Patent Document

TECHNICAL FIELD 
       [0001]    The present invention relates to fabrication of items, and more particularly, to systems and method of using holography to facilitate optical manufacturing processes. 
       BACKGROUND 
       [0002]    In many manufacturing processes, electromagnetic energy is used to selectively process materials. Electromagnetic energy includes a spectrum of wavelengths including visible light, higher-frequency energy (such as ultraviolet light, X-rays, and Gamma rays), and lower-frequency energy (such as radio waves, microwaves, and infrared radiation). For simplicity, electromagnetic energy of all wavelengths is often referred to as “light.” Materials that undergo a significant change in response to impingement of light are called “photosensitive materials.” 
         [0003]    Existing light-based manufacturing processes include 3D printing, photolithography, and a variety of other processes. These processes are limited in many respects. Many such processes are unable to satisfactorily to produce nanostructures, which may be structures that are smaller than 100 nm. There are many reasons for this, including the quality of the reduction optics used to reduce the size of the illuminated image used for fabrication. Even with high-quality reduction optics, diffraction limitations are still present with many manufacturing methods, and limit the amount of image reduction that can be successfully be carried out. Existing interference lithography techniques may be able to create smaller structures than other techniques, but may be limited to production of periodic patterns. 
         [0004]    In order to create smaller structures such as MEMS (micro-electromechanical systems) devices and high-density integrated circuits, it would be advantageous to provide fabrication systems or methods that overcome the limitations set forth above. 
       SUMMARY 
       [0005]    The present invention may remedy the shortcomings of prior art fabrication methods by providing systems and/or methods for holography-based fabrication. Such fabrication may include, but is not limited to, 3D printing and lithography. Such a system may include a coherent light source, a non-coherent narrow line width source, a monochromatic light source, a hologram, a holographic recording medium, and/or a target such as a reservoir of photosensitive material or a photosensitive material attached to a substrate. 
         [0006]    A hologram of an original object or a lithographic pattern may be recorded on the holographic recording medium through the use of a variety of techniques including but not limited to transmission holography, reflection holography, and Denisyuk holography. All three methods may involve splitting a beam of coherent light from a coherent light source, such as a laser, into two or more beams. The beams may include an object beam that is used to illuminate the original object or lithographic pattern, and a reference beam that illuminates the holographic recording medium. A portion of the object beam may reflect from the original object or lithographic pattern onto the holographic recording medium. The reflected portion of the object beam may cooperate with the reference beam to define an interference pattern that records a hologram of the original object or lithographic pattern in the holographic recording medium. After processing the holographic recording medium, creation of the hologram may be complete. The hologram may then be used in the described process. 
         [0007]    In transmission holography, the reference beam and the reflected portion of the object beam may both impinge against the same side of the holographic recording medium. In reflection holography, the reference beam and the reflected portion of the object beam may impinge against opposite sides of the holographic recording medium. In Denisyuk holography, the holographic recording medium may, itself, be used as a beam splitter that divides the coherent light into the object beam and the reference beam. 
         [0008]    Once the hologram has been recorded and processed, it may be considered an “H1 master hologram” that may be used to fabricate objects and/or create one or more derivative holograms. Specifically, a light source, of a desired wavelength, may be directed at the H1 master hologram to form a holographic image of the original object or lithographic pattern. The holographic image may be positioned in a reservoir of photosensitive material, on a photosensitive material attached to a substrate for lithographic processing, or the like. This may result in the formation of a new object from the photosensitive material, or may facilitate removal or retention of photosensitive material as part of a lithographic process. 
         [0009]    If desired, the holographic image may be made smaller than the original object or lithographic pattern. This may be done by positioning image reduction optics between the H1 master hologram and the photosensitive material. Additionally or alternatively, a second hologram may be formed in a second holographic recording medium by using a coherent light source to illuminate the H1 master hologram to form the holographic image. Light from the holographic image may be used as the object beam. Light that was split off of the coherent light source may be redirected to the second holographic recording medium as a reference beam. Image reduction optics may be positioned between the H1 master hologram and the second holographic recording medium to cause the second hologram to be smaller than the H1 master hologram. The second holographic recording medium may record a hologram that, after processing, defines an “H2 hologram.” The H2 hologram may be illuminated to form a smaller holographic image on the photosensitive material. 
         [0010]    Through the present invention, nanostructures (for example, structures smaller than 100 nm in dimension, although the scope of the present disclosure should not be limited in this regard) may be successfully formed via the application of a hologram to 3D printing and lithographic processing methods. Diffraction limitations of optical systems may be overcome due to the fact that the holographic image may, itself, be generated through diffraction. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0011]      FIG. 1  is a schematic view of a system for recording a holographic image according to one embodiment of the invention. 
           [0012]      FIG. 2  is a flowchart diagram illustrating a method of forming an H1 master hologram according to one embodiment of the invention. 
           [0013]      FIG. 3  is a schematic view of a transmission holographic recording system according to one embodiment of the invention. 
           [0014]      FIG. 4  is a schematic view of a reflection holographic recording system according to another embodiment of the invention. 
           [0015]      FIG. 5  is a schematic view of a Denisyuk holographic recording system according to another embodiment of the invention. 
