Patent Publication Number: US-2010112310-A1

Title: Substrate Patterning

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application claims the priority to, and the benefit of, U.S. Provisional Application No. 61/109,519 filed Oct. 30, 2008, titled “Substrate Patterning,” the entire contents of which are incorporated herein by reference. 
    
    
     BACKGROUND INFORMATION 
     Nano-fabrication includes the fabrication of very small structures that have features on the order of 100 nanometers or smaller. One application in which nano-fabrication has had a sizeable impact is in the processing of integrated circuits. The semiconductor processing industry continues to strive for larger production yields while increasing the circuits per unit area formed on a substrate, therefore nano-fabrication becomes increasingly important. Nano-fabrication provides greater process control while allowing continued reduction of the minimum feature dimensions of the structures formed. Other areas of development in which nano-fabrication has been employed include biotechnology, optical technology, mechanical systems, and the like. 
     An exemplary nano-fabrication technique in use today is commonly referred to as imprint lithography. Exemplary imprint lithography processes are described in detail in numerous publications, such as U.S. Patent Publication No. 2004/0065976, U.S. Patent Publication No. 2004/0065252, and U.S. Pat. No. 6,936,194, all of which are hereby incorporated by reference. 
     An imprint lithography technique disclosed in each of the aforementioned U.S. patent publications and 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 coupled to a motion stage to obtain a desired positioning to facilitate the patterning process. The patterning process uses a template spaced apart from the substrate and a formable liquid applied between the template and the substrate. The formable liquid is solidified to form a rigid layer that has a pattern conforming to a shape of the surface of the template that contacts the formable liquid. After solidification, the template is separated from the rigid layer such that the template and the substrate are spaced apart. The substrate and the solidified layer are then subjected to additional processes to transfer a relief image into the substrate that corresponds to the pattern in the solidified layer. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
       So that the present invention may be understood in more detail, a description of embodiments of the invention is provided with reference to the embodiments illustrated in the appended drawings. It is to be noted, however, that the appended drawings illustrate only typical embodiments of the invention, and are therefore not to be considered limiting of the scope. 
         FIG. 1  illustrates a simplified side view of one embodiment of a lithographic system in accordance with the present invention. 
         FIG. 2  illustrates a simplified side view of the substrate shown in  FIG. 1  having a patterned layer positioned thereon. 
         FIG. 3  illustrates simplified side views of formation of an exemplary patterned layer on substrate having multiple patterns using imprint lithography. 
         FIG. 4  illustrates simplified side views of formation of an exemplary patterned layer on substrate using imprint lithography. 
         FIG. 5  illustrates a simplified side view of the substrate and a fluid dispensing system. 
         FIG. 6  illustrates simplified side views of formation of an exemplary patterned layer on substrate. 
         FIG. 7  illustrates a process flow diagram implementing a method described in the present disclosure. 
         FIG. 8  illustrates a process flow diagram implementing a method described in the present disclosure. 
         FIG. 9  illustrates a process flow diagram implementing a method described in the present disclosure. 
         FIG. 10  illustrates simplified side views of an imprint lithography template that has been altered to provide identifying markings. 
     
    
    
     DETAILED DESCRIPTION 
     Referring to the figures, and particularly to  FIG. 1 , illustrated therein is a lithographic system  10  used to form a relief pattern on substrate  12 . Substrate  12  may be coupled to substrate chuck  14 . As illustrated, substrate chuck  14  is a vacuum chuck. Substrate chuck  14 , however, may be any chuck including, but not limited to, vacuum, pin-type, groove-type, electromagnetic, and/or the like. Exemplary chucks are described in U.S. Pat. No. 6,873,087, which is hereby incorporated by reference. 
     Substrate  12  and substrate chuck  14  may be further supported by stage  16 . Stage  16  may provide motion about the x-, y-, and z-axes. Stage  16 , substrate  12 , and substrate chuck  14  may also be positioned on a base (not shown). 
     Spaced-apart from substrate  12  is a template  18 . Template  18  generally includes a mesa  20  extending therefrom towards substrate  12 , mesa  20  having a patterning surface  22  thereon. Further, mesa  20  may be referred to as mold  20 . Template  18  and/or mold  20  may be formed from such materials including, but not limited to, fused-silica, quartz, silicon, organic polymers, siloxane polymers, borosilicate glass, fluorocarbon polymers, metal, hardened sapphire, and/or the like. As illustrated, patterning surface  22  comprises features defined by a plurality of spaced-apart recesses  24  and/or protrusions  26 , though embodiments of the present invention are not limited to such configurations. Patterning surface  22  may define any original pattern that forms the basis of a pattern to be formed on substrate  12 . 
