Abstract:
A fabrication apparatus and method use a mold for forming a pattern. The fabrication may be related to a thin film transistor (TFT) used for a switching element and a driving element in a display device, such as a liquid crystal display (LCD) or organic electroluminescent display (OELD). The fabrication method and apparatus fabricate a soft mold using a resin layer that is attached to a back plane in substantially a vacuum environment. The resin layer may be irradiated with ultraviolet (UV) light and then detached from a master plate to form a desired pattern. The fabrication process is such that the soft mold is relatively thin and light-weight, but resistant to being damaged.

Description:
[0001]    The present application claims the benefit of Korean Patent Application 2006-0053127 filed in Korea on Jun. 13, 2006, which is hereby incorporated by reference. This application is related to the patent application entitled “SOFT MOLD AND METHOD OF FABRICATING THE SAME,” (Atty. Dkt. No. 12576/7080 {F07-0088}), Ser. No. ______, filed on ______. 
     
     BACKGROUND 
       [0002]    1. Field of the Disclosure 
         [0003]    The present disclosure relates to a mold for forming a pattern, and more particularly to a fabrication apparatus and a method for fabricating a soft mold. 
         [0004]    2. Discussion of the Related Art 
         [0005]    Generally, a thin film transistor (TFT) is used for a switching element and a driving element of a liquid crystal display (LCD) device and an organic electroluminescent display (OELD) device. A fabricating method of the TFT is explained with reference to  FIGS. 1A to 1G .  FIGS. 1A to 1G  are cross-sectional views showing a fabricating process of a TFT according to the related art. 
         [0006]      FIGS. 1A and 1B  show a first mask process. As shown in  FIG. 1A , a first metal layer  12  is formed on a substrate  10  by depositing a first metallic material. The first metallic material may include one of aluminum (AL) or aluminum alloy (AlNd). A first photoresist (PR) layer  14  is formed on the first metal layer  12  by coating a PR material. The PR material may be categorized as either a positive type or a negative type. In the positive type, an irradiated portion of the PR layer is removed by a developing process exposing the PR layer. Contrary to the positive type, an irradiated portion of the PR layer remains after the developing process in the negative type. As shown, the positive type PR material is used. A first mask M having a transmitting portion A and a blocking portion B is disposed over the first PR layer  14 , and the first PR layer  14  is exposed to light through the first mask M. The transmitting portion A has transmittance greater than that of the blocking portion B. For example, the transmittance of the transmitting portion A is about 100%, and the transmittance of the blocking portion B is about 0%. 
         [0007]    The PR layer  14  is then developed, and an exposed portion of the first PR layer  14  is removed to form a first PR pattern  16  on the first metal layer  12 . The first metal layer  12  except for a portion under the first PR pattern  16  is exposed. As shown in  FIG. 1C , the exposed first metal layer  12  is etched using the first PR pattern  16  as an etching mask to form a gate electrode  18  on the substrate  10 . After the first PR pattern  16  is removed, a gate insulating layer  20  is formed on entire surface of the substrate including the gate electrode  18 . 
         [0008]      FIG. 1D  shows a second mask process. An intrinsic amorphous silicon layer (not shown) and an impurity-doped amorphous silicon layer (not shown) are sequentially formed on the gate insulating layer  20 . The intrinsic amorphous silicon layer (not shown) and the impurity-doped amorphous silicon layer (not shown) are patterned using a second mask (not shown) as a patterning mask to form an active layer  22  and an ohmic contact pattern  24  on the gate insulating material  20 . The active layer  22  and the ohmic contact pattern  24  correspond to the gate electrode  18 . The active layer  22  is formed of amorphous silicon (a—Si:H), and the ohmic contact pattern  24  is formed of impurities-doped amorphous silicon (n+a—Si:H). 
