Abstract:
A system and method of forming and using a proximity head. The proximity head includes a head surface, the head surface including a first zone, a second zone and an inner return zone. The first zone including a first flat surface region and a plurality of first discrete holes. Each one of the plurality of first discrete holes being connected to a corresponding one of a plurality of first conduits. The plurality of first discrete holes residing in the head surface and extending through the first flat surface region. At least a portion of the plurality of first discrete holes are arranged in a first row. The second zone including a second flat region and a plurality of second discrete holes. Each one of the plurality of second discrete holes being connected to a corresponding one of a plurality of second conduits. The plurality of second discrete holes residing in the head surface and extending through the second flat surface region. The inner return zone including a plurality of inner return discrete holes. The inner return zone being disposed between and adjacent to the first zone and the second zone. Each one of the plurality of the inner return discrete holes being connected to a corresponding one of a plurality of inner return conduits. The plurality of inner return discrete holes residing in the head surface and extending through the head surface. At least a portion of the plurality of inner return discrete, holes are arranged in an inner return row. The first row and the inner return row being substantially parallel. A first portion of an edge of each one of the plurality of inner return discrete holes is recessed into the head surface.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is related to co-pending and co-owned U.S. patent application Ser. No. 10/611,140, Attorney Docket number LAM2P429, filed on Jun. 30, 2003 and entitled “METHOD AND APPARATUS FOR CLEANING A SUBSTRATE USING MEGASONIC POWER,” which is incorporated herein by reference in its entirety for all purposes. This application is related to co-pending and co-owned U.S. patent application Ser. No. 10/330,843, Attorney Docket number LAM2P381A, filed on Dec. 24, 2002 and entitled “MENISCUS, VACUUM, IPA VAPOR, DRYING MANIFOLD,” which is incorporated herein by reference in its entirety for all purposes. This application is also related to co-pending and co-owned U.S. patent application Ser. No. 10/330,897, Attorney Docket number LAM2P381B, filed on Dec. 24, 2002 and entitled “SYSTEM FOR SUBSTRATE PROCESSING WITH MENISCUS, VACUUM, IPA VAPOR, DRYING MANIFOLD,” which is incorporated herein by reference in its entirety for all purposes. This application is also related to co-pending and co-owned U.S. patent application Ser. No. 10/261,839, Attorney Docket number LAM2P191.CIP, filed on Sep. 30, 2002 and entitled “METHOD AND APPARATUS FOR DRYING SEMICONDUCTOR WAFER SURFACES USING A PLURALITY OF INLETS AND OUTLES HELD IN CLOSE PROXIMITY TO THE WAFER SURFACES,” which is incorporated herein by reference in its entirety for all purposes. 
       BACKGROUND 
       [0002]    The present invention relates generally to semiconductor manufacturing processes, and more particularly, to methods and systems for processing semiconductors with a proximity head. 
         [0003]    In the semiconductor chip fabrication process, it is well-known that there is a need to clean and dry a wafer where a fabrication operation has been performed that leaves unwanted residues on the surfaces of wafers. Examples of such a fabrication operation include plasma etching and chemical mechanical polishing (CMP). In CMP, a wafer is placed in a holder that pushes a wafer surface against a polishing surface. Slurry can include chemicals and abrasive materials to cause the polishing. Unfortunately, this process tends to leave an accumulation of slurry particles and residues at the wafer surface. If left on the wafer, the unwanted residual material and particles may cause, among other things, defects such as scratches on the wafer surface and inappropriate interactions between metallization features. In some cases, such defects may cause devices on the wafer to become inoperable. In order to avoid the undue costs of discarding wafers having inoperable devices, it is therefore necessary to clean the wafer adequately yet efficiently after fabrication operations that leave unwanted residues. 
         [0004]    After a wafer has been wet cleaned, the wafer must be dried effectively to prevent water or cleaning fluid remnants from leaving residues on the wafer. If the cleaning fluid on the wafer surface is allowed to evaporate, as usually happens when droplets form, residues or contaminants previously dissolved in the cleaning fluid will remain on the wafer surface after evaporation (e.g., and form spots). To prevent evaporation from taking place, the cleaning fluid must be removed as quickly as possible without the formation of droplets on the wafer surface. 
         [0005]    In an attempt to accomplish this, one of several different drying techniques is employed, such as spin-drying and the like. These drying techniques utilize some form of a moving liquid/gas interface on a wafer surface that, if properly maintained, results in drying of a wafer surface without the formation of droplets. Unfortunately, if the moving liquid/gas interface breaks down, as often happens with all of the aforementioned drying methods, droplets form and evaporation occurs resulting in contaminants and/or spots being left on the wafer surface. 
         [0006]    In view of the forgoing, there is a need for drying technique that minimizes the effects of droplets on the surface of the substrate or substantially eliminates the formation of droplets on the surface of the substrate. 
       SUMMARY 
       [0007]    Broadly speaking, improved proximity head and a system and method for using the improved proximity head. It should be appreciated that the present invention can be implemented in numerous ways, including as a process, an apparatus, a system, computer readable media, or a device. Several inventive embodiments of the present invention are described below. 
         [0008]    One embodiment provides a proximity head. The proximity head includes a head surface, the head surface including a first zone, a second zone and an inner return zone. The first zone including a first flat surface region and a plurality of first discrete holes. Each one of the plurality of first discrete holes being connected to a corresponding one of a plurality of first conduits. The plurality of first discrete holes residing in the head surface and extending through the first flat surface region. At least a portion of the plurality of first discrete holes are arranged in a first row. The second zone including a second flat region and a plurality of second discrete holes. Each one of the plurality of second discrete holes being connected to a corresponding one of a plurality of second conduits. The plurality of second discrete holes residing in the head surface and extending through the second flat surface region. The inner return zone including a plurality of inner return discrete holes. The inner return zone being disposed between and adjacent to the first zone and the second zone. Each one of the plurality of the inner return discrete holes being connected to a corresponding one of a plurality of inner return conduits. The plurality of inner return discrete holes residing in the head surface and extending through the head surface. At least a portion of the plurality of inner return discrete holes are arranged in an inner return row. The first row and the inner return row being substantially parallel. A first portion of an edge of each one of the plurality of inner return discrete holes is recessed into the head surface. 
