US20070297927A1

US20070297927A1 - Pump for Supplying Chemical Liquids

Info

Publication number: US20070297927A1
Application number: US11/665,969
Authority: US
Inventors: Katsuya Okumura; Shigenobu Itoh; Kazuhiro Sugata; Kazuhiro Arakawa
Original assignee: CKD Corp; Octec Inc
Current assignee: CKD Corp; Octec Inc
Priority date: 2004-10-29
Filing date: 2005-07-29
Publication date: 2007-12-27
Also published as: KR20070084586A; JP2006125338A; WO2006046338A1; KR101183216B1; JP4526350B2

Abstract

An opening 22 d of a supply/withdrawal passage 22 b is positioned at the center part of the internal wall surface 22 c of the operating chamber 26 (concave area 22 a), and a cross-shaped venting groove 22 e extending from the opening 22 d of the passage 22 b to the periphery of the wall surface 22 c is formed in the wall surface 22 c. Thus, an operating air in the chamber 26 is discharged (sucked) through the passage 22 b during drawing in the chemical liquid. Since the opening 22 d communicates with the venting groove 22 e extending to the periphery of the chamber 26, if the center of the diaphragm 23 covers the opening 22 d first, the operating air in the chamber 26 can be continuously evacuated (drew out) from the venting groove 22 e positioned on the outside of the center part which first comes into contact with the opening 22 d

Description

TECHNICAL FIELD

The present invention relates to a pump for supplying chemical liquids that is suitable for applying a predetermined volume of a chemical liquid, such as a photoresist liquid, to individual semiconductor wafers in the chemical-using process of, for example, a semiconductor manufacturing device.

BACKGROUND ART

In order to pump a chemical liquid such as a photoresist out of a bottle and apply a predetermined volume of this liquid to individual semiconductor wafers, a pump for supplying chemical liquids such as that disclosed in Patent Document 1, for example, is currently in use. This pump is divided by a diaphragm into a pump chamber and an operating chamber (a pressurization chamber in Patent Document 1), and driving the diaphragm by supplying air to or withdrawing air from the operating chamber, via a supply/withdrawal passage connected to the operating chamber, changes the volume inside the pump chamber, thereby causing the pump chamber to suction or discharge a chemical liquid.
When the pump chamber and the operating chamber are formed to be thin and the pump is made thin through the use of a diaphragm comprised of a flexible film, the diaphragm is secured at its perimeter, and consequently tends to deform more at its center. At the same time, to ensure efficient deformation of the entire diaphragm, it has been preferable to position the opening of the supply/withdrawal passage in the operating chamber in its center.
When the interior of the operating chamber is evacuated in order to draw the chemical liquid into the pump chamber or when the interior of the operating chamber is opened to the surrounding atmosphere in order to supply the pressurized chemical liquid, the diaphragm begins to deform at its center toward the operating chamber, with the result that the center tends to come into contact with the internal wall of the operating chamber first. In such a case, the center of the diaphragm blocks the opening of the supply/withdrawal passage while the area surrounding the center of the diaphragm does not contact the internal wall of the operating chamber. This slows down the deformation of the diaphragm toward the operating chamber, and moreover, may prevent the diaphragm from deforming fully. As a result, it may take a long time for the chemical liquid to fill the pump chamber or it may not be possible to supply the pump chamber with the specified volume of chemical liquid.
Patent document 1: Japanese patent application publication No. 2003-49778

