Abstract:
Discussed are a roll mold, a method for fabricating the same and a method for fabricating a thin film pattern using the same, to prevent dimensional variation of the mold and simplify the overall process. The method for fabricating a roll mold includes providing a substrate provided with a master pattern layer, sequentially forming a mold surface layer and a solid suffer layer on the substrate provided with the master pattern layer to provide a flat panel mold, forming an adhesive resin layer on the base roller aligned on the flat panel mold, and rolling the base roller provided with the adhesive resin layer over the flat panel mold to adhere the flat panel mold to the base roller through the adhesive resin layer.

Description:
[0001]    This application claims the priority benefit of Korean Patent Application No. 10-2010-0078308, filed on Aug. 13, 2010, which is hereby incorporated by reference as if fully set forth herein. 
       BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The present invention relates to a roll mold, a method for fabricating the same and a method for fabricating a thin film pattern using the same. 
         [0004]    2. Discussion of the Related Art 
         [0005]    A variety of flat panel display devices to reduce weight and volume of the problems of cathode ray tubes have been introduced. Examples of flat panel display devices include liquid crystal display devices, field emission display devices, plasma display panel devices and electroluminescent (EL) display devices. 
         [0006]    Such a flat panel display device includes a plurality of thin films formed by a mask process including a series of deposition (coating), exposure to light, developing and etching processes. However, the mask process is complicated, thus disadvantageously increasing fabrication costs. Accordingly, recently, research into formation of thin films by an imprinting process using a roll mold  10 , as illustrated in  FIG. 1 , is underway. 
         [0007]    Such a roll mold  10  is formed by patterning the surface of a base roller  14  via an etching process. Specifically, an etch-protecting layer and a mask pattern are formed on the surface of the base roller  14 . Next, the etch-protecting layer is patterned through a primary etching process using the mask pattern as a mask. The surface of the base roller  14  is patterned by a secondary etching process using the patterned etch-protecting layer as a mask to obtain a roll mold  10  provided with a groove  12 . 
         [0008]    The roll mold  10  requires two etching processes, thus complicating the overall manufacturing process. The diameter of the base roller  14  is decreased through two etching processes, thus disadvantageously causing variation in the final size of the roll mold  10  and deformation thereof. 
       SUMMARY OF THE INVENTION 
       [0009]    Accordingly, the present invention is directed to a roll mold, a method for fabricating the same and a method for fabricating a thin film pattern using the same that substantially obviate one or more problems due to limitations and disadvantages of the related art. 
         [0010]    It is one object of the present invention to provide a roll mold, a method for fabricating the same and a method for fabricating a thin film pattern using the same, to prevent dimensional variation of the roll mold and simplify the overall manufacturing process. 
         [0011]    To achieve the object and other advantages and in accordance with the purpose of the invention, as embodied and broadly described herein, provided is a method for fabricating a roll mold including: providing a substrate provided with a master pattern layer; sequentially forming a mold surface layer and a solid buffer layer on the substrate provided with the master pattern layer to provide a flat panel mold; forming an adhesive resin layer on the base roller aligned on the flat panel mold; and rolling the base roller provided with the adhesive resin layer over the flat panel mold to adhere the flat panel mold to the base roller through the adhesive resin layer. 
         [0012]    The surface of the master pattern layer contacting the mold surface layer may be surface-treated with a hydrophobic material such as flurooctyl-trichloro-silane (FOTS) or (heptadecafluoro-1,1,2,3-tetrahydrodecyl)trichlorosilane (HDFS). 
         [0013]    In one embodiment, the step of providing the flat panel mold may include: forming the mold surface layer on the master pattern layer; forming the buffer layer on the mold surface layer, while one end of the flexible substrate is adhered to an unwinder and the other end of the flexible substrate is adhered to a rewinder and keeping the buffer layer level; rolling the base roller over the buffer layer and curing the mold surface layer using a light source arranged in the base roller; and cutting the buffer layer to a size of the mold surface layer, wherein the adhesion of the flat panel mold to the base roller through the adhesive resin layer further includes: curing the adhesive resin layer using the light source in the base roller. 
