a substrate stage supporting a substrate, the substrate comprising an exposure area and a non-exposure area; and a prism unit disposed between the light source unit and the substrate stage, the prism unit movable so as to transmit the light to the exposure area and to block the light from the non-exposure area.

Description:
This application claims priority from Korean Patent Application No. 10-2010-0069567 filed on Jul. 19, 2010 in the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference in its entirety. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates generally to flat panel displays. More specifically, the present invention relates to an exposure apparatus and an exposure method for fabricating flat panel displays. 
     2. Description of the Related Art 
     Large flat panel displays (FPDs), such as liquid crystal displays (LCDs) and plasma displays, are currently desirable due to the fact that they can support large screen sizes while remaining thin and relatively low-weight. The fabrication of an FPD panel often involves transferring mask patterns onto a substrate through a proximity exposure process. An exposure apparatus used in this exposure process may include a plurality of masks, each having a smaller size than that of the substrate that is to be exposed to light. In addition, the exposure apparatus may include a blocking unit which blocks light from reaching areas of the substrate that are not to be exposed to light. 
     When this exposure apparatus is used in an exposure process, the amount of light irradiated onto the substrate is often not constant due to the blocking unit. That is, different areas of the substrate receive differing amounts of light during an exposure process. Accordingly, stain defects can be generated in an exposure area of the substrate, resulting in a reduction in the quality of display panels manufactured using this exposure apparatus. 
     SUMMARY OF THE INVENTION 
     Aspects of the present invention provide an exposure apparatus generating fewer stain defects in an exposure area during an exposure process. 
     Aspects of the present invention also provide an exposure method which generates fewer stain defects in an exposure area during an exposure process. 
     However, the various aspects of the present invention are not restricted to the one set forth herein. The above and other aspects of the present invention will become more apparent to one of ordinary skill in the art to which the present invention pertains by referencing the detailed description of the present invention given below. 
     According to an aspect of the present invention, there is provided an exposure apparatus including: a light source unit configured to emit light; a substrate stage supporting a substrate, the substrate comprising an exposure area and a non-exposure area; and a prism unit disposed between the light source unit and the substrate stage, the prism unit movable so as to transmit the light to the exposure area and to block the light from the non-exposure area. 
     According to another aspect of the present invention, there is provided an exposure method including: providing a substrate comprising an exposure area and a non-exposure area; irradiating light onto the substrate; inputting the light to a prism unit; while overlapping the prism unit and the exposure area, moving the prism unit so as to transmit the light through the prism unit; and while overlapping the prism unit and the exposure area, moving the prism unit so as to block the light from the non-exposure area by substantially reflecting the light. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The above and other aspects and features of the present invention will become more apparent by describing in detail exemplary embodiments thereof with reference to the attached drawings, in which: 
         FIG. 1  is a side view of an exposure apparatus according to an exemplary embodiment of the present invention; 
         FIG. 2  is a top view of the exposure apparatus shown in  FIG. 1 ; 
         FIG. 3  is a diagram illustrating a prism unit included in the exposure apparatus of  FIG. 1 ; 
         FIGS. 4 and 5  are diagrams for explaining an exposure method that uses the exposure apparatus of  FIG. 1 ; 
         FIG. 6  is a diagram illustrating a case where the prism unit of the exposure apparatus of  FIG. 1  overlaps an exposure area of a substrate; 
         FIG. 7  is a diagram illustrating a case where the prism unit of the exposure apparatus of  FIG. 1  overlaps a non-exposure area of the substrate; and 
         FIGS. 8A through 11B  are diagrams for explaining another exposure method that uses the exposure apparatus of  FIG. 1 . 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Advantages and features 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 embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete and will fully convey the concept of the invention to those skilled in the art, and the present invention will only be defined by the appended claims. Like reference numerals 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 figures. It will be understood that the spatially relative terms are intended to encompass different orientations of the device in use or operation, in addition to the orientation depicted in the figures. Throughout the specification, like reference numerals in the drawings denote like elements. 
     Embodiments of the invention are described herein with reference to plan and cross-section illustrations that are schematic illustrations of idealized 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, 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 figures are schematic in nature and their shapes are not intended to 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, an exposure apparatus and an exposure method using the same according to exemplary embodiments of the present invention will be described with reference to the attaching drawings. 
     First, an exposure apparatus according to an exemplary embodiment of the present invention will be described with reference to  FIGS. 1 and 2 .  FIG. 1  is a side view of an exposure apparatus  1  according to an exemplary embodiment of the present invention.  FIG. 2  is a top view of the exposure apparatus  1  shown in  FIG. 1 . 
