U.S. patent application number 14/802314 was filed with the patent office on 2015-11-12 for precision pump with multiple heads.
The applicant listed for this patent is Integrated Designs L.P.. Invention is credited to Brian Kidd, John Laessle, John Vines.
Application Number | 20150322938 14/802314 |
Document ID | / |
Family ID | 43827699 |
Filed Date | 2015-11-12 |
United States Patent
Application |
20150322938 |
Kind Code |
A1 |
Laessle; John ; et
al. |
November 12, 2015 |
Precision Pump With Multiple Heads
Abstract
A pump for one or more different process fluids is provided
including a pumping chamber having a process fluid inlet and outlet
coupled to a process fluid valve on each pumping chamber for
selectively preventing and allowing flow of process fluid through
the pumping chamber. An actuation mechanism for pumping actuating
fluid to actuating fluid chambers is provided that is in
communication with the actuating fluid chambers to permit flow into
each actuating fluid chamber of incompressible actuating fluid. A
diaphragm separates each pumping chamber from an associated
actuating fluid chamber for separating process fluid from actuating
fluid. The actuation mechanism is removable by a quick disconnect
that provides for disconnection of the activation mechanism without
affecting process fluid. Operation of the actuation mechanism to
displace actuating fluid causes actuating fluid to flow only into
each actuating fluid chamber having an opened process fluid valve,
resulting in pumping.
Inventors: |
Laessle; John; (Plano,
TX) ; Vines; John; (Dallas, TX) ; Kidd;
Brian; (Frisco, TX) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Integrated Designs L.P. |
Carrollton |
TX |
US |
|
|
Family ID: |
43827699 |
Appl. No.: |
14/802314 |
Filed: |
July 17, 2015 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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13951857 |
Jul 26, 2013 |
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14802314 |
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13670083 |
Nov 6, 2012 |
8535021 |
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13951857 |
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12687784 |
Jan 14, 2010 |
8317493 |
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13670083 |
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11938408 |
Nov 12, 2007 |
8047815 |
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12687784 |
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11778002 |
Jul 13, 2007 |
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11938408 |
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Current U.S.
Class: |
417/273 |
Current CPC
Class: |
F04B 43/06 20130101;
F04B 53/16 20130101; F04B 43/0736 20130101; F04B 53/10 20130101;
F04B 43/067 20130101; F04B 13/02 20130101; F04B 15/04 20130101;
F04B 43/02 20130101; F04B 53/20 20130101; F04B 49/065 20130101;
F04B 45/04 20130101 |
International
Class: |
F04B 43/02 20060101
F04B043/02; F04B 53/20 20060101 F04B053/20; F04B 53/16 20060101
F04B053/16; F04B 45/04 20060101 F04B045/04; F04B 53/10 20060101
F04B053/10 |
Claims
1-30. (canceled)
31. A pump for use in handling at least one of a plurality of
different process fluids, comprising: a plurality of pumping
chambers, each pumping chamber adapted to independently pump one of
the plurality of different process fluids, each pumping chamber
including a process fluid inlet and a process fluid outlet, a
process fluid valve associated with each pumping chamber, the
process fluid outlet coupled to the process fluid valve for
selectively preventing and allowing the flow of process fluid
through the pumping chamber; a filter for receiving process fluid
from a first one of the plurality of pumping chambers, wherein said
filter removes particulates from the process fluid to form a
filtered process fluid; a reservoir for receiving said filtered
process fluid, wherein a second one of said plurality of pumping
chambers pumps filtered process fluid from said reservoir storing
filtered process fluid; a plurality of isolation valves, each
isolation valve for selectively preventing and allowing the flow of
an actuation fluid; and a recirculation pathway with an associated
recirculation valve, said recirculation valve downstream of said
second one of the plurality of pumping chambers and the
recirculation pathway for recirculating the filtered process fluid
to said first one of the plurality of pumping chambers.
32. A pump for use in handling at least one of a plurality of
different process fluids, comprising: a plurality of pumping
chambers, each pumping chamber adapted to independently pump one of
the plurality of different process fluids, each pumping chamber
including a process fluid inlet and a process fluid outlet, a
process fluid valve associated with each pumping chamber, the
process fluid outlet coupled to the process fluid valve for
selectively preventing and allowing the flow of process fluid
through the pumping chamber; a filter for receiving process fluid
from a first one of the plurality of pumping chambers, wherein said
filter removes particulates from the process fluid to form a
filtered process fluid, said filter storing filtered process fluid,
a second one of the plurality of pumping chambers for pumping
filtered process fluid from said filter storing filtered process
fluid; a plurality of isolation valves, each isolation valve for
selectively preventing and allowing the flow of an actuation fluid;
and a recirculation pathway with an associated recirculation valve,
said recirculation valve downstream of said second one of the
plurality of pumping chambers and the recirculation pathway for
recirculating the filtered process fluid to said first one of the
plurality of pumping chambers.
33. A pump for use in handling at least one of a plurality of
different process fluids, comprising: a plurality of pumping
chambers, each pumping chamber adapted to independently pump one of
the plurality of different process fluids, each pumping chamber
including a process fluid inlet and a process fluid outlet, a
process fluid valve associated with each pumping chamber, the
process fluid outlet coupled to the process fluid valve for
selectively preventing and allowing the flow of process fluid
through the pumping chamber; a plurality of isolation valves, each
isolation valve for selectively preventing and allowing the flow of
an actuation fluid; wherein each isolation valve is a proportional
control valve to enable dispensing out of a plurality of pumping
heads simultaneously, at at least one flow rate, using a single
actuating mechanism.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation of U.S. application Ser.
No. 13/951,857 filed on Jul. 26, 2015, entitled Precision Pump With
Multiple Heads, pending, which is a continuation of application
Ser. No. 13/670,083, now U.S. Pat. No. 8,535,021, filed on Nov. 6,
2012, entitled Precision Pump With Multiple Heads, which is a
continuation application of U.S. application Ser. No. 12/687,784,
now U.S. Pat. No. 8,317,493, filed on Jan. 14, 2010, entitled
Precision Pump with Multiple Heads, which is a continuation-in-part
application of U.S. application Ser. No. 11/938,408, filed on Nov.
12, 2007, entitled Precision Pump with Multiple Heads which is a
continuation-in-part application of U.S. application Ser. No.
11/778,002, filed on Jul. 13, 2007, entitled Precision Pump with
Multiple Heads, abandoned.
FIELD OF THE INVENTION
[0002] 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
[0003] 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. Even the smallest foreign particles contaminating a
process fluid cause 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.
[0004] 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/or 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 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 the 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,
containers of process fluid, and associated valving are sometimes
stored in a cabinet that also house a controller.
[0005] 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 in 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
(Bailey et al.) 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 a displacement or
actuating fluid into the actuating fluid chamber, resulting in the
diaphragm moving to reduce the size the pumping chamber. Movement
of the diaphragm forces process fluid out the pumping chamber and
through the outlet valve.
[0006] 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.
[0007] A dispensing apparatus that supplies process chemicals from
different sources is shown in U.S. Pat. No. 6,797,063 (Mekias).
Here, the dispensing apparatus has two or more process chambers
inside of a control chamber. The volume of the process chambers
increases or decreases by adding control fluid to or removing
control fluid from the control chamber. The use of valving at the
inlets and outlets of the process chambers, in combination with a
pressurized fluid reservoir that controls fluid into and out of the
control chamber controls the flow of dispensed fluid through the
process chambers.
[0008] One highly desirable feature of a precision pump not
heretofore know is the ability to separate and remove components of
the pump for maintenance or repair without breaking into the
process fluid flow lines that are attached to one or more pump
chamber heads. This would include avoiding opening of any seals in
the process fluid flowpath either into, through, or out of the
pump.
BRIEF SUMMARY OF THE INVENTION
[0009] 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.
[0010] In contradiction 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. Multiple pumping heads share a common actuation mechanism.