         [0009]      FIG. 1E  shows a third mask process. A second metal layer (not shown) is formed on the ohmic contact pattern  24 . The second metal layer may include one of aluminum (Al), aluminum alloy (AlNd), chromium (Cr), molybdenum (Mo), tungsten (W), titanium (Ti) and copper (Cu). The second metal layer (not shown) is etched using a third mask (not shown) as an etching mask to form a source electrode  26  and a drain electrode  28  on the ohmic contact pattern  24 . The source and drain electrodes  26  and  28  are separated from each other to expose the ohmic contact pattern  24  between the source and drain electrodes  26  and  28 . The ohmic contact pattern  24  between the source and drain electrode  28  is removed to form an ohmic contact layer  25  and expose the active layer  22  between the source and drain electrodes  26  and  28 . The active layer  22  that is exposed between the source and drain electrodes  26  and  28  is defined as a channel region. 
         [0010]      FIG. 1F  shows a fourth mask process. As shown in  FIG. 1F , a passivation layer  30  is formed on an entire surface of the substrate including the source and the drain electrodes  26  and  28 . The passivation layer  30  includes an inorganic insulating material, such as silicon oxide (SiO 2 ) or silicon nitride (SiNx), or includes an organic insulating material, such as benzocyclobutene (BCB) or an acryl resin. The passivation layer  30  is patterned using a fourth mask (not shown) as a patterning mask to form a drain contact hole  32  exposing the drain electrode  28 . 
         [0011]      FIG. 1G  shows a fifth mask process. A transparent conductive material layer (not shown) is formed on the passivation layer  30  and etched using a fifth mask (not shown) as an etching mask to form a pixel electrode  34 . The pixel electrode  34  contacts the drain electrode  28  through the drain contact hole  32 . The transparent conductive material layer may include indium-tin-oxide (ITO) or indium-zinc-oxide (IZO). 
         [0012]    The TFT and the pixel electrode connected thereto may be fabricated by the above-mentioned processes. As shown above, the fabricating process of the TFT requires several mask processes. The mask processes may include a step of coating the PR layer, a step of exposing the PR layer using a mask, a step of developing the PR layer, a step of removing the PR layer to form the PR pattern, a step of removing a material layer exposed by the PR pattern, and so on. Accordingly, production costs increase and production yields decrease due to the complicated mask processes. 
       SUMMARY 
       [0013]    In a first aspect, a method for fabricating a soft mold includes preparing a master plate including at least one pattern. A resin layer is disposed on the master plate over the at least one pattern. A back-plane is contacted with the resin layer in a substantially vacuum environment and the resin layer is cured. The resin layer is detached from the master plate. 
         [0014]    In a second aspect, a method for fabricating a soft mold includes providing a master plate with an embossed pattern and disposing a resin layer on the master plate over the embossed pattern. The master plate with the resin layer is inserted on a movable stage in a chamber. An adhesive material is applied on a back plane and the stage with the master plate is moved towards the back plane to contact the resin layer and the back plane with the adhesive material. The contact of the resin layer and the back plane occurs while the chamber has a substantially vacuum environment. The resin layer is cured and detached with the back plane from the master plate and the soft mold comprises the cured resin layer. 
         [0015]    In a third aspect, a fabrication apparatus includes a chamber and a back plane disposed in the chamber. A master plate is configured to fabricate a soft mold with a plurality of patterns. A stage within the chamber is configured to receive the master plate. A resin layer is disposed on the master plate. The stage is configured to allow the back plane to attach with the resin layer on the master plate while the chamber has a substantially vacuum environment. 
         [0016]    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. Other systems, methods, features and advantages will be, or will become, apparent to one with skill in the art upon examination of the following figures and detailed description. Nothing in this section should be taken as a limitation on those claims. Further aspects and advantages are discussed below in conjunction with the embodiments. Additional features and advantages of the embodiments will be set forth in the description which follows, and in part will be apparent from the description, or may be learned by practice of the invention. The objectives and other advantages of the invention will be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings. 
