US20090016903A1

US20090016903A1 - Precision Pump With Multiple Heads

Info

Publication number: US20090016903A1
Application number: US11/778,002
Authority: US
Inventors: Raymond T. Savard; Greg Gray; Jack Laessle
Original assignee: Integrated Designs LP
Current assignee: Integrated Designs LP
Priority date: 2007-07-13
Filing date: 2007-07-13
Publication date: 2009-01-15

Abstract

A high purity, high precision pump capable of pumping more than one type of chemistry or process fluid without requiring cleaning or changing of surfaces contacting the processing fluid. The pump employs a single drive mechanism coupled in parallel with multiple pumping chambers, each capable of handling a different type of manufacturing fluid. The pump can be utilized as part of a single stage or multi-stage pump system.

Description

TECHNICAL FIELD OF THE INVENTION

The present invention relates generally to apparatus used in metering fluids with high precision, particularly in fields such as semiconductor manufacturing.

BACKGROUND OF THE INVENTION

Many of the chemicals used in manufacturing integrated circuits, photomasks, and other devices with very small structures are corrosive, toxic and expensive. One example is photoresist, which is used in photolithographic processes. In such applications, both the rate and amount of a chemical in liquid phase—also referred to as process fluid or “chemistry”—that is dispensed onto a substrate must be very accurately controlled to ensure uniform application of the chemical and to avoid waste and unnecessary consumption. Furthermore, purity of the process fluid is often critical. The smallest of foreign particles contaminating a process fluid causes defects in the very small structures formed during such processes. The process fluid must therefore be handled by a dispensing system in a manner that avoids contamination. See, for example, Semiconductor Equipment and Material International, “SEMI E49.2-0298 Guide For High Purity Deionized Water And Chemical Distribution Systems In Semiconductor Manufacturing Equipment” (1998). Improper handling can also result in introduction of gas bubbles and damage the chemistry. For these reasons, specialized systems are required for storing and metering fluids in photolithography and other processes used in fabrication of devices with very small structures.
Chemical distribution systems for these types of applications therefore must employ a mechanism for pumping process fluid in a way that permits finely controlled metering of the fluid and avoids contaminating and reacting with the process fluid. Generally, a pump pressurizes process fluid in a line to a dispense point. The fluid is drawn from a source that stores the fluid, such as a bottle or other bulk container. The dispense point can be a small nozzle or other opening. The line from the pump to a dispense point on a manufacturing line is opened and closed with a valve. The valve can be placed at a dispense point. Opening the valve allows process fluid to flow at the point of dispense. A programmable controller operates the pumps and valves. All surfaces within the pumping mechanism, lines and valves that touch the process fluid must not react with or contaminate the process fluid. The pumps, bulk containers of process fluid, and associated valving are sometimes stored in a cabinet that also houses a controller.
Pumps for these types of systems are typically some form of a positive displacement type of pump, in which the size of a pumping chamber is enlarged to draw fluid into the chamber, and then reduced to push it out. Types of positive displacement pumps that have been used include hydraulically actuated diaphragm pumps, bellows type pumps, piston actuated, rolling diaphragm pumps, and pressurized reservoir type pumping systems. U.S. Pat. No. 4,950,134 is an example of a typical pump. It has an inlet, an outlet, a stepper motor and a fluid displacement diaphragm. When the pump is commanded electrically to dispense, the outlet valve opens and the motor turns to force flow of displacement or actuating fluid into the pumping chamber, resulting in the diaphragm moving to reduce the size of the pumping chamber Movement of the diaphragm forces process fluid out of the pumping chamber and through the outlet valve.
Due to concerns over contamination, current practice in the semiconductor manufacturing industry is to use a pump only for pumping a single type of processing fluid or “chemistry.” In order to change chemistries being pumped, all of the surfaces contacting the processing fluid have to be changed. Depending on the design of the pump, this tends to be cumbersome and expensive, or simply not feasible. It is not uncommon to see processing systems that use up to 50 pumps in today's fabrication facilities.

SUMMARY OF THE INVENTION

The invention pertains generally to high precision pumps for use in dispensing process fluids in applications imposing constraints on handling due to corrosiveness of the process fluid, and/or due to sensitivity to contamination (e.g. from other fluids, particulates, etc.), bubbles and/or mechanical stresses. It is particularly useful for pumps in semiconductor processing operations.
In contradistinction to typical deployments of pumps in such applications, particularly those used for high-precision metering, an exemplary pump employing teachings of a preferred embodiment of the invention is capable of pumping more than one type of chemistry or process fluid without requiring cleaning or changing of surfaces contacting the processing fluid. The pump employs multiple pumping heads, each capable of handling a different type of manufacturing fluid. At least two of the pumping heads share a common actuating mechanism. Although a multi-headed pump might be larger when compared to a pump with a single head, utilizing fewer actuating mechanisms than pumping heads saves valuable space in crowded processing facilities, such as those used for fabricating semiconductor components, which use a large number of pumps. Since actuation mechanisms are sometimes the most complex part of a pump, fewer actuating mechanisms in a factory saves money and maintenance time.
Sharing a single actuating mechanism among multiple heads may seem undesirable, particularly for fluid metering applications. Having a shared actuation mechanism typically means that only one pumping head may be actuated at a time. However, in one exemplary embodiment, the multi-headed pump is capable of fast and frequent switching between pump heads. With actuation between pump heads capable of being switched quickly, there is little delay between demand for dispense and dispense in applications having very short dispense cycles due to relatively small amounts of fluid that are being dispensed.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view of a multiple head pump, shown in context of a high precision, high-purity fluid dispensing system.

FIG. 2 is an exploded view of an exemplary, preferred embodiment of a multiple head pump.

FIG. 3 is an exploded view from a different angle of the multiple head pump of FIG. 2.

FIG. 4 is a side view of the pump of FIGS. 2 and 3, assembled.

FIG. 5 is a cross section of the pump of FIG. 4, taken along section line 5-5.

FIG. 6 is a cross-section of the pump of FIG. 4 taken along section line 6-6.

FIG. 7 is an isometric view of the pump of FIG. 4.

FIG. 8 is a front view of the pump of FIG. 4.

FIG. 9 is a back view of the pump of FIG. 4.

FIG. 10 is view of an application of the pump of FIGS. 2-9.

FIGS. 11A, 11B and 11C constitute a flow chart of an exemplary dispense process of a controller for the pump of FIGS. 2-9.

FIG. 12 is a schematic diagram for one, preferred embodiment of a two-stage pumping system utilizing a multi-head pump.

FIG. 13 is a schematic diagram of an alternate of a two-stage pumping system utilizing a multi-head pump.

FIG. 14 is a schematic diagram of another alternate embodiment of a two-stage pumping system utilizing a multi-head pump.