Although each pump might be larger when compared to a pump with a
single head, utilizing fewer actuation mechanisms than pumping
heads saves very 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 actuation
mechanism in a factory saves money and maintenance time.
[0011] Sharing a single actuation 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 embodiment
the exemplary 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.
[0012] In accordance with a first preferred embodiment of the
present invention, a pump for use in handling one or more different
process fluids is provided which includes a plurality of pumping
chambers, where each pumping chamber includes at least one process
fluid inlet and at least one process fluid outlet. The process
fluid outlet on each pumping chamber is coupled to at least one
process fluid valve on each pumping chamber for selectively
preventing and allowing the flow of process fluid through the
pumping chamber. An actuation mechanism for pumping actuating fluid
to a plurality of actuating fluid chambers is provided that is in
fluid communication with the plurality of actuating fluid chambers
to permit flow into each actuating fluid chamber of substantially
incompressible actuating fluid. At least one diaphragm is provided
that separates each pumping chamber from an associated actuating
fluid chamber, for separating process fluid from actuating fluid.
Operation of the actuation mechanism to displace actuating fluid
causes actuating fluid to flow only into each of the plurality of
actuating fluid chambers having an opened process fluid valve,
resulting in pumping.
[0013] Unrestricted flow of actuating fluid from the actuating
fluid chamber into the actuation mechanism is preferably provided.
The actuation mechanism may be a piston translated by a screw
turned by a stepper motor. A controller may be provided for
selectively operating the at least one process fluid valve to which
each of the plurality of pumping chambers is coupled to selectively
allow and stop flow of process fluid. The at least one process
fluid valve may include a controllable valve for selectively
opening and closing a line coupled with the process fluid outlet.
Here, a one-way check valve coupled with the process fluid outlet
of each of the plurality of pumping chambers may be provided for
allowing fluid to flow only in one direction out of the pumping
chamber, and a one-way check valve coupled with the process fluid
inlet of each of the plurality of pumping chambers may be provided
for allowing fluid to flow only in one direction into the pumping
chamber. Each of the plurality of pumping chambers may be coupled
with a process fluid nozzle for dispensing process fluid. The
process fluid nozzles coupled to a plurality of pumping chambers
may be located and arranged on a processing line for dispensing
process fluids onto a semiconductor wafer. The process fluid outlet
of each of the plurality of pumping chambers may be in fluid
communication with a filter for filtering the process fluid. The
actuation mechanism may be mounted within a body, and each of the
plurality of pumping chambers may be at least partially formed by a
removable pump head structure supported on the body. A plurality of
pump head structures may be arrayed around the body. A flow path
between the process fluid inlet and the process fluid outlet on
each pumping chamber may be substantially uphill to facilitate
bubble removal.
[0014] In accordance with another preferred embodiment of the
present invention, a pump for use in handling one or more different
process fluids is provided. The pump includes an actuation
mechanism for pumping actuating fluid, a plurality of pumping
chambers and a like plurality of actuating fluid chambers, forming
a plurality of pairs of pumping chambers and actuating fluid
chambers, each pair having one of said pumping chambers adjacent
one of said actuating fluid chambers, and each pumping chamber
including at least one process fluid inlet and at least one process
fluid outlet. A diaphragm associated with each pair is provided,
located between the pumping chamber and actuating fluid chamber,
for separating process fluid from actuating fluid. Each actuating
fluid chamber is in fluid communication with the actuation
mechanism permitting flow into the actuating fluid chamber of
substantially incompressible actuating fluid. The process fluid
outlet on each pumping chamber is coupled to at least one process
fluid valve associated with each pumping chamber for selectively
preventing and allowing the flow of process fluid through the
pumping chamber. Operation of the actuation mechanism to displace
actuating fluid causes actuating fluid to flow only into each of
the plurality of actuating fluid chambers having an opened process
fluid valve, resulting in pumping.
[0015] Unrestricted flow of actuating fluid from the actuating
fluid chamber into the actuation mechanism may be provided. The
actuation mechanism may be comprised of a piston translated by a
screw turned by a stepper motor. The pump may further include a
controller for selectively operating the at least one process fluid
valve to which each of the plurality of pumping chambers is coupled
to selectively allow and stop flow of process fluid.
[0016] At least one process fluid valve may include a controllable
valve for selectively opening and closing a line coupled with the
process fluid outlet. Here, a one-way check valve coupled with the
process fluid outlet of each of the plurality of pumping chambers
may be provided for allowing fluid to flow only in one direction
out of the pumping chamber, and a one-way check valve coupled with
the process fluid inlet of each of the plurality of pumping
chambers may be provided for allowing fluid to flow only in one
direction into the pumping chamber. Each of the plurality of
pumping chambers may be coupled with a process fluid nozzle for
dispensing process fluid. Here, the process fluid nozzles coupled
to a plurality of pumping chambers may be located and arranged on a
processing line for dispensing process fluids onto a semiconductor
wafer.
[0017] The process fluid outlet of each of the plurality of pumping
chambers may be in fluid communication with a filter for filtering
the process fluid. The actuation mechanism may be mounted within a
body, and each of the plurality of pumping chambers may be at least
partially formed by a removable pump head structure supported on
the body. A plurality of pump head structures may be arrayed around
the body.
[0018] In another embodiment of the present invention, a pump for
use in concurrently handling one or more different process fluids
is provided which includes a central reservoir for storing
substantially incompressible actuating fluid, in which a
displacement member is disposed for moving actuating fluid into and
out of the reservoir, a plurality of pumping chambers surrounding
the central reservoir, each pumping chamber including at least one
process fluid inlet and at least one process fluid outlet, and a
plurality of actuating chambers for receiving actuating fluid from
the reservoir. Each of the plurality of pumping chambers includes a
diaphragm, the diaphragm separating each pumping chamber from an
adjacent one of the actuating chambers and separating actuating
fluid in the actuating chambers from process fluid in the pumping
chambers. At least one channel permits flow between the actuating
chamber and the reservoir of substantially incompressible actuating
fluid. At least one valve coupled with the at least one process
fluid outlet is coupled for preventing and allowing the flow of
process fluid through the pumping chamber. Operation of the
actuation mechanism to displace actuating fluid causes fluid to
flow only into pumping chambers with outlets coupled with at least
one valve that is opened.
[0019] For each pumping chamber, a one-way check valve coupled with
the process fluid outlet may be provided for allowing fluid to flow
only in one direction out of the pumping chamber, and a one-way
check valve coupled with the process fluid inlet of each of the
pumping chambers may be provided for allowing fluid to flow only in
one direction into the pumping chamber.
[0020] The pump may have a body having formed thereon a plurality
of faces where each face has mounted thereon one of the pump head
structures. Each face cooperates with one of a plurality of the
removable pump head structures. The adjacent actuating fluid
chambers may be located on the body. The diaphragm for each pumping
chamber may be mounted between respective ones of the plurality of
pump head structures and the actuating fluid chambers of the
body.
[0021] In another alternate embodiment of the present invention, a
pump for use in handling one or more different process fluids is
provided which includes an actuation mechanism for pumping
actuating fluid, a plurality of pumping chambers and a like
plurality of actuating fluid chambers, forming a plurality of
pairs, each pair having one of the pumping chambers adjacent one of
the actuating fluid chambers, and each pumping chamber including at
least one process fluid inlet and at least one process fluid
outlet. A diaphragm associated with each pair is provided, located
between the pumping chamber and actuating fluid chamber, for
separating process fluid from actuating fluid. Each actuating fluid
chamber is in fluid communication with the actuation mechanism to
provide for flow into each actuating fluid chamber of substantially
incompressible actuating fluid. The process fluid inlet on a first
one of the pumping chambers is in communication with a source of
process fluid, the process fluid outlet on the first one of the
pumping chambers in communication with the process fluid inlet on a
second one of the pumping chambers, and the process fluid outlet on
the second one of the pumping chambers is in fluid communication
with a dispense point. Each pumping chamber is coupled to at least
one process fluid valve on each pumping chamber for selectively
preventing and allowing the flow of process fluid through the
pumping chamber. Operation of the actuation mechanism to displace
actuating fluid causes actuating fluid to flow only into each of
the plurality of actuating fluid chambers having an opened process
fluid valve, resulting in pumping.
