Abstract:
A method of aligning a mask assembly includes: providing a mask assembly including a mask and a mask frame; and adjusting the mask frame by independently moving at least a position of a lower portion of the mask frame and an upper portion of the mask frame.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims priority to and the benefit of Korean Patent Application No. 10-2013-0109367, filed on Sep. 11, 2013 in the Korean Intellectual Property Office, the entire content of which is incorporated herein by reference. 
     BACKGROUND 
     1. Field 
     Aspects of embodiments of the present invention relate to an aligning method of a mask assembly by using a deposition apparatus. 
     2. Description of the Related Art 
     As a flat panel display, a liquid crystal display (LCD) and an organic light emitting diode (OLED) display are known. The flat panel display includes a metal layer with a predetermined pattern, and an organic emission layer of the predetermined pattern is formed for every pixel in a case of the organic light emitting diode (OLED) display. A deposition method using a mask for forming the metal layer and the organic emission layer may be applied. 
     The mask causes non-uniformity of a pattern opening of the mask and a reduction of pixel position accuracy (PPA) as a size of the flat panel display is increased. 
     The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention, and, therefore, it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art. 
     SUMMARY 
     According to aspects of embodiments of the present invention, a deposition apparatus controls a decrease and increase of a tensile force applied to a mask and prevents or substantially prevents a twist of a mask frame, and an aligning method of a mask assembly using the same is provided. 
     According to an aspect of embodiments of the present invention, an aligning method of a mask assembly by using a deposition apparatus including a thin film deposition mask assembly used in a deposition process of a thin film, such as an organic emission layer or a metal layer, is provided. 
     According to one or more exemplary embodiments of the present invention, a method of aligning a mask assembly using a deposition apparatus includes: providing a mask assembly including a mask and a mask frame; and adjusting the mask frame by independently moving at least a position of a lower portion of the mask frame and an upper portion of the mask frame. 
     In the adjusting of the mask frame, the upper portion and the lower portion of the mask frame may be equally moved by using a lower frame position controller and an upper frame position controller installed to a mask stage fixing the mask assembly to increase or decrease a tensile force applied to the mask. 
     In the adjusting of the mask frame, a position of the upper portion of the mask frame may be moved farther than a position of the lower portion of the mask frame by using a lower frame position controller and an upper frame position controller installed to a mask stage fixing the mask assembly to control a twist of the mask frame. 
     The lower frame position controller may be connected to a lower portion of the mask stage, and the upper frame position controller may be connected to an upper portion of the mask stage. 
     The lower frame position controller may include a lower supporter, a lower driver installed to the lower supporter and configured to generate a first driving force, and a lower driving force transmission unit connected to the lower driver to control the position of the lower portion of the mask frame by using the first driving force, and the upper frame position controller may include an upper supporter, an upper driver installed to the upper supporter and configured to generate a second driving force, and an upper driving force transmission unit connected to the upper driver to control the position of the upper portion of the mask frame by using the second driving force. 
     The lower driver and the upper driver may include motors, and the lower driving force transmission unit and the upper driving force transmission unit may include screw-thread portions. The method may further include installing a dust proofer to the lower frame position controller and the upper frame position controller. 
     At least one of the lower frame position controller or the upper frame position controller may be provided in plural in a number different from a number of the other of the lower frame position controller or the upper frame position controller. 
     According to an aspect of embodiments of the present invention, the deposition apparatus installs the lower frame position controller connected under the mask stage and the upper frame position controller connected on the mask stage such that the upper portion and the lower portion of the mask frame may be moved by using the lower frame position controller and the upper frame position controller, and thereby the position of the upper portion of the mask frame may be moved farther than the position of the lower portion of the mask frame. Accordingly, in the mask frame twisted by the tensile force, the twist may be eliminated or reduced. Accordingly, the increased interval between the mask and the substrate caused by the twist deformation of the mask frame may be compensated or reduced. 
     According to another aspect of embodiments of the present invention, the interval between the mask and the substrate may be reduced such that a defect in the deposition process due to an increase of the blocking region covered by the mask may be minimized or reduced. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a top view of a deposition apparatus according to an exemplary embodiment of the present invention. 
         FIG. 2  is a side view of the deposition apparatus of  FIG. 1 . 
         FIG. 3  and  FIG. 4  are views sequentially showing an aligning method of a mask assembly using a deposition apparatus, according to an exemplary embodiment of the present invention, as a method of aligning the mask assembly by removing a twist of a mask frame. 
         FIG. 5  and  FIG. 6  are views sequentially showing an aligning method of a mask assembly using a deposition apparatus, according to an exemplary embodiment of the present invention, as a method of aligning the mask assembly through a horizontal direction movement of a mask frame. 
         FIG. 7  is a top view of a deposition apparatus according to another exemplary embodiment of the present invention. 
         FIG. 8  is a top view of a deposition apparatus according to another exemplary embodiment of the present invention. 
       