FIG. 15 is a schematic diagram of an example of a two-stage pumping system utilizing two or more multi-head pumps.

DETAILED DESCRIPTION

FIG. 1 schematically illustrates one example of a high precision, multiple head dispense pump for pumping a plurality of different chemicals in a high purity application. A pumping head is a portion of a pump that, among other possible functions, contacts and applies force to the process fluid in order to move it. In a high precision, multiple head pump, more than one pumping head is actuated by a common actuating mechanism. In the illustrated example, a multiple head pump is used to dispense chemicals or process fluids from three separate bulk sources 101, 103 and 105 to each of three separate dispense points 107, 109 and 111, respectively. Each source and dispense point is coupled through a pump head 113, 115, or 117. Each pump head functions to move a predetermined amount of fluid from the source to the corresponding dispense point. Because each pump head functions independently and does not share with the other pump heads any surfaces that contact process fluids, each bulk source is permitted to be a different type of chemical. Output valves 119, 121, and 123 open and close output lines 120, 122, and 124, respectively, between the pump heads to their corresponding dispense points. Each is independently controlled by a controller (not shown) that coordinates opening of the valve with pump operation. Because the illustrated pump is employable to particular advantage in semiconductor manufacturing operations, where chemicals are pumped to a dispense point for dispensing onto a semiconductor wafer, the output lines in the illustrated example are coupled suck back valves 125, 127 and 129. After a dispense, a suck back valve is used to draw fluid back from a dispense tip, nozzle or similar element in order to prevent dripping.
In the illustrated example, the pumping heads move fluid by drawing it into a pumping chamber and then displacing it. Positive displacement is advantageous for applications requiring precise metering of fluid. The volume of each pumping chamber is increased to suck-in process fluid, and then decreased to push it out. A member that is used to change the volume of a chamber will be called a displacement member. A pumping chamber and displacement member can be implemented a number of different ways. One example includes a piston or piston-like device moving within a cylinder. Other examples include bellows, tubular diaphragms, and rolling diaphragms. The instant example contemplates use of a flexible diaphragm that cooperates with the walls of the pumping chamber to displace fluid. Moving the diaphragm in one direction increases the volume of the pumping chamber, and moving it another direction decreases the volume of the pumping chamber, thus displacing fluid from it. The diaphragms for pump heads 113, 115 and 117 are schematically illustrated in the figure as elements 131, 133 and 135, respectively.
A number of different arrangements can be used to ensure that fluid flows only in one direction through the pump head. In the illustrated example, the pump head includes an inlet (not indicated) for coupling the pump head to a process fluid source, such as sources 101, 103 or 105, and an outlet (not indicated) for coupling the pump head to a dispense point, such as dispense point 107, 109 or 111. The pumping chamber in the pump head has at least one opening, and preferably at least two openings, one being in communication with the inlet and the other in communication with the outlet. Fluid is drawn into the pumping chamber through the inlet opening and is expelled through the outlet opening. This allows for creation of a generally unidirectional flow of process fluid through the pumping chamber, which can assist in reducing pooling of process fluid and accumulation of contaminants in the pump head. The inlet and outlet of each pump head is coupled through valving that ensures, at least normal operation, that fluid flows into the pumping chamber only from the inlet and exits the pumping chamber only through the outlet.
The valving can take different arrangements, depending in part on the number of openings into the pumping chamber and other considerations. In the illustrated example, the valving is comprised of two valves. Check valve 137 ensures one-way flow from the inlet into the pumping chamber, and check valve 139 ensures one-way flow of process fluid exiting the chamber through the outlet. The check valves are self-actuating or lifting, which tends to reduce complexity by avoiding having to implement a mechanism for synchronizing their opening with the pumping action of the pump head. However, it might be advantageous in some circumstances, such as those described below, to incorporate valves whose opening can be independently controlled. Furthermore, use of check valves may not be appropriate for some applications. If the pumping chamber has only one opening, one example of suitable valving includes a three-way valve that selectively couples either the inlet or outlet to the opening, or closes the opening altogether, depending on the stroke of the pump. Other types of valving could be chosen to achieve the same functionality, although possibly at the expense of greater complexity and less reliability.
The plurality of pumping heads share a common actuation mechanism, represented in the figure by drive motor and piston assembly 135. An actuating mechanism includes a force generating component, such as a motor, and a coupling for communicating the force to a fluid displacement member. Sometimes, these components are one and the same. Examples of actuating mechanisms include mechanical, pneumatic and hydraulic mechanisms, and combinations of them. One example of a mechanical actuator is a driver motor coupled to a diaphragm through a purely mechanical coupling, such as a transmission or other mechanical linkage or piston. The linkage or piston converts the output of the motor into movement of the fluid displacement member. A hydraulic coupling can also be used, with the motor moving a piston, which in turn moves hydraulic fluid that pushes against the displacement member. In a purely pneumatic system, for example, gases under high pressure are used to move the displacement member.
In the illustrated example, the force generated by the common actuating mechanism is preferably applied in parallel, rather than serially, to each of the pump heads. Although applying the force in parallel will lead all pump heads to actuate simultaneously, avoiding serial application of the force reduces the complexity by avoiding a mechanism for selectively applying or switching the actuation force between the pump heads. Complexity tends to increase costs and reduce reliability.
In order to avoid undesirable, simultaneous actuation of all pump heads, yet maintain simplicity, the actuating mechanism in the illustrated example preferably utilizes a fluidic coupling for communicating forces from a motor or other force generating mechanism to the process fluid. The drive assembly for the actuation mechanism in the illustrated example includes a drive motor (not shown) for supplying force for moving the actuating fluid. The drive motor moves a displacement member (e.g. a piston) that, in turn, moves fluid in a manner that causes the pumping head to actuate. Actuating fluid is moved in and out of a chamber on the side of the diaphragm opposite the pumping chamber. Displaced actuating fluid moves into the pumping head, reducing the volume of the pumping chamber and pushing fluid out. Reverse movement of the displacement member causes the actuating fluid to flow from the pumping head, increasing the volume of the pumping chamber and consequently drawing in process fluid. If the fluid is not compressible at least at the pressures at which the pump functions (such fluid being referred to herein as incompressible), and only one pumping chamber is open, the amount of actuating fluid displaced by actuating assembly is proportional to the amount of process fluid displaced from within the pumping chamber.
Blocking flow of process fluid out of the pumping chamber of a pump head in effect blocks the flow of actuating fluid into the pump head, thus causing actuating fluid to be redirected to, and to flow into, another pump head without internal valving to redirect the fluid to different pump heads. Therefore, although internal valving could be used, it is not required in order to ensure only one head is pumping at a time. In this example, a preexisting valve at the outlet—a valve that would otherwise be present for this application—is sufficient, therefore allowing reduction in complexity and the size of the pump without a corresponding increase in the number of external valves that would otherwise be required. Furthermore, existing external valving can be utilized for blocking process fluid flow through the pump heads. In the illustrated example, which uses self-actuating check valves, output valves 119, 121 and 123 are selectively closed to block flow of fluid from the pump heads that are not intended to be pumping during actuation of the pump. The output valves may be located anywhere along the line carrying fluid from the pump head to the dispense point. A controllable valve can be substituted for one or both check valves, or used in addition to them, if an output valve is not available or if there is a preference not to use the output valve. However, this would be at the expense of more cost and complexity. Furthermore, other valving arrangements that are used to ensure one way flow of process fluid through the pump head, such as the three-way valve mentioned above, can also be used for this purpose.