[0022] The process fluid outlet on the first one of the pumping
chambers may be in communication with an inlet of a fluid treatment
unit for treating process fluid, the process fluid inlet on a
second one of the pumping chambers may be in communication with an
outlet of the fluid treatment unit, and the process fluid outlet on
the second one of the pumping chamber may be in fluid communication
with a dispense point. The fluid treatment unit may be a
filter.
[0023] A valve between the actuating mechanism and the actuating
fluid chamber in the first one of the pumping chambers and a valve
between the actuating mechanism and an inlet of the actuating fluid
chamber in the second one of pumping chambers may be provided. A
valve between an outlet of the actuating fluid chamber in the first
one of the pumping chambers and the fluid treatment unit may be
provided. The actuation mechanism may be comprised of a piston
translated by a screw turned by a stepper motor. A controller for
selectively operating the at least one process fluid valve to which
each of the plurality of pumping chambers is coupled to selectively
allow and stop flow of process fluids may be provided. The at least
one process fluid valve may include a controllable valve for
selectively opening and closing a line coupled with the process
fluid outlet. A one-way check valve coupled with the process fluid
outlet of each of the plurality of pumping chambers may be provided
for allowing fluid to flow only in one direction out of the pumping
chamber, and a one-way check valve coupled with the process fluid
inlet of each of the plurality of pumping chambers may be provided
for allowing fluid to flow only in one direction into the pumping
chamber. Each of the plurality of pumping chambers may be coupled
with a process fluid nozzle for dispensing process fluid. The
process fluid nozzles coupled to a plurality of pumping chambers
may be located and arranged on a processing line for dispensing
process fluids onto a semiconductor wafer. The process fluid outlet
of each of the plurality of pumping chambers may be in fluid
communication with a filter for filtering the process fluid. The
process fluid inlet on a third one of the pumping chambers may be
in communication with a second source of process fluid, the process
fluid outlet on the third one of the pumping chambers may be in
communication with the process fluid inlet on a fourth one of the
pumping chambers, and the process fluid outlet on the fourth one of
the pumping chambers may be in fluid communication with a dispense
point.
[0024] The actuation mechanism may be mounted within a body, and
each of the plurality of pumping chambers may be at least partially
formed on the body. A plurality of pump head structures may be
provided that are arrayed around the body. The actuation mechanism
may be reversible and process fluid valve may be configurable to
achieve internal suck back. An external suck back valve may be
located adjacent to the dispense point.
[0025] In another embodiment of the present invention, for a pump
which includes an actuation mechanism for pumping actuating fluid,
a plurality of pumping chambers, and a plurality of actuating
chambers where each actuating chamber in fluid communication with
the actuation mechanism through at least one fluid communication
channel permitting flow of actuating fluid between the actuating
chamber and actuating mechanism, each of the plurality of pumping
chambers including at least one process fluid inlet and one process
fluid outlet, a method is provided. The method includes the steps
of charging each of the plurality of pumping chambers with process
fluid, activating the actuation mechanism in a first direction and
operating valves to cause a first of the plurality of pumping
chambers to fill with process fluid from a source, activating the
actuation mechanism in a second direction and operating valves to
cause the first of the plurality of pumping chambers to move
process fluid from the first of the plurality of pumping chambers
into a fluid treatment unit, activating the actuation mechanism in
a first direction and operating valves to cause a second of the
plurality of pumping chambers to fill with process fluid from the
fluid treatment unit, and activating the actuation mechanism in the
second direction and operating valves to cause the second of the
plurality of pumping chambers to move process fluid from the second
of the plurality of pumping chambers to a dispense point. The first
and second of the plurality of pumping chambers may operate at
different pressures.
[0026] In another embodiment of the method above, for a pump
comprised of an actuation mechanism for pumping actuating fluid, a
plurality of pumping chambers, and a plurality of actuating fluid
chambers, each actuating chamber in fluid communication with the
actuation mechanism through at least one fluid communication
channel permitting flow of actuating fluid between the actuating
chamber and actuating mechanism, each of the plurality of pumping
chambers including at least one process fluid inlet and one process
fluid outlet, a method is provided. The method includes the steps
of charging each of the plurality of pumping chambers with process
fluid, activating the actuation mechanism in a first direction and
operating valves to cause a first of the plurality of pumping
chambers to fill with process fluid from a source, selectively
opening for process fluid flow at least one outlet valve for at
least one of the plurality of pumping chambers, and closing the at
least one outlet valve for all remaining pumping chambers to create
back-pressure of process fluid in the pumping chambers to prevent
actuating fluid from flowing into associated actuating chambers.
Actuating fluid flows only into the pumping chambers having at
least one outlet valve opened, resulting in displacement of process
fluid from the associated pumping chamber. The first and second of
the plurality of pumping chambers may operate at different
pressures.
[0027] In another embodiment of the present invention, a pump for
use in handling one or more different process fluids is provided
that includes a plurality of pumping chambers, each pumping chamber
including at least one process fluid inlet and at least one process
fluid outlet, the at least one process fluid outlet on each pumping
chamber coupled to at least one process fluid valve on each pumping
chamber for selectively preventing and allowing the flow of process
fluid through the pumping chamber. The pump further includes an
actuation mechanism for pumping actuating fluid to a plurality of
actuating fluid chambers, the actuation mechanism in fluid
communication with the plurality of actuating fluid chambers to
permit flow into each actuating fluid chamber of substantially
incompressible actuating fluid. The pump further includes at least
one diaphragm separating each pumping chamber from an associated
actuating fluid chamber, for separating process fluid from
actuating fluid. The actuation mechanism is removable by a quick
disconnect connection that provides for disconnection of the
actuation mechanism without affecting process fluid in the process
fluid inlet, process fluid outlet, process fluid valve, or process
fluid in each pumping chamber. Operation of the actuation mechanism
to displace actuating fluid causes actuating fluid to flow only
into each of the plurality of actuating fluid chambers having an
opened process fluid valve, resulting in pumping.
[0028] A plurality of isolation valves may be used where each
isolation valve is located between the actuating mechanism and one
of the plurality of actuating fluid chambers for selectively
preventing and allowing the flow of process fluid between the
actuating mechanism and one or more selected actuating fluid
chambers. Each isolation valve may be a proportional control valve
to enable dispensing out of more than one pumping head
simultaneously, at at least one flow rate using a single one of the
actuating mechanism.
[0029] In another embodiment of the present invention, a pump for
use in handling one or more different process fluids is provided
that includes an actuation mechanism for pumping actuating fluid,
wherein the actuation mechanism is removable by a quick disconnect
connection that provides for disconnection of the activation
mechanism without affecting process fluid in the process fluid
inlet, process fluid outlet, process fluid valve, or process fluid
in each pumping chamber. Additionally provided are a plurality of
pumping chambers and a like plurality of actuating fluid chambers
forming a plurality of pairs of pumping chambers and actuating
fluid chambers, each pair having one of the pumping chambers
adjacent one of said actuating fluid chambers, each pumping chamber
including at least one process fluid inlet and at least one process
fluid outlet. Further provided are a diaphragm associated with each
pair, located between the pumping chamber and actuating fluid
chamber, for separating process fluid from actuating fluid, each
actuating fluid chamber in fluid communication with the actuation
mechanism permitting flow into the actuating fluid chamber of
substantially incompressible actuating fluid, and the at least one
process fluid outlet on each pumping chamber coupled to at least
one process fluid valve associated with each pumping chamber for
selectively preventing and allowing the flow of process fluid
through the pumping chamber. Operation of the actuation mechanism
to displace actuating fluid causes actuating fluid to flow only
into each of the plurality of actuating fluid chambers having an
opened process fluid valve, resulting in pumping.