         [0009]    The first zone can also include a plurality of third discrete holes, each one of the plurality of third discrete holes being connected to a corresponding one of a plurality of third conduits. The plurality of third discrete holes residing in the head surface and extending through the first flat surface region. At least a portion of the plurality of third discrete holes are arranged in a third row. The third row being substantially parallel to the first row and being disposed on a side of the first row opposing the interface row. 
         [0010]    The plurality of first conduits can be coupled to a first liquid source and configured to provide a first liquid to the head surface. The second conduits can be coupled to a second liquid source and configured to provide a second liquid to the head surface. The plurality of inner return conduits and the plurality of third conduits can be coupled to a vacuum source and configured to remove at least a portion of the first liquid from the head surface. 
         [0011]    The recessed first portion of an edge of each one of the plurality of inner return discrete holes is recessed into the head surface at a first angle, the first angle forms a chamfer extending from the recessed first portion of an edge of each one of the plurality of inner return discrete holes toward the first row for a first distance. 
         [0012]    The recessed first portion of an edge of each one of the plurality of inner return discrete holes can be included in a recessed first angled portion having a first recessed edge at each one of the plurality of inner return discrete holes and the recessed first angled portion including a second recessed edge intersecting the head surface and wherein the recessed first angled portion extends from the inner return row toward the first row for a first distance. 
         [0013]    The recessed first angled portion can include more than one angled portions. The recessed first angled portion can include one or more curved portions. The first recessed edge can include a curved portion from the recessed first angled portion into each one of the plurality of inner return discrete holes. 
         [0014]    At least a portion of the plurality of second discrete holes can be arranged in a second row. The second row and the inner return row being substantially parallel. The second row opposing the first row and wherein the second zone further includes a plurality of fifth discrete holes and plurality of sixth discrete holes. Each one of the plurality of fifth discrete holes being connected to a corresponding one of a plurality of fifth conduits and each one of the plurality of sixth discrete holes being connected to a corresponding one of a plurality of sixth conduits. The plurality of fifth discrete holes and the plurality of sixth discrete holes residing in the head surface and extending through the second flat surface region. At least a portion of the plurality of fifth discrete holes are arranged in a third row and at least a portion of the plurality of sixth discrete holes are arranged in a fifth row. The third row and at least a portion of the fourth row being substantially parallel to the second row. The third row being disposed on a side of the second row opposing the inner return row, the fourth row being disposed on a side of the third row opposing the second row. 
         [0015]    The plurality of first conduits can be coupled to a first liquid source and configured to provide a first liquid to the head surface, the plurality of second conduits are coupled to a second liquid source and configured to provide a second liquid to the head surface, the plurality of inner return conduits and the plurality of fifth conduits being configured to remove at least a portion of the second liquid from the head surface, the plurality of sixth conduits being configured to provide a first fluid to the head surface, the first fluid being different than the first liquid and the second liquid. 
         [0016]    The second zone can include a protrusion having an angled surface. The angled surface having a first edge and the first edge intersecting the head surface between the second row and the inner return row. The angled surface having a second edge proximate to the inner return row. The second edge protruding from the head surface a protruding distance less than a distance between the head surface and a surface to be processed. The angled surface can intersect the head surface at an angle of between about 1 degree and about 89 degrees. The angled surface can include more. than one angled surface. At least one of the more than one angled surface is substantially parallel to the head surface. 
         [0017]    At least a portion of the plurality of second conduits can intersect the head surface at an angle of between about 10 degrees and about 90 degrees and directed toward the inner return row. At least a portion of at least one of the first flat surface region and the second flat surface region can be curved. 
         [0018]    Another embodiment provides a proximity head. The proximity head including a head surface, the head surface including a first zone, a second zone and an inner return zone. The first zone including a first flat surface region and a plurality of first discrete holes. Each one of the plurality of first discrete holes being connected to a corresponding one of a plurality of first conduits. The plurality of first discrete holes residing in the head surface and extending through the first flat surface region. At least a portion of the plurality of first discrete holes are arranged in a first row. The second zone including a second flat region and a plurality of second discrete holes. Each one of the plurality of second discrete holes being connected to a corresponding one of a plurality of second conduits. The plurality of second discrete holes residing in the head surface and extending through the second flat surface region. The inner return zone including a plurality of inner return discrete holes. The inner return zone being disposed between and adjacent to the first zone and the second zone. Each one of the plurality of the inner return discrete holes being connected to a corresponding one of a plurality of inner return conduits. The plurality of inner return discrete holes residing in the head surface and extending through the head surface. At least a portion of the plurality of inner return discrete holes are arranged in an inner return row. The first row and the inner return row being substantially parallel. The second zone includes a protrusion having an angled surface, the angled surface having a first edge, the first edge intersecting the head surface between the second row and the inner return row, the angled surface having a second edge proximate to the inner return row, the second edge protruding from the head surface a protruding distance less than a distance between the head surface and a surface to be processed. 
         [0019]    Another embodiment provides a proximity head. The proximity head including a head surface, the head surface including a first zone, a second zone and an inner return zone. The first zone including a first flat surface region and a plurality of first discrete holes. Each one of the plurality of first discrete holes being connected to a corresponding one of a plurality of first conduits. The plurality of first discrete holes residing in the head surface and extending through the first flat surface region. At least a portion of the plurality of first discrete holes are arranged in a first row. The second zone including a second flat region and a plurality of second discrete holes. Each one of the plurality of second discrete holes being connected to a corresponding one of a plurality of second conduits. The plurality of second discrete holes residing in the head surface and extending through the second flat surface region. The inner return zone including a plurality of inner return discrete holes. The inner return zone being disposed between and adjacent to the first zone and the second zone. Each one of the plurality of the inner return discrete holes being connected to a corresponding one of a plurality of inner return conduits. The plurality of inner return discrete holes residing in the head surface and extending through the head surface, at least a portion of the plurality of inner return discrete holes are arranged in an inner return row. The first row and the inner return row being substantially parallel. At least a portion of the plurality of second conduits intersect the head surface at an angle of between about 10 degrees and about 90 degrees and directed toward the inner return row. 
