Abstract:
A mask adhesion unit for a deposition apparatus includes a magnetic assembly, a cap plate spaced apart from the magnetic assembly, and a magnetic control unit between edges of the magnetic assembly, and the cap plate. A deposition apparatus using the same is capable of adhering a substrate and a mask assembly together using the mask adhesion unit to improve deposition precision, while preventing deformation of a slit of the mask assembly.

Description:
BACKGROUND 
       [0001]    1. Field 
         [0002]    Embodiments relate to a mask adhesion unit and a deposition apparatus using the same and, more particularly, to a mask adhesion unit and a deposition apparatus using the same that are capable of preventing deformation of a slit of the mask assembly. 
         [0003]    2. Description of the Related Art 
         [0004]    Flat panel display devices, e.g., a liquid crystal display (LCD) device and an organic light emitting diode (OLED) display device, have been used as alternative display devices of cathode ray tube (CRT) display devices because they are light and slim. The OLED display device has many advantages over the LCD display device. For example, the OLED display device has better brightness and larger viewing angle than the LCD display device, while having a super-slim structure since a backlight unit can be removed. 
         [0005]    The OLED display device is a display device using a phenomenon in which an electron injected from a cathode into an organic thin film is re-coupled to a hole injected from an anode to form an exciton, which emits lights. 
         [0006]    To selectively form the cathode, anode, organic thin film, etc., on a substrate formed of, e.g., glass, stainless steel or synthetic resin, a photolithography method or a deposition method is used. The deposition method uses a mask assembly having a pattern including a plurality of slits. In the photolithography method, where photoresist is applied to a certain region of the substrate and then wet-etched or dry-etched, moisture may be introduced into the photoresist during a photoresist separation process or an etching process. Therefore, when organic thin film is formed of a material which may be deteriorated by moisture, the deposition method using a mask assembly may be used. 
         [0007]    The OLED display device includes OLEDs having R, G, and B organic emission layers to display full-color. For example, during formation of the OLED display device via a conventional deposition method, a mask assembly having a plurality of openings may be aligned on a substrate on which a deposition material, e.g., R, G, and B organic emission layers for the OLEDs, is to be formed. Then, the R, G, and B organic emission layers may be provided onto the substrate through the openings of the mask assembly to deposit a desired pattern on the substrate. As a result, the OLED including the R, G, and B organic emission layers may be formed at a certain region of the substrate. 
         [0008]    A deposition apparatus using a conventional mask assembly may include a mask adhesion unit having a magnetic material to adhere the mask assembly and the substrate. However, the magnetic material in the conventional mask adhesion unit may exert non-uniform magnetic force on the mask assembly, thereby causing mask assembly deformation. 
       SUMMARY OF THE INVENTION 
       [0009]    Embodiments are therefore directed to a mask adhesion unit and deposition apparatus using the same, which substantially overcome one or more of the problems due to the limitations and disadvantages of the related art. 
         [0010]    It is therefore a feature of an embodiment to provide a mask adhesion unit and a deposition apparatus using the same that are capable of minimizing disproportional application of a magnetic force to a mask assembly by a magnetic material of the mask adhesion unit to prevent deformation of a slit of the mask assembly. 
         [0011]    At least one of the above and other features and advantages may be realized by providing a mask adhesion unit for a deposition apparatus, including a magnetic assembly, a cap plate spaced apart from the magnetic assembly, and a magnetic control unit between edges of the magnetic assembly and the cap plate. 
         [0012]    The magnetic control unit may include a magnetic shielding material or a ferrite magnetic material. 
         [0013]    The magnetic control unit may include a ferrite magnetic material, the magnetic control unit being a thin film sheet formed of steel. 
         [0014]    The magnetic control unit may overlap two surfaces of the magnetic assembly. 
         [0015]    A portion of the magnetic control unit may be between the magnetic assembly and the cap plate. 
         [0016]    The cap plate may have a plurality of coolant passages. 
         [0017]    The magnetic assembly may include a magnetic plate and a magnetic material applied to a surface of the magnetic plate facing the cap plate. 
         [0018]    The magnetic control unit may overlap two surfaces of the magnetic material, the magnetic control unit covering a side surface of the magnetic material. 