DISCLOSURE OF THE INVENTION

A primary object of the present invention is to provide a pump for supplying chemical liquids that can ensure quick and reliable deformation of the diaphragm toward the operating chamber, and that can shorten the time needed for filling the pump chamber with a chemical liquid and ensure that the pump chamber is filled with a sufficient volume of chemical liquid.
A pump for supplying chemical liquids according to the present teaching is configured as described below. That is, in a pump for supplying chemical liquids in which the pump chamber and operating chamber are divided by means of a diaphragm comprised of a flexible film, the diaphragm deforms toward the pump chamber when the interior of the pump chamber is pressurized using an operating gas, thereby discharging the chemical liquid that has been supplied into the pump chamber; and when the interior of the operating chamber reaches a negative pressure because of the withdrawal of the operating gas or when the interior of the operating chamber is opened to the surrounding atmosphere, the diaphragm deforms toward the operating chamber, thereby drawing a chemical liquid into the pump chamber, and
a supply/withdrawal passage for supplying the operating gas to or withdrawing same from the operating chamber is formed in the pump housing, and the opening of the supply/withdrawal passage is provided in part of the internal wall surface of the operating chamber, and
a venting groove that extends from the opening of the supply/withdrawal passage to the periphery of the internal wall surface is formed on the internal wall surface of the operating chamber.
In this pump for supplying chemical liquids, the opening of the supply/withdrawal passage is provided in part of the internal wall surface of the operating chamber, and a venting groove is formed, which extends from the opening of the supply/withdrawal passage to the periphery of the interior wall surface. Here, when the chemical liquid is to be drawn in, the operating gas inside the operating chamber is evacuated (sucked out) through the supply/withdrawal passage. In this case, the diaphragm tends to deform from its center, which may cover the opening of the supply/withdrawal passage first. However, the opening of the supply/withdrawal passage is connected to the vent groove, which opens toward the periphery of the operating chamber as described above. Therefore, even when the diaphragm deforms from the center, thus covering the opening of the supply/withdrawal passage first, because the venting groove positioned on the outside of the contacted center is open, it is possible to continue to evacuate (draw out) the operating gas inside the operating chamber through the open venting groove. In this way, even when such uneven deformation occurs in the diaphragm, the diaphragm still quickly and reliably deforms toward the operating chamber, shortening the time needed for filling the pump chamber with the chemical liquid, and filling the pump chamber with a sufficient volume of chemical liquid.
Note that it is desirable to position the extension destination of the venting groove as close as possible to the periphery of the operating chamber, and it is best to extend it to the periphery. With such a configuration, the diaphragm will not block the venting groove until the diaphragm has sufficiently deformed toward the operating chamber, ensuring reliable evacuation (drawing out) of the operating gas from the operating chamber.
In a preferred embodiment of the pump for supplying chemical liquids, the internal wall surface of the operating chamber is circular in shape and the opening of the supply/withdrawal passage is positioned in the center of the internal wall surface of the operating chamber.
In this configuration, the fact that the opening of the supply/withdrawal passage is positioned in the center of the circular internal wall surface of the operating chamber allows the operating gas to be efficiently supplied to or withdrawn from the operating chamber.
In another preferred embodiment of the pump for supplying chemical liquids, the opening of the supply/withdrawal passage is positioned in the center of the internal wall surface of the operating chamber, with the internal wall formed symmetrically from its center; and the venting groove is formed to be symmetrical, with the center of the opening of the supply/withdrawal passage at its center, in correspondence with the internal wall surface of the operating chamber.
In this configuration, the venting groove is formed to be symmetrical from its center positioned at the center of the internal wall surface of the operating chamber, where the opening of the supply/withdrawal passage is positioned. Therefore, if, while a chemical liquid is being drawn in, the center of the diaphragm covers the opening of the supply/withdrawal passage first, this venting groove maintains the interior of the operating chamber at a stable negative pressure, enabling the diaphragm to stably deform.
In either of the above configurations, the venting groove should preferably have a linear shape.
Such a linear shape allows the venting groove to be easily formed.
The venting groove can also be configured from continuous concave areas obtained by forming a rough internal wall surface in the operating chamber.
Configuring the venting groove from continuous concave areas obtained by forming a rough internal wall surface in the operating chamber allows the venting groove to be easily formed by simply roughening the internal wall surface.
Note that the internal wall surface can be easily roughened by means of shot blasting, that is, by blasting the surface with abrasive grains.
Preferably, the entire internal wall surface of the operating chamber should be roughened.
According to this configuration, the roughening of the internal wall surface of the operating chamber is applied to the entire internal wall surface, which corresponds to the deformation region of the diaphragm. Thus, there is no need to separate the internal wall surface of the operating chamber into an area that should be roughened and an area that should not be roughened, thereby simplifying the operation of roughening the internal wall surface. Furthermore, the fact that the entire internal wall surface of the operating chamber is roughened prevents the diaphragm from blocking the venting groove until the diaphragm deforms sufficiently toward the operating chamber, thus ensuring reliable evacuation (drawing out) of the operating gas from the operating chamber.
In either of the above configurations, the pump housing should preferably be formed to be thin in the deformation direction of the diaphragm.
When the pump housing is formed to be thin in the deformation direction of the diaphragm, the operating chamber must also be formed to be thin in the same direction. Since the resulting structure tends to cause the center of the diaphragm to contact the internal wall surface of the operating chamber first during suctioning of a chemical liquid, the significance of providing the venting groove is great.

