Abstract:
An apparatus and method for drawing a sample of a chemical-mechanical polishing slurry for analysis of at least one property, e.g., particle size distribution, is described. The apparatus comprises (i) a plurality of sample delivery lines, each line carrying a chemical-mechanical polishing slurry, (ii) a manifold in fluid communication with the plurality of sample delivery lines, (iii) means for opening and closing the fluid communication between each sample delivery line and the manifold, (iv) an aspirator in fluid communication with the manifold, (vi) means opening and closing the fluid communication between the aspirator and the manifold, (vii) a pressure between the aspirator and the sample delivery lines, a reduction in the pressure resulting in the draw of a sample from the sample delivery line into the manifold when the fluid communication between the line and the manifold is open, (viii) a sensor for measuring the at least one property of the slurry, the sensor in fluid communication with the manifold, and (ix) means for opening and closing the fluid communication between the manifold and the sensor.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]    Priority is claimed to U.S. provisional patent application Serial No. 60/313,442 filed on Aug. 17, 2001. 
     
    
     
       BACKGROUND OF THE INVENTION  
         [0002]    1. Field of the Invention  
           [0003]    The invention relates to sampling chemical-mechanical polishing slurries. In one aspect, the invention relates to sampling such slurries to monitor one or more properties of the slurry while in another aspect, the invention relates to using an aspirator to draw the slurry into a liquid sampling system.  
           [0004]    2. Description of the Related Art.  
           [0005]    A chemical-mechanical polishing (CMP) system is often employed in the microelectronics industry to contour and/or polish semiconductor wafers. These systems typically contain and employ a “slurry” which is cycled throughout the system such that the slurry contacts and/or impinges upon the wafers. As the cycling slurry impacts and/or passes over the wafers, the wafers are contoured and polished.  
           [0006]    In order to maintain the consistency, performance, efficiency, and/or usefulness of the system, the “health” of the slurry must be maintained. Slurry instability, external contamination, or process conditions (e.g., shear-inducing pressure gradients, flow rates, and exposure to air) may all compromise slurry health. Thus, slurry properties (e.g., specific gravity, pH, weight percent solids, ionic contamination level, zeta potential, and particle size distribution (PSD)), are often closely monitored by sampling systems.  
           [0007]    Of all the slurry health properties, perhaps the most important and frequently monitored is PSD. In the industry, PSD can be observed using a variety of instruments such as sensors, analyzers, and like devices (collectively referred to as sensors) that are commercially available from a host of manufacturers. For example, one such sensor is the AccuSizer 780/OL (AccuSizer) manufactured by Particle Sizing Systems (PSS) of Santa Barbara, Calif.  
           [0008]    Unfortunately, while these PSD sensors are generally suitable for analyzing slurry, these sensors can possess disadvantages in some circumstances. Certain of these sensors are generally limited to sampling a single slurry at a single sampling point (i.e., a location within a CMP system from where a sample is taken). In other words, each CMP system, as well as each slurry used within that CMP system, would require a dedicated sensor. Since integrated circuit manufacturers, as well as others, often desire to analyze numerous different slurries, from multiple sampling points (i.e., locations), a one-to-one ratio of sensor to slurry would dramatically increases costs. Therefore, a liquid sampling system, using a single sensor, capable of monitoring one of a plurality of slurries from multiple sampling points was developed.  
           [0009]    The liquid sampling system was built around a sensor to permit measurement of a number of different slurries, from multiple sample points, by utilizing a multi-port valve manifold. The multi-port valve manifold is operable, within the liquid sampling system, to selectively route any one of a number of different slurries, from a variety of locations, to a single sensor for PSD analysis.  
           [0010]    While developing, testing and using the liquid sampling system, the need to repeatedly draw and/or introduce the slurry into the liquid sampling system became apparent. The slurries could, and often were, provided by one of many independent slurry supply lines. Therefore, in order to draw slurry into the liquid sampling system, a pump or like device would need to be associated with every slurry supply line. In other words, a one-to-one ratio of slurry supply lines to pumps would be required.  