[0030] A plurality of isolation valves may be provided where each
isolation valve is located between the actuating mechanism and one
of the plurality of actuating fluid chambers for selectively
preventing and allowing the flow of process fluid between the
actuating mechanism and one or more selected actuating fluid
chambers. Each isolation valve may be a proportional control valve
to enable dispensing out of more than one pumping head
simultaneously, at at least one flow rate using a single one of the
actuating mechanism.
[0031] In another embodiment of the present invention, a pump for
use in handling one or more different process fluids is provided
that includes an actuation mechanism for pumping actuating fluid,
wherein the actuation mechanism is removable by a quick disconnect
connection that provides for disconnection of the actuation
mechanism without affecting process fluid in the process fluid
inlet, process fluid outlet, process fluid valve, or process fluid
in each pumping chamber. Further included are a plurality of
pumping chambers and a like plurality of actuating fluid chambers,
forming a plurality of pairs, each pair having one of the pumping
chambers adjacent one of the actuating fluid chambers, each pumping
chamber including at least one process fluid inlet and at least one
process fluid outlet. Further included are a diaphragm associated
with each pair, located between the pumping chamber and actuating
fluid chamber, for separating process fluid from actuating fluid,
each actuating fluid chamber in fluid communication with the
actuation mechanism to provide for flow into each actuating fluid
chamber of substantially incompressible actuating fluid, the
process fluid inlet on a first one of the pumping chambers in
communication with a source of process fluid, the process fluid
outlet on the first one of the pumping chambers in communication
with the process fluid inlet on a second one of the pumping
chambers, the process fluid outlet on the second one of the pumping
chambers in fluid communication with a dispense point, each pumping
chamber coupled to at least one process fluid valve on each pumping
chamber for selectively preventing and allowing the flow of process
fluid through the pumping chamber. Operation of the actuation
mechanism to displace actuating fluid causes actuating fluid to
flow only into each of the plurality of actuating fluid chambers
having an opened process fluid valve, resulting in pumping.
[0032] A plurality of isolation valves may be provided where each
isolation valve is located between the actuating mechanism and one
of the plurality of actuating fluid chambers for selectively
preventing and allowing the flow of process fluid between the
actuating mechanism and one or more selected actuating fluid
chambers. Each isolation valve may be a proportional control valve
to enable dispensing out of more than one pumping head
simultaneously, at at least one flow rate using a single one of the
actuating mechanism.
[0033] Finally, a pump for use in handling one or more different
process fluids is provided that includes a plurality of pumping
chambers, each pumping chamber including at least one process fluid
inlet and at least one process fluid outlet, the at least one
process fluid outlet on each pumping chamber coupled to at least
one process fluid valve on each pumping chamber for selectively
preventing and allowing the flow of process fluid through the
pumping chamber, at least one an actuation mechanism to apply a
force to each of the pumping chambers to cause process fluid
through each of the pumping chamber, resulting in pumping, and a
plurality of isolation valves, each isolation valve for selectively
preventing and allowing the flow of process fluid. Each isolation
valve may be a proportional control valve to enable dispensing out
of more than one pumping head simultaneously, at at least one flow
rate using a single one of the actuating mechanism.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS
[0034] FIG. 1 is a schematic view of a single stage, multiple head
pump, shown in the context of a high precision, high-purity fluid
dispensing system in accordance with a first preferred embodiment
of the present invention.
[0035] FIG. 2 is an exploded isometric view of the multiple head
pump of FIG. 1.
[0036] FIG. 3 is an exploded view of the multiple head pump of FIG.
1, shown from a different angle of the multiple head pump of FIG.
2.
[0037] FIG. 4 is a side, elevation view of the pump of FIGS. 2 and
3, assembled.
[0038] FIG. 5 is a cross-sectional of the pump of FIG. 4, taken
along section line 5-5 of FIG. 4.
[0039] FIG. 6 is a cross-sectional view of the pump of FIG. 4 taken
along section line 6-6 of FIG. 4.
[0040] FIG. 7 is an isometric view of the pump of FIG. 4.
[0041] FIG. 8 is a front elevation view of the pump of FIG. 4.
[0042] FIG. 9 is a rear elevation view of the pump of FIG. 4.
[0043] FIG. 10 is a simplified, isometric view of an application of
the pump of FIGS. 2-9.
[0044] FIG. 10A is a partial isometric view of an alternate
embodiment of the pump application shown in FIG. 10, but having
three dispense valves dispensing fluid to three different
semiconductor wafers.
[0045] FIGS. 11A, 11B and 11C constitute a flow chart of an
exemplary dispense process of a controller for the pump of FIGS.
2-9.
[0046] FIG. 12 is a schematic diagram of a two-stage pumping system
utilizing a multi-head pump in accordance with a second preferred
embodiment of the present invention.
[0047] FIG. 13 is a schematic diagram of an alternate two-stage
pumping system utilizing a multi-head pump in accordance with a
third preferred embodiment of the present invention.
[0048] FIG. 14 is a schematic diagram of another alternate
embodiment of a two-stage pumping system utilizing a multi-head
pump in accordance with a fourth preferred embodiment of the
present invention.
[0049] FIG. 15 is a schematic diagram of an example of a two-stage
pumping system utilizing two or more multi-head pumps in accordance
with a fifth preferred embodiment of the present invention.
[0050] FIG. 16 is a schematic view of a single stage, multiple head
pump, shown having internal suck back utilizing an input
check-valve and an output valve.
[0051] FIG. 17 is a schematic view of a single stage, multiple head
pump, shown having internal suck back utilizing an input valve and
an output valve.
[0052] FIG. 18 is a schematic view of a single stage, multiple head
pump, shown having external suck back utilizing input and output
check-valves.
[0053] FIG. 18A is a schematic view of a single stage, multiple
head pump, shown having external suck back utilizing input and
output check-valves and a set of isolation valves.
[0054] FIG. 19 is a schematic view of a single stage, multiple head
pump, shown having external suck back utilizing input and output
valves.
[0055] FIG. 20 is a simplified, isometric view of an alternate
application of the pump of that splits its output to supply fluid
to three separate outputs.
[0056] FIG. 21 is simplified, isometric view of the alternate
embodiment of FIG. 20, shown with the addition of a filtering
unit.
[0057] FIG. 22 is a rear elevation view of a pump having isolation
valves in accordance with another alternate embodiment of a pump in
accordance with the present invention.
[0058] FIG. 23 is a side elevation view of the pump of FIG. 22.
[0059] FIG. 24 is a partial exploded isometric view of the pump of
FIG. 22.
[0060] FIG. 25 is another partial exploded isometric view of the
pump of FIG. 22.
[0061] FIG. 26 is partial top view of the pump of FIG. 22.
[0062] FIG. 27 is partial view of the pump of FIG. 26 depicting
detail A.
DETAILED DESCRIPTION OF INVENTION
[0063] FIG. 1 schematically illustrates one example of a high
precision, single stage, 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 actuation mechanism. In the
illustrated example, a multiple head pump is used to dispense
chemicals or process fluids from three separate 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 source can 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 113, 115 or 117
to their corresponding dispense points 107, 109, 111. 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 valves 119, 121, 123 in the illustrated example are coupled
to suck back valves 125, 127 and 129. After a dispense, a suck back
valve 125, 127, 129 is used to draw fluid back from a dispense
point 107, 109, 111 nozzle, or similar element in order to prevent
dripping.
[0064] In the illustrated example, the pump heads move process
fluid by drawing it into a pumping chamber (integral to the pump
head) and then displacing the process fluid. 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. The instant
example contemplates use of flexible diaphragm as a displacement
member that cooperates with the walls of the pumping chamber.