BRIEF EXPLANATION OF DRAWINGS

[FIG. 1] is a frontal cross-sectional diagram illustrating the pump unit inside the chemical liquid supply system.
[FIG. 2] (a) is a side cross-sectional diagram of the pump unit, and (b) is an enlarged cross-sectional diagram of (a).
[FIG. 3] is a circuit diagram illustrating the entire circuitry of the chemical liquid supply system.
[FIG. 4] (a) is the front view of the pump housing on the operating chamber side, and (b) is a cross-sectional diagram along line A-A in (a).
[FIG. 5] (a) and (b) are diagrams explaining the operation of the diaphragm.
[FIG. 6] (a) is the front view of the pump housing on the operating chamber side in another example, and (b) is a cross-sectional diagram along line B-B in (a).
[FIG. 7] (a) and (b) are diagrams explaining the operation of the diaphragm in another example.

EXPLANATION OF SYMBOLS

22 . . . pump housing; 22 b . . . supply/withdrawal passage; 22 c . . . internal wall surface; 22 d . . . opening; 22 e . . . venting groove; 22 f . . . venting groove; 22 g . . . concave area; 23 . . . diaphragm; 25 . . . pump chamber; 26 . . . operating chamber; R . . . resist liquid (chemical liquid).

DESCRIPTION OF THE PREFERRED EMBODIMENT

An embodiment in which the present invention is implemented into a pump unit of a chemical liquid supply system used in a manufacturing line of a semiconductor device, etc. is explained below, referencing the drawings. Note that FIG. 1 and FIG. 2 illustrate a pump unit 10, which is a primary component of the system, while FIG. 3 illustrates the entire chemical liquid supply system.
As shown in FIGS. 1 and 2, the pump unit 10 is formed by assembling together a pump 11, a solenoid switching valve 12, a suction-side shut-off valve 13, a discharge-side shut-off valve 14, a suckback valve 15, a regulator 16, a suction-side passage member 17 and a discharge-side passage member 18.
The pump 11 has a thin flat prism form having a nearly square shape when viewed from the front, and a pair of pump housings 21 and 22. Concave areas 21 a and 22 a, opened in almost circular dome shapes, are formed in the center of the opposing faces of pump housings 21 and 22, respectively. In the pump housings 21 and 22, the peripheries of the concave areas 21 a and 22 a hold and support a diaphragm 23 comprised of a circular flexible film made of a fluorine resin or the like, and the pump housings 21 and 22 are secured to each other using eight screws 24.
A diaphragm 23 partitions the space formed by the concave areas 21 a and 22 a of the pump housings 21 and 22, with the space on the side of pump housing 21 (the left side of the diaphragm 23 in FIG. 2) used as a pump chamber 25 and the space on the side of pump housing 22 (the right side of the diaphragm 23 in FIG. 2) used as an operating chamber 26. The pump chamber 25 is a space for supplying/withdrawing the resist liquid R (see FIG. 3) used as a chemical liquid, and the operating chamber 26 is a space for supplying/withdrawing the operation air for driving the diaphragm 23. Note that in order to reduce the thickness of the pump 11, the pump housings 21 and 22 are made thin (in this case in the deformation direction of the diaphragm 23), with the result that both the pump chamber 25 and the operating chamber 26 form thin spaces in the same direction.
A suction passage 21 b, which is connected to the pump chamber 25 and extends linearly downward, is formed in pump housing 21 on the pump chamber 25 side. The Suction passage 21 b is connected to suction passage 17 a of the suction-side passage member 17. A discharge passage 21 c, which is connected to the pump chamber 25 and extends linearly upward, is also formed in the pump housing 21. Furthermore, this discharge passage 21 c is provided on the same line L1 as the suction passage 21 b. Since the pump chamber 25 in this embodiment is formed as a thin space in the deformation direction of the diaphragm 23, the suction passage 21 b and discharge passage 21 c connected to this pump chamber 25 are bent perpendicularly near the pump chamber 25 to the degree necessary for connection (roughly equaling the width of the passage) (see FIG. 2). However, these bends do not significantly impact (create resistance to) the flow of the resist liquid R inside the pump 11, but allow the resist liquid R to flow smoothly in these areas.
A supply/withdrawal passage 22 b, which supplies operating air to the operating chamber 26, is formed in the pump housing 22 on the operating chamber 26 side. An opening 22 d of the supply/withdrawal passage 22 b on the internal wall surface 22 c of the operating chamber 26 (concave area 22 a) is positioned in the center of the circular concave area 22 a. Furthermore, as shown in FIG. 4, a cross-shaped venting groove 22 e, whose end extends to the periphery of the operating chamber 26, is formed on the internal wall surface 22 c of the operating chamber 26, and the opening 22 d of the supply/withdrawal passage 22 b is positioned in the intersection of the cross-shaped venting groove 22 e. This supply/withdrawal passage 22 b is then connected to a solenoid switching valve 12 secured to the pump housing 22.