     
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0017]    The system and/or method may be better understood with reference to the following drawings and description. Non-limiting and non-exhaustive embodiments are described with reference to the following drawings. The components in the figures are not necessarily to scale, emphasis instead being placed upon illustrating the principles of the invention. In the figures, like referenced numerals designate corresponding parts throughout the different views. The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the principles of the invention. 
           [0018]      FIGS. 1A to 1G  are cross-sectional views showing a fabricating process of a thin film transistor (TFT) according to the related art. 
           [0019]      FIGS. 2A to 2D  are cross-sectional views showing a fabricating process of a soft mold according to one embodiment. 
           [0020]      FIG. 3  is a flow chart for explaining a fabricating process of a soft mold according to one embodiment. 
           [0021]      FIG. 4  is a schematic cross-sectional view showing an apparatus for fabricating a soft mold according to one embodiment. 
           [0022]      FIGS. 5A to 5F  are cross-sectional views illustrating a method of forming a pattern using a soft mold according to one embodiment. 
       
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
       [0023]    Reference will now be made in detail to the embodiments, examples of which are illustrated in the accompanying drawings. 
         [0024]      FIGS. 2A to 2D  are cross-sectional views showing a fabricating process of a soft mold according to one embodiment, and  FIG. 3  is a flow chart showing a fabricating process of a soft mold according to one embodiment. The soft mold is fabricated by coating a resin material layer on a master substrate, which having one of an embossed pattern and a depressed pattern, and hardening or curing the resin material layer using ultraviolet (UV) light. 
         [0025]    As shown in  FIG. 2A  and  FIG. 3 , a plurality of embossed patterns  102  are formed on the master plate  100  at block ST 1 . A plurality of depressed patterns instead of the plurality of embossed patterns  102  may be formed on the master plate  100 . The plurality of embossed patterns  102  may be formed of a same material as the master plate  100  or a different material from the master plate  100 . The master plate  100  is formed of silicon (Si), and the embossed patterns  102  are formed of one of Si, a metallic material, a PR material, wax, silicon nitride (Si 3 N 4 ) and silica (SiO 2 ). 
         [0026]    As shown in  FIG. 2B  and  FIG. 3 , a resin layer  110  is formed on the plurality of embossed patterns  102  at block ST 2 . The resin layer  110  is formed of a liquid phase polymer precursor having photo-curable properties. For example, the resin layer  110  may include polyurethane acrylate, glycidyl acrylate or butyl methacrylate. When glycidyl acrylate or butyl methacrylate is used, a photo-initiator, such as Irgacure  369  or Irgacure  819 , may be added. The resin layer  110  is formed on the master plate  100  using a spin coating method or a slit coating method. The thickness of the resin layer  110  may be modified depending on requirements for the mold. 
         [0027]    As shown in  FIG. 2C  and  FIG. 3 , the resin layer  110  is cured by irradiating UV light at block ST 3 . Since the resin layer  110  is cured by the UV light, damage on the resin layer  110  is minimized. Accordingly, the resin layer  110  may be formed to be thin because the resin layer is not deformed from the heat of a heat-curable process. Additionally, the UV curable resin has a relatively low viscosity, which allows for the resin layer  110  to have a relatively thin thickness. In addition, a heat curing process may take about one hour, while a UV curing process may take less than one minute. Generally, the lifetime of a UV cured mold is greater than the lifetime of a heat cured mold. 
         [0028]    As shown in  FIG. 2D  and  FIG. 3 , the resin layer  110  that is cured by the UV light is detached from the master plate  100  at block ST 4 . A back-plane  120  may be used for detaching the resin layer  110  from the master plate  100 . The back-plane  120  may be attached the resin layer  110  using adhesives (not shown). With the resin layer  110  attached to the back-plane  120 , the back-plane  120  may be detached from the master plate  100 . The resin layer  110  detached from the master plate  100  has a plurality of counter patterns  112  from the plurality of embossed patterns. The back-plane  120  may be formed of a transparent material, such as glass, quartz, polyethyleneterephthalate (PET), polymethylmethacrylated (PMMA), or polycarbonate (PC). In one example, the adhesive may be EC-2320 of 3M Co., Ltd. The adhesive may be formed on the back-plane  120  by a spray coating method, a spin coating method, a slit coating method or a bar coating method. As described, the fabricating process of the soft mold may be beneficially performed under a vacuum to prevent deterioration. 