         [0020]    Yet another embodiment provides a proximity head. The proximity head including a head surface, the head surface including a first zone, a second zone and an inner return zone. The first zone including a first flat surface region and a plurality of first discrete holes. Each one of the plurality of first discrete holes being connected to a corresponding one of a plurality of first conduits. The plurality of first discrete holes residing in the head surface and extending through the first flat surface region. At least a portion of the plurality of first discrete holes are arranged in a first row. The second zone including a second flat region and a plurality of second discrete holes. Each one of the plurality of second discrete holes being connected to a corresponding one of a plurality of second conduits. The plurality of second discrete holes residing in the head surface and extending through the second flat surface region. The inner return zone including a plurality of inner return discrete holes. The inner return zone being disposed between and adjacent to the first zone and the second zone. Each one of the plurality of the inner return discrete holes being connected to a corresponding one of a plurality of inner return conduits. The plurality of inner return discrete holes residing in the head surface and extending through the head surface. At least a portion of the plurality of inner return discrete holes are arranged in an inner return row. The first row and the inner return row being substantially parallel. A first portion of an edge of each one of the plurality of inner return discrete holes is recessed into the head surface and the second zone includes a protrusion having an angled surface. The angled surface having a first edge and the first edge intersecting the head surface between the second row and the inner return row. The angled surface having a second edge proximate to the inner return row, the second edge protruding from the head surface a protruding distance less than a distance between the head surface and a surface to be processed. At least a portion of the plurality of second conduits intersect the head surface at an angle of between about 10 degrees and about 90 degrees and directed toward the inner return row. 
         [0021]    Still another embodiment provides a method of forming a meniscus including moving a proximity head in close proximity to a surface to be processed. The proximity head including a head surface, the head surface including a first zone, a second zone and an inner return zone. The first zone including a first flat surface region and a plurality of first discrete holes. Each one of the plurality of first discrete holes being connected to a corresponding one of a plurality of first conduits. The plurality of first discrete holes residing in the head surface and extending through the first flat surface region. At least a portion of the plurality of first discrete holes are arranged in a first row. The second zone including a second flat region and a plurality of second discrete holes. Each one of the plurality of second discrete holes being connected to a corresponding one of a plurality of second conduits. The plurality of second discrete holes residing in the head surface and extending through the second flat surface region. The inner return zone including a plurality of inner return discrete holes. The inner return zone being disposed between and adjacent to the first zone and the second zone. Each one of the plurality of the inner return discrete holes being connected to a corresponding one of a plurality of inner return conduits. The plurality of inner return discrete holes residing in the head surface and extending through the head surface. At least a portion of the plurality of inner return discrete holes are arranged in an inner return row, the first row and the inner return row being substantially parallel. The method further includes forming a dual liquid meniscus between the head surface and the surface to be processed and removing a portion of the first liquid and the second liquid through the inner return including decreasing a velocity of the first liquid proximal to the inner return to a first velocity and wherein the first velocity is less than a second velocity of the second liquid proximal to the inner return. The second velocity can also be increased proximal to the inner return. 
         [0022]    Yet another embodiment provides a method of forming a meniscus including moving a proximity head in close proximity to a surface to be processed. The proximity head including a head surface, the head surface including a first zone, a second zone and an inner return zone. The first zone including a first flat surface region and a plurality of first discrete holes. Each one of the plurality of first discrete holes being connected to a corresponding one of a plurality of first conduits. The plurality of first discrete holes residing in the head surface and extending through the first flat surface region. At least a portion of the plurality of first discrete holes are arranged in a first row. The second zone including a second flat region and a plurality of second discrete holes. Each one of the plurality of second discrete holes being connected to a corresponding one of a plurality of second conduits. The plurality of second discrete holes residing in the head surface and extending through the second flat surface region. The inner return zone including a plurality of inner return discrete holes. The inner return zone being disposed between and adjacent to the first zone and the second zone. Each one of the plurality of the inner return discrete holes being connected to a corresponding one of a plurality of inner return conduits. The plurality of inner return discrete holes residing in the head surface and extending through the head surface. At least a portion of the plurality of inner return discrete holes are arranged in an inner return row. The first row and the inner return row being substantially parallel. The method further includes forming a dual liquid meniscus between the head surface and the surface to be processed and removing a portion of the first liquid and the second liquid through the inner return including increasing a velocity of the second liquid proximal to the inner return to a second velocity and wherein the second velocity is greater than a first velocity of the first liquid proximal to the inner return. 
         [0023]    Other aspects and advantages 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 
         [0024]    The present invention will be readily understood by the following detailed description in conjunction with the accompanying drawings. 
           [0025]      FIG. 1A  illustrates a proximity head performing an operation on a surface of a substrate, in accordance with one embodiment of the present invention. 
           [0026]      FIG. 1B  is a view of the head surface of the proximity head, in accordance with an embodiment of the present invention. 
           [0027]      FIG. 1C  is a flowchart of the method operations of processing a surface, in accordance with an embodiment of the present invention. 
           [0028]      FIG. 1D  is a simplified diagram of a proximity head system, in accordance with an embodiment of the present invention. 
           [0029]      FIG. 2A  is side view of a dual input proximity head, in accordance with an embodiment of the present invention. 
           [0030]      FIG. 2B  is a bottom view of the meniscus and the head surface of the dual input proximity head, in accordance with an embodiment of the present invention. 
           [0031]      FIG. 3A  is a flowchart diagram that illustrates the method operations performed in improving the separation between the first liquid and the second liquid, in accordance with one embodiment of the present invention. 
           [0032]      FIG. 3B  is side view of a dual input proximity head, in accordance with an embodiment of the present invention. 
           [0033]      FIGS. 3C and 3D  are bottom views of the head surface of the dual input proximity head, in accordance with embodiments of the present invention 
           [0034]      FIG. 3E  is detailed view of the chamfer at the inner return conduit, in accordance with an embodiment of the present invention. 
           [0035]      FIG. 4A  is a flowchart diagram that illustrates the method operations performed in improving the separation between the first liquid and the second liquid, in accordance with one embodiment of the present invention. 
           [0036]      FIG. 4B  is side view of a dual input proximity head, in accordance with an embodiment of the present invention. 
           [0037]      FIGS. 4C and 4D  are bottom views of the head surface of the dual input proximity head, in accordance with embodiments of the present invention. 
           [0038]      FIG. 5A  is a flowchart diagram that illustrates the method operations performed in improving the separation between the first liquid and the second liquid  213 , in accordance with one embodiment of the present invention. 
           [0039]      FIG. 5B  is side view of a dual input proximity head, in accordance with an embodiment of the present invention. 
           [0040]      FIG. 5C  is a bottom view of the meniscus and the head surface of the dual input proximity head, in accordance with an embodiment of the present invention. 
           [0041]      FIGS. 5D and 5E  are side views of dual input proximity heads  570  and  580 , in accordance with embodiments of the present invention. 