         
           
                 
               
                 
                 
               
             
                 
                     
                 
                 
                   Description of Reference Numerals Indicating Some Elements in the Drawings 
                 
                 
                     
                 
               
               
                 
                     
                 
               
            
             
                 
                   20: mask 
                   30: mask frame 
                 
                 
                   40: mask stage 
                   50: frame position controller 
                 
                 
                   51: lower frame position controller 
                   52: upper frame position controller 
                 
                 
                   60: dust proofer 
                 
                 
                     
                 
               
            
           
         
       
     
    
    
     DETAILED DESCRIPTION 
     The present invention is described more fully hereinafter with reference to the accompanying drawings, in which some exemplary embodiments of the present invention are shown. As those skilled in the art would realize, the described embodiments may be modified in various different ways, all without departing from the spirit or scope of the present invention. Accordingly, the drawings and description are to be regarded as illustrative in nature and not restrictive. 
     In the specification, unless explicitly described to the contrary, the word “comprise” and variations such as “comprises” or “comprising” are to be understood to imply the inclusion of stated elements but not the exclusion of any other elements. In addition, it is to be understood that when an element, such as a layer, film, region, or substrate, is referred to as being “on” another element, it may be directly on the other element or intervening elements may also be present. In contrast, when an element is referred to as being “directly on” another element, it is to be understood that there are no intervening elements present. Further, in the specification, it is to be understood that the word “on” means positioning on or below the object portion, and does not only mean positioning on the upper side of the object portion based on a gravity direction. 
       FIG. 1  is a top view of a deposition apparatus according to an exemplary embodiment of the present invention; and  FIG. 2  is a side view of the deposition apparatus of  FIG. 1 . 
     As shown in  FIG. 1  and  FIG. 2 , a deposition apparatus according to an exemplary embodiment of the present invention includes a deposition chamber  1 , a deposition source  10 , a mask  20 , a mask frame  30 , at least one mask stage  40 , at least one frame position controller  50 , and a fixing member  70  fixing the frame position controller  50  to the deposition chamber  1 . 
     The deposition chamber  1  maintains a vacuum while a deposition process is performed in the deposition chamber  1 . 
     The deposition source  10  is installed inside the deposition chamber  1  and sprays a deposition material. The deposition source  10 , in one embodiment, sprays the deposition material upward by heating a deposition container filled with the deposition material by using a heating member. The deposition source  10 , in one embodiment, may be provided in plural in the deposition chamber  1 . 
     The mask  20  is spaced from the deposition source  10  such that the deposition material is deposited with a predetermined pattern, The mask  20 , in one embodiment, is a thin metal quadrangular plate having a length (L) and a width (W), and a plurality of pattern openings  20   a . The pattern openings  20   a  are formed having a same shape as a thin film to be deposited. Accordingly, in the deposition process, the deposition material passes through the pattern openings  20   a  and is deposited on the substrate  100 , thereby forming a thin film (e.g., a metal layer, an organic emission layer, etc.) of a desired shape and pattern. 
     The mask  20  is positioned over the deposition source  10 , and the substrate  100 , in one embodiment, is positioned above and spaced apart from the mask  20  by a distance (e.g., a predetermined distance) (d). 
     The mask frame  30  supports the mask  20  and has a shape (e.g., a square shape) that is larger than a size of the mask  20 , and the mask  20  is fixed to the mask frame  30 , such as by welding. 
     The mask frame  30 , in one embodiment, has four edges forming a square frame shape, and the four edges respectively include a frame upper surface  30   a  contacting the mask  20 . The mask frame  30  extends in a downward direction from the frame upper surface  30   a  and has a predetermined height (h), such that an end closer to the frame upper surface  30   a  is an upper portion  32  of the mask frame  30 , and an end farther from the frame upper surface  30   a  is a lower portion  31  of the mask frame  30 . 
