Patent Publication Number: US-2006000509-A1

Title: Fluid flow control device and system

Description:
DESCRIPTION OF THE INVENTION  
      1. Field of the Invention  
      The present invention relates to a device for controlling the flow of fluids. Some exemplary aspects of the invention may relate to a flow rate control device configured to deliver fluids in semiconductor applications.  
      2. Background of the Invention  
      Devices presently available for controlling the flow of fluids are as numerous and varied as the different applications requiring such control. In some instances, fluid flow control can be a challenge. For example, in some applications, variations in the supply of fluid, or in the output conditions for that fluid, make it difficult to control the flow rate of the fluid precisely and repeatably. Such variations also make it difficult to adjust to fluctuations in fluid pressure and flow rate.  
      Due to these difficulties, some existing fluid flow control devices are not capable of both precise and repeatable fluid delivery. In fact, some existing fluid flow control devices have only a limited ability to compensate for variations upstream or downstream, and are not well suited to adjusting to fluctuating fluid conditions within the device. The limited capability of some current designs may be attributed to a number of factors. For example, the valves used in some devices may be sufficient for controlling the flow rate of the fluid but not particularly suitable for turning the flow on and off. Similarly, the components used in some devices may be capable of measuring the flow or pressure of fluid, but not very accurate due to fluctuations in fluid flow or pressure.  
      Some existing arrangements do not respond rapidly to changing flow control conditions. In some instances, a relatively appreciable delay exists between a change in flow rate and the detection of that change. As a result, a feedback control loop may only be as responsive as the flow meter or other measurement device used.  
      The present disclosure relates to a fluid flow control device that may at least partially avoid some or all of the aforementioned shortcomings of existing devices.  
     SUMMARY OF THE INVENTION  
      In the following description, certain aspects and embodiments of the present invention will become evident. It should be understood that the invention, in it&#39;s broadest sense, could be practiced without having one or more features of these aspects and embodiments. In other words, these aspects and embodiments are merely exemplary.  
      In accordance with one aspect of the present invention, a fluid flow control device may include an inlet for passing fluid into the device, and an outlet for passing fluid from the device. The fluid flow control device may also include a pressure regulating portion configured to receive the fluid and to deliver the fluid at a controlled pressure. The device may further include a flow control valving portion configured to receive the fluid delivered by the pressure regulating portion and to deliver the fluid at a controlled flow rate. In addition, the device may include a flow meter configured to measure the flow rate of the fluid, and a controller that controls at least the flow control valving portion according to at least the flow measured by the flow meter.  
      In another aspect, the pressure regulating portion of the device may include a pressure regulator and a regulator pilot valve that pneumatically controls the pressure regulator. The fluid flow control device may also include a pressure meter configured to measure the pressure of the fluid. The controller may control the regulator pilot valve, and may also be configured to control the regulator pilot valve according to at least the pressure measured by the pressure meter.  
      In yet another aspect, the flow control valving portion may include a flow control valve and a stepper motor controlling the flow control valve. For example, the controller may control the stepper motor, and the flow meter may measure the flow rate of fluid upstream from the flow control valve.  
      In still another aspect, the fluid flow control device may further include a means for inputting a desired fluid flow rate. The controller may control the flow control valve according to at least the desired fluid flow rate and the measured flow rate. The fluid flow control device may also include a display displaying the input, desired flow rate, and measured flow rate.  
      In a further aspect, the fluid flow control device may also include an outflow valve portion. This portion may be configured to apply suction via the outlet, and may further include an outflow valve (e.g., suck back valve) and a pilot valve pneumatically controlling the outflow valve. In some examples, the controller may control the outflow valving portion such that the outflow valving portion is changed from a fluid shut off position to a fluid flow position when the pressure regulating portion and the flow control valving portion are set for desired flow conditions.  
      In another aspect, the fluid flow control device may also include an inflow port for purge media and a purge media valving portion configured to control the flow of purge media through at least a portion of the device including at least the outlet. The purge media valving portion may include a purge media valve and a pilot valve pneumatically controlling the purge media valve.  
      In still another aspect, the fluid flow control device may also include a check valve configured to limit the flow of fluid from the device via the inlet. The device may also include an inflow port for a pressurized substance. The pressure regulating portion may be configured to be pneumatically controlled by using the pressurized substance.  