         [0014]    In another embodiment, the step of providing the flat panel mold may include: forming the mold surface layer on the master pattern layer; forming the buffer layer on the mold surface layer, while one end of the flexible substrate is adhered to an unwinder and the other end of the flexible substrate is adhered to a rewinder and keeping the buffer layer level; and cutting the buffer layer to a size of the mold surface layer, and wherein the adhesion of the flat panel mold to the base roller through the adhesive resin layer further includes: curing the mold surface layer and the adhesive resin layer using the light source arranged in the base roller. 
         [0015]    In accordance with another aspect of the present invention, provided is a roll mold including: a base roller provided with a light source; an adhesive resin layer formed on the base roller; a buffer layer formed on the adhesive resin layer; and a mold surface layer having a groove-protrusion shape formed on the buffer layer, wherein the mold surface layer and the adhesive resin layer are cured through light emitted from the light source arranged in the base roller. 
         [0016]    The mold surface layer may be made of a photocurable mold resin such as urethane-acrylate or polydimethylsiloxane, the buffer layer may be formed of a flexible substrate, and the adhesive resin layer may be made of a photocurable adhesive. 
         [0017]    In accordance with another aspect of the present invention, provided is an apparatus for fabricating a roll mold, including: a stage, on which a substrate provided with a master pattern layer is mounted; a first supply nozzle to apply a liquid mold surface layer onto the master pattern layer; an unwinder and a rewinder to fix both ends of the liquid buffer layer, such that the solid buffer layer is formed on the liquid mold surface layer, while maintaining the solid buffer layer level; a dicing unit to cut the buffer layer to the same size as the mold surface layer; and a second supply nozzle to apply a liquid mold surface layer onto the base roller rolling over the buffer layer. 
         [0018]    The apparatus may further include: a light source arranged in the base roller, the light source curing the liquid mold surface layer and the liquid adhesive resin layer; and a camera removably adhered to the base roller, to align the base roller on the buffer layer. 
         [0019]    In accordance with another aspect of the present invention, provided is a method for fabricating a thin film pattern, including: providing a roll mold comprising a base roller provided with a light source, an adhesive resin layer formed on the base roller, a buffer layer formed on the adhesive resin layer, and a mold surface layer having a groove-protrusion shape formed on the buffer layer; forming a printing liquid on the roll mold or the substrate; and rolling the roll mold over the substrate to form a thin film pattern on the substrate, wherein the mold surface layer and the adhesive resin layer are cured through light emitted from the light source arranged in the base roller. 
         [0020]    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 
         [0021]    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 along with the description serve to explain the principle of the invention. In the drawings: 
           [0022]      FIG. 1  is a sectional view illustrating a conventional roll mold; 
           [0023]      FIG. 2  is a perspective view illustrating a printing or imprinting device for forming a thin film pattern according to the present invention; 
           [0024]      FIGS. 3A to 3E  are sectional views illustrating a method for fabricating the roll mold illustrated in  FIG. 2  according to a first embodiment; 
           [0025]      FIGS. 4A to 4D  are sectional views illustrating a method for fabricating the roll mold shown in  FIG. 2  according to a second embodiment; 
           [0026]      FIGS. 5A to 5C  are views illustrating a method for patterning a thin film via an imprinting method employing the roll mold of the present invention according to a first embodiment; 
           [0027]      FIGS. 6A to 6C  are views illustrating a method for patterning a thin film via a printing method employing the roll mold of the present invention according to a second embodiment; 
           [0028]      FIGS. 7A to 7D  are views illustrating a method for patterning a thin film via a printing method employing the roll mold of the present invention according to a third embodiment; and 
           [0029]      FIG. 8  is a perspective view illustrating a liquid crystal display panel formed via the method of fabricating a thin film pattern according to the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0030]    Hereinafter, the present invention will be described with reference to the annexed drawings. 