           [0011]    Unfortunately, the use of multiple pumps within the liquid sampling system presented numerous drawbacks and disadvantages. Specifically, the cost of purchasing, maintaining, and operating numerous pumps posed a significant financial burden. The pumps can be expensive, can be subject to mechanical difficulties that lead to down-time, and can voraciously consume energy. Further, the pumps can occupy valuable space within the liquid sampling system and, therefore, render the liquid sampling system cumbersome. Thus, an apparatus and method capable of drawing a liquid into a liquid sampling system without the use of multiple pumps or other multiple drawing apparatus are desirable.  
         SUMMARY OF THE INVENTION  
         [0012]    In one aspect, the invention is a method of drawing a liquid sample into a liquid sampling system from at least one of a plurality of liquid delivery lines, the liquid sampling system comprising (i) a multi-valve manifold in fluid communication with the liquid delivery lines, (ii) an aspirator in fluid communication with the manifold, and (iii) a pressure between the aspirator and the liquid delivery lines, the method comprising:  
           [0013]    activating the aspirator to reduce the pressure in the manifold relative to the liquid delivery lines; and  
           [0014]    activating at least one valve on the manifold to selectively draw into the manifold a liquid sample from at least one liquid delivery line.  
           [0015]    The aspirator is activated by passing a fluid, e.g., water, through it, and the liquid sample is typically a chemical-mechanical polishing slurry.  
           [0016]    In another embodiment, the invention is an apparatus for drawing a sample of a chemical-mechanical polishing slurry for analysis of at least one property, the apparatus comprising (i) a plurality of sample delivery lines, each line carrying a chemical-mechanical polishing slurry, (ii) a manifold in fluid communication with the plurality of sample delivery lines, (iii) means for opening and closing the fluid communication between each sample delivery line and the manifold, (iv) an aspirator in fluid communication with the manifold, (vi) means opening and closing the fluid communication between the aspirator and the manifold, (vii) a pressure between the aspirator and the sample delivery lines, a reduction in the pressure resulting in the draw of a sample from the sample delivery line into the manifold when the fluid communication between the line and the manifold is open, (viii) a sensor for measuring the at least one property of the slurry, the sensor in fluid communication with the manifold, and (ix) means for opening and closing the fluid communication between the manifold and the sensor.  
           [0017]    The means for opening and closing the fluid communication between the manifold and the sample delivery lines, aspirator and sensor is typically at least one valve. The sensor can vary to convenience, e.g., an optical particle counter.  
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0018]    Embodiments of the invention are disclosed with reference to the accompanying drawings and are for illustrative purposes only. The invention is not limited in its application to the details of construction, or the arrangement of the components, illustrated in the drawings. The invention is capable of other embodiments or of being practiced or carried out in other various ways. Like reference numerals are used to indicate like components.  
         [0019]    [0019]FIG. 1 is a schematic representation of a liquid sampling system comprising one embodiment of an aspirator in accordance with one aspect of the present invention.  
         [0020]    [0020]FIG. 2 is a perspective view of a valve manifold employed within the liquid sampling system of FIG. 1.  
         [0021]    [0021]FIG. 3 is a more detailed schematic representation of the aspirator of FIG. 1.  
         [0022]    [0022]FIG. 4 is a flowchart outlining the steps for drawing a fluid into the fluid sampling system with the aspirator of FIGS. 1 and 3. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0023]    Various items of equipment, such as fittings, valves, mountings, pipes, sensors, monitoring equipment, wiring, and the like have been omitted to simplify the description. However, such conventional equipment and its uses are known to those skilled in the art and can be employed as desired. Moreover, although the invention is described below in the context of slurries used in chemical-mechanical polishing processes, those skilled in the art will recognize that the invention can be employed with, and has applicability to, many other and different processes.  