         [0029]      FIG. 4  is a schematic cross-sectional view showing an apparatus for fabricating a soft mold according to one embodiment. The apparatus  200  for fabricating a soft mold includes a chamber  210  and a UV lamp  260 . The UV lamp  260  is disposed over the chamber  210 . A transparent window  250  is disposed near an upper wall of the chamber  210 . The transparent window  250  may be formed of glass or quartz, such that the UV light emitted from the UV lamp  260  may pass through the transparent window  250 . A stage  220  and a jig  230  are coupled with the chamber  210 . The master plate  100 , on which the resin layer  110  is formed, is disposed on the stage  220 . The stage  220  may be adjustable to move up and down or left and right relative to the chamber  210 . To move the stage  220 , a motor (not shown) may be disposed adjacent to the chamber  210  and configured to move the stage  220 . Accordingly, the master plate  100  on the stage can move up and down or right and left. The stage  220  includes a vacuum plate so that the master plate  100  may move without changing the position on the stage  220 . The jig  230  is disposed over the stage  220  and configured to receive the back-plane  120 . The back-plane  120  is disposed on or coupled with the jig  230 . The back-plane  120  may be fixed to the jig  230  by a fixing unit  240 . The jig  230  may also be adjustable and configured to move up and down. To move the jig  230 , a motor (not shown) may be formed adjacent to the chamber  210  and coupled with the jig  230 . Although not shown, the adhesives may be formed on the back-plane  120 . In addition, a camera may be disposed adjacent to the transparent window  250  to observe the chamber  210  and the process inside the chamber  210 . 
         [0030]    The apparatus as shown in  FIG. 4  may be used in a fabricating process of a soft mold. The master plate  100 , on which the resin layer  110  is disposed, is transported into the chamber  210  and disposed onto or adjacent the stage  220 . The inside of the chamber  210  may be substantially a vacuum. The master plate  100  is aligned with the back-plane  120  by moving the stage  220  left and right or forward and backward. As discussed above, the stage  220  includes a vacuum plate to stabilize the master plate  100  onto the stage  220 . Accordingly, the master plate  100  can move without altering the position on the stage  220 . The master plate  100  includes the plurality of embossed patterns  102  (of  FIG. 2A ) at a surface thereof. A surface of the resin layer  110  is embossed and depressed due to the plurality of embossed patterns  102 . 
         [0031]    The stage  220  may move upward, so that the back-plane  120  contacts the resin layer  110 . An adhesive (not shown) is formed on or disposed on a surface of the back-plane  120 . The surface of the back-plane  120  with the adhesive contacts the resin layer  110 , so that the back-plane  120  is attached to or coupled with the resin layer  110 . In one embodiment, the substantially vacuum condition may be maintained until after the soft mold and back plane  120  are detached from the master plate  100 . In another embodiment, the substantially vacuum condition may be removed after the surface of the back-plane  120  is contacted with the resin layer  110 . For example, the substantially vacuum condition may be removed with a blowing process using an inert gas, such as nitrogen or argon. The resin layer  110  may then be cured, such as through a heat curing process or an ultraviolet light curing process. As shown in the embodiment of  FIG. 2C , an ultraviolet light curing process is used. 
         [0032]    In the ultraviolet curing process, a UV lamp  260  emits UV light that is irradiated to the resin layer  110  through the transparent window  250  and through the back-plane  120  to cure the resin layer  110 . With the resin layer  110  attached to the back-plane  120 , the stage  220  moves downward, so that the resin layer  110  with the back-plane  120  is detached from the master plate  100 . In alternative embodiments, it is possible to move the back-plane  120  instead of the stage  220  to detach the resin layer  110 . 