     Template  18  may be coupled to chuck  28 . Chuck  28  may be configured as, but not limited to, vacuum, pin-type, groove-type, electromagnetic, and/or other similar chuck types. Exemplary chucks are further described in U.S. Pat. No. 6,873,087, which is hereby incorporated by reference. Further, chuck  28  may be coupled to imprint head  30  such that chuck  28  and/or imprint head  30  may be configured to facilitate movement of template  18 . 
     System  10  may further comprise a fluid dispense system  32 . Fluid dispense system  32  may be used to deposit polymerizable material  34  on substrate  12 . Polymerizable material  34  may be positioned upon substrate  12  using techniques such as drop dispense, spin-coating, dip coating, chemical vapor deposition (CVD), physical vapor deposition (PVD), thin film deposition, thick film deposition, and/or the like. Polymerizable material  34  may be disposed upon substrate  12  before and/or after a desired volume is defined between mold  22  and substrate  12  depending on design considerations. Polymerizable material  34  may comprise a monomer as described in U.S. Pat. No. 7,157,036 and U.S. Patent Publication No. 2005/0187339, all of which are hereby incorporated by reference. 
     Referring to  FIGS. 1 and 2 , system  10  may further comprise an energy source  38  coupled to direct energy  40  along path  42 . Imprint head  30  and stage  16  may be configured to position template  18  and substrate  12  in superimposition with path  42 . System  10  may be regulated by a processor  54  in communication with stage  16 , imprint head  30 , fluid dispense system  32 , and/or source  38 , and may operate on a computer readable program stored in memory  56 . 
     Either imprint head  30 , stage  16 , or both vary a distance between mold  20  and substrate  12  to define a desired volume therebetween that is filled by polymerizable material  34 . For example, imprint head  30  may apply a force to template  18  such that mold  20  contacts polymerizable material  34 . After the desired volume is filled with polymerizable material  34 , source  38  produces energy  40 , e.g., broadband ultraviolet radiation, causing polymerizable material  34  to solidify and/or cross-link conforming to shape of a surface  44  of substrate  12  and patterning surface  22 , defining a patterned layer  46  on substrate  12 . Patterned layer  46  may comprise a residual layer  48  and a plurality of features shown as protrusions  50  and recessions  52 , with protrusions  50  having thickness t 1  and residual layer having a thickness t 2 . 
     The above-mentioned system and process may be further employed in imprint lithography processes and systems referred to in U.S. Pat. No. 6,932,934, U.S. Patent Publication No. 2004/0124566, U.S. Patent Publication No. 2004/0188381, and U.S. Patent Publication No. 2004/0211754, each of which is hereby incorporated by reference. 
     Imprint lithography generally provides precision for replication of nanostructures from template  18 ; however, imprint lithography generally may be limited in creation of multiple, different patterns from template  18 . The ability to create multiple, different patterns from template  18  may enable system  10  to provide descriptive marks (e.g., barcodes, numbers, or identification symbols). For example, descriptive marks may uniquely identify each substrate  12 . Such unique identities may be further used to distinguish replicated templates from a single template replication tool. 
     Previous techniques for creating unique patterns on substrate  12  generally require additional hardware to define a pattern. For example, a beam of light or electrons may be used to selectively pattern substrate  12 . These approaches are considered to be serial and/or sequential operations, and generally have limited patterning throughput. 
     Alternatively, a beam of light (e.g. a laser spot) may be used to directly pattern substrate  12  by ablating the surface thereof. This process may be performed at a quick rate; however, it generally requires special tooling and/or additional process steps. Ablation may also create particle debris and contamination of substrate  12 . 
     Referring to  FIG. 3 , illustrated therein are side views of template  18   a  during an imprint lithography process providing different patterns for identification of substrate  12   a . Generally, multiple patterns may be defined on patterning surface  22   a  of template  18   a . For example, patterns P A-D  may be defined on patterning surface  22   a  of template  18   a  as shown in Phase  0 . Patterns P A-D  may correspond to a region R A-D  defined on substrate  12   a . During Phase  0 , polymerizable material  34  may be selectively deposited on substrate  12   a  in regions R A-D . For example, polymerizable material  34  may be deposited on substrate  12   a  on region R A-D  that corresponds to pattern P A-D  on patterning surface  22   a , or there may be no polymerizable material  34  deposited on specific regions on substrate  12 . For example, as illustrated in  FIG. 3 , polymerizable material  34  may be deposited in regions R A , R C , and R D  corresponding to patterns P A , P C , and P D  on patterning surface  22   a ; however, in region R B , no polymerizable material  34  may be deposited on substrate  12 . 
