Abstract:
The present invention is directed towards a method of controlling an atmosphere about a substrate, the method including, inter alia, positioning a body a distance from a surface of the substrate, the body having a wall coupled thereto placed in a position to create a flow resistance of a fluid between first and second regions of the substrate; and altering the position of the wall such that when a magnitude of the distance between the body and the surface of the substrate is decreased, a probability of the wall contacting the substrate is minimized.

Description:
CROSS-REFERENCE TO RELATED PATENT APPLICATIONS  
       [0001]     The present application is a divisional patent application of U.S. patent application Ser. No. ______ (Attorney Docket Number P218M1D236), filed herewith and entitled “System to Control an Atmosphere Between a Body and a Substrate,” and listing Yeong-Jun Choi and Byung-Jin Choi as inventors, the entirety of which is incorporated by reference herein. 
     
    
     BACKGROUND OF THE INVENTION  
       [0002]     The field of the invention relates generally to micro-fabrication techniques. More particularly, the present invention is directed to a system of controlling an atmosphere between a mold and a substrate.  
         [0003]     Nano-fabrication involves the fabrication of very small structures, e.g., having features on the order of nano-meters 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.  
         [0004]     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.  
         [0005]     The fundamental 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 motion stage to obtain a desired position to facilitate patterning thereof. To that end, a template is employed spaced-apart from the substrate with a formable liquid present between the template and the substrate. The liquid is solidified to form a solidified layer that has a pattern recorded therein that is conforming to a shape of the surface of the template in contact with the liquid. The template is then separated from the solidified layer such that the template and the substrate are spaced-apart. The substrate and the solidified layer are then subjected to processes to transfer, into the substrate, a relief image that corresponds to the pattern in the solidified layer.  
         [0006]     United States patent application publication 2005/0074512 filed as U.S. patent application Ser. No. 10/898,037 entitled “System for Creating a Turbulent Flow of Fluid between a Mold and a Substrate” describes a system for introducing a flow of a fluid between a mold and a substrate. More specifically, the system includes a baffle coupled to a chuck, the baffle having first and second apertures in communication with a fluid supply to create a turbulent flow of the fluid between the mold and the substrate.  
         [0007]     To that end, it may be desired to provide an improved system of controlling the atmosphere between a mold and a substrate.  
       SUMMARY OF THE INVENTION  
       [0008]     The present invention is directed towards a method of controlling an atmosphere about a substrate, the method including, inter alia, positioning a body a distance from a surface of the substrate, the body having a wall coupled thereto placed in a position to create a flow resistance of a fluid between first and second regions of the substrate; and altering the position of the wall such that when a magnitude of the distance between the body and the surface of the substrate is decreased, a probability of the wall contacting the substrate is minimized. These and other embodiments are described more fully below. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0009]      FIG. 1  is a simplified side view of a lithographic system having walls coupled to an imprint head;  
         [0010]      FIG. 2  is a side view of a portion of the system shown in  FIG. 1 , with the walls placed in a first position;  
         [0011]      FIG. 3  is a side view of a portion of the system shown in  FIG. 1 , with the walls placed in a second position;  
         [0012]      FIG. 4  is a side view of a portion of the lithographic system shown in  FIG. 1 , with a template in contact with a material on a substrate; and  
         [0013]      FIG. 5  is a side view of a portion of the lithographic system shown in  FIG. 1 , with the walls being positioned to expose a portion of an atmosphere between a template and a substrate to an ambient environment. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0014]     A system  10  employed to form a relief pattern in a substrate  12  includes a stage  14  upon which substrate  12  is supported, and a template  16  having a mold  18  with a patterning surface  20  thereon. In a further embodiment, substrate  12  may be coupled to a substrate chuck (not shown), the substrate chuck (not shown) being any chuck including, but not limited to, vacuum and electromagnetic.  