When used for metering fluids, the pump is operated so that only one pump head is active at a time. All actuating fluid is thereby directed only into or out of the active pump. By allowing actuating fluid to flow only out of one pump head at a time, the amount of process fluid being pumped is determined from movement of the displacement member within the actuation mechanism. If more than one pump head is opened for pumping during actuation, a mass flow meter is coupled with the pump head to determine the amount process flowing out of the pump head. However, in applications such as semiconductor manufacturing, dispense cycles are short and demand for dispense from a particular dispense point is not constant and, in some cases, relatively infrequent. Given the absence of internal valving for redirecting the actuating fluid and the simplicity of the mechanism controlling flow of process fluid through a pump head, fast activation of pump heads is possible, thus allowing the actuating fluid to be, in effect, time multiplexed to the pump heads without unduly slowing dispensing.
Referring now to FIGS. 2 through 9, exemplary, single-stage pump 200 is comprised of an exemplary structure for the multi-head pump shown in FIG. 1, suitable for high purity applications, such as those in semiconductor manufacturing. The pump 200 includes, in this example, three pumping head structures 202, 204 and 206, which cooperate with a central body 208 to form respective pump heads. The heads are arrayed around a central axis of a central body 208. The central body 208 supports the pump heads and preferably also provides channels in the form of holes or passageways through the body for supplying hydraulic actuating fluid to each pump head. By integrally forming the fluid passageways as part the body, such as by machining a monolithic block, additional connections can be avoided, thus reducing the risk of a leak of actuation fluid. In high purity applications such as semiconductor fabrication, even the smallest leak contaminates the clean environment and is therefore very undesirable.
The body in the illustrated example possesses a square cross-section with four sides. Formed on three of the four sides are faces to which the pumping heads are coupled. The fourth side is used, in this example, to receive a pressure sensor 210. The pressure sensor is used to measure the pressure of hydraulic fluid within the actuation mechanism. Arraying the pumping heads at least partially around channels supplying hydraulic actuation fluid tends to result in more efficient utilization of space as compared to, for example, a configuration in which the heads are arranged in a linear fashion. However, other of the advantages of the exemplary pump illustrated in these figures can be achieved without the pumping heads being arrayed around the central axis. For example, the pumping heads can be arranged in a stacked configuration. More pumping heads can be coupled to the central body by increasing the cross-sectional size, increasing the number of faces disposed around a central axis of the central body, by reducing the size of the pumping heads, and/or by extending the body along its central axis. The size of the pumping head depends in part on the desired volume of the pumping chamber. Preferably, the size of the pumping chamber is such that multiple, incremental dispenses, in which only a portion of the process fluid within the pumping chamber is dispensed during a dispense cycle, are completed before having to draw in more fluid. A face need not be flat, but can be curved if desired. Thus, for example, the central body can have either a polygonal or a generally circular cross section. Although a circular cross-section may take up less space, flat faces have the advantage of a simpler fabrication and connection with the pumping head.
The central body preferably also houses, as in this example, at least one hydraulic actuation mechanism. The mechanism includes a fluid reservoir as well as a displacement element. In the illustrated embodiment, the actuation fluid reservoir is comprised of a cavity 207 (see FIG. 5) of circular cross-section formed within the center of the block forming body 208, and the displacement element is comprised of several elements functioning as a piston and generally designed by reference number 209. Placing the hydraulic actuation mechanism in the central body makes most efficient use of space and avoids external connections. However, all or part of the actuation mechanism could, alternatively, be located outside support body 208 and hydraulically coupled with the pumping heads, with the loss of certain advantages of the preferred embodiment, such as loss of compactness and greater complexity and risk of contamination from leaks due to increased numbers of connections. For example, if the axial length of a body is extended by joining multiple blocks, the actuation mechanism could, for example, be located in one of the blocks and hydraulically coupled with the other block through a passageway or external line.
In the illustrated embodiment, pumping head structures 202, 204 and 206 are coupled respectively with a face portion 211 formed on each of three side walls of body 208.
In each of the pumping head structures, diaphragm 212 extends across the face portions and cooperates with a pumping head to define a pumping chamber 214 on one side of the diaphragm, and with a depression 216 formed in the body, at the face portion, to define an actuating fluid chamber 218 on the opposite side of the diaphragm. In this preferred embodiment of the exemplary pump the diaphragm can be easily removed and replaced by removing the pumping head assembly. The diaphragm is sealed against the cooperating face of body by O-ring seal 220. Plate 222 attaches the diaphragm to the face of the body. Among other advantages, attaching the diaphragm with the plate allows the pump to be built and charged with actuation fluid—preferably a substantially incompressible fluid (at least at the pressures typically encountered in the application), such as glycol—prior to the pump heads being assembled with the body. The diaphragms are preferably made from a translucent material in order to permit visual identification of any air or gas bubbles within the actuation fluid prior to attaching the pump heads. Although one diaphragm per pump head is being used in the illustrated embodiment, two or more adjacent pump heads could instead use a different area of one, larger diaphragm, isolated by a seal or other structure so that process fluid does not leak between the pump heads. Vent line 223 permits air to be purged from the actuation fluid chamber 218 in each pumping head. Vent lines 223 are sealed with plugs that are not shown in the figures. Air entrapped in the actuation fluid and/or process fluid, pumping chamber, actuation fluid chamber, cavity 207, or any of the channels within the pump carrying the fluids, can also be detected by charging the pumping chambers with process fluid, closing each of them so that process fluid cannot flow out, pumping the actuation fluid and monitoring the pressure of the actuation fluid using pressure sensor 210. Because air bubbles are compressible, the measured pressure will be less than expected if a substantial amount of air is entrapped in the system.
Each pump head structure 202, 204 and 206 is an assembly that includes a pumping chamber cover 224 with a cavity or depression 226. The cover cooperates with the diaphragm 212 to form pumping cavity 214. O-ring 225 forms a seal between the cover 224 and the diaphragm mounting plate 216. Inlet orifice 228 and outlet orifice 230 extend through cover 224 for permitting flow of process fluid into and out of, respectively, the pumping chamber. The inlet orifice is located near the bottom of the pumping chamber so that fluid flows upward, against gravity, when the pump is in a normal operating position, toward the outlet orifice. This arrangement and the elongated form of the pumping chamber tends to reduce pooling of process fluid within the pumping chamber and encourages migration of bubbles toward the outlet to assist with purging. The generally curved shape of the depression 226 and obtuse angles at the junctions of straight surfaces within the pumping cavity avoid sharp corners in which process fluid and micro-bubbles might collect and be difficult to purge, thus further reducing the risk of entrainment of bubbles during normal operation.
