Abstract:
Provided herein is a method, including etching a first pattern into a mask, wherein the first pattern includes a first set of features corresponding to features of an imprint template; forming a second set of features over and in-between the first set of features by directed self-assembly of a block copolymer composition, wherein the first and second sets of features combine to form a second pattern; and etching the second pattern into a substrate.

Description:
CROSS REFERENCE 
     This application is a division of U.S. patent application Ser. No. 13/363,039, filed Jan. 31, 2012, which is incorporated herein by reference in its entirety. 
    
    
     BACKGROUND 
     Bit patterned media (BPM) disk manufacturing includes fabricating master-templates. Fabricating master-templates includes nano-imprint lithography processes. Nano-imprint lithography includes self-assembly processes to create high density patterns. Self-assembly processes create regular patterns such as hexagonal close packed or square structures used for creating BPM data-patterns. Two or more pattern overlay processes are added to create BPM of servo-patterns. Overlay misalignments create inaccuracies in the master templates. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  shows a block diagram of an overview of a method of self-aligned fully integrated stack fabrication of one embodiment. 
         FIG. 2A  shows a block diagram of an overview flow chart of a method of self-aligned fully integrated stack fabrication of one embodiment. 
         FIG. 2B  shows a block diagram of a continuation of an overview flow chart of a method of self-aligned fully integrated stack fabrication of one embodiment. 
         FIG. 2C  shows a block diagram of a continuation of an overview flow chart of a method of self-aligned fully integrated stack fabrication of one embodiment. 
         FIG. 3A  shows for illustrative purposes only an example of low frequency large servo and data field guiding patterns of one embodiment. 
         FIG. 3B  shows for illustrative purposes only an example of a low frequency large encoded servo field patterns in a high frequency data field background of one embodiment. 
         FIG. 4  shows for illustrative purposes only an example of low-frequency large servo field guiding patterns transfer process of one embodiment. 
         FIG. 5  shows for illustrative purposes only an example of HSQ large servo etching mask process of one embodiment. 
         FIG. 6  shows for illustrative purposes only an example of a large servo high frequency guided self-assembly process of one embodiment. 
         FIG. 7  shows for illustrative purposes only an example of a large servo stack fabrication master template process of one embodiment. 
         FIG. 8A  shows for illustrative purposes only an example of low frequency small servo and data field guiding patterns of one embodiment. 
         FIG. 8B  shows for illustrative purposes only an example of a low frequency small information servo field patterns encoded in a high frequency data field background of one embodiment. 
         FIG. 9  shows for illustrative purposes only an example of low-frequency small servo field guiding patterns transfer process of one embodiment. 
         FIG. 10  shows for illustrative purposes only an example of HSQ small servo etching mask process of one embodiment. 
         FIG. 11  shows for illustrative purposes only an example of a small servo high frequency guided self-assembly process of one embodiment. 
         FIG. 12  shows for illustrative purposes only an example of a small servo stack fabrication master template process of one embodiment. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     In a following description, reference is made to the accompanying drawings, which form a part hereof, and in which is shown by way of illustration a specific example in which the invention may be practiced. It is to be understood that other embodiments may be utilized and structural changes may be made without departing from the scope of the present invention. 
     General Overview: 
     It should be noted that the descriptions that follow, for example, in terms of a method of self-aligned fully integrated stack fabrication is described for illustrative purposes and the underlying system can apply to any number and multiple types of stacks and servo-information. In one embodiment the method of self-aligned fully integrated stack fabrication can be configured using numerous etching and guided self assembly processes. The method of self-aligned fully integrated stack fabrication can be configured to include large servo-field patterns that include servo information and can be configured to include small servo-field patterns that include servo information using the present invention. 
       FIG. 1  shows a block diagram of an overview of a method of self-aligned fully integrated stack fabrication of one embodiment.  FIG. 1  shows the method of self-aligned fully integrated stack fabrication uses a self-aligned fully integrated lithography scheme that avoids overlay steps to create separate data and servo field guiding patterns. The method of self-aligned fully integrated stack fabrication is used to create fully integrated data and servo two dimensional low-frequency guiding patterns  100 . The two dimensional low-frequency guiding patterns for the data-fields include traditional sparse hexagonal guiding structures. Larger servo-field patterns guiding structures are created to be compatible with the natural patterns of the low-frequency data-field guiding patterns including the sparse hexagonal guiding structures of one embodiment. 
