Abstract:
A method of forming an alignment layer with a multi-domain is provided. The alignment layer is formed on a substrate. A mask having a transmission part and a shielding part is aligned over the substrate. First and second alignment directions in the alignment layer are formed by irradiating an ion beam onto the substrate at different irradiation angles. Using the aforementioned ion-beam irradiation process eliminates the need for multiple rubbing processes to create the multi-domain alignment layer.

Description:
This application claims the benefit of the Korean Application No. P2003-0030643 filed on May 14, 2003, which is hereby incorporated by reference. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a method of forming an alignment layer of a liquid crystal display (LCD) device, and more particularly, to a method of forming a multi-domain alignment layer by irradiating ion beam. 
     2. Description of the Related Art 
     In general, a cathode ray tube (CRT) has been most widely used among display devices for displaying image information on a screen until now, but has many inconveniences owing to a large volume and weight compared with the display area. 
     With the development of electronic industries, the display device whose usage was limited to a TV Braun tube and so forth, has been expanded for use in a personal computer, a notebook, a wireless terminal, a vehicle instrument panel, an electronic display board and the like. Also, due to the development of information communication technology, since it is possible to transmit a large amount of image information, the importance on a next generation display device capable of processing and displaying the large amount of image information is constantly increasing. 
     Many requirements exist for such a next generation display device; the next generation display device must be lighter, slimmer, shorter and smaller, have a high luminance, a large-sized screen, a low power consumption and a low price. Among such next generation display devices, the LCD is recently gaining in popularity. 
     The LCD has a higher resolution than other flat displays, and a fast response time considerable to that of the CRT in implementing a moving picture. 
     Due to the high brightness, high contrast, low power consumption characteristics, the LCD is widely used in applications such as a monitor of a desktop computer, a monitor of a notebook computer, a television set, a television set for a vehicle, a navigation system and the like. 
     Twisted nematic (TN) mode LCDs have become extremely popular and are widely used at the present time. 
     In the TN mode LCD, directors of liquid crystal molecules adjacent to the lower substrate are perpendicular to directors of liquid crystal molecules adjacent to the upper substrate. 
     When an electric field is not applied, liquid crystal molecules of the TN mode LCD have a structure in which longer axes of the liquid crystal molecules are twisted in a spiral fashion. The liquid crystal molecules have a pitch and are parallel to the substrate. 
     Recently, with the advent of the multimedia era, the LCDs performance requirements are constantly increasing. In response, various technologies for realizing wide viewing angle have been developed. However, such technologies have drawbacks such as an increase in the power consumption of the LCD due to a decrease in the aperture ratio, a decrease of the display quality, and problems involving the fabrication method and the like. 
     In particular, one of the recently developed technologies to secure a wide viewing angle that has rapidly gained popularity is a multi-domain technology in which each unit pixel has regions with different alignment directions. 
     Herein, when a domain is defined as regions where groups of liquid crystal molecules having the same alignment direction exist, it is said that an LCD with a multi-domain structure has several groups of liquid crystal molecules having different alignment directions. 
     Thus, when several domains exist in a unit pixel, the respective domains have different alignment directions of liquid crystal molecules, thereby improving the viewing angle. 
     In particular, the alignment process used to uniformly align liquid crystal molecules is an important factor in determining the normal operation of an LCD and the uniform display characteristic of a picture. Much research has been performed on such alignment processes. 
     A method of forming a multi-domain alignment layer according to the related art will now be described in more detail with reference to  FIGS. 1A through 1E . 
     The method includes coating a thin polymer film, dividing each unit pixel of the coated thin polymer film into multi-domains, aligning the divided multi-domains in different directions. 
     The alignment layer is generally formed of a polyimide-based organic material, and is aligned by a rubbing method. 
     The rubbing method includes: coating a polyimide-based organic material film on a substrate; vaporizing a solvent contained in the coated polyimide-based organic material film at a temperature of 60-80° C.; hardening the polyimide-based organic material film at a temperature of 80-200° C. to form a polyimide alignment layer; and rubbing the polyimide alignment layer using a rubbing cloth such as a velvet in a predetermined direction to form an alignment direction. 
     As shown in  FIG. 1A , an organic film is coated on a substrate  101 , and is rubbed in a right-handed direction of the drawing, thereby forming a first alignment layer  103  with a right-handed alignment direction. 
     As shown in  FIG. 1B , a positive photosensitive resin film  105  is coated on the first alignment layer  103 . 
     Next, as shown in  FIG. 1C , a mask is arranged over the photosensitive resin film  105 , light is irradiated onto the mask, the photosensitive resin film  105  exposed to the light is developed and etched, thereby forming a predetermined pattern. 
     Next, as shown in  FIG. 1D , the exposed portions of the first alignment layer  103  are rubbed in a left-handed direction, thereby having a left-handed alignment direction. 
     Finally, as shown in  FIG. 1E , the photosensitive resin film pattern  105  is removed, thereby forming the alignment layer with a multi-domain structure. 
     However, the related art method of forming a multi-domain alignment layer using the rubbing method is complicated due to the use of the photolithography process. Also, the alignment layer may be damaged by the use of developer, etchant and the like during the photolithography process. Such an alignment layer may show unstable characteristics. 
     SUMMARY OF THE INVENTION 
     Accordingly, the present invention is directed to a method of forming a multi-domain alignment layer that substantially obviates one or more problems due to limitations and disadvantages of the related art. 