           [0016]      FIG. 6  is a schematic view of a holographic imaging system according to one embodiment of the invention. 
           [0017]      FIG. 7  is a flowchart diagram illustrating a method for applying holographic imaging to a fabrication process according to the present invention. 
           [0018]      FIG. 8  is a schematic view of a holographic imaging system as applied to 3D printing according to one embodiment of the invention. 
           [0019]      FIG. 9  is a schematic view of a holographic imaging system as applied to 3D printing according to another embodiment of the invention. 
           [0020]      FIG. 10  is a schematic view of an H2 holographic recording system as applied to 3D printing according to another embodiment of the invention. 
           [0021]      FIG. 11  is a schematic view of a holographic imaging system as applied to lithography according to one embodiment of the invention. 
           [0022]      FIG. 12  is a schematic view of an H2 holographic recording system as applied to lithography according to another embodiment of the invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0023]    Various embodiments of the invention will now be described in greater detail in connection with  FIGS. 1-12 . The drawings and associated descriptions are merely exemplary; the scope of the invention is defined not by these, but by the appended claims. 
         [0024]    Referring to  FIG. 1 , a schematic diagram illustrates a system  100  for recording a hologram according to one embodiment of the invention. The system  100  may be designed to record a hologram of an item  110 , which may be a three-dimensional object, a two-dimensional or three-dimensional pattern, or the like. According to certain examples, the item  110  may be an original object that is to be used as a template for producing new objects via 3D printing. According to other examples, the item  110  may be a lithographic pattern that is to be used as a basis for additive or subtractive lithographic processing. In such instances, the item  110  may be an integrated circuit design, an inverse of an integrated circuit design that defines regions between integrated circuit components, or the like. In other embodiments, the item  110  may be used for processes besides 3D printing and lithography, and may be used in other ways than as a manufacturing template. 
         [0025]    The system  100  may have a wide variety of configurations, many of which are known in the holography arts. According to the embodiment shown, the system  100  may include a coherent light source  120 , a beam splitter  122 , redirection optics  124 , and a holographic recording medium  126 . Beam expanding optics such as lenses, microscope objectives, and collimating mirrors and optics may be incorporated into system  100  to acquire the needed beam coverage to record the desired hologram. 
         [0026]    The coherent light source  120  may be any light source designed to emit coherent light (i.e., light of a substantially uniform wavelength and/or frequency). In this application, “light” is not limited to visible light, but may include electromagnetic radiation of any frequency or wavelength. In certain embodiments, the coherent light source  120  may be a laser or the like. The coherent light source  120  may project a first beam  140  of coherent light toward the beam splitter  122 . 
         [0027]    The beam splitter  122  may be designed to receive the first beam  140  and divide the first beam  140  into two components: an object beam  142  and a reference beam  144 . The beam splitter  122  may have any configuration known in the art. If desired, the beam splitter  122  may have the shape of a rectangular prism, which may include two triangular prisms as shown. A portion of the first beam  140  may pass directly through the beam splitter  122  to define the object beam  142 , and the remainder of the first beam  140  may reflect from the interface between the prisms to define the reference beam  144 . The object beam  142  and the reference beam  144  are shown displaced by an angle of 90°, but may be displaced by a variety of different angles in different embodiments. The object beam  142  and/or the reference beam  144  may require the use beam expanding optics such as lenses, microscope objectives and collimating mirrors (not shown). These optics may be incorporated into system  100  to acquire the needed beam coverage to record the desired hologram. 
         [0028]    The reference beam  144  may project toward the redirection optics  124 , which may redirect the reference beam  144  toward a holographic recording medium  126 . The holographic recording medium  126  may or may not be applied to a substrate for support. The redirection optics  124  may include various structures that provide the necessary redirection; in certain embodiments, the redirection optics  124  may include one or more mirrors. In addition to or in the alternative to redirection of the reference beam  144 , the object beam  142  may be redirected through the use of redirection optics (not shown). 
         [0029]    A portion  146  of the object beam  142  may reflect off of the item  110  toward the holographic recording medium  126 . The portion  146  may cooperate with the reference beam  144  to define an interference pattern at the holographic recording medium  126 . The holographic recording medium  126  may be formed of a material that records this interference pattern to record a hologram  160  of the item  110 . 
         [0030]    The holographic recording medium  126  may also be termed a holographic recording film. The holographic recording medium  126  may have any of a variety of compositions known in the art, including but not limited to Silver Halide film, Dichromated gelatin, PMMA, Photosensitive glass, Photosensitive plastic or a variety of photopolymers. The selection of the particular type of holographic recording medium  126  to use may be made based on factors such as the size of the item  110 , the length of the exposure, the required resolution of the hologram  160 , and the like. 
         [0031]    The hologram  160  may be a three-dimensional representation of the item  110 . The holographic recording medium  126 , with the hologram  160  recorded thereon, may be subjected to further processing according to the type of holographic medium used to complete creation of the hologram  160 . The hologram  160  may be an H1 master hologram. The H1 master hologram may be used to project a holographic image of the item  110 , which may, without the use of additional optics, occur at a location that duplicates the original spacing between the item  110  and the holographic recording medium  126  when the hologram  160  was made. 