         [0024]    Referring to FIG. 1, a schematic representation of a liquid sampling system  10  is illustrated. In preferred embodiments, system  10  comprises a liquid sampling system known as the intelligent Slurry Particle Equipment (iSPEQ) system. The iSPEQ system is operable to monitor the health of chemical-mechanical polishing slurries. An exemplary description of the iSPEQ system is provided in commonly-owned, co-pending U.S. patent application Ser. No. __/___,___ filed Aug. 9, 2002, entitled “Sampling and Measurement System with Multiple Slurry Chemical Manifold”, and the contents and disclosure of that application are incorporated into the present application by this reference as if fully set forth herein.  
         [0025]    System  10  comprises sensor  12 , multi-port valve manifold  14 , bottle sample station  16 , system drain  18 , and aspirator  60 . System  10  is operable to monitor and/or analyze a collected sample of slurry (or other liquid), that has been selectively and/or sequentially provided to the system. One example of slurry suitable for testing in system  10 , and commonly used in CMP systems, is Semi-Sperse SS-12 manufactured by Cabot Corporation, Boston, Mass. When operating system  10  slurry can be obtained from any number of sampling points (e.g., locations) within a single CMP system (not shown) and/or within several CMP systems. Also, slurry can be taken at any time during the “life” (i.e., period of use in a CMP system and/or systems) of the slurry.  
         [0026]    For system  10  to monitor and/or analyze a slurry sample, the system relies on sensor  12 . Sensor  12 , as schematically illustrated in FIG. 1, comprises any sensor capable of monitoring and/or analyzing the health, and particularly the PSD, of slurry. Sensors that can be used in the practice of this invention are available from a host of different manufacturers, e.g., the AccuSizer 780/OL or the NICOMP 380/ZLS from Particle Sizing Systems (PSS) of Santa Barbara, Calif.; the LSTM 230 from Beckman Coulter of Fullerton, Calif.; the Lab CMP Slurry Monitor from Colloidal Dynamics of New South Wales, Australia; and the Liquilaz-SO5 or the SlurryChek from Particle Measuring Systems of Boulder, Colo. This list of acceptable and capable sensors, while certainly illustrative, is not intended to be exhaustive.  
         [0027]    Although all of these sensors possess the ability to more than adequately monitor PSD, they can be fundamentally different in their manner of operation. Therefore, depending on the circumstances and manner of use, one sensor can be preferred over another for a given application. In certain embodiments of system  10 , the AccuSizer 780/OL is a preferred sensor. The AccuSizer, a single optical particle counter, is described in detail in U.S. Pat. No. 5,835,211 (Wells, et. al.), and it is incorporated into the present application by this reference as if fully set forth herein.  
         [0028]    Referring now to both FIGS. 1 and 2, multi-port valve manifold  14  comprises manifold body  20 , manifold intake  22 , manifold outlet  24 , and a plurality of multi-port valves  26   a - h  (collectively  26 ). As shown in FIG. 2, manifold  14  has a top  28  and a bottom  30 . In a preferred embodiment, manifold  14  is “vertically oriented” such that top  28  is vertically disposed above bottom  30  when the manifold is incorporated and/or employed within system  10 . When manifold  14  is vertically oriented, manifold intake  22  is proximate top  28  and manifold outlet  24  is proximate bottom  30 . As described in more detail below, flushing of manifold  14  is often enhanced when manifold  14  is vertically oriented. The pressure within manifold  14  will vary over the operation of the sampling system particularly during flushing (e.g., rinsing) operations.  
         [0029]    Manifold body  20  comprises a structural member (e.g., a tube, a pipe, a channel, or the like) that has and defines internal surfaces or walls (not shown). Manifold body  20  is capable of permitting various fluids (e.g., liquids, gases, slurries, etc.) to flow and/or pass through it.  