Here, the intake port of the solenoid switching valve 12 is connected to one end of a supply tube 28 as shown in FIG. 3. The supply tube 28 has an electro-pneumatic regulator 27 in the middle, and the other end of the supply tube 28 is connected to a supply source 29 a. The electro-pneumatic regulator 27 is adjusted by a controller 50, such that the pressure of the operating air supplied from the supply source 29 a to the pump 11 remains constant at a preset value. The exhaust port of the solenoid switching valve 12 is connected to a vacuum generation source 29 b via an exhaust pipe 28 b. The solenoid switching valve 12 is controlled and switched by the controller 50 to connect the operating chamber 26 to either the supply source 29 a or the vacuum generation source 29 b. This switching action either supplies operating air to or withdraws it from the operating chamber 26, thereby switching the pump 11 between suctioning and discharging actions.
That is, when the action of the solenoid switching valve 12 supplies operating air to the operating chamber 26, the interior of the operating chamber 26 is pressurized, pushing the diaphragm 23 to the pump chamber 25 side and discharging the resist liquid R contained inside the pump chamber 25 to the downstream side via the discharge passage 21 c. In contrast, when the action of the solenoid switching valve 12 evacuates the operating air out of the operating chamber 26 and the pressure inside the operating chamber 26 becomes negative, the diaphragm 23, which has been pushed to the pump chamber 25 side, moves toward the operating chamber 26, introducing the resist liquid R from the upstream side into the pump chamber 25 via the suction passage 21 b.
Here, during suctioning of the resist liquid R, the diaphragm 23 deforms to its maximum deformation position to contact the internal wall surface 22 c of the operating chamber 26, as shown in FIG. 5 (a). During this deformation, the diaphragm 23 tends to deform at its center, as shown in FIG. 5 (b), such that its center may cover the opening 22 d of the supply/withdrawal passage 22 b before the diaphragm 23 deforms to its maximum deformation position. In this case, the opening 22 d is connected to the venting groove 22 e, which extends to the periphery of the operating chamber 26. Consequently, even when the diaphragm 23 deforms from the center, thus the center covers the opening 22 d of the supply/withdrawal passage 22 b first, the venting groove 22 e positioned on the outside of the contacted center is open. Therefore, it is possible to continue to evacuate the interior of the operating chamber 26 through the open venting groove 22 e (the arrow in FIG. 5 (b) indicates the flow of the operating air). As a result, even when such uneven deformation occurs in the diaphragm 23, the diaphragm 23 still reliably deforms to its maximum deformation position within a short period, thus shortening the time needed for filling the pump chamber 25 with the resist liquid R and ensuring a sufficient charging volume.
A rod-shaped, suction-side passage member 17 is secured to the center of the bottom of the pump housings 21 and 22. The suction-side passage member 17 is disposed along the flat direction of the pump 11. A suction passage 17 a, which extends nearly linearly downward, is formed in the suction-side passage member 17. This suction passage 17 a is disposed on the same line L1 as the suction passage 21 b of the pump 11. On the surface of the suction-side passage member 17 where it faces the pump housing 21, a concave housing section 17 b is formed around the suction passage 17 a, and the seal ring 33 is housed inside the concave housing section 17 b. The seal ring 33 is disposed between the suction-side passage member 17 and the pump housing 21, preventing the resist liquid R inside the suction passages 17 a and 21 b from leaking out of the gap between the suction-side passage member 17 and the pump housing 21.
The inner peripheral surface 33 a of the seal ring 33 is smoothly continuous with the inner peripheral surfaces of the suction passages 17 a and 21 b. Specifically, the seal ring 33 has a shape in which the inner peripheral surface 33 a is continuous with the inner peripheral surfaces of the suction passages 17 a and 21 b, and in which the concave area gradually deepens toward the outside in the radial direction as the distance from the internal passages 17 a or 21 b toward the center of the seal ring 33 in its thickness direction increases. In other words, this shape allows the resist liquid R to flow smoothly in the seal ring 33 area, preventing the resist liquid R and air bubbles from becoming trapped. Note that using an ordinary seal ring (O-ring) having a circular cross section creates an acute-angled dip between the seal ring and suction passages 17 a and 21 b. This results in a shape that is not smoothly continuous with the inner peripheral surfaces of the passages 17 a and 21 b, and causes the resist liquid R and air bubbles to problematically become trapped in this area. Additionally, as shown in FIG. 3, the suction-side passage member 17, using a coupling 19 provided at its tip, is connected to one end of a suction tube 31, while the other end of the suction tube 31 is guided into the resist liquid R contained inside a resist bottle 30.
