Abstract:
A stamp includes a transparent body having an inner chamber containing an inlet/outlet tube configured to have a fluid injected and removed therefrom.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the benefit of Korean Patent Application No. 10-2012-0006803, filed on Jan. 20, 2012, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein in its entirety by reference. 
       BACKGROUND 
       [0002]    1. Field 
         [0003]    The present disclosure relates to stamps, methods of fabricating the stamps, and imprint methods using the same. 
         [0004]    2. Description of the Related Art 
         [0005]    Nanoimprint lithography (NIL) is a technology of pressing a stamp onto an imprint resist layer of a substrate to transfer a nano-pattern formed on a surface of the stamp to the imprint resist layer. In NIL, the nano-pattern is formed due to a direct contact between the stamp and the imprint resist layer. NIL is divided into thermal NIL and ultraviolet (UV)-curable NIL according to external energy used to form a pattern. A representative example of UV-curable NIL is step and flash imprint lithography (S-FIL). S-FIL is a technology of coating a UV-curable liquid imprint resin on a substrate, pressing a transparent stamp onto the imprint resin, and curing the imprint resin by using UV rays, thereby performing an imprint process. 
         [0006]    Productivity, uniformity, and accuracy of S-FIL depends on various factors. For instance, how well a resin is coated, spread into a pattern, cured, aligned, uniformly pressed, etc. To improve these various factors, development of a resin and components of an NIL system is required. 
       SUMMARY 
       [0007]    Provided is a stamp, methods of fabricating the stamp, and imprint methods using the same. 
         [0008]    Additional aspects will be set forth in part in the description which follows and, in part, will be apparent from the description, or may be learned by practice of the presented embodiments. 
         [0009]    According to an example embodiment, a stamp includes a transparent body having an inner chamber containing an inlet/outlet tube configured to have a fluid injected and removed therefrom. 
         [0010]    The transparent body may be formed of a material capable of being internally processed by using a laser to form the inner chamber and the inlet/outlet tube on the inside of the transparent body. 
         [0011]    The transparent body may be formed of quartz. 
         [0012]    The inner chamber may have a shape in which at least a portion of a surface of the inner chamber is one of flat, convex, and concave, if the fluid is not injected. 
         [0013]    The inner chamber may have a circular or polygonal shape. 
         [0014]    The stamp may be configured for use in a nanoimprint process. 
         [0015]    According to another example embodiment, a method of fabricating a stamp includes internally processing a transparent body by using a laser to form an inner chamber in the transparent body; and forming in the transparent body an inlet/outlet tube configured to have a fluid injected and removed therefrom. 
         [0016]    The internal processing may be performed by using a femtosecond laser. 
         [0017]    According to another example embodiment, an imprint method includes injecting the fluid into the inner chamber of the stamp to increase an internal pressure of the inner chamber and thus to inflate the transparent body of the stamp; coating a resin on a substrate; and contacting the stamp, in which the transparent body is inflated, with the substrate coated with the resin. 
         [0018]    The imprint method may further include reducing the pressure of the inner chamber of the transparent body after the stamp contacts the substrate coated with the resin. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0019]    These and/or other aspects will become apparent and more readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings of which: 
           [0020]      FIG. 1  is a cross-sectional view of a stamp according to an example embodiment; 
           [0021]      FIG. 2  is a plan view of the stamp illustrated in  FIG. 1 ; 
           [0022]      FIGS. 3 and 4  are cross-sectional views of stamps according to other example embodiments; 
           [0023]      FIG. 5  is a plan view of a stamp according to another example embodiment; 
           [0024]      FIGS. 6A through 6E  are cross-sectional views for describing an imprint process using the stamp according to an example embodiment; 
           [0025]      FIG. 7  is a cross-sectional view of a stamp according to another example embodiment; and 
           [0026]      FIG. 8  is a cross-sectional view showing an example in which the stamp illustrated in  FIG. 7  is inflated. 
