US20070177998A1

US20070177998A1 - Liquid chemical supply system

Info

Publication number: US20070177998A1
Application number: US11/655,081
Authority: US
Inventors: Takashi Kato
Original assignee: CKD Corp
Current assignee: CKD Corp
Priority date: 2006-01-27
Filing date: 2007-01-19
Publication date: 2007-08-02
Also published as: KR20070078699A; JP2007198272A; JP4694377B2

Abstract

A liquid chemical supply system includes a liquid chemical pump having a pump chamber for supplying a liquid chemical and a volume variation member that will vary the volume of the pump chamber, and will intake or discharge the liquid chemical based upon a change in the volume of the pump chamber in accordance with the volume variation member. The system also comprises an operation means for causing the volume variation member to operate, an operation amount detection means for detecting the operation amount of the volume variation member, a displacement control means for performing displacement control so that the volume variation member will be displaced by the operation means when liquid chemical ports that lead to the pump chamber are in the closed state, and a determination means for determining the presence or absence of gas inside the pump chamber based upon the operation amount detection results from the operation amount detection means during displacement control.

Description

The present application claims priority based on Japan Patent Application No. 2006-018504 filed on Jan. 27, 2006, and the entire contents of that application is incorporated by reference in this specification.

FIELD OF THE INVENTION

The present invention relates to a liquid chemical supply system that employs a liquid chemical pump in order to perform intake and discharge of a liquid chemical, and also relates to a liquid chemical supply system that is suitable for a semiconductor manufacturing device which uses a liquid chemical in order to, for example, apply to a semiconductor.

BACKGROUND ART

A liquid chemical pump is provided with a semiconductor manufacturing device in order to apply a predetermined quantity of liquid chemical to a semiconductor wafer. One of the liquid chemical pumps is designed such that a pump chamber in which liquid chemical is stored and a pressure application chamber that introduces compressed air are separated by a separation member such as a bellows, a diaphragm, or the like. In this chemical pump, the separation member is deformed by variably adjusting the air pressure inside the pressure application chamber in order to perform the intake and discharge of the liquid chemical.
In a system in which the liquid chemical pump described above is employed, liquid chemical supply lines are provided that communicate with liquid chemical tanks and the like. Thus liquid chemical is sequentially supplied to the liquid chemical pump via the liquid chemical supply lines. Then, in response to the deformation of the separation member, liquid chemical is drawn into the pump chamber of the liquid chemical pump, and is thereafter discharged to a liquid chemical discharge line.
In the aforementioned system, when, for example, the remaining amount of liquid chemical inside a liquid chemical tank that serves as a liquid chemical supply source has been reduced, air (gas) will mix with the liquid chemical that flows through the liquid chemical supply line, and that air will flow into the pump chamber of the liquid chemical pump. When this occurs, the liquid chemical tank must be replenished with liquid chemical, and the air inside the pump chamber must be removed. In connection with this, technology has been proposed in which a liquid level detection sensor is provided on the liquid chemical tank, and notification of a decrease in the remaining liquid chemical is provided in response to the liquid level detected by the liquid level detection sensor (see, for example, Japan Published Patent Application No. 2000-223393).