The suction-side shut-off valve 13 consisting of an air-operated valve is assembled together with the suction-side passage member 17. The suction-side shut-off valve 13 has a nearly square prism shape, and is disposed in the direction perpendicular to the suction-side passage member 17 and along the flat direction of the pump 11 (pump housings 21 and 22). Here, as shown in FIG. 3, the suction-side shut-off valve 13 switches between opening and closing the suction passage 17 a based on the switching action of an electro-pneumatic regulator 32 that is controlled by the controller 50. That is, the suction-side shut-off valve 13 has the structure shown in FIG. 1. When its supply/withdrawal chamber 13 a is opened to the atmosphere by the switching action of the electro-pneumatic regulator 32, the valve body 13 b of the suction-side shut-off valve 13 receives a spring force from a spring 13 c and shuts off the suction passage 17 a; when operating air is supplied to the supply/withdrawal chamber 13 a from the supply source 29 a, the valve body 13 b sinks by working against the spring force of the spring 13 c to open the suction passage 17 a. Note that the part of the suction passage 17 a near the valve body 13 b is bent perpendicularly to the degree necessary for ensuring the reliable opening and closing action of the valve body 13 b (roughly equaling the width of the passage). However, this bend does not significantly impact (create resistance to) the flow of the resist liquid R inside the passage member 17, but allows the resist liquid R to flow smoothly in this area as well.
The rod-shaped, discharge-side passage member 18 is secured to the center of the top of the pump housings 21 and 22. The discharge-side passage member 18 is disposed along the flat direction of the pump 11. The discharge passage 18 a, which extends nearly linearly upward, is formed in the discharge-side passage member 18. This discharge passage 18 a is disposed on the same line L1 as the discharge passage 21 c of the pump 11. On the surface of the discharge-side passage member 18 where it faces the pump housing 21, a concave housing section 18 b is formed around the discharge passage 18 a, and a seal ring 34 is housed inside the concave housing section 18 b. The seal ring 34 is disposed between the discharge-side passage member 18 and the pump housing 21, preventing the resist liquid R inside the discharge passages 18 a and 21 c from leaking out of the gap between the discharge-side passage member 18 and the pump housing 21.
Like the aforementioned seal ring 33, the inner peripheral surface 34 a of the seal ring 34 is smoothly continuous with the inner peripheral surfaces of the discharge passages 18 a and 21 c, resulting in a structure that prevents the resist liquid R and air bubbles from becoming trapped. Additionally, as shown in FIG. 3, the discharge-side passage member 18, using a coupling 20 provided at its tip, is connected to one end of a discharge tube 35 having a nozzle 35 a on its other end. The nozzle 35 a is orientated downward and disposed in a position that allows it to drip the resist liquid R onto the center of a semiconductor wafer 37 that is placed on and spins with a spinning platform 36.
A discharge-side shut-off valve 14 consisting of an air-operated valve is assembled together with the discharge-side passage member 18. The discharge-side shut-off valve 14 has a nearly square prism shape, and is disposed in the direction perpendicular to the discharge-side passage member 18 and along the flat direction of the pump 11 (pump housings 21 and 22). Here, as shown in FIG. 3, the discharge-side shut-off valve 14 is constructed in the same way as the aforementioned suction-side shut-off valve 13 and switches between opening and closing the discharge passage 18 a based on the switching action of an electro-pneumatic regulator 38 that is controlled by the controller 50. That is, the discharge-side shut-off valve 14 has the structure shown in FIG. 1. When its supply/withdrawal chamber 14 a is opened to the atmosphere by the switching action of the electro-pneumatic regulator 38, a valve body 14 b of the discharge-side shut-off valve 14 receives a spring force from a spring 14 c and shuts off the discharge passage 18 a; when operating air is supplied to the supply/withdrawal chamber 14 a from the supply source 29 a, the valve body 14 b sinks by working against the spring force of the spring 14 c to open the discharge passage 18 a. Note that the part of the discharge passage 18 a near the valve body 14 b is bent perpendicularly to the degree necessary for ensuring the reliable opening and closing action of the valve body 14 b (roughly equaling the width of the passage). However, this bend does not significantly impact (create resistance to) the flow of the resist liquid R inside the passage member 18, but allows the resist liquid R to flow smoothly in this area as well.