Moving the diaphragm in one direction increases the volume of the
pumping chamber, and moving the diaphragm in another direction
decreases the volume of the pumping chamber. The diaphragms for
pump heads 113, 115 and 117 are schematically illustrated in the
figure as elements 131, 133 and 135, respectively.
[0065] A number of different arrangements can be used to ensure
that fluid flows only in one direction through the pump head 113,
115, 117. In the illustrated example, the pump heads 113, 115, 117
include inlets (not indicated) for coupling the pump heads to the
process fluid sources, such as sources 101, 103 or 105, and outlets
(not indicated) for coupling the pump heads 113, 115, 117 to
dispense points, such as dispense points 107, 109 or 111. The
pumping chamber in each 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
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
during normal operation, that fluid flows into the pumping chamber
only from the inlet and exists the pumping chamber only through the
outlet.
[0066] 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, 137A, 137B ensures
one-way flow from the inlet into the pumping chamber, and check
valve 139, 139A, 139B 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 113, 115, 117. 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.
[0067] Each of the pump heads 113, 115, 117 shares a common
actuation mechanism 136, represented in the figure by drive motor
and piston assembly. An actuation 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 actuation
mechanisms 136 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 first 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.
[0068] In the illustrated example, the force generated by the
common actuation mechanism 136 is preferably applied in parallel,
rather than serially, to each of the pump heads 113, 115, 117.
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.
[0069] In order to avoid undesirable, simultaneous actuation of all
pump heads 113, 115, 117, yet maintain simplicity, the actuation
mechanism 136 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 136 in the illustrated example includes
a drive (stepper) 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 pump 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 pump 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.
[0070] Blocking flow of process fluid out of the pumping chamber of
a pump head 113, 115, 117 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 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 be used also for this
purpose.
[0071] Optionally, when used for metering fluids, the pump is
operated so that only one pump head 113, 115, 117 is active at a
time. All actuating fluid is thereby directed only into or out of
the active pump head. By allowing actuating fluid to flow only out
of one pump head at a time, the amount of process fluid being
pumped may be 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 of process fluid 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.
[0072] Referring now to FIGS. 2 through 9, an exemplary
single-stage pump 200 is shown 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. In this example, the pumping head structures
202, 204, 206 are arrayed around a central body 208. In other
preferred embodiments, the pumping head structures 202, 204, 206
need not be arrayed around the central body 208. The central body
208 supports the pumping head structures 202, 204, 206 and
preferably also provides channels in the form of holes or
passageways through the central body 208 for supplying 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 actuating fluid. In high purity applications such
as semiconductor fabrication, even the smallest leak may
contaminate the clean environment and is therefore very
undesirable.
[0073] The central body 208 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 head structures 202, 204, 206
are coupled. The fourth side is used, in this example, to receive a
pressure sensor 210. The pressure sensor 210 is used to measure the
pressure of actuating fluid within the actuation mechanism.
Arraying the pumping head structures 202, 204, 206 at least
partially around channels supplying actuating 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 advantages of the exemplary pump
illustrated in these figures can be achieved without the pumping
heads being arrayed around the central body 208. For example, the
pumping head structures can be arranged in a stacked configuration.
More pumping head structures can be coupled to the central body 208
by increasing the cross-sectional size, increasing the number of
faces disposed around the central body 208, by reducing the size of
the pumping head structures 202, 204, 206, and/or by extending the
body 208 along its central axis. The size of the pumping head
structures 202, 204, 206 depends in part on the desired volume of
the pumping chamber within each pumping head structure. 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 208
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 structures 202, 204, 206.
[0074] The central body 208 preferably also houses, as in this
example, at least one actuation mechanism, for example, a hydraulic
actuation mechanism. The actuation mechanism includes an actuating
fluid reservoir as well as a displacement element. In the
illustrated embodiment, the actuating 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 actuation mechanism in the central body 209 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 coupled, for example,
hydraulically, with the pumping head structures 202, 204, 206, 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 208 is extended by
joining multiple blocks, the actuation mechanism could be located
in one of the blocks and hydraulically coupled with the other block
through a passageway or external line.
[0075] 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.
[0076] In each of the pumping head structures 202, 204, 206,
diaphragm 212 extends across the face portion 211 and cooperates
with a pumping head structure 202, 204, 206 to define a pumping
chamber 214 (see FIG. 5) on one side of the diaphragm 212, and with
a depression 216 (see FIG. 5) formed in the body 208, at the face
portion 211, to define an actuating fluid chamber 218 (see FIG. 5)
on the opposite side of the diaphragm 212. In this preferred
embodiment of the exemplary pump 200, the diaphragm 212 can be
easily removed and replaced by removing the pumping head assembly
202, 204 or 206. The diaphragm 212 is sealed against the
cooperating face portion 211 of body 208 by O-ring seal 220. Plate
222 attaches the diaphragm 212 to the face portion 211 of the body
208. Among other advantages, attaching the diaphragm 212 with the
plate 222 allows the pump 200 to be built and charged with
actuating fluid--preferably a substantially incompressible fluid
(at least at the pressures typically encountered in the
application), such as glycol--prior to the pump head structures
202, 204, 206 being assembled with the body 208. The diaphragms 212
are preferably made from a translucent material in order to permit
visual identification of any air or gas bubbles within the
actuating fluid prior to attaching the pumping head structures 202,
204, 206. Although one diaphragm 212 per pumping head structure
202, 204, 206 is being used in the illustrated embodiment, two or
more adjacent pumping head structures 202, 204, 206 could instead
use a different area of one, larger diaphragm 212, isolated by a
seal or other structure, so that process fluid does not leak
between the pump head structures 202, 204, 206. As seen in FIGS. 2
and 5, vent line 223 permits air to be purged from the actuating
fluid chamber 218. Vent lines 223 are sealed with plugs that are
not shown in the figures. Air entrapped in the actuating fluid
and/or process fluid, pumping chamber, actuating fluid chamber 218,
cavity 207 or any of the channels within the pump carrying the
fluids, can also be detected by charging the pumping chambers 214
with process fluid, closing each of them so that process fluid
cannot flow out, pumping the actuating fluid and monitoring the
pressure of the actuating 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.
[0077] Each pumping head structure 202, 204 and 206 is an assembly
that includes a pumping chamber cover 224 with a cavity or
depression 226. The cover 224 cooperates with the diaphragm 212 to
form pumping chamber 214. O-ring 225 forms a seal between the cover
224 and diaphragm 212. 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 214. The inlet
orifice 228 is located near the bottom of the pumping chamber 214
so that fluid flows upward, against gravity, when the pump 200 is
in a normal operating position, toward the outlet orifice 230. This
arrangement and the elongated form of the pumping chamber 214 tends
to reduce pooling of process fluid within the pumping chamber 214
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 chamber 214 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.
[0078] Each pumping head structure 202, 204, 206 includes
connectors for connecting lines carrying process fluid into and out
of the pumping head structure 202, 204, 206. 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
214 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 232, 234 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.RTM. and
Super 300 Type Pillar Fitting.RTM. of Nippon Packing Co., Ltd.,
Flowell.RTM. flare fittings, Flaretek.RTM. fittings from Entegris,
"Parflare" tube fittings from Parker, LQ, LQ1, LQ2 and LQ3 fittings
from SMC Corporation, Furon.RTM. Flare Grip.RTM. fittings and
Furon.RTM. 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 pumping head
assembly 202, 204, 206. However, the assembly could be fabricated
using fewer or more components.
[0079] The connector block 236 includes a passageway that carries
fluid from the inlet fitting 232 into the connector block 236
toward the inlet orifice 228 of the pumping chamber 214. In this
example, the passageway is formed by a channel 238 formed on the
surface of block 236 and a cooperating gasket 240. The gasket 240
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.
