Patent Publication Number: US-2006000494-A1

Title: Self-draining edge wheel system and method

Description:
BACKGROUND  
      1. Field of the Invention  
      The present invention relates to semiconductor fabrication, and more specifically, to a self-draining edge wheel for use in semiconductor wafer processing systems.  
      2. Description of the Related Art  
      Semiconductor wafer fabrication operations are typically performed in a repetitive series of fabrication steps. For example, a series of fabrication steps include implantation, material deposition, photolithography, etching, and planarization. The series repeats until the semiconductor wafer is completely fabricated. However, the repetitive series of fabrication steps can produce residue that can remain on a surface of the semiconductor wafer. Residue includes particulates and other undesirable material that can contaminate the metallization lines and structures of the semiconductor wafer. Exemplary particulates can include, among many others, silica, silicon dust, silicate particulates, slurry residue, and metal flakes.  
      To remove the residue, current semiconductor wafer processing systems include cleaning systems to clean the semiconductor wafers. Specifically, fluid is applied to the semiconductor wafer to wet any residue. Then, the fluid can be removed. However, any structure supporting the wafer at the edge may accumulate the fluid. The accumulated fluid may cause a body of fluid to form at the edge and the structure. Then, the accumulated fluid may recontaminate the semiconductor wafer by possibly reintroducing the particulates that were cleaned.  
      Another possible problem may result from the accumulated fluid rewetting a dried semiconductor wafer. Specifically, after the semiconductor wafer has been dried, any accumulated fluid on the structure supporting the semiconductor wafer can reapply fluid to the dried semiconductor wafer. Thus, another operation may be required to completely dry the semiconductor wafer.  
      In view of the foregoing, what is needed is a system and method for preventing the transfer of accumulated fluid on a wafer support structure to semiconductor wafers during a cleaning operation.  
     SUMMARY OF THE INVENTION  
      Broadly speaking, the present invention is a system and method for preventing the transfer of accumulated fluid to semiconductor wafers during a cleaning operation. Specifically, fluid can accumulate at a semiconductor wafer edge. The fluid at the semiconductor wafer edge transfers to a structure, such as an edge wheel supporting the semiconductor wafer edge. By configuring the edge wheel to drain the fluid and thereby prevent fluid accumulation, the fluid does not transfer to the semiconductor wafer being cleaned. It can be appreciated that the present invention can be implemented in numerous ways, such as a process, an apparatus, a system, or a device. Several inventive embodiments of the present invention are described below.  
      In an embodiment of a method for processing a wafer, the method includes supporting a wafer with a plurality of edge wheels positioned peripherally around the wafer. The plurality of edge wheels are capable of rotating so as to rotate the wafer. The method also includes causing a fluid present on a surface of the wafer to move toward the plurality of edge wheels to reach an interface formed between an edge of the wafer and a surface of each of the plurality of edge wheels. Further, the method includes channeling the fluid contacting the plurality of edge wheels away from the interface, such that the channeling of the fluid is configured to prevent formation of a meniscus of the fluid at the interface.  
      In another embodiment of a method for processing a wafer, the method includes supporting a wafer with a plurality of edge wheels positioned peripherally around the wafer. The plurality of edge wheels are capable of rotating so as to rotate the wafer. The method also includes causing a fluid present on a surface of the wafer to move toward the plurality of edge wheels to reach an interface formed between an edge of the wafer and a surface of each of the plurality of edge wheels. Further, the method includes channeling the fluid contacting the plurality of edge wheels away from the interface, such that the channeling of the fluid is configured to prevent formation of a meniscus of the fluid at the interface. The method also includes suctioning the fluid from each of the plurality of edge wheels, such that the suctioning is configured to keep a bottom surface of each of the plurality of edge wheels substantially dry.  