SUMMARY OF THE INVENTION

In a situation in which air enters into the pump chamber of a liquid chemical pump, for example, when the liquid chemical inside a liquid chemical tank is exhausted, the air will be removed from the pump chamber by, for example, repeatedly performing intake and discharge with the liquid chemical pump. However, if it is not confirmed whether or not the air has been completely removed therefrom before the liquid chemical pump is used with air remaining inside the pump chamber, liquid chemical may no longer be able to be discharged as intended. In particular, when the discharge of a fixed quantity of liquid chemical is attempted, the precision of the fixed quantity may be reduced. In addition, it is assumed that air will enter the pump chamber even in situations other than when the liquid chemical inside a liquid chemical tank is exhausted, and thus technology for determining the presence or absence of air inside a pump chamber is desired.
An object of the present teaching is primarily to provide a liquid chemical supply system that can accurately detect the presence of gas inside a pump chamber of a liquid chemical pump, and can optimally perform discharge supply of liquid chemical by means of a liquid chemical pump.
A first liquid chemical supply system that is one aspect of the present teaching can be constructed as follows. The first liquid chemical supply system may be comprised of a liquid chemical pump having a pump chamber for supplying a liquid chemical, and a volume variation member that will vary the volume of the pump chamber, and can intake and discharge liquid chemical based upon a change in the volume of the pump chamber in accordance with the volume variation member. The first liquid chemical supply system can also have an operation means for causing the volume variation member to operate, and an operation amount detection means for detecting the operation amount of the volume variation member.
In addition, the liquid chemical supply system may be comprised of a displacement control means for performing displacement control so that the volume variation member will be displaced by the operation means when liquid chemical ports to the pump chamber are closed, and a determination means for determining the presence or absence of gas inside the pump chamber based upon the operation amount detection results by the operation amount detection means during displacement control.
According to the first liquid chemical supply system, when the liquid chemical gateway to the pump chamber is closed, i.e., when the pump chamber is closed, deformation control can be performed so that the volume variation member will deform by means of the operation means, and the presence or absence of gas inside the pump chamber can be detected based upon the operation amount detection results at that time from the operation amount detection means.
In other words, gas is a compressive fluid, in contrast to the liquid chemical being a non-compressive fluid. Therefore, if only liquid chemical is present inside the pump chamber, the volume inside the pump chamber will not change (the volume variation member will not move), even if deformation control of the volume variation member is performed when the pump chamber is sealed. In contrast, if a gas has entered into the pump chamber, when deformation control of the volume variation member is performed with the pump chamber sealed, the volume inside the pump chamber will change (the volume variation member will move) due only to the compression or expansion of the gas. Therefore, the presence or absence of gas inside the pump chamber can be detected based upon the operation amount detection results from the operation amount detection means. As a result, the presence of gas inside the pump chamber of the liquid chemical pump can be accurately detected, and the discharge supply of liquid chemical can be optimally performed by the liquid chemical pump.
For example, when gas discharge (air removal) is performed after gas has entered into the pump chamber, it will also be possible to accurately determine whether or not the gas has been completely discharged.
A second liquid chemical supply system that is another aspect of the present teaching can be constructed as follows. The second liquid chemical supply system may be comprised of a liquid chemical pump having a pump chamber for supplying a liquid chemical, a volume variation member that will vary the volume of the pump chamber, and an urging means for urging the volume variation member in a predetermined direction. The liquid chemical pump can have the volume variation member operated in resistance to the urging force of the urging means and may intake and discharge the liquid chemical based upon a change in the volume of the pump chamber in accordance with that operation. The second liquid chemical supply system may also have an operation means for causing the volume variation member to operate, and an operation amount detection means for detecting the operation amount of the volume variation member.
In addition, the second liquid chemical supply system can be comprised of a displacement control means for performing displacement control of the volume variation member by the operation means by resisting the urging force of the urging means when the liquid chemical intake port to the pump chamber is open, and thereafter, for closing the pump chamber and releasing the displacement control of the volume variation member by the operation means, and a determination means for determining the presence or absence of gas inside the pump chamber based upon the operation amount detection results by the operation amount detection means, after displacement control of the volume variation member is released by the displacement control means.
According to the second liquid chemical supply system, when the liquid chemical intake port to the pump chamber is open, deformation control of the volume variation member by the operation member can be performed in resistance to the urging force of the urging means, and thereafter, the pump chamber may be sealed and the displacement control of the volume variation member by the operation means can be released. At this point, with the deformation control of the volume variation member in the released state, a force will be applied that attempts to return the urging means to its original state. Then, after the deformation control of the volume variation member is released, the presence or absence of gas inside the pump chamber may be determined based upon the operation amount detection results from the operation amount detection means.
The liquid chemical pump may also be constructed to have a pressure application chamber that is separated from the pump chamber by the volume variation member, and the volume variation member may operate by means of the operation means adjusting the gas pressure inside the pressure application chamber.
Here, the displacement control means preferably performs displacement control of the volume variation member with the adjustment of the gas pressure inside the pressure application chamber by the operation means.
In this construction, the pressure of the gas supplied to the pressure application chamber is adjusted by the operation means in order to perform deformation control of the volume variation member, and the volume variation member will move in accordance with that displacement control. Then, when deformation control of the volume variation member is performed as in the first or second liquid chemical supply system described above, the gas pressure inside the pressure application chamber will be adjusted by the operation means.
In addition, the liquid chemical supply system preferably comprises a feedback control means for setting a target operation amount of the volume variation member during intake or discharge by the liquid chemical pump, and for performing feedback control of the operation of the operation means so that the actual operation amount derived from the detection results by the operation amount detection means matches the target operation amount.