Each pump head structure includes connectors for connecting lines carrying process fluid into and out of the pump head. In order to save space, the connectors are preferably oriented in a direction that is generally parallel to the elongated axis of the pumping chambers and the body 208. If oriented with their axes perpendicular to the axis of the body 208, the pump 200 would occupy more space in lateral directions, and additional space would be required to accommodate the process fluid lines that will be connected to the inlet and outlet connectors. Inlet fitting 232 and outlet fitting 234 are threaded into a connector block 236. The illustrated inlet and outlet fittings are examples of flare type fittings typical in semiconductor manufacturing. They are intended to be representative generally of fittings for connecting lines to the pump. Other types of fittings can be used, depending on the application. Other examples of high purity fittings used in the semiconductor industry include Super Type Pillar Fitting® and Super 300 Type Pillar Fitting® of Nippon Packing Co., Ltd., Flowell® flare fittings, Flaretek® fittings from Entegris, “Parflare” tube fittings from Parker, LQ, LQ1, LQ2 and LQ3 fittings from SMC Corporation, Furon® Flare Grip® fittings and Furon® Fuse-Bond Pipe from Saint-Gobain Performance Plastics Corporation. The connector block 236 and the cover 224 are, in this example, fabricated separately and assembled into a head assembly. However, the assembly could be fabricated using fewer or more components.
The connector block 236 includes a passageway that carries fluid from the inlet into the connector block toward the inlet orifice 228 of the pumping chamber. In this example, the passageway is formed by a channel 238 formed on the surface of a block and a cooperating gasket 240. The gasket also seals the pumping chamber cover 224 with the connector block 236. A hole 242 allows fluid to flow into channel 244 (see FIG. 5) defined through the pumping chamber cover 224. Channel 244 terminates at inlet orifice 228.
In the illustrated example, a one-way check valve 246 is integrated into the connector block that allows fluid to flow only from the inlet fitting 232 to the pumping chamber. The check valve is inserted into the same bore as the inlet fitting 232. It is comprised of an orifice plate 248 and an umbrella-shaped valve 250 that cooperates with the orifice plate 248. The valve's stem attaches the valve to the orifice plate. Fluid flowing under pressure through the holes in the orifice plate, toward the valve, tends to cause the edges of the valve to curl up or lift, while the center of the valve remains stationary. The valve has an inverted shape. When it is assembled, the stem pulls the edges of the valve against the orifice plate, thereby creating a seating force that presses the perimeter of the valve against the plate. This forms a good seal. More details about this particular type of check valve can be found in commonly assigned U.S. patent application Ser. No. 11/612,408, filed on Dec. 18, 2006, which is incorporated herein by reference.
The connector block also includes a passageway that carries fluid exiting pumping chamber 214 to the outlet connector 234. It also incorporates a one-way check valve 252 that allows fluid flow in the direction of the outlet connector. Check valve 252 is substantially similar to check valve 246. It includes an orifice plate 254 that sits in a recess 255 formed on the back of pumping chamber cover 224. Umbrella-shaped valve 256 is attached to the orifice plate 254. Fluid flowing out of the pumping chamber 214, through the outlet orifice 230, flows through the check valve 252 and into a passageway that connects with outlet fitting 234. That passageway is formed in part by channel 258, formed in one surface of connector block 236, and cooperating gasket 240. Segment 260 (see FIG. 6) of the passageway connects to a bore into which inlet fitting 234 is screwed. An initial portion of channel 258 preferably forms a volume large enough to accommodate deflection of the edges of the valve and flow of fluid from around the edges of the valve without restricting the flow.
Incompressible actuating fluid is stored in the central chamber or cavity 207 of the actuating mechanism. When piston 209 translates within the cavity 207, passageways 264 communicate fluid between the cavity and an actuating fluid chamber 218, associated with each of the pumping heads 202, 204 and 206. Fluid is capable of moving in parallel between the cavity 207 and each actuating fluid chamber 218. Therefore, actuating fluid will, unless otherwise stopped, flow into each actuating chamber 218 when the piston displaces actuating fluid from the cavity 207. Similarly, actuating fluid will, unless otherwise stopped, flow out of the actuating fluid chamber 218 associated with each pump head when the piston is retracted, causing the actuating fluid to be drawn into the cavity 207.
Assuming that the pumping chamber 214 and the corresponding actuating fluid chamber 218 contain no gas, air or other compressible substance, flow of fluid through a given passageway is controlled in the illustrated embodiment by whether the diaphragm is permitted to move in the corresponding pump head. If it cannot move, actuating fluid will tend not to flow in either direction through the passageway between the cavity 207 and the actuating fluid chamber 218 that is associated with that diaphragm. Whether a diaphragm moves depends on whether process fluid can be drawn into the pumping chamber 214 during flow of actuating fluid out of the actuating fluid chamber 218, and whether it can flow out of the pumping chamber during flow of the actuating fluid from the cavity 207 and into the actuating fluid chamber 218. Given that process fluid can only flow in one direction through the pumping chamber of the illustrated embodiment, opening and closing a valve (not shown in these figures) located in the outlet flow path for process fluid from the pumping chamber 214 will thus determine whether the diaphragm can be moved to displace the process fluid in the pumping chamber, which in turn determines whether actuating fluid flows into the actuating fluid chamber for the given pump head. By opening the outlet of only one pumping head, all the actuating fluid caused by displacement of piston 209 will be forced to flow into only the actuating fluid chamber of the pump head with the open outlet. The volume of actuating fluid displaced by movement of piston 209 will equal the volume of process fluid displaced by the diaphragm of the pump head with the open outlet. In other words, there is a linear relationship between the movement of the piston and the volume of process fluid pumped.
As process fluid is always permitted to flow into each of the pumping chambers in the illustrated embodiment, actuating fluid will always flow from each actuating fluid chamber 218 during retraction of piston 209, at least until the diaphragm reaches the surface of the wall forming depression 216 for that particular process fluid chamber. The wall forming depression 216 preferably includes a channel 217 to ensure that the diaphragm is pulled evenly against the wall. Thus, the illustrated embodiment of pump 200 will simultaneously recharge, or will recharge in parallel, each pumping chamber in the pump, regardless of the number of pumping heads.
Piston 209 include a sliding seal 262. Displacement of the piston within cavity 207 is preferably controlled by a stepper motor 264, which turns a drive screw 266. Clamp 268 attaches the drive screw to output shaft 270 of the motor. Thrust bearing 272 prevents the drive shaft from axially loading the output shaft of the motor. The threads on the drive screw 266 couple with threads on the inside of the piston 209. The angular position of the piston is fixed by a guide 274, which is clamped to the piston and cooperates with slot 276 to prevent rotation of the piston. Turning the drive screw moves the piston. Other types of mechanisms for translating the piston could, however, be substituted. An optical sensor 278 detects when guide 274, and thus piston 209, is at a predetermined limit during upstroke. This is used to calibrate the pump. Cover 280 seals an opening that allows access to the cavity 207 for assembly and cleaning.
For semiconductor and other high purity applications, it is preferred that all surfaces of the pump that contact the process fluid are made of non-contaminating or non-reacting material. One example of such a material is polytetrafluoroethylene, which is sold by DuPont under the trademark Teflon®.
An exemplary application of multiple head dispense pump 200 is illustrated by FIG. 10. In this application, the pump 200 is used to dispense 3 different types of process fluids, used in the fabrication of integrated circuits, onto a semiconductor wafer 300. Each process fluid is stored in a bulk container 302. The respective containers are numbered 302A, 302B and 302C. Each container supplies process fluid to one of the dispense heads 202, 204 or 206. In this example, bulk container 302A supplies pump head 204 through supply line 304A; bulk container 302B supplies pump head 202 through supply line 304B; and bulk container 302C supplies pump head 206 through supply line 304C. Each of the supply lines is connected to the inlet fitting 232 (see FIG. 2) of the pump head that it supplies with process fluid.
The outlet fitting 234 (see FIG. 2) of each of the pump heads 202, 204 and 206 is connected, respectively, to outlet lines 306B, 306A, and 306C. In this example, each outlet line is connected in series with a separate one of the filters 308A, 308B or 308C. Filtering the process fluid is optional. Furthermore, fewer than all of the process fluids can be filtered, if desired. Each of the filters is connected to a separate purge valve 310A, 310B and 310C, respectively. The outlets of the filters are connected to dispense valves 312A, 312B and 312C, respectively. The dispense valves may include, optionally, integrated suck-back valves. The outlet of each of the dispense valves is connected to a nozzle, from which process fluid is dispensed onto wafer 300. Not all of the heads on pump 200 need to be used to service one wafer. They may also be used, for example, to supply process fluid to more than one wafer.