     Referring to  FIGS. 1 and 2 , the exposure apparatus  1  according to the current exemplary embodiment may include a light source unit  100 , a prism unit  200 , a mask unit  300 , and a substrate stage  400 . A substrate  10 , which is to be exposed to light, is placed on the substrate stage  400 . Here, the substrate  10  may include an exposure area  11 , which is to be exposed to light, and a non-exposure area  12  which is not to be exposed to light. 
     The light source unit  100  irradiates light onto the substrate  10 . To this end, the light source unit  100  may include a light source (not shown) which emits light, and an optical system which includes an exposure lens (not shown). The light source may be, but is not limited to, an Hg lamp (365 nm) or an Nd-YAG laser (355 nm). 
     The prism unit  200  is placed between the light source unit  100  and the substrate stage  400 . The prism unit  200  allows light emitted from the light source unit  100  to pass therethrough and reach the exposure area  11  of the substrate  10 , or blocks the light so as to prevent the light from reaching the non-exposure area  12 . This will be described in more detail below. 
     The mask unit  300  contains a predetermined pattern which is to be transferred onto the exposure area  11  of the substrate  10 . To this end, the mask unit  300  may include a light-blocking portion (not shown) which blocks irradiated light, and a pattern portion  310  (see  FIG. 4 ) which includes a light-passing portion that passes the irradiated light. That is, the pattern portion  310  of the mask unit  300  is shaped so that some parts allow light to pass through, and other parts block light, thus forming the predetermined pattern. Accordingly, the predetermined pattern contained in the pattern portion  310  of the mask unit  300  can be transferred onto the exposure area  11  of the substrate  10 . 
     The exposure apparatus  1  according to the current exemplary embodiment may include a plurality of masks  300 - 1  through  300 - 3 , each having a smaller size than that of the entire substrate  10 . The masks  300 - 1  through  300 - 3  may be arranged in two columns c 1  and c 2  in a zigzag fashion, that is, they may be arranged in an alternating manner. For example, the exposure apparatus  1  according to the current exemplary embodiment may divide one exposure area  11  into, e.g., three sections, and irradiate light to the three sections by using the masks  300 - 1  through  300 - 3 . 
     More specifically, when the exposure area  11  is divided into upper, middle, and lower sections, the upper section of the exposure area  11  may be exposed by the mask  300 - 1  in the first column c 1 , the middle section of the exposure area  11  may be exposed by the mask  300 - 2  in the second column c 2 , and the lower section of the exposure area  11  may be exposed by the mask  300 - 3  in the first column c 1 . Accordingly, even when the size of the substrate  10  increases, the exposure of the substrate  10  can be performed without increasing the overall size of the mask unit  300 . That is, even when the size of the substrate  10  increases, the substrate  10  can be exposed to light by simply increasing the number of relatively small masks  300 - 1  through  300 - 3  that are used. Therefore, there is no need to increase the overall size of the mask unit  300 . This helps reduce mask costs, which, in turn, reduces the overall manufacturing costs. 
     The substrate  10 , which is to be exposed to light by the exposure apparatus  1 , is placed on the substrate stage  400 . The substrate stage  400  may include a holding unit (not shown) to prevent movement of the substrate  10  during the exposure process, so that the substrate  10  can be exposed to light in a more stable manner. 
     During the exposure process, the substrate stage  400  moves the substrate  10  in, for example, a first direction d 1  (see  FIG. 4 ). Thus, even if the light source unit  100  and the mask unit  300  are fixed in place, the entire surface of the substrate  10  can be exposed to light. To this end, the substrate stage  400  may include a substrate-transferring unit (not shown). In addition, the exposure apparatus  1  according to the current exemplary embodiment may include a substrate transferring unit driver (not shown) which drives the substrate-transferring unit. 
     The prism unit  200  included in the exposure apparatus  1  according to the current exemplary embodiment of the present invention will now be described with reference to  FIG. 3 .  FIG. 3  is a diagram illustrating the prism unit  200  included in the exposure apparatus  1  of  FIG. 1 . 
     Referring to  FIG. 3 , the prism unit  200  of the exposure apparatus  1  of  FIG. 1  may include a first prism  210  and a second prism  220 . The first prism  210  includes a first surface  211  upon which light emitted from the light source unit  100  is incident, and a second surface  212  which transmits or reflects the incident light. In this embodiment, the first surface  211  and the second surface  212  form a predetermined angle with respect to each other, and are not parallel. 