      In an embodiment of an edge wheel for processing a wafer, the edge wheel includes a top portion and a bottom portion forming a groove therebetween for receiving an edge of a wafer. The bottom portion is configured to channel fluid away from the groove to prevent formation of a meniscus of fluid between the groove and the edge of the wafer.  
      An embodiment of a system for processing a wafer includes a plurality of edge wheels for supporting a wafer, such that each of the plurality of edge wheels has a top portion and a bottom portion forming a groove therebetween for receiving an edge of a wafer. The bottom portion is configured to channel fluid away from the groove to prevent formation of a meniscus of fluid between the groove and the edge of the wafer. The system also includes an edge wheel dryer disposed proximate to the plurality of edge wheels, the edge wheel dryer having a plurality of vacuum channels configured to suction fluid away from the bottom portion of each of the plurality of edge wheels.  
      In an embodiment of a method for processing a wafer, the method includes supporting a wafer with a plurality of edge wheels positioned peripherally around the wafer. The method also includes applying a volume of fluid on a surface of the wafer, such that the volume of fluid is sufficient to cause the fluid to move toward the plurality of edge wheels to reach an interface formed between an edge of the wafer and a surface of each of the plurality of edge wheels. Further, the method includes channeling the fluid contacting the plurality of edge wheels away from the interface, such that the channeling of the fluid is configured to prevent formation of a meniscus of the fluid at the interface.  
      In an embodiment of a method for processing a wafer, the method includes supporting a wafer with a plurality of edge wheels positioned peripherally around the wafer. The method also includes applying a volume of fluid on a surface of the wafer, such that the volume of fluid is sufficient to cause the fluid to move toward the plurality of edge wheels to reach an interface formed between an edge of the wafer and a surface of each of the plurality of edge wheels. Further, the method includes channeling the fluid contacting the plurality of edge wheels away from the interface, such that the channeling of the fluid is configured to prevent formation of a meniscus of the fluid at the interface. The method also includes suctioning the fluid from each of the plurality of edge wheels, such that the suctioning is configured to keep a bottom surface of each of the plurality of edge wheels substantially dry.  
      Other aspects of the invention will become apparent from the following detailed description, taken in conjunction with the accompanying drawings, illustrating by way of example the principles of the invention.  
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
      Embodiments of the invention may best be understood by reference to the following description, taken in conjunction with the accompanying drawings, in which:  
       FIG. 1A  is a side view diagram illustrating a cleaning system, in accordance with an embodiment of the invention;  
       FIG. 1B  is a top view diagram illustrating a cleaning system, in accordance with another embodiment of the invention;  
       FIG. 1C  is a top view diagram illustrating a cleaning system, in accordance with yet another embodiment of the invention;  
       FIG. 2A  is a side view diagram illustrating a self-draining edge wheel with an internal chamber, in accordance with an embodiment of the invention;  
       FIG. 2B  is a side view diagram illustrating a self-draining edge wheel with an internal chamber, in accordance with an embodiment of the invention;  
       FIG. 3A  is a side view diagram illustrating a self-draining edge wheel with cut out regions, in accordance with an embodiment of the invention;  
       FIG. 3B  is a bottom view diagram illustrating a self-draining edge wheel with cut out regions, in accordance with an embodiment of the invention;  
       FIG. 4A  is a side view diagram illustrating a self-draining edge wheel having a plurality of legs, in accordance with an embodiment of the invention;  
       FIG. 4B  is a bottom view diagram illustrating a self-draining edge wheel having a plurality of legs, in accordance with an embodiment of the invention;  
       FIG. 5A  is a bottom view diagram illustrating a self-draining edge wheel with angled channels, in accordance with an embodiment of the invention;  
       FIG. 5B  is a side view diagram illustrating a self-draining edge wheel with angled channels, in accordance with an embodiment of the invention;  
       FIG. 6  is a side view diagram illustrating a self-draining edge wheel and a fluid conductor, in accordance with another embodiment of the invention; and  
       FIG. 7  is a flowchart diagram illustrating a method for processing a wafer, in accordance with an embodiment of the invention.  