         [0015]     Template  16  and/or mold  18  may be formed from such materials including but not limited to, fused-silica, quartz, silicon, organic polymers, siloxane polymers, borosilicate glass, fluorocarbon polymers, metal, and hardened sapphire. As shown, patterning surface  20  comprises features defined by a plurality of spaced-apart recessions  22  and protrusions  24 . However, in a further embodiment, patterning surface  20  may be substantially smooth and/or planar. The plurality of features of patterning surface  20  defines an original pattern that forms the basis of a pattern to be formed on substrate  12 .  
         [0016]     Template  16  may be coupled to an imprint head  26  to facilitate movement of template  16 , and therefore, mold  18 . In a further embodiment, template  16  may be coupled to a template chuck (not shown), the template chuck (not shown) being any chuck including, but not limited to, vacuum and electromagnetic. A fluid dispense system  27  is coupled to be selectively placed in fluid communication with substrate  12  so as to deposit a polymerizable material  28  thereon. It should be understood that polymerizable material  28  may be deposited using any known technique, e.g., spin-coating, dip coating, chemical vapor deposition (CVD), physical vapor deposition (PVD), and the like. In the present example, however, polymerizable material  28  is deposited as a plurality of spaced-apart discrete droplets  30  on substrate  12 .  
         [0017]     A source  32  of energy  34  is coupled to direct energy  34  along a path  36 . Imprint head  26  and stage  14  are configured to arrange mold  18  and substrate  12 , respectively, to be in superimposition, and disposed in path  36 . Either imprint head  26 , stage  14 , or both vary a distance between mold  18  and substrate  12  to define a desired volume therebetween that is filled by polymerizable material  28 .  
         [0018]     Typically, polymerizable material  28  is disposed upon substrate  12  before the desired volume is defined between mold  18  and substrate  12 . However, polymerizable material  28  may fill the volume after the desired volume has been obtained. After the desired volume is filled with polymerizable material  28 , source  32  produces energy  34 , which causes polymerizable material  28  to solidify and/or cross-link, forming a polymeric material conforming to the shape of a surface  38  of substrate  12  and patterning surface  20  of mold  18 . Control of this process is regulated by processor  40  that is in data communication with stage  14 , imprint head  26 , fluid dispense system  27 , and source  32 , operating on a computer-readable program stored in memory  42 .  
         [0019]     System  10  further comprises a pair of conduits  44   a  and  44   b.  As shown, conduits  44   a  and  44   b  are coupled to imprint head  26 ; however, conduits  44   a  and  44   b  may be coupled to any part of system  10 , i.e., substrate  12 , stage  14 , template  16 , the substrate chuck (not shown), or the template chuck (not shown). Further, system  10  may comprise any number of conduits. Conduits  44   a  and  44   b  may be in fluid communication with a pump system  46  via throughways  48 . As shown, throughways  48  are contained within imprint head  26 . However, in a further embodiment, throughways  48  may be positioned anywhere throughout system  10  and may be coupled to any part of system  10 , i.e., substrate  12 , stage  14 , template  16 , the substrate chuck (not shown), or the template chuck (not shown). Pump system  46  may be in communication with processor  40  operating on memory  42  to control an introduction/evacuation of a fluid  54  in an atmosphere  56  defined between mold  18  and droplets  30 , described further below.  
         [0020]     Further, system  10  comprises walls  50  coupled to imprint head  26 . In a further embodiment, walls  50  may be coupled to any part of system  10 , i.e., substrate  12 , stage  14 , template  16 , the substrate chuck (not shown), or the template chuck (not shown). Walls  50  may be positioned at an interface between first and second regions  58  and  60  of substrate  12 , with first region  58  being in superimposition with mold  18  and droplets  30 . Further, walls  50  may substantially surround imprint head  26 , and therefore, atmosphere  56 . However, for simplicity of illustration, walls  50  are shown surrounding a portion of imprint head  26  and atmosphere  56 .  
