Abstract:
A method for processing a substrate using a proximity head is disclosed. The method is initiated by, providing a head with a head surface positioned proximate to a surface of the substrate. The head has a width and a length, and the head has a plurality of ports that are configured in rows along the length of the head. The plurality of rows can extend over a width of the head, and there is a first group of ports configured to dispense a first fluid. The first fluid is dispensed to the surface of the substrate forming a meniscus between the surface of the substrate and the surface of the head. The method also includes delivering gaseous carbon dioxide from a second group of ports of the head to an interface between the meniscus and the substrate. The carbon dioxide assists in promoting a reduced surface tension on the meniscus relative to surface of the substrate.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The present invention relates generally to substrate processing and equipment, and more particularly to systems that dry semiconductor substrates using a surface tension reducing gas. 
         [0003]    2. Description of the Related Art 
         [0004]    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. A slurry consists of 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. 
         [0005]    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. 
         [0006]    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. 
         [0007]    In view of the forgoing, there is a need for drying technique that minimizes the effects of droplets on the surface of the substrate. 
       SUMMARY 
       [0008]    In one embodiment, a method for processing a substrate using a proximity head is disclosed. The method is initiated by, providing a head with a head surface positioned proximate to a surface of the substrate. The head has a width and a length, and the head has a plurality of ports that are configured in rows along the length of the head. The plurality of rows can extend over a width of the head, and there is a first group of ports configured to dispense a first fluid. The first fluid is dispensed to the surface of the substrate forming a meniscus between the surface of the substrate and the surface of the head. The method also includes delivering gaseous carbon dioxide from a second group of ports of the head to an interface between the meniscus and the substrate. The carbon dioxide assists in promoting a reduced surface tension on the meniscus relative to surface of the substrate. 
         [0009]    In another embodiment, a second method for processing a substrate is disclosed. The method begins by applying a process fluid to a surface of the substrate. The process fluid forms a meniscus between a head and the surface of the substrate, the meniscus has an interface defined by the process fluid and the substrate. The method continues by applying a carbon dioxide gas flow in a directed orientation toward the interface of the meniscus. The carbon dioxide can partially mix with the meniscus at the interface so as to aid in reducing a surface tension of the meniscus over the surface of the substrate. The method continues as the meniscus is moved relative to the surface of the substrate while applying the process fluid and the carbon dioxide gas so the meniscus remains substantially intact during the movement. Wherein the application of the carbon dioxide gas is calibrated to deliver a flow that enables the moving of the meniscus at a set speed. 
         [0010]    In yet another embodiment, a proximity system for processing a substrate, is disclosed. The proximity system includes a head with a head surface configured to be positioned proximate to a surface of the substrate. The head includes a first plurality of ports configured to deliver a fluid to the surface of the substrate. When the fluid is delivered a meniscus is capable of being forming between the surface of the substrate and the head surface. The proximity system also includes a second plurality of ports being configured to deliver gaseous carbon dioxide. The gaseous carbon dioxide is delivered to an interface between the meniscus and the substrate, wherein the carbon dioxide produces a Marangoni effect on the meniscus. 
         [0011]    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 
         [0012]    The invention, together with further advantages thereof, may best be understood by reference to the following description taken in conjunction with the accompanying drawings. 
           [0013]      FIG. 1  is a high level schematic of a process module, in accordance with one embodiment of the present invention. 
           [0014]      FIG. 2  illustrates an exemplary configuration of a proximity station, in accordance with one embodiment of the present invention. 
           [0015]      FIG. 3A  illustrates an exemplary side view of the proximity station as the substrate enters the meniscus in accordance with one embodiment of the present invention. 
           [0016]      FIG. 3B  and  FIG. 3C  illustrate exemplary schematics of port layouts on the surface of the head in accordance with one embodiment of the present invention. 
           [0017]      FIG. 3D  illustrates an exemplary side view of the proximity station as the substrate passes through the meniscus, in accordance with one embodiment of the present invention. 
           [0018]      FIG. 4  illustrates a Marangoni effect between the gas dispensed from port and the meniscus, in accordance with one embodiment of the present invention. 