         [0032]    Referring to  FIG. 2 , a flowchart diagram illustrates a method  200  of forming an H1 master hologram according to one embodiment of the invention. The method  200  may start  210  with a step  220  in which various components are positioned relative to each other in preparation for holographic recording. 
         [0033]    The components referenced in the step  220  may include, but are not limited to, the item  110 , the coherent light source  120 , the beam splitter  122 , the redirection optics  124 , and the holographic recording medium  126  of  FIG. 1 . These various components may advantageously be positioned in a stable arrangement such as on an optical table that is isolated from vibration or other motion. They may also be positioned in dark environment so that only the desired coherent light impinges against the holographic recording medium  126 . 
         [0034]    Once the components have been properly positioned, the method  200  may proceed to a step  230  in which the first beam  140  is projected at the beam splitter  122 , for example, by activating the coherent light source  120 . Then, in a step  240 , the first beam  140  may be divided by the beam splitter  122  into the object beam  142  and the reference beam  144 . 
         [0035]    Then, in a step  250 , the object beam  142  may be projected at the item  110 , for example, by the beam splitter  122 , with or without redirection by elements such as the redirection optics  124 . In a step  260 , the reference beam  144  may be projected at the holographic recording medium  126 , for example, by the beam splitter  122 , with or without redirection by elements such as the redirection optics  124 . In a step  270 , a portion of the object beam  142  may reflect from the item  110  toward the holographic recording medium  126 . 
         [0036]    In response to impingement of the reference beam  144  and the object beam portion  146  on the holographic recording medium  126 , the hologram  160  may be recorded in a step  280 . Then, in a step  290 , the holographic recording medium  126  with the hologram  160  may be processed further to complete formation of the hologram  160 . This processing may be done according to the type of holographic recording medium used. The hologram  160  may then be an H1 master hologram, which may be used in further holography processes as described above. Then, the method  200  may end  298 . 
         [0037]    Referring briefly back to the step  220 , the various components of the system  100  may be positioned in a variety of ways. These may include transmission holography, reflection holography, and Denisyuk holography, which will be shown and described in connection with  FIGS. 3, 4, and 5 , as follows. Those of skill in the art will recognize that these arrangements are merely exemplary, and other arrangements of the components of the system  100  may be used. 
         [0038]    Referring to  FIG. 3 , a schematic view illustrates a transmission holographic recording system, or system  300 , according to one embodiment of the invention. The system  300  may be a subset of the system  100  that is uniquely configured for transmission hologram recording. As shown, the reference beam  144  and the portion  146  of the object beam  142  may impinge against the same side of the holographic recording medium  126 . The reference beam  144  may impinge against the holographic recording medium  126  at a desired angle. As in  FIG. 1 , the reference beam  144  and the portion  146  of the object beam  142  may cooperate to define an interference pattern, which may cause the hologram  160  to be recorded in the holographic recording medium  126 . 
         [0039]    Referring to  FIG. 4 , a schematic view illustrates a reflection holographic recording system, or system  400 , according to another embodiment of the invention. The system  400  may be a subset of the system  100  that is uniquely configured for reflection hologram recording. As shown, the reference beam  144  and the portion  146  of the object beam  142  may impinge against different sides of the holographic recording medium  126 . The sides of the holographic recording medium  126  that receive the reference beam  144  and the portion  146  of the object beam  142  may face in directions that are substantially opposite to each other. The reference beam  144  may again impinge against the holographic recording medium  126  at a desired angle. The reference beam  144  and the portion  146  of the object beam  142  may intersect the holographic recording medium  126  and may cooperate to define an interference pattern, which may cause the hologram  160  to be recorded in the holographic recording medium  126 . 
         [0040]    Referring to  FIG. 5 , a schematic view illustrates a Denisyuk holographic recording system, or system  500 , according to another embodiment of the invention. The system  500  may be a subset of the system  100  that is uniquely configured for Denisyuk hologram recording. As shown, the holographic recording medium  126  may act as a beam splitter. Thus, the beam splitter  122  may be omitted from the system  100 . 
         [0041]    The first beam  140  may impinge directly against the holographic recording medium  126  at a desired angle. The holographic recording medium  126  may receive a portion of the first beam  140  as a reference beam, and may allow transmission of the object beam  142  through the holographic recording medium  126  at the item  110 . The portion  146  of the object beam  142  may reflect from the item  110  to the holographic recording medium  126 . The reference beam and the portion  146  of the object beam  142  may intersect the holographic recording medium  126  and may cooperate to define an interference pattern, which may cause the hologram  160  to be recorded in the holographic recording medium  126 . 
         [0042]    As set forth above, the hologram  160  may be recorded on the holographic recording medium  126  in a wide variety of ways. After the hologram  160  has been recorded and processed, the resulting H1 master hologram may be used to project holographic images. One way in which this may be accomplished will be shown and described in connection with  FIG. 6 . 