         [0019]    The magnetic material of the magnetic assembly may be a metal-based material. 
         [0020]    At least one of the above and other features and advantages may also be realized by providing a deposition apparatus, including a chamber, a deposition source in the chamber, a mask assembly over the deposition source, and a mask adhesion unit over the mask assembly, wherein the mask adhesion unit includes a magnetic assembly, a cap plate spaced from the magnetic assembly, and a magnetic control unit between edges of the magnetic assembly and the cap plate. 
         [0021]    The magnetic control unit may include a magnetic shielding material or a ferrite magnetic material. 
         [0022]    The magnetic control unit may include a ferrite magnetic material, the magnetic control unit being a thin film sheet formed of steel. 
         [0023]    The cap plate may have a plurality of coolant passages. 
         [0024]    The magnetic assembly may include a magnetic plate and a magnetic material applied to a surface of the magnetic plate facing the cap plate. 
         [0025]    The magnetic material of the magnetic assembly may be a metal-based material. 
         [0026]    The mask assembly may include a mask frame having an opening and at least one pattern mask extending to be fixed to the mask frame. 
         [0027]    The pattern mask may be a fine metal mask. 
         [0028]    The mask frame may be formed of a metal material. 
         [0029]    The deposition apparatus may further include a mask holder for coupling the mask assembly to the chamber. 
         [0030]    The mask holder may have a plurality of coolant passages. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0031]    The above and other features and advantages will become more apparent to those of ordinary skill in the art by describing in detail exemplary embodiments with reference to the attached drawings, in which: 
           [0032]      FIG. 1  illustrates a schematic view of a deposition apparatus in accordance with an exemplary embodiment; and 
           [0033]      FIG. 2  illustrates an enlarged view of a mask assembly and a mask adhesion unit of  FIG. 1 . 
       
    
    
     DETAILED DESCRIPTION 
       [0034]    Korean Patent Application No. 10-2009-0013958, filed on Feb. 19, 2009, in the Korean Intellectual Property Office, and entitled: “Mask Adhesion Unit and Deposition Apparatus Using the Same,” is incorporated by reference herein in its entirety. 
         [0035]    Example embodiments will now be described more fully hereinafter with reference to the accompanying drawings; however, they may be embodied in different forms and should not be construed as 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 scope of the invention to those skilled in the art. 
         [0036]    In the drawing figures, the dimensions of layers and regions may be exaggerated for clarity of illustration. It will also be understood that when a layer or element is referred to as being “on” another layer or substrate, it can be directly on the other layer or substrate, or intervening layers may also be present. Further, it will be understood that when a layer is referred to as being “under” another layer, it can be directly under, and one or more intervening layers may also be present. In addition, it will also be understood that when a layer is referred to as being “between” two layers, it can be the only layer between the two layers, or one or more intervening layers may also be present. Like reference numerals refer to like elements throughout. 
         [0037]      FIG. 1  illustrates a schematic view of a deposition apparatus in accordance with an exemplary embodiment, and  FIG. 2  illustrates an enlarged view of a mask assembly and a mask adhesion unit of  FIG. 1 . 
         [0038]    Referring to  FIG. 1 , the deposition apparatus in accordance with an exemplary embodiment may include a chamber  100 , a deposition source  110  disposed in the chamber  100 , a mask assembly  200  disposed over the deposition source  110 , and a mask adhesion unit  300  disposed over the mask assembly  200 . Here, the deposition apparatus in accordance with an exemplary embodiment may further include a mask holder  130  disposed between the mask assembly  200  and a coupling member  120  to readily couple the mask assembly  200  to the chamber  100  and to prevent damage to the mask assembly  200  during the coupling process. The mask holder  130  may be disposed next to a mask frame  220  of the mask assembly  200 . The coupling member  120  of the chamber  100  may have a bent shape. 
         [0039]    As illustrated in  FIGS. 1 and 2 , the mask assembly  200  may include the mask frame  220  having an opening and one or a plurality of pattern masks  210  extending to be fixed to the mask frame  220 . Each pattern mask  210  may have one or a plurality of slits (not shown) corresponding to the opening of the mask frame  220  so that a deposition material injected or evaporated from the deposition source  110  may be patterned and deposited on a substrate S. In a deposition method using the mask assembly  200 , the pattern masks  210  of the mask assembly  200  may be very precisely aligned, and that the mask assembly  200  may be maximally adhered to the substrate S to improve deposition precision of a material deposited on the substrate S through the pattern masks  210  of the mask assembly  200 . 