           [0019]      FIG. 5  illustrates an exemplary condition where micro-droplets are formed on the surface of the substrate, in accordance with one embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0020]    An invention is disclosed for processing a substrate and more specifically, for producing a Marangoni effect using a gas, such as carbon dioxide. In embodiments of the present invention, a meniscus is applied to a surface of a substrate with a proximity head. A proximity head is an apparatus that can receive fluids, and remove fluids from a surface of a substrate, when the proximity head is placed in close relation to the surface of the substrate. In one example, the proximity head has a head surface and the head surface is placed substantially parallel to the surface of the substrate. The meniscus is thus defined between the head surface and the surface of the substrate. Different degrees of proximity are possible, and example proximity distances may be between about 0.2 mm and about 4 mm, and in another embodiment between about 0.3 mm and about 1.5 mm. 
         [0021]    The proximity head, in one embodiment, will receive a plurality of fluid inputs and is also configured with vacuum ports for removing the fluids that were provided. A “meniscus”, as used herein, is a controlled fluid meniscus that forms between the surface of a proximity head and a substrate surface, and surface tension of the fluid holds the meniscus in place and in a controlled form. Controlling the meniscus is also ensured by the controlled delivery and removal of fluid, which enables the controlled definition of the meniscus, as defined by the fluid. The meniscus may be used to either clean, process, etch, or process the surface of the substrate. The processing on the surface may be such that particulates or unwanted materials are removed by the meniscus. In a related embodiment, the meniscus may be formed out of a tri-state body (e.g., a foamed solution), and the solution may simply sit on the surface at the substrate, but mechanically function different than fluid solutions that are affected by surface tension. A foamed solution behaves more like a non-Newtonian fluid. 
         [0022]    A “substrate,” as an example used herein, denotes without limitation, semiconductor wafers, hard drive disks, optical discs, glass substrates, and flat panel display surfaces, liquid crystal display surfaces, etc., which may become contaminated during manufacturing or handling operations. Depending on the actual substrate, a surface may become contaminated in different ways, and the acceptable level of contamination is defined in the particular industry in which the substrate is handled. 
         [0023]    In one embodiment, the fluid delivery to the proximity head is dynamically configurable, such that dispensing and removing of process fluids (or mixtures) can be preconfigured, depending on the desired application. A programmable distribution manifold can partly assist the configuration of a proximity head. The programmable distribution manifold can define which fluids are delivered to the proximity head and can also define where on the proximity head the fluids will be delivered. The result is that the fluids can be placed on just the desired regions of the substrate, and in desired orders. For instance, different fluid can be delivered to different parts of the proximity head, so that fluids of different types can perform different processes, one after another, as the head or substrate moves. 
         [0024]    In one example, multiple menisci can be generated, of different sizes and placement, as configured by the programmable distribution manifold. The proximity head is also provided with a plurality of ports, so that the controlled delivery and selection of regions of the proximity is facilitated, once the fluids are directed to the proximity head from the programmable distribution manifold. 
         [0025]    In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention. It will be apparent, 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 steps have not been described in detail in order not to unnecessarily obscure the present invention. 
         [0026]      FIG. 1  is a high level schematic of a process module  104 , in accordance with one embodiment of the present invention. The process module may be located in a clean room  102  and connected to a computer  106 . The clean room  102  can include facilities  110  that are capable of providing fluids and gases for use within the process module  104 . To control storage and application of the fluids and gases, the process module  104  can include fluid controls  111  and gas controls  108 . The gas controls  108  can include air filters, gas valves, and devices to control the temperature and humidity of gases used in the process module. 
         [0027]    In one embodiment, the fluid controls  111  can include fluid handlers  112 , flow controllers  114 , and valves  116 . The fluid handlers  112  can be used to store process chemicals, de-ionized water, and other materials or solutions. The flow controllers  114  and valves  116  can be used to control the mixing and dispensing of fluids. Additional fluid controls  111  can include equipment that can recycle process chemicals and de-ionized water. 
         [0028]    The process module  104  can have a single process station or multiple process stations. It should be clear that the process module  104  may contain fewer or more process stations than shown in  FIG. 1 . An individual process station can perform one, or a combination of processes including, but not limited to, plating, etching, rinsing, cleaning or other operations typically used in the semiconductor processing environment. 