    
    
     DETAILED DESCRIPTION  
      The following descriptions describe embodiments of a system and method for processing a wafer to prevent the transfer of accumulated fluid to wafers during a cleaning operation. Specifically, multiple self-draining edge wheels support the wafer during the cleaning operation. Fluid on a surface of the wafer propagates to an edge of the wafer. Upon reaching the edge of the wafer, the fluid can accumulate. The accumulated fluid can contact the multiple self-draining edge wheels and cause the accumulated fluid to coat a surface of each of the multiple self-draining edge wheels. Thereafter, the fluid coating drains away from the contact point with the edge of the wafer.  
      The drained fluid can then be suctioned away from the multiple self-draining edge wheels to maintain substantially dry self-draining edge wheels. Otherwise, the drained fluid is removed from the surface of each of the multiple self-draining edge wheels through the self-draining properties of the multiple self-draining edge wheels. It will be obvious, however, to one skilled in the art, that the present invention may be practiced without some or all of these specific details. In other instances, well known process operations have not been described in detail in order not to unnecessarily obscure the present invention.  
      Further, the embodiments described herein are exemplary. It will be appreciated by those skilled in the art that upon reading the description and studying the drawings, various alterations, additions, permutations and equivalents thereof are possible. It is therefore intended that all such alterations, additions, permutations, and equivalents fall within the true spirit and scope of the disclosed embodiments.  
       FIG. 1A  is a side view diagram illustrating a cleaning system  100 , in accordance with an embodiment of the invention. As shown in  FIG. 1A , a wafer  110  is positioned for processing in a cleaning system  100 . In some embodiments, the wafer  110  can have a diameter of a 200 mm or 300 mm. However, one of ordinary skill in the art will recognize that the size of the wafer  110  can vary. In one embodiment, the cleaning system  100  is enclosed in a chamber, as illustrated in  FIG. 1A . However, other embodiments do not use an enclosed cleaning system for performing cleaning operations on wafer  110 . Details regarding an example of a non-enclosed cleaning system will be further described with reference to  FIG. 3C .  
      The cleaning system  100  includes a plurality of self-draining edge wheels (edge wheels)  120 . As illustrated, the edge wheels  120  support the wafer  110  via an interface. Specifically, the interface is formed between a v-like groove of the edge wheels  120  and the wafer  110 . The groove positions the wafer  120  to permit rotation of the wafer  110  and the edge wheel  120 . However, other interfaces with different shapes can couple the wafer  110  and the edge wheel  120 , as long as the other interfaces form when supporting the wafer  110 .  
      The edge wheels  120  are capable of rotating, thus permitting the rotation of the wafer  110 . As the wafer  110  rotates, any fluid on a bottom surface or a top surface of the wafer  110  propagates to an edge of the wafer  110 . The edge of the wafer  1   10  is in contact with each of the edge wheels  120  at the interface. Accordingly, the propagated fluid accumulates on the edge of the wafer  110  and the interface. Specifically, accumulated fluid at a bottom surface  130  and a top surface  135  may form. Each accumulation of fluid may form a meniscus that can contaminate each wafer  110  introduced to the cleaning system  100 . However, fluid channeling from the interface prevents formation of the meniscus.  
      In another embodiment of the present invention, fluid can be applied to the wafer  110  while the wafer is stationary, i.e. not rotating. Here, the volume of fluid applied to the surface of the wafer  110  should be sufficient such that the fluid propagates to the edge of the wafer and the interface. The fluid reaching the interface is channeled away according to the embodiments of the present invention described herein.  