           [0042]      FIG. 6A  is a dual input proximity head, in accordance with and embodiment of the present invention. 
           [0043]      FIG. 6B  is a section view of the dual input proximity head, in accordance with and embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0044]    Several exemplary embodiments for a proximity head will now be described. It will be apparent to those skilled in the art that the present invention may be practiced without some or all of the specific details set forth herein. 
         [0045]    Various embodiments of the proximity head  100  are described in more detail in co-owned U.S. patent application Ser. No. 10/330,843 filed on Dec. 24, 2002 and entitled “Meniscus, Vacuum, IPA Vapor, Drying Manifold,” and co-owned U.S. patent application Ser. No. 10/261,839 filed on Sep. 30, 2002 and entitled “Method and Apparatus for Drying Semiconductor Wafer Surfaces Using a Plurality of Inlets and Outlets Held in Close Proximity to the Wafer Surfaces.” Various embodiments and applications of proximity heads are also described in co-owned U.S. patent application Ser. No. 10/330,897, filed on Dec. 24, 2002, entitled “System for Substrate Processing with Meniscus, Vacuum, IPA vapor, Drying Manifold” and U.S. patent application Ser. No. 10/404,270, filed on Mar. 31, 2003, entitled “Vertical Proximity Processor,” and U.S. patent application Ser. No. 10/404,692 filed on Mar. 31, 2003, entitled Methods and Systems for Processing a Substrate Using a Dynamic Liquid Meniscus. The aforementioned patent applications are hereby incorporated by reference in their entirety. 
         [0046]      FIG. 1A  illustrates a proximity head  100  performing an operation on a surface  108 A of a substrate  108 , in accordance with one embodiment of the present invention. The proximity head  100  can move relative to and while in close proximity to the top surface  108 A of an item being processed  108 . The item  108  being processed can be any type of item (e.g., a metal item, a ceramic, a plastic, a semiconductor substrate, or any other desired item). It should be appreciated that the proximity head  100  may also be utilized to process (e.g., clean, dry, etch; plate, etc.) a bottom surface  108 B of the item  108 . 
         [0047]    The proximity head  100  includes one or more first conduits  112 A for delivering a first liquid  112  to a head surface  110 A of the proximity head. The proximity head  100  also includes one or more second conduits  114 A for delivering a second fluid  114  to the head surface  110 A. The second fluid  114  can be different than the first liquid  112  as will be discussed in more detail below. The proximity head  100  also includes multiple third conduits  116 A for removing the first liquid  112  and the second fluid  116  from the head surface  110 A. 
         [0048]      FIG. 1B  is a view of the head surface  110 A of the proximity head  100 , in accordance with an embodiment of the present invention. The head surface  110 A includes substantially flat regions  110 B,  110 C,  110 D. The substantially flat region  110 B includes one or more discrete holes  112 B that define the opening to one of the corresponding first conduits  112 A. Similarly, the substantially flat region  110 C includes one or more discrete holes  114 B that define the opening to one of the corresponding second conduits  114 A and the substantially flat region  110 D includes one or more discrete holes  116 B that define the opening to one of the corresponding third conduits  116 A. The discrete holes  112 B,  114 B and  116 B can be any desirable shape (e.g., substantially round, elliptical, etc.), the same or different sizes. By way of example, the discrete holes  112 B can be smaller or larger than discrete holes  114 B and  116 B. 
         [0049]    It should be understood that the proximity head  100  described in  FIGS. 1A and 1B  is a simplified exemplary proximity head. The proximity head  100  can be in many different shapes and sizes. For example, the proximity head can be round, elliptical, annular and any other desired shape. Similarly, the meniscus  102  can be any desired shape as may be defined by the arrangement of the discrete openings  112 B,  114 B and  116 B including but not limited to round, elliptical, rectangular, annular, concave, etc. Further the flat regions  110 B,  110 C and  110 D can be any shape. By way of example, the flat region  110 B can be circular, rectangular, elliptical or any other shape desired. The second flat region  110 C including the third discrete holes  116 B can fully encompass the flat region  110 B or only a portion of the flat region  110 B. Similarly, the third flat region  110 D including the second discrete holes  114 B can fully encompass the flat regions  110 B and  110 C or only a portion of the flat regions  110 B and  110 C. By way of example, the second discrete holes  114 B can be limited to only the trailing edge  104 B and/or the leading edge  104 A and/or one or more portions of the sides  104 C and  104 D, such as described in one or more of the above referenced co-pending applications which are incorporated by reference in their entirety for all purposes. The holes  112 B,  114 B,  116 B and the corresponding conduits  112 A,  114 A,  116 A can have a diameter of between about 0.004 to about 0.200 inches (i.e., 0.1 mm to about 5.0 mm). The holes  112 B,  114 B,  116 B and the corresponding conduits  112 A,  114 A,  116 A typically have a diameter of about 0.030 inches (i.e., about 0.75 mm). 
         [0050]      FIG. 1C  is a flowchart of the method operations  150  of processing a surface  108 A, in accordance with an embodiment of the present invention. In an operation  152 , the proximity head  100  is placed in close proximity to the substrate surface  108 A for processing. The close proximity H as shown in  FIG. 1A  can be from about 5 mm to less than about 0.5 mm. 
         [0051]    In an operation  154 , a liquid  112  is output from one or more first conduits  112 A and the corresponding discrete hole  112 B to form a controlled, contained, liquid meniscus  102  between the head surface  110 A and the substrate surface  108 A. The surface tension of the liquid  112  causes the liquid to be “attached” or attracted to both the head surface  110 A and the substrate surface  108 A. As a result, the outer walls  104   a ,  104 B of the meniscus  102  are formed as the surface of the liquid  112  is drawn between the head surface  110 A and the substrate surface  108 A. The liquid  112  can be any suitable liquid solution for the desired process. By way of example the liquid  112  can be water, de-ionized water (DIW), a cleaning fluid, an etching solution, a plating solution, etc. 
         [0052]    In an operation  156 , a vacuum is applied to one or more of the third conduits  116 A. The vacuum draws the liquid  112  from the meniscus  102  into the discrete holes  116 B and into the corresponding conduits  116 A. The liquid  112  drawn from the meniscus  102  can be more or less than the amount of liquid flowing into the meniscus from the first conduits  112 A. Bay way of example, there may be a greater number of third conduits  116 A than there are first conduits  112 A in the proximity head  100 . Further, as the meniscus  102  is moved across the surface  108 A, the meniscus can gather additional liquids and other contaminants from the surface. 
