Abstract:
The present invention provides 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 rigid substrate or flexible substrate provided with a master pattern, providing a base roller arranged on the substrate provided with the master pattern, forming a mold surface layer on the substrate provided with the master pattern, forming an adhesive resin layer on the mold surface layer or the base roller, rolling the base roller over the rigid substrate or flexible substrate to form the adhesive resin layer and the mold surface layer on the base roller, and curing the adhesive resin layer and mold surface layer formed on the base roller to adhere the adhesive resin layer and the mold surface layer to the base roller and fix the same thereon.

Description:
This application claims the benefit of Korean Patent Application No. P2010-0016413, filed on Feb. 23, 2010 and Korean Patent Application No. P2010-0030432, filed on Apr. 2, 2010, which is hereby incorporated by reference as if fully set forth herein. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     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. 
     2. Discussion of the Related Art 
     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. 
     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  illustrated in  FIG. 1A  is underway. 
     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 on the surface of the base roller  14  and a mask pattern are sequentially formed, the etch-protecting layer is patterned by 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 . 
     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. 
     In order to solve these problems, as shown in  FIG. 1B , a method of adhering a flat panel mold  22 , obtained by forming a pattern layer  20  on a flexible substrate  18 , to a base roller  16  has been suggested. However, during adhesion of the base roller  16  to the flat panel mold  22 , misalignment often occurs, disadvantageously causing dimensional error. 
     SUMMARY OF THE INVENTION 
     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. 
     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 mold and simplify the overall manufacturing process. 
     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 rigid substrate or flexible substrate provided with a master pattern; providing a base roller arranged on the substrate provided with the master pattern; forming a mold surface layer on the substrate provided with the master pattern; forming an adhesive resin layer on the mold surface layer or the base roller; rotating the base roller on the rigid substrate or flexible substrate to form the adhesive resin layer and the mold surface layer on the base roller; and curing the adhesive resin layer and mold surface layer formed on the base roller to adhere the adhesive resin layer and the mold surface layer to the base roller and fix the same thereon. 
     The step of providing the rigid substrate or flexible substrate provided with the master pattern may include forming a master pattern layer including a protrusion pattern and a groove pattern to provide the master pattern on the rigid substrate or flexible substrate having a flat surface, wherein the master pattern layer is made of an organic material which can be stripped, wherein the mold surface layer is made of diamond like carbon (DLC), silicon oxide (SiO 2 ) or indium tin oxide (ITO), wherein the adhesive resin layer is a thermocurable or photocurable adhesive. 
     The method may further include: forming an anti-adhesion layer between the mold surface layer and the master pattern layer. 
     The method may further include: removing the master pattern layer remaining on the mold surface layer through a stripping process, after adhering the adhesive resin layer and the mold surface layer to the base roller and fixing the same thereon. 
     The step of rolling the base roller on the rigid substrate or flexible substrate may be carried out by rolling the base roller on the flexible substrate, while adhering one end of the flexible substrate to a un-winder and adhering another end of the flexible substrate to a re-winder, and keeping the flexible substrate level. 
     In accordance with another aspect of the present invention, provided is a method for fabricating a roll mold including: providing a rigid substrate or flexible substrate provided with a master pattern; providing a base roller arranged on the substrate provided with the master pattern; forming an adhesive resin layer on the substrate provided with the master pattern; rotating the base roller on the rigid substrate or flexible substrate to transcribe the adhesive resin layer onto the base roller; forming a mold surface layer on the adhesive resin layer; and curing the adhesive resin layer and the mold surface layer formed on the base roller to adhere the adhesive resin layer and the mold surface layer to fix the same on the base roller. 
     The step of providing the rigid substrate or flexible substrate provided with the master pattern may include forming a master pattern including a protrusion pattern and a groove pattern to provide the master pattern on the rigid substrate or flexible substrate having a flat surface, wherein the master pattern layer is made of an organic material which can be stripped, wherein the mold surface layer is made of diamond like carbon (DLC), silicon oxide (SiO 2 ) or indium tin oxide (ITO), and wherein the adhesive resin layer is a thermocurable or photocurable adhesive. 