     The low-frequency data-field and larger servo information guiding structures are combined into one integrated set of guiding patterns to avoid using overlays of separate data and servo patterns which may cause inaccuracies during the stack fabrication process. The combined integrated set of guiding patterns enables encoding servo information into the low-frequency servo-field patterns at the same time for transfer into the stack during fabrication of one embodiment. 
     A process is used to etch low-frequency guiding patterns into an imprint substrate to imprint a resist layer deposited on an image layer  110 . The imprinted resist layer is used to transfer the low-frequency guiding patterns into the image layer deposited onto a template substrate  120 . A single or multi-layered image layer is deposited onto the template substrate. A wet reverse-tone process or a dry reverse-tone process is used to transfer the low-frequency guiding patterns into the image layer. The processes continue to use the low-frequency guiding patterns to guide a self-assembly process to create a high-frequency background  130 . The guided self-assembly process creates a high-frequency background in the data-fields and at the same time creates high-frequency background servo-fields that include the low-frequency encoded servo information. The concurrently created fully integrated data and servo fields can be effectively planarized of one embodiment. 
     In another embodiment a direct-etch process is used to transfer the low-frequency guiding patterns directly into the image layer. A subsequent guided self-assembly process is used to create a high-frequency background of the data-fields and at the same time create the low-frequency encoded servo-fields of one embodiment. 
     The method of self-aligned fully integrated stack fabrication continues with a process to etch the high-frequency data and servo fields and low frequency servo information into the template substrate  140 . The etched substrate including the high-frequency data patterns and the low frequency servo patterns forms a fully integrated stack fabrication master template  150  of one embodiment. 
     DETAILED DESCRIPTION 
     Low-Frequency Guiding Patterns 
       FIG. 2A  shows a block diagram of an overview flow chart of a method of self-aligned fully integrated stack fabrication of one embodiment.  FIG. 2A  shows the method of self-aligned fully integrated stack fabrication begins to create low-frequency guiding patterns  200 . The low-frequency guiding patterns include data-field patterns  202  and larger servo-field patterns  204 . The creation of the larger servo-field patterns  204  may include a process to encode servo-information  206 . The process continues to etch low-frequency guiding patterns into an imprint template  210 . The imprint template is used to transfer the low-frequency guiding patterns into a nano-imprint lithography master-template  212  of one embodiment. 
     The master-template  212  is formed using a substrate  230  using a material such as quartz  232  or silicon  234 . The next step is to deposit an image layer  220  onto the substrate  230 . The image layer may include a single-layer image layer  222  using materials such as chromium (Cr)  224  or amorphous carbon (a-C)  226 . The image layer may include a multi-layer image layer  228 . The next process step is to deposit a resist layer  215  onto the image layer. The description of the processes continues in  FIG. 2B  of one embodiment. 
     Imprinting the Low-Frequency Guiding Patterns: 
       FIG. 2B  shows a block diagram of a continuation of an overview flow chart of a method of self-aligned fully integrated stack fabrication of one embodiment. The process continues from  FIG. 2A  including the low-frequency guiding patterns imprint template and the nano-imprint lithography master-template. In one embodiment the imprint template is used to imprint low-frequency guiding patterns  240  into the resist layer. The imprinted resist layer  242  is cured and may include a descum process. The imprinted resist layer  242  sets on the image layer  244  and substrate  230  of one embodiment. 
     In another embodiment e-beam lithography of low-frequency guiding patterns  236  can be used to transfer the guiding patterns to the resist layer. E-beam lithography by emitting a beam of electrons following the low-frequency guiding patterns exposes the resist layer. An e-beam lithography exposed resist layer  238  can be developed by removing for example the non-exposed areas of the resist layer materials which for example can be removed using a chemical etching process of one embodiment. 