       
    
    
     DETAILED DESCRIPTION 
       [0027]    Reference will now be made in detail to embodiments, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to the like elements throughout. In this regard, the present embodiments may have different forms and should not be construed as being limited to the descriptions set forth herein. Accordingly, the embodiments are merely described below, by referring to the figures, to explain aspects of the present description. 
         [0028]      FIG. 1  is a cross-sectional view of a stamp  10  according to an example embodiment.  FIG. 2  is a plan view of the stamp  10  illustrated in  FIG. 1 . 
         [0029]    Referring to  FIGS. 1 and 2 , the stamp  10  includes an inner chamber  30  and a transparent body  20  having an inlet/outlet tube  35  through which a fluid flows into or out of the inner chamber  30 . An uneven part  50  may be formed on a lower surface  21  of the transparent body  20 . 
         [0030]    The transparent body  20  may have a seamless single body structure. The transparent body  20  may be formed of a material capable of being internally processed by using a laser to form the inner chamber  30  and the inlet/outlet tube  35 . For example, the transparent body  20  may be formed of quartz. 
         [0031]    The stamp  10  may have an inner pressing system and is formed by internally processing a transparent blank, e.g., a quartz blank, by using a laser, e.g., a femtosecond laser, so as to form the inner chamber  30  and the inlet/outlet tube  35  through which a fluid flows into or out of the inner chamber  30 . By forming the stamp  10  in this manner, the transparent body  20  has a seamless single body structure and the inner chamber  30  and the inlet/outlet tube  35  may be obtained such that when the fluid is injected into the inner chamber  30  an internal pressure of the inner chamber  30  may be rapidly adjusted resulting in conformal contact characteristics with a substrate may be improved. 
         [0032]    When a femtosecond laser is used, since an inner part of a transparent blank may be easily processed to a level of about 1 μm, the inner chamber  30  may be formed relatively closely to the lower surface  21  of the stamp  10  (where the uneven part  50  is formed). Also, due to the laser processing, the inner chamber  30  may have a small size. Further, due to the laser processing, the inner chamber  30  may be formed to have various shapes, e.g., a three-dimensional (3D) shape. 
         [0033]    When the internal pressure of the inner chamber  30  is increased, a thin portion of the transparent body  20  under the inner chamber  30  may be easily inflated and thus conformal contact characteristics with a substrate may be improved. 
         [0034]    Since the inner chamber  30  is formed in the transparent body  20  and thus the stamp  10  may have flat outer surfaces except for the lower surface  21  where the uneven part  50  is formed, the stamp  10  may be easily handled by using a typical handling device and may have a simple structure merely required to externally connect a passage for flowing a fluid such as a gas or a liquid. Also, since the transparent body  20  is formed as a seamless single body, a complicated gas leakage prevention device may not be required. 
         [0035]    The inner chamber  30  may have various shapes. The inner chamber  30  may have a shape in which at least a portion of a surface of the inner chamber  30  relatively close to the uneven part  50 , i.e., a bottom surface of the inner chamber  30 , is flat, convex, or concave as illustrated in  FIG. 1 ,  3 , or  4 , when a fluid is not injected.  FIG. 1  shows an example in which the surface of the inner chamber  30  relatively close to the uneven part  50 , i.e., the bottom surface of the inner chamber  30 , is flat.  FIGS. 3 and 4  respectively show examples in which the surface of the inner chamber  30  relatively close to the uneven part  50 , i.e., the bottom surface of the inner chamber  30 , is respectively convex and concave. 
         [0036]    Also, the inner chamber  30  may have overly a circular shape as illustrated in  FIG. 2 . Alternatively, the inner chamber  30  may have overly a rectangular shape as illustrated in  FIG. 5  or may have various polygonal shapes. 