[0080] in the illustrated example (see FIG. 3), a one-way check
valve 246 is integrated into the connector block 236 that allows
fluid to flow only from the inlet fitting 232 to the pumping
chamber 214. The check valve 246 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 250 to the orifice plate
248. Fluid flowing under pressure through the holes in the orifice
plate 248, toward the valve 250, tends to cause the edges of the
valve 250 to curl up or lift, while the center of the valve 250
remains stationary. The valve 250 has an inverted shape. When it is
assembled, the stem pulls the edges of the valve 250 against the
orifice plate 248, thereby creating a seating force that presses
the perimeter of the valve 250 against the plate 248. 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.
[0081] The connector block 236 also includes a passageway that
carries fluid exiting pumping chamber 214 to the outlet fitting
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 (see FIG. 2) formed on
the back of pumping chamber cover 224. Umbrella-shaped valve 256 is
attached to the orifice plate 254. Fluid is 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. The 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
bore into which outlet 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 252 and flow of
fluid from around the edges of the valve 252 without restricting
the flow.
[0082] As seen in FIG. 5, incompressible actuating fluid is stored
in the central chamber or cavity 207 of the actuation mechanism.
When displacement element 209 (piston) translates within the cavity
207, passageways 263 communicate fluid between the cavity 207 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 pumping head structure 202, 204, 206 when the
piston is retracted, causing the actuating fluid to be drawn into
the cavity 207.
[0083] 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
212 is permitted to move. 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 212 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 214 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 214 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 diaphragm
212 can be moved to displace the process fluid in the pumping
chamber 214, which, in turn, determines whether actuating fluid
flows into the actuating fluid chamber 218 for the given pumping
head structure 202, 204, 206. By opening the outlet valve of only
one pumping head structure, 202, 204, 206, all the actuating fluid
caused by displacement of displacement element 209 (piston) will be
forced to flow into only the actuating fluid chamber 218 of the
pumping head structure 202, 204, 206 with the open outlet valve.
The volume of actuating fluid displaced by movement of displacement
element 209 (piston) will equal the volume of process fluid
displaced by the diaphragm 212 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.
[0084] As process fluid is always permitted to flow in to each of
the pumping chambers 214 in the illustrated embodiment, actuating
fluid will always flow from each actuating fluid chamber 218 during
retraction of displacement element 209 (piston), at least until the
diaphragm 212 reaches its full capacity. The wall forming
depression 216 preferably includes a channel 217 to ensure that the
diaphragm 212 has sufficient fluid behind it and allow flow,
preventing the diaphragm from sticking to the wall. Thus, the
illustrated embodiment of pump 200 will simultaneously recharge, or
recharge in parallel, each pumping chamber in the pump, regarding
less of the number of pumping head structures 202, 204, 206.
[0085] Displacement element 209 (piston) includes 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
264. Thrust bearing 272 prevents the drive screw 266 from axially
loading the output shaft 270 of the motor. The threads on the drive
screw 266 couple with threads on the inside of the displacement
element 209 (piston). The angular position of the piston is fixed
by a guide 274, which is clamped to the piston (displacement
element 209) and cooperates with slot 276 (see FIG. 3) to prevent
rotation of the piston. Turning the drive screw 266 moves the
piston. Other types of mechanisms for translating the piston could,
however, be substituted. An optical sensor 278 (see FIG. 3) detects
when guide 274, and thus piston (displacement element 209), is at a
predetermined limit during upstroke. This is used to calibrate the
pump 200. Cover 280 seals an opening that allows access to the
cavity 207 for assembly and cleaning.
[0086] 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.RTM..
[0087] 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 container 302. The respective
containers are numbered 302a, 302b and 302c. Each container
supplies process fluid to one of the pumping head structures 202,
204 or 206. In this example, container 302a supplies pumping head
structure 204 through supply line 304a; container 302b supplies
pumping head structure 202 through supply line 304b; and container
302c supplies pumping head structure 206 through supply line 304c.
Each of the supply lines is connected to the inlet fitting 232 (see
FIG. 2) of the pumping head structure that it supplies with process
fluid.
[0088] The outlet fitting 234 (see FIG. 2) of each of the pumping
head structures 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. Of course, not all three filters are required.
Filtering (or otherwise treating) the process fluid is optional.
Furthermore, less 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. As best seen in FIG. 10, the outlet of each of dispense
valves is connected to a respective nozzle, from which process
fluid is dispensed onto wafer 300. Not all of the pumping head
structures on pump 200 need to be used to service one wafer
300.
[0089] The pumping head structures 200, 202, 204 may also be used,
for example, to supply process fluid to more than one wafer 300A,
300B, 300C, as shown in FIG. 10A.
[0090] Operation of the pump 200 and dispense valves 312 are
controlled by a controller 314. Preferably, the controller 314 is
programmable and 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
200. The controller 314 typically receives a demand for dispense
signal from a manufacturing line, where the wafer 300 is being
processed. However, the control processes can be implemented in the
line controller or other processing entity associated with the
fabrication facility.
[0091] 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 FIGS. 10
and 10A. The process takes place within the controller 314 when the
controller is in a dispense mode. In this example, the controller
314 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 pumping head structures 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
logically or virtually. For example, the controller 314 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.
[0092] Starting with step 400 in FIG. 11A, 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.
[0093] 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.
[0094] 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 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.
[0095] 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 acknowledges the end of
dispense.
[0096] 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 pump is now
full and ready to dispense again and a "Ready Signal is Sent" in
step 496. 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.
[0097] Referring now to FIGS. 12, 13, 14 and 15, other multi-headed
pumps, such as the ones discussed above in connection with FIGS.
1-11 are shown in two-stage pumping systems. Four examples 500,
502, 504 and 505 of the two-stage pumping systems are illustrated,
respectively, in FIGS. 12, 13, 14 and 15. Example 505 of FIG. 15
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. For convenience
sake, the various elements of the second pump are designated with
an "A" suffix in the figure to assist in distinguishing the first
pump from the second pump. For example, the pumping chambers 506,
508 of the first pump are pumping chambers 506A, 508A of the second
pump. Each of the remaining examples is of just a two-stage pumping
system, with both stages sharing the same actuation mechanism.
[0098] In each of the examples of a two-stage pumping system, a
pumping chamber 506 is used as a first stage, and a 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 be used to drive the
same stage of more than two, two-stage pumps, if desired.
[0099] The first stage of the pump is used to pull fluid from a
source 509 and push it to a fluid treatment unit, such as a filter,
generally designated by filter 510. The second stage is used for
moving 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 a valve 514, and a drain, controlled in these examples
by a 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 type 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.
[0100] 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.
[0101] In all examples 500, 502, 504 and 505, multiple pumping
chambers are driven by a single actuation 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
actuation mechanism (stepper motor 526, screw 528, piston within
cylinder 530) 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 actuation
mechanism (stepper motor 526, screw 528, piston within cylinder
530), and the second stage pumping chambers 508 are driven by a
second, common actuation mechanism.
[0102] 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.RTM.. Other examples
include high density polyethylene and polypropylene and PFA
(perfluoroalkoxy copolymer resin).
[0103] The actuation mechanism (stepper motor 526, screw 528,
piston within cylinder 530) operates substantially similarly to the
actuation mechanism described in connection with FIGS. 1-9.
Actuation of an actuation mechanism causes actuating fluid to flow
through fluid conduits extending between actuation 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
actuating fluid, and combinations of the foregoing. Surfaces
contacting the actuating fluid do not need to be of a type for
maintaining high purity, such as those required for the process
fluid.
[0104] In two-stage pumping systems 500, 502 and 505, shown in
FIGS. 12, 13 and 15, respectively, the actuation mechanisms
(stepper motor 526, screw 528, piston within cylinder 530) are
coupled to pumping chambers through valves 532 and 534. Valves 532
and 534 are used to control the flow of actuating fluid between the
actuation 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 actuating 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, the valves 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.
[0105] 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 actuation
mechanism.