         [0043]    Referring to  FIG. 6 , a schematic view illustrates a transmission holographic imaging system, or system  600 , according to one embodiment of the invention. The system  600  may be used to project a holographic image  610  from the H1 master hologram. The holographic image  610  may resemble the item  110 , and may thus have a shape similar to a shape of the item  110 . The holographic image  610  may not include all of the item  110 ; for example, only the portions of the item  110  that were illuminated with coherent light that was reflected to the holographic recording medium  126  (i.e., the portion  146  of the object beam  142 ) may be part of the hologram  160 . Thus, the holographic image  610  may include only such portions of the item  110 . 
         [0044]    The holographic image  610  may be initiated by projecting a beam  620  of coherent light at the H1 master hologram, i.e., at the H1 hologram  160  recorded on the holographic recording medium  126 . Notably, the beam  620  need not necessarily be coherent light, since no interference pattern is being created. Thus, the light source used to illuminate the hologram  160  may be, but is not required to be, a coherent light source such as a laser. Rather, the coherent light source may instead be a single or narrow line source or even a monochromatic light source that is not coherent. 
         [0045]    The beam  620  may be projected at a selected angle, which may be the Bragg angle applicable to the H1 master hologram. This may be the angle at which the reference beam  144  impinged against the holographic recording medium  126  when the hologram  160  was formed. Additionally, the beam  620  may be composed of coherent light with the same wavelength and/or frequency as that originally used to form the hologram  160 . Thus, the coherent light source  120  that was used to form the hologram  160  may advantageously be used to provide the beam  620  of coherent light. 
         [0046]    In response to impingement of the beam  620  of coherent light on the hologram 160 , the item  110  may be optically imaged, in space, at the same location, relative to the holographic recording medium  126 , where it was positioned at the time the hologram 160  was formed. This holographic image may be created by diffraction and formed in open space. 
         [0047]    The holographic image  610  may be projected at any of a variety of locations. According to the present invention, it may be beneficial to project the holographic image  610  on a photosensitive material. A “photosensitive material” is a material that undergoes a significant change in response to impingement of light. The change that occurs in response to impingement of light may be any of many possibilities, including but not limited to the material becoming solid, gaseous, transparent, opaque, harder, softer, more susceptible to further processing, or less susceptible to further processing. Additionally or alternatively, an index of refraction of the material may change, either upward or downward in response to impingement of the light. 
         [0048]    Notably, the change effected by light may not fully be realized without additional processing such as exposure to other substances that, in combination with impingement of the light, enable the full extent of the desired change. Such additional processing may be carried out before, after, or synchronously with Impingement of the light. 
         [0049]      FIG. 6  illustrates transmission holographic imaging, which may be, for example, formed via transmission of the beam  620  through the hologram  160  as shown in  FIG. 6 . Other holographic imaging methods may be used within the scope of the present invention, including but not limited to reflection holograms. Reflection holograms may be made by projecting a beam, such as the beam  620  of  FIG. 6 , at the same side of the H1 master hologram that faces the location of the holographic image. The light may impinge on the hologram  160 , and may then diffract the light in reflection mode to form a holographic image such as the holographic image  610  of  FIG. 6 . 
         [0050]      FIGS. 8-12  also generally illustrate transmission holographic imaging. In alternative embodiments, the methods carried out in any of  FIGS. 8-12  may instead be accomplished through the use of a reflection hologram or other holographic imaging techniques. 
         [0051]    Referring to  FIG. 7 , a flowchart diagram illustrates a method  700  for applying holographic imaging to a fabrication process according to the present invention. The method  700  is generalized, and thus applies to a wide variety of processes including but not limited to 3D printing and lithography. 
         [0052]    The holographic image  610  may be substantially the same size as the item  110 . Alternatively, if desired, the holographic image  610  may be smaller than the item  110 . In the event that the holographic image  610  is to be used for fabrication of nanostructures (for example, via 3D printing or lithography), the holographic image  610  may advantageously be several orders of magnitude smaller than the item  110 . 
         [0053]    Thus, the method  700  may include one or more optional image reduction steps; such steps may be omitted if there is no need to reduce the size of the process that occurs relative to that of the original item. Alternatively, in the event that further reduction of the process, relative to the item, is needed, such image reduction steps may be repeated. More specifically, the step  720 , the step  730 , the step  740 , and/or the step  750  may be carried out for image reduction purposes, and may be omitted or repeated as desired. Additionally, the step  780  may also optionally incorporate image reduction. 
         [0054]    The method  700  may start  710  with a step  720  in which the components are positioned relative to each other. In this step, the components to be positioned may include the coherent light source  120  (or a different coherent light source), the H1 master hologram, image reduction optics (such as lenses, mirrors, and/or the like), and a second holographic recording medium. These components will be shown and described subsequently in connection with the 3D printing and lithography examples mentioned previously. 
         [0055]    As in the step  220 , the step  720  may advantageously include secure fixation of the various components relative to each other in an environment that provides isolation from vibration or other outside motion. Additionally, ambient light may be reduced or eliminated. The coherent light source  120  or other coherent light source may be aimed at the H1 master hologram. If desired, redirection optics such as the redirection optics  124  may be positioned to cause coherent light emitted by the coherent light source  120  or other coherent light source to impinge against the H1 master hologram. The image reduction optics may be positioned between the H1 master hologram and the second holographic recording medium. 