Here, feedback control of the operation amount will be performed during the intake or discharge of liquid chemical by the liquid chemical pump so that the target operation amount of the volume variation member matches the actual operation amount. Because there is a general correlation between the operation amount of the volume variation member and the change in volume of the pump chamber, by performing operation amount feedback control as described above, the change in the volume of the pump chamber can be controlled substantially as intended. In this way, it will be possible to control the intake flow rate or the discharge flow rate of the liquid chemical to an intended flow rate with a high degree of precision.
Here, the operation amount detection means is an indispensable constituent in the performance of operation amount feedback control. In that regard, if the detection results of the operation amount detection means are employed to detect the presence or absence of gas inside the pump chamber, a new sensor or the like is not needed in order to determine the presence or absence of gas. Therefore, this can be preferable from the perspective of simplifying the construction of the system.
As another preferable construction, when determining the presence or absence of gas inside the pump chamber, the liquid chemical supply system may be designed to estimate the amount of gas (air volume) inside the pump chamber based upon the operation amount detection results from the operation amount detection means.
In the event that gas has entered into the pump chamber of the liquid chemical pump, the operation amount of the volume variation member will change in response to the amount of gas therein, and the operation amount of the volume variation member will increase as the amount of gas increased. At this point, there is thought to be a correlation between the amount of gas and the operation amount of the volume variation member. Thus, according to this construction, the amount of gas inside the pump chamber can be calculated appropriately.
In addition, the liquid chemical supply system may be designed to supply liquid chemical stored inside a storage container (a liquid chemical tank, etc.) to the liquid supply pump through a liquid chemical line.
Here, when determining the presence or absence of gas inside the pump chamber, the liquid chemical supply system will preferably determine that the liquid chemical stored inside the storage container has fallen below a predetermined amount based upon the operation amount detection results from the operation amount detection means.
When liquid chemical stored in the storage container decreases, gas (air) will flow into the pump chamber of the liquid chemical pump through the liquid chemical line in response thereto. In that situation, if the presence or absence of gas in the pump chamber can be accurately determined as described above, it can be easily determined whether there is a predetermined amount or lower of the liquid chemical inside the storage container (including a state in which there is no liquid chemical therein).
Here, in the event that the amount of gas (the estimated amount) inside the pump chamber is greater than a normal amount, it may be determined that the liquid chemical inside the storage container is less than the predetermined amount. Or, in the event that the amount of gas (the estimated amount) has gradually increased in the course of repeatedly performing the intake and discharge of liquid chemical, it may be determined that the liquid chemical inside the storage container is less than the predetermined amount.
In addition, the liquid chemical supply system may comprise a single pump chamber, or may comprise a plurality of pump chambers.
When the liquid chemical supply system comprises a single pump chamber, the intake and discharge of liquid chemical will be repeatedly and alternately executed with the pump chamber.
When the liquid chemical supply system comprises a plurality of pump chambers, a predetermined sequence will be employed in order to perform the intake and discharge of liquid chemical with the plurality of pump chambers.
Here, the determination means will preferably determine the presence or absence of gas inside the pump chamber(s) after the completion of the intake of liquid chemical into each pump chamber and before liquid chemical discharge is performed, or after the completion of discharge and before liquid chemical intake is performed.
With these configurations, the presence or absence of gas inside the pump chamber can be accurately determined while the liquid chemical pump is performing intake and discharge of liquid chemical. Thus, even if gas has entered into the pump chamber unexpectedly, his can be determined timely.
Note that in the case of a liquid chemical pump that alternately and repeatedly intakes and discharges liquid chemical with the same pump chamber, then in a system in which a single liquid chemical pump is employed, the discharge of liquid chemical will be performed intermittently. In this respect, it will be possible to continuously discharge liquid chemical without pausing the discharge thereof, by employing a plurality of pump chambers in a predetermined sequence in order to perform intake and discharge operations.
In addition, the volume change operation of the pump chamber(s) by the volume variation member is preferably quicker during liquid chemical intake than during liquid chemical discharge.
According to this construction, the volume change operation of the pump chamber by the volume variation member will be performed promptly during liquid chemical intake. Because of that, during the surplus time period after liquid chemical intake (the time remaining until the next liquid chemical intake), the presence or absence of gas inside the pump chamber can be determined. At this point, there will be a correlation between speed of the change in the volume of the pump chamber and the liquid chemical flow rate during liquid chemical intake or liquid chemical discharge. The liquid chemical flow rate during liquid chemical intake may have a comparatively rough accuracy, but in contrast, the liquid chemical flow rate during liquid chemical discharge must be controlled with a high degree of accuracy. In this respect, a construction in which the volume change operation of the pump chamber during liquid chemical intake is quicker than during liquid chemical discharge, can be more suitable for controlling the liquid chemical flow rate with a high degree of accuracy during liquid chemical discharge, when compared to the opposite construction (a construction in which the volume change operation of the pump chamber during liquid chemical discharge is quicker than during liquid chemical intake).
Another preferable construction is one in which the liquid chemical supply system comprises a means for providing notification that the determination means has determined that gas has entered the pump chamber.
According to this construction, when it has been determined that gas has entered the pump chamber, a user can quickly know that gas has entered the pump chamber because he or she will be notified of that fact. Thus, in the event that, for example, the liquid chemical in the liquid chemical supply source (the liquid chemical tank) has been exhausted, replenishment of the liquid chemical can be performed immediately.
The above and other objects, features, and advantages of the present invention will be apparent from the following description when taken in conjunction with the accompanying drawings which illustrate preferred embodiments of the present invention by way of example.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