         [0053]    Each one of the third conduits  116 A and the corresponding discrete holes  116 B can at least partially surround the first discrete holes  112 B so that the proximity head  100  can contain the meniscus between the head surface  110 A and the substrate surface  108 A. A quantity of the first liquid  112  can flow through the meniscus to provide a very controlled processing of the substrate surface  108 A. By way of example, the first liquid  112  can be an etching chemistry for etching the substrate surface  108 A. As the etching chemistry reacts with the substrate surface  108 A, the reaction residues become entrained in the etching chemistry and the resulting contamination could reduce the concentration and etching capability of the etching chemistry. As the etching chemistry  112  is drawn away from the meniscus  102  through the third conduits  116 A, the reaction residues and other contamination are carried away from the meniscus. Simultaneously, additional non-contaminated etching chemistry is supplied to the meniscus  102  through the first conduits  112 A. 
         [0054]    In an operation  160 , the proximity head  100  can be moved relative to the substrate  108  (e.g., in direction  122 ) so as to move the meniscus  102  along the substrate surface  108 A. The side  104 A forms a leading edge of the meniscus  102  as the meniscus moves along the substrate surface  108 A in direction  122 . The meniscus  102  can remove contaminants  120  that are on the substrate surface  108 A. The contaminant  120  can be a liquid droplet, a solid residue or any other contaminants and combinations thereof (e.g., solid contaminates in a liquid solution). 
         [0055]    The side  104 B forms a trailing edge of the meniscus  102  as the meniscus moves along the substrate surface  108 A in direction  122 . The surface tension of the liquid in the meniscus  102  causes substantially all liquids on the substrate surface  108 A to be removed with the meniscus. In this manner the meniscus  102  can perform a drying operation by removing all liquid contaminants from the substrate surface  108 A. Similarly, the meniscus  102  can perform a dry-in-dry-out processing operation by applying a, for example, a wet etching or plating chemistry to the substrate surface  108 A in the meniscus and the trailing edge  104 B will remove all liquids from the etching or plating process. 
         [0056]    Moving the meniscus  102  across the substrate surface  108 A can also include moving the meniscus across the substrate surface and off the edge of the substrate surface to a second surface  124  as described in one or more of the above referenced co-pending patent applications. 
         [0057]    In an optional operation  158 , a second fluid  114  can be applied to the substrate surface  108 A. The second fluid  114  can be a surface tension controlling fluid. The surface tension controlling fluid can be one or more of isopropyl alcohol (IPA) vapor, nitrogen, organic compounds, hexanol, ethyl glycol, CO 2  gas, and other compounds miscible with water or combinations thereof. By way of example an IPA vapor can be carried by an inert carrier gas, such as nitrogen, and carried to the substrate surface  108 A. 
         [0058]    The proximity head  100  does not physically contact the substrate  108 . Only the first liquid  112  and the second fluid  114  contact the substrate  108 . 
         [0059]    The proximity head  100  can also include additional instruments or heaters or other monitors  118 . The additional instruments or heaters or other monitors  118  can be used to monitor the liquid  112  or the process being applied to the substrate surface  108 A by the meniscus  102 . By way of example the additional instruments or heaters or other monitors  118  can heat or cool the  112  and measure the surface (e.g., thickness of a layer on the surface  108  or the thickness of the substrate  108  or a depth of a surface feature) or the concentration or other chemical aspects (e.g., ph level, conductivity, etc.) of the liquid  112  or any other aspect as desired. These embodiments are described in more detail in one or more of the above referenced co-pending applications. 
         [0060]      FIG. 1D  is a simplified diagram of a proximity head system  170 , in accordance with an embodiment of the present invention. The proximity head system  170  includes a process chamber  180 , a controller  172 , a vacuum source  116 ′, a first liquid source  112 ′, a second fluid source  114 ′. The first liquid source  112 ′, the second fluid source  114 , and the vacuum source  116 ′ are coupled to the corresponding conduits  112 ,  114 ,  116  through appropriate control valves or other flow controlling mechanisms controlled by the controller  172 . 
         [0061]    The process chamber  180  can support more than one process. By way of example the process chamber  180  can support a plasma etching process and the proximity head  100  so that the plasma etching process can etch the item  108  and the proximity head can then rinse, clean and dry the item, insitu, within the single process chamber. The process chamber  180  can also be coupled to multiple other process chambers  182 ,  184 ,  186  such as are commonly referred to as a cluster tool. 
         [0062]    The proximity head system  170  can also include a second proximity head  100 ′ capable of processing a second surface  108 B of the item  108 . The proximity head system  170  can also include instruments  174  for monitoring the processes applied to the item  108 . The proximity head system  170  can also include an actuator  176  coupled to the proximity head  100  and capable of supporting and/or moving the proximity head. 
         [0063]    The controller  172  can also include a recipe  178 . The recipe  178  defines the parameters of the processing in the process chamber. The controller  172  is coupled to the processing chamber  180  and the proximity head  100  and other portions of the processing chamber as needed for controlling the processing in the process chamber. The controller  172  also includes logic  172 A for implementing the recipe  178  in the processes in the processing chamber  180 . The logic  172 A can also include the capability to monitor the results of the processes and adjust or modify one or more aspects of the recipe according to monitored results. 
         [0064]    The item  108  can be moved relative to the proximity head  100 . By way of example, the item can be a semiconductor wafer and can be rotated relative to the proximity head  100 . Similarly, the item  108  can be substantially fixed in a single location and the proximity head  100  can be moved across the surface  108 A of the item. It should also be understood that both the item  108  and the proximity head  100  can be movable. The relative motion of the proximity head  100  can be substantially, linear across the surface  108 A or can be moved in a circular or spiral fashion. The motion of the proximity head  100  can be also be specifically moved from one location to another on the surface  108 A as may be desired for a particular process being applied to the surface. 
         [0065]      FIG. 2A  is side view of a dual input proximity head  200 , in accordance with an embodiment of the present invention.  FIG. 2B  is a bottom view of the meniscus  102  and the head surface  210 A of the dual input proximity head  200 , in accordance with an embodiment of the present invention. The dual input proximity head  200  can support a meniscus  102  that is substantially divided into a first zone meniscus  102 A in the first zone  202 A and a second zone meniscus  102 B in the second zone  202 B. The first zone meniscus  102 A and the second zone meniscus  102 B are delineated by the inner return  217 B holes that connect to the inner return  217 A conduits. 