     After the desired regions R A , R C , and R D  are filled with polymerizable material  34 , template  18   a  may be lowered to substrate  12   a  such that template  18   a  is in contact with the polymerizable material  34 , and source  38  produces energy  40  (shown in  FIG. 1 ), e.g., broadband ultraviolet radiation, causing polymerizable material  34  to solidify and/or cross-link conforming to a shape of a surface  44   a  of substrate  12   a  and patterning surface  22   a  of template  18   a , defining patterned layers  46   a ,  46   c , and  46   d  on substrate  12   a  that correspond to patterns P A , P C , and P D , as shown in Phase  1 . The template  18   a  may then be removed (Phase  2 ) and patterned layers  46   a ,  46   c , and  46   d  etched (e.g., descum etch) as shown in Phase  3 . The patterned layers  46   a ,  46   c , and  46   d  may then be further etched into substrate  12   a  (Phase  4 ). 
     Patterned layers  46   a ,  46   c , and  46   d  may have distinct patterns and/or similar patterns. For example, patterned layers  46   a ,  46   c , and  46   d  may have distinct patterns providing for a descriptive mark that uniquely identifies the substrate  12   a . Additionally, the distinct pattern may be provided by the lack of patterned layers  46  on substrate  12   a . For example, a distinct pattern may be formed by the non-use of pattern P B  providing a gap between patterned layer  46   a  and  46   c . For example, a number, a symbol, or a binary number may be derived from the distinct patterns that are formed on the substrate. 
     Referring to  FIG. 4 , template  18   c  may be fabricated with a number of patterns P 1-N  designed with unique diffraction characteristics that may be identified by optical scanners. For example, patterns P 1-N  may be grating or checkerboard patterns. Such patterns P 1-N  may be arranged in an array on template  18   c  to facilitate optical scanning of patterns P 1-N . Each pattern P 1-N  may form a number, symbol, or binary number. For example, each pattern may be assigned a bit value (e.g., 1, 2, 3 . . . N, wherein N equals the number of patterns in the array). During imprinting, each pattern P 1-N  may be associated with region R 1-N  of substrate  12   c . Polymerizable material  34  may be selectively deposited or positioned on substrate  12   c  in regions R 1-N . If polymerizable material  34  is deposited within a region R, the associated pattern P may be designated as “on.” For example, if polymerizable material  34  is deposited in region R 3 , the associated pattern P 3  may be designated as “on.” If polymerizable material  34  is not deposited within a region R, the associated pattern P may be designated as “off.” For example, if polymerizable material  34  is not deposited in region R 2 , the associated pattern P 2  may be designated as “off.” It should be noted the region R 2  is flush with the substrate surface. Using pattern designations of “on” and “off,” patterns P 1-N  may encode any binary number up to 2 N . For example, patterns P 1-30  may provide up to one billion distinct bar codes that may be patterned on substrate  12   c.    
     Referring to  FIGS. 5-6 , a drop deposition apparatus  60  may be used to dispense a resist pattern  61 . Resist pattern  61  may be formed on substrate  12 , a replica template (not shown), or a master template (not shown). For simplicity in description, the following describes formation of the resist pattern  61  on substrate  12 . 
     Generally, the drop deposition device  60  may dispense fluid  62  on a multi-layer substrate  64 . In an embodiment, multi-layer substrate  64  may comprise include chrome or quartz. The fluid  62  remains on multi-layer substrate  64  during an imprint process (as described above) and results in resist pattern  61  that may be readable by a user&#39;s eye and/or machine application. Resist pattern  61  may be any original pattern that may be used for identification of substrate  12 . For example, the original pattern may be a number, symbol, or binary number. 
     Exemplary drop deposition devices  60  may include, but are not limited to, piezo inkjets, MEMs base printheads, and the like. Fluid  62  may be any fluid that provides resist pattern  61  readable by user&#39;s eye and/or machine application. Generally, fluid  62  remains on multi-layer substrate  64  during etching. For example, fluid  62  is generally not removable during chrome and/or quartz etching. One example of fluid  62  may be JetStream ink manufactured by Sunjet a corporation located in Amelia, Ohio, 
       FIG. 6  illustrates simplified side views of an exemplary formation of substrate  12 . Substrate  12  is generally formed from multi-layer substrate  64  (Phase  0 ) having fluid  62  dispensed on thereon. The resulting substrate  12  (see Phase  2 ) comprises resist pattern  61 . 