      In yet another aspect, the fluid flow control device may further include a pressure meter configured to measure pressure of the fluid. The controller may control the regulator pilot valve according to at least the pressure measured by the pressure meter.  
      A further aspect relates to a system for use in semiconductor processing. The system may include at least one fluid flow control device and at least one semiconductor processing tool. The semiconductor processing tool may receive fluid from the at least one fluid flow control device.  
      Yet another aspect relates to a system for use in the flow control of multiple fluids, including a first fluid flow control device and a second fluid flow control device. The devices may be in communication with each other. The first fluid flow control device may include a male connector and the second fluid flow control device may include a female connector configured to be coupled to the male connector.  
      The system may also include a bus module configured to enable the system to be in communication with a controlling unit. The bus module may include a female connector configured to be coupled to a male connector of the second fluid flow control device. In addition, each of the first and second fluid flow control devices may also include a means for inputting a desired fluid flow rate. Each of the devices may further include a display displaying the input desired flow rate and the measured flow rate.  
      One further aspect relates to a system for use in blending multiple fluids. The system may include a first fluid flow control device, a second fluid flow control device, and a mixer, wherein the outlet of each of the first and second flow devices is flow coupled to the mixer. For example, the system may be configured so as to control the first and second fluid flow control devices so as to provide the mixer with multiple fluid flows, wherein each fluid flow may have a controlled flow rate and a controlled flow rate duration.  
      Aside from the structural arrangements set forth above, the invention could also include a number of other arrangements such as those explained hereinafter. It is to be understood that both the foregoing description and the following description are exemplary only. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
      The accompanying drawings are incorporated in and constitute a part of this specification. The drawings illustrate exemplary embodiments, and together with the description, serve to explain some principles of the invention. In the drawings,  
       FIG. 1  is a side cut-away view of an embodiment of a fluid flow control device in accordance with the present invention;  
       FIG. 2  is a top cut-away view of the device of  FIG. 1 ;  
       FIG. 3  is a side view of an exemplary bus module for use with the device of  FIG. 1 ;  
       FIG. 4  is a side view of an embodiment of a system including a plurality of fluid flow control devices and a bus module;  
       FIG. 5  is a schematic view of the fluid flow control device of  FIG. 1 ;  
       FIG. 6  is a schematic view of an alternative embodiment of a system that includes fluid flow control devices being flow coupled to a component; and  
       FIG. 7  is a schematic view of an exemplary controller for the device of  FIG. 1 , the controller being in communication with a number of pilot valves, a regulator pilot valve, a stepper motor, a flow meter, and a pressure meter. 
    
    
     DESCRIPTION OF THE EMBODIMENTS  
      Reference will now be made in detail to several exemplary embodiments of the present disclosure. Wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or like parts.  
       FIGS. 1 and 2  show an embodiment of a fluid flow control device  5  including an inlet  120  and an outlet  125 . The inlet  120  may be fluidly connected to a fluid source  80  as shown in  FIG. 5 , and may be configured to allow a fluid to enter the fluid flow control device  5 . The fluid to be controlled by the fluid flow control device  5  may be any fluid having properties suitable for permitting flow of the fluid to be controlled. The fluid may be in a liquid, slurry, or gaseous form, and may have a relatively low viscosity and relatively low reactivity. Examples of some fluids include, but are not limited to, water, molten silicon, platinum, copper, or any other fluid, such as any other fluid used in the art of semiconductor manufacturing.  
      The outlet  125  may be fluidly connected to a component  81  as shown in  FIG. 5 , and may be configured to allow fluid to exit the fluid flow control device  5 . The component  81  may be a processing tool, or any other type of component configured to receive a fluid. The type of component  81  connected to the outlet  125  may depend on the application in which the fluid flow control device  5  is used. One exemplary component  81  is a semiconductor processing tool such as, for example, a spray-on tool, a spin-on tool, or a tool that dispenses fluid to a wafer processing chamber, vacuum chamber, or other environment known in the art.  
      The fluid flow control device  5  may further include a controller  115  (shown in  FIGS. 1 and 7 ), a pressure regulating portion  10 , a flow meter  25 , and a flow control valving portion  30 . The pressure regulating portion  10 , flow meter  25 , and flow control valving portion  30  are schematically illustrated in  FIG. 5 . The pressure regulating portion  10  may include a pressure regulator  15  and a regulator pilot valve  20 , and may be configured to receive a flow of fluid and deliver the fluid at a controlled pressure. The pressure regulator  15  may be, for example, a dome loaded pressure regulator or any other actuated pressure regulator known in the art. The pressure regulator  15  may be used to manage the pressure of a fluid downstream of the pressure regulating portion  10 , and may be responsive to the downstream pressure of the fluid through a feedback loop. The pressure regulator  15  may be a valve regulator that is configured to be pneumatically controlled.  