         [0030]    Manifold intake  22  and manifold outlet  24  are connected to manifold body  20  proximate top  28  and bottom  30 , respectfully, (i.e., at opposing ends) of manifold  14 . Manifold intake  22  can deliver flushing liquid into manifold body  20  by receiving the liquid from supply line  32 . The flushing liquid flows from and through supply line  32  to dividing point  33 . At dividing point  33 , the flushing liquid can be divided into two steams such that at least a portion of the flushing liquid flows through pressure valves  34  and  36 , through manifold intake  22 , and into manifold body  20  and manifold  14 . Manifold outlet  24  expels flushing liquid and other substances from manifold body  20  and manifold  14 . Therefore, the flushing liquid can pass through manifold  14 , and preferably, capture those other substances remaining in the manifold. The flushing liquid, as well as other substances, are then discharged through manifold outlet  24  into manifold discharge line  38 , through safety valve  40 , and passed to either sensor line  39  or drain line  41 . As such, the flushing liquid and other substances are either delivered to sensor  12  or system drain  18 .  
         [0031]    Although manifold  14  as shown in FIGS. 1 and 2 is equipped with eight multi-port valves  26  (e.g., three-way valves), any number of the multi-port valves can be used. In an exemplary embodiment, a pneumatic, eight-port, three-way valve manifold from Saint-Gobain Performance Plastic of Wayne, N.J. (formerly Furon Company) may be suitably employed as manifold  14 . In the embodiment of FIG. 2, each of multi-port valves  26   a - h  comprises an intake port  42   a - h  (collectively  42 ), an outlet port  44   a - h  (collectively  44 ), and a body port  46   a - h  (collectively  46 ) (schematically shown in FIG. 1).  
         [0032]    Referring to FIG. 1, intake ports  42   a - h  can be connected as desired to either a slurry supply line  48 , a drain line  50 , or a bottle sample line  52 . In a preferred embodiment, intake ports  42   a - f  are each associated with a slurry supply line  48  and, therefore, can receive slurry from one of the respective slurry supply lines when the intake port is actuated or open. Thus, various samples of slurry can, in preferred embodiments, be selectively received into manifold  14  through one of intake ports  42   a - f  within valves  26   a - f.    
         [0033]    Intake ports  42   g - h  can be connected as desired to either drain line  50  or bottle sample line  52 . In a preferred embodiment, as shown in FIG. 1, intake port  42   g  actually functions as an outlet (despite being labeled as an intake port). Thus, if necessary or desired, intake ports can be employed as outlet ports, and vise versa. Although illustrated in FIG. 1 as unconnected and/or unused, outlet ports  44   g - h  can be, if desired, connected to drain line  50  and bottle sample line  52 , respectively, in lieu of the lines being connect to intake ports  42   g - h.    
         [0034]    Intake port  42   g , in one embodiment, is associated with drain line  50 , and can, therefore, permit the discharge of air, gas pockets, flushing liquid, slurry, and other substances from manifold  14  when the intake port is actuated or open. As such, intake port  42   g  can, and often does, operate as a vent for manifold  14 . When operating as a vent, intake port  42   g  is typically located proximate top  28  of manifold  14 .  
         [0035]    Intake port  42   h , in one embodiment, is associated with bottle sample line  50 , and can, therefore, receive slurry from bottle transfer station  16  when the intake port is actuated or open. Bottle transport station  16  permits a sample of slurry from a remote location and/or unconnected CMP system to nonetheless be introduced into manifold  14  and, consequently, to sensor  12 . In other words, slurry from bottle transfer station  16  can be selectively introduced into manifold  14 .  
         [0036]    Bottle sample station  16  comprises bottle  54  and pump  56 . Pump  56  can be operated to draw slurry from bottle  54  such that a slurry sample can be delivered, through slurry sample line  52 , to manifold  14 . The delivered slurry sample from sample line  52  can be received by intake port  42   h  of valve  26   h . In an alternative embodiment, an aspirator or other device capable of transporting a fluid (e.g., flushing liquid, slurry, nitrogen gas, and the like) may be substituted for pump  54 . Referring again to FIG. 1, outlet ports  44   a - f  are each associated with a slurry discharge line  58  and, therefore, can discharge slurry through one of the respective slurry discharge lines  58  when the outlet ports are actuated or open. Thus, various samples of slurry can be selectively expelled from manifold  14  through one of outlet ports  44   a - f  within valves  26   a - f . In preferred embodiments, slurry is substantially continuously flowed from each slurry supply line  48  into an associated valve  26  and then discharged from the valve through an associated respective discharge line  58 . As such, the slurry is not permitted to settle and/or precipitate in valves  26  and slurry lines  48 ,  58 .  