     The present invention provides a method of forming a multi-domain alignment layer by irradiating an ion beam, in which a mask, which is patterned to have a predetermined opening condition and provides a proper ion beam irradiation direction, is designed, thereby obtaining the alignment layer fabricated by a simple process and having superior properties. 
     Additional advantages and features of the invention will be set forth in part 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. These 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. 
     A method of forming a multi-domain alignment layer in one embodiment comprises: forming an alignment layer on a substrate; aligning a mask having a transmission part and a shielding part over the substrate; and forming a first alignment direction and a second alignment direction in the alignment layer by irradiating an ion beam onto the substrate at an irradiation angle of θ. 
     It is to be understood that both the foregoing general description and the following detailed description of the present invention are exemplary and explanatory and are intended to provide further explanation of the invention as claimed. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this application, illustrate embodiment(s) of the invention and together with the description serve to explain the principle of the invention. In the drawings: 
         FIGS. 1A through 1E  are sectional views illustrating a method of forming a multi-domain alignment layer according to the related art; 
         FIGS. 2A through 2C  are schematic views of a unit pixel with a multi-domain structure in an LCD according to the present invention; 
         FIG. 3  is a plane view of a mask used in a process of forming an alignment layer by irradiating ion beam according to an embodiment of the present invention; 
         FIGS. 4A and 4B  are sectional views schematically illustrating relationship between a mask and a substrate in irradiating ion beam so as to form a multi-domain alignment layer according to the present invention; 
         FIG. 5  is a flow diagram illustrating a method of forming a multi-domain alignment layer according to an embodiment of the present invention; and 
         FIGS. 6A through 6D  are sectional views schematically illustrating a method of forming a multi-domain alignment layer according to an embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The present invention will now be described more fully with reference to the accompanying drawings, in which exemplary embodiments of the invention are shown. 
       FIGS. 2A through 2C  are schematic views of a unit pixel with a multi-domain structure in an LCD according to the present invention. Specifically,  FIG. 2A  corresponds to a unit pixel, which is divided and aligned into two domains,  FIG. 2B  corresponds to a unit pixel, which is divided and aligned into four domains, and  FIG. 2C  is another embodiment of four domains alignment and corresponds to a unit pixel, which is divided and aligned into four domains. 
     Referring to  FIG. 2A , an LCD with a unit pixel consisting of two domains includes an upper substrate, a lower substrate opposing the upper substrate, and a liquid crystal layer interposed between the upper substrate and the lower substrate. In the LCD, each unit pixel on the upper substrate and the lower substrate is divided into two domains and the two domains are aligned in different directions. 
     Referring to  FIGS. 2B and 2C , in an LCD with a unit pixel having four domains, each unit pixel on the upper substrate and the lower substrate is divided into four domains, and first two divided domains are aligned in a first direction and second remaining two domains are aligned in a second direction different from the first direction. The first two domains and the second two domains are designed in a structure to compensate for each other. 
     In the LCDs with the multi-domain structures described above, when groups of liquid crystal molecules aligned in different directions in a unit pixel region form multi-domains, the viewing angle can be enhanced due to the different alignment directions of the liquid crystal molecules within a unit pixel. 
     In  FIGS. 2B and 2C , a solid line represents an alignment direction of the alignment layer formed on the upper substrate and a dotted line represents an alignment direction of the alignment layer formed on the lower substrate. A large arrow represents a direction of a main viewing angle. By the above construction, each unit pixel has a structure that the divided domains compensate for each other. 
       FIG. 3  is a plan view of a mask used in a process of forming an alignment layer by irradiating ion beam according to an embodiment of the present invention. 
     In  FIG. 3 , the mask  220  includes a transmission part  222  and a shielding part  224  to control transmission of ion beam. The shielding part  224  absorbs or reflects an ion beam such that the ion beam does not arrive on the substrate. 
     The transmission part  222  is shaped in a slit. The transmission part  222  allows transmission of the ion beam, thereby aligning the alignment layer in a particular direction. 
     By using the mask, a desired multi-domain structure may be formed. 
       FIGS. 4A and 4B  are sectional views schematically illustrating the relationship between the mask and substrate when irradiating the substrate with the ion beam so as to form a multi-domain alignment layer according to the present invention. 
     First, as shown in  FIG. 4A , an alignment layer  210  is formed on a substrate  200 . The mask  220   a  has a pattern including a transmission part and a shielding part corresponding to multi-domains of a unit pixel. The mask  220   a  is spaced apart by a predetermined distance from the substrate  200 . 
     An ion beam  230  is irradiated onto the substrate  200  with a predetermined irradiation angle (θ). The ion beam  230  arrives on the substrate  200  after passing through the transmission part or is shielded by the shielding part. 
     The ion beam  230  that has passed through the transmission part of the mask  220   a  and is irradiated on the substrate  200  aligns exposed portions of the alignment layer  210  in a predetermined direction. 
     When a size of a unit pixel is L, a width of the transmission part of the mask  220   a  is w 1 , a width of the shielding part is w 2 , an interval between the alignment layer  210  and the mask  220   a  facing the alignment layer  210  is H, a thickness of the mask  220   a  is D, and an irradiation angle of the ion beam with respect to a direction parallel to the substrate  200  is θ, these parameters have the following relationships: 
     