      Fluid channeling occurs because the edge wheels  120  of the present invention are configured to drain fluid from the interface. For example, in an embodiment of an edge wheel  120  having a bottom portion and a top portion, the bottom portion can be configured to drain fluid away from the interface. In another exemplary embodiment, one or more edge wheel dryers  140  can suction the fluid away from the bottom portion of the edge wheels  120  by using one or more vacuum channels. However, it should be appreciated that the edge wheel dryer  140  may or may not be used to suction fluid from the edge wheel  120 . In at least one embodiment of the present invention, the edge wheel  120  is configured to drain fluid without suctioning from an edge wheel dryer  140 .  
       FIG. 1B  is a top view diagram illustrating the cleaning system  100 , in accordance with another embodiment of the invention. The cleaning system  110  can include three edge wheels  120  to support the wafer  110 . As the wafer  110  rotates in a direction  180 , each of the edge wheels  120  rotate in a direction  190 . Further, each edge wheel  120  is illustrated coupled to an edge wheel dryer  140 . However, one of ordinary skill will recognize that the inclusion of any edge wheel dryer  140  in  FIG. 1B  is purely exemplary because an edge wheel dryer  140  may or may not be used with an edge wheel  120 . Further, although illustrated with three edge wheels dryers  140 , other embodiments may include one edge wheel dryer  140  suctioning fluid from all three edge wheels  120 . Thus, any configuration of edge wheel dryers  140  and edge wheels  120  is possible, as long as any edge wheel dryer  140  used with at least one edge wheel  120  suctions fluid from at least one edge wheel  120 .  
      At least one edge wheel  120  is coupled to a robotic arm  125 . The robotic arm  125  can move the edge wheel  120  and if necessary, any coupled edge wheel dryer  140  away from the wafer  110 . By moving the edge wheel  120 , the wafer  110  may be moved from or be placed in contact with the grooves of the edge wheels  120 . After positioning the wafer  110  in the grooves, the robotic arm  125  moves the edge wheel  120  back to the wafer  110  to secure the wafer  110 . However, the edge wheel  120  can be coupled to any other type of mechanical appendage, such as the robotic arm  125 , as long as the mechanical appendage can move the edge wheel  120 . Further, it should be appreciated that any method of securing the wafer  110  to the interfaces of the edge wheels  120  is possible, as long as the wafer  110  can be secured while permitting rotation.  
       FIG. 1C  is a top view diagram illustrating a cleaning system, in accordance with yet another embodiment of the invention. In an exemplary embodiment of the present invention of performing cleaning operations, a proximity cleaning system  150  can be used to clean and dry the wafer  110 . The proximity cleaning system  150  may include an arm  160  that moves the proximity cleaning system  150  in a cleaning and drying pattern. An exemplary proximity cleaning system  150  is disclosed in U.S. patent application Ser. No. 10/261,839, entitled, “Method and Apparatus for Drying Semiconductor Wafer Surfaces Using a Plurality of Inlets and Outlets Held in Close Proximity to the Wafer Surfaces,” and filed on Sep. 30, 2002, the disclosure of which is incorporated by reference in its entirety. One of ordinary skill in the art will appreciate that any suitable configuration of the proximity cleaning system  150  is possible, as long as the proximity cleaning system  150  applies fluid to the wafer  110  that is drained according to the method of the present invention.  
      The cleaning system of  FIG. 1C  illustrates four edge wheels  120  coupled to four edge wheel dryers  140 . As illustrated, the robotic arm  125  can move away in a direction  127  to permit the positioning of the wafer  110 . Further, another robotic arm  125 ′ coupled to the edge wheel dryer  140  can move in a direction  147 . Thus, other embodiments can include any number of robotic arms to move any edge wheel  120  or edge wheel dryer  140 .  
       FIG. 2A  is a side view diagram illustrating a self-draining edge wheel with an internal chamber  230 , in accordance with an embodiment of the invention. The edge wheel  120  supports the wafer  110  at an interface. When the wafer  110  is positioned in the groove, fluid at the interface is channeled into edge wheel openings  205 . The edge wheel openings  205  channel the fluid from the interface into the internal chamber  230 . Thus, as the edge wheel  120  rotates, the edge wheel openings  205  prevent fluid from accumulating at the interface by permitting the fluid to drain into the internal chamber  230 . Consequently, no fluid transfer occurs from the interface to subsequent wafers  110  positioned for cleaning.  