The suckback valve 15 consisting of an air-operated valve is assembled together with the discharge-side passage member 18, next to and on the downstream side of the discharge-side shut-off valve 14. The suckback valve 15 also has a nearly square prism shape, and is disposed in the direction perpendicular to the discharge-side passage member 18 and along the flat direction of the pump 11 (pump housings 21 and 22). Here, as shown in FIG. 3, the suckback valve 15 is designed to suck back a predetermined amount of the resist liquid R located downstream of the valve 15 to the upstream side to prevent unintended dripping of the resist liquid R from the nozzle 35 a, based on the switching actions of an electro-pneumatic regulator 39. That is, the suckback valve 15 has the structure shown in FIG. 1. When its supply/withdrawal chamber 15 a is opened to the atmosphere by the switching action of the electro-pneumatic regulator 39, a valve body 15 b of the suckback valve 15 sinks by receiving a spring force from a spring 15 c and enlarges the volume of the volume-expansion chamber 18 c connected in communication with the discharge passage 18 a, sucking in the predetermined amount of the resist liquid R into the volume-expansion chamber 18 c. In contrast, when operating air is supplied to the supply/withdrawal chamber 15 a from the supply source 29, the valve body 15 b protrudes by working against the spring force of the spring 15 c, reducing the volume of the volume-expansion chamber 18 c provided in the discharge passage 18 a.
Furthermore, the regulator 16 having the shape of an approximate rectangular parallelepiped is secured to the discharge-side passage member 18 on the side opposite from the discharge-side shut-off valve 14 and the suckback valve 15. That is, the regulator 16 is installed on the discharge-side passage member 18 along the flat direction of the pump 11. A base 41 of the regulator 16 is secured to the discharge-side passage member 18. A securing platform 42 is secured to the base 41, and the electro- pneumatic regulators 38 and 39, which switch the discharge-side shut-off valve 14 and the suckback valve 15, are secured to the securing platform 42. A cover 43 that covers the electro- pneumatic regulators 38 and 39 is installed on this securing platform 42. Furthermore, communication passages 45 and 46, which are connected to the electro- pneumatic regulators 38 and 39, are respectively formed on the securing platform 42 and the base 41, and are respectively connected to the supply/withdrawal chambers 14 a of the discharge-side shut-off valve 14 and the supply/withdrawal chambers 15 a of the suckback valve 15, though not shown in the figure. Based on the control by the controller 50, the electro- pneumatic regulators 38 and 39 either supply operating air to or withdraw it from the supply/withdrawal chambers 14 a of the discharge-side shut-off valve 14 and the supply/withdrawal chambers 15 a of the suckback valve 15, thereby operating the discharge-side shut-off valve 14 and the suckback valve 15.
In the pump unit 10 thus configured, the suction passage 17 a inside the suction-side passage member 17, the suction passage 21 b and the discharge passage 21 c inside the pump 11, and the discharge passage 18 a of the discharge-side passage member 18, through all of which the resist liquid R passes, are all linear in shape and disposed on the same line L1. That is, the structure of this pump unit 10 allows the length of the resist liquid R passage to be short as much as possible, while nearly eliminating areas inside the resist liquid R passage where the resist liquid R or air bubbles could become trapped. The structure of the seal rings 33 and 34 also nearly eliminates areas where the resist liquid R or air bubbles could become trapped.
As shown in FIG. 3, the controller 50 controls a series of actions of the chemical liquid supply system, by controlling the electro-pneumatic regulator 27 to set the operating air supplied to the pump 11 at the predetermined pressure level, and also by controlling the solenoid switching valve 12, which switches and operates the pump 11; the electro-pneumatic regulator 32, which switches and operates the suction-side shut-off valve 13; and the electro- pneumatic regulators 38 and 39, which operate the discharge-side shut-off valve 14 and the suckback valve 15.
