Abstract:
An imprint lithography template including, inter alia, a body having a first thickness associated therewith; a patterning layer, having a second thickness associated therewith, comprising a plurality of features, having a third thickness associated therewith.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a Continuation of U.S. patent application Ser. No. 12/130,259 filed on May 30, 2008, which claims priority to U.S. Patent Provisional Application No. 60,940,737; both of which are hereby incorporated by reference. 
     
    
     BACKGROUND INFORMATION 
       [0002]    Nano-fabrication involves the fabrication of very small structures, e.g., having features on the order of nanometers or smaller. One area in which nano-fabrication has had a sizeable impact is in the processing of integrated circuits. As the semiconductor processing industry continues to strive for larger production yields while increasing the circuits per unit area formed on a substrate, nano-fabrication becomes increasingly important. Nano-fabrication provides greater process control while allowing increased reduction of the minimum feature dimension of the structures formed. Other areas of development in which nano-fabrication has been employed include biotechnology, optical technology, mechanical systems and the like. 
         [0003]    An exemplary nano-fabrication technique is commonly referred to as imprint lithography. Exemplary imprint lithography processes are described in detail in numerous publications, such as United States patent application publication 2004/0065976 filed as U.S. patent application Ser. No. 10/264,960, entitled “Method and a Mold to Arrange Features on a Substrate to Replicate Features having Minimal Dimensional Variability”; United States patent application publication 2004/0065252 filed as U.S. patent application Ser. No. 10/264,926, entitled “Method of Forming a Layer on a Substrate to Facilitate Fabrication of Metrology Standards”; and U.S. Pat. No. 6,936,194, entitled “Functional Patterning Material for Imprint Lithography Processes,” all of which are assigned to the assignee of the present invention. 
         [0004]    The imprint lithography technique disclosed in each of the aforementioned United States patent application publications and United States patent includes formation of a relief pattern in a polymerizable layer and transferring a pattern corresponding to the relief pattern into an underlying substrate. The substrate may be positioned upon a stage to obtain a desired position to facilitate patterning thereof. To that end, a patterning device is employed spaced-apart from the substrate with a formable liquid present between the patterning device and the substrate. The liquid is solidified to form a patterned layer that has a pattern recorded therein that is conforming to a shape of the surface of the patterning device in contact with the liquid. The patterning device is then separated from the patterned layer such that the patterning device and the substrate are spaced-apart. The substrate and the patterned layer are then subjected to processes to transfer, into the substrate, a relief image that corresponds to the pattern in the patterned layer. 
         [0005]    It may be desirable to properly align the patterning device with the substrate so that a proper orientation between the substrate and the patterning device may be obtained. To that end, both the patterning device and the substrate may include alignment marks. Previous methods of facilitating alignment between the patterning device and the substrate including positioning a moat around the alignment marks to create an air (or gas) gap with a different index of refraction than the patterning device which causes an interface that can be sensed with optical techniques. However, moats maybe undesirable. More specifically, moated alignment marks are not transferred into the pattern on the substrate; moats may consume a large area; moats affect fluid flow and thus cannot be arbitrarily placed within a patterned area; and for flexible patterning devices, moats do not effectively hold the alignment mark region of the patterning device in superimposition with the formable liquid, causing pattern distortions. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS  
         [0006]      FIG. 1  is a simplified side view of a lithographic system having a patterning device spaced-apart from a substrate; 
           [0007]      FIG. 2  is a side view of the patterning device shown in  FIG. 1 ; 
           [0008]      FIG. 3  is a side view of the patterning device contacting a polymeric material positioned on the substrate, all shown in  FIG. 1 . 