     In accordance with another aspect of the present invention, provided is a roll mold including: a base roller; an adhesive resin layer formed on the base roller; and a mold surface layer formed between and on the adhesive resin layer. 
     In accordance with another aspect of the present invention, provided is a method for fabricating a thin film pattern, including: providing a roll mold including a base roller, an adhesive resin layer formed on the base roller, and a mold surface layer formed on the adhesive resin layer and the adhesive resin layer; forming a printing liquid on the roll mold or substrate; and rolling the roll mold on the substrate to form a thin film pattern on the substrate. 
     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 along with the description serve to explain the principle of the invention. In the drawings: 
         FIGS. 1A and 1B  are sectional views illustrating a conventional roll mold; 
         FIG. 2  is a perspective view illustrating a printing or imprinting device for forming a thin film pattern according to the present invention; 
         FIGS. 3A to 3C  are sectional views illustrating a method for fabricating the roll mold illustrated in  FIG. 2  according to a first embodiment; 
         FIGS. 4A to 4C  are sectional views illustrating a method for fabricating the roll mold illustrated in  FIG. 2  according to a second embodiment; 
         FIGS. 5A to 5C  are sectional views illustrating a method for fabricating the roll mold illustrated in  FIG. 2  according to a third embodiment; 
         FIG. 6  is a sectional view illustrating an anti-adhesion layer formed between the master pattern layer and the mold surface layer shown in  FIGS. 3B ,  4 B and  5 A; 
         FIGS. 7A to 7C  are views illustrating a method for fabricating a thin film pattern via an imprinting method employing a roll mold according to a first embodiment; 
         FIGS. 8A to 8C  are views illustrating a method for fabricating a thin film pattern via a printing method employing a roll mold according to a second embodiment; 
         FIGS. 9A to 9D  are views illustrating a method for fabricating a thin film pattern via a printing method employing a roll mold according to a third embodiment; and 
         FIG. 10  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 
     Hereinafter, the present invention will be described with reference to the annexed drawings. 
       FIG. 2  is a perspective view illustrating a printing or imprinting device for forming a thin film pattern according to the present invention. 
     The printing or imprinting device in  FIG. 2  includes a printing liquid supplier  120  and a roll mold  140 . 
     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. 
     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  is moved and comes into contact with the substrate  101 , while the substrate  101  is fixed. 
     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 . 
     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. 
     Such a roll mold  140  includes a base roller  144 , an adhesive resin layer  142  and a mold surface layer  146 . 
     The adhesive resin layer  142  adheres the base roller  144  to the mold surface layer  146 . In addition, the adhesive resin layer  142  offsets stress applied from the roll mold  140  to the substrate  101 , when the roll mold  140  is rolled over the substrate  101 , and offsets stress applied from the base roller  144  to the rigid substrate or flexible substrate, when the base roller  144  is rolled over the rigid substrate or flexible substrate in the process of forming the roll mold  140  described below. The adhesive resin layer  142  is made of a UV-curable or thermocurable adhesive such as a sealant provided between the base roller  144  and the mold surface layer  146 . 
     The mold surface layer  146  is made of a hydrophobic material such as diamond like carbon (DLC), silicon oxide (SiO2) or indium tin oxide (ITO) which exhibits high durability, superior mechanical properties and a release (detachment) property. The mold surface layer  146  is formed on the adhesive resin layer  142  and the base roller  144  such that it has a groove  148  having the same shape as the pattern to be formed on the substrate  101 , or the inverse thereof. 
       FIGS. 3A to 3C  are sectional views illustrating a method for fabricating the roll mold illustrated in  FIG. 2  according to a first embodiment. 
     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 flat rigid substrate  110 . 