         [0031]      FIG. 2  is a perspective view illustrating a printing or imprinting device for forming a thin film pattern according to the present invention. 
         [0032]    The printing or imprinting device in  FIG. 2  includes a printing liquid supplier  120  and a roll mold  140 . 
         [0033]    The printing liquid supplier  120  stores a printing liquid. The stored printing liquid is supplied to a roll mold  140  using a printing method, or supplied to a substrate  101  using an imprinting method in the process of patterning the thin film. 
         [0034]    The roll mold  140  rotates over a substrate  101  such that it contacts the substrate  101  conveyed by a conveyor  118 . Alternatively, the roll mold  140  may move so as to roll over the substrate  101  while the substrate  101  is fixed. 
         [0035]    A printing liquid from the printing liquid supplier  120  fills a groove  148  of the roll mold  140  by a printing method during the thin-film patterning process. The printing liquid in the groove  148  of the roll mold  140  is transcribed onto the substrate  101 , while the roll mold  140  is rolled over the substrate  101 . 
         [0036]    In addition, the roll mold  140  is rolled over the substrate  101 , to which the printing liquid is applied, using an imprinting method during the thin-film patterning, such that it comes into contact therewith. 
         [0037]    Such a roll mold  140  includes a base roller  144 , an adhesive resin layer  142 , a buffer layer  148  and a mold surface layer  146 . 
         [0038]    The mold surface layer  146  is made of a photocurable material such as urethane-acrylate or polydimethylsiloxane. The mold surface layer  146  is formed so as to have a groove and a protrusion having the same shape as the pattern to be formed on the substrate  101 , or the reverse shape thereof. 
         [0039]    The buffer layer  148  offsets stress applied from the roll mold to the substrate  101  when the roll mold  140  is rolled over the substrate  101  and comes into planar contact with the base roller  144  in the process of fabricating the roll mold  140 . 
         [0040]    The adhesive resin layer  142  adheres the base roller  144  to the buffer layer  148 . In addition, the adhesive resin layer  142  is formed of a photocurable adhesive such as a sealant between the base roller  144  and the buffer layer  148 . 
         [0041]    A light source  122 , as a curing apparatus to cure the mold surface layer  148  and the adhesive resin layer  142  is arranged in the base roller  144 . The light source  122  produces ultraviolet light and is surrounded by a light source housing (represented by reference numeral “ 124 ” in  FIG. 3C ). That is, the light source housing  124  surrounds the surface of the light source  122 , except for the surface of the light source  122  facing the stage. At this time, the light source  122  and the light source housing  124  do not rotate together the rotating base roller  144 , instead remaining stationary. 
         [0042]    In addition, a camera (represented by reference numeral “ 126 ” in  FIG. 3C ) to assist in aligning the base roller  144  is arranged in the base roller  144 . Specifically, the camera  126  aligns the base roller  144  when the base roller  144  is arranged on the buffer layer  148  and when the base roller  144 , to which the adhesive resin layer  142  has been applied, is arranged on the buffer layer  148 . The camera  126  is removably mounted in the base roller  144 , which is adhered in the process of alignment, and is detached after completion of alignment. 
         [0043]      FIGS. 3A to 3E  are sectional views illustrating a method for fabricating the roll mold illustrated in  FIG. 2  according to a first embodiment. 
         [0044]    As shown in  FIG. 3A , a master pattern layer  112  having a groove pattern  112   a  and a protrusion pattern  112   b  is formed on a master substrate  110  having a flat surface. The master pattern layer  112  is formed by applying an organic material, which can be stripped, such as photoresist, and patterning the material through photolithography, holographic lithography, laser processing, electron beam processing, focused ion beam processing or the like. Meanwhile, the master pattern layer  112  and the master substrate  110  are separately formed, or a master pattern whose surface has a groove pattern and a protrusion pattern may be formed by patterning the master substrate  110 . 