     In one embodiment, in a state of extending the mask  20 , a mask assembly is completed by welding the mask  20  onto the mask frame  30 . In the deposition apparatus, the mask frame  30  may be manufactured of one fixed body while having high processing accuracy. Accordingly, in one embodiment, after the mask  20  is extended and welded, the tensile force applied to the mask  20  may not be increased or decreased. As described above, since the increasing or decreasing of a tensile force to the mask  20  may not be made, much time and effort are required in the tensile process of the mask  20  and the welding process on the mask frame  30 , and if the tensile process and the welding process of the mask  20  are abnormally performed, the used mask  20  must be discarded. Further, when the mask and the mask frame are used for performing the deposition process, non-uniformity of a size of opening in the mask and a reduction of a pixel position precision may be generated, and, in this instance, the mask that is extended and welded on the mask frame  30  may be separated from the mask frame to be discarded. According to an embodiment of the present invention, to avoid discarding of the mask  20 , the mask frame  30  is capable of increasing or decreasing a tensile force applied to the mask  20 . However, in a method of increasing or decreasing the tensile force with a same moving amount for one entire edge of the mask frame, when requiring a partial change of the mask, the method does not correspond to this case, and while the increasing or decreasing of the tensile force is possible, a twist of the mask frame  30  may not be avoided. 
     That is, a center portion of the mask may sag downward by the weight of the mask  20 , and, accordingly, to prevent or substantially prevent the pattern opening  20   a  of the mask  20  from being changed, the mask  20  is attached to the mask frame  30  by welding in a state of extending both sides of the mask  20  in opposite directions such that a torsion with which the mask frame  30  is twisted is generated in the mask frame  30  when viewing a cross-section of the mask frame  30 . Accordingly, the mask frame  30  is inclined and the upper portions  32  of four edges of the mask frame  30  are closer than the lower portion  31  such that the mask frame  30  is twisted. 
     Accordingly, in a case of using the mask assembly in the deposition apparatus, the mask  20  is positioned at a lower position than the predetermined position by the tension of the mask frame  30  such that an interval between the substrate to be deposited by the deposition material and the mask  20  is increased compared with a predetermined value. As described above, when the interval between the substrate and the mask  20  is increased, a blocking region covered by the mask  20  is increased such that the deposition material is deposited with a wider position than the deposition region, thereby generating a defect in the deposition process. The mask stage  40  includes a stage groove  40   a  to which the mask frame  30  is fixed to fix four edges of the mask frame  30 . The mask frame  30  is inserted into the stage groove  40   a  to be fixed to the mask stage  40 . One or more mask stages  40  may be installed to one edge of the mask frame  30 . 
     At least one frame position controller  50  controls the position of the mask frame  30 . The frame position controller  50  includes a lower frame position controller  51  connected to a lower portion  41  of the mask stage  40 , and an upper frame position controller  52  connected to an upper portion  42  of the mask stage  40 . 
     The lower frame position controller  51 , in one embodiment, includes a lower supporter  511 , a lower driver  512  installed to the lower supporter  511  and generating a driving force, and a lower driving force transmission unit  513  connected to the lower driver  512  and controlling the position of the mask frame  30  by using the driving force. 
     The lower supporter  511 , in one embodiment, may be a frame having a hexahedral shape, and the lower driver  512  is installed and fixed in the lower supporter  511 . One end  5131  of the lower driving force transmission unit  513  is connected to the lower driver  512 , and the other end  5132  of the lower driving force transmission unit  513  is coupled to a threaded groove  40   b  formed in the lower portion  41  of the mask stage  40 . 
     The upper frame position controller  52 , in one embodiment, includes an upper supporter  521 , an upper driver  522  installed to the upper supporter  521  and generating a driving force, and an upper driving force transmission unit  523  connected to the upper driver  522  and controlling the position of the mask frame  30  by using the driving force. 
     The upper supporter  521 , in one embodiment, may be a frame having a hexahedral shape, and the upper driver  522  is installed and fixed in the upper supporter  521 . One end  5231  of the upper driving force transmission unit  523  is connected to the upper driver  522 , and the other end  5232  of the upper driving force transmission unit  523  is coupled to the threaded groove  40   b  formed in the upper portion  42  of the mask stage  40 . 