      If an edge wheel dryer  140  is used to suction fluid from the internal chamber  230 , then an exemplary edge wheel dryer  140  can include a plurality of vacuum channels. For example, an upper vacuum channel  270  can suction fluid away from the groove. Further, a lower vacuum channel  260  can suction fluid from the internal chamber  230 . Specifically, a vacuum port  240  can be inserted into a drain  220  of the edge wheel dryer  120 . The drain  220  forms a circular channel in the bottom portion of the edge wheel  120  in which the vacuum port  240  is inserted. The vacuum port  240  is sufficiently fitted to the drain  220  to prevent fluid from escaping the suctioning of the fluid into the lower vacuum channel  260 . By preventing the fluid from escaping the suction applied from the lower vacuum channel  260 , the bottom surface of the edge wheel  120  is kept substantially dry. It should be appreciated that any number of vacuum channels are possible. For example, the upper vacuum channel  270  may be excluded from the edge wheel dryer  140 . It should further be appreciated that if there is more than one vacuum channel in an edge wheel dryer  140 , any combination of functioning vacuum channels can be employed. For example, the lower vacuum channel  260  can suction fluid while the upper vacuum channel  270  remains inoperative.  
       FIG. 2B  is a side view diagram illustrating a self-draining edge wheel with an internal chamber, in accordance with an embodiment of the invention. The edge wheel openings  205  can have any shape or size. Although illustrated as circular openings on the edge wheel  120 , the edge wheel openings  205  can have any suitable shape. The edge wheel openings  205  can also have varying sizes, as long as the sizes of the edge wheel openings  205  permit the fluid to drain into the internal chamber  230 . The internal chamber  230  includes a drain to remove fluid from the edge wheel  120 . Thus, without using the edge wheel dryer  140 , fluid channeled to the internal chamber  230  can be removed.  
      In addition, there can be any number of edge wheel openings  205  having varying spaces between each edge wheel opening  205 . In yet another embodiment, the edge wheel openings  205  can be positioned in multiple rows. For example, there can be two or more rows of each edge wheel openings  205  to permit fluid channeling from the interface formed by the groove and the wafer  110 .  
       FIG. 3A  is a side view diagram illustrating a self-draining edge wheel with cut out regions  310 , in accordance with an embodiment of the invention. Similar to previous embodiments, the edge wheel dryer  140  may or not be used with the edge wheel  120 . Here, the edge wheel  120  is composed of a top portion  320  and a bottom portion  330 . The top portion  320  and the bottom portion  330  can be manufactured from a single block of material or can be manufactured from two separate blocks of material. If manufactured from two separate blocks, then the top portion  320  and the bottom portion  330  can be coupled together to form the interface that supports the wafer  110 . The material can be polyurethane or other similar material. However, any suitable material may be used, as long as the material is a sufficiently rigid material that can support the wafer  110 . Further, the material should not generate particles that may contaminate the wafer  110  during the cleaning operation.  
      In selecting a material for the edge wheel  120 , the ability of the material to attract or repel fluid can be considered. The property of a material&#39;s ability to attract or repel fluid is the philicity or phobicity of the material, respectively. For example, the fluid, which can include water, deionized water (DIW), a chemistry, a combination of the chemistry and DIW, and a combination of the chemistry and water may be attracted to or repelled from a particular material. It should be appreciated that any suitable fluid and suitable material used in wafer processing systems is possible, as long as the fluid is drained according to the method of the present invention. Thus, when selecting the material, the property of whether the material attracts or repels a particular fluid can be considered during the selection.  