     The prism unit  200  may further include the second prism  220 , upon which light that passes through the first prism  210  is incident. Only that light which passes through the first prism  210  can pass through to the second prism  220 . The second prism  220  may be used to increase the “straightness” of light that passes through the first prism  210 . That is, the path of that light which passes through the first prism  210  may not be perpendicular to the substrate  10 , due to the difference between the refractive index of the first prism  210  and that of the space outside the first prism  210 . However, if the light which passes through the first prism  210  is then transmitted through the second prism  220 , the path of the light can be corrected to be perpendicular to the substrate  10 . 
     To this end, the second prism  220  may include a third surface  221  upon which light that passes through the first prism  210  is incident, and a fourth surface  223  from which the light exits. In this embodiment, the third surface  221  and the fourth surface  223  form a predetermined angle with respect to each other and are not parallel. The first prism  210  and the second prism  220  are separated by a predetermined distance, such that the third surface  221  of the second prism  220  is substantially parallel to the second surface  212  of the first prism  210 . The first prism  210  and the second prism  220  may have substantially the same refractive index, perhaps by being made of the same material. For example, when the first prism  210  is made of quartz, the second prism  220  may also be made of quartz. In this case, both of the first and second prisms  210  and  220  may have the refractive index of quartz, i.e., a refractive index of 1.533. 
     When the prism unit  200  overlaps the exposure area  11  of the substrate  10 , light emitted from the light source unit  100  is allowed to pass therethrough, and onto the substrate  10 . On the other hand, when the prism unit  200  overlaps the non-exposure area  12  of the substrate  10 , light emitted from the light source unit  100  is blocked, and does not irradiate the substrate  10 . To this end, the first and second prisms  210  and  220  of the prism unit  200  may be rotated at predetermined angles. That is, the prism unit  200  may be oriented at different angles when it overlaps the exposure area  11  of the substrate  10 , as compared to when it overlaps the non-exposure area  12  of the substrate  10 . This will be described in more detail later. 
     An exposure method using the exposure apparatus  1  of  FIG. 1  will now be described with reference to  FIGS. 4 through 7 .  FIGS. 4 and 5  are diagrams for explaining an exposure method that uses the exposure apparatus  1  of  FIG. 1 .  FIG. 6  is a diagram illustrating a case where the prism unit  200  of the exposure apparatus  1  of  FIG. 1  overlaps the exposure area  11  of the substrate  10 .  FIG. 7  is a diagram illustrating a case where the prism unit  200  of the exposure apparatus  1  of  FIG. 1  overlaps the non-exposure area  12  of the substrate  10 . 
     Referring to  FIGS. 4 and 6 , when the exposure apparatus  1  of  FIG. 1  overlaps the exposure area  11  of the substrate  10 , light is transmitted from the light source unit  100  to the mask unit  300 . 
     Specifically, it is assumed that a first exposure area  11 - 1  and a second exposure area  11 - 2  of the substrate  10  are arranged with the non-exposure area  12  interposed therebetween. When the prism unit  200  of the exposure apparatus  1  overlaps the first exposure area  11 - 1 , the first prism  210  of the prism unit  200  transmits light emitted from the light source unit  100  therethrough, and the transmitted light is incident on the second prism  220  such that its path can be corrected. When the light incident on the second prism  220  passes through the second prism  220 , its path is made generally perpendicular to the substrate  10 . The light that transmits through the second prism  220  passes through the pattern portion  310  of the mask unit  300 , to reach the first exposure area  11 - 1  of the substrate  10 . Here, a width Wm of the pattern portion  310  may be substantially equal to a width Wp of the second prism  220 . Alternatively, the width Wm of the pattern portion  310  may be smaller than the width Wp of the second prism  220 . Accordingly, the light can be prevented from reaching portions of the first exposure area  11 - 1  other than those corresponding to the pattern portion  310 . Therefore, a situation where a pattern different from a pattern formed on the pattern portion  310  is transferred to the first exposure area  11 - 1  (i.e. unwanted light is irradiated upon a portion of area  11 - 1  outside of pattern portion  310 ) can be prevented. 
     For the first prism  210  to transmit light, light incident upon the first prism  210  and the second surface  212  of the first prism  210  must satisfy a predetermined condition. 