         [0045]    The master pattern layer  112  may be surface-treated with a self-assembled monolayer (SAM) to facilitate release (detachment) of the master pattern layer  112  from the mold surface layer  146 . Accordingly, adhesion of the masker pattern layer  112  to the roll mold  140  along the mold surface layer  146  can be prevented, when the master pattern layer  112  is released from the mold surface layer  146 . The self-assembled monolayer (SAM) is made of a hydrophobic material such as flurooctyl-trichloro-silane (FOTS) or (heptadecafluoro-1,1,2,3-tetrahydrodecyl)trichlorosilane (HDFS). 
         [0046]    Then, as shown in  FIG. 3B , a mold resin liquid is applied through a first supply nozzle  132  onto the master pattern layer  112  to form a mold surface layer  146 . A lower surface of the mold surface layer  146  which contacts the master pattern layer  112  is formed into a protrusion-groove shape along a protrusion  112   b  and a groove  112   a  of the mask pattern layer  112 . The mold surface layer  146  has a flat upper surface and is formed into a protrusion-groove shape along a protrusion  112   b  and a groove  112   a  of the mask pattern layer  112 . The mold surface layer  146  is made of a photocurable mold resin liquid such as urethane-acrylate or polydimethylsiloxane. 
         [0047]    Then, as shown in  FIG. 3C , the buffer layer  148 , which is rolled on a rewinder  118  and an unwinder  116  and thus maintains a parallel state, is aligned with the mold surface layer  146 . Then, both sides of the base roller  114  are aligned on the buffer layer  148  through an alignment key (not shown) and the camera  126  formed in at least one of a stage  130 , a master substrate  110 , a master pattern layer  112  and a mold pattern layer  146 . The camera  126  performs imaging to confirm whether an alignment key arranged at both sides of the base roller  144  corresponds to both sides of the base roller  144 , thus improving alignment accuracy. 
         [0048]    The base roller  144  aligned on the buffer layer  148  is rolled over the buffer layer  148 . Accordingly, printing pressure generated by the rotation of the base roller  144  is applied to the buffer layer  148  and tension is applied to the buffer layer  148  through the rewinder  118  and the unwinder  116 . In addition, the mold surface layer  146  is cured through the light source  122  arranged in the base roller  144  rotating on the buffer layer  148 . 
         [0049]    Meanwhile, the base roller  144  of the present invention is rolled over the buffer layer  148 , while the base roller  144  comes into planar contact with the solid buffer layer  148 . In this case, the base roller  144  does not slide on the cured solid buffer layer  148  and alignment accuracy between the buffer layer  148  and the base roller  144  is improved, thus improving pattern accuracy. In addition, the solid buffer layer  148  comes into planar contact with the base roller  144 , thus relatively increasing the contact area between the buffer layer  148  and the base roller  144 , and curing the mold surface layer  146  even with a low amount of light and in a relatively short period of time. 
         [0050]    On the other hand, a conventional base roller rotates while directly contacting a liquid mold surface layer without any buffer layer and coming into linear contact with the liquid mold surface layer. In this case, the base roller may slide on the uncured liquid mold surface layer, thus reducing alignment accuracy between the buffer layer and the base roller and reducing pattern accuracy. In addition, the liquid mold surface layer comes into linear contact with the base roller, thus relatively reducing the contact area between the buffer layer and the base roller and necessitating curing of the mold surface layer with a high amount of light for a relatively long time. 
         [0051]    Next, as shown in  FIG. 3D , the buffer layer  148  is cut to the same size as the mold surface layer  146  through a dicing process using a dicing unit (not shown) to obtain a flat panel mold including the mold surface layer  146  and buffer layer  148 . At the same time or after a while, the adhesive resin layer  142  is applied onto the base roller  144  through a second supply nozzle  134 . The adhesive resin layer  142  may be applied to the base roller  144  through the first supply nozzle  132  shown in  FIG. 3B , instead of through the second supply nozzle  134 . 