     Multi-layer substrate  64  may comprise a substrate layer  68  and a hard mask layer  70 . Substrate layer  68  may be formed of materials including, but not limited to, fused-silica, quartz, silicon, organic polymers, siloxane polymers, borosilicate glass, fluorocarbon polymers, metal, hardened sapphire, and/or the like. Hard mask layer  70  may be formed from materials including, but not limited to, tantalum, tantalum nitride, tungsten, silicon carbide, amorphous silicon, chromium, chromium nitride, molybdenum, molybdenum silicide, titanium, titanium nitride, and/or the like. For example, hard mask layer  70  may be a chrome film of approximately 160 angstroms. 
     Generally, fluid  62  remains on multi-layer substrate  64  during the imprint process. In lithography Phase  1 , fluid  62  may substantially shield a portion P of hard mask layer  70  during hard mask layer etching (e.g. chrome etching). For example, as illustrated in  FIG. 6 , portions P 1  and P 2  of hard mask layer  70  may be substantially shielded by fluid drops  62   a  and  62   b  during substrate etching (e.g. quartz etching). In lithography Phase  2 , fluid  62  may substantially shield a portion P s  of substrate layer  68  as well as portion P of hard mark layer  70 . For example, as illustrated in Phase  2 , portions P 1  and Ps 1  may be substantially shielded by fluid drop  62   a  and portions P 2  and Ps 2  may be substantially shielded by fluid drop  62   b . The resulting substrate  12  comprises resist pattern  61 . 
       FIG. 7  illustrates examples of regions  700  within a substrate that have localized portions that have a different index of refraction than other regions in the substrate. The regions that have altered index of refractions may be used to identify the substrate in which they reside. For example, a number, a symbol, or a binary number may be derived from the relative positions of the altered and unaltered regions. 
     Region  702  is a region within a substrate, such as an imprint lithography template, that includes protruding portions  706  and the region is comprised of a first index of refraction  704 . Region  702  may be considered an unaltered region. In one embodiment, region  708  includes a localized portion  710  that has been altered to be comprised of a second index of refraction. The second index of refraction may be lower or higher than the first index of refraction. The altered portion  710  may be created by focused laser beams that locally alter the index of refraction within a substrate by changing the density of the material at the intersection of the focused laser beams. Region  712  is another embodiment of a region that contains different indexes of refraction. For example, portions  714  have a different index of refraction than portions  716 . As shown in  FIG. 7 , the altered portions  714  are confined to a plurality of localized portions beneath the non-protruding portions of region  712 . In yet another embodiment, region  718  includes two portions with different indexes of refraction,  720  and  722 . As shown in  FIG. 7 , the altered portions  720  are included in a localized region that includes the protruding portions of region  718  and the altered portion  720  may extend into the substrate in the area directly below the protruding portion. Portion  722  is the unaltered portion for region  718 . 
     Exemplary Methods 
     Specifics of exemplary methods are described below. However, it should be understood that certain acts need not be performed in the order described, and may be modified, and/or may be omitted entirely, depending on the circumstances. 
       FIG. 8  illustrates an exemplary method  800  for creating descriptive marks on a substrate that are used to identify the individual substrate. The embodiment described in  FIG. 4  will be used to explain the exemplary method described in  FIG. 8 . 
     At  802 , a plurality of drops of a polymerizable fluid  34  is selectively deposited onto selected regions R 1 , R 2 , R N  of the substrate  12   c . The arrangement of the drops will set the location of the protruding portions of a descriptive mark that will be used to identify the substrate. The drops will be selectively deposited in various orientations where each orientation may be considered a distinct descriptive mark for identification purposes. For example, each orientation or position of the protruding portions on the substrate may represent a different number, symbol, or binary number as described above in regards to  FIG. 4 . 
     At  804 , the plurality of drops of a polymerizable fluid  34  are compressed against the substrate  12   c  using an imprint lithography template  18   c  such that a pattern P 1  is formed on drop R 1  as shown in  FIG. 4 . The pattern may be a checkerboard pattern, a grating pattern, or any other pattern that results in a protruding surface from the drop R 1 . The plurality of drops R 1 , R 3 , R N , will together form a descriptive mark. 