     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 rigid substrate  110  are separately formed, or a master pattern having a groove pattern and a protrusion pattern on the rigid substrate  110  by patterning the rigid substrate  110  may be formed. 
     Then, the mold surface layer  146  is formed on the master pattern layer  112  along the protrusion pattern  112   b  and the groove pattern  112   a  of the mask pattern layer  112 . The mold surface layer  146  is made of a hydrophobic material such as diamond like carbon (DLC), silicon oxide (SiO 2 ) or indium tin oxide (ITO) which exhibits high durability, superior mechanical properties and a release (detachment) property. 
     A base roller  144  to which the adhesive resin layer  142  is applied is provided on the mold surface layer  146 . Meanwhile, the adhesive resin layer  142  may be formed on the mold surface layer  146 , instead of on the base roller  144 . The adhesive resin layer  142  is made of a UV-curable or thermocurable adhesive such as a sealant. 
     As shown in  FIG. 3B , a base roller  144  provided with the adhesive resin layer  142  is rolled over the rigid substrate  110  provided with the mold surface layer  146 . Based on the pressure applied when the base roller  144  is rolled over the rigid substrate  110 , the mold surface layer  146  corresponding to the protrusion pattern  112   b  of the master pattern layer  112  is formed on the base roller  144  such that it comes into contact with the base roller  144 , and the mold surface layer  146  corresponding to the groove pattern  112   a  of the master pattern layer  112  is formed on the adhesive resin layer  142 . Accordingly, based on the pressure formed by rotation of the base roller  144 , the mold surface layer  146  corresponding to the protrusion pattern  112   b  of the master pattern layer  112  is formed on the base roller  144  such that it comes in contact with the base roller  144 , and the mold surface layer  146  corresponding to the groove pattern  112   a  of the master pattern layer  112  is formed on the adhesive resin layer  142 . 
     Then, the adhesive resin layer  142  is cured by UV irradiation or heating. As a result, the mold surface layer  146  and the adhesive resin layer  142  provided on the base roller  144  are cured and thus adhered to and fixed on the base roller  144 . 
     Accordingly, as shown in  FIG. 3C , the mold surface layer  146  is formed between and on the adhesive resin layers  142 , to complete a roll mold  140  having a groove  148  corresponding to a region between the adhesive resin layers  142 . 
       FIGS. 4A to 4C  are sectional views illustrating a method for fabricating the roll mold illustrated in  FIG. 2  according to a second embodiment. 
     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 flat rigid substrate  110 . The master pattern layer  112  is formed by applying an organic material, which can be stripped, such as photoresist, and patterning the material using a process such as photolithography, holographic lithography, laser processing, electron beam processing, focused ion beam processing or the like. Then, the mold surface layer  146  is formed on the master pattern layer  112  along the protrusion pattern  112   b  and the groove pattern  112   a  of the mask pattern layer  112 . The mold surface layer  146  is made of a hydrophobic material such as diamond like carbon (DLC), silicon oxide (SiO 2 ) or indium tin oxide (ITO) which exhibits high durability, superior mechanical properties and a release (detachment) property. 
     A base roller  144 , to which the adhesive resin layer  142  is applied, is provided on the mold surface layer  146 . Meanwhile, the adhesive resin layer  142  may be formed on the mold surface layer  146 , instead of on the base roller  144 . The adhesive resin layer  142  is made of a UV-curable or thermocurable adhesive such as a sealant. 
     As shown in  FIG. 4B , both ends of the flexible substrate  110  provided with the mold surface layer  146  are rolled on a re-winder  118  and an un-winder  116 , thereby keeping the flexible substrate  110  level. That is, one end of the flexible substrate  110  is adhered to the un-winder  116  and the other end of the flexible substrate  110  is adhered to the re-winder  118 . At this time, the master pattern layer  112  and the mold surface layer  146  may be formed or not formed on both ends of the flexible substrate  110  rolled on the re-winder  118  and un-winder  116 . 