         [0021]     Walls  50  may be in communication with a motor  52 , with motor  52  controlling a motion thereof. For simplicity of illustration, motor  52  is shown as two separate bodies. Motor  52  may comprise a solenoid selected from a group of solenoids including but not limited to, electric, pneumatic, and hydraulic. Further, motor  52  may be employed without feedback. Motor  52  may be in communication with processor  40  operating on memory  42 .  
         [0022]     As mentioned above, during imprinting, template  16  and therefore, mold  18 , are brought into proximity with substrate  12  before positioning polymerizable material  28  in droplets  30  upon substrate  12 . Specifically, template  16  is brought within hundreds of microns of substrate  12 , e.g., approximately 200 microns. It has been found desirable to perform localized control of atmosphere  56  that is proximate to both template  16  and substrate  12 . For example, to avoid the deleterious effects of gases and/or gas pockets present in polymerizable material  28  in droplets  30  and/or subsequently trapped in a patterned layer, described further below, formed from droplets  30 , it has been found beneficial to control desired properties of atmosphere  56  and/or the pressure of atmosphere  56 . More specifically, it may be desired to control fluid  54  within atmosphere  56 . To that end, a system and a method to facilitate control of atmosphere  56  is described below.  
         [0023]     Referring to  FIG. 2 , a portion of system  10  is shown. More specifically, mold  18  is shown spaced-apart from surface  38  of substrate  12  a first distance ‘d 1 ’. Distance ‘d 1 ’ may be on the order of hundreds of microns, i.e., approximately 200 to 300 microns. Walls  50  of system  10  are shown placed in a first position spaced-apart a distance ‘d 2 ’ from surface  38  of substrate  12 . Distance ‘d 2 ’ may be on the order of tens of microns, i.e., approximately 50 microns.  
         [0024]     Pump system  46  may introduce fluid  54  into atmosphere  56  through throughways  48  and conduits  44   a  and  44   b.  Fluid  54  may comprise a gas selected from a group of gases including, but not limited to, helium, hydrogen, nitrogen, carbon dioxide, and xenon. Fluid  54  may be introduced into atmosphere  56  through conduits  44   a  and  44   b  employing any desired method. For example, fluid  54  may be introduced through both conduits  44   a  and  44   b  concurrently, or sequentially pulsed through the same, i.e., first fluid is introduced through conduit  44   a  and subsequently through conduit  44   b  and then again through conduit  44   b,  with the process being repeated for a desired time or during the entire imprinting process. Methods for introduction/evacuation of fluid  54  through conduits  44   a  and  44   b  is disclosed in United States patent application publication 2005/0072755 filed as U.S. patent application Ser. No. 10/677,639 entitled “Single Phase Fluid Imprint Lithography Method,” which is incorporated by reference herein in its entirety. In an example, conduits  44   a  and  44   b  may introduce fluid  54  within atmosphere  56  at a flow rate of 9 liters/minute.  
         [0025]     To that end, it may be desired to control atmosphere  56 , and more specifically, it may be desired to maintain fluid  54  within atmosphere  56  preceding to and until contact between mold  18  and polymerizable material  28  in droplets  30 . In a further embodiment, it may be desired to maintain fluid  54  within atmosphere  56  prior to and subsequent to contact between mold  18  and polymerizable material  28  in droplets  30 . In an example, it may be desired to have atmosphere  56  comprise more than a 95% mass fraction of fluid  54  therein. To that end, walls  50  facilitate control of atmosphere  56  by creating a flow resistance between first and second regions  58  and  60  of substrate  12 . More specifically, as mentioned above, walls  50  are spaced-apart a distance ‘d 2 ’ from surface  38  of substrate  12 ; and mold  18 , in superimposition with polymerizable material  28  in droplets  30 , is spaced-apart a distance ‘d 1 ’ from surface  38  of substrate  12 . Further, distance ‘d 1 ’ is substantially greater than distance ‘d 2 ’. As a result, a greater resistance to a flow of fluid  54  is established between walls  50  and surface  38  of substrate  12  than between mold  18  and surface  38  of substrate  12 ; and thus, fluid  54  may tend to be maintained within atmosphere  56 , which may be desired. For a given flow rate of fluid  54  through conduits  44   a  and  44   b  and a given volume of atmosphere  56 , the distance ‘d 2 ’ may be selected to achieve a desired resistance to the flow of fluid  54  between first and second regions  58  and  60  of substrate  12 .  