       
         
           
             
               
                 
                   Equation 
                   ⁢ 
                   
                     
                         
                     
                     ⁢ 
                     
                         
                     
                   
                   ⁢ 
                   1 
                   ⁢ 
                   
                     : 
                   
                 
               
             
             
               
                 
                   
                     tan 
                     ⁢ 
                     
                         
                     
                     ⁢ 
                     θ 
                   
                   = 
                   
                     
                       
                         D 
                         + 
                         H 
                       
                       
                         L 
                         / 
                         4 
                       
                     
                     = 
                     
                       
                         
                           4 
                           ⁢ 
                           D 
                         
                         + 
                         
                           4 
                           ⁢ 
                           H 
                         
                       
                       L 
                     
                   
                 
               
             
             
               
                 
                   Equation 
                   ⁢ 
                   
                     
                         
                     
                     ⁢ 
                     
                         
                     
                   
                   ⁢ 
                   2 
                   ⁢ 
                   
                     : 
                   
                 
               
             
             
               
                 
                   θ 
                   = 
                   
                     
                       tan 
                       
                         - 
                         1 
                       
                     
                     ⁢ 
                     
                       
                         
                           4 
                           ⁢ 
                           D 
                         
                         + 
                         
                           4 
                           ⁢ 
                           H 
                         
                       
                       L 
                     
                     ⁢ 
                     
                         
                     
                     ⁢ 
                     
                       ( 
                       
                         0 
                         ≤ 
                         θ 
                         ≤ 
                         