      As shown in  FIG. 5 , the regulator pilot valve  20  may be flow coupled to a pressurized substance source  65 . The regulator pilot valve  20  may control a pressurized flow of a pressurized substance from the source  65  to the pressure regulator  15  so as to pneumatically actuate the regulator  15 , and cause the regulator  15  to establish a particular fluid pressure downstream from the regulator  15 . The regulator pilot valve  20  may receive an electric signal from the controller  115  and, according to that signal, cause the pressure regulator  15  to be actuated a corresponding amount to supply a particular pressure of the pressurized substance and thereby actuate the pressure regulator  15 . Thus, the pilot valve  20  may accept an electric signal from the controller  115  and allow a regulated pressure of the pressurized substance to act on the pressure regulator  10  based on the electric signal. The pressure regulator  15  may respond to the pressurized substance by opening its orifice or other passage a corresponding amount, thereby regulating the pressure of the fluid downstream of the pressure regulating portion  10 . Thus, the fluid downstream of the pressure regulator  15  may have a managed pressure.  
      The pressurized substance may include, but is not limited to, nitrogen, oxygen, air, or any other gas known in the art to be suitable for operating pneumatic valves or other fluid flow control components.  
      Optionally, the fluid flow control device  5  may further include one or more pressure meters  24  as shown in  FIG. 5 . A pressure meter  24   a  may be located upstream of the pressure regulating portion  10 . In such an example, the pressure meter  24   a  may measure the pressure of the fluid before it enters the pressure regulator  15 , and may send a measurement signal to the controller  115  so as to enable the controller  115  to control the regulator pilot valve  20  according to that sensed pressure. This may enable the pressure regulator  15  to be adjusted for fluctuations in fluid pressure occurring upstream.  
      A pressure meter  24   b  may also (or alternatively) be located downstream of the pressure regulating portion  10 . The downstream pressure meter  24   b  may provide feedback to the controller  115  so as to enable the controller  115  to determine how well the pressure of the fluid is being controlled by the pressure regulator  15 . Similar to the upstream pressure meter  24   a , the pressure measured by the downstream pressure meter  24   b  may be used to control the pressure regulator  15 .  
      As shown in  FIGS. 1 and 5 , the flow control valving portion  30  of the fluid flow control device  5  may include a flow control valve  35  controlled by a motor  40 . The flow control valve  35  may receive fluid at a pressure controlled by the regulating portion  10 , and may regulate the flow rate of the fluid as it passes from the flow control device  5 . In some examples, the motor  40  controlling the flow control valve  35  receives an electric signal from the controller  115  and mechanically actuates the valve  35  to control the fluid flow rate based on that signal. The motor  40  could be a stepper motor, servo motor, or any other type of electric motor (e.g., precision electric motor) known in the art. Likewise, the flow control valve  35  could be any form of motor driven flow control valve commonly known in the art.  
      As mentioned above, and illustrated in  FIGS. 1, 2  and  5 , the fluid flow control device  5  may also include a flow meter  25 . After the fluid exits the pressure regulator  15  at a managed pressure, the flow meter  25  may measure the flow rate of fluid upstream of the flow control valve  35 . (Alternatively, the flow meter  25  may be located downstream of the flow control valve  35 .) The flow meter  25  may transmit a flow rate measurement signal to the controller  115 . The controller  115  may control the pressure regulating portion  10 , and the flow control valving portion  30 , according to the measured flow rate.  
      The flow meter  25  may be an ultrasonic flow meter capable of detecting the velocity of a flow in a calibrated tube through doppler shift or time of flight type measurements. Alternatively, the flow meter  25  may be a pressure differential type, a coriolis type, a vortex shedding type, a hot wire type, or any other type of flow meter known in the art.  
      In some examples, the flow meter  25  measures fluid flow downstream of the pressure regulator  15 , and sends a measurement signal to the controller  115 . The controller  115  receives the measurement signal in addition to possibly also receiving additional signals, such as a signal relating to a desired flow rate for the fluid. The controller  115  then sends corresponding pressure and flow signals to the regulator pilot valve  20  and motor  40  respectively. In this way, the flow meter  25  communicates with the controller  115  to form a continuous feedback loop to control other components of the fluid flow control device  5 .  FIG. 7  graphically illustrates an example of communication links between components that might be associated with the feedback loop.  