     Next, the base roller  144  provided with the adhesive resin layer  142  is rolled over the flexible substrate  110  provided with the mold surface layer  146 . Accordingly, the mold surface layer  146  is transcribed on and adhered to the adhesive resin layer  142 . At this time, based on the pressure applied when the base roller  144  is rolled over the mold surface layer  146 , the mold surface layer  146  corresponding to the protrusion pattern  112   b  of the master pattern layer  112  is formed on the base roller  144  such that it comes into contact with the base roller  144 , and the mold surface layer  146  corresponding to the groove pattern  112   a  of the master pattern layer  112  is formed on the adhesive resin layer  142 . 
     Then, the adhesive resin layer  142  is cured by UV irradiation or heating. As a result, the mold surface layer  146  and the adhesive resin layer  142  provided on the base roller  144  are cured and thus adhered to and fixed on the base roller  144 . 
     Accordingly, as shown in  FIG. 4C , the mold surface layer  146  is formed between and on the adhesive resin layers  142 , to complete a roll mold  140  having a groove  148  corresponding to a region between the adhesive resin layers  142 . 
       FIGS. 5A to 5C  are sectional views illustrating a method for fabricating the roll mold illustrated in  FIG. 2  according to a third embodiment. 
     As shown in  FIG. 5A , a master pattern layer  112  having a groove pattern  112   a  and a protrusion pattern  112   b  is formed on a rigid or flexible substrate  110 . The master pattern layer  112  is formed by applying an organic material, which can be stripped, such as a photoresist, and patterning the material using a process such as photolithography, holographic lithography, laser processing, electron beam processing, focused ion beam processing or the like. Then, an adhesive resin layer  142  is formed on the master pattern layer  112 . The adhesive resin layer  142  is made of a UV-curable or thermocurable adhesive such as a sealant. 
     Then, the base roller  144  is rolled over the flexible substrate  110  provided with the adhesive resin layer  142 . Accordingly, the adhesive resin layer  142  is transcribed to the base roller  144  and is thus formed on the base roller  144 , as shown in  FIG. 5B . 
     A mold surface layer  146  is formed on the base roller  144  provided with the adhesive resin layer  142  by sputtering or PECVD, as shown in  FIG. 5C . The mold surface layer  146  is made of a hydrophobic material such as diamond like carbon (DLC), silicon oxide (SiO 2 ) or indium tin oxide (ITO) which exhibits high durability, superior mechanical properties and a release (detachment) property. The mold surface layer  146  is formed between and on the adhesive resin layers  142 , to complete a roll mold  140  in which a groove  148  is provided in a region provided between the adjacent two adhesive resin layers  142 . 
     Meanwhile, the master pattern layer  112  is subjected to anti-adhesion treatment, as shown in  FIGS. 3B ,  4 B and  5 A, or an anti-adhesion layer  122  may be formed between the mold surface layer  146  (or adhesive resin layer  142 ) and the master pattern layer  112 , as shown in  FIG. 6 . 
     The anti-adhesion layer  122  prevents adhesion of the master pattern layer  112  to the roll mold  140  along the mold surface layer  146  or adhesive resin layer  142 , when the master pattern layer  112  and the mold surface layer  146  (in  FIGS. 3B and 4A , or adhesive resin layer  142  in  FIG. 5A ) are released or detached. The anti-adhesion layer  122  is made of FOTS (fluoro-octyl-trichloro-silane) or HDFS ((heptadecafluoro-1,1,2,3-tetrahydrodecyl)trichlorosilane). 
     In addition to the anti-adhesion treatment or formation of anti-adhesion layer, the master pattern layer  112  may be formed of a hydrophobic material and the base roller  144  may be formed of a hydrophilic material, to improve release of the roll mold  140 . 