         [0033]    Since the plurality of embossed patterns  102  (of  FIG. 2A ) are formed on the master plate  100 , the resin layer  110  detached from the master plate  100  has a plurality of counter patterns  112  (shown in  FIG. 2D ) from the plurality of embossed patterns  102 . After being detached, the resin layer  110  with the back-plane  120  may be transported into a chamber for the next process. The above-mentioned processes or parts of the above-mentioned process may be performed under a vacuum or an environment substantially similar to a vacuum in the chamber. 
         [0034]    A method of forming a pattern using the soft mold will be described hereinafter with reference to the accompanying drawings. In particular,  FIGS. 5A to 5E  are cross-sectional views illustrating the forming of a pattern using a soft mold according to one embodiment. 
         [0035]    In  FIG. 5A , a thin film  310  is formed on a substrate  300 , and a resist  320  is applied to the thin film  310 . The thin film  310  may be formed of a metallic material for electrodes of a thin film transistor (TFT), amorphous silicon material for an active layer or an ohmic contact layer of the TFT, or an insulating material, such as silicon nitride and silicon oxide. 
         [0036]    In  FIG. 5B , a soft mold  330 , which has depressed patterns  332  at a surface thereof may be developed. In one embodiment, the soft mold  330  may be developed as described above in  FIGS. 2-4 . Alternatively, the soft mold may be generated by other techniques. 
         [0037]    In  FIG. 5C , a soft mold  330 , which has depressed patterns  332  at a surface thereof, is disposed on the thin film  310  such that the depressed patterns  332  are adjacent to or face the thin film  310 . The soft mold  330  may have a hydrophobic property, and the resist  320  may have a hydrophilic property. The resist  320  is drawn into the depressed patterns  332  due to a repulsive force between the soft mold  330  and the resist  320 . A top surface of the soft mold  330  contacts the thin film  310 . 
         [0038]    In  FIG. 5D , the resist  320  in the depressed patterns  332  is cured by UV light to form resist patterns  322 . The soft mold  330  may be detached from the substrate  300  including the resist patterns  322  thereon. In  FIG. 5E , the thin film  310  of  FIG. 5C  is selectively etched using the resist patterns  322  as an etching mask to form desired patterns  312 . In  FIG. 5F , the resist patterns  322  are removed, leaving the desired patterns  312  on the substrate  300 . Accordingly, a thin film transistor (TFT) or an array substrate including the thin film transistors may be manufactured by performing the processes discussed above in  FIGS. 5A to 5F . 
         [0039]    As described, the soft mold is cured by UV light and is prevented from being transformed and damaged. Additionally, the soft mold may have relatively a thin thickness and light-weight. 
         [0040]    It will be apparent to those skilled in the art that various modifications and variations can be made in the fabrication apparatus for a soft mold and a method of fabricating a soft mold using the same of the present embodiments without departing from the spirit or scope of the invention. The illustrations of the embodiments described herein are intended to provide a general understanding of the structure of the various embodiments. The illustrations are not intended to serve as a complete description of all of the elements and features of apparatus and systems that utilize the structures or methods described herein. Many other embodiments may be apparent to those of skill in the art upon reviewing the disclosure. Other embodiments may be utilized and derived from the disclosure, such that structural and logical substitutions and changes may be made without departing from the scope of the disclosure. Additionally, the illustrations are merely representational and may not be drawn to scale. Certain proportions within the illustrations may be exaggerated, while other proportions may be minimized. Accordingly, the disclosure and the figures are to be regarded as illustrative rather than restrictive. The above disclosed subject matter is to be considered illustrative, and not restrictive, and the appended claims are intended to cover all such modifications, enhancements, and other embodiments, which fall within the true spirit and scope of the present invention.