      In other examples (not shown), the feedback loop may include only the flow meter  25 , motor  40 , and controller  115 .  
      In a further example, the feedback loop may include both the flow meter  25  and the pressure meter  24   a  and/or  24   b  sending flow and pressure measurements respectively to the controller  115 . In such an example, the controller  115  may determine pressure and flow rate command signals according to that input as well as other input (e.g., the desired flow rate) and then send corresponding pressure and flow rate signals to the regulator pilot valve  20  and stepper motor  40  respectively.  
      In still another example (not shown), the fluid flow control device  5  may further include a second pressure regulating portion, like pressure regulating portion  10 , but located downstream of the flow control valving portion  30 . This second pressure regulating portion may serve as a back pressure regulator, isolating any variation in downstream pressure conditions from the flow and pressure meters  25 ,  24   a  and/or  246 .  
      The fluid flow control device  5  may further include an outflow valving portion  46 , including an outflow valve  45  optionally controlled by a pilot valve  50   c . The outflow valve  45  may be located near the outlet  125  of the fluid flow control device  5 . In some examples, the outflow valve  45  may be a suck back valve configured to apply suction via the outlet  125  that may draw at least some fluid into the device  5  via the outlet  125 . For some exemplary arrangements, the suction force may limit the formation of fluid droplets, residue, or other fluid-related issues associated with the component  81 . For example, when the component  81  is a semiconductor processing tool having a dispensing nozzle, sprayer, or some other form of fluid dispenser, the suck back valve may limit the formation of fluid droplets or residue associated with the fluid dispenser of the component. The suck back valve  45  may be actuated when a downstream process (e.g., a component  81  in the form of a semiconductor processing tool  81 ) stops demanding fluid. When actuated, the suck back valve  45  may draw at least some fluid back through the outlet  125  of the fluid flow control device  5 . As a result, the suck back valve  45  may limit flow related issues from arising while fluid flow is stopped. For example, when the component has a fluid spray nozzle, a suck back valve may ensure a clean spray of fluid from the spray nozzle when fluid flow is resumed.  
      In other examples, the outflow valve  45  may be a shut off valve or other type of two-way valve commonly known in the art of fluid control, and the valve  45  may be configured to prevent any fluid from flowing back into the device  5  once it has passed through the outlet  125 , or after the flow of fluid has stopped. The outflow valve  45  may also be configured to protect the components of the fluid flow control device  5  from damage caused by a downstream vacuum or other abnormal hydraulic condition.  
      In some examples, the outflow valve  45  may be set to open (e.g., via controller  115 ) only when the pressure regulating portion  10  and flow control valving portion  35  are controlled to place them in a position permitting a desired flow and a downstream process (e.g., component  81 ) demands the flow. The outflow valve  45  may be set to remain closed in all other conditions, and may also be set to close as soon as the downstream processing tool  81  stops demanding fluid. In other examples, the outflow valve  45  may allow the pressure regulator  15  and the flow control valve  35  to maintain consistent positions during start-up and stoppage of the fluid flow, and thus possibly reduce flow variation.  
      As shown in  FIG. 5 , the pilot valve  50   c  of the outflow valving portion  46  may be coupled to the pressurized substance source  65 , and may be configured to control a flow of the pressurized substance from the source  65  to the outflow valve  45 . The pilot valve  50   c  may be an electric solenoid valve, or any other type of open/close pneumatic valve known in the art. Alternatively, a stepper motor, servo motor, or any other type of electric motor (e.g., precision electric motor) known in the art may be used to actuate the outflow valve  45 , rather than the pilot valve  50   c . In examples where the outflow valve  45  is a suck back valve, the pilot valve  50   c , or alternatively one of the electric motors described above, may be used to control the amount and rate of suction that causes fluid to be drawn back into the device  5  via the outlet  125 .  
      To actuate the outflow valve  45 , the controller  115  may send an electric signal to the pilot valve  50   c , causing the valve  50   c  to allow the pressurized substance to pneumatically actuate the outflow valve  45 . In this way, the outflow valve  45  may be pneumatically actuated to either shut off the flow of fluid, permit fluid to flow out of the outlet  125 , or draw fluid back into the device  5 .  