         [0056]    The method  700  may then proceed to a step  730  in which the H1 master hologram is illuminated with coherent light. This may entail activation of the coherent light source  120  and/or other coherent light source. In the event that a coherent light source other than the coherent light source  120  used to form the hologram  160  is used, it may beneficially emit coherent light with the same wavelength and/or frequency as that emitted by the coherent light source  120 . The coherent light may impinge against the H1 master hologram. 
         [0057]    In responses to impingement of the coherent light against the H1 master hologram, a step  740  may occur, in which a holographic image is projected from the H1 master hologram through the image reduction optics and at the second holographic recording medium. The image reduction optics may be positioned between the H1 master hologram and the second holographic recording medium. Thus, as the holographic image is projected at the second holographic recording medium, it may be reduced in size so that, at the second holographic recording medium, it is much smaller than the item  110 . 
         [0058]    In response to projection of the holographic image on the second holographic recording medium, the method  700  may proceed to a step  750  in which the holographic image projected from the H1 master hologram is recorded as a second hologram in the second holographic recording medium. The second hologram may be smaller than the hologram  160  that was originally created from the item  110 . Depending on the reduction power of the reduction optics used, the second hologram may be orders of magnitude smaller than the hologram  160 . After the appropriate processing of the second hologram and the second holographic recording medium in a step  755 , the second hologram may be ready for use as an H2 hologram, as mentioned above. 
         [0059]    In the event that the H2 hologram is not sufficiently small, the step  720 , the step  730 , the step  740 , the step  750 , and/or the step  755  may be performed again, substituting the new H2 hologram for the H1 master hologram, and substituting a third holographic recording medium for the second holographic recording medium. 
         [0060]    More specifically, the H2 hologram, the image reduction optics, the third holographic recording medium, and the coherent light source  120  (or other coherent light source) may all be positioned relative to each other. The image reduction optics used may be the same as those that were used in the original performance of the step  720 , the step  730 , the step  740 , and the step  750 . Additionally or alternatively, different image reduction optics may be used, and may be positioned between and/or relative to the H2 hologram and the third holographic recording medium. 
         [0061]    Then, the H2 hologram may be illuminated with coherent light. A holographic image may be projected from the H2 hologram, through the image reduction optics, and at the third holographic recording medium. A third hologram may be recorded by the holographic image in the third holographic recording medium. The third hologram may be smaller than the second hologram. After the appropriate processing, the hologram recorded in the third holographic recording medium may become an H3 hologram. 
         [0062]    In such a manner, the step  720 , the step  730 , the step  740 , the step  750 , and/or the step  755  may be repeated as many times as needed to obtain a holographically recorded image of the desired size. Since each holographic image may be created through diffraction, creation of a reduced holographic image may not be subject to diffraction limitations. 
         [0063]    Once a hologram of the desired scale has been created (e.g., in the holographic recording medium  126 , the second holographic recording medium, or a subsequently-used holographic recording medium), the method  700  may proceed to a step  760  in which the components are positioned in preparation for the step  770 , the step  780 , and the step  790 . The components positioned in the step  760  may include the hologram created in the most recent iteration of the step  755  (i.e., an H2 hologram or a subsequently-created hologram, hereinafter “final hologram”), a light source of the required wavelength(s) (such as the coherent light source  120 ), the photosensitive material, and/or image reduction optics. 
         [0064]    The coherent light source  120  or a non-coherent light source of the required wavelength may be aimed at the final hologram. If desired, redirection optics such as the redirection optics  124  may be positioned to cause coherent light emitted by the coherent light source  120  or a non-coherent light source of the required wavelength to impinge against the hologram. The image reduction optics may be positioned between the final hologram and the photosensitive material. Again, steps may be taken to ensure the stable placement of the components and/or limit the exposure of the components to ambient light. 
         [0065]    Once the components have been properly placed, the method  700  may proceed to a step  770  in which a light source of the required wavelength is used to illuminate the final hologram. This may be done, for example, by activating the coherent light source  120  or non-coherent light source of the required wavelength. In the event that the light source used in this step is not the same as the coherent light source that which was used to record the final image, it may beneficially emit light with the same wavelength and/or frequency as that emitted by the coherent light source that was used to record the final hologram. The light may then illuminate the hologram created in the most recent iteration of the step  755 . 
         [0066]    In response to impingement of the light against the hologram on which the final image has been recorded, a step  780  may occur, in which a holographic image is projected from the hologram at the photosensitive material. Optionally, this may entail projection of the holographic image through the image reduction optics. 
         [0067]    If used in the step  780 , the image reduction optics may be positioned between the final hologram and the photosensitive material. Thus, as the holographic image is projected at the photosensitive material, it may be reduced in size so that, at the photosensitive material, it is smaller than the item  110  and/or the final hologram. 
         [0068]    In response to projection of the holographic image on the photosensitive material, the photosensitive material may undergo a significant change. As mentioned previously, this change may take many different forms, and the photosensitive material may require other processing in order for this change to be fully realized. In one example, the photosensitive material may be retained within a reservoir, and may solidify in response to impingement of the holographic image, thus creating a new three-dimensional object. In another example, the photosensitive material may be located on a substrate, and may be made more or less resistant to further etching steps by impingement of the holographic image, thus causing a lithographic pattern to be imaged on the substrate. 