      The bottom portion  330  of the edge wheel  120  does not have an internal chamber  230 , but instead has multiple cut out regions  310 . The cut out regions  310  enable fluid to drain towards the bottom surface of the edge wheel  120 , thereby preventing the accumulation of fluid at the interface. Specifically,  FIG. 3B  is a bottom view diagram illustrating a self-draining edge wheel with cut out regions, in accordance with an embodiment of the invention. The cut out regions  310  channel fluid from the interface to the bottom surface of the edge wheel  120  during the rotation of the edge wheel. During rotation, the edge wheel dryer  140  can suction the fluid draining towards the bottom surface of the edge wheel  120 . In particular, by positioning a lower vacuum channel opening  340  to encompass the fluid draining from the interface, the fluid can be suctioned away from the bottom surface of the edge wheel  120 .  
       FIG. 4A  is a side view diagram illustrating a self-draining edge wheel having a plurality of legs, in accordance with an embodiment of the invention. The edge wheel  120  of another embodiment includes a top portion  420  coupled to multiple legs  410 . The legs  410  can be manufactured independently of the top portion  420  and can be attached to the top portion  420  via various means. For example, the legs  410  can be screwed into a bottom surface of the top portion  420 . The legs  410  are separated by spaces for fluid channeling. As the edge wheel  120  rotates, fluid at the interface drains via the spaces to the bottom surface of the edge wheel  120 . Any fluid channeled away from the interface is spun off the bottom surface of the edge wheel  120 , thus maintaining a substantially dry bottom surface of the edge wheel  120 .  
      However, if the edge wheel dryer  140  is positioned proximately adjacent to the edge wheel  120 , then the edge wheel dryer  140  can suction fluid from the edge wheel  120 . For example, the lower vacuum channel  260  can be positioned to suction fluid from the bottom surface of the edge wheel  120  by positioning the lower vacuum channel  260  to encompass fluid spun off the edge wheel  120 . Although illustrated with one lower vacuum channel opening  430 , the lower vacuum channel  260  can include another lower vacuum channel opening (not shown). Thus, multiple lower vacuum channel openings can suction fluid from various locations of the bottom surface of the edge wheel  120 .  
       FIG. 4B  is a bottom view diagram illustrating a self-draining edge wheel having a plurality of coupled legs, in accordance with an embodiment of the invention. In another embodiment of the edge wheel dryer  140  (not shown), the lower vacuum channel  260  can extend along the diameter of the bottom surface of the edge wheel  120 . Along the length of the lower vacuum channel  260 , multiple lower vacuum channel openings suction fluid. Alternatively, one sufficiently large lower vacuum channel opening having sufficient suctioning capability can suction fluid from the bottom surface of the edge wheel  120 . Thus, the embodiment of the edge wheel  120  of  FIG. 4B  can have a substantially dry bottom surface.  
       FIG. 5A  is a bottom view diagram illustrating a self-draining edge wheel with angled channels  520 , in accordance with an embodiment of the invention. The edge wheel  120  includes a bottom portion configuration having multiple projections  510  and angled channels  520 . Specifically, the projections  510  and the top portion can be manufactured from one material or from various materials. For example, the bottom portion can be coupled to the top portion to form the interface. The angled channels  520  enhance fluid channeling from the interface.  FIG. 5B  is a side view diagram illustrating the self-draining edge wheel with angled channels  520 , in accordance with an embodiment of the invention. Specifically, as fluid contacts the interface, the angled channels  520  enhance fluid flow away from the interface by providing a single point from which the fluid drains. Thus, the angled channels  520  prevent the formation of the meniscus of the fluid at the interface.  
      The embodiment illustrated in  FIG. 5B  may or may not include an edge wheel dryer  140 . If using an edge wheel dryer  140  to suction fluid from the bottom surface of the edge wheel  120 , then one of ordinary skill in the art will recognize that the edge wheel dryer  140  can have configurations similar to the previously described embodiments.  