Operation of the pump 200 and dispense valves 312 is controlled by a controller 314. Preferably, the controller is programmable, microprocessor-based, but could be implemented using any type of analog or digital logic circuitry. The same controller can be used to control more than one multi-head pump. The controller typically receives a demand for dispense signal from a manufacturing line, where the wafer is being processed. However, the control processes can be implemented in the line controller or other processing entity associated with the fabrication facility.
FIGS. 11A, 11B, and 11C are high level flow diagrams for an exemplary dispense mode control process of exemplary multi-head pump 200 of FIGS. 2-9 for the application illustrated in FIG. 10. The process takes place within the controller 314 when the controller is in a dispense mode. In this example, the controller receives a request for dispense in the form of a signal sent to one of its interfaces. There are three interfaces in this example, corresponding to pump heads 202, 204 and 206 (see FIGS. 2-9). Each interface may include a physical communication interface. It may also store certain state information. Alternatively, the interfaces may also be implemented entirely logical or virtually. For example, the controller may communicate with one or more tracks or other processing entities over one or more shared physical mediums, using addressable messages. The signal would be comprised of a message that identifies directly or indirectly a dispense head, such as by a logical port, address, or other identifier that the controller can map to a particular dispense head.
When the controller receives a request for dispense of process fluid, as indicated by blocks 402, 404, and 406, the controller signals the other interfaces that the pump is busy and sets a flag indicating that dispense is active for that interface. Thus, if the request is received on interface 1, the controller communicates to interfaces 2 and 3 at step 408 that the pump is busy, so that production tracks or lines that communicate with it know that dispense is not available. It also sets at step 410 a stored flag, dispense 1, active. Similarly, if a dispense request is received on interface 2, a pump busy signal or state is communicated to interfaces 1 and 3 at step 412 and a dispense 2 flag is set active at step 414. Finally, if the request for dispense is received on interface 3, the pump busy signal or state is communicated to interfaces 1 and 2 at step 416, and the dispense 3 flag is set active at step 418.
As indicated by decision step 420, the controller determines whether there is an optional dispense delay set up or programmed for that interface. In a dispense delay, as indicated by steps 422, 424 and 426, the dispense valve corresponding to the active dispense flag is opened for a predetermined period of time prior to the pump being actuated. This might be used in applications in which, for example, it is desirable for the rate of dispense to start slow and then increase. If there is no dispense delay, the pump is started at step 428. The controller can be set up or programmed to open the dispense valve corresponding to the active dispense flag either immediately or after a predetermined or programmed delay, as indicated by steps 430, 432 and 434.
Once the dispense valve is opened and the pump is started, the controller actuates the pump so that a preset or otherwise determinable amount of process fluid is dispensed at a predefined rate or rates (the rate can be varied by, or be a function of, time and/or other parameters, if desired), as indicated by step 436. In the embodiment illustrated in FIGS. 2-9, the controller steps the stepper motor 264 at a rate corresponding to the desired rate(s). The number of steps corresponds to the volume of process fluid to be dispensed. Once that volume is dispensed, the pump stops and the dispense valve corresponding to the active dispense flag is closed, as indicated by steps 442, 444, 446, 448, 450 and 452. The closing of the dispense valve can, optionally, be delayed, as indicated by steps 438 and 440. Once the active dispense valve is closed, the corresponding suck-back valve is operated, as indicated by steps 454, 456, 458, 460, 462, 464, 466, 468 and 470, after an optional delay, as indicated by steps 472 and 474. The state of the suck-back is communicated to the interface corresponding to the active dispense flag, as indicated by steps 456, 462 and 468.
Once suck-back is completed, an end of dispense state or signal is communicated to the interface with the active dispense flag, as indicated by steps 472, 474, 476, 478, 480, and 482. The controller then waits for the interface to release the dispense, as indicated by steps 484, 486, and 488. The release occurs when the track or line controller signals acknowledge the end of dispense.
When the interface releases the dispense, the controller clears all dispense flags at step 490, communicates to all dispense interfaces that the pump is busy at step 492, and recharges the pump at step 494. To recharge the pump, the stepper motor is stepped in a direction opposite of the direction it is stepped for dispense, until the pumping chambers in each pump are fully charged. In the embodiment illustrated in FIGS. 2-9, an optical sensor 278 indicates when guide 274 is in a fully retracted position. This indicates that the piston 209 is retracted to the point at which enough of the actuating fluid is sucked out of each of the actuating fluid chambers 218 that the pumps are charged with the desired amount of process fluid. Typically, this will be when the diaphragm 212 is pulled close to the wall of depression 216 that partially forms the actuating fluid chambers. The dispense cycle then ends at step 498, and the state of the controller returns to a start state indicted by step 400, in which the pump waits for a dispense request.
Referring now to FIGS. 12, 13, 14 and 15, another application multi-headed pump, such as the ones discussed above in connection with FIGS. 1-11, is in a two-stage pumping system. Four examples 500, 502, 504, and 505 of two-stage pumping systems are illustrated, respectively, in FIGS. 12, 13, 14 and 15. Example 505 demonstrates two, two-stage pumps 505 arranged in parallel, with first stages that share one, common actuation system, and second stages sharing a second, common actuation system. Each of the remaining examples is of just a two-stage pumping system, with both stages sharing the same actuation mechanism.
In each of the examples of a two-stage pumping system, a pumping chamber 506 is used as a first stage, and pumping chamber 508 is used as a second stage. The volume of each pumping chamber is changed to draw in and expel process fluid using a diaphragm, bellows, rolling diaphragm, tubular diaphragm or other arrangement. In examples 500, 502, and 504, pumping chambers 506 and 508 can be two different heads of a multi-headed pump, such as the one described in FIGS. 2-9. In the two, two-stage pumping systems 505, the first stage pumping chambers 506 of the respective two stage pump systems are, in the example, implemented with different heads on the same multi-headed pump. Similarly, the second stage pumping chambers 508 of these two, two-stage pumping systems are implemented by different heads on a second multi-headed pump. Additional heads on each multi-head pump could also be used to drive the same stage of more than two, two-stage pumps, if desired.
The first stage of the pump is used to pull fluid from a source 509 and push it to a filtering system, generally designated by filter 510. The second stage is used for pulling the fluid from the filtering system and dispensing it, in a metered fashion, onto, for example, a wafer 512. Fill valve 513 is opened to allow fluid to be drawn from the source 509 and into the first stage, and then closed when the first stage pumps. The fill valve can be alternatively implemented as a check-valve. The filtering system typically includes a vent, controlled in these examples by valve 514, and a drain, controlled in these examples by valve 516. Each of the examples also includes a dispense valve 518, for controlling dispensing, and an optional suck-back valve 520. Each of the two-stage pumping systems in the examples includes a valve 522 for preventing reverse flow of processing fluid from the pumping chamber 508. A check valve is preferred. Two-way and other types of valves can be substituted for the check valve, but they will need to be opened and closed synchronously with the operation of the pumping system, thereby complicating the control processes. Each two-stage pumping system includes a recirculation loop 521 that is opened and closed by recirculation valve 523. The two, two-stage pumping systems 505 shown in FIG. 15 can be used to pump different types of process fluids to the same station, and onto the same wafer, as shown, in which case process fluid sources 509 would contain different types of process fluid. The two pumping systems can also be used to pump process fluids to multiple different stations.