         [0029]    In one embodiment proximity stations  118  and  122  can contain a proximity head comprised of a head  150   a  and a head  150   b.  A meniscus  154  can be formed from a process fluid between the head  150   a  and the head  150   b  and a substrate  152 , held by carrier  156 , can pass through the meniscus  154 . Another example of a proximity station is proximity station  120 . Proximity station  120  can include carrier  156  and a head  150   a  that can produce a meniscus  154 . A brush  158  for cleaning a surface of the substrate  152  can also be included in proximity station  120 . The proximity stations shown in  FIG. 1  are for exemplary purpose and should not be considered limiting in functionality nor considered to scale of actual proximity stations. 
         [0030]      FIG. 2  illustrates an exemplary configuration of a proximity station  118 , in accordance with one embodiment of the present invention. The substrate  152  is inserted into the proximity station  118  that can include a proximity head having a head  150   a  and a head  150   b.  A carrier  156  may hold and guide the substrate  152  between the head  150   a  and the head  150   b.  In one embodiment, the meniscus  154  is initially formed between the head  150   a  and the head  150   b  In another embodiment, a meniscus  154  is allowed to form between a surface of the head  150   a  and a surface of the substrate  152  (and surfaces of the carrier  156 ). The meniscus  154  is a controlled fluid meniscus that can form between the surface of a proximity head  150   a  and the substrate surface, and surface tension of the fluid holds the meniscus  154  in place and in a controlled form. Controlling delivery and removal of a meniscus fluid may also ensure further control of the meniscus  154 . The meniscus  154  may be used to clean, process, etch, or process the surface of the substrate  152 . 
         [0031]    The meniscus  154  is constrained within the proximity station by supplying the meniscus fluid to the head  150   a  and the head  150   b  by removing the meniscus fluid with a vacuum in a controlled manner. Optionally, a gas tension reducer may be provided to the proximity heads  150   a,  so as to reduce the surface tension between the meniscus  154  and the substrate  152 . The gas tension reducer supplied to the proximity heads  150   a  and  150   b  allows the meniscus  154  to move over the surface of the substrate  152  at an increased speed (thus increasing throughput). Examples of a gas tension reducer may be isopropyl alcohol mixed with nitrogen (IPA/N 2 ). Another example of a gas tension reducer may be carbon dioxide (CO 2 ). Other types of gasses may also be used so long as the gasses do not interfere with the processing desired for the particular surface of the substrate  152 . 
         [0032]    The embodiment shown in  FIG. 2  is shown connected to a single fluid supply. It should be understood that other embodiments of a proximity head can include multiple fluid supplies and multiple varieties of gas for tension reduction. Such an embodiment may enable a single proximity head to apply and remove multiple process fluids. Further, for completeness, it should be understood that the proximity station can be in any orientation, and as such, the meniscus  154  can be applied to surfaces that are not horizontal (e.g., vertical substrates or substrates that are held at an angle). 
         [0033]      FIG. 3A  illustrates an exemplary side view of the proximity station  118  as the substrate  152  enters the meniscus  154  in accordance with one embodiment of the present invention. The meniscus  154  can be initially established between head  150   a  and  150   b  by supplying a fluid using meniscus supply port  304   a  and meniscus supply port  304   b.  The formation of the meniscus  154  creates meniscus/head boundaries  310  where a boundary  306  of the meniscus  154  is in contact with a surface  308   a  of the head  150   a  or a surface  308   b  of the head  150   b.  As the carrier  156  moves the substrate  152  between the head  150   a  and head  150   b,  the substrate  152  encounters vacuum ports  300   a / 300   a′  and  300   b / 300   b′ . In one embodiment, the vacuum ports  300   a / 300   a′  and  300   b / 300   b′  are configured to remove fluids from the meniscus  154 , but also assist in removing any contaminants, particles or unwanted material from the surface of the substrate  152 . By carefully controlling a vacuum rate of the vacuum ports  300   a / 300   a′  and  300   b / 300   b′ , it is possible to ensure that the meniscus  154  is held between the surface  308   a  of the head  150   a  and the surface  308   b  of the head  150   b.    
         [0034]    After passing under the vacuum ports  300   a  and  300   b,  the carrier  156  and the substrate  152  enter the meniscus  154 . As the carrier  156  and the substrate  152  enter the meniscus  154 , meniscus/surface boundaries  312  are formed at an interface between the boundary  306  of the meniscus  154  and a surface  152   a  or a surface  152   b  of the substrate  152 . By using the vacuum techniques described above, and by controlling the input of meniscus fluid through the meniscus supply ports  304   a  and  304   b,  the meniscus  154  can remain stable as meniscus fluid is displaced by the carrier  156  and the substrate  152 . 