     The transfer of the low-frequency guiding patterns using processes such as the imprint template or e-beam lithography form the topography of the low-frequency guiding patterns in the resist layer on top of the image layer  244  and substrate  230 . In one embodiment a direct-etch process  250  using a process such as ion beam etching  253  is used to etch low-frequency patterns into image layer  254  directly. In another embodiment a reverse-tone process  260  is performed using a wet reverse tone process  262  or dry reverse tone process  264  to transfer the low-frequency guiding patterns into image layer  244 . A continuation of the processing is shown in  FIG. 2C  of one embodiment. 
     Guided Self-Assembly Process: 
       FIG. 2C  shows a block diagram of a continuation of an overview flow chart of a method of self-aligned fully integrated stack fabrication of one embodiment.  FIG. 2C  shows the continuation of the processes from  FIG. 2B . A high frequency guided self-assembly process  270  uses a suitable self-aligning agent  272  to create a high-frequency background. A suitable self-aligning agent  272  such as Poly Styrene-Poly Dimethylsiloxane (PS-PDMS)  274 , Polystyrene Polymethyl Methacrylate (PS-PMMA)  276  or Polystyrene-Polyethylene Oxide (PS-PEO)  278  is used to create high density frequency based on the low-frequency data-field guiding patterns. The structures of the high-frequency data-field patterns  282  may be formed on top of other structures such as etched or imprinted low-frequency patterns. The raised structures produced in the guided self-assembly process are effectively planarized including the low-frequency servo structures. The remaining portions of the high density structures and etched image layer form a mask for an etching process such as e-beam lithography of one embodiment. 
     The process continues with a step to etch patterns into substrate  280 . The etching transfers the high-frequency data-field patterns  282  and the low frequency servo information encoded servo-field patterns in a high frequency background  284  into the substrate material. The remaining portions of the layers deposited on the substrate are removed and the etched substrate cleaned. The remaining etched substrate forms a fully integrated stack fabrication master template  150 . The method of self-aligned fully integrated stack fabrication can be used to produce a bit-patterned stack fabrication master template  290  or any other patterned stack fabrication master template  292  of one embodiment. 
     Low-Frequency Large Servo-Field Guiding Patterns: 
       FIG. 3A  shows for illustrative purposes only an example of low frequency large servo and data field guiding patterns of one embodiment.  FIG. 3A  shows the combined fully integrated low-frequency two dimensional guiding patterns  300 . The two dimensional low-frequency guiding patterns include low-frequency data-field guiding patterns  310 . The low-frequency data-field guiding patterns  310  can be written based on traditional sparse hexagonal guiding structures for the data-fields or other low-frequency guiding structures for example guiding structures which use guided self assembly processes to create a high density of one embodiment. 
     The combined fully integrated low-frequency two dimensional guiding patterns  300  also include low-frequency large servo-field guiding patterns  320 . The low-frequency large servo-field guiding patterns  320  are chosen to be compatible with the natural patterns create by the traditional sparse hexagonal guiding structures for the data-fields. A process to encode servo-information  206  into the low-frequency large servo-field guiding patterns  320  can be used to pattern the servo-information into a stack during the fabrication process. The combined fully integrated low-frequency two dimensional guiding patterns  300  avoids overlaying separate data-field and servo-field patterns which may cause inaccuracies due to miss-positioning of the overlays of one embodiment. 
     High-Frequency Large Servo-Field Master Template: 
       FIG. 3B  shows for illustrative purposes only an example of a low frequency large encoded servo field patterns in a high frequency data field background of one embodiment.  FIG. 3B  shows a large servo-field high-frequency master template  330  into which have been etched the high-frequency data field patterns  282  and low frequency large servo information encoded servo field patterns in a high frequency background  340 . The high-frequency data field patterns  282  are the result of the guided self assembly process. The guided self assembly process is used to create a high density of data-fields structures from the low-frequency data-field guiding patterns  310  of  FIG. 3A  of the combined fully integrated low-frequency two dimensional guiding patterns  300  of  FIG. 3A  of one embodiment. 
     Low-Frequency Large Servo Field Guiding Patterns Transfer Process: 
       FIG. 4 ,  FIG. 5 ,  FIG. 6  and  FIG. 7  show the processes used in one embodiment to transfer the low-frequency guiding patterns to create a high-frequency master template. The low-frequency guiding patterns illustrated in  FIG. 4 ,  FIG. 5 ,  FIG. 6  and  FIG. 7  include for example large servo field guiding patterns. The one embodiment illustrated shows one of various combinations of processes such as e-beam lithography, guided self-assembly processes and direct-etch processes using the two dimensional low-frequency guiding patterns used to create a fully integrated stack fabrication master template of one embodiment. 