The two- stage pumping systems 500 and 505 shown in FIGS. 12 and 15 also include reservoir 524 in series between the filter 510 and the second stage pumping chamber 508 of each of the systems. The reservoir is optional, and is only necessary if the filtering system cannot also act as a reservoir for receiving process fluid being pumped by the first stage.
In all examples 500, 502, 504, and 505, multiple pumping chambers are driven by a single drive mechanism, which in these examples is comprised of stepper motor 526, turning a screw 528, which in turn causes translation of a piston within cylinder 530. In the two- stage pumping systems 500, 502, and 504, each drive mechanism is coupled in parallel to pumping chambers 506 and 508. In the two-stage pumping systems 505, shown in FIG. 15, the first stage pumping chambers 506 are driven by a common drive mechanism, and the second stage pumping chambers 508 are driven by a second, common drive mechanism.
For semiconductor and other high purity applications, it is preferred that all surfaces of the pump that contact the process fluid be made of non-contaminating or non-reacting material. One example of such a material is polytetrafluoroethylene, which is sold by DuPont under the trademark Teflon®. Other examples include high density polyethylene and polypropylene, and PFA (perfluoroalkoxy copolymer resin).
The drive mechanism operates substantially similarly to the actuation mechanism described in connection with FIGS. 1-9. Actuation of a drive mechanism causes actuation fluid to flow through fluid conduits extending between drive mechanisms and each of the two pumping chambers in a manner described below. The conduits can be comprised of tubing, formed as passageways through blocks of materials, or other structures capable of communicating actuation fluid, and combinations of the foregoing. Surfaces contacting the actuation fluid do not need to be of a type for maintaining high-purity, such as those required for the process fluid.
In two- stage pumping systems 500, 502 and 505, shown in FIGS. 12, 13, and 15, the drive mechanisms are coupled to pumping chambers through valves 532 and 534. Valves 532 and 534 are used to control the flow of actuation fluid between the drive mechanism of each of the two pumping chambers to which it is coupled. They permit selectively directing flow of actuating fluid only to one of the plurality of pumping chambers to which the pumping mechanism is coupled. A single three-way valve can be substituted for the two valves 532 and 534. Valves 532 and 534 are omitted from the two-stage pumping system 504 of FIG. 14. Instead, a first stage output valve 536 is inserted to permit selectively closing and opening the outlet of the pumping chamber. Closing the first stage pumping chamber prevents actuation fluid from displacing processing fluid from the chamber, thus effectively “locking” it against actuation, and thereby making it unnecessary to utilize valves 532 and 534. Although a coupling that utilizes valves 532 and 534 may complicate system timing, they do not have to be suitable for high-purity applications, like valve 536 would need to be. Therefore, they will be less expensive. Furthermore, valves 532 and 534 may enhance dispense accuracy. Therefore, although optional, they might be preferred for some applications.
The operation of the two-stage pumping systems, which is described below, is controlled by one or more controllers, executing predetermined control routines to open and close the various valves and to cause turning of the motor of the drive mechanism.
Referring now only to FIGS. 12-13, operation of each of the two- stage pumping systems 500 and 502 will be first described. Assuming that each system is completely primed and full of process fluid, all valves are closed and a unit is ready to process a first wafer. Dispense valve 518 is opened. Actuation fluid valve 534 for the second stage is also opened. Drive motor 526 turns the drive screw 528, moving the piston in cylinder 530. The piston advances forward, pushing actuation fluid out of the cylinder. Blocked by closed first stage actuation fluid valve 532, the actuation fluid moves through valve 534 and into pumping chamber 508, causing movement of a process fluid displacement member, such as some type of diaphragm. As the actuation fluid moves in, it displaces an equal volume of process fluid. The process fluid exits the chamber. It is blocked by check valve 522, so it flows through output valve 518 and out a dispense tip. Output valve 518 is then closed after the dispense is finished. The motor 526 reverses direction, pulling the piston backward, which in turn pulls the actuation fluid back in to the cylinder 530. This pulls the process fluid displacement member, causing the pumping chamber to increase in volume and to pull on the process fluid. New process fluid is drawn from the reservoir 524 or, if there is no reservoir, from filter 510, to replenish the dispensed amount. All valves close unit is back at rest. Either a sensor detects a low fluid level in the reservoir (or in the filter if there is no reservoir), or the first stage automatically refills the reservoir (or filter) after every dispense. In either case, first stage pumping chamber 506 is already full of process fluid. Actuation fluid valve 532 is opened and the motor 526 is actuated to cause actuation fluid to be pushed into pumping chamber 506. This forces the process fluid through filter 510 and into reservoir 524, if present. Fluid can be pushed through the filter at any desired flow rate. Once the reservoir 524, or if there is no separate reservoir, the filter, is full, the motor reverses, fill valve 513 opens, and fresh process fluid is drawn into the pumping chamber 506 as the volume of the pumping chamber increases due to actuating fluid being pulled from it. The unit is now recharged and ready for the next dispense. If desired, the process fluid can be recirculated, filtered, and returned to the source bottle. To do this, valve 523 is opened so the process fluid can be pumped back to the source through line 521. The recirculation process keeps the fluid from becoming stagnant.
The two-stage pumping system of FIG. 14 functions similarly. However, instead of valves 532 being closed during dispensing, valve 536 is closed during dispensing and recharging of pumping chamber 508. Since the pumping chamber 506 is full of process fluid and both valves 513 and 536 are closed, actuation fluid is effectively blocked from flowing into or out of the pumping chamber 506, forcing it to flow only between pumping chamber 508 and cylinder 530. During actuation of the first stage pumping chamber 506, actuation fluid is forced to flow to the first stage pumping chamber, and away from the second stage pumping chamber 508, by having the second stage pumping chamber fully charged and closing dispense valve 518.
Each of the two, two-stage pumping systems 505 in FIG. 15 works in a manner substantially similar to those of the preceding examples. However, each drive mechanism drives only one of the two stages and therefore they must be operated in a coordinated fashion. One drive mechanism is coupled to the first stages of the two pumping systems, which are respectively represented by pumping chambers 506, and selectively actuates either one of the two first stages in a manner like that described above in connection with FIGS. 12-14. Similarly, the second drive mechanism selectively actuates either of the pumping chambers 508 in the manner described. This arrangement, thus, confers the benefits of having fewer drive mechanisms than pumping chambers, yet enables the two stages to be operated independently. Stages of more than two pumps can be driven by the same drive mechanism, if desired.
Valves 532 and 534 are optional for each of the drive mechanisms, although they can provide greater control and accuracy. Furthermore, no valve 536 on the outlet of the first stage pump is required when valves 532 and 534 are omitted, since the first stage of each of the two pumping systems is being operated independently of the second stage of each of the two pumping systems. However, if the reservoirs or filters of the respective of the two-stage pumping systems 505 need to be filled independently, then an output valve, like valve 536, would be desirable to have.
The foregoing description is of an exemplary and preferred embodiment of a multiple dispense head pump employing at least in part certain teachings of the invention. The invention, as defined by the appended claims, is not limited to the described embodiments. Alterations and modifications to the disclosed embodiments may be made without departing from the invention. The terms used in this specification are, unless expressly stated otherwise, intended to have ordinary and customary meaning and are not intended to be limited to the details of the illustrated structures or the disclosed embodiments. None of the descriptions in the present application should be read as implying that any particular element, step, or function is an essential element which must be included in the claim scope. The scope of patented subject matter is defined only by the allowed claims. Moreover, none of these claims are intended to invoke paragraph six of 35 USC §112 unless the exact words “means for” or “steps for” are followed by a participle.