First Embodiment

A first embodiment of the present invention will be described below in accordance with the drawings. The present embodiment is embodied as a liquid chemical supply system which is used in a production line of a semiconductor device or the like. The basic construction of this system will be described based upon FIG. 1.
The liquid chemical supply system of FIG. 1 comprises a liquid chemical pump 10 for performing the intake and discharge of liquid chemical. A bellows-type diaphragm 12 as a volume variation member is housed inside a pump housing 11 of the liquid chemical pump 10. A pump chamber 13 and a pressure application chamber 14 are separately formed by means of the bellows-type diaphragm 12. The bellows-type diaphragm 12 has a bellows 15 that is compressible in the axial direction, and a diaphragm plate 16 that is attached to one end of the bellows 15 (the lower end in the drawing), and the other end of the bellows 15 (the upper end in the drawing) is fixed to an annular fixing plate 17. The diaphragm plate 16 will move in accordance with the compression of the bellows 15, and the volume of the pump chamber 13 and the pressure application chamber 14 will each change. Here, because the total volume of the pump chamber 13 and the pressure application chamber 14 will not change regardless of the compression of the bellows 15, an increase in the volume of the pump chamber 13, for example, will correspond to a decrease in the volume of the pressure application chamber 14 (the same will of course be true in the opposite situation).
An intake port 18 and a discharge port 19, which communicate with the pump chamber 13, are formed in the pump housing 11; an intake line 21 is connected to the intake port 18; and a discharge line 22 is connected to the discharge port 19. An intake valve 23 that is an intake side on-off valve is provided on the intake line 21, and the intake valve 23 is opened and closed in response to the electrically conductive state of a solenoid valve 24. In addition, a discharge valve 25 that is a discharge side on-off valve is provided on the discharge line 22, and the discharge valve 25 is opened and closed in response to the electrically conductive state of a solenoid valve 26. For example, the intake valve 23 and the discharge valve 25 corresponds to air operated valves that are opened and closed by means of air pressure, the air pressure applied to each valve 23, 25 is adjusted in response to the electrically conductive states of the solenoid valves 24, 26, and each of the valves 23, 25 will open and close in accordance therewith.
The intake line 21 corresponds to a liquid chemical supply passage for supplying liquid chemical to the pump chamber 13. Liquid chemical stored in a liquid chemical tank not shown in the drawings (a liquid chemical storage container), or liquid chemical supplied from a liquid chemical supply line of the foundry, will flow through the intake line 21 and be supplied to the pump chamber 13. Liquid chemical will be supplied to the pump chamber 13 in this way. The discharge line 22 forms a liquid chemical discharge passage for discharging liquid chemical stored in the pump chamber 13, and the liquid chemical to be discharged from the pump chamber 13 will flow through the discharge line 22 and be supplied to a liquid chemical discharge nozzle (not shown in the drawings). The liquid chemical discharge nozzle is pointed downward, and is adjusted such that liquid chemical will be dripped onto a central position of a semiconductor wafer placed on a rotating plate or the like. The task of applying liquid chemical to the surface of a semiconductor wafer can be performed by dripping a suitable amount of liquid chemical onto the wafer from the liquid chemical supply nozzle.
A discharge port 27 that communicates with the pressure application chamber 14 is formed in the same pump housing 11, and an electropneumatic regulator 28 is connected to the discharge port 27. The electro-pneumatic regulator 28 corresponds to an air pressure adjusting means for adjusting the air pressure inside the pressure application chamber 14, and will be switched between a compressed air supply state that supplies compressed air to the pressure application chamber and an open atmosphere state that discharges the compressed air inside the pressure application chamber 14 to the exterior, by switching a solenoid-type switching valve that the electropneumatic regulator 28 is equipped with.
A case unit 31 is installed in the pump housing 11, and a long thin cylindrical rod 33 is slidably fitted into a through hole 32 formed in the pump housing 11 so as to project out on the case unit 31 side. In other words, one end of the rod 33 projects inside the pressure application chamber 14, and the other end of the rod 33 projects in the interior space surrounded by the case unit 31. The diaphragm plate 16 of the bellows-type diaphragm 12 is fixed to the end of the rod 33 on the pressure application chamber 14 side, and the rod 33 will move reciprocally in the vertical direction of the drawing in accordance with the movement of the diaphragm plate 16 (i.e., the compression operation of the bellows 15).
In addition, a spring receiving plate 34 is attached to the end of the rod 33 on the case unit 31 side, and a compression coil spring 35 is interposed between the spring receiving plate 34 and the wall surface of the pump housing 11. The rod 33 is always urged upward in the drawing by means of the urging force of the compression coil spring 35. The compression coil spring 35 corresponds to an urging means for urging the bellows-type diaphragm 12 in a direction that is opposite that of the air pressure inside the pressure application chamber 14.
Due to the aforementioned construction, when no compressed air has been introduced into the pressure application chamber 14 (the open atmosphere state), the bellows 15 of the bellows-type diaphragm 12 will be compressed due to the urging force of the compression coil spring 35, and the volume of the pump chamber 13 will increase. At this point, by opening the intake valve 23 and closing the discharge valve 25, the intake line 21 will communicate with the pump chamber 13, and liquid chemical will be drawn into the pump chamber 13. On the other hand, when in the compressed air supply state, compressed air supplied from an air source not shown in the drawings will flow through the electropneumatic regulator 28 and the discharge port 27 and be introduced into the pressure application chamber 14. Thus the bellows 15 will extend and the volume of the pump chamber 13 will decrease in response to the balance between the air pressure inside the pressure application chamber 14 and the urging force of the compression coil spring 35. At this point, liquid chemical stored in the pump chamber 13 will be discharged through the discharge line 22 by closing the intake valve 23 and opening the discharge valve 25.
A position detector 36 for detecting the amount of movement of the rod 33 (i.e., the amount of compression of the bellows 15) is provided inside the case unit 31. Note that in FIG. 1, reference number 37 indicates a linear bearing for ensuring that the rod 33 is capable of reciprocating, and reference number 38 indicates an axial seal for preventing air leaks from the pressure application chamber 14.
A controller 40 is an electronic control device that is primarily comprised of a micro computer having a CPU, various memories, and the like, and will control the intake and discharge states of the liquid chemical by means of the liquid chemical pump 10. Intake/discharge signals, intake speed commands, and discharge flow rate commands from a administration computer (not shown in the drawings) that administrates the entire system, and position detection signals from the position detector 36, will be input into the controller 40. In addition, the controller 40 will control the open and close state of the intake valve 23 and the discharge valve 25 as the electrically conductive or non-electrically conductive state of the solenoid valves 24 and 26 each time signals are input therein. In addition, the controller 40 will compute control command values (air pressure command values) for the electropneumatic regulator 28 in order to control the state of the electropneumatic regulator 28. At this point in particular, the controller 40 will perform feedback control of the electropneumatic regulator 28 so that the movement speed of the diaphragm plate 16 (rod 33) in accordance with the extension and contraction of the bellows 15 during the intake and discharge of liquid chemical will achieve a target movement speed. Furthermore, the controller 40 will compute the discharge flow rate based upon the position detection signals of the position detector 36, and will output the computed value to the administration computer or the like.
Next, FIG. 2 will be employed in order to provide a summary of the discharge flow rate control by the controller 40.
The controller 40 will calculate the movement speed of the diaphragm plate 16 during liquid chemical intake based upon an intake speed command, and will calculate the movement speed of the diaphragm plate 16 during liquid chemical discharge based upon a discharge flow rate command. Here, during the calculation of the movement speed during liquid chemical discharge, the calculation of the movement speed will be performed based upon pump discharge characteristics that describe the movement speed in relation to the discharge flow rate. More specifically, the relation between the amount of movement of the diaphragm plate 16 and the amount of discharge of the liquid chemical pump 10 shown in FIG. 3. According to FIG. 3, the pump discharge amount is linear with respect to the amount of movement of the diaphragm plate 16, and this relation is employed in order to calculate the movement speed of the diaphragm plate.
Here, the discharge flow rate is represented as “Q”, the bellows effective area is represented as “A”, the movement distance of the diaphragm plate 16 is represented as “X”, and the movement time of the diaphragm plate 16 is represented as “t”. Then the pump discharge characteristics will be mathematically expressed as
Q=A*X/t.