         [0040]    The pattern mask  210  may be a fine metal mask (FMM) formed of, e.g., a metal thin film, which may be formed of at least one of steel use stainless (SUS), invar, nickel, cobalt, or an alloy thereof. 
         [0041]    The mask frame  220  may be formed of, e.g., a material resistant to deformation from a compression force, i.e., a strong metal material, to minimize deformation when the pattern mask  210  is fixed to the mask frame  220 . For example, the mask frame  220  may be formed of the same material as the pattern mask  210  to be readily fixed to the pattern mask  210 . Here, to prevent deformation of the mask assembly  200  during the deposition process due to heat in the chamber  100 , a coolant passage (not shown) may be formed in the mask frame  220  of the mask assembly  200 . The coolant passage may provide a passage in which coolant, e.g., cooling water, etc., may flow to cool the mask assembly  200 . The mask frame  220  may have a plurality of coolant passages. When the deposition apparatus in accordance with an exemplary embodiment includes the mask holder  130 , a coolant passage  135  may be formed in the mask holder  130  to prevent deformation of the mask assembly  200  without changing strength of the mask frame  220 . The coolant passage  135  may provide passage in which cooling water, etc., flows so that the mask assembly  200  may not be deformed due to the heat in the chamber  100 . The mask holder  130  may have a plurality of the coolant passages  135 . 
         [0042]    The mask adhesion unit  300  may be disposed on an opposite side of the mask assembly  200  with respect to the substrate S, so that the substrate S may be interposed between the mask adhesion unit  300  and the mask assembly  200 . Here, the mask adhesion unit  300  may be fixed to the chamber  100  by a fixing member  400 . The mask adhesion unit  300 , i.e., a magnetic assembly  320 , may generate a magnetic force and a magnetic field by which the mask assembly  200  adheres to the substrate S, thereby preventing generation of a shadow on the deposition material injected or evaporated from the deposition source  110 . 
         [0043]    The mask adhesion unit  300  may include a cap plate  310 , the magnetic assembly  320  disposed over the cap plate  310 , and a magnetic control unit  330  disposed between the edges of the magnetic assembly  320  and the cap plate  310 . 
         [0044]    The cap plate  310  may prevent damage to the substrate S, e.g., by the magnetic assembly  320 , when the mask adhesion unit  300  is in contact with the substrate S, and may have a coolant passage  315 , through which coolant, e.g., cooling water, etc., flows, to uniformly maintain the temperature of the substrate S. The coolant passage  315  may be a plurality in number, having a predetermined space between the adjacent coolant passages  315 . The cap plate  310  may be between the magnetic assembly  320  and the substrate S, and may overlap e.g., the entire substrate S. 
         [0045]    The magnetic assembly  320  may include a magnetic plate  322  and a magnetic material  325  applied to a surface of the magnetic plate  322  facing the cap plate  310 . For example, the magnetic material  325  may be a film, e.g., flat, covering the entire surface of the magnetic plate  322  facing the cap plate  310 . The magnetic material  325  may be formed of, e.g., a rubber or a metal magnetic material. If the magnetic material  325  is formed of the rubber magnetic material, out-gassing may be generated due to the heat in the chamber  100 , thereby decreasing lifespan of an organic emission layer. Therefore, the magnetic material  325  may preferably be formed of the metal magnetic material. 
         [0046]    The magnetic control unit  330  may remove or substantially reduce a magnetic force applied to edges of the mask assembly  200  from the magnetic assembly  320 . The magnetic control unit  330  may include a magnetic shielding material or a ferrite magnetic material, e.g., steel, and may preferably be a thin film sheet formed of, e.g., steel. For example, as illustrated in  FIG. 2 , the magnetic control unit  330  may be bent to cover the edge of the magnetic material  325 , so the magnetic control unit  330  may overlap, e.g., two surfaces of the magnetic material  325 . That is, a first portion of the magnetic control unit  330  may be interposed between the magnetic material  325  and the cap plate  310 , and a second portion of the magnetic control unit  330  may be substantially perpendicular to the first portion to overlap a side surface, e.g., entire side surface, of the magnetic material  325 . For example, the magnetic control unit  330  may overlap, i.e., cover, an entire edge of the magnetic material  325 , e.g., entire perimeter of the magnetic material  325 . For example, the magnetic control unit  330  may be on the magnetic material  325 . 