That is, when a command to begin the operation of the chemical liquid supply system is generated, the controller 50 first controls the electro-pneumatic regulator 32 to switch the suction-side shut-off valve 13, shutting off the suction passage 17 a. This action cuts the pump 11 off from the resist bottle 30. The controller 50 also switches the solenoid switching valve 12 to supply operating air adjusted to the predetermined pressure to the operating chamber 26 inside the pump 11. This action causes the diaphragm 23 to, move toward the pump chamber 25, pressurizing the resist liquid R contained inside the pump chamber 25. During this process, the discharge passage 18 a is shut off by the discharge-side shut-off valve 14 on the downstream side of the pump 11, preventing discharge of the resist liquid R.
Next, the controller 50 controls the electro-pneumatic regulator 38 to switch the discharge-side shut-off valve 14, opening the discharge passage 18 a, and also controls the electro-pneumatic regulator 39 to cancel the sucking-in of the resist liquid R by the suckback valve 15. During this process, the resist liquid R inside the pump chamber 25, pressurized by the diaphragm 23, is discharged from the pump 11, and a predetermined amount of this resist liquid R is dripped onto a semiconductor wafer from the nozzle 35 a at the tip of the discharge pipe 35 via the discharge passage 18 a.
Next, the controller 50 controls the electro-pneumatic regulator 38 to switch the discharge-side shut-off valve 14, shutting off the discharge passage 18 a. This action stops the discharge of the resist liquid R from the nozzle 35 a. The controller 50 also controls the electro-pneumatic regulator 39 to cause the suckback valve 15 to draw in a predetermined amount of the resist liquid R, preventing unintended dripping of the resist liquid R from the nozzle 35 a.
Next, the controller 50 controls the electro-pneumatic regulator 32 to switch the suction-side shut-off valve 13, opening the suction passage 17 a. This action connects the pump 11 to the resist bottle 30. The controller 50 also switches the solenoid switching valve 12, causing the operating air to be suctioned from the operating chamber 26 by means of the vacuum generation source 29 b. Then, the pressure inside the operating chamber 26 becomes negative, with the result that the diaphragm 23 deforms to its maximum deformation position to contact the internal wall surface 22 c of the operating chamber 26 and the resist liquid R is suctioned into and fills the pump chamber 25.
During this suctioning, if the center of the diaphragm 23 first covers the opening 22 d of the supply/withdrawal passage 22 b, the opening 22 d is connected to the venting groove 22 e, which extends to the periphery of the operating chamber 26, causing the evacuation of the interior of the operating chamber 26 to continue through the venting groove 22 e positioned on the outside of the center that is contacted first. Therefore, even when such uneven deformation occurs in the diaphragm 23, the diaphragm 23 can reliably deform to its maximum deformation position within a short period, thus shortening the time needed for filling the pump chamber 25 with the resist liquid R and ensuring a sufficient charging volume. From this point on, the controller 50 repeats the aforementioned actions such that a predetermined amount of resist liquid R is dripped onto each semiconductor wafer 37, as they are carried in one after another.
Next, the characteristic effects of such an embodiment are described.
In the present embodiment, the opening 22 d of the supply/withdrawal passage 22 b is positioned in the center of the internal wall surface 22 c of the operating chamber 26 (concave area 22 a), and the cross-shaped venting groove 22 e, which extends from the opening 22 d of the supply/withdrawal passage 22 b toward the periphery of the internal wall surface 22 c, is formed on the internal wall surface 22 c. During suctioning of the resist liquid R, the operating air the operating chamber 26 is evacuated through the supply/withdrawal passage 22 b. In this case, the diaphragm 23 tends to deform in its center, which may cover the opening 22 d of the supply/withdrawal passage 22 b first. However, in the present embodiment, the opening 22 d of the supply/withdrawal passage 22 b is connected to the venting groove 22 e, which opens toward the periphery of the operating chamber 26. Therefore, even when the diaphragm 23 deforms in this manner, the venting groove 22 e positioned on the outside of the contacted center is open, making it possible to continue to evacuate the operating air inside the operating chamber 26 through the open venting groove. As a result, even when such uneven deformation occurs in the diaphragm 23, the diaphragm 23 can reliably deform to its maximum deformation position toward the operating chamber 26 within a short period, thus shortening the time needed for filling the pump chamber 25 with the resist liquid R and ensuring a sufficient charging volume.