         [0069]    Once the holographic image has been projected on the photosensitive material, further processing steps may be performed in a step  790 , depending on the type of fabrication process being carried out. For example, if the process is a 3D printing process, projection of the holographic image into a reservoir of photosensitive material may result in the formation of a new object as the photosensitive material that receives the holographic image solidifies in response. 
         [0070]    The step  790  may thus include removal of the new object from the reservoir. If needed, surface treatments such as cleaning, deburring, and/or sanding may be carried out. If the new object includes one or more nanostructures, suitable measures may be taken to locate, protect, and store the nanostructures. 
         [0071]    If the process is a lithographic process, projection of the holographic image on photosensitive material on a substrate may cause the photosensitive material that receives the holographic image to solidify. Additionally or alternatively, the photosensitive material that receives the holographic image may become more or less susceptible to subtractive (i.e., material removal) processes such as etching. Thus, holographic imaging may be used to determine which portion of the photosensitive material is preferentially etched away, or may be used to protect material from removal via etching. According to some embodiments, the holographic image may be used to form a mask from the photosensitive material. The mask may serve to protect an underlying material from a material removal process such as etching. 
         [0072]    According to alternative embodiments, holographic imaging may be used in combination with additive processes such as sputtering or vacuum deposition. The holographic image may be used to form a mask or selective support layer for such additive processing. 
         [0073]    Accordingly, the step  790  may include the performance of a wide variety of steps, including but not limited to subtractive steps such as etching and additive steps such as sputtering or vacuum deposition. Any other steps known in the lithographic arts may be used to continue processing the material supported by the substrate to form an integrated circuit, device, or the like. Again, if one or more nanostructures is formed, suitable steps may be taken to locate, store, and protect the resulting nanostructures. Once the step  790  has been completed, the method  700  may end  798 . 
         [0074]    As mentioned previously, holography may be used according to the present invention to facilitate a wide variety of manufacturing processes.  FIGS. 8-10  illustrate some potential ways to arrange system components (for example, in the step  720  or the step  760 ) to carry out hologram-assisted 3D printing.  FIGS. 11 and 12  illustrate some potential ways to arrange system components (for example, in the step  720  or the step  760 ) to carry out hologram-assisted lithographic processing. 
         [0075]    Referring to  FIG. 8 , a schematic view illustrates a holographic imaging system, or system  800 , as applied to 3D printing according to one embodiment of the invention. The system  800  may include the coherent light source  120  or a non-coherent light source of the required wavelength (not shown in  FIG. 8 ), the hologram, and a reservoir  810  containing photosensitive material  820 . The hologram may be an H1 master hologram, and may thus include the hologram  160  recorded on the holographic recording medium  126 . Alternatively, the hologram may be an H2 hologram, an H3 hologram, or other hologram formed from an H1 master hologram through the use of additional steps as set forth previously. The photosensitive material  820  may be in liquid, gaseous, solid, or amorphous form. In some embodiments, the photosensitive material  820  is in a liquid or gel form and is made to solidify in response to impingement of the light of the holographic image. 
         [0076]      FIG. 8  may represent the manner in which the components are arranged in the step  760  if no image reduction is desired. Thus, the reservoir  810  may be positioned, relative to the hologram, such that the holographic image  610  is projected directly (i.e., without reduction) into the photosensitive material  820  within the reservoir  810 . The holographic image  610  may cause a quantity of the photosensitive material  820  to solidify into the shape of the item  110 . The resulting new object may be substantially the same size as the item  110 . 
         [0077]    The hologram  160  may be the original hologram recorded directly from the item  110 , as illustrated in  FIG. 1 . Thus, the system  800  may represent the arrangement of the components in the step  760  if the step  720 , the step  730 , the step  740 , and the step  750  of the method  700  of  FIG. 7  have been omitted, and no further image reduction is desired. In alternative embodiments, the step  720 , the step  730 , the step  740 , and the step  750  may be performed as described in connection with  FIG. 7 , and then in the step  760 , the components may be positioned substantially as shown in  FIG. 8 , except that in place of the hologram  160  recorded directly from the item  110  (i.e., the H1 master hologram), the hologram with the reduced image (the H2 hologram or another derivative hologram) may be used. 
         [0078]    In order to scale the new object relative to the hologram  160  (or alternatively, the already scaled hologram used in place of the H1 master hologram), image reduction optics (or image expansion optics) may be added. One example of this will be shown and described in connection with  FIG. 9 . 
         [0079]    Referring to  FIG. 9 , a schematic view illustrates a holographic imaging system, or system  900 , as applied to 3D printing according to another embodiment of the invention. As shown, the system  900  may be used to provide a holographic image  910  that is scaled relative to the hologram  160 .  FIG. 9  may provide image reduction so that the holographic image  910  is relatively smaller than the hologram  160 . This may be achieved by projecting the holographic image  910  through image reduction optics  920 , which may include mirrors, lenses, and/or other features that optically reduce the size of the holographic image  910  relative to that of the hologram  160 . 