         [0037]    The uneven part  50  may be formed on the lower surface  21  of the transparent body  20 . For example, a pedestal  25  may protrude on the lower surface  21  of the transparent body  20  and the uneven part  50  may be formed on the pedestal  25 . The pedestal  25  may be single body with the transparent body  20 . That is, when the transparent blank is formed, the transparent blank may be processed to have the pedestal  25 . Alternatively, the pedestal  25  may be additionally formed as a transparent layer on the transparent blank before the laser processing is performed, or on the transparent body  20  including the inner chamber  30  and the inlet/outlet tube  35  after the laser processing is performed. In this case, the pedestal  25  may be formed of a transparent material the same as or different from the material of the transparent body  20 . 
         [0038]    The uneven part  50  may be formed of a material the same as or different from the material of the transparent body  20 . The uneven part  50  may include one or more protrusions P 1 . A plurality of protrusions P 1  may be spaced apart from each other. An empty space between two neighboring protrusions P 1  forms a “recess”. The uneven part  50  may have a structure in which the protrusions P 1  and the recesses are alternately disposed. The protrusions P 1  may have a nano-size width. That is, the width of the protrusions P 1  may be about several to several hundred nm, e.g., about several to several ten nm. The distance between the protrusions P 1  may also be about several to several hundred nm, e.g., about several to several ten nm. 
         [0039]    When the uneven part  50  has an uneven pattern including protrusions P 1  that are spaced apart from one another by a nanoscale distance then the stamp  10  may be used in a nanoimprint process. That is, when the stamp  10  in which an uneven pattern having the nanoscale protrusions P 1  is formed on the uneven part  50  is used, a nanoimprint pattern may be formed. 
         [0040]    The above-described stamp  10  may be obtained by laser processing a seamless transparent blank to form the inner chamber  30  and the inlet/outlet tube  35  through which a fluid flows into or out of the inner chamber  30 , and forming the uneven part  50  on the lower surface  21  of the transparent body  20 . 
         [0041]    According to the above-described stamp  10 , in a step and flash imprint lithography (S-FIL) process, when the fluid such as a gas or a liquid is injected into the inner chamber  30  to increase the internal pressure of the inner chamber  30  and thus to inflate a thin portion of the transparent body  20  under the inner chamber  30 , conformal contact characteristics with a substrate may be improved such that a resin may be rapidly coated. 
         [0042]    According to the above-described stamp  10 , the internal pressure of the inner chamber  30  may be rapidly adjusted because the inner chamber  30  has a relatively small size and the stamp  10  may be easily handled by using a typical blank handling device because a central portion of the stamp  10  is not recessed. Also, since a femtosecond laser allows processing to a level of about 1 μm, the inner chamber  30  may be formed relatively closely to the lower surface  21  of the stamp  10 , that is, where an imprint pattern is formed, and may be formed to have a 3D shape. 
         [0043]      FIGS. 6A through 6E  are cross-sectional views for describing an imprint process using the stamp  10 , according to an example embodiment. When the uneven part  50  of the stamp  10  has a nanoscale uneven pattern, a nanoimprint pattern may be formed. 
         [0044]    Initially, as illustrated in  FIG. 6A , the stamp  10  is prepared. 
         [0045]    Then, when a fluid such as a gas or a liquid is injected into the inner chamber  30  of the stamp  10  through the inlet/outlet tube  35 , as illustrated in  FIG. 6B , the internal pressure of the inner chamber  30  is increased and a thin portion of the transparent body  20  relatively close to where the uneven part  50  is formed is inflated, as illustrated in  FIG. 6C . 
         [0046]    When a resin  80  is coated on a substrate  70 , as illustrated in  FIG. 6D , and when the stamp  10  in which the portion of the transparent body  20  relatively close to where the uneven part  50  is formed is inflated contacts the substrate  70  coated with the resin  80 , so as to form a resin layer  90 , as illustrated in  FIG. 6   e , the pattern of the uneven part  50  of the stamp  10  may be transferred to the resin layer  90 . In this case, the pressure of the inner chamber  30  may be reduced while the stamp  10  contacts the substrate  70  coated with the resin layer  90 . In this case, conformal contact may be achieved and the resin  80  may be coated more rapidly. The resin  80  may be an ultraviolet (UV)-curable liquid imprint resin. Here, the resin layer  90  may refer to a layer of the resin  80  that is pressed and spread by the stamp  10 . 