         [0037]    Each body port  46   a - h  is integral or secured to, and associated with, manifold body  20 . As such, each valve  26  is provided with a conduit (e.g., corridor) to manifold body  20 . Therefore, when body ports  46  are actuated or open, any ultra pure water entering manifold  14  through manifold intake  22  can enter into each of valves  26  and, likewise, any slurry entering manifold  14  through one of intake ports  42   a - f  can enter into manifold body  20 . In other words, valves  26  and manifold body  20  are in fluid communication with each other. Therefore, as shown in FIG. 1, slurry can be discharged from manifold  14  through manifold outlet  24  and/or through one of outlet ports  44   a - f , as desired.  
         [0038]    Should slurry be expelled from manifold  14  through manifold outlet  24 , the slurry can travel through discharge line  38  until encountering safety valve  40 . During sampling and monitoring of slurry, safety valve  40  can be actuated or open to direct the slurry through sensor line  39  such that the slurry flows into, or proximate, sensor  12 . As such, slurry can be monitored and/or analyzed by sensor  12 . However, during rinsing, flushing, and pulsing, safety valve  40  can be actuated or open to direct slurry through drain line  41  where the slurry can be discharged from system  10  through system drain  18 .  
         [0039]    Prior to this invention, slurries were typically moved throughout slurry lines by employing, for example, one or more pumps. The pumps in conventional systems are selectively operated to push or pull the slurry through the system such that the slurry is transported from a source to a desired locale. However, the use of pumps can be expensive and impractical, especially when slurry is made available from more than one source. Therefore, instead of system  10  employing numerous, expensive, and maintenance-prone pumps, the system utilizes aspirator  60  to transport slurry from plurality of slurry lines  48 .  
         [0040]    Turning to FIG. 3, aspirator  60  comprises an aspirator body  62  (e.g., an elongate tube, a cylinder, and the like) defining a channel  64  within and through the aspirator, an aspirator intake  66  and an aspirator outlet  68  at opposing ends  70  of the aspirator body, and an aspirator suction port  72  disposed between the aspirator intake and the aspirator outlet and proximate a constricted portion  74  of the channel. Baffles  75  or like devices, as well as aspirator body  62 , can used and/or configured to form the constricted portion  74  of channel  64  within aspirator body  62 .  
         [0041]    Supply line  32  includes an upstream line  77  and a downstream line  79 . Upstream line  77  extends from aspirator  60  to dividing point  33  and from dividing point  33  to fluid source  76 . Upstream line does not, however, include that portion of supply line  32  that extends from dividing point  33 , passed valve  34 , and on to manifold inlet  22 . Downstream line  79  extends between aspirator  60  and system drain  18 . When aspirating fluid is delivered by fluid source  76 , the aspirating fluid can flow through both upstream and downstream lines  77 ,  79  such that the aspirating fluid travels from the fluid source to system drain  18 .  
         [0042]    In a preferred embodiment, upstream line  77  includes fluid supply valve  78 . Fluid supply valve  78  can be selectively actuated to permit or deny the aspirating fluid to flow from upstream line  77  to downstream line  79 . Therefore, fluid supply valve  78  can control the flow of aspirating fluid through aspirator  60 .  
         [0043]    In a preferred embodiment as shown in FIGS. 1 and 3, upstream line  77  is secured to aspirator intake  66  and downstream line  79  is secured to aspirator outlet  68 . Therefore, aspirating fluid travelling through fluid supply line  32  is permitted to flow through channel  64  within aspirator body  62  of aspirator  60 .  