           [0009]      FIG. 4  is a simplified elevation view of the patterning device in superimposition with the substrate, both shown in  FIG. 1 , showing misalignment along one direction; 
           [0010]      FIG. 5  is a top clown view of the patterning device in superimposition with the substrate, both shown in  FIG. 1 , showing misalignment along two transverse directions; 
           [0011]      FIG. 6  is a top down view of the patterning device in superimposition with the substrate, both shown in  FIG. 1 , showing angular misalignment; 
           [0012]      FIG. 7  is a simplified side view of the substrate shown in  FIG. 1 , having a patterned layer thereon; 
           [0013]      FIG. 8  is a side view of the patterning device shown in  FIG. 1 , having a thin film; 
           [0014]      FIG. 9  is a side view of the patterning device shown in  FIG. 1 , having a thick film; 
           [0015]      FIGS. 10   a  and  10   b  are a first example of a distortion plot; 
           [0016]      FIGS. 11   a  and  11   b  are a second example of a distortion plot; and 
           [0017]      FIG. 12  is a side view of the patterning device shown in  FIG. 1 , having a layer positioned thereon. 
       
    
    
     DETAILED DESCRIPTION  
       [0018]    Referring to  FIG. 1 , a system  10  to form a relief pattern on a substrate  12  is shown. Substrate  12  may be coupled to a substrate chuck  14 . Substrate chuck  14  may be any chuck including, but not limited to, vacuum, pin-type, groove-type, or electromagnetic, as described in U.S. Pat. No. 6,873,087 entitled “High-Precision Orientation Alignment and Gap Control Stages for Imprint Lithography Processes,” which is incorporated herein by reference. Substrate  12  and substrate chuck  14  may be supported upon a stage  16 . Further, stage  16 , substrate  12 , and substrate chuck  14  may be positioned on a base (not shown). Stage  16  may provide motion along the x and y axes. 
         [0019]    Referring to  FIGS. 1 and 2 , spaced-apart from substrate  12  is a patterning device  18 . Patterning device  18  may comprise a body  20  and a patterning layer  22 . Patterning layer  22  maybe have a plurality of features  24  defined therein, with features  24  including protrusions  26  and recessions  28 . In a further embodiment, patterning layer  22  may be substantially smooth, and/or planar. Patterning layer  22  may define an original pattern that forms the basis of a pattern to be formed on substrate  12 , described further below. Body  20  may comprise fused-silica, however, in a further embodiment, body  20  may be formed from such materials including, but not limited to, quartz, silicon, organic polymers, siloxane polymers, borosilicate glass, fluorocarbon polymers, metal, and hardened sapphire. Patterning layer  22  may be formed from such materials including, but not limited to, silicon nitride, silicon oxynitride, and silicon carbide. Body  20  may have a thickness t 1 , patterning layer  22  may have a thickness t 2 , and features  24  may have a thickness t 3 . 
         [0020]    Referring to  FIG. 1 , patterning device  18  may be coupled to a chuck  30 , chuck  30  being any chuck including, but not limited to, vacuum, pin-type, groove-type, or electromagnetic, as described in U.S. Pat. No. 6,873,087 entitled “High-Precision Orientation Alignment and Gap Control Stages for Imprint Lithography Processes.” Further, chuck  30  may be coupled to an imprint head  32  to facilitate movement of patterning device  18 . 
         [0021]    System  10  further comprises a fluid dispense system  34 . Fluid dispense system  34  may be in fluid communication with substrate  12  so as to deposit polymeric material  36  thereon. System  10  may comprise any number of fluid dispensers, and fluid dispense system  34  may comprise a plurality of dispensing units therein. Polymeric material  36  may be positioned upon substrate  12  using any known technique, e.g., drop dispense, spin-coating, dip coating, chemical vapor deposition (CVD), physical vapor deposition (PVD), thin film deposition, thick film deposition, and the like. Typically, polymeric material  36  is disposed upon substrate  12  before the desired volume is defined between patterning device  18  and substrate  12 . However, polymeric material  36  may fill the volume after the desired volume has been obtained. 