       FIG. 6  is a side view diagram illustrating a self-draining edge wheel and a fluid conductor  610 , in accordance with another embodiment of the invention. The fluid conductor  610  is coupled to the bottom portion of the edge wheel  120  at a center location (not shown). By providing a space beneath the bottom surface of the edge wheel  120 , fluid channeled from the interface can flow along the edges  620  of the fluid conductor  610 . Specifically, the fluid conductor  610  guides fluid draining from the edge wheel  120  away from the bottom surface of the edge wheel  120 . Further, if the edge wheel dryer  140  is positioned to suction fluid flowing along the edges  620  using the lower vacuum channel  260 , then the fluid conductor  610  guides any fluid not suctioned by the lower vacuum channel  260  away from the bottom surface of the edge wheel  120 . Thus, the bottom surface of the edge wheel  120  is kept substantially dry.  
       FIG. 7  is a flowchart diagram illustrating a method for processing a wafer, in accordance with an embodiment of the invention. The method begins in operation  710  when a mechanism such as a robotic arm positions a wafer to be supported by wheels. Specifically, the wafer is positioned to perform a cleaning operation that cleans a surface the wafer. Positioning the wafer includes a manipulation of the wheel to enable an edge of the wafer to contact a groove of the wheel. Thus, an interface forms at the contact point. In exemplary embodiments, one or both surfaces of the wafer can be cleaned. For example, fluid can be applied to a top surface and a bottom surface of the wafer. Examples of methods to apply fluid include using a proximity cleaning system, spraying mechanisms, and immersion techniques. In other exemplary embodiments, the wafer does not require the application of fluid because the fluid is present on the surface of the wafer when positioned for cleaning. Then, in operation  720 , the method includes operations to rotate the wafer. Specifically, as the wafer rotates, the wheels supporting the wafer rotate. During rotation of the wafer, any fluid on a surface of the wafer propagates to the edge of the wafer.  
      In another embodiment of the present invention, the wafer remains stationary, i.e. not rotating. Further, the wheels may remain stationary. Thus, fluid applied to the surface of the stationary wafer propagates to the edge of the wafer because the volume of the applied fluid sufficiently covers the surface area of the wafer. It should be appreciated that in another embodiment, the wheels may rotate to permit movement of the wafer. However, rotation is not required to propagate fluid to the edge of the wafer.  
      Next, in operation  730 , the method includes operations to channel fluid from an interface. Specifically, the fluid propagated to the edge of the wafer does not accumulate to form a body of fluid having a meniscus. To prevent fluid accumulation, the fluid is channeled away from the interface. Fluid channeling occurs through a combination of a structure of a bottom portion of the wheels and the material composition of the wheels. For example, the structure of the bottom portion can include an internal chamber having openings for draining fluid, cut out regions, a plurality of coupled legs, and angled channels. The structure also includes any of the structures of the embodiments previously described. Further, the material composition of the wheels can consider the phobicity, philicity, and hardness of the material.  
      Thereafter, in operation  740 , the method includes positioning an edge wheel proximately adjacent to the wheels to apply suction to remove fluid from the wheels. It should be appreciated that embodiments of the present invention may or may not apply an edge wheel dryer. Further, the edge wheel dryer can be configured according to the previous embodiments previously described. When using the edge wheel dryer, a vacuum positioned near the bottom portion of the wheels can suction fluid channeled from the interface. Thus, the bottom surface of the wheels remains substantially dry.  
      To those of ordinary skill in the art, the operations described herein, and illustrated by the drawings, are exemplary. Further, the operations can be performed in any order to permit the draining of fluid from the wheels. Thus, the order of the operations is not limited to any particular sequence.  
      Although the foregoing invention has been described in some detail for purposes of clarity of understanding, it will be apparent that certain changes and modifications can be practiced within the scope of the appended claims. Accordingly, the present embodiments are to be considered as illustrative and not restrictive, and the invention is not to be limited to the details given herein, but may be modified within the scope and equivalents of the appended claims.