                           π 
                           2 
                         
                       
                       ) 
                     
                   
                 
               
             
             
               
                 
                   Equation 
                   ⁢ 
                   
                       
                   
                   ⁢ 
                   3 
                   ⁢ 
                   
                     : 
                   
                 
               
             
             
               
                 
                   
                     
                       W 
                       ⁢ 
                       
                           
                       
                       ⁢ 
                       1 
                     
                     + 
                     
                       W 
                       ⁢ 
                       
                           
                       
                       ⁢ 
                       2 
                     
                   
                   = 
                   L 
                 
               
             
             
               
                 
                   Equation 
                   ⁢ 
                   
                       
                   
                   ⁢ 
                   4 
                   ⁢ 
                   
                     : 
                   
                 
               
             
             
               
                 
                   
                     W 
                     ⁢ 
                     
                         
                     
                     ⁢ 
                     1 
                   
                   = 
                   
                     
                       
                         L 
                         2 
                       
                       + 
                       X 
                     
                     = 
                     
                       
                         
                           L 
                           2 
                         
                         + 
                         
                           D 
                           
                             tan 
                             ⁢ 
                             
                                 
                             
                             ⁢ 
                             θ 
                           
                         
                       
                       = 
                       
                         
                           L 
                           2 
                         
                         + 
                         
                           
                             L 
                             * 
                             D 
                           
                           
                             
                               4 
                               ⁢ 
                               D 
                             
                             + 
                             
                               4 
                               ⁢ 
                               H 
                             
                           
                         
                       
                     
                   
                 
               
             
           
         
       
     
     In the above, so as to align a unit pixel into multi-domains having an identical size (L/ 2 ), the mask  220   a  should satisfy the above equation 1. 
     When equation 2 is satisfied by equation 1, the ion beam is irradiated in the form of a straight line, so that a sum of the transmission part of the mask  220   a  and the shielding part of the mask  220   a  becomes equal to the size of the pixel. 
     Also, since the mask  220   a  has the thickness of D, the width w 1  of the transmission part of the mask  220   a  can be expressed by equation 4 when considering a margin X shielded by the thickness D of the mask  220   a  in the size L/ 2  of the alignment layer aligned by the ion beam  230  passing through the transmission part at an irradiation angle. 
     To align the alignment layer in an opposite direction to the initial alignment direction using the mask  220   a  satisfying the equations 1 through 4, the ion beam  230  is irradiated onto the substrate  200  after the substrate  200  is rotated or the mask  220   a  is moved. In the case of the opposite alignment direction, the above equations 1 through 4 should be satisfied. 
     After first portions of the alignment layer  210  are aligned in a first direction by irradiating an ion beam onto the substrate  200  using the mask  220   a  arranged as shown in  FIG. 4A , the mask  220   b  is rearranged as shown in  FIG. 4B  and the ion beam is again irradiated onto the substrate, so that second portions of the alignment layer  210 , which are not exposed to the ion beam during the first irradiation, are aligned in a second direction opposite to the first direction. 
     At this time, since the mask  220   b  has the thickness D and the ion beam  230  is irradiated with an irradiation angle θ, the mask  220   b  is shifted to a direction parallel to the substrate in consideration of the thickness of the mask and the irradiation angle of the ion beam and rearranged to a new position. 
     After the mask  220   b  is rearranged, the ion beam is irradiated onto the substrate  200 , so that the second portions of the alignment layer  210  are aligned in the second direction. 
     The two domains of each unit pixel, which are aligned in different directions, have an identical size of L/ 2 . 
     When assuming that the size L of the unit pixel is constant, since the thickness D of the mask  220   b  and the interval H between the alignment layer  210  and the mask  220   b  are varied, the irradiation angle θ of the ion beam  230  and the width w 1  of the transmission part of the mask  220   b  may be obtained as follows: 
     In equation 2, 
     
       
         
           
             
               
                 
                   
                     
                       lim 
                       
                         h 
                         -&gt; 
                         0 
                       
                     
                     ⁢ 
                     θ 
                   
                   = 
                   
                     
                       