         [0022]    System  10  further comprises a source  38  of energy  40  coupled to direct energy  40  along a path  42 . Source  38  may produce ultraviolet energy. However, other energy sources may be employed, such as thermal, electromagnetic, visible light and the like. The selection of energy employed to initiate polymerization of polymeric material  36  is known to one skilled in the art and typically depends on the specific application which is desired. Imprint head  30  and stage  16  are configured to arrange patterning device  18  and substrate  12 , respectively, to be in superimposition and disposed in path  42 . Either imprint head  30 , stage  16 , or both vary a distance between patterning device  18  and substrate  12  to define a desired volume therebetween that is filled by polymeric material  36 , as shown in  FIG. 3 . Furthermore, an alignment between patterning device  18  and substrate  12  may be desired. Ascertaining a desired alignment between patterning device  18  and substrate  12  facilitates pattern transfer between patterning device  18  and substrate  12 . 
         [0023]    Referring to  FIG. 4 , to facilitate the above-mentioned alignment of patterning device  18  and substrate  12 , patterning device  18  may include alignment marks  44 , and substrate  12  may include alignment marks  46 . In the present example, it is assumed that desired alignment between patterning device  18  and substrate  12  occurs upon alignment mark  44  being in superimposition with alignment mark  46 . As shown in  FIG. 4 , desired alignment between pattering device  18  and substrate  12  has not occurred, shown by the two marks being offset a distance O. Further, although offset O is shown as being a linear offset in one direction, it should be understood that the offset may be linear along two directions shown as O 1  and O 2 , as shown in  FIG. 5 . In addition to, or instead of, the aforementioned linear offset in one or two directions, the offset between patterning device  18  and substrate  12  may also consist of an angular offset, shown in  FIG. 6  as angle Θ. Multiple alignment masks may also have other offsets in combination (e.g., magnification, skew, and trapezoidal distortions). 
         [0024]    Referring to  FIGS. 1 and 7 , after the desired volume is filled with polymeric material  36  and a desired alignment between patterning device  18  and substrate  12  is obtained, source  38  produces energy  40 , e.g., broadband ultraviolet radiation that causes polymeric material  36  to solidify and/or cross-link conforming to the shape of a surface  48  of substrate  12  and patterning device  18 , defining a patterned layer  50  on substrate  12 . Patterned layer  50  may comprise a residual layer  52  and protrusions  54  and recessions  56 . In a further embodiment, after forming patterned layer  50 , the pattern of patterned layer  50  may be transferred into substrate  12  or an underlying layer (not shown) or used as a functional material. 
         [0025]    System  10  may be regulated by a processor  58  that is in data communication with stage  16 , imprint head  30 , fluid dispense system  34 , and source  38 , operating on a computer readable program stored in memory  60 . 
         [0026]    Referring to  FIGS. 1 and 2 , to that end, as mentioned above, an alignment between substrate  12  and patterning device  18  may be desired. To facilitate the alignment, it may be desired to increase a contrast between patterning device  18  and polymeric material  36  positioned on substrate  12  and, as a result, in-liquid alignment between substrate  12  and patterning device  18  may be achieved. To increase the contrast between patterning device  18  and polymeric material  36 , patterning layer  22  of patterning device  18  may be formed from such materials including, but not limited to, silicon nitride, silicon oxynitride, and silicon carbide, as mentioned above. However, thickness t 2  of patterning layer  22  may be selected to minimize, if not prevent, distortions within patterning layer  22 , described further below. 
         [0027]    Referring to  FIG. 8 , a magnitude of thickness t 2  of patterning layer  22  may result in thin film distortions of patterning layer  22 . More specifically, during formation of patterning layer  22 , patterning layer  22  maybe subjected to an etching process to remove portions thereof to define features  24  therein. However, when thickness t 2  of patterning layer  22  has a magnitude within a range of &lt;20 of thickness t 3  of features  24 , stress relief may be induced within patterning layer  22  resulting in thin film stress distortion of patterning layer  22 , which is undesirable. This is a result of removing portions of patterning layer  22  during etching to define features  24  having a significant size compared to thickness t 2  of patterning layer  22  (i.e. thickness t 3  of features  24 ). Further, as a result of thickness t 1  of body  20  being substantially greater than thickness t 2  of patterning layer  22 , thermal distortions may be small. 