     The lower driver  512  and the upper driver  522  may be motors, and the lower driving force transmission unit  513  and the upper driving force transmission unit  523  may be screw-thread portions. 
     By rotating the screw-thread portion of the upper driving force transmission unit  523  by using the upper driver  522 , the upper portion  42  of the mask stage  40  attached to the upper driving force transmission unit  523  may be moved toward the side of the deposition chamber  1 , and by rotating the screw-thread portion of the lower driving force transmission unit  513  by using the lower driver  512 , the lower portion  41  of the mask stage  40  attached to the lower driving force transmission unit  513  may be moved toward the center of the mask  20 . 
     As described above, by independently moving the positions of the upper portion  32  and the lower portion  31  of the mask frame  30  by using the lower frame position controller  51  and the upper frame position controller  52 , the position of the upper portion  32  of the mask frame  30  may be controlled to be different from the lower portion  31  of the mask frame  30 . Accordingly, the tensile force of the mask frame  30  twisted by an imbalance of the tensile force applied to the upper portion  32  and the lower portion  31  of the mask frame  30  may be controlled to be uniform or substantially uniform. 
     Accordingly, the interval or distance (d) between the mask  20  and the substrate  100  that is increased by the tension deformation of the mask frame  30  may be compensated. 
     Also, the positions of the upper portion  32  and the lower portion  31  of the mask frame  30  may be equally moved by using the lower frame position controller  51  and the upper frame position controller  52 . 
     By rotating the upper driving force transmission unit  523  by using the upper driver  522 , the upper portion  42  of the mask stage  40  attached to the upper driving force transmission unit  523  may be moved toward the side of the deposition chamber  1 , and by rotating the lower driving force transmission unit  513  by using the lower driver  512 , the lower portion  41  of the mask stage  40  attached to the lower driving force transmission unit  513  may be moved toward the side of the deposition chamber  1  like the upper portion  42 . Also, by rotating the upper driving force transmission unit  523  by using the upper driver  522 , the upper portion  42  of the mask stage  40  attached to the upper driving force transmission unit  523  may be moved toward the center of the mask  20 , and by rotating the lower driving force transmission unit  513  by using the lower driver  512 , the lower portion  41  of the mask stage  40  attached to the lower driving force transmission unit  513  may be moved toward the center of the mask  20  like the upper portion  42 . 
     In this case, a horizontal direction force may be applied to the mask frame  30  such that the tensile force applied to the mask  20  extended and welded to the mask frame  30  may be controlled, thereby controlling the position of the pattern openings  20   a  of the mask  20 . 
     As described above, the tensile force may be additionally increased or decreased to the mask  20  by using the lower frame position controller  51  and the upper frame position controller  52 , such that time and effort required for the initial tensile and welding process between the mask  20  and the mask frame  30  may be reduced. 
     Further, if the initial tensile and welding processes between the mask  20  and the mask frame  30  are not performed with desired accuracy, instead of the mask  20  being separated from the mask frame  30  to be discarded, the tensile force applied to the mask  20  may be increased or decreased by using the lower frame position controller  51  and the upper frame position controller  52 , the accuracy of the mask  20  may be adjusted to the desired value, and the size and the uniformity of the pattern opening of the mask  20  and the pixel position accuracy (PPA) may be controlled, thereby minimizing or reducing a number of discarded masks, and a time for the mask replacement is reduced such that continuous processing time of the deposition apparatus is increased, thereby improving productivity. 
     In one embodiment, the lower frame position controller  51  and the upper frame position controller  52  are installed with dust proofers  60  respectively extended from the lower supporter  511  and the upper supporter  521  and covering the lower driver  512  and the lower driving force transmission unit  513 , and the upper driver  522  and the upper driving force transmission unit  523 . The dust proofer  60  prevents or substantially prevents particles such as dust generated in the lower driver  512 , the upper driver  522 , the lower driving force transmission unit  513 , and the upper driving force transmission unit  523  from being deposited on the substrate  100 . In one embodiment, the dust proofer  60  as a structure for shielding the lower driver  512 , the upper driver  522 , the lower driving force transmission unit  513 , and the upper driving force transmission unit  523  from the outside may include an O-ring or a bellow valve. 