In this equation, “X/t” corresponds to the movement speed of the diaphragm plate 16, and the movement speed calculation can be performed by means of this equation.

In addition, the controller 40 will select either the movement speed during intake, or the movement speed during discharge, based upon intake/discharge signals. The movement speed selected at this time corresponds to the target movement speed of the diaphragm plate 16. Then, the air pressure command value will be calculated based upon the deviation between the target movement speed of the diaphragm plate 16 and the actual movement speed of the diaphragm plate 16, and the drive of the electropneumatic regulator 28 will be controlled based upon the air pressure command value.
Here, the controller 40 will calculate the actual movement speed of the diaphragm plate 16 based upon the detection results from the position detector 36 provided in the liquid chemical pump 10. The calculated value of the actual movement speed will be employed in the feedback control of the electropneumatic regulator 28, and will be employed in the computation of each discharge flow rate. With regard to the computation of the discharge flow rate, the controller 40 will employ the pump discharge characteristics described above (e.g., the relation shown in FIG. 3) in order to convert the actual movement speed of the diaphragm plate 16 to the discharge flow rate, and that result will be output to the administration computer or the like as a discharge flow rate value.
In a liquid chemical supply system having the aforementioned construction, when gas is mixed with the liquid chemical that flows through the intake line 21, that gas will flow into the pump chamber 13 of the liquid chemical pump 10. When this occurs, there is a possibility that errors will be produced in the amount of liquid chemical to be discharged, and thus the discharge amount control accuracy will decline. In addition, when the liquid chemical in the liquid chemical tank (the liquid chemical supply source) is reduced, or when the liquid chemical is exhausted, gas will enter into the pump chamber 13 as described above. In this embodiment, a method is proposed which detects whether gas has entered into the pump chamber 13 of the liquid chemical pump 10 based upon the air pressure produced by the electropneumatic regulator 28 and the detection results of the position detector 36.
Briefly, gas is a compressive fluid, in contrast to liquid chemical being a non-compressive fluid. Because of that, in a state in which the pump chamber 13 is filled with liquid chemical, and the ports of the pump chamber 13 are closed (a state in which the intake valve 23 and the discharge valve 25 are both closed), the bellows 15 will not extend or contract, regardless of whether the air pressure produced by the electropneumatic regulator 28 is increased or decreased. Thus the amount of extension or contraction of the bellows 15 (the bellows length) detected by the position detector 36 will not change. In contrast, when gas has entered into the pump chamber 13, the bellows 15 will extend and contract when the air pressure produced by the electropneumatic regulator 28 is increased or decreased in a state in which the gateways to the pump chamber 13 are closed (a state in which the intake valve 23 and the discharge valve 25 are both closed). The extension or contraction of the bellows will be detected by the position detector 36.
This basic principle will be described by means of FIG. 4. In FIG. 4, (a) shows a situation in which the volume ratio of a cylinder S (a sealed space) is “liquid:gas=1:0”, (b) shows a situation in which the volume ratio of the cylinder S is “liquid:gas=1:1”, and (c) shows a situation in which the volume ratio of the cylinder S is “liquid:gas=0:1”. In addition, FIG. 4 illustrates the amount of displacement ΔX of a piston P when a force F1 is applied in the downward direction in the drawing on the piston P.
In FIG. 4( a), only liquid is contained inside the cylinder S, and the piston P will not be displaced (ΔX=0) even if the force F1 is applied to the piston P. In contrast, in FIGS. 4( b) and 4(c), the piston P will be displaced in response to the application of the force F1 on the piston P by only the amount of displacement ΔX corresponding to the expansion of the gas inside the cylinder S. Accordingly, the presence or absence of gas in the cylinder S can be determined by whether or not the piston P is displaced.
Here, the amount of displacement ΔX of the piston P corresponds to the amount of gas (air volume) inside the cylinder S, and this relation approximates the relation shown in FIG. 5. According to FIG. 5, if the amount of displacement ΔX is known, the amount of gas in the cylinder S (air volume) can be determined. The relation of FIG. 5 is based upon the equation of state of a gas (PV=nRT).
In the system construction of FIG. 1, a determination of the presence of air during both intake and discharge of liquid chemical will be performed as shown in FIG. 6. In FIG. 6, (a) shows the change in air pressure (i.e., the change in pressure in the pressure application chamber 14) due to the electropneumatic regulator 28, (b) and (c) show the change between the compressed state and the extended state of the bellows in the liquid chemical pump 10, (d) shows the change between the open state and closed state of the intake valve 23, and (e) shows the change between the open state and closed state of the discharge valve 25. Note that amongst (b) and (c), (b) shows a situation in which air is not present in the pump chamber 13, and (c) shows a situation in which air is present in the pump chamber 13. In the present example, the controller 40 will perform an air presence determination between the liquid chemical intake process (“t1” to “t2” of FIG. 6) and discharge process (“t3” to “t4” of FIG. 6) performed by the liquid chemical pump 10.
In FIG. 6, first at timing t1, the intake valve 23=open, the discharge valve 25=closed, and in this state the air pressure will be gradually reduced by means of the electropneumatic regulator 28. In accordance with that, the bellows 15 will be compressed, and the liquid chemical in the pump chamber 13 will be drawn in through the intake line 21. Then, at timing “t2”, the intake valve 23 will be closed.
At timing “t2”, liquid chemical intake into the pump chamber 13 will be completed, and the pump chamber 13 will be sealed. In this state, the electropneumatic regulator 28 will continue to reduce the air pressure. Note here that the air pressure will be changed stepwise to a low pressure state at timing “t2”. At this point, if no air has entered into the pump chamber 13, the bellows 15 will not be compressed any further, as shown in FIG. 6( b). In contrast, if air has entered into the pump chamber 13, the bellows 15 will be compressed (circular part “A” in FIG. 6) in response to the change in air pressure, as shown in FIG. 6( c). The presence of air can be determined by detecting the compression of the bellows 15 by means of the position detector 36. If it has been determined that the intrusion of air has occurred, a signal for providing notification of the intrusion of air will be output from the controller 40 to an alarm device or the like.
At this time in particular, the controller 40 estimates the degree of air intrusion (i.e., the air volume inside the pump chamber 13) based upon the detection results of the position detector 36. Then, an alarm is provided if the estimated air volume is above a predetermined quantity. In another way, the controller 40 can compare the estimated air volume and a predetermined liquid depletion value, and if the air volume> the liquid depletion value, then it may be assumed that the liquid chemical in the liquid chemical supply source (the liquid chemical tank) has been exhausted. Furthermore, if the occurrence of the intrusion of air has been repeatedly determined a predetermined number of times with an air intrusion determination performed during each liquid chemical intake, or if the air volume is trending upward (if the air volume has been gradually increasing), then an alert may be provided or a liquid depletion determination may be made.
Thereafter, at timing “t3”, the discharge valve 25 will be opened, and in this state the air pressure will be gradually increased by means of the electropneumatic regulator 28. In accordance with this, the bellows 15 will be extended, and liquid chemical in the pump chamber 13 will be discharged to the discharge line 22. Then, the discharge valve 25 will be closed at timing “t4”. Thereafter, the same operations will be repeated at timing “t1” to “t4”.
An actual liquid chemical supply system is provided with a plurality of liquid chemical pumps 10, and by repeatedly and sequentially executing a discharge operation and an intake operation with each pump 10, a continuous liquid chemical supply operation can be achieved. FIG. 7 shows the overall construction of a system having two liquid chemical pumps 10 a and 10 b. Both of the two liquid chemical pumps 10 a and 10 b shown in FIG. 7 have the same construction as the liquid chemical pump 10 described in FIG. 1, and the same reference numbers are used with the constituent elements of each pump, and thus a description thereof will be omitted. Note that the intake line 21 of each liquid chemical pump 10 a and 10 b is connected to a common intake port (a liquid chemical tank or a liquid chemical line in a foundry), and the discharge lines 22 thereof are connected to a common discharge port (a liquid chemical discharge nozzle).
In FIG. 7, the bellows 15 is compressed on the left side of the liquid chemical pump 10 a, and thereafter the discharge of liquid chemical stored in the pump chamber 13 will be performed by extending the bellows 15. In addition, the bellows 15 is extended on the right side of the liquid chemical pump 10 b, and thereafter liquid chemical intake into the pump chamber 13 will be performed by compressing the bellows 15.