         [0035]    As shown in  FIG. 3A , gas ports  302   a  and  302   b,  capable of dispensing the gas tension reducer, are positioned to the left of vacuum port  300   a′  and  300   b′  respectively. As previously discussed, the gas tension reducer can reduce the surface tension between the meniscus  154  and the substrate  152 . The gas can also be used in conjunction with the vacuum ports  300   a′  and  300   b′  to assist in containing the meniscus  154  within the heads  150   a  and  150   b.  Additional benefits and effects of the gas on the boundary  306  will be discussed in  FIG. 3D . In other embodiments, additional gas ports may be positioned to the right of vacuum ports  300   a  and  300   b  as shown in  FIG. 3D . Note, the gas ports  300   a′ / 300   a  and  302   a′ / 302   a,  as illustrated in  FIG. 3A  and  FIG. 3D , are shown angled toward the meniscus  154 . The angle shown is exemplary and should not be considered limiting as angles of the gas ports can vary depending on a particular application. 
         [0036]      FIG. 3B  and  FIG. 3C  illustrate exemplary schematics of port layouts on the surface  308   a  of the head  150   a  in accordance with one embodiment of the present invention.  FIG. 3B  illustrates the bottom view of head  150   a  from  FIG. 3A  where vacuum ports  300   a  are followed by meniscus supply ports  304   a.  Following the meniscus supply ports  304   a  are vacuum ports  300   a′  and gas ports  302   a.    FIG. 3C  illustrates an embodiment of a head  150   a  where gas ports  302   a′ / 302   a  surround the vacuum ports  300   a / 300   a′ . Also illustrated in  FIG. 3C  are the vacuum ports  300   a / 300   a′  surrounding the meniscus supply ports  304   a.  Note, in  FIG. 3B  and  FIG. 3C , openings to the vacuum ports  300   a / 300   a′  and meniscus supply ports  304   a  are shown as squares and triangles respectively. The various shapes of port openings were made in an effort to help differentiate the types of ports within the figures. It should be understood that port openings can be made in a variety of shapes, and what is shown in  FIG. 3B  and  FIG. 3C , should not be considered limiting. 
         [0037]      FIG. 3D  illustrates an exemplary side view of the proximity station  118  as the substrate  152  passes through the meniscus  154 , in accordance with one embodiment of the present invention. As the carrier  156  and the substrate  152  exit the meniscus  154 , ports  302   a  and  302   b  are used to dispense a flow of gas tension reducer to the meniscus/surface boundary  312 . In one embodiment, the gas tension reducer can be gaseous CO 2  that can be supplied to the ports  302   a  and  302   b  under pressure, or simply delivered to ports  302   a  and  302   b  so that CO 2  flows out and is present near the boundary  306 . If pressurized, the CO 2  flow may be delivered at a pressure of between about 5 psi and about 60 psi. In one example, the CO 2  can be diluted with inert gases or can be applied as pure CO 2 . In one embodiment, the flow of CO 2  is at least equivalent to the flow of other tension reducing gases, such as an IPA/N 2  mixture, and in other embodiments, the flow of CO 2  can be more. In still another example, the flow of CO 2  from each of ports  302   a  and ports  302   b  is in a range between about 1.1 to about 1.8 times the a flow that may be provided when anIPA/N 2  mixture is used. When an IPA/N 2  mixture is used, the flow is calibrated for the specific application, the type of fluids being applied, the speed of the substrate relative to the meniscus  154 , and other factors. In a more general sense, the flow of CO 2  should be configured to increase if the relative speed of the meniscus moving over the substrate is desired to be increased (e.g., to increase throughput, etc.). 
         [0038]    The gas tension reducer, in one embodiment CO 2 , is provided to promote a type of Marangoni effect on the fluids of the meniscus  154 . A Marangoni effect is the mass transfer on, or in, a liquid layer due to difference in surface tension. Since a liquid with a high surface tension pulls more strongly on the surrounding liquid than one with a low surface tension, the presence of a gradient in surface tension will cause the liquid to flow away from regions of low surface tension. In the defined embodiments, dispensing of CO 2  gas assists in reducing the surface tension at the meniscus/surface boundary  312  at the surface  152   a  of the substrate  152 . By lowering the surface tension of the meniscus/surface boundary  312  relative to the surface of the substrate  152 , it is possible to move or traverse the meniscus  154  along the surface of the substrate  156  at faster rates, and minimizing (or eliminate) traces of the fluids, droplets or staining from dried fluid droplets or beads. 