[0106] Referring now only to FIGS. 12 and 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. Actuating fluid valve 534 for
the second stage is also opened. Drive motor 526 turns drive screw
528, moving the piston in cylinder 530. The piston advances
forward, pushing actuating fluid out of the cylinder 530. Blocked
by closed first stage actuating fluid valve 532, the actuating
fluid moves through valve 534 and into pumping chamber 508, causing
movement of a process displacement member, such as some type of
diaphragm. As the actuating fluid moves in, it displaces an equal
volume of process fluid. The process fluid exits the chamber 508.
It is blocked by check valve 522, so it flows through output valve
518 and out a dispense tip onto the wafer 512. 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
actuating fluid back into the cylinder 530. This pulls the process
fluid displacement member (diaphragm), 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 and 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. Actuating
fluid valve 532 is opened and the motor 526 is actuated to cause
actuating 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.
[0107] 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.
[0108] The two-stage pumping system of FIG. 14 functions similarly
to the system shown in FIGS. 12 and 13. However, valve 532 is
replaced by valve 536, and, 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,
actuating 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, actuating 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.
[0109] 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 of the actuation mechanisms (stepper motor
526, 526A, screw 528, 528A, piston within cylinder 530, 530A)
drives only one of the two stages and therefore, they must be
operated in a coordinated fashion. Once the actuation 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. 12-13. Similarly, the
second actuation mechanism selectively actuates either of the
pumping chambers 508 in the manner described. This arrangement,
thus, confers the benefits of having fewer actuation 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 actuation mechanism, if desired.
[0110] Valves 532 and 534 are optional for each of the actuation
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 operated independently of the
second stage of each of the two pumping systems. However, if the
reservoirs or filters of the respective two-stage pumping systems
505 need to be filled independently, then an output valve, like
valve 536, would be desirable to have.
[0111] The present invention can be configured for either internal
or external suck back. For purposes of the present invention,
"internal suck back" refers to draw back of fluid into the dispense
tip after the completion of a dispense cycle. This is accomplished
internal to the pump by reversing the actuation mechanism (e.g.,
stepper motor 526, screw 528, piston within cylinder 530). The term
"external suck back" uses an external valve and control, typically
placed as close to the dispense tip as possible. Both methods
provide advantages and disadvantages, as described below.
[0112] Referring now to FIGS. 16 and 17, a pump having internal
suck back 600 will now be described. In the internal suck back pump
shown schematically in FIG. 16, an input check valve 602 and an
output valve 604 are shown. The internal suck back pump 600A of
FIG. 17 shows a system having an input valve 606 (rather than the
check valve 602 of FIG. 16) and output valve 604. The pumps of
FIGS. 16 and 17 operate with about the same effectiveness.
[0113] It is noted that, while the pumps shown in the various
figures herein throughout this specification depict either all
internal suck back pumps or all external suck back pumps, a mix of
internal and external suck back pumps would operate
effectively.
[0114] As shown in FIGS. 16 and 17, actuation mechanisms 608 are
shown. The actuation mechanisms 608 may be similar to that
previously described with respect to the prior embodiments and may
include, for example, stepper motor, screw and piston within
cylinder. The details will not be repeated here. The stepper motor
of the actuation mechanism 608 drives the drive screw. The drive
screw moves piston that is caused to reciprocate by the threads on
the drive screw. As the drive screw is turned, the threads of the
drive screw retract the piston, forcing the piston to be pulled
slightly within its cylinder, thereby moving a diaphragm 610. The
expanding volume in the pumping chamber draws fluid into the
pumping chamber from the source 612. The fluid passes through the
input check valve 602 (FIG. 16) or, optionally, the two-way valve
606 (FIG. 17) and into the pumping chamber. When the pumping
chamber is full of fluid, all valves close and the unit comes to
rest in its "ready" state.
[0115] When a dispense is called for, the selected output valve 604
is opened, and the stepper motor of the actuation mechanism 608
turns in the opposite direction, causing the piston to be driven in
a displacement direction, reducing the volume of process fluid in
the pumping chamber. This forces fluid out of the pumping chamber
and through the output valve, then out of the dispense tip 614. The
timing of the opening of the output valve 604 is controlled to give
the desired process results. The output valve 604 can be opened
slightly before the stepper motor of the actuation mechanism 608
starts to start dispensing, or it can be delayed to open at a
desired point after the stepper motor starts operating. This allows
the pump to build up pressure for different dispense
characteristics.
[0116] Once the desired required volume of fluid is dispensed, and
if internal suck back is required, the pump waits a desired delay
time, if selected, then the stepper motor direction is reversed.
The output valve 604 remains opened and the input valve 606 is kept
closed (or, if a check valve 602 is used, as shown in FIG. 16, the
suck back is done in such a way to keep the draw pressure below the
cracking pressure of the check valve 602). As the stepper motor is
stepped in the recharge direction, the fluid is drawn back up the
dispense tip 614 to a desired point, or drawn back to a given
volume in the cylinder or pumping chamber. Pulling the fluid back
helps prevent the fluid from dripping and drying, causing
contamination on the newly processed wafer below the dispense tip
614.
[0117] It is noted that if a pump the type shown in FIG. 5 is used,
umbrella-shaped valve 256 must be removed or replaced with a
two-way valve for proper operation if internal suck back is
used.
[0118] Next, a pump 700, 700A (see FIGS. 18 and 19) having external
suck back will be described. External suck back is sometimes also
called "remote suck back" and is used interchangeably. External
suck back can be accomplished with check valves 702, 704, as shown
in the pump 700 of FIG. 18 or as shown in the pump 700A of FIG. 19
with two valves, input valve 706 and output valve 708. As seen in
FIGS. 18 and 19, suck back and its control is accomplished external
to the single stage pump (e.g., as shown in FIGS. 2-10 as reference
number 200). However, the same result is achieved as with internal
suck back, as described with respect to FIGS. 16 and 17. A motor or
other mechanism (such as an air actuator) moves a suck back piston
in a remote housing.
[0119] FIG. 18A is similar to the pumps 700, 700A of FIGS. 18 and
19. FIG. 18A depicts a pump 900 having external suck back using
similar check valves, input valves, output valves, and the like.
However, the pump 900 includes the addition of three isolation
valves 902, 904, 906. The three isolation valves 902, 904, 906
allow the diaphragms 908, 910, 912 and pump heads 914, 916, 918 to
never see the pressure used by one another. For example, if all
three isolation valves 902, 904, 905 are open and a dispense is
made using pump head 914 at dispense tip 920 at 10 PSI. Output
valve 926 is open, while output valves 928 and 930 are closed. No
dispense is intended to be made using pump heads 916, 918 through
dispense tips 922, 924. This 10 PSI pressure would be transmitted
to the other two unused pump heads 916, 918 down to the closed
output valves 928, 930 as well. The pressure in the whole system
would go to 10 PSI. This includes the areas of the tubing between
the unused output check valves 934, 936 and the output valves 928,
930. Of course, process fluid flows through the output check valve
932 currently in use. When the dispense through dispense tip 920 is
complete, the 10 PSI pressure at the unused output check valves
934, 936 through to the output valves 928, 930 is maintained. Now,
the example continues with a desired 3 PSI dispense from dispense
point 922. Since there is a residual pressure of 10 PSI, as
explained above, when output valve 928 is opened, a small blast of
fluid at 10 PSI will first be made, then the pressure will drop
down to the required 3 PSI. The use of the isolation valves 902,
904, 906, operated at appropriate intervals by a controller, is
used to prevent this "crosstalk" in the channels, if needed.
Specifically, prior to driving drive mechanism 938, the unused
isolation valves (in the present example, isolation valves 904,
906) are closed. Actuating fluid therefore does not act on the
unused pump heads (in the present example, pump heads 916, 918).
Therefore the undesirable pressure, described above, is effectively
eliminated.
[0120] The use of isolation valves 902, 904, 906 may also be used
to selectively isolate at least one pump 914, 916, 918 at a time
for dispensing. It is possible to simultaneously dispense out of
more than one pump chamber at the time, even at different
rates.