         [0047]    The deposition process by the deposition apparatus in accordance with an exemplary embodiment will now be described with reference to  FIGS. 1 and 2 . The deposition source may be disposed on the chamber  100 , and the mask assembly  200  may be coupled to the chamber  100  using the mask holder  130 . 
         [0048]    After placing the substrate S on the mask assembly  200 , the magnetic assembly  320  of the mask adhesion unit  300  may be positioned on an opposite side of the mask assembly  200  with respect to the substrate S, which may be interposed therebetween, to apply a magnetic force and a magnetic field so that the mask assembly  200  may be adhered to the substrate S. 
         [0049]    Since the mask adhesion unit  300  includes the magnetic control unit  330  disposed at the edge of the magnetic assembly  320  facing the mask assembly  200 , a magnetic force and a magnetic field generated from the edge of the magnetic assembly  320  may be removed or substantially reduced by the magnetic control unit  330 . As a result, a disproportional application of the magnetic force and magnetic field to the edge of the mask assembly  200  may be eliminated or substantially minimized. In other words, if a magnetic force and magnetic field are stronger at edges of the magnetic material  325  than in a center thereof, the magnetic control unit  330  may minimize magnetic force and magnetic field at edges of the magnetic material  325 , so the magnetic force and magnetic field applied to the mask assembly  200  may be substantially uniform, e.g., magnetic force and field applied at edges and center of the mask assembly  200  may be substantially uniform. Therefore, deformation of the slit, i.e., slits in the pattern mask  210  disposed adjacent to edges of the mask assembly, of the mask assembly  200  may be prevented. 
         [0050]    When the interior of the chamber  100  is heated to a certain temperature to perform the deposition process, coolant, e.g., cooling water, etc., may be introduced through the coolant passage formed in the mask holder  130 , i.e., the coolant passage  135 , and/or through the cap plate  310  of the mask adhesion unit  300 , i.e., the coolant passage  315 , to prevent deformation of the mask assembly  200  and the substrate S due to the heat in the chamber  100 . 
         [0051]    The deposition material may be injected or may be evaporated from the deposition source  110  to be deposited on the substrate S to form a certain pattern by the slits of the mask assembly  200 . 
         [0052]    In the mask adhesion unit and the deposition apparatus using the same in accordance with an exemplary embodiment, the magnetic control unit  330  including a magnetic shielding material or a ferrite magnetic material, e.g., steel, may be disposed at the edge of the magnetic material  325  of the mask adhesion unit  300  facing the mask assembly  200  to reduce or shield the magnetic force being applied to the edges of the mask assembly  200  from the magnetic material  325 , thereby minimizing disproportional application of magnetic force and magnetic field applied to the edges of the mask assembly  200 . 
         [0053]    Since a magnetic force and magnetic field of a magnetic material layer is conventionally stronger at an edge thereof than at a center portion thereof, a larger magnetic force and magnetic field may be applied to an edge portion than a center portion of a mask assembly by the magnetic material layer, and thus, a slit disposed adjacent to an edge of the mask assembly may be deformed. As can be seen from the foregoing, a mask adhesion unit and a deposition apparatus using the same in accordance with an exemplary embodiment may control a magnetic force and magnetic field being applied to an edge of the mask assembly via a magnetic control unit to minimize disproportional application of magnetic force and magnetic field to an edge of the mask assembly, thereby preventing deformation of a slit of the mask assembly. 
         [0054]    Exemplary embodiments have been disclosed herein, and although specific terms are employed, they are used and are to be interpreted in a generic and descriptive sense only and not for purpose of limitation. Accordingly, it will be understood by those of ordinary skill in the art that various changes in form and details may be made without departing from the spirit and scope of the present invention as set forth in the following claims.