       FIG. 4  shows for illustrative purposes only an example of low-frequency large servo field guiding patterns transfer process of one embodiment.  FIG. 4  shows a process to deposit a chromium (Cr) image layer on a quartz substrate  415 . The quartz substrate  400  and chromium (Cr) image layer  410  forms the base of the template used to create the master template of one embodiment. 
     The process proceeds to spin a resist layer onto the image layer  425 . The low-frequency large servo field guiding patterns are etched into a substrate to create a low-frequency large servo field guiding patterns imprint template  430 . The resist layer  420  is used to imprint the low-frequency large servo field guiding patterns. The next step in the imprinting process is to set low-frequency large servo field guiding patterns imprint template into resist layer  435  of one embodiment. 
     An ultraviolet (UV) light source  440  is used to project ultraviolet (UV) light through the low-frequency large servo field guiding patterns imprint template  430  to the resist layer. The resist through capillary action fills the cavities of the low frequency guiding patterns. The process to use ultraviolet (UV) light to cure resist  445  material sets the low-frequency large servo field guiding patterns into the resist to form an imprinted resist layer  460 . A process to lift the low-frequency large servo field guiding patterns imprint template from the imprinted resist layer  450  is completed to reveal the imprinted resist layer  460 . The continuation of the processes is described in  FIG. 5  of one embodiment. 
     HSQ Large Servo Etching Masks Process: 
       FIG. 5  shows for illustrative purposes only an example of HSQ large servo etching mask process of one embodiment.  FIG. 5  shows the continuation processes from  FIG. 4 . The next step may include a process to descum the imprinted resist layer  500 . The next step is to spin hydrogen silsesquioxane (HSQ)  515  on the imprinted resist layer  460  using a HSQ-based wet reverse tone process. The HSQ  510  fills the voids of the imprinted resist layer  460  from the surface of the chromium (Cr) image layer  410  to a level above the imprinted resist layer  460  of one embodiment. 
     The spun HSQ  510  hardens and then is planarized. A HSQ etch-back  525  is used to planarize the HSQ  510 . The planarization of the HSQ is achieved using processes such as chemical etching or mechanical planarization. The planarized HSQ  520  matches the upper surface level of the imprinted resist layer  460 . An etch-back to remove imprinted resist  535  is processed to reveal the reverse tone planarized HSQ  520 . Subsequent processes are described in  FIG. 6  of one embodiment. 
     Large Servo High Frequency Guided Self-Assembly Process: 
       FIG. 6  shows for illustrative purposes only an example of a large servo high frequency guided self-assembly process of one embodiment. A physical or chemical guide-pattern can be used to enforce long-range order during the self assembly process of block-copolymers, or other self-assembling agents such as nano-particles. It has been demonstrated that this approach can result in large arrays of, for example, round dots in a hexagonally close-packed or square arrangement of one embodiment. 
     Continuing from the processes described in  FIG. 5 ,  FIG. 6  shows the next step is to etch into the Cr image layer  620  the low-frequency guiding patterns using a process such as e-beam lithography. An e-beam writer  600  projects e-beams  610  which pass through the areas where the imprinted resist layer  460  of  FIG. 4  have been removed. The e-beams  610  etch the low frequency patterns into the chromium (Cr) image layer  410  to the surface of the quartz substrate  400 . The reverse tone planarized HSQ  520  is resistant to the e-beam etching. A chemical etch back process is used to remove HSQ  630 . The etched chromium (Cr) image layer  640  is revealed and portions of the quartz substrate  400  exposed of one embodiment. 
     A high frequency guided self-assembly process  160  is used to spin poly styrene-poly dimethylsiloxane (PS-PDMS) and anneal  650  the material to harden the high density structures. The highest portions of the high density structures consist of poly styrene (PS)  660 . A chemical process is used to etch-back PS  670 . The etched chromium (Cr) image layer  640  and remaining high frequency PDMS structures form a mask in subsequent etching processes. Processes described in  FIG. 7  show the continuing process of one embodiment. 