         [0080]    Depending on the degree of image reduction used, the holographic image  910  may even be one or more orders of magnitude smaller than the item  110  and/or the hologram  160 . If desired, the system  900  may be used to create microstructures and/or nanostructures. Notably, the present invention may be used to create microstructures and/or nanostructures, not just singly, but also in arrays. In the alternative, if desired, the image reduction optics  920  may be replaced with image enlargement optics so that the holographic image  910  is larger than the hologram  160  and/or the item  110 . 
         [0081]    If the holographic image  910  is projected from the hologram  160  formed directly from the item  110 , as illustrated in  FIG. 9 , the system  900  may represent the arrangement of the components in the step  760  if the step  720 , the step  730 , the step  740 , and the step  750  are omitted. As with the previous embodiment, a hologram such as an H2 hologram or another derivative hologram on which a reduced image of the item  110  has been recorded may be substituted for the H1 master hologram if further reduction is desired. 
         [0082]    Referring to  FIG. 10 , a schematic view illustrates a holographic imaging system for creating an imaged reduced H2 hologram, or system  1000 , as applied to 3D printing according to another embodiment of the invention. As shown, the system  1000  may also record a hologram that is smaller than the item  110 . However, in  FIG. 10 , this may be done by recording a reduced hologram  1060  on a second holographic recording medium  1026 , as in step  720 , step  730 , step  740 , and step  750  of  FIG. 7 . 
         [0083]    More specifically, image reduction optics  1020  may be positioned between the H1 master hologram and the second holographic recording medium  1026 . The second holographic recording medium  1026  may be positioned at the desired location with respect to where the holographic image  610  would ordinarily be projected relative to the H1 master hologram. Thus, the beam  620  may illuminate the H1 master hologram to cause projection of the holographic image  610  through the image reduction optics  1020 , which may result in recordation of the reduced hologram  1060  on the second holographic recording medium  1026  to provide an H2 hologram. 
         [0084]    In order to form the H2 hologram, a reference beam  144  may be projected on the second holographic recording medium  1026 . The holographic image  610  from the H1 master hologram may act as the object beam. The object beam and the reference beam  144  may cooperate to define an interference pattern at the second holographic recording medium  1026 . After processing, the reduced hologram  1060  on the second holographic recording medium  1026  may be used as the H2 hologram. 
         [0085]    The H2 hologram may subsequently be used to project a holographic image  1010  smaller than the H1 master hologram. The holographic image  1010  may be used for 3D printing, for example, by positioning the holographic image  1010  within a photosensitive material, such as the reservoir  810  of photosensitive material  820  as in  FIG. 8  or  FIG. 9 . The holographic image  1010  may be projected into the photosensitive material  820  as shown and described in connection with the holographic image  610  of  FIGS. 8 and 9 . The resulting 3D object may be made without further reduction as in  FIG. 8 , or with further reduction through the use of image reduction optics  920  as in  FIG. 9 . 
         [0086]    As mentioned previously, the reduction process embodied in  FIG. 10  may not be diffraction limited since the holographic image that forms the hologram  160  may, itself, be formed by diffraction. Thus, a high level of reduction may be obtained with a single iteration. However, if desired, multiple iterations may be performed, for example, by projecting the holographic image  1010  from the H2 hologram through image reduction optics to record a further reduced hologram on a third holographic recording medium (not shown). After processing, this further reduced hologram may be used as an H3 hologram. 
         [0087]    The systems and methods of the present invention may offer several advantages, as applied to 3D printing. For example, an entire object may be printed at once and/or made layer by layer. Further, smaller object sizes can be achieved due to the fact that diffraction limitations may not limit the reduction of the holographic image. Yet further, with particular reference to the system  1000  of  FIG. 10 , reduction of the holographic image  1010  may be obtained through reduction of the diffracted holographic image as a light source, rather than reduction of the physical image; this may further allow for the formation of smaller objects. 
         [0088]    Referring to  FIG. 11 , a schematic view illustrates a holographic imaging system, or system  1100 , as applied to lithography according to one embodiment of the invention. The system  1100  may include the coherent light source  120  or a non-coherent light source (not shown in  FIG. 11 ), the holographic recording medium  126 , and a substrate  1130  on which a layer of photosensitive material  1140  is positioned. The holographic recording medium  126  may have the hologram  160  recorded thereon as an H1 master hologram. In alternative embodiments, the hologram  160  may be an H2 hologram, an H3 hologram, or a subsequent derivative hologram. The photosensitive material  1140  may be in liquid, gaseous, solid, or amorphous form. In some embodiments, the photosensitive material  1140  is in a solid or gel form. 
         [0089]    The item  110  used to record the hologram  160  may be a lithographic pattern or the like, and may exist in two or three dimensions. The substrate  1130  and adhering structures may be used to form integrated circuits. If desired, the system  1100  of  FIG. 11  may be used to imprint an integrated circuit pattern on the substrate  1130 . Thus, the item  110  used to form the hologram  160  may more specifically be an integrated circuit design, an inverse of an integrated circuit design that defines regions between integrated circuit components, or the like. 