     An aligning method of a mask assembly using a deposition apparatus, according to an exemplary embodiment of the present invention, is described below with reference to  FIG. 3  to  FIG. 6 . 
       FIG. 3  and  FIG. 4  are views sequentially showing an aligning method of a mask assembly using a deposition apparatus, according to an exemplary embodiment of the present invention, as a method of aligning the mask assembly by removing a twist of a mask frame; and  FIG. 5  and  FIG. 6  are views sequentially showing an aligning method of a mask assembly using a deposition apparatus, according to an exemplary embodiment of the present invention, as a method of aligning the mask assembly through a horizontal direction movement of a mask frame. 
     As shown in  FIG. 3 , in the state that the mask frame  30  is twisted by the tensile force applied to the mask  20 , as shown in  FIG. 4 , by using the lower frame position controller  51  and the upper frame position controller  52 , the upper portion  32  of the mask frame  30  is moved farther than the lower portion  31 , thereby removing the tension of the mask frame  30 . 
     Also, as shown in  FIG. 5 , by using the lower frame position controller  51  and the upper frame position controller  52 , the positions of the lower portion  31  and the upper portion  32  of the mask frame  30  are equally moved to increase the tensile force applied to the mask  20 , or as shown in  FIG. 6 , to decrease the tensile force applied to the mask  20 . 
     In one exemplary embodiment, the lower frame position controller and the upper frame position controller are installed in plural to one edge of the mask frame  30 . However, in another exemplary embodiment, one lower frame position controller and one upper frame position controller may be installed to one edge of the mask frame  30 . 
       FIG. 7  is a top view of a deposition apparatus according to another exemplary embodiment of the present invention. 
     The exemplary embodiment shown in  FIG. 7  is substantially the same as an exemplary embodiment shown in  FIG. 1  and  FIG. 2 , except for the number of the lower frame position controllers and the upper frame position controllers, and repeated description of same components is therefore omitted. 
     As shown in  FIG. 7 , the mask stage  40  fixing the mask frame  30  of the deposition apparatus according to another exemplary embodiment of the present invention is installed one by one to each edge of the mask frame  30 . Also, one frame position controller  50 ′ is connected to the mask stage  40  installed to each edge. The frame position controller  50 ′ includes a supporter  501 , a driver  502  installed to the supporter  501  and generating a driving force, and a driving force transmission unit  503  connected to the driver  502  and controlling the position of the mask frame  30  by using the driving force. 
     As described above, by installing the frame position controller  50 ′ to the mask stage  40  one by one to each edge of the mask frame  30 , the tensile force that is increased or decreased to the mask  20  may be easily controlled. 
     Although not shown, in the exemplary embodiment shown in  FIG. 7 , the number of lower frame position controllers and upper frame position controllers may be the same. That is, in  FIG. 7 , the frame position controllers  50 ′ shown are upper frame position controllers, and lower frame position controllers are also included to correspond to the upper frame position controllers. However, in another embodiment, the number of the lower frame position controllers and a number of the upper frame position controllers may be different, as described below. 
       FIG. 8  is a top view of a deposition apparatus according to another exemplary embodiment of the present invention. 
     The exemplary embodiment shown in  FIG. 8  is substantially the same as the exemplary embodiment shown in  FIG. 1  and  FIG. 2 , except for the lower frame position controller and the upper frame position controller having a different number, and repeated description of same components is therefore omitted. 
     As shown in  FIG. 8 , a frame position controller  50 ″ of a deposition apparatus according to another exemplary embodiment of the present invention includes the lower frame position controller  51  connected to a lower portion of the mask stage  40  and the upper frame position controller  50 ′ connected to an upper portion of the mask stage  40 . 
     The number of lower frame position controllers  51  and the number of upper frame position controllers  50 ′ may be different. In  FIG. 8 , the number of lower frame position controllers  51  is two, and the number of upper frame position controllers  50 ′ is one. 
     As described above, by differentiating the numbers of the lower frame position controller  51  and the upper frame position controller  50 ′, the twist of the mask frame  30  may be further easily controlled. 
     While this invention has been described in connection with what are presently considered to be some practical exemplary embodiments, it is to be understood that, the invention is not limited to the disclosed embodiments, but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims and equivalents thereof.