The controller 40 will operate the intake valves 23 and the discharge valves 25 in order to switch between the open and closed state based upon the input of signals as described above, and will control the two liquid chemical pumps 10 a and 10 b. The controller 40 will also calculate the control command values (the air pressure command values) for each electropneumatic regulator 28 in order to control the electropneumatic regulators 28 by means of these command values. In addition, the controller 40 has the air intrusion determination function described above, and will execute an air intrusion determination for each pump 10 a and 10 b in response to the detection results of the position detectors 36 provided in each liquid chemical pump 10 a and 10 b.
FIG. 8 is a timing chart for describing the liquid chemical discharge operation in the present liquid chemical supply system. In FIG. 8, a continuous liquid chemical supply onto a semiconductor wafer will be achieved by sequentially repeating an intake operation and a discharge operation with the two liquid chemical pumps 10 a and 10 b. For the sake of convenience in describing FIG. 8, one liquid chemical pump 10 will be referred to as pump (A), and the other liquid chemical pump 10 will be referred to as pump (B). Accordingly, the valves of pump (A) are separately referred as intake valve (A) and discharge valve (A), and the valves of pump (B) are separately referred as intake valve (B) and discharge valve (B).
Prior to timing “a”, pump (A) will be in the state that liquid chemical pump 10 a is in as shown in FIG. 7, pump (B) will be in the state that liquid chemical pump 10 b is in as shown in FIG. 7, and the intake valves and discharge valves will all be closed. After timing “a”, liquid chemical intake and discharge will be performed with each pump in response to a START signal.
Specifically, on the pump (A) side, after the discharge valve (A) has been opened at timing “a”, the bellows 15 will be extended in response to a rise in air pressure due to the electropneumatic regulator 28, and liquid chemical discharge will be performed (timing “b” to “g”). In addition, concurrent with the liquid chemical discharge of pump (A), the intake valve (B) on the pump (B) side will be opened at timing “c” to “d”, and the intake of liquid chemical will be performed.
After the intake of liquid chemical has been completed, with pump (B), a process of temporarily reducing the air pressure will be performed by means of the electropneumatic regulator 28 (timing “d” to “e”), and the presence or absence of air intrusion will be determined in response to the behavior of the pump with respect to the reduction in air pressure. At this point, when the extension and contraction of the bellows occurs in response to the reduction in air pressure, this will be detected by the position detector 36, and it will be determined that air has intruded into the pump chamber 13.
Thereafter, on the pump (B) side, the discharge valve (B) will be opened at timing “f”. At timing “g”, the bellows 15 will be extended in response to the rise in air pressure by means of the electropneumatic regulator 28, and liquid chemical discharge will be performed (timing “g” to “i”). At timing “h”, in which the intake of liquid chemical by pump (A) is completed, a process of temporarily reducing the air pressure will be performed by the electropneumatic regulator 28. Then, in the same way as described above, the presence or absence of air intrusion will be determined in response to the behavior of the pump with respect to the reduction in air pressure.
Thereafter, the intake/discharge operations will be sequentially performed with pumps (A) and (B), and liquid chemical will be continuously discharged from the tip of the liquid chemical discharge nozzle. According to the aforementioned series of steps, the discharge period “TA” by the pump (A) and the discharge period “TB” by the pump (B) will be set to be continuous, and the liquid chemical will be continuously discharged without pausing. In addition, because the discharge speed of the liquid chemical is controlled so as to be fixed, each discharge period “TA” and “TB” will be equal, and thus it will be possible to supply liquid chemical stably.
Here, when the intake speed and the discharge speed of the liquid chemical in each pump (A) and (B) is compared, the intake speed will be higher. In other words, the time needed for liquid chemical intake into the pump chamber 13 is shorter than the time needed for the discharge of liquid chemical. Thus, when the liquid chemical intake/discharge operation is repeatedly performed, the liquid chemical intake will proceed quickly, and the surplus time period after liquid chemical intake (the time remaining until the next liquid chemical intake) can be employed in order to perform an air intrusion determination inside the pump chamber 13. In this way, an air intrusion determination can be performed during the liquid chemical intake/discharge as described above, and each discharge period “TA” and “TB ” of the pumps (A) and (B) can be made equal.
Note that the liquid chemical flow rate during liquid chemical intake may have a comparatively rough accuracy, but in contrast, the liquid chemical flow rate during liquid chemical discharge must be controlled with a high degree of accuracy. In this respect, a construction in which the intake speed of the liquid chemical intake is quicker, as described above, can be more ideal for controlling the liquid chemical flow rate with a high degree of accuracy during liquid chemical discharge, when compared to the opposite construction (a construction in which the liquid chemical discharge speed is quicker).
According to the present embodiment described in detail above, the following superior effects will be obtained.
As the pump chamber 13 in the liquid chemical pump 10 is sealed and the air pressure is changed by means of the electropneumatic regulator 28, and an air intrusion determination is performed based upon the amount of bellows extension or contraction (the change in bellows length), air intrusion can be accurately detected in the pump chamber 13. The exhaustion of liquid chemical in the liquid chemical tank can also be determined based upon the results of the air intrusion detection. In addition, when an air removal operation is to be performed after air intrusion, it will also be possible to accurately determine whether or not all gas has been discharged. Thus, liquid chemical discharge supply can be ideally performed by means of the liquid chemical pump 10.
Since the system is constructed to perform feedback control of the movement speed of the diaphragm plate 16 that forms the bellows-type diaphragm 12 during liquid chemical intake or discharge (i.e., constructed to perform feedback control of the amount of operation thereof), the change in volume of the pump chamber 13 can be controlled as intended. In this way, it will be possible to control the liquid chemical intake flow rate or discharge flow rate at an intended flow rate with a high degree of accuracy.
In the performance of operation amount feedback control, the position detector 36 is an indispensable constituent. In the aforementioned construction in which the detection results of the position detector 36 are employed in order to determine air intrusion inside the pump chamber 13, a new sensor or the like is not needed in order to determine the intrusion of air. Therefore, this can be preferable from the perspective of simplifying the construction of the system. Although conventional technology is known in which a liquid level detection sensor is employed in order to detect the liquid level inside a liquid chemical tank, and determine when the liquid has been exhausted from the detection results of the sensor, the construction of the present embodiment can be simplified because a liquid level detection sensor is not needed.
The liquid chemical pump 10 will perform liquid chemical intake or discharge by using air pressure adjusted by the electropneumatic regulator 28 as a drive source. This differs from an electric system that performs flow rate control by means of an electric motor, and thus there will be no threat of damage due to heat, and can be ideally used with liquid chemical that requires temperature control. In addition, compared to the construction of an electric actuator, the construction of the pump drive can be simplified.
Due to a construction in which two liquid chemical pumps 10 are employed, and each pump 10 sequentially performs intake and discharge operations, the discharge of liquid chemical can be performed continuously and without pausing. In addition, as noted above, because the movement speed of the bellows-type diaphragm 12 (the diaphragm plate 16) is feedback controlled, and the time needed for each liquid chemical discharge in each pump is fixed, it will be possible to stably supply liquid chemical.
In continuous discharge which is performed by the liquid chemical pump 10, because an air intrusion determination will be performed after liquid chemical intake is completed and before the next liquid chemical discharge is performed, this determination can be performed at the appropriate time, regardless of whether air has unexpectedly intruded into the pump chamber 13.
Optimal liquid chemical discharge accuracy can be achieved because the system was designed such that the intake speed of the liquid chemical is higher than the discharge speed in the liquid chemical pump 10, and the surplus time period after liquid chemical intake (the time remaining until the next liquid chemical intake) will be employed in order to perform an air intrusion determination. Hence an air intrusion determination can be properly performed with a high degree of accuracy during liquid chemical discharge.