     At  806 , the substrate is etched such that the descriptive mark is incorporated into the substrate and the descriptive mark may be used to identify the substrate. The descriptive mark may include portions which protrude from the substrate. The portions that protrude, such as R N  in phase  4  in  FIG. 4 , are assigned a first value, the portions that are flush with the substrate surface, such as R 2  in phase  0  of  FIG. 4 , are given a second value. The relative positions of the protruding portions and the non-protruding portions within the descriptive mark (R 1 , R 2 , R 3 , and R N ) may be used to form a number, a symbol, or to encode a binary number. For the binary number embodiment, the protruding portions are assigned a first value, either “ON” or “1”, and the non-protruding portions are assigned a second value, either “OFF” or “0.” Alternatively, the protruding portions may be assigned a value of “OFF” or “0” and the non-protruding portions may be assigned a value of “ON” or “1.” Varying the positions of the protruding and non-protruding portions within the descriptive mark will allow the descriptive mark to represent a variety of binary numbers. 
       FIG. 9  illustrates an exemplary method  900  for creating descriptive marks on a substrate that are used to identify the individual substrate. The embodiment described in  FIGS. 5 and 6  will be used to explain the exemplary method described in  FIG. 9 . 
     At  902 , a plurality of drops of polymerizable fluid  62  is selectively deposited onto a multi-layer substrate  64  to form a patterned array  61 . In one embodiment, the multi-layer substrate will include a hard mask layer  70  and a substrate layer  68 . The selective deposition of the drops  62  will form a patterned array  61 . The selective deposition of the drops  62  may vary the number of the drops deposited. 
     At  904 , the multi-layer substrate  64  is etched such that the plurality of drops of polymerizable fluid  62  are used as a mask in the etch process, such that the portion of the substrate underneath a drop is not etched away. For example, the portions of the substrate under each drop will protrude from the surface of the substrate, see phase  2   FIG. 6 . The pattern of protruding portions  61 , or the patterned array, may be used to identify the multi-layer substrate. For example, the patterned array  61  may form a recognizable number or mark that is readable by a human eye or by an optical scanner. Additionally, in another embodiment, the patterned array may form a series of protruding portions that may be used to form a descriptive mark, a symbol, or encode binary numbers based on the relative positions of the protruding portions to each other. 
       FIG. 10  illustrates an exemplary method  1000  for creating descriptive marks on a substrate that are used to identify the individual substrate. The embodiment described in  FIG. 7  will be used to explain the exemplary method described in  FIG. 10 . 
     At  1002 , a substrate with a plurality of regions, similar to region  702 , is provided. In one embodiment, the first index of refraction  704  of the substrate is uniform within and around the protruding portions  706 . In one embodiment, the substrate may be an imprint lithography template. 
     At  1004 , a plurality of localized portions within the region  708  is altered to include a second index of refraction. In one embodiment, a region  708  includes altered localized portions  710  which may include several protruding and non-protruding portions of the substrate. In another embodiment, the region  712  includes altered localized portions  714  which may only include non-protruding portions of the region  712  and portions  716  that are still unaltered, such that they are comprised of the first index of refraction  704 . In yet another embodiment, the region  718  includes altered portions  720 , which may include portions of the protruding portions and non-protruding portions, and other portions  722  which may still be comprised of the first index of refraction. 
     At  1006 , the substrate comprised of altered and non-altered regions may be identified based on the orientation of the altered regions, such as region  708 , to each other or with respect to the other regions within the substrate that were not altered, like region  702 . For example a number, a human readable character, a reference mark, an alignment target, a bar code, a binary number and the like may be derived from the relative positions of the altered and unaltered regions within the substrate. In one embodiment, identification of the substrate may occur by comparing the relative position of an altered region  708  to other altered and unaltered regions (not shown) on the substrate to form a number, a symbol, or a binary number that is used to identify the substrate. For example, the altered regions are assigned a value of “1” or “ON” and the unaltered regions are assigned a value of “0” or “OFF” to be used to determine a binary number that identifies the substrate. In an alternative embodiment, the altered regions may be assigned a value of “0” or “ON” and the unaltered regions may be assigned a value of “1” or “ON.” As described above for  FIG. 4 , the different index of refraction regions or different values may be used to form a descriptive mark, symbol, or encode binary number based on the relative positions of the altered and non-altered regions within the substrate. In another embodiment, identification of the substrate may occur by comparing the relative positions of altered regions, similar to regions  708  or  712 , to other altered and unaltered regions (not shown) on the substrate to determine a descriptive mark, symbol, or encode a binary number that identifies the substrate. 
     Although the subject matter has been described in language specific to structural features and/or methodological acts, it is to be understood that the subject matter defined in the appended claims is not necessarily limited to the specific features or acts described. Rather, the specific features and acts are disclosed as preferred forms of implementing the claims.