         [0044]    Suction port  72  of aspirator  60  is preferably secured to sensor line  39 . As such, suction port  72  is in fluid communication with sensor  12 , discharge line  38 , sensor line  39 , manifold  14 , and the plurality of slurry supply lines  48 . Thus, slurry can be provided by one of slurry supply lines  48 , enter manifold  14 , travel through manifold discharge line  38 , sensor line  39 , pass through or by sensor  12 , and arrive at suction port  72  of aspirator  60 .  
         [0045]    Upon reaching suction port  72 , slurry can pass into aspirator body  60 , enter channel  64 , and combine and/or mix with the aspirating fluid flowing through the channel. Thereafter, the slurry or mix of slurry and aspirating fluid can be expelled from aspirator  60  at aspirator outlet  68 , pass through downstream line  79 , and be removed from system  10  by system drain  18 .  
         [0046]    In operation, as illustrated in FIG. 4, a procedure  80  for drawing fluid (e.g., a slurry) into system  10 , and particularly manifold  14  and sensor  12 , is outlined. When procedure  80  for drawing the fluid is initiated  82 , a determination  84  of whether an aspirating fluid (e.g., ultra pure water) has been introduced into aspirator  60  is made. If the aspirating fluid has not been introduced, fluid supply line  32  (FIG. 1) is opened  86  by actuating fluid supply valve  78  (FIG. 1). With fluid supply valve  78  opened, the aspirating fluid is introduced into, flows through, and is discharged from aspirator  60 .  
         [0047]    After the aspirating fluid has been introduced into aspirator  60 , a determination  88  of whether the aspirating fluid is expelled from aspirator  60  is made. If no aspirating fluid is expelled, a vacuum, partial vacuum, negative pressure, reduced pressure, and/or suction (collectively “suction”) is not produced, created, and/or generated  90  at suction port  72 . However, if the aspirating fluid is expelled, suction is produced  92  at suction port  72  and can be used to draw fluid.  
         [0048]    Suction created  92  at suction port  72  preferably draws, pulls, and/or biases a selected fluid from one of fluid delivery lines  48 . To draw the selected fluid, manifold  14  is operated such that one of intake ports  42   a - f  within one of multi-port valves  26  is opened. When this occurs, the selected fluid can be drawn from within the corresponding fluid delivery line  48  such that the fluid begins to fill  94  manifold  14 .  
         [0049]    As the selected fluid continues filling manifold  14 , a determination  96  as to whether the manifold has been filled with the fluid is made. If manifold  14  has not been substantially or at least partially filled with the drawn fluid, the flow of aspirating fluid (i.e., introduction and expulsion of the aspirating fluid into, through, and from aspirator  60 ) is maintained. In other words, the creation of suction is perpetuated and the fluid continues  98  to be drawn into manifold  14 . If, however, manifold  14  has been completely or partially filled with the fluid, the fluid can discharge from the manifold at manifold outlet  24 . Fluid discharged from manifold outlet  24  travels through manifold line  38  (FIG. 1) and arrives at, and enters, sensor  12 .  
         [0050]    Since sensor  12  can be considerably more delicate and fragile than manifold  14 , the rate at which the fluid is drawn into and through sensor  12  is often reduced in comparison to the rate at which fluid is drawn into manifold  14 . This is accomplished by reducing the rate (e.g., velocity) of aspirating fluid passing through aspirator  60 . When the velocity of aspirating fluid is reduced, a weaker and/or smaller suction is produced at suction port  72 . The weaker suction causes the velocity of the drawn fluid to decrease. The decreased velocity of the drawn fluid permits sensor  12  to be filled slower than manifold  14 . As such, sensor  12  can be filled with the drawn fluid without damaging or injuring the sensor, fouling the calibration of the sensor, and the like. Of course, when the rate of fluid drawn into the sensor is slowed, the rate of fluid entering manifold  14  is correspondingly reduced.  