         [0026]     However, as mentioned above, a desired volume is defined between mold  18  and substrate  12  that is filled by polymerizable material  28  in droplets  30 . More specifically, imprint head  26  may position mold  18  such that polymerizable material  28  in droplets  30  are in contact therewith. As a result, walls  50  may translate to minimize a probability of the same contacting substrate  12  during a decrease in a magnitude of distance ‘d 1 ’, and more specifically, during contact of mold  18  with polymerizable material  28  in droplets  30 . Contact of substrate  12  by walls  50  may result in, inter alia, structural comprise of system  10 , impedance of contact between mold  18  and droplets  30 , misalignment of mold  18  with respect to substrate  12 , and damage to substrate  12  and/or mold  18 , all of which are undesirable.  
         [0027]     Referring to  FIG. 3 , to that end, walls  50  may translate in a first direction away from substrate  12 . More specifically, motor  52  may position walls  50  such that the same are positioned a distance ‘d 3 ’ 0  from surface  38  of substrate  12 , with distance ‘d 3 ’ being greater than distance ‘d 1 ’. Distance ‘d 3 ’ may be on the order of hundreds of microns.  
         [0028]     Referring to  FIG. 4 , mold  18  is shown in mechanical contact with polymerizable material  28 , spreading droplets  30 , shown in  FIG. 1 , so as to generate a contiguous formation  62  of polymerizable material  28  over surface  38  of substrate  12 . Template  16 , and further, mold  18 , may translate in a second direction towards substrate  12 , with the second direction being opposite to the aforementioned first direction. In a further embodiment, stage  14 , and further, substrate  12  may translate in a third direction towards mold  18 , with the third direction being in a direction substantially the same as the first direction. Furthermore, walls  50  may translate in the first direction concurrently or asynchronously with translation of mold  18  and/or substrate  12 .  
         [0029]     Referring to  FIG. 1 , in a preferred embodiment, fluid  54  may be introduced into atmosphere  56  at any time prior to contact between mold  18  and droplets  30 . However, in a further embodiment, introduction of fluid  54  into atmosphere  56  may be ceased at any time.  
         [0030]     Referring to  FIG. 5 , in a preferred embodiment, it may be desired to expose a portion of atmosphere  56 , shown in  FIG. 1 , to an ambient environment to facilitate control of fluid  54  within atmosphere  56 , shown in  FIG. 1 . To that end, walls  50   a  and  50   b  may be positioned distance ‘d 2 ’ from surface  38  of substrate  12 , as mentioned above. However, wall  50   c  may be positioned a distance ‘d 4 ’ from surface  38  of substrate  12 . Distance ‘d 4 ’ may have a magnitude approximately between 200 microns and 1 millimeter. As a result, atmosphere  56  may be exposed to an ambient environment. In a further embodiment, walls  50  may substantially surround imprint head  26 , and thus atmosphere  56 , forming a chamber (not shown). The chamber (not shown) may be completely evacuated or pressurized.  
         [0031]     Referring to  FIG. 2 , in a further embodiment, to increase a quantity of fluid  54  disposed within atmosphere  56 , distance ‘d 1 ’ may be increased prior to contact of mold  18  with droplets  30 . More specifically, distance ‘d 1 ’ may be on the order of millimeters, i.e., approximately 1 millimeter.  
         [0032]     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.