         [0066]    The first conduits  112  and the corresponding holes  112 B are separated from the inner return conduits  217 A and the corresponding inner return holes  217 B by a width W 1 . The second conduits  213 A and the corresponding holes  213 B are separated from the inner return conduits  217 A and the corresponding inner return holes  217 B by a width W 2 . Widths W 1 , W 2  may or may not be equal. Widths W 1 , W 2  can be between less than about 10 mm and greater than about 50 mm. The widths W 1 , W 2  can be between about 12 mm to about 19 mm. In one embodiment, at least one of the widths W 1 , W 2  is about 38 mm. 
         [0067]    In operation, a first liquid  112  is supplied to the meniscus  102  through the first holes  112 B. As shown by the flow arrows  212 A and  212 B, the first liquid  112  flows from the first holes  112 B, into the meniscus  102 . The first liquid  112  is removed through the first return holes  216 B and the inner return holes  217 B, respectively, when a vacuum source  116 ′ is applied to the first return conduit  216 A and the inner return conduit  217 B. 
         [0068]    Similarly, a second liquid  213  is supplied to the meniscus  102  through the second holes  213 B when a second liquid source is connected to the second conduits  213 A. As shown by the flow arrows  215 A and  215 B the second liquid  213  flows from the second holes  213 B, into the meniscus  102  and is removed through the second return holes  218 B and the inner return holes  217 B, respectively, when a vacuum source is applied to the second return conduit  218 A and the inner return conduit  217 B. 
         [0069]    The first liquid flowrate is the flowrate of the first liquid  112  through the first holes  112 B and out the first return holes  216 B and the inner return holes  217 B. The second liquid flowrate is the flowrate of the second liquid  112  through the second holes  213 B and out the second return holes  218 B and the inner return holes  217 B. The first liquid flowrate is typically approximately equal to the second liquid flowrate. 
         [0070]    The dual input proximity head  200  can be used to perform two operations such as a clean or etch and a rinse. By way of example, the first liquid  112  can be an etching chemistry and the second liquid  213  can be a rinsing liquid. As a result, as the proximity head  200  moves in direction  122 , the surface  108 A can be etched in the first zone  202 A and rinsed in the second zone  202 B and fully dried by the action of the trailing edge  104 A of the meniscus  102 . Therefore, a dry in, dry out etching and rinsing processes can be applied to the surface  108 A in a single pass of the surface by the proximity head  200 . 
         [0071]    The separation of the first zone meniscus  102 A and the second zone meniscus  102 B may not always be precise. As a result the first liquid  112  and the second liquid  213  can mix somewhat in an inner area  102 C of the meniscus  102 . The inner zone  102 C of the meniscus  102  is located near the inner return holes  217 B. The precise shape, width and concentration of the mixture in the inner zone  102 C can vary with many operational variables. By way of example, the relative flow rates of the first liquid  112  and the second liquid  213 , and/or the relative velocity (e.g., in direction  122 ) of the meniscus  102  can result in more or less of the first liquid  112  flowing into the second zone  202 B. 
         [0072]    The variation in the shape, width and concentration of the mixture in the inner zone  102 C can result in variations in the residence time of the desired concentration of the first liquid  112  in contact with the surface  108 A. By way of example, if the first liquid  112  is an etching chemistry and the first liquid flows into the second zone  202 B then the effective width D 1  of the first zone  202 A is extended, resulting in an increased residence time of the etching chemistry on the surface  108 A. The increased residence time allows the etching chemistry to etch the surface  108 A for a longer time (e.g., the time needed the first zone  102 A to move across the width D 1  in direction  122 ) and therefore the resulting etching operation is increased. Similarly, if the second liquid  213  flows into the first zone  202 A, then the residence time for the first liquid  112  is decreased and therefore the etching operation can be decreased. Ideally, the separation of the first zone meniscus  102 A and the second zone meniscus  102 B is substantially precise (e.g., widths D 1  and D 3  substantially constant) under the process variations and thereby minimize the width D 2  of the inner area  102 C of the meniscus. 
         [0073]      FIG. 3A  is a flowchart diagram that illustrates the method operations  350  performed in improving the separation between the first liquid  112  and the second liquid  213 , in accordance with one embodiment of the present invention.  FIG. 3B  is side view of a dual input proximity head  300 , in accordance with an embodiment of the present invention.  FIGS. 3C and 3D  are bottom views of the head surface  310 A of the dual input proximity head  300 , in accordance with embodiments of the present invention. 
         [0074]    In an operation  352 , a proximity head  300  is placed in close proximity to the surface  108 A to be processed. In an operation  354 , a dual liquid meniscus  102  is formed between a head surface  310 A and the surface  108 A to be processed as described above. 
         [0075]    In an operation  356 , a vacuum is applied to the inner return conduit  217 A as described above. Applying a vacuum to the inner return conduit  217 A causes a portion of the first liquid  212 B and a portion of the second liquid  215 B to flow toward the inner return holes  217 B. 
         [0076]    In an operation  358 , the portion of the first liquid  212 B flowing toward the inner return holes  217 B is slowed as the portion of the first liquid  212 B nears the inner return holes so that the velocity of the portion of the first liquid  212 B near the inner return holes is slower than the velocity of the portion of the second liquid  215 B near the inner return holes. 
         [0077]    The dual input proximity head  300  improves the separation of the first liquid  112  and the second liquid  213 . The separation of the first liquid  112  and the second liquid  213  is improved by slowing the velocity of the first liquid  212 B near the inner return holes  217 B relative to the velocity of the second liquid  215 B near the inner return holes. The slower velocity of the first liquid  212 B near the inner return holes  217 B substantially prevents the first liquid 112  flowing into the second zone  202 B. 
         [0078]    The velocity of the first liquid  112  near the inner return holes  217 B can be reduced by reducing a restriction to the flow of the first liquid near the inner return holes such as by modifying the volume of the space between the head surface  310 A and the surface  108 A near the inner return holes  217 B. As shown in  FIG. 3B , the volume of a first return zone  306  of the meniscus is increased as compared to the proximity head  200  described above. 