      As shown in  FIGS. 2 and 5 , the fluid flow control device  5  may further include a check valve  75 . The check valve may be located at or near the inlet  120  of the fluid flow control device  5 , and may permit fluid to flow into the device  5  from the fluid source  80  while preventing fluid flow from the device  5  via inlet  120 . The check valve  75  may be any type of one-way flow valve known in the art.  
      The fluid flow control device  5  may further include a purge media valving portion  55  and a shut off valving portion  65 . The purge media valving portion  55  may include a purge media valve  60  controlled by a pilot valve  50   b . Similarly, the shut off valving portion  65  may include a shut off valve  70  controlled by a pilot valve  50   a . The purge media and shut off valves  60 ,  70  may be shut off valves or other types of two-way valves commonly known in the art of fluid control.  
      The purge media valve  60  may be fluidly coupled to a purge media source  90  and may be configured to permit a purge media to flow into the fluid flow control device  5  and possibly also pass through the outlet  125  and into tool  81 . The purge media may be a relatively pure purging media (e.g., cleaning agent) known in the art of fluid control such as, but not limited to, de-ionized water, distilled water, or diluted bleach. As shown in  FIG. 5 , the purge media valve  60  may be located upstream of the pressure regulating portion  10  in order to maximize the travel of the purge media through the fluid flow control device  5 . Thus, the purge media valving portion  55  may enable the purge media to flow through at least a portion of the device  5  including at least the outlet  125 . This flow of purge media may be desired before or after a fluid is delivered to a processing tool  81 , or before a new fluid is introduced into the device  5 .  
      The shut off valve  70  may be located upstream or downstream of the purge media valve  60  and may be configured to start and stop the flow of fluid to other components of the fluid flow control device  5 . The purge media valve  60  and the shut off valve  70  may be pneumatically controlled and actuated by pilot valves  50   b  and  50   a . The pilot valves  50   b  and  50   a  are coupled to the pressurized substance source  65  and are configured to control the flow of the pressurized substance from the source  65  to the purge media and shut off valves  60  and  70 , respectively. The pilot valves  50   b  and  50   a  may be electric solenoid valves, or other types of open/close pneumatic valves commonly known in the art. To actuate either of the valves  60 ,  70 , the controller  115  may send an electric signal to the respective pilot valve  50   b ,  50   c  causing the valve  50   b ,  50   c  to allow the pressurized substance to pneumatically actuate the purge media valve  60  or the shut off valve  70 .  
      As illustrated in  FIG. 2 , the fluid flow control device  5  may include an inflow port for purge media  140  and an inflow port for a pressurized substance  145 . The purge media inflow port  140  may be configured to accept a flow of purge media from the purge media source  90 , thus allowing the purge media to flow to the purge media valving portion  55  of the fluid flow control device  5 . In some examples, the purge media source  90  may include, but may not be limited to, a fluid tank, a sump, a fluid header, or any other type of purge media source container known in the art.  
      The pressurized substance inflow port  145  may be configured to accept a flow of the pressurized substance from the pressurized substance source  65 . The pressurized substance source  65 , may include, but may not be limited to, a high pressure gas tank, a pressurized gas header, a pressurized gas rail, or any other type of pressurized substance supply source container known in the art. The inflow port  145  may enable the pressurized substance to flow to any of the pilot valves  50   a ,  50   b ,  50   c  used in the device  5 , as well as the regulator pilot valve  20 .  
      As shown in  FIG. 4 , in an embodiment of the present invention, a number of fluid flow control devices  5  may be connected together so as to be in communication with each other. When connected in this way, the devices  5  may act together as a system for use in the flow control of multiple fluids. As shown in  FIG. 2 , each device may include a male and female connector  150 ,  155 , respectively usable for connecting one device  5  with another device  5  so as to be in communication with each other. In addition to providing a physical connection between adjacent pairs of devices  5 , the connectors  150  and  155  may also form an electric, pneumatic, fluid, and/or other connection between the devices  5 .  
      The system shown in  FIG. 4  may optionally include a bus module  95  configured to enable the system to be in communication with a controlling unit (not shown). For example, the controlling unit may be a personal computer, a server, a programmable logic controller or any other device known in the art to be used for the control of fluid control or other systems. To facilitate this communication, the bus module  95  may include an internet port  105  and an Ethernet port  110 . The bus module  95  may also include, for example, a device port, a power port, or any other connection port or structure known in the art for connecting electric components  
      In some alternative examples, a number of fluid flow control devices  5  may be connected, so as to be in communication with each other, without the use of a bus module  95 . For example, one or more components other than a bus module  95  may be used to enable a system of devices  5  to be in communication with a controlling unit.  