         [0051]    As fluid enters sensor  12 , a determination  102  whether the sensor has been filled with the drawn fluid is made. If sensor  12  has not been substantially or at least partially filled with the drawn fluid, the flow of aspirating fluid is maintained. Therefore, the creation of suction is perpetuated and the fluid continues  104  to be drawn into sensor  12 . If, however, sensor  12  has been completely or partially filled with the fluid, the drawing of the fluid can be terminated. To terminate the drawing of the fluid, the flow of the aspirating fluid is discontinued by, for example, activating valve  78  and/or valve  34 .  
         [0052]    With the drawn fluid having been delivered into sensor  12 , the sensor is permitted to operate. Operation of sensor  12  can provide and/or generate data or output regarding the health of the fluid, including particle size distribution. Thereafter, the fluid can, when desired, discharge from sensor  12  through drain line  41  and be expelled from system  10 .  
         [0053]    In exemplary embodiments, after sensor  12  has been at least partially filled  102  with the fluid a determination  106  whether the fluid contains excess gas pockets is made. If the fluid does contain an unacceptable level or amount of gas pockets entrained or mixed with the fluid, the flow of the aspirating fluid can be continued  108 . By continuing  108  the flow of aspirating fluid, drawn fluid will continue to enter, and preferably flow through, sensor  12 . As such, the drawn fluid containing the gas pockets can be expelled from sensor  12 .  
         [0054]    After sensor  12  has been filled with fluid, and possibly after gas pockets have been removed and the sensor operated, procedure  80  for drawing fluid is complete  110 . In the context of system  10 , procedure  80  has permitted aspirator  60  to move, transport, and/or selectively deliver a slurry from one of slurry supply lines  48 .  
         [0055]    In a preferred embodiment, a single aspirator  60  is in operational association with a multi-port valve manifold  14  within system  10 . As such, single aspirator  60  and multi-port valve manifold  14  are operable, in combination, to permit a slurry to be selectively drawn from one of the plurality of supply lines  48  into the manifold, and thereafter, the sensor.  
         [0056]    Within system  10 , ultra pure water is typically employed as the aspirating and flushing liquid. However, other grades of water can also be used in various embodiments of this invention, such de-ionized water and demineralized water. Ultra pure water, as known and conventionally used in integrated circuit production facilities throughout the United States, itself is available in various grades, e.g., c-grade ultra pure water, semiconductor grade ultra pure water, and the like. The composition of ultra pure water does and can vary from producer to producer, but a common guideline for ultra pure water can be found in “Ultra Pure Water Monitoring Guidelines 2000” from Balazs Analytical Laboratory in Sunnyvale, Calif.  
         [0057]    Gases (e.g., nitrogen, oxygen, etc.) can also be employed, if desired, as the aspirating fluid. Furthermore, aspirator  60  can draw fluids other than one or more slurries, and manifold  14  can employ a variety of valves (e.g., a two-way valve, a four-way valve, and the like) in lieu of the three-way multi-port valves  26  illustrated in FIG. 1.  
         [0058]    Commonly-owned, co-pending U.S. patent application Ser. No. __/______ entitled “Flushing A Multi-Port Valve Manifold”, filed on Aug. 9, 2002, and U.S. patent application Ser. No. __/______ entitled “Next Generation Sampling And Measurement System For Use With Multiple Slurry Chemical Manifold”, filed on ___,_____, 2002, disclose other and various embodiments and components within a liquid sampling system that are compatible with a chemical-mechanical polishing system and, therefore, the contents and disclosure of these applications are incorporated into the present application by reference as if fully set forth herein.  
         [0059]    Despite any methods being outlined in a step-by-step sequence, the completion of acts or steps in a particular chronological order is not mandatory. Further, elimination, modification, rearrangement, combination, reordering, or the like, of acts or steps is contemplated and considered within the scope of the description and claims.  
         [0060]    While the aspirating method is described in terms of a multi-port valve manifold, and more specifically a multi-port valve manifold for use within a CMP slurry sampling system, the inventors contemplate that the method is equally applicable to other system components and may have other practical applications. Furthermore, while the present invention has been described in terms of the preferred embodiment, it is recognized that equivalents, alternatives, and modifications, aside from those expressly stated, are possible and within the scope of the appending claims.