     Referring to  FIG. 6 , for the prism unit  200  to transmit light emitted from the light source unit  100 , a first angle θ1 formed by the second surface  212  of the first prism  210  and the light incident upon the first prism  210  must be smaller than a predetermined value, in order to prevent light emitted by the light source unit  100  from reflecting off one of the surfaces of the prisms  210 ,  220  and away from the mask unit  300 . More specifically, the first angle θ1 may be defined as an angle between the light incident upon the first prism  210  and a first normal u 1  of the second surface  212  of the first prism  210 . 
     The size of the first angle θ1 may be determined according to sin −1 (n o /n 1 ), where n 1  indicates the refractive index of the first prism  210 , and n 0  indicates the refractive index of the space outside the first prism  210 . For example, when the first prism  210  is made of quartz and when the refractive index n 0  of the space outside the first prism  210  is one (1.0), the first angle θ1 may be determined by the above equation. That is, since the refractive index of quartz is 1.533, the refractive index n 1  of the first prism  210  may be determined to be 1.533. Accordingly, the size of sin −1 (n o /n 1 ) may be determined to be sin −1 ( 1/1.533), which equals 40.716°. Therefore, for the prism unit  200  to transmit light emitted from the light source unit  100 , the first angle θ1 formed by the light incident upon the first prism  210  and the first normal u 1  of the second surface  212  of the first prism  210  must be smaller than 40.716°. Accordingly, the prism unit  200  may be rotated such that the first angle θ1 of the first prism  210  becomes smaller than 40.716°. 
     As described above, the size of the first angle θ1 is determined by the refractive index n 1  of the first prism  210  and the refractive index n 0  of the space outside the first prism  210 . Therefore, the first angle θ1 should be smaller than 40.716° only when the first prism  210  is made of quartz and the refractive index n 0  of the space outside the first prism  210  is one. Thus, the magnitude of the first angle θ1 is not limited to the above example, and may vary according to the refractive index n 1  of the first prism  210  and the refractive index n 0  of the space outside the first prism  210 . 
     Referring to  FIGS. 5 and 7 , when the exposure apparatus  1  of  FIG. 1  overlaps the non-exposure area  12  of the substrate  10 , it blocks light emitted from the light source unit  100  such that the light cannot proceed toward the mask unit  300 . Consequently, the exposure apparatus  1  prevents the light from reaching the non-exposure area  12  of the substrate  10 . 
     Specifically, it is assumed that the non-exposure area  12  is located between the first exposure area  11 - 1  and the second exposure area  11 - 2  of the substrate  10 . When the prism unit  200  of the exposure apparatus  1  overlaps the non-exposure area  12 , the first prism  210  of the prism unit  200  is oriented so as to substantially reflect all light emitted from the light source unit  100 , thereby preventing the light from reaching the non-exposure area  12 . That is, when the prism unit  200  overlaps the non-exposure area  12 , it is rotated so as to block light from the light source  100 , preventing it from propagating toward the substrate  10 . Thus, the light is unable to enter the second prism  220 . 
     For the first prism  210  to reflect substantially all light from the light source  100 , the light incident upon the first prism  210  and the second surface  212  of the first prism  210  must satisfy a predetermined condition. 
     Referring to  FIG. 7 , for the prism unit  200  to reflect substantially all light emitted from the light source unit  100 , a second angle θ2 formed by the second surface  212  of the first prism  210  and the light incident upon the first prism  210  must be greater than or equal to a predetermined value. Here, the second angle θ2 may be defined as an angle between the light incident upon the first prism  210  and a second normal u 2  of the second surface  212  of the first prism  210 . 
     The size of the second angle θ2 may be determined according to sin −1 (n o /n 1 ), where n 1  indicates the refractive index of the first prism  210 , and n 0  indicates the refractive index of the space outside the first prism  210 . For example, when the first prism  210  is made of quartz and when the refractive index n 0  of the space outside the first prism  210  is one (1.0), the second angle θ2 may be determined to be to be sin −1 ( 1/1.533), which equals 40.716°. Therefore, for the prism unit  200  to substantially reflect all light emitted from the light source unit  100 , the second angle θ2 must be greater than or equal to 40.716°. Accordingly, the prism unit  200  may be rotated such that the second angle θ2 of the first prism  210  becomes greater than or equal to 40.716°. 