         [0052]    Next, as shown in  FIG. 3E , the base roller  144 , to which the adhesive resin layer  142  is applied, is rolled over the buffer layer  148 . At the same time, a light source  122  arranged in the base roller  144  is turned on and the adhesive resin layer  142  is cured through light emitted from the light source  122 . Accordingly, the flat panel mold including the mold surface layer  146  and the buffer layer  148  is adsorbed and fixed on the base roller  144  through the adhesive resin layer  142  to obtain a roll mold  140  having a groove and protrusion. 
         [0053]      FIGS. 4A to 4D  are sectional views illustrating a method for fabricating the roll mold shown in  FIG. 2  according to a second embodiment. This second embodiment is different from the first embodiment in that the mold surface layer  146  and the adhesive resin layer  142  are simultaneously cured. 
         [0054]    Specifically, as shown in  FIG. 4A , a master pattern layer  112  having a groove pattern  112   a  and a protrusion pattern  112   b  is formed on a master substrate  110  having a flat surface. The master pattern layer  112  having a groove pattern  112   a  and a protrusion pattern  112   b  is formed on a master substrate  110  having a flat surface. Next, as shown in  FIG. 4B , a mold resin liquid is applied onto the master pattern layer  112  through the first supply nozzle  132  to form a mold surface layer  146 . Next, as shown in  FIG. 4C , the buffer layer  148  which is rolled on a rewinder  118  and an unwinder  116 , and thus maintains a parallel state, is formed on the mold surface layer  146 . Next, the buffer layer  148  is cut to the same size as the mold surface layer  146  through a dicing process using a dicing unit (not shown) to obtain a flat panel mold including the mold surface layer  146  and buffer layer  148 . At the same time or after a while, the adhesive resin layer  142  is applied through the second supply nozzle  134  onto the base roller  144 . 
         [0055]    Next, as shown in  FIG. 4D , both sides of the base roller  114 , to which the adhesive resin layer  142  is applied, are aligned on the buffer layer  148  using an alignment key (not shown) and the camera  126  formed on at least one of a stage  130 , a master substrate  110 , a master pattern layer  112  and a mold pattern layer  146 . Next, a light source  122  arranged in the base roller  144  is turned on and the adhesive resin layer  142  is cured through light emitted from the light source  122 . Accordingly, the flat panel mold including the mold surface layer  146  and buffer layer  148  is adsorbed and fixed on the base roller  144  through the adhesive resin layer  142  to obtain a roll mold  140  having a groove and protrusion. 
         [0056]      FIGS. 5A to 5C  are views illustrating a method for patterning a thin film via an imprinting method employing the roll mold of the present invention according to a first embodiment. 
         [0057]    As shown in  FIG. 5A , a printing liquid  102  is applied to a substrate  101  through a printing liquid supplier  120 . Then, as shown in  FIG. 5B , a roll mold  140  including a base roller  144 , an adhesive resin layer  142 , a buffer layer  148  and a master pattern layer  146  is aligned on the substrate  101 . Next, the roll mold  140  is rolled over the substrate  101 . At this time, the printing liquid  102  is cured through a curing apparatus, such as a UV lamp, provided in the base roller  144  of the roll mold  140 , or a curing apparatus provided on the rear surface of the substrate  101 . As a result, as shown in  FIG. 5C , the printing liquid  130  is formed in the form of a thin film pattern  104  on the substrate  101 . 
         [0058]      FIGS. 6A to 6C  are views illustrating a method for patterning a thin film via a printing method employing the roll mold of the present invention according to a second embodiment. 
         [0059]    As shown in  FIG. 6A , a roll mold  140  including a base roller  144 , an adhesive resin layer  142 , a buffer layer  148  and a master pattern layer  146  is provided. The printing liquid  102  supplied from the printing liquid supplier  120  fills the groove of the roll mold  140 . 