         [0039]    In one embodiment, the heads  150   a  and  150   b  remain stationary while the carrier  156  and the substrate  154  move through the meniscus  154  at a speed between about 10 mm/second and about 40 mm/second. In another embodiment, the heads  150   a  and  150   b  and the meniscus  154  can move while the carrier  156  and the substrate  152  remain stationary. In yet another embodiment, heads  150   a  and  150   b  and the substrate  152  can be moving with a relative speed of the substrate  152  to the heads  150   a  and  150   b  being a speed between about 10 mm/second and about 40 mm/second. 
         [0040]    Using CO2 to produce the Marangoni effect provides additional benefits including, but not limited to, reduced flammability compared to other gases or gas mixtures that can produce the Marangoni effect. The inert nature of CO 2  can reduce flammability of the gas dispensed by gas ports  302   a / 302   a′  and  302   b / 302   b′ . The reduction in flammability can allow for a reduction in fire suppression equipment, thereby simplifying and reducing costs associated with designing, building and maintaining proximity stations. Additional simplification and cost reduction can be realized by using CO 2  because gaseous CO 2  is readily available and may not require processing, such as vaporization and saturation, before being supplied to the heads  150   a  and  150   b.    
         [0041]    Additionally, after exposure to CO 2 , there may be very little change to the meniscus fluid, thus simplifying recycling of the meniscus fluid when compared to the recycling of meniscus fluids that are exposed to other various gases. Gases other than CO 2  can include vaporized additives. After the meniscus fluid is repeatedly exposed to the gases, the vaporized additives can condense within the meniscus fluid and eventually alter the properties of the meniscus fluid. Failure to remove the condensed additives can result in undesirable processing characteristics including, but not limited to, decreased efficacy of the meniscus fluid. As the condensed additives may be thoroughly mixed and integrated into the meniscus fluid, additional equipment and process steps necessary to remove the condensed additive complicating recycling of the meniscus fluid. Using CO 2 , changes to the meniscus fluid can be minimized and controlled by careful selection of the meniscus fluid. Additionally, because CO2 does not introduce an additive to the meniscus fluid that must be removed, costs associated with designing, implementing and operating recycling equipment can be reduced. 
         [0042]      FIG. 4  illustrates a Marangoni effect between the gas dispensed from port  302   a  and the meniscus  154 , in accordance with one embodiment of the present invention. For simplicity, the meniscus/surface boundary  312  between the meniscus  154  and the surface  152  of the substrate  152  is shown. A surface tension gradient  400  along the surface of the meniscus, created by the gas dispensed from the port  302   a,  is shown from the meniscus/surface boundary  312  to the boundary  306 . The gas from port  302   a,  along with the meniscus fluid delivered from the meniscus supply port, mix in such a manner that the gas and the meniscus fluid mixture decreases the tension at the boundary  312  creating a relatively higher surface tension at the boundary  306 . Higher tension along the boundary  306  relative to the meniscus/surface boundary  312  produces the Marangoni effect where fluid with a lower surface tension is pulled toward fluid with a higher surface tension. The result is fluid from the meniscus/surface boundary  312  being drawn toward the bulk of the meniscus  154  resulting in the substrate  152  being substantially dry after passing under gas port  302   a.    
         [0043]      FIG. 5  illustrates an exemplary condition where micro-droplets  500  are formed on the surface  152   a  of the substrate  152 , in accordance with one embodiment of the present invention. After the substrate  152  passes under gas port  302   a  it is possible for micro-droplets  500  of meniscus fluid to remain on the surface of the substrate  152 . While generally undesirable, the micro-droplets  500  can be formed when the meniscus/surface boundary  312  breaks leaving a micro-droplet  500  of meniscus fluid on the surface  152   a  of the substrate  152 . It should be understood that micro-droplets  500  can be extremely small and can evaporate almost instantaneously after breaking away from the meniscus  154 . Micro-droplets  500  are undesirable because the micro-droplets  500  can contain a minute amount of potential contaminant material. After evaporation of the micro-droplet  500 , the contaminant material can be deposited on the surface  152   a  of the substrate  152 . 