                         lim 
                         
                           h 
                           -&gt; 
                           0 
                         
                       
                       ⁢ 
                       
                           
                       
                       ⁢ 
                       
                         
                           tan 
                           
                             - 
                             1 
                           
                         
                         ⁢ 
                         
                           
                             
                               4 
                               ⁢ 
                               D 
                             
                             + 
                             
                               4 
                               ⁢ 
                               H 
                             
                           
                           L 
                         
                       
                     
                     = 
                     
                       
                         tan 
                         
                           - 
                           1 
                         
                       
                       ⁢ 
                       
                         
                           4 
                           ⁢ 
                           D 
                         
                         L 
                       
                     
                   
                 
               
             
             
               
                 
                   
                     
                       lim 
                       
                         d 
                         -&gt; 
                         0 
                       
                     
                     ⁢ 
                     θ 
                   
                   = 
                   
                     
                       
                         lim 
                         
                           d 
                           -&gt; 
                           0 
                         
                       
                       ⁢ 
                       
                           
                       
                       ⁢ 
                       
                         
                           tan 
                           
                             - 
                             1 
                           
                         
                         ⁢ 
                         
                           
                             
                               4 
                               ⁢ 
                               D 
                             
                             + 
                             
                               4 
                               ⁢ 
                               H 
                             
                           
                           L 
                         
                       
                     
                     = 
                     
                       
                         tan 
                         
                           - 
                           1 
                         
                       
                       ⁢ 
                       
                         
                           4 
                           ⁢ 
                           H 
                         
                         L 
                       
                     
                   
                 
               
             
             
               
                 
                   
                     
                       lim 
                       
                         h 
                         -&gt; 
                         ∞ 
                       
                     
                     ⁢ 
                     θ 
                   
                   = 
                   
                     
                       
                         lim 
                         
                           h 
                           -&gt; 
                           ∞ 
                         
                       
                       ⁢ 
                       
                           
                       
                       ⁢ 
                       
                         
                           tan 
                           
                             - 
                             1 
                           
                         
                         ⁢ 
                         
                           
                             
                               4 
                               ⁢ 
                               D 
                             
                             + 
                             
                               4 
                               ⁢ 
                               H 
                             
                           
                           L 
                         
                       
                     
                     = 
                     
                       π 
                       2 
                     
                   
                 
               
             
             
               
                 
                   
                     
                       lim 
                       
                         d 
                         -&gt; 
                         ∞ 
                       
                     
                     ⁢ 
                     θ 
                   
                   = 
                   
                     
                       
                         lim 
                         
                           d 
                           -&gt; 
                           ∞ 
                         
                       
                       ⁢ 
                       
                           
                       
                       ⁢ 
                       
                         
                           tan 
                           
                             - 
                             1 
                           
                         
                         ⁢ 
                         
                           
                             
                               4 
                               ⁢ 
                               D 
                             
                             + 
                             
                               4 
                               ⁢ 
                               H 
                             
                           
                           L 
                         
                       
                     
                     = 
                     
                       π 
                       2 
                     
                   
                 
               
             
           
         
       
     
     Accordingly, the irradiation angle θ of the ion beam is expressed by the equation below: 
     
       
         
           
             
               
                 
                   
                     
                       tan 
                       
                         - 
                         1 
                       
                     
                     ⁢ 
                     
                       
                         4 
                         ⁢ 
                         D 
                       
                       L 
                     
                   
                   ≤ 
                   θ 
                   ≤ 
                   
                     
                       π 
                       2 
                     
                     ⁢ 
                     
                         
                     
                     ⁢ 
                     or 
                   
                 
               
             
             
               
                 
                   
                       
                   
                   ⁢ 
                   
                     
                       
                         tan 
                         
                           - 
                           1 
                         
                       
                       ⁢ 
                       
                         
                           4 
                           ⁢ 
                           H 
                         
                         L 
                       
                     
                     ≤ 
                     θ 
                     ≤ 
                     
                       
                         π 
                         2 
                       
                       . 
                     