      As shown in  FIG. 4 , at least one bus module  95  may be used to control multiple fluid flow control devices  5 , and may be coupled to a male connector  150  of one of the devices  5  using a female  160  connector ( FIG. 3 ) configured for such a connection. When so connected, the bus module  95  may be in communication with all of the devices  5  in the system, and may be used to set desired flow rates. The bus module  95  may include a PC board  100  to facilitate this communication. In some examples, the PC board  100  may receive signals, pressure measurements, or flow measurements from any of the devices  5  in the system, or from a controlling unit or host. The PC board  100  may also process any of the signals or measurements received, and may transmit control signals to any of the devices  5  in the system. In this way, the bus module  95  may control the devices  5  in the system individually, or in conjunction with each other to supply a number of different fluids at different flow rates.  
      For example, in a semiconductor manufacturing process it may be desired to supply a number of fluids, each at different, and possibly varying, flow rates. To accomplish this dynamic blending of fluids, the bus module  95  may simultaneously control each device  5  so as to provide different flow rates for each supplied fluid. Each flow rate may be controlled to change with time. In such a scenario, each device  5  may supply a desired relative amount of fluid at a desired relative time in the semiconductor manufacturing process.  
      As shown in  FIG. 4 , each fluid flow control device  5  may further include a means for inputting a desired fluid flow rate  130 , and a display  135 .  FIG. 4  illustrates a reset and a set button, as well as up and down buttons as exemplary means for inputting a desired fluid flow rate  130 . However, it should be understood that many different forms of alternative input configurations are possible. For example, the means  130  may include, but may not be limited to, a digital control pad, a touch screen, a button panel, a keyboard or key pad, an internet connection, an Ethernet, devicenet or personal computer port, a wireless or infrared signal receiver, or any other commonly known means for inputting data to a device. In some examples, the tool  81  may supply information concerning a desired flow rate. In other examples, such as that shown in  FIG. 4 , a user may manually input a desired flow rate.  
      The controller  115  may be configured to control the flow control valving portion  30  and/or the pressure regulating portion  10  according to the desired flow rate inputted via the means for inputting a desired fluid flow rate  130 . For example, the controller  115  may control the components of the device  5  so as to maintain the measured fluid flow rate (measured by flow meter  25 ) as close as possible to the inputted desired flow rate.  
      The display  135  may display the inputted desired flow rate, the measured flow rate (measured by flow meter  25 ), or any other information associated with either the controller  115 , or the PC board  100 , a host, a user, or any of the components of the fluid flow control device  5 . The display  135  may be, but is not limited to, an LCD screen, a digital readout, a light array, a monitor, or any other type of display device used to output information. It is understood that the display  135  may be color or monochromatic, and that it may be of a different size, shape and/or configuration than that depicted in  FIG. 4 .  
       FIG. 6  schematically illustrates yet another embodiment of a system for use in semiconductor processing. Such an exemplary system may include at least one fluid flow control device (e.g., device  5   a  and device  5   b ) and at least one component  81  receiving fluid from the at least one device. It is understood that although  FIG. 6  shows two devices  5   a  and  5   b , any number of fluid flow control devices  5  could be used in such an embodiment to supply fluid to a single component  81  or to multiple components  81 .  
      In some examples, the component  81  shown in  FIG. 6  may be a semiconductor processing tool. Other possible examples may have a component other than a tool (e.g., other than a semiconductor processing tool). For example, the component  81  of  FIG. 6  may be a mixer (e.g., static mixer) and outlets of the devices  5   a  and  5   b  may be flow coupled to the mixer to provide blending of multiple fluids. For example, each device  5   a  and  5   b  may be controlled so as to provide different flow rates for each supplied fluid. Each flow rate may be controlled to change with time. In such an example, each device  5   a  and  5   b  may supply a desired relative amount of fluid at a desired relative time.  
      It will be apparent to those skilled in the art that various modifications and variations can be made to the structure described herein. Thus, it should be understood that the invention is not limited to the subject matter discussed in the specification. Rather, the present invention is intended to cover modifications and variations.