         [0090]      FIG. 11  may represent the manner in which the components are arranged in the step  760  of  FIG. 7  if image reduction is desired between the holographic recording medium  126  and the photosensitive material  1140 . Thus, the substrate  1130  and the photosensitive material  1140  may be positioned, relative to the H1 master hologram, such that a holographic image  1110  is projected through image reduction optics  1120  onto the photosensitive material  1140 . The image reduction optics  1120  may include mirrors, lenses, and/or other features that optically reduce the size of the holographic image  1110  relative to that of the hologram  160 . 
         [0091]    The holographic image  1110  may cause a quantity of the photosensitive material  1140  to become solid, more easily removed, or more resistant to removal as described above. The pattern defined by the holographic image  1110  may match the lithographic pattern of the item  110 . Thus, the holographic image  1110  may define an integrated circuit or the like. 
         [0092]    The hologram  160  may be the original hologram recorded directly from the item  110  (i.e., the H1 master hologram), as illustrated in  FIG. 1 . Thus, the system  1100  may represent the arrangement of the components in the step  760  if the step  720 , the step  730 , the step  740 , and the step  750  of the method  700  of  FIG. 7  have been omitted, and no further image reduction is desired. In alternative embodiments, the step  720 , the step  730 , the step  740 , and the step  750  may be performed as described in connection with  FIG. 7 , and then in the step  760 , the components may be positioned substantially as shown in  FIG. 8 , except that in place of the holographic recording medium  126  with the hologram  160  recorded directly from the item  110 , the holographic recording medium with the reduced image (the H2 hologram, H3 hologram, or subsequent derivative hologram) may be used. 
         [0093]    Depending on the degree of image reduction used, the holographic image  1110  may even be one or more orders of magnitude smaller than the item  110  and/or the hologram  160 . If desired, the system  1100  may be used to create microstructures and/or nanostructures. Notably, the present invention may be used to create microstructures and/or nanostructures, not just singly, but also in arrays. In the alternative, if desired, the image reduction optics  1120  may be replaced with image enlargement optics so that the holographic image  1110  is larger than the hologram  160  and/or the item  110 . 
         [0094]    Referring to  FIG. 12 , a schematic view illustrates a holographic imaging system for creating an image reduced H2 hologram, or system  1200 , as applied to lithography according to another embodiment of the invention. As shown, the system  1200  may also produce a holographic image  1210  that is smaller than the item  110 . However, in  FIG. 12 , this may be done by recording a reduced hologram  1260  on a second holographic recording medium  1226 , as in step  720 , step  730 , step  740 , and step  750  of  FIG. 7 . 
         [0095]    More specifically, image reduction optics  1220  may be positioned between the H1 master hologram and the second holographic recording medium  1226 . The second holographic recording medium  1226  may be positioned at the location with respect to where the holographic image  610  would ordinarily be projected relative to the H1 master hologram. Thus, the beam  620  may illuminate the H1 master hologram to cause projection of the holographic image  610  through the image reduction optics  1220 , which may result in recordation of the reduced hologram  1260  on the second holographic recording medium  1226  to provide an H2 hologram. 
         [0096]    In order to form the H2 hologram, a reference beam  144  may be projected on the second holographic recording medium  1226 . The holographic image  610  from the H1 master hologram may act as the object beam. The object beam and the reference beam  144  may cooperate to define an interference pattern at the second holographic recording medium  1226 . After processing, the reduced hologram  1260  on the second holographic recording medium  1226  may become the H2 hologram. 
         [0097]    The H2 hologram may subsequently be used to project a holographic image  1210  smaller than the H1 master hologram. The holographic image  1210  may be used for lithography, for example, by positioning the holographic image  1210  within a photosensitive material, such as the photosensitive material  1140  on the substrate  1130  as in  FIG. 11 . The holographic image  1210  may be projected into the photosensitive material  1140  as shown and described in connection with the holographic image  1110  of  FIG. 11 . The resulting lithographic pattern may be made without further reduction, or with further reduction through the use of image reduction optics  1120  as in  FIG. 11 . 
         [0098]    As mentioned previously, the reduction process embodied in  FIG. 12  may not be diffraction limited since the holographic image that forms the reduced hologram  1260  may, itself, be formed by diffraction. Thus, a high level of reduction may be obtained with a single iteration. However, if desired, multiple iterations may be performed, for example, by projecting a holographic image  1210  from the H2 hologram through image reduction optics to record a further reduced hologram on a third holographic recording medium (not shown). After processing, this further reduced image may become an H3 hologram. 
         [0099]    The systems and methods of the present invention may offer several advantages, as applied to lithography. For example, an entire wafer may be printed at once, i.e., in a single exposure. Further, smaller object sizes can be achieved due to the fact that diffraction limitations may not limit the reduction of the holographic image. Yet further, with particular reference to the system  1200  of  FIG. 12 , reduction of the holographic image  1210  may be obtained through reduction of the diffracted holographic image as a light source, rather than reduction of the physical image; this may further allow for the formation of smaller objects. Hence, small structures such as nanostructures may be lithographically printed. In contrast to known interference lithography techniques, the present invention may permit non-periodic patterns to be lithographically printed.

Technology Category: b