         [0047]    When the stamp  10  is separated form the resin layer  90  after the resin layer  90  is pressed by the stamp  10 , an inverse imprint pattern of the pattern of the uneven part  50  of the stamp  10  may be formed. Before the stamp  10  is separated, a desired (or, alternatively predetermined) curing process may be performed on the resin layer  90 . That is, the stamp  10  may be separated after the resin layer  90  is cured. In this case, since the stamp  10  is overall transparent, the resin layer  90  may be cured, for example, by irradiating UV rays. 
         [0048]    When the nanoscale protrusions P 1  are formed on the uneven part  50 , the imprint process may be a nanoimprint process and thus a nanoimprint pattern may be formed. 
         [0049]    As described above, an imprint pattern, e.g., a nanoimprint pattern, may be formed by coating the resin  80  on the substrate  70 , pressing the transparent stamp  10  onto the resin  80 , and then curing the resin  80 . Here, the stamp  10  may also be used in, for example, a thermal imprint method using heat to cure the resin layer  90 . In this case, the stamp  10  may not be limited to a transparent material. 
         [0050]    According to the above-described imprint method using the stamp  10 , conformal contact between the substrate  70  and the stamp  10  may be achieved, a time taken to coat the resin  80  may be reduced, and thus productivity of an S-FIL process may be improved when compared to imprint methods using a conventional stamp. 
         [0051]    Also, since the inner chamber  30  is formed in the stamp  10 , the stamp  10  may be easily handled by using an existing transparent blank handling device. 
         [0052]    Furthermore, since a femtosecond laser allows processing of quartz to a level of about 1 μm, the inner chamber  30  may be formed relatively closely to the uneven part  50  and may have a relatively small size, and thus a portion of the transparent body  20  under the inner chamber  30  may be easily deformed, and thus an internal pressure of the inner chamber  30  may be rapidly adjusted. 
         [0053]    Although the inner chamber  30  is formed relatively closely to the lower surface  21  of the stamp  10  in the above descriptions, the inner chamber  30  of the stamp  10  may be formed in an upper portion of the stamp  10  or may be formed in a vertical direction. 
         [0054]    For example, as illustrated in  FIG. 7 , the inner chamber  30  may be formed in an upper portion of the stamp  10 . In this case, when a fluid such as a gas or a liquid is injected into the inner chamber  30  of the stamp  10  through the inlet/outlet tube  35 , as illustrated in  FIG. 8 , the internal pressure of the inner chamber  30  is increased and a thin upper portion of the transparent body  20  relatively far from where the uneven part  50  is formed is inflated. In this case, when the stamp  10  is pressed from an upper part, the upward inflated portion uniformly disperses a force of pressing the stamp  10 . Accordingly, when the inner chamber  30  is formed in the upper portion of the stamp  10 , it is possible to press further uniformly. 
         [0055]    Here, even when the inner chamber  30  is formed in the upper portion of the stamp  10 , as illustrated in  FIGS. 7 and 8 , the inner chamber  30  may have various shapes as described above with reference to  FIGS. 3 and 4 . 
         [0056]    As described above, according to one or more of the above example embodiments, when an inner chamber is formed in a lower portion of a stamp, in an S-FIL process, since a fluid such as a gas or a liquid is injected into the inner chamber of the stamp to increase an internal pressure of the inner chamber and thus to inflate a thin portion of a transparent body under the inner chamber, conformal contact characteristics with a substrate may be improved such that a resin may be rapidly coated. Also, when the inner chamber is formed in an upper portion of the stamp, it is possible to press further uniformly. Furthermore, when the inner chamber is formed in a vertical direction, accurate alignment may be achieved. 
         [0057]    It should be understood that the example embodiments described therein should be considered in a descriptive sense only and not for purposes of limitation. Descriptions of features or aspects within each embodiment should typically be considered as available for other similar features or aspects in other embodiments.