     Referring to  FIGS. 6 and 7 , to transmit light, the prism unit  200  may be positioned at a predetermined angle α with respect to the substrate  10 . As above, to reflect light, the prism unit  200  may be rotated to an angle greater than θ2=40.716°. For example, the prism unit  200  may be rotated so that fourth surface  223  is parallel to the substrate  10 . This can also be stated as a rotation of the prism unit  200  by the predetermined angle α. Since the second surface  212  of the first prism  210  is maintained parallel to the third surface  221  of the second prism  220 , the first prism  210  and the second prism  220  may both be simultaneously rotated by the predetermined angle α. The exposure apparatus  1  of  FIG. 1  may further include a prism rotator (not shown) to rotate the prism unit  200 . 
     As described above, the size of the second angle θ2 is determined by the refractive index n 1  of the first prism  210  and the refractive index n 0  of the space outside the first prism  210 . Therefore, the second angle θ2 is greater than or equal to 40.716° only when the first prism  210  is made of quartz and the refractive index n 0  of the space outside the first prism  210  is one. Thus, the size of the second angle θ2 is not limited to the above example, and may vary according to the refractive index n 1  of the first prism  210  and the refractive index n 0  of the space outside the first prism  210 . 
     As described above, the prism unit  200  that overlapped the first exposure area  11 - 1  can also overlap the non-exposure area  12 . To this end, the substrate  10  may be moved in the first direction d 1  by, for example, the substrate stage  400 . Accordingly, the prism unit  200  may successively overlap the first exposure area  11 - 1  and the non-exposure area  12 . If the substrate  10  is moved even further along the first direction d 1 , the prism unit  200  may then overlap the second exposure area  11 - 2 . 
     That is, as the substrate  10  moves in the first direction d 1 , the prism unit  200  sequentially overlaps the first exposure area  11 - 1 , the non-exposure area  12 , and the second exposure area  11 - 2 . Accordingly, the prism unit  200  is rotated so as to, in order, transmit, substantially reflect, and then transmit light emitted from the light source unit  100 . In further detail, when the prism unit  200  overlaps the first exposure area  11 - 1 , it is rotated so as to transmit light from the light source unit  100  to the first exposure area  11 - 1 . When the prism unit  200  overlaps the non-exposure area  12 , it is rotated so as to substantially reflect light from the light source unit  100 , and thus prevent the light from reaching the non-exposure area  12 . When the prism unit  200  overlaps the second exposure area  11 - 2 , it is again rotated so as to transmit light from the light source unit  100  to the second exposure area  11 - 2 . 
     In summary, the exposure apparatus  1  of  FIG. 1  performs the exposure process on the whole surface of the substrate  10 , as the prism unit  200  repeats the operation of repeatedly transmitting and reflecting light emitted from the light source unit  100 . Here, the light source unit  100 , the prism unit  200 , and the mask unit  300  may remain stationary. In this case, the prism unit  200  may be rotated according to whether it overlaps the exposure area  11  or the non-exposure area  12  of the substrate  10  so as to transmit or totally reflect light emitted from the light source unit  100 . 
     As described above, since the prism unit  200  transmits or reflects light during the exposure process as desired, light can be prevented from irradiating some areas of the substrate  10 , thus reducing or preventing stain defects resulting from differences in exposure. 
     Further, the exposure apparatus  1  of  FIG. 1  and the exposure method using the same are employed to perform the exposure process on the substrate  10  by simply rotating the prism unit  200 , without moving the prism unit  200  in the first direction d 1  and without a loss in the amount of light that is allowed to enter the exposure area  11 . 
     Another exposure method using the exposure apparatus  1  of  FIG. 1  will now be described with reference to  FIGS. 8A through 11B .  FIGS. 8A through 11B  are diagrams for explaining another exposure method that uses the exposure apparatus  1  of  FIG. 1 . Here,  FIGS. 8A, 9A, 10A and 11A  are front views of the exposure apparatus  1  performing an exposure process.  FIGS. 8B, 9B, 10B, and 11B  are side views of the exposure apparatus  1  performing the exposure process. 
     Referring to  FIGS. 8A and 8B , light emitted from the light source unit  100  travels directly to the first exposure area  11 - 1  of the substrate  10  without passing through the prism unit  200 . Here, the prism unit  200  is moved to a position that does not overlap the first exposure area  11 - 1 . To this end, the prism unit  200  may be moved parallel to the substrate  10  in the first direction d 1 . 