[0121] This is shown in more detail in the embodiment of FIGS.
22-25. Appropriate isolation valves 1004 may be, for example, LEE
company, part number LHDA1260245D. However, any other very small
valves such as cartridge valves could be used with different
mounting configurations and different tolerances to various
chemicals that are used as actuating fluids in the pump. Any
appropriate two-way valve could be used.
[0122] The isolation valves 1004 are mounted into a cartridge valve
subassembly 1002. There is at least one isolation valve 1004 for
each pumping head 204' so that at least one isolation valve 1004
can be open during the dispense to selectively direct actuation
fluid.
[0123] If the dispense is being executed out of a single pump head
204', then the isolation valve 1004 that corresponds to that pump
head 204' is opened to selectively allow actuating fluid to flow
into the actuating fluid chamber of pump head 204', thus affecting
the pumping action for the process fluid.
[0124] It is possible to dispense out of more than one pumping head
204' at a time, even at different flow rates, while using the
single actuating mechanism 136' (see FIG. 25). This is accomplished
by using proportional control valves for the actuating fluid
isolation valves, instead of the simple on/off valves 1004, such as
cartridge valves. Preferably, the proportional control valves are
installed in the same place as the standard on-off isolation
valves, however, they would have proportional control
functionality.
[0125] In pump's 200' control software, this is accomplished by
setting the pump drive system flow rate equal to the sum of the
individual flow rates required for each pump head involved in that
particular pumping operation at that point of time in the dispense.
Therefore, for each instance of time during the dispense, the total
flow rate is equal to the sum of the individual flow rates required
at each pump head. As a mathematical equation this would be
represented with:
Q rate pumptotal=Q rate 1+Q rate 2+ . . . +Q rate n
[0126] In the pump control software, this value is constantly
updated during the dispense and depends upon how the flow rates
vary among the various dispense pumping heads involved in that
particular dispense. The flow is divided by individually setting
the proportional control for the isolation valves associated with
the pump chambers. The setting for each isolation valve is
determined according to the proportion of the flow that needs to be
going out of the corresponding pump head at any given moment during
the dispense. Therefore, for each instance of time during the
dispense, the proportional control of the valves will be set
according to the following mathematical equations:
valve 1 setting=Q rate 1/Q rate pumptotal
valve 2 setting=Q rate 2/Q rate pumptotal
valve n setting=Q rate n/Q rate pumptotal
[0127] A typical software update/refresh rate for this type of
control system application might be 250 ms. Therefore, every 250 ms
the control software will check to see what the flow rate is
supposed to be out of each of the pump chambers that is currently
in use. The control software will then set the pump total flow rate
and the valves proportional control settings accordingly (based on
the above described equations).
[0128] It is important to note that this algorithm could be used in
any pumping situation where a single drive system is used to pump
out of multiple pump heads at the same time. It is not limited to
the semiconductor industry, or any particular industry or
application for that matter.
[0129] Finally, the figures and description above refer to the
different pumping head structures (e.g., 202, 204, 206, FIG. 7)
each pumping a different chemistry onto a single wafer. This setup
provides for use of a single pump to pick the desired chemistry.
Another option, as shown in the pumps 800, 800A of FIGS. 20 and 21
is to use a single source 802 having a single chemistry and utilize
a pump assembly 804 (for example, that shown in U.S. Pat. No.
4,950,124, the complete reference being fully incorporated by
reference herein) having to supply the chemistry to different
nozzles 806A, 806B, 806C for different wafers 808A, 808B, 808C.
FIGS. 20 and 21 both show pumps 800, 800A and are essentially the
same except that FIG. 21 adds filters 810A between the pump
assembly 804 and manifold 812. The pumps assemblies 800, 800A shown
in FIGS. 20 and 21 use a single source and single chemistry and
split the output to multiple dispense points (nozzles 806A, 806B,
806C). It is noted that the pump assemblies here do not require
multiple pumping head structures, as in the previous
embodiments.
[0130] An advantage of this configuration is in the filtering. The
filters are relatively expensive and must be changed regularly.
However, in spite of the cost of the filters, the price of a defect
in production is typically much more. Filters are therefore changed
at a time prior to a time when they cause problems due to filter
loading. Here, the filter is changed at one time for all dispense
points associated with the pump.
[0131] Finally, splitting the output as shown in FIGS. 20 and 21 is
not necessarily limited to the type of pump shown. The output of
any pump may be split in this manner, including that of two stage
pumps.
[0132] As stated above, one highly desirable feature of a precision
pump in accordance with the present invention is the ability to
separate and remove components of the pump 200' for maintenance or
repair without breaking into the process fluid flow lines that are
attached to one or more pump chamber heads. This would include
avoiding opening of any seals in the process fluid flowpath either
into, through, or out of the pump.
[0133] As can best be seen in FIGS. 25-27, the pump 200' is
designed such that the actuation mechanism 136' (including motor
264, drive screw (see FIG. 5 reference number 266), displacement
element (see FIG. 5, reference number 209), cavity (see FIG. 5,
reference number 207) and related components described above with
respect to FIG. 5) is easy to separate from the central body 208'.
The screws to attach the actuating mechanism 136' to the pump body
208' are easily accessible from the top of the pump 200'. Since the
actuating mechanism 136' is the part of the pump that is most
likely to need regular maintenance or repair, it is very useful to
be able to remove the actuating mechanism 136' from the pump 200'
without breaking into process lines that are attached into and out
of each of the pumping chambers (214, as shown in FIG. 5) of the
pumping head structures 202', 204', 205', 206'.
[0134] The motor 264, drive screw 266 and displacement element 209
of the pump are the most likely components to experience mechanical
wear and failure. Therefore, it is advantageous to make it as easy
as possible to repair or replace these items without breaking into
any process fluid flow lines attached to each of the individual
pumping heads 204'. Drain and fill tubes (as are well known) are
provided to make it easy to remove and refill the actuating fluid
in the pump drive assembly. To remove the actuating mechanism 136'
one only needs to follow a two-step process:
[0135] 1. Drain the actuating fluid out of the pump 200' using
drain and fill tubes that are built into the pump 200.
[0136] 2. Remove the top accessible screws to detach the drive
system from the main body of the pump 200'.
[0137] This process will be described in further detail below.
[0138] A quick disconnect connection 1008, is be used between the
central body 208' and a cartridge valve subassembly 1002 (See FIG.
25). While the details of such a quick disconnection 1008 are not
specifically shown in the drawings, such quick disconnections are
well known for connecting and disconnecting two machined parts
(while proper alignment and connection between its various
flowpaths are maintained).
[0139] Also, a quick disconnect connection 1008 between the central
body 208' and the cartridge valve subassembly 1002 may be made
using a tube that could is split to direct actuation fluid to
another pump head assembly 204' with, for example, five separate
pump heads on it. The effect of this would be that the actuating
mechanism 136' could be used to pump through numerous (for example,
five or more) pump heads.
[0140] Alternatively, as can be seen in FIG. 25, each of the
pumping heads 204' may be removed from the pumping head mounting
plate 1010 while maintaining the integrity of the seals directed to
the process fluid. Again, this provides for easy maintainability of
the pump 200'
[0141] Another possible means to make maintaining the pump easier
is to use either a process fluid chamber or an actuating fluid
chamber of one or more of the pumping heads to store process fluid
during a maintenance operation or a process operation and to store
actuating fluid during a maintenance operation or a process
operation. This can be accomplished utilizing software to transfer
all such fluids to one or more of these chambers in order to
maintain a different pumping head on the pump.
[0142] Finally, a three way valve can be used to easily switch flow
from one pumping head to another to provide redundancy in the event
of a problem with one of the pumping heads.
[0143] The foregoing description is of an exemplary and preferred
embodiment of multiple dispense head pumps 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 is intended to invoke paragraph six of 35 U.S.C.
.sctn.112 unless the exact words "means for" or "steps for" are
followed by a participle.
* * * * *