     In addition, when the master pattern layer  112  is adhered to the roll mold  140  along the mold surface layer  146  or adhesive resin layer  142 , the master pattern layer  112  is removed from the roll mold  140  by a stripping process. 
     As shown in  FIGS. 7A to 7C  are views illustrating a method for patterning a thin film via an imprinting method employing a roll mold according to a first embodiment. 
     In  FIG. 7A , a printing liquid  130  is applied to a substrate  101  through a printing liquid supplier  120 . Then, as shown in  FIG. 7B , a roll mold  140  including a base roller  144 , an adhesive resin layer  142  and a master pattern layer  146  is aligned. The roll mold  140  is rolled over the substrate  101 . At this time, a printing liquid  130  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. 7C , the printing liquid  130  is formed in the form of a thin film pattern on the substrate  101 . 
       FIGS. 8A to 8C  are views illustrating a method for patterning a thin film via a printing method employing a roll mold according to a second embodiment. 
     As shown in  FIG. 8A , a roll mold  140  including a base roller  144 , an adhesive resin layer  142  and a master pattern layer  146  is provided. The printing liquid  130  is filled through the printing liquid supplier  120  in the groove  148  of the roll mold  140 . 
     Then, as shown in  FIG. 8B , the roll mold  140 , filled with the printing liquid  130 , is rolled over the substrate  101 . Accordingly, the printing liquid  130  is transcribed, dried and cured on the substrate  101  and is thus formed into a thin film pattern, as shown in  FIG. 8C . 
       FIGS. 9A to 9D  are views illustrating a method for patterning a thin film via a printing method employing a roll mold according to a third embodiment. 
     As shown in  FIG. 9A , a roll mold  140  including a base roller  144 , an adhesive resin layer  142  and a master pattern layer  146  is provided. A printing liquid  130 , supplied through the printing liquid supplier  120 , fills the groove  148  of the roll mold  140 . 
     Then, as shown in  FIG. 9B , the printing liquid  130  is transcribed to a transcription roller  132 , which rotates, and, at the same time, is engaged in the roll mold  140 . The roll mold  140  provided with the printing liquid  130  is rolled over the substrate  101 . Accordingly, the printing liquid  130  is transcribed, dried and cured on the substrate  101  and is thus formed into a thin film pattern, as shown in  FIG. 9D . 
     Specifically, a liquid crystal display panel according to the present invention, as shown in  FIG. 10 , includes a thin film transistor substrate  150  and a color filter substrate  180  such that the liquid crystal layer  160  is interposed between the thin film transistor substrate  150  and the color filter substrate  180 . 
     The color filter substrate  180  includes a black matrix  184 , a color filter  186 , a common electrode  188 , and a column spacer (not shown) arranged on an upper substrate  182  in this order. 
     The thin film transistor substrate  150  includes a plurality of gate lines  156  and a plurality of data lines  154  which cross each other on a lower substrate  152 , a thin film transistor  158  adjacent to each intersection between the gate lines  156  and the data lines  154 , and a pixel electrode  170  formed at a pixel region provided by the intersection. 
     An organic pattern used as a mask for patterning a thin film pattern made of an organic material such as the color filter  186 , the black matrix  184  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. 
     In addition, the roll mold according to the present invention 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. 
     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, the roll mold, a method for fabricating the same, and a method for fabricating a thin film pattern using the same according to the present invention can secure mechanical properties, durability and release of a roll mold, since a mold surface layer (the uppermost layer of the roll mold) is made of a hard and hydrophobic material. In addition, the present invention can obtain offset effects upon roll imprinting, since a soft adhesive resin layer is formed between a mold surface layer made of a hard material and a base roller made of a hard material. In addition, the present invention can offset deformation of substrate caused by tension, pressure and heat in a roll-to-roll imprinting process when the base roller is rolled over a rigid substrate or flexible substrate. Accordingly, the present invention can maintain the size of master pattern layer even after fabrication of the roll mold. 
     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.