     Large Servo Stack Fabrication Master Template Process: 
       FIG. 7  shows for illustrative purposes only an example of a large servo stack fabrication master template process of one embodiment. The etched chromium (Cr) image layer  640  and remaining high frequency PDMS structures masks formed in  FIG. 6  expose portions of the surface of the quartz substrate  400 . A process such as e-beam lithography is used to etch into quartz  700 . The e-beam writer  600  projects e-beams  610  which etch into the exposed surfaces of the quartz substrate  400 . Upon completion of the e-beam etching of the quartz etch back processes are used to remove the PDMS  730  structures and remove Cr  750  in the etched chromium (Cr) image layer  640 . The etched quartz substrate  760  is cleaned of one embodiment. 
     The etched quartz substrate  760  forms the large servo-field high-frequency master template  330 . The low frequency large servo information encoded servo field patterns in a high frequency background  340  and high-frequency data field patterns  282  form the fully integrated stack fabrication master template  150 . The use of the method of self-aligned fully integrated stack fabrication produces a highly accurate fully integrated stack fabrication master template  150  to fabricate bit-patterned stacks and any other patterned stack media of one embodiment. 
     Low-Frequency Small Servo-Field Guiding Patterns: 
       FIG. 8A  shows for illustrative purposes only an example of low frequency small servo and data field guiding patterns of one embodiment.  FIG. 8A  shows one embodiment of the combined fully integrated low-frequency two dimensional guiding patterns  800 . The two dimensional low-frequency guiding patterns include low-frequency data-field guiding patterns  310 . The low-frequency data-field guiding patterns  310  can be written based on hexagonal close packed or square guiding structures for the data-fields or other low-frequency guiding structures for example guiding structures which use guided self assembly processes to create a high density of one embodiment. 
     The combined fully integrated low-frequency two dimensional guiding patterns  800  also include low-frequency small servo-field guiding patterns  810 . The low-frequency small servo-field guiding patterns  810  illustrated are chosen to be compatible with the natural patterns create by the square guiding structures for the data-fields. A process to encode servo-information  206  into the low-frequency small servo-field guiding patterns  810  can be used to pattern the servo-information into a stack during the fabrication process of one embodiment. 
     High-Frequency Small Servo-Field Master Template: 
       FIG. 8B  shows for illustrative purposes only an example of a low frequency small information servo field patterns encoded in a high frequency data field background of one embodiment.  FIG. 8B  shows a small servo-field high-frequency master template  820  into which have been etched the high-frequency data field patterns  282  and low frequency small servo information encoded servo field patterns in a high frequency background  830 . The high-frequency data field patterns  282  are the result of the guided self assembly process using the low-frequency data-field guiding patterns  310  of  FIG. 8A  from the combined fully integrated low-frequency two dimensional guiding patterns  800  of  FIG. 8A  to create a high density of data-fields structures of one embodiment. 
     Low-Frequency Small Servo Field Guiding Patterns Transfer Process: 
       FIG. 9  shows for illustrative purposes only an example of low-frequency small servo field guiding patterns transfer process of one embodiment.  FIG. 9  shows the formation of the base of a master template using a silicon substrate  900 . A process is used to deposit amorphous-carbon (a-C) image layer on stack silicon substrate  910 . An amorphous-carbon (a-C) image layer  920  is used in the transfer of the low-frequency small servo field guiding patterns into the silicon substrate  900  of one embodiment. 
     A low-frequency small servo guiding patterns imprint template  940  is created by etching the low-frequency small servo guiding patterns into a substrate. The transfer process proceeds to spin resist layer onto image layer  425 . The next step is to set low-frequency small servo field guiding patterns imprint template into resist  930 . The resist layer  950  through capillary action fills the cavities of the low frequency guiding patterns of one embodiment. 
     An ultraviolet (UV) light source  440  is used to project ultraviolet (UV) light through the low-frequency small servo guiding patterns imprint template  940  to the resist layer  950 . The process to use ultraviolet (UV) light to cure resist  445  material sets the low-frequency small servo field guiding patterns into the resist to form an imprinted resist layer  970 . A process to lift the low-frequency small servo guiding patterns imprint template  940  from the resist layer  950  is completed to reveal the imprinted resist layer  970  and portions of the surface of the amorphous-carbon (a-C) image layer  920 . The continuation of the processes is described in  FIG. 10  of one embodiment. 