         [0060]    Next, as shown in  FIG. 6B , the roll mold  140  filled with the printing liquid  102  is rolled over the substrate  101 . Accordingly, the printing liquid  102  is cured through a curing apparatus, such as a UV lamp, provided in the base roller  144  of the roll mold  140 , or a curing apparatus provided on the rear surface of the substrate  101 . Accordingly, the printing liquid  102  is transcribed, dried and cured on the substrate  101  and is thus formed into a thin film pattern, as shown in  FIG. 6C . 
         [0061]      FIGS. 7A to 7D  are views illustrating a method for patterning a thin film via a printing method employing the roll mold of the present invention according to a third embodiment. 
         [0062]    As shown in  FIG. 7A , a roll mold  140  including a base roller  144 , an adhesive resin layer  142 , a buffer layer  148  and a master pattern layer  146  is provided. The printing liquid  102  supplied by the printing liquid supplier  120  fills the groove of the roll mold  140 . 
         [0063]    Next, as shown in  FIG. 7B , the printing liquid  102  is transcribed to a transcription roller  106 , which rotates, and, at the same time, is engaged in the roll mold  140 . The transcription roller  106  provided with the printing liquid  102  is rolled over the substrate  101 , as shown in  FIG. 7C . Accordingly, the printing liquid  102  is transcribed, dried and cured on the substrate  101  and is thus formed into a thin film pattern, as shown in  FIG. 7D . 
         [0064]    As such, the thin film pattern  104  shown in  FIGS. 5C ,  6 C and  7 D may be used to form thin or thick films on flat panel display devices such as plasma display panels, electroluminescent (EL) display panels and field emission display devices as well as liquid crystal display panels. 
         [0065]    Specifically, the liquid crystal display panel according to the present invention shown in  FIG. 8  includes a thin film transistor substrate  180  and a color filter substrate  160  such that a liquid crystal layer  171  is interposed between the thin film transistor substrate  180  and the color filter substrate  160 . 
         [0066]    The color filter substrate  160  includes a black matrix  164 , a color filter  166 , a common electrode  168  and a column spacer (not shown) arranged on an upper substrate  162  in this order. 
         [0067]    The thin film transistor substrate  180  includes a plurality of gate lines  156  and a plurality of data lines  184  which cross each other on a lower substrate  182 , a thin film transistor  168  adjacent to each intersection between the gate lines  186  and the data lines  164 , and a pixel electrode  170  formed at a pixel region provided by the intersection. 
         [0068]    An organic pattern used as a mask for patterning a thin film pattern made of an organic material such as the color filter  166 , the black matrix  164  and the column spacer of the liquid crystal display panel and for patterning a thin film pattern made of an inorganic material such as the thin film transistor  188 , gate lines  186 , data lines  184  and pixel electrode  170  of the liquid crystal display panel may be formed by a printing process using the roll mold according to the present invention. 
         [0069]    The present invention forms a roll mold using application and transcription processes without using any conventional etching process, thus reducing fabrication process complexity and costs, and preventing dimensional variation of a roll mold caused by the etching process. In addition, a process for forming a flat panel mold and a process for adhering the flat panel mold to a base roller are performed in one apparatus in an inline manner. In addition, according to the present invention, the adhesive resin layer and the mold surface layer are cured by at least two light-exposure processes using a light source arranged in a base roller, thus reducing fabrication time and cost. In addition, according to the present invention, the base roller rotates and, at the same time, the flat panel mold is adhered to the base roller, thus increasing the thickness of the flat panel mold and pattern uniformity. In addition, according to the present invention, the roll mold is formed under the conditions of the same tension, roll pressure and heat as in a roll-to-roll imprinting process in which the roll mold rotates to form a thin film pattern, thus compensating for substrate deformation due to tension, pressure and heat in the roll-to-roll imprint process. 
         [0070]    It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the 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.