         [0079]    The volume of the first return zone  306  can be increased by adding chamfers  302 A, as shown in  FIG. 3C . The chamfers  302 A extend from the inner return holes  217 B toward the first holes  112 B for a distance D 4 . D 4  can be within a range of between about W 2 , as shown in  FIG. 2A  and about 1.5 mm. The chamfers  302 A can have a depth of a distance D 5 . D 5  can be within a range of about 0.1 mm to about one half H. The chamfers  320 A can have a substantially straight upper surface  302 B. Alternatively, the upper surface  302 B can include a curve to further smooth the flow of the first liquid  212 B. The upper surface  302 B forms a first angle α of between about 1 and about 89 degrees with the surface  310 A of the proximity head. By way of example the first angle α can be about 3.2 degrees, D 4  can be equal to W 2  minus about 2.0 mm and D 5  can be equal to 0.5 mm. 
         [0080]    The volume of the first return zone  306  can be increased by angling the portion of the proximity head surface  302 C in the first return zone  304 , as shown in  FIG. 3D . Similar to the chamfer  302 A, the surface portion  302 C is sloped from the surface of the proximity head  310 A toward the inner return holes  217 B. 
         [0081]      FIG. 3E  is detailed view of the chamfer  302  at the inner return conduit  217 A, in accordance with an embodiment of the present invention. The chamfer  302  can include multiple angled surfaces  362 ,  366 , multiple substantially flat surfaces  364 ,  370  and/or curved surfaces  368  and combinations thereof. The chamfer  302  shown includes a first angled surface  362  that is formed at the first angle a to the head surface  310 A. 
         [0082]    A second angled surface  366  can also be included and a substantially flat surface  364  is formed between the first angled surface  362  and the second angled surface. The second angled surface  366  can form a corresponding angle α′ with the head surface  310 A. Angles α and α′ can be equal or different. An optional substantially flat surface  370  can separate the second angled surface  366  from the inner return conduit  217 A. 
         [0083]    Alternatively, one or both of the first angled surface  362  and the second angled surface  366  can be replaced with an appropriately curved surface  368 . The curved surface  368  is formed along a curve to optimize the flow characteristics of the first liquid  112  toward the inner return conduits  217 A. 
         [0084]    By way of example the curved surface  368  can be a substantially constant radius curve across the length of the second angled surface  366 . Similarly, a single curved surface could be formed in place of both of the substantially flat surfaces  364 ,  370  and the angled surfaces  362 ,  366 . The curved surface  368  can alternatively be a non-constant radius curve such as an elliptical curve or a complex curve having multiple radii. 
         [0085]    The first angled surface  362  has a length of D 4 ′. D 4 ′ can be between 0 and D 4 . By way of example, if a single angled surface  362  is formed, as shown in  FIG. 3B  above, then D 4 ′ is equal to D 4 . 
         [0086]    The first substantially flat surface  364  length of D 4 –. D 4 ″ can be equal to 0 to about 5.0 mm as may be desired to separate the first angled surface  362  and the second angled surface  366 . 
         [0087]    The second angled surface  366  has a length of D 4 ′″. D 4 ′″ has a minimum value of 0, if the second angled surface  366  is not included. The maximum value of D 4 ′″ is determined by the desired performance characteristics. 
         [0088]    The second substantially flat surface  370  has a length of D 4 ′″. D 4 ′″ has a minimum value of 0, if the second substantially flat surface  370  is not included. The maximum value of D 4 ″″ is determined by the desired performance characteristics. D 5 ′ can be between about zero to D 5  as may be desired by the combination of substantially flat, angled and curved surfaces. It should be understood that the embodiments described in  FIGS. 3A-6B  are not drawn to scale and that the relative dimensions of the features are illustrated disproportionately to more easily describe the features. 
         [0089]      FIG. 4A  is a flowchart diagram that illustrates the method operations  450  performed in improving the separation between the first liquid  112  and the second liquid  213 , in accordance with one embodiment of the present invention.  FIG. 4B  is side view of a dual input proximity head  400 , in accordance with an embodiment of the present invention.  FIGS. 4C and 4D  are bottom views of the head surface  410 A of the dual input proximity head  400 , in accordance with embodiments of the present invention. 
         [0090]    In an operation  452 , a proximity head  400  is placed in close proximity to the surface  108 A to be processed. In an operation  454 , a dual liquid meniscus  102  is formed between a head surface  410 A and the surface  108 A to be processed as described above. 
         [0091]    In an operation  456 , a vacuum is applied to the inner return conduit  217 A as described above. Applying a vacuum to the inner return conduit  217 A causes a portion of the first liquid  212 B and a portion of the second liquid  215 B to flow toward the inner return holes  217 B. 
         [0092]    In an operation  458 , the velocity of portion of the second liquid  215 B flowing toward the inner return holes  217 B is increased as the portion of the second liquid  212 B nears the inner return holes so that the velocity of the portion of the first liquid  212 B near the inner return holes is slower than the velocity of the portion of the second liquid  215 B near the inner return holes. 
         [0093]    The dual input proximity head  400  improves the separation of the first liquid  112  and the second liquid  213 . The separation of the first liquid  112  and the second liquid  213  is improved by increasing the velocity of the second liquid  215 B near the inner return holes  217 B relative to the velocity of the first liquid  212 B near the inner return holes. The slower velocity of the first liquid  212 B near the inner return holes  217 B substantially prevents the first liquid 112  flowing into the second zone  202 B. 
         [0094]    The velocity of the second liquid  212 B can be increased by increasing a restriction to the flow of the second liquid near the inner return holes such as by modifying the volume of the space between the head surface  410 A and the surface  108 A near the inner return holes  217 B. As shown in  FIG. 4B , the volume of a second return zone  406  of the meniscus is decreased as compared to the proximity head  200  described above. 
         [0095]    The volume of the second return zone  406  can be decreased by angling a portion  402 A of the head surface  410 A, as shown in  FIGS. 4B and 4C . The angled portion  402 A extends from near the first holes  112 B toward the inner return holes  217 B for a distance D 6 . The angled portion  402 A can also include a substantially flat portion  402 A′. The substantially flat portion can extend from the inner return holes  217 B toward the second holes  213 B a distance D 6 ′. 
         [0096]    D 6  can be within a range of about W 2  as a maximum value to about 2 mm. D 6 ′ and D 6 ″ can be any desirable portions of D 6 . By way of example, D 6 ′ can be about 2.5 mm and D 6 ″ can be about 4 mm and D 6  can be equal to W 2  less D 6 ″ and D 6 ′. 