Claims

1. A pump system for use in selectively dispensing a plurality of different process fluids, comprising:

a plurality of process fluid displacement mechanisms;

one or more actuation mechanisms coupled with the plurality of displacement mechanisms for actuating each of the plurality of process fluid displacement mechanisms, the number of process fluid displacement mechanisms being greater than the number of actuation mechanisms; and

valves in fluid communication with the plurality of process fluid displacement mechanisms operable for controlling flow of process fluid from the plurality of fluid displacement mechanisms during dispensing and for permitting flow of process fluids into each of the plurality of fluid displacement mechanisms during recharging of pumping means.

2. The pump system of claim 1, further comprising a controller for operating the valves to permit flow of process fluid from only one of the plurality of fluid displacement mechanisms at a time during dispensing.

3. The pump system of claim 1, wherein each of the plurality of fluid displacement mechanisms receives process fluid from a different one of a plurality of fluid sources.

4. The pump system of claim 1, wherein each of the plurality of fluid displacement mechanisms is in fluid communication with a different one of a plurality of nozzles.

5. The pump system of claim 1, wherein more than one of the plurality of dispense points is located at a single dispense point.

6. The pump system of claim 1, wherein the actuating mechanism includes a hydraulic actuating mechanism.

7. A pump system for use in handling a plurality of different process fluids in applications imposing constraints on handling process fluid, comprising:

an actuation mechanism for pumping actuating fluid;

a plurality of pump chambers, each including at least one process fluid inlet and at least one process fluid outlet to the pumping chamber;

a diaphragm for dividing each pump chamber and for separating process fluid from actuation fluid; and

each pump chamber in fluid communication with the actuation mechanism through at least one channel permitting unrestricted flow into the pump head of substantially incompressible actuation fluid, the at least one process fluid outlet coupled to at least one valve for selectively preventing and allowing the flow of process fluid through the pump head;

whereby operation of the hydraulic actuating mechanism to displace actuating fluid causes actuating fluid to flow only into each of the plurality pump chambers coupled with opened at least one valve, resulting in pumping.

8. The pump system of claim 7, wherein the at least one fluid channel permits unrestricted flow from the pump chamber and into the actuating mechanism of actuation fluid.

9. The pump system of claim 7, wherein actuation mechanism is comprised of a displacement mechanism for moving actuation fluid coupled with an incremental advancement mechanism.

10. The pump system of claim 7, wherein the displacement mechanism is comprised of a piston translated by a screw turned by a stepper motor.

11. The pump system of claim 7, further comprising a controller for selectively operating the at least one valve to which each of the plurality of pump heads is coupled to selectively allow and stop flow of process fluids.

12. The pump system of claim 7, wherein the at least one valve includes a controllable valve for selectively opening and closing a line coupled with the outlet.

13. The pump system of claim 12, further comprising a one-way check-valve coupled with the process fluid outlet of each of the plurality of pump chambers for allowing fluid to flow only in one direction out of the pump head, and a one-way check valve coupled with the process fluid inlet of each of the plurality of pump chambers for allowing fluid to flow only in one direction into the pump head.