Second Embodiment

In the aforementioned embodiment, the air pressure was changed by the electropneumatic regulator 28 with the pump chamber 13 sealed in the liquid chemical pump 10, and an air intrusion determination was performed based upon the amount of extension or contraction of the bellows at that time. However, in the second embodiment, the aforementioned method is changed with respect to the air intrusion determination. In other words, in the present embodiment, after first opening the intake valve 23 in order to perform intake, the air pressure will be controlled with the electropneumatic regulator 28, and the bellows type diaphragm 12 will be displaced while resisting the urging force of the compression coil spring 35. Next, the pump chamber 13 will be sealed, and the air pressure control by the electropneumatic regulator 28 will be released in this state. Then, an air intrusion determination will be performed based upon the change in the bellows length at that time.
A summary of the air intrusion determination in the present embodiment will be described in detail by employing FIG. 9. Note that here, it will be assumed that air has intruded into the pump chamber 13.
As shown in FIG. 9( a), the intake valve 23=open, the discharge valve 25=closed, and the air pressure “Pin” of the electropneumatic regulator 28 will be controlled so that the bellows length will be a predetermined length X. At this point, the bellows type diaphragm 12 will be displaced (the bellows 15 is extending in the example illustrated) while resisting the urging force of the compression coil spring 35, in response to the increase in the air pressure “Pin”.
Next, as shown in FIG. 9( b), both the intake valve 23 and the discharge valve 25 will be closed and the pump chamber 13 will be sealed, and in this state the air pressure “Pin” of the electropneumatic regulator 28 will be zero. When this occurs, a force will be applied to the compression coil spring 35 that attempts to return it to its original state (the unloaded state). In other words, the spring force “F2” of the compression coil spring 35 will be applied downward in the drawing, and the air that has intruded into the pump chamber 13 will expand due to the spring force F2. In this way, the volume inside the pump chamber 13 will increase, and the bellows length will change by ΔX. The air intrusion can be determined by detecting the change in bellows length with the position detector 36. Note that when air does not intrude into the pump chamber 13, the volume of the pump chamber 13 will not change (ΔX=0), after the air pressure “Pin” of the electropneumatic regulator 28 reached zero.
With the present embodiment, the amount of change ΔX in the bellows length will depend on the spring characteristics of the compression coil spring 35, and the relation between the amount of change and the air volume will be as shown in FIG. 10. If the amount of change ΔX in the bellows length is determined by employing FIG. 10, the air volume inside the pump chamber 13 can be known.
According to the aforementioned second embodiment, like with the aforementioned first embodiment, in the event that air has intruded into the pump chamber 13, that air intrusion can be accurately detected. Thus, the discharge supply of liquid chemical can be optimally performed by the liquid chemical pump 10.
Note that the present invention is not limited to the embodiments disclosed above, and may for example be embodied as shown below.
The aforementioned embodiment was constructed such that in continuous discharge which is performed by the liquid chemical pump 10, an air intrusion determination will be performed in the period after the completion of liquid chemical intake and before the next liquid chemical discharge is performed (see FIG. 6). However, this may be changed, such that the air intrusion determination is performed in the period after liquid chemical discharge is completed and before the next liquid chemical intake is performed. In other words, instead of a construction in which the air intrusion determination is performed after the completion of liquid chemical intake, the construction may be one in which the air intrusion determination is performed before beginning liquid chemical intake.
The aforementioned embodiment was constructed such that an air intrusion determination will be performed each time a liquid chemical intake/discharge operation is repeated in the liquid chemical pump 10. However, an air intrusion determination may be performed each time a predetermined number of intake/discharge operations are performed. In addition, an air intrusion determination may also be performed in response to a command input by a user or the like.
In the aforementioned embodiment, when an air intrusion determination is to be performed, the air pressure was decreased step-wise by the electropneumatic regulator 28. However, instead of this, the air pressure may be increased step-wise by the electropneumatic regulator 28. In addition, the air pressure may be gradually decreased or increased by the electropneumatic regulator 28 when performing the air intrusion determination.
In the aforementioned embodiment, the electropneumatic regulator 28 will be open to the atmosphere when the air pressure is to be reduced inside the pressure application chamber 14. However, for example, the electropneumatic regulator 28 may be connected to a vacuum source, and the vacuum source can produce a negative pressure inside the pressure application chamber 14. The amount of operation of the bellows or the like can be freely controlled by managing the air pressure in this way. In this situation, the compression coil spring 35 provided in the case unit 31 can be eliminated.
In the aforementioned embodiment, a construction was adopted for the liquid chemical pump 10 in which the pump chamber 13 is separated from the pressure application chamber 14 by the bellows type diaphragm 12, and the bellows type diaphragm 12 operates in response to the air pressure inside the pressure application chamber 14 in order to perform the intake and discharge of liquid chemical. However, a liquid chemical pump having a different construction can be employed. For example, a diaphragm film may be employed as a volume variation member instead of the bellows type diaphragm 12. In addition, the volume variation member may be designed as an electric piston member, and the piston position may be adjusted by driving a motor or the like.
The aforementioned embodiment was constructed as a liquid chemical supply system comprising a plurality of liquid chemical pumps, and the plurality of liquid chemical pumps are combined together such that each pump is connected by means lines or the like. However, a pump unit may be adopted in which the plurality of liquid chemical pumps is combined into one. In this way, the number of lines and the like can be reduced, and the overall size of the system can be reduced.