         [0097]    The angled portion  402 A can extend from the head surface  410 A a distance D 7 . D 7  can be within a range of about 0.1 mm to about H/2. By way of example, D 7  can be about 0.5 mm. 
         [0098]    The angled portion  402 A forms a second angle θ of between about 1 degree and about 89 degrees with the head surface  410 A. By way of example the second angle θ can be about 5 degrees. 
         [0099]    While the angled portion  402 A is shown with only a single angled portion and a single flat portion, it should be understood that a more complex profile including multiple flat, angled and curved surfaces, similar to those described in detail in  FIG. 3E  above, can be formed in place of the angled portion. By way of example, the angled portion  402 A can include one or more curved portions and/or one or more flat portions and one or more angled portions. 
         [0100]    The velocity of the second liquid  212 B can be increased by directing the flow of the second liquid  212 B toward the inner return holes  217 B. The flow of the second liquid  212 B can be directed toward the inner return holes  217 B by angling the second conduits  213 A and/or providing one or more angled third conduits  413 A, as shown in  FIG. 4D . The angled third conduits  413 A are formed to intersect the head surface at an angle ε. Angle ε can be between about 10 degrees and about 90 degrees. 
         [0101]      FIG. 5A  is a flowchart diagram that illustrates the method operations  550  performed in improving the separation between the first liquid  112  and the second liquid  213 , in accordance with one embodiment of the present invention.  FIG. 5B  is side view of a dual input proximity head  500 , in accordance with an embodiment of the present invention.  FIG. 5C  is a bottom view of the meniscus  102  and the head surface  510 A of the dual input proximity head  500 , in accordance with an embodiment of the present invention. 
         [0102]    In an operation  552 , a proximity head  500  is placed in close proximity to the surface  108 A to be processed. In an operation  554 , a dual liquid meniscus  102  is formed between a head surface  510 A and the surface  108 A to be processed as described above. 
         [0103]    In an operation  556 , a vacuum is applied to the inner return conduit  217 A as described above. Applying a vacuum to the inner return conduit  217 A causes a portion of the first liquid  212 B and a portion of the second liquid  215 B to flow toward the inner return holes  217 B. 
         [0104]    In an operation  558 , the portion of the first liquid  212 B flowing toward the inner return holes  217 B is slowed as the portion of the first liquid  212 B nears the inner return holes so that the velocity of the portion of the first liquid  212 B near the inner return holes is slower than the velocity of the portion of the second liquid  215 B near the inner return holes. 
         [0105]    In an operation  560 , the velocity of a portion of the second liquid  215 B flowing toward the inner return holes  217 B is increased as the portion of the second liquid  212 B nears the inner return holes so that the velocity of the portion of the first liquid  212 B near the inner return holes is slower than the velocity of the portion of the second liquid  215 B near the inner return holes. 
         [0106]    The dual input proximity head  500  improves the separation of the first liquid  112  and the second liquid  213 . The separation of the first liquid  112  and the second liquid  213  is improved by increasing the velocity of the second liquid  215 B near the inner return holes  217 B relative to the velocity of the first liquid  212 B near the inner return holes. The slower velocity of the first liquid  212 B near the inner return holes  217 B substantially prevents the first liquid 112  flowing into the second zone  202 B. 
         [0107]    The velocity of the first liquid  112  near the inner return holes  217 B is reduced by increasing the volume of the space between the head surface  310 A and the surface  108 A near the inner return holes  217 B. The volume of the first return zone  306  of the meniscus is increased as compared to the proximity head  200  described above. 
         [0108]    The velocity of the second liquid  212 B is increased by decreasing the volume in the second return zone  406 . The velocity of the second liquid  212 B is also increased by directing a portion of the second liquid  213  toward the inner return holes  217 B through the angled second conduits. The velocity of the second liquid  212 B is also increased by directing the flow of the second liquid  212 B toward the inner return holes  217 B through the angled second conduits  413 A.  FIGS. 5D and 5E  are side views of dual input proximity heads  570  and  580 , in accordance with. embodiments of the present invention. One or more curved surfaces  572 - 590  can be included in one or more of the embodiments described above. 
         [0109]      FIG. 6A  is a dual input proximity head  600 , in accordance with and embodiment of the present invention.  FIG. 6B  is a section view of the dual input proximity head  600 , in accordance with and embodiment of the present invention. The dual input proximity head  600  is similar to the dual input proximity heads  300 ,  400  and  500  described above. At least one row of the holes  112 B,  213 B,  216 B,  217 B,  218 B can be formed in a corresponding slot  612 ,  613 ,  616 ,  617 ,  618 . 
         [0110]    A source  623  of the second liquid  213  is coupled to the proximity head  600 . The source  623  supplies the second liquid  213  to the second conduits  213 A. The second conduits  213 A end in the second holes  213 B in the slot  613 . The slot  613  provides a more evenly distributed flow  613 A of the second liquid  213  from the holes  213 B before the second liquid reaches the meniscus  602  and the surface being processed  108 A. 
         [0111]    The slot  613  has a depth S 1  of about 2.5 mm to about 10 mm. The slot  613  has a width of about 0.1 mm to about 1.5 mm. 
         [0112]    It should be understood that while slot  613  is described in detail the remaining slots  612 ,  616 ,  617 ,  618  can be similarly formed. 
         [0113]    Any of the operations described herein that form part of the invention are useful machine operations. The invention also relates to a device or an apparatus for . performing these operations. The apparatus may be specially constructed for the required purposes, or it may be a general-purpose computer selectively activated or configured by a computer program stored in the computer. In particular, various general-purpose machines may be used with computer programs written in accordance with the teachings herein, or it may be more convenient to construct a more specialized apparatus to perform the required operations. 
         [0114]    The invention or portions thereof can also be embodied as computer readable code and/or logic on a computer readable medium. The computer readable medium is any data storage device that can store data which can thereafter be read by a computer system. Examples of the computer readable medium include hard drives, network attached storage (NAS), logic circuits, read-only memory, random-access memory, CD-ROMs, CD-Rs, CD-RWs, magnetic tapes, and other optical and non-optical data storage devices. The computer readable medium can also be distributed over a network coupled computer systems so that the computer readable code is stored and executed in a distributed fashion. It will be further appreciated that the instructions represented by the operations in the above figures are not required to be performed in the order illustrated, and that all the processing represented by the operations may not be necessary to practice the invention. 
         [0115]    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 may 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.