         [0028]    Referring to  FIG. 9 , furthermore, a magnitude of thickness t 2  of patterning layer  22  may result in thermal distortions of patterning layer  22 . More specifically, when thickness t 2  of patterning layer  22  has a magnitude within a range of &gt; 1/350 of thickness t 1  of body  20 , a far field distortion of patterning device  18  may result as a result of thermal expansion differences of the materials comprising body  20  and patterning layer  22 . The aforementioned thermal distortion may cause a tension or a compression effect at an interface of body  20  and patterning layer  22  with nonlinear distribution over features  24 , with a maximum distortion at a perimeter  61  of patterned layer  22 . Furthermore, the aforementioned thermal distortions may cause an out-of-plane bending effect of patterning device  18  that may further increase an in-plane distortion prior to patterning device  18  is in full contact with polymeric material  36  on substrate  12 , such as during proximity alignment. However, as a result of thickness t 2  of patterning layer  22  being substantially greater than thickness t 3  of features  24 , localized distortions from etching patterns may be small. 
         [0029]    Referring to  FIG. 2 , to that end, it may be desired to have thickness t 2  of patterning layer  22  have a thickness or a range of layer thicknesses to minimize, if not prevent, both thin film distortions and thermal distortions of patterning layer  22 , mentioned above. More specifically, thickness t 2  of patterning layer  22  may be defined as: 
         [0000]        c   1   ×t   3   &lt;t   2   &lt;t   1   /c   2    (1) 
         [0030]    wherein c 1  and c 2  are defined to result in greater stability to etch-based stress relief distortion and thermal distortions of patterning layer  22 , wherein c 1  may be greater than 20 and c 2  may be greater than 350. In an example of pattering device  18 , for body  20  having thickness t 1  of 700 μm and features  24  having thickness t 3  of 100 nm, thickness t 2  of patterning layer  22  may be 2 μm. In a further example of patterning device  18 , for body  20  having thickness t 1  of 0.7 mm to 6.35 mm and features  24  having thickness t 3  of 100 nm, thickness t 2  of pattering layer  102  may have a range of 100 nm-5 μm, depending on thin film stresses during deposition of patterning layer  22  and the relative thermal expansion coefficient of the specific composition of patterning layer  22  compared to the composition of body  20 . 
         [0031]    Exemplary x-direction distortion plots for patterning layer  22  having thickness t 2  of 2 μm and a composition of silicon nitride are shown in  FIGS. 10   a,    10   b,    11   a,  and  11   b.    FIGS. 10   a  and  10   b  are 2 micron film distortion on body  20  where thickness t 1  is 6.35 mm for 1° C., E film =300 GPa, and CTE film =3.5 ppm/° C., with  FIG. 10   a  being free to bend and δx max=0.23 nm and  FIG. 10   b  being held flat and δx max=0.11 nm.  FIGS. 11   a  and  11   b  are 2 micron film distortion on body  20  where thickness t 1  is 0.700 micron for 1° C., E film =300 GPa, and CTE film =3.5 ppm/° C., with  FIG. 6   a  being free to bend and δx max=1.1 nm and  FIG. 6   b  being held flat and δx max=0.39 nm. 
         [0032]    Referring to  FIG. 12 , in a further embodiment, a layer  62  may be positioned upon patterned layer  22 . Layer  62  may facilitate separation from polymeric material  36  and/or wetting of polymeric material  36 . In still a further embodiment, layer  62  may comprise an oxide. 
         [0033]    The embodiments of the present invention described above are exemplary. Many changes and modifications may be made to the disclosure recited above, while remaining within the scope of the invention. Therefore, the scope of the invention should not be limited by the above description, but instead should be determined with reference to the appended claims along with their full scope of equivalents.