     Referring to  FIGS. 9A and 9B , during exposure of the first exposure area  11 - 1 , the prism unit  200  may move in a second direction d 2 . As the prism unit  200  moves in the second direction d 2 , it may overlap the first exposure area  11 - 1 . When the prism unit  200  overlaps the first exposure area  11 - 1 , some of the light that is to enter the first exposure area  11 - 1  may be lost. Accordingly, stain defects may be generated in the first exposure area  11 - 1  due to the difference in exposure. 
     To prevent stain defects, when the prism unit  200  is moved so as to overlap first exposure area  11 - 1 , it may also be rotated to transmit light emitted from the light source unit  100 . Accordingly, even when the prism unit  200  overlaps the first exposure area  11 - 1 , light that is to enter the first exposure area  11 - 1  is not lost, and thus the first exposure area  11 - 1  can be exposed to a constant amount of light. In addition, stain defects caused by the difference in exposure are not generated. 
     Referring to  FIGS. 10A and 10B , after the prism unit  200  moves across the first exposure area  11 - 1  in the second direction d 2 , it overlaps the non-exposure area  12 . Here, the substrate  10  continues to move in the first direction d 1 . When prism unit  200  overlaps the non-exposure area  12 , it is rotated so as to substantially reflect light emitted from the light source unit  100 , thus preventing the light from reaching the non-exposure area  12 . As above, the prism unit  200  is rotated so as to switch from a state in which it transmits the light as shown in  FIG. 9A  to a state in which it substantially reflects the light. Since this has been described above in detail, a redundant description thereof will be omitted. Due to the rotation of the prism unit  200 , the light emitted from the light source unit  100  does not reach the non-exposure area  12 . 
     Referring to  FIGS. 11A and 11B , the prism unit  200  may move in the first direction d 1  at the same time that the substrate  10  moves in the first direction d 1 . As the substrate  10  moves in the first direction d 1 , the light source unit  100  and the mask unit  300 , which are stationary, overlap the second exposure area  11 - 2 . Accordingly, light emitted from the light source unit  100  reaches the second exposure area  11 - 2 . The prism unit  200  is moved to a position that does not overlap the second exposure area  11 - 2 . The exposure apparatus  1  performs the exposure process on the substrate  10  by repeating the above process. 
     In summary, during an exposure process, the prism unit  200  moves in the first direction d 1  and then moves in the second direction d 2 , which is opposite the first direction d 1 , before the light source unit  100  overlaps the non-exposure area  12  of the substrate  10 . When the prism unit  200  being moved in the second direction d 2  overlaps the first exposure area  11 - 1 , it is rotated to transmit light such that the light can enter the first exposure area  11 - 1  without loss. When the prism unit  200  being moved in the second direction d 2  overlaps the non-exposure area  12 , it is rotated to totally reflect light such that the light does not enter the non-exposure area  12 . Then, the prism unit  200  moves again in the first direction d 1  to allow light emitted from the light source unit  100  to reach the second exposure area  11 - 2 . During the exposure of the second exposure area  11 - 2 , the prism unit  200  moves again in the second direction d 2  to block light from reaching another non-exposure area  12 . Here, the prism unit  200  transmits light therethrough while being moved in the second direction d 2  across the second exposure area  11 - 2 . That is, the exposure apparatus  1  of  FIG. 1  performs the exposure process as the prism unit  200  transmits or totally reflects light while being moved in the first or second direction d 1  or d 2 . Accordingly, the exposure process can be performed without generating stain defects. 
     In other words, the prism unit  200  is first moved out from under the light source unit  100  (along direction d 1 ), so that the light source unit  100  directly illuminates the first exposure area  11 - 1 . As the substrate  10  gradually moves in direction d 1 , light from the light source unit  100  effectively moves in the opposite direction, toward non-exposure area  12 . As it does, prism unit  200  is moved back under the light source unit  100 . While the light illuminates the first exposure area  11 - 1 , the prism unit  200  is rotated so as to transmit light. Once the light moves onto the non-exposure area  12 , the prism unit  200  is rotated so as to block light from the light source unit  100 , preventing light from irradiating the non-exposure area  12  and thus preventing stain defects. When the light passes over area  12  and onto the second exposure area  11 - 2 , the prism unit  200  is again moved out from under the light source unit  100 , so that the light source unit  100  directly illuminates the second exposure area  11 - 2 . This process then repeats for further exposure and non-exposure areas, preventing stain defects across the substrate  10 . 
     While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it will be understood by those of ordinary skill in the art that various changes in form and detail may be made therein without departing from the spirit and scope of the present invention as defined by the following claims. The exemplary embodiments should be considered in a descriptive sense only and not for purposes of limitation.