BRIEF DESCRIPTION OF THE DRAWINGS

[FIG. 1] A diagram showing an overview of a liquid chemical supply system in an embodiment of the present invention.
[FIG. 2] A diagram showing an overview of the discharge flow rate control in a controller.
[FIG. 3] A diagram showing the discharge characteristics of a pump.
[FIG. 4] A diagram showing the piston displacement state during gas intrusion.
[FIG. 5] A diagram showing the relation between the amount of piston displacement and the air volume inside a cylinder.
[FIG. 6] A time chart for describing intake/discharge operations by the liquid chemical pump and an air intrusion determination.
[FIG. 7] A diagram showing an overview of a system having two liquid chemical pumps.
[FIG. 8] A time chart for describing the liquid chemical discharge operation.
[FIG. 9] A diagram for describing an overview of an air intrusion determination in a second embodiment.
[FIG. 10] A diagram showing the relation between the amount of movement in bellows length and the air volume inside the pump chamber.

Claims

1. A liquid chemical supply system, comprising:

a liquid chemical pump having a pump chamber for supplying a liquid chemical, and a volume variation member that will vary the volume of the pump chamber, and will intake and discharge the liquid chemical based upon a change in the volume of the pump chamber in accordance with the volume variation member;

an operation means for causing the volume variation member to operate;

an operation amount detection means for detecting the operation amount of the volume variation member;

a displacement control means for performing displacement control so that the volume variation member will be displaced by the operation means when liquid chemical ports to the pump chamber are closed; and

a determination means for determining the presence or absence of gas inside the pump chamber based upon the operation amount detection results by the operation amount detection means during displacement control.

2. The liquid chemical supply system according to claim 1, wherein in a liquid chemical supply system in which the liquid chemical pump has a pressure application chamber that is separated from the pump chamber by the volume variation member, and the volume variation member operates by means of the operation means adjusting the gas pressure inside the pressure application chamber; and

the displacement control means performs displacement control of the volume variation member with the adjustment of the gas pressure inside the pressure application chamber by means of the operation means.

3. The liquid chemical supply system according to claim 1, comprising a feedback control means for setting a target operation amount of the volume variation member during the intake and discharge by the liquid chemical pump, and for performing feedback control of the operation of the operation means so that the actual operation amount derived from the detection results by the operation amount detection means matches the target operation amount.

4. The liquid chemical supply system according to claim 1, wherein when determining the presence or absence of gas inside the pump chamber, the liquid chemical supply system will estimate the amount of gas inside the pump chamber based upon the operation amount detection results by the operation amount detection means.

5. The liquid chemical supply system according to claim 1, wherein in a liquid chemical supply system designed to supply liquid chemical stored inside a storage container to the liquid supply pump through a liquid chemical line; and

when determining the presence or absence of gas inside the pump chamber, the liquid chemical supply system will determine that the liquid chemical stored inside the storage container has fallen below a predetermined amount based upon the operation amount detection results by the operation amount detection means.

6. The liquid chemical supply system according to claim 1, wherein

when there is a single pump chamber, the intake and discharge of liquid chemical will be repeatedly and alternately executed with the pump chamber;

when there are a plurality of pump chambers, a predetermined sequence will be employed in order to perform the intake and discharge of liquid chemical with the plurality of pump chambers; and

the determination means will determine the presence or absence of gas inside the pump chamber(s) after the completion of the intake of liquid chemical into each pump chamber and before liquid chemical discharge is performed, or after the completion of liquid chemical discharge and before liquid chemical intake is performed.

7. The liquid chemical supply system according to claim 6, wherein the volume change operation of the pump chamber(s) by the volume variation member is quicker during liquid chemical intake than during liquid chemical discharge.

8. The liquid chemical supply system according to claim 1, comprising a means for providing notification that the determination means has determined that gas has entered the pump chamber.

9. A liquid chemical supply system, comprising:

a liquid chemical pump having a pump chamber for supplying a liquid chemical, a volume variation member that will vary the volume of the pump chamber, and an urging means for urging the volume variation member in a predetermined direction, the liquid chemical pump having the volume variation member operated in resistance to the urging force of the urging means, and will intake and discharge the liquid chemical based upon a change in the volume of the pump chamber in accordance with that operation;

an operation means for causing the volume variation member to operate;

a displacement control means for performing displacement control of the volume variation member by means of the operation means by resisting the urging force of the urging means when the liquid chemical intake port to the pump chamber is open, and thereafter, for closing the pump chamber and releasing the displacement control of the volume variation member by means of the operation means; and

a determination means for determining the presence or absence of gas inside the pump chamber based upon the operation amount detection results by the operation amount detection means, after displacement control of the volume variation member is released by the displacement control means.

10. The liquid chemical supply system according to claim 9, wherein in a liquid chemical supply system in which the liquid chemical pump has a pressure application chamber that is separated from the pump chamber by the volume variation member, and the volume variation member operates by means of the operation means adjusting the gas pressure inside the pressure application chamber; and

11. The liquid chemical supply system according to claim 9, comprising a feedback control means for setting a target operation amount of the volume variation member during the intake and discharge by the liquid chemical pump, and for performing feedback control of the operation of the operation means so that the actual operation amount derived from the detection results by the operation amount detection means matches the target operation amount.

12. The liquid chemical supply system according to claim 9, wherein when determining the presence or absence of gas inside the pump chamber, the liquid chemical supply system will estimate the amount of gas inside the pump chamber based upon the operation amount detection results by the operation amount detection means.

13. The liquid chemical supply system according to claim 9, wherein in a liquid chemical supply system designed to supply liquid chemical stored inside a storage container to the liquid supply pump through a liquid chemical line; and

14. The liquid chemical supply system according to claim 9, wherein

15. The liquid chemical supply system according to claim 14, wherein the volume change operation of the pump chamber(s) by the volume variation member is quicker during liquid chemical intake than during liquid chemical discharge.

16. The liquid chemical supply system according to claim 9, comprising a means for providing notification that the determination means has determined that gas has entered the pump chamber.