         [0044]    In one embodiment, dispensing of CO 2  from port  302   a  can alter the pH of the fluid of the meniscus  154  and result in a decreased amount of a contaminant such as silicic acid in the micro-droplets  500 . As the substrate  152  passes under the port  302   a,  the meniscus fluid at the meniscus/surface boundary  312  is exposed to, and can become saturated with, CO 2 . In one embodiment, saturating the meniscus fluid at the meniscus/fluid boundary  312  can lower the pH of the meniscus fluid. The lowered pH at the meniscus/fluid boundary  312 , can result in a reduction in the formation of silicic acid (H 2 SiO 3 ). Thus, if a micro-droplet  500  is formed and evaporates, the reduction in silicic acid caused by exposure to CO2 can result in a reduction of trace contaminant material on the surface  152   a  of the substrate  152 . 
         [0045]    In other embodiments, to achieve a desired change in the meniscus fluid after exposure to the gas tension reducer, an additive sensitive to the gas tension reducer may be added to the meniscus fluid. In an embodiment that uses CO 2  as the gas tension reducer and the desired change is a reduction in the formation of silicic acid, a surfactant can be added to the meniscus fluid. Examples of surfactants that are CO 2  sensitive and can reduce in formation of silicic acid include, but are not limited to, amide oxides such as: dodecyldimethylamine oxide (DDMAO), trimethylamine oxide (TMAO), N,N-dimethyl-N-dodecyl amine oxide, N,N-dimethyl-N-tetradecyl amine oxide, N,N-dimethyl-N-hexadecyl amine oxide, N,N-dimethyl-N-octadecyl amine oxide, N,N-dimethyl-N-(Z-9-octadecenyl)-N-amine oxide, N-dodecyl-N,N-dimethyl glycine, phosphates, phosphites, phosphonates, lecithins, phosphate esters, phospatidylethanolamines, phosphatidylcholines, phosphatidyl serines, phosphatidylinositols, and B′-O-lysylphosphatidylglycerols. 
         [0046]    While the change in pH caused by exposure to CO 2  may be limited to the boundary  306  of the meniscus  154 , repeated exposure may eventually adversely affect the meniscus fluid. However, it is still possible to recycle the meniscus fluid by using recycling equipment capable of monitoring and adjusting the pH of the recycled meniscus fluid. 
         [0047]    The dispensing of CO 2 , and operation of the proximity head may be controlled in an automated way using computer control. Thus, aspects of the invention may be practiced with other computer system configurations including hand-held devices, microprocessor systems, microprocessor-based or programmable consumer electronics, minicomputers, mainframe computers and the like. The invention may also be practiced in distributing computing environments where tasks are performed by remote processing devices that are linked through a network. 
         [0048]    With the above embodiments in mind, it should be understood that the invention may employ various computer-implemented operations involving data stored in computer systems. These operations are those requiring physical manipulation of physical quantities. Usually, though not necessarily, these quantities take the form of electrical or magnetic signals capable of being stored, transferred, combined, compared, and otherwise manipulated. Further, the manipulations performed are often referred to in terms, such as producing, identifying, determining, or comparing. 
         [0049]    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, such as the carrier network discussed above, 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. 
         [0050]    The invention can also be embodied as computer readable code 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), read-only memory, random-access memory, CD-ROMS, CD-Rs, CD-RWS, DVDS, Flash, 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. 
         [0051]    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. 