                   
                 
               
             
           
         
       
     
     In equation 4, 
     
       
         
           
             
               
                 lim 
                 
                   h 
                   -&gt; 
                   0 
                 
               
               ⁢ 
               
                 W 
                 ⁢ 
                 
                     
                 
                 ⁢ 
                 1 
               
             
             = 
             
               
                 
                   lim 
                   
                     h 
                     -&gt; 
                     0 
                   
                 
                 ⁢ 
                 
                   [ 
                   
                     
                       L 
                       2 
                     
                     + 
                     
                       
                         L 
                         × 
                         D 
                       
                       
                         
                           4 
                           ⁢ 
                           D 
                         
                         + 
                         
                           4 
                           ⁢ 
                           H 
                         
                       
                     
                   
                   ] 
                 
               
               = 
               
                 
                   3 
                   4 
                 
                 ⁢ 
                 L 
               
             
           
         
       
       
         
           
             
               
                 lim 
                 
                   d 
                   -&gt; 
                   0 
                 
               
               ⁢ 
               
                 W 
                 ⁢ 
                 
                     
                 
                 ⁢ 
                 1 
               
             
             = 
             
               
                 
                   lim 
                   
                     d 
                     -&gt; 
                     0 
                   
                 
                 ⁢ 
                 
                   [ 
                   
                     
                       L 
                       2 
                     
                     + 
                     
                       
                         L 
                         × 
                         D 
                       
                       
                         
                           4 
                           ⁢ 
                           D 
                         
                         + 
                         
                           4 
                           ⁢ 
                           H 
                         
                       
                     
                   
                   ] 
                 
               
               = 
               
                 L 
                 2 
               
             
           
         
       
       
         
           
             
               
                 lim 
                 
                   h 
                   -&gt; 
                   ∞ 
                 
               
               ⁢ 
               
                 W 
                 ⁢ 
                 
                     
                 
                 ⁢ 
                 1 
               
             
             = 
             
               
                 
                   lim 
                   
                     h 
                     -&gt; 
                     ∞ 
                   
                 
                 ⁢ 
                 
                   [ 
                   
                     
                       L 
                       2 
                     
                     + 
                     
                       
                         L 
                         × 
                         D 
                       
                       
                         
                           4 
                           ⁢ 
                           D 
                         
                         + 
                         
                           4 
                           ⁢ 
                           H 
                         
                       
                     
                   
                   ] 
                 
               
               = 
               
                 L 
                 2 
               
             
           
         
       
       
         
           
             
               
                 lim 
                 
                   d 
                   -&gt; 
                   ∞ 
                 
               
               ⁢ 
               
                 W 
                 ⁢ 
                 
                     
                 
                 ⁢ 
                 1 
               
             
             = 
             
               
                 
                   lim 
                   
                     d 
                     -&gt; 
                     ∞ 
                   
                 
                 ⁢ 
                 
                   [ 
                   
                     
                       L 
                       2 
                     
                     + 
                     
                       
                         L 
                         × 
                         D 
                       
                       
                         
                           4 
                           ⁢ 
                           D 
                         
                         + 
                         
                           4 
                           ⁢ 
                           H 
                         
                       
                     
                   
                   ] 
                 
               
               = 
               
                 
                   3 
                   4 
                 
                 ⁢ 
                 L 
               
             
           
         
       
     
     Hence, the width w 1  of the transmission part of the mask has a relationship of 
     
       
         
           
             
               L 
               2 
             
             ≤ 
             
               W 
               ⁢ 
               
                   
               
               ⁢ 
               1 
             
             ≤ 
             
               
                 3 
                 4 
               
               ⁢ 
               
                 L 
                 . 
               