14. The pump system of claim 7, wherein each of the plurality of pump chambers is coupled with a process fluid nozzle for dispensing process fluid.

15. The pump system of claim 14, wherein the process fluid nozzles coupled to plurality of pump chambers are located and arranged on a processing line for dispensing process fluids onto the same semiconductor substrate.

16. The pump system of claim 7, wherein the outlet of each of the plurality of pump chambers is in fluid communication with a filter for filtering the process fluid.

17. The pump system of claim 7, wherein the actuating mechanism is mounted within a central structure, and the plurality of pump chambers is at least partially formed by at least one removable pump head structure supported on the central structure.

18. The pump system of claim 12, further comprising a plurality of pump head structures, the plurality of pump head structures being arrayed around the support structure.

19. The pump system of claim 7 comprised of a plurality of actuation mechanisms, wherein the number of the plurality of pump chambers exceeds the number.

20. A pump for use in concurrently handling a plurality of different process fluids in applications imposing constraints on handling process fluid, comprising:

a structure forming a central reservoir for storing substantially incompressible actuation fluid, in which a displacement member is disposed for moving actuating fluid into and out of the central reservoir;

a plurality of pump chambers, each pump chamber including at least one process fluid inlet and at least one process fluid outlet to a pumping chamber;

each of the plurality of pump chambers including at least a portion of a diaphragm dividing the pump chamber and separating actuation fluid from process fluid from within the pump chamber;

at least one channel permitting unrestricted flow between the pump chamber and the reservoir of substantially incompressible actuation fluid; and

at least one valve coupled with the at least one process fluid outlet coupled for preventing and allowing the flow of process fluid through the pump chamber;

whereby operation of the hydraulic actuating mechanism to displace actuating fluid causes fluid to flow only into pump chambers with outlets coupled with at least one valve that is opened.

21. The pump of claim 20, further comprising, for each pump chamber, a one-way check-valve coupled with the process fluid outlet for allowing fluid to flow only in one direction out of the pump chamber, and a one-way check valve coupled with the process fluid inlet of each of the pump heads for allowing fluid to flow only in one direction into the pump chamber.

22. The pump of claim 20, wherein the displacement mechanism is coupled with an incremental advancement mechanism.

23. The pump of claim 20, wherein the central structure has formed thereon a plurality of faces, to which a plurality of pump heads are respectively mounted, each face cooperating with one of a plurality of the pump heads in order to form one of the plurality of pump chambers, the diaphragm for each pump chamber being mounted between respective ones of the plurality of pump heads and the central structure.

24. The pump of claim 20 wherein the plurality of pump chambers are integrated with, and arrayed around, the structure forming the reservoir.

25. In a pump comprised of an actuation mechanism for pumping actuating fluid and a plurality of pump chambers, each in fluid communication with the actuation mechanism through at least one fluid communication channel permitting unrestricted flow of actuating fluid between the pump chamber and actuating mechanism, each of the plurality of pump chambers including at least one process fluid outlet coupled to at least one outlet valve, a method comprising:

charging each of the plurality of pump chambers with process fluid;

displacing a predetermined amount of actuating fluid from the actuating mechanism;

selectively opening for process fluid flow at least one outlet for one or more of the plurality of pump chambers; and

closing the at least one outlet for each of the other ones of the plurality of pump chambers in order to create back-pressure with the process fluid in the pump chambers that tends to prevent actuation fluid from flowing into the pump chamber;

whereby actuating fluid flows only into the ones of the plurality of pump chambers with the at least one outlet opened, resulting in displacement of process fluid from the pumping chamber.

26. The method of claim 25, wherein each pump chamber includes a diaphragm separating process fluid from actuation fluid.

27. The method of claim 25, wherein the actuation mechanism is comprised of a displacement mechanism for moving actuation fluid coupled with an incremental advancement mechanism.

28. The method of claim 25, wherein the displacement mechanism is comprised of a piston translated by a screw turned by a stepper motor.

29. The method of claim 25, wherein the pump further comprises a one-way check-valve coupled with the process fluid outlet for each pump head for allowing fluid to flow only in one direction out of the pump head, and a one-way check valve coupled with the process fluid inlet of each of the pump heads for allowing fluid to flow only in one direction into the pump head.

30. The method of claim 25, wherein the actuating mechanism is mounted within a central structure, and each of the pumping chambers is formed at least in part by a pump head structure supported on the central structure.

31. The method of claim 30, wherein the plurality of pump heads are arrayed around the support structure.

32. The pump of claim 30, wherein the central structure has formed thereon a plurality of faces, to which the pump head structure is mounted, each face cooperating with the pump head in order to form one of the plurality of pump chambers; and wherein each pump chamber includes a diaphragm for each pump chamber mounted between respective ones of the pump head and the central structure.

33. A substrate with structures formed in part by using a pump, the pump being comprised of an actuation mechanism for pumping actuating fluid and a plurality of pump chambers, each in fluid communication with the actuation mechanism through at least one fluid communication channel permitting unrestricted flow of actuating fluid between the pump chamber and actuating mechanism, each of the plurality of pump chambers including at least one process fluid outlet coupled to at least one outlet valve; wherein using the pump comprises:

charging each of the plurality of pump chambers with process fluid;

selectively opening at least one outlet for one or more of the plurality of pump chambers;

displacing a predetermined amount of actuating fluid from the actuating mechanism for delivery to a dispense point near the substrate;

34. The substrate of claim 33, wherein each pump chamber includes a diaphragm separating process fluid from actuation fluid.

35. The substrate of claim 33, wherein the actuation mechanism is comprised of a displacement mechanism for moving actuation fluid coupled with an incremental advancement mechanism.

36. The substrate of claim 33, wherein the displacement mechanism is comprised of a piston translated by a screw turned by a stepper motor.

37. The substrate of claim 33, wherein the pump further comprises a one-way check-valve coupled with the process fluid outlet for each pump head for allowing fluid to flow only in one direction out of the pump head, and a one-way check valve coupled with the process fluid inlet of each of the pump heads for allowing fluid to flow only in one direction into the pump head.

38. The substrate of claim 33, wherein the actuating mechanism is mounted within a central structure, and each of the pumping chambers is formed at least in part by a pump head structure supported on the central structure.

39. The substrate of claim 38, wherein the plurality of pump heads are arrayed around the support structure.

40. The substrate of claim 38, wherein the central structure has formed thereon a plurality of faces, to which the pump head structure is mounted; each face cooperating with the pump head in order to form one of the plurality of pump chambers; and wherein each pump chamber includes a diaphragm for each pump chamber mounted between respective ones of the pump head and the central structure.

41. The substrate of claim 33, wherein each of the plurality of pump chambers is in fluid communication with a separate one of a plurality of nozzles oriented for dispensing process fluid onto the substrate.