         [0052]    For more information on the formation of a meniscus and the application to the meniscus to a surface of a substrate, reference may be made to: (1) U.S. Pat. No. 6,616,772, issued on Sep. 9, 2003 and entitled “M ETHODS FOR WAFER PROXIMITY CLEANING AND DRYING ”; (2) U.S. patent application Ser. No. 10/330,843, filed on Dec. 24, 2002 and entitled “M ENISCUS, VACUUM , IPA  VAPOR, DRYING MANIFOLD ”; (3) U.S. Pat. No. 6,998,327, issued on Jan. 24, 2005 and entitled “M ETHODS AND SYSTEMS FOR PROCESSING A SUBSTRATE USING A DYNAMIC LIQUID ”; (4) U.S. Pat. No. 6,998,326, issued on Jan. 24, 2005 and entitled “P HOBIC BARRIER MENISCUS SEPARATION AND CONTAINMENT ”; (5) U.S. Pat. No. 6,488,040, issued on Dec. 3, 2002 and entitled “C APILLARY PROXIMITY HEADS FOR SINGLE WAFER CLEANING AND DRYING ”; (6) U.S. patent application Ser. No. 10/261,839, filed on Sep. 30, 2002 and entitled “M ETHOD AND APPARATUS FOR DRYING SEMICONDUCTOR WAFER SURFACES USING A PLURALITY OF INLETS AND OUTLETS HELD IN CLOSE PROXIMITY TO THE WAFER ”; and (7) U.S. patent application Ser. No. 10/957,092, filed on Sep. 30, 2004 and entitled “S YSTEM AND METHOD FOR MODULATING FLOW THROUGH MULTIPLE PORTS IN A PROXIMITY HEAD ”; each is assigned to Lam Research Corporation, the assignee of the subject application, and each is incorporated herein by reference. 
         [0053]    Although proximity heads were defined for the purpose of fluid delivery, the fluid may be of different types. For instance, the fluids may be for plating metallic materials. Example systems and processes for performing plating operations are described in more detail in: (1) U.S. Pat. No. 6,864,181, issued on Mar. 8, 2005; (2) U.S. patent application Ser. No. 11/014,527 filed on Dec. 15, 2004 and entitled “W AFER SUPPORT APPARATUS FOR ELECTROPLATING PROCESS AND METHOD FOR USING THE SAME ”; (3) U.S. patent application Ser. No. 10/879,263, filed on Jun. 28, 2004 and entitled “M ETHOD AND APPARATUS FOR PLATING SEMICONDUCTOR WAFERS ”; (4) U.S. patent application Ser. No. 10/879,396, filed on Jun. 28, 2004 and entitled “E LECTROPLATING HEAD AND METHOD FOR OPERATING THE SAME ”; (5) U.S. patent application Ser. No. 10/882,712, filed on Jun. 30, 2004 and entitled “A PPARATUS AND METHOD FOR PLATING SEMICONDUCTOR WAFERS ”; (6) U.S. patent application Ser. No. 11/205,532, filed on Aug. 16, 2005, and entitled “R EDUCING MECHANICAL RESONANCE AND IMPROVED DISTRIBUTION OF FLUIDS IN SMALL VOLUME PROCESSING OF SEMICONDUCTOR MATERIALS ”; and (7) U.S. patent application Ser. No. 11/398,254, filed on Apr. 4, 2006, and entitled “M ETHODS AND APPARATUS FOR FABRICATING CONDUCTIVE FEATURES ON GLASS SUBSTRATES USED IN LIQUID CRYSTAL DISPLAYS ”; each of which is herein incorporated by reference. 
         [0054]    Other types of fluids may be non-Newtonian fluids. For additional information regarding the functionality and constituents of Newtonian and on-Newtonian fluids, reference can be made to: (1) U.S. application Ser. No. 11/174,080, filed on Jun. 30, 2005 and entitled “M ETHOD FOR REMOVING MATERIAL FROM SEMICONDUCTOR WAFER AND APPARATUS FOR PERFORMING THE SAME ”; (2) U.S. patent application Ser. No. 11/153,957, filed on Jun. 15, 2005, and entitled “M ETHOD AND APPARATUS FOR CLEANING A SUBSTRATE USING NON -N EWTONIAN FLUIDS ”; and (3) U.S. patent application Ser. No. 11/154,129, filed on Jun. 15, 2005, and entitled “M ETHOD AND APPARATUS FOR TRANSPORTING A SUBSTRATE USING NON-NEWTONIAN FLUID ”; each of which is incorporated herein by reference. 
         [0055]    Another material may be a tri-state body fluid. A tri-state body is one which includes one part gas, one part solid, and one part fluid. For additional information about the tri-state compound, reference can be made to Patent Application No. 60/755,377, filed on Dec. 30, 2005 and entitled “M ETHODS, COMPOSITIONS OF MATTER, AND SYSTEMS FOR PREPARING SUBSTRATE SURFACES ”. This Patent Application was incorporated herein by reference. 
         [0056]    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.