             
           
         
       
     
       FIG. 5  is a flow diagram illustrating a method of forming a multi-domain alignment layer according to an embodiment of the present invention, and  FIGS. 6A through 6D  are sectional views schematically illustrating a method of forming a multi-domain alignment layer according to an embodiment of the present invention. 
     Referring to  FIG. 6A , a substrate  200  for an LCD is prepared and a mask  220   a  having predetermined patterns is arranged spaced apart from the substrate  200  by a predetermined interval (S 100 ). 
     The substrate  200  has TFTs or color filters formed thereon. 
     A tilt angle of liquid crystal molecule is determined by inclining the substrate  200  with respect to an irradiated ion beam by a predetermined angle. 
     Then, an alignment layer  210  is formed on the substrate  200 . 
     At this time, the mask  220   a  has predetermined slit pattern that is formed corresponding to multi-divided areas with respect to a unit pixel of the substrate  200 . The mask  220   a  is arranged spaced apart from the substrate  200  by a predetermined interval. 
     Referring to  FIG. 6B , the substrate  200  is loaded on an ion beam irradiation apparatus, and a primary ion beam  230  is irradiated onto the substrate  200  (S 110 ). 
     The irradiated ion beam  230  passes through the mask  220   a  having the slit pattern and reach the substrate  200 . Thus, the alignment layer  210  exposed to the ion beams  230  is aligned in a predetermined direction. 
     Meanwhile, when the alignment layer  210  formed of organic material such as polyimide is formed on the substrate  200 , the polyimide is divided into a main chain and a side chain in view of a chemical structure. The main chain functions to align liquid crystal molecules in a single alignment direction and the side chain functions to form a tilt angle. 
     The alignment layer  210  may be formed of an inorganic material such as SiO 2 , SiC, Si 3 N 4 , Al 2 O 3 , CeO 2 , SnO 2 , glass, ZnTiO 2 , diamond-like carbon (DLC), or the like. 
     The mask  220   a  includes the slit pattern that has a predetermined transmission part and a predetermined shielding part. In the mask  220   a  constructed as above, the alignment layer  210  is aligned on only some divided areas of the pixel cell due to the ion beams  230 , which pass through the slit of the mask  220   a.    
     Then, the irradiated primary ion beam  230  is shielded and the substrate  200  is then rotated (S 120 ). 
     Here, the substrate  200  may be rotated up and down. 
     Referring to  FIG. 6C , the substrate  200  inclined with respect to the irradiated ion beams  230  is arranged inclined in an opposite direction. 
     At this time, a mask  220   b  that is arranged spaced apart from the substrate  200  is re-arranged (S 130 ). 
     The mask  220   b  has a slit pattern and may shield a secondary ion beam that is irradiated on the areas aligned due to the primary ion beam at the alignment layer  210 . 
     Here, the mask  220   a  used in the irradiation of the primary ion beams may be used as the mask  220   b  by shifting the mask  220   a . Also, as the mask  220   b , another mask may be used by spacing it apart from the substrate  200  and re-arranging it. 
     Referring to  FIG. 6D , the substrate  200  is re-arranged in the above manner and secondary ion beams  230  are irradiated (S 140 ). 
     The irradiated secondary ion beam  230  passes through the mask  220   b  having the slit pattern and reach the substrate  200 . Thus, the alignment layer  210  exposed to the secondary ion beam  230  is aligned in a predetermined direction. 
     Here, the ion beams  230  passing through the slit of the mask  220   b  cause only some divided areas of the unit pixel to be aligned in a direction opposite to an alignment direction formed in the irradiation of the primary ion beam. 
     In other words, the alignment direction formed by irradiating the primary ion beam onto the alignment layer  210  is opposite to that formed by irradiating the secondary ion beam. 
     In this manner, it is possible to perform the multi alignment process within each unit pixel of the substrate  200  by irradiating the primary ion beam  230  onto the alignment layer  210 , rotating the substrate  200  and then irradiating the secondary ion beam  230 . 
     According to the method of forming a multi-domain alignment layer through the irradiation of ion beams on the alignment layer in the LCD, the mask having an appropriate thickness, transmission part and shielding part is arranged at a front of the alignment layer. Then, relations among width of the transmission part of the mask, pixel size, thickness of the mask, distance between the alignment layer and the mask, and ion beam irradiation angle are provided. Thus, the multi-alignment process may be performed effectively, thereby simplifying the manufacturing process and reducing the manufacturing cost. 
     It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention. 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.