     HSQ Small Servo Etching Masks Process: 
       FIG. 10  shows for illustrative purposes only an example of HSQ small servo etching mask process of one embodiment. Continuing from  FIG. 9 ,  FIG. 10  shows processes which may include a process to descum the imprinted resist layer  500 . The descum process removes possible contaminates from the imprinted resist layer  970  and amorphous-carbon (a-C) image layer  920  on the silicon substrate  900  which may interfere with subsequent processes of one embodiment. 
     A process proceeds to spin hydrogen silsesquioxane (HSQ)  515  over the imprinted resist layer  970  and exposed surfaces of the amorphous-carbon (a-C) image layer  920 . The spun HSQ  510  reaches a level above the imprinted resist layer  970 . A HSQ etch-back  525  lowers the level of the etched HSQ  520  to match the level of the imprinted resist layer  970  of one embodiment. 
     An etch-back to remove imprinted resist  535  exposes HSQ small servo mask  1010  and HSQ low-frequency data mask  1000  structures. The mask structures leave portions of the surface of the amorphous-carbon (a-C) image layer  920  exposed. Processing continues as described in  FIG. 11  of one embodiment. 
     Small Servo High Frequency Guided Self-Assembly Process: 
       FIG. 11  shows for illustrative purposes only an example of a small servo high frequency guided self-assembly process of one embodiment.  FIG. 10  described the formation of the mask structures. The next step is the high frequency guided self-assembly process  160 . The high frequency guided self-assembly process  160  begins with a process to spin polystyrene-polymethylsiloxane (PS-PDMS) and anneal  1100 . The PS-PDMS is spun onto the exposed surfaces of the amorphous-carbon (a-C) image layer  920  of one embodiment. 
     The upper sections of the PS-PDMS structures include polymethylsiloxane (PDMS)  1105  and the lower sections include polystyrene (PS)  1110 . The high density PS-PDMS structures set between the HSQ small servo mask  1010  and HSQ low-frequency data mask  1000  structures. The masks on the amorphous-carbon (a-C) image layer  920  are used in an etching process of the image layer of one embodiment. 
     An ion beam etching process  600  etches into a-C image layer  1140 . The etching is followed by processes to remove PS-PDMS and HSQ  1145 . The removal of the HSQ small servo mask  1120 , HSQ data mask  1125  and PS-PDMS data mask  1130  exposes the etched a-C image layer high frequency data mask  1150  and etched a-C image layer low frequency small servo mask  1160 . Processes continue as described in  FIG. 12  of one embodiment. 
     Small Servo Stacks Fabrication Master Template Process: 
       FIG. 12  shows for illustrative purposes only an example of a small servo stack fabrication master template process of one embodiment.  FIG. 12  shows an e-beam lithography process using an ion beam etching process  1205  that projects an ion beam  610  to etch into silicon substrate  1200 . The etched a-C image layer high frequency data mask  1150  and etched a-C image layer low frequency small servo mask  1160  protect the silicon substrate  900  from undesired etching. A process is used to remove a-C image layer  1210  and expose the etched silicon substrate  1215  of one embodiment. 
     The etched silicon substrate  1215  includes the high frequency data patterns and low frequency small servo patterns  820 . The etched silicon substrate  1215  forms the small servo-field high-frequency master template  1220 . The low frequency small servo information encoded servo field patterns in a high frequency background  830  of  FIG. 8B  and high-frequency data field patterns  282  form the fully integrated stack fabrication master template  150 . Highly accurate fabrication of patterned stacks for example bit-patterned stacks is achievable using the method of self-aligned fully integrated stack fabrication of one embodiment. 
     The foregoing has described the principles, embodiments and modes of operation. However, the invention should not be construed as being limited to the particular embodiments discussed. The above described embodiments should be regarded as illustrative rather than restrictive, and it should be appreciated that variations may be made in those embodiments by workers skilled in the art without departing from the scope as defined by the following claims.