In the present embodiment, the fact that the opening 22 d of the supply/withdrawal passage 22 b is positioned in the center of the circular internal wall surface 22 c of the operating chamber 26 allows the operating air to be efficiently supplied to or withdrawn from the operating chamber 26.
In the present embodiment, since the venting groove 22 e extends to the periphery of the operating chamber 26, the diaphragm 23 can be prevented from blocking the venting groove 22 e until the diaphragm 23 deforms sufficiently toward the operating chamber 26, thus ensuring reliable evacuation of the operating air inside the operating chamber 26.
In the present embodiment, the venting groove 22 e is formed in a symmetric cross shape, with its center positioned at the center of the internal wall surface 22 c of the circular operating chamber 26 (concave area 22 a), which has a symmetric shape. Therefore, during suctioning of the resist liquid R, even if the center of the diaphragm 23 covers the opening 22 d of the supply/withdrawal passage 22 b first, the venting groove 22 e maintains the pressure inside the operating chamber 26 at a stable negative pressure, enabling the diaphragm 23 to stably deform.
In the present embodiment, the venting groove 22 e is designed to have a linear shape, which allows it to be easily formed.
In the present embodiment, since the pump housing 22 is formed to be thin in the deformation direction of the diaphragm 23 in order to make the pump 11 thin, the operating chamber 26 is also formed to be thin in the same direction. Because the resulting structure tends to cause the center of the diaphragm 23 to contact the internal wall surface 22 c of the operating chamber 26 first during suctioning of the resist liquid R, the significance of providing the venting groove 22 e is great.
Note that the present invention is not limited to the described contents of the aforementioned embodiment and may be implemented in other ways, as in the following examples.
In the aforementioned embodiment, the cross-shaped venting groove 22 e is formed on the internal wall surface 22 c of the operating chamber 26 (concave area 22 a). However, the shape of the venting groove is not limited to such a shape. Although the venting groove 22 e has a cross shape that extends in all four directions from the opening 22 d, it can also have a Y shape that extends in three directions, for example. The venting groove may also have a shape that extends in any other odd or even number of directions. Note that when changing the shape of the venting groove, it is desirable to position the venting groove as close as possible to the periphery of the operating chamber, and it is best to extend the venting groove to the periphery of the operating chamber 26 (concave area 22 a) as in the aforementioned embodiment.
Furthermore, as indicated by the dots in FIG. 6, it is also possible to form the entire internal wall surface 22 c of the operating chamber 26 as a rough surface, and configure a venting groove 22 f with continuous individual concave areas 22 g obtained by roughening the surface, as indicated by the dash line in FIG. 7 (b). With such a configuration, even when the center of the diaphragm 23 covers the opening 22 d of the supply/withdrawal passage 22 b first during suctioning of the resist liquid R as shown in FIG. 7 (a), the opening 22 d is connected to the venting groove 22 f, which extends to the periphery of the operating chamber 26 as the continuation of the concave areas 22 g. This allows the evacuation of the interior of the operating chamber 26 to continue through the venting groove 22 f, which is positioned on the outside of the contacted center. (In FIG. 7 (b), the arrow indicates the flow of the operating air.) Such a configuration also provides similar effects to those provided by the embodiment described above.
Note that the internal wall surface 22 c can be easily roughened by means of shot blasting, that is, by blasting the surface with abrasive grains. Moreover, since the entire internal wall surface 22 c is roughened, there is no need to mask an area of the internal wall surface 22 c that should not be roughened, thus simplifying the operation of roughening the internal wall surface 22 c.
In the aforementioned embodiment, the opening 22 d of the supply/withdrawal passage 22 b is positioned at the center of the operating chamber 26 (concave area 22 a), but it can also be offset from the center.
In the aforementioned embodiment, the pressure inside the operating chamber 26 is set to be negative during suctioning of the resist liquid R. However, the operating chamber 26 can also be opened to the surrounding atmosphere. In this case, the interior of the resist bottle 30, for example, must be pressurized.
In the aforementioned embodiment, the pump unit 10 is comprised of the pump 11, which acts as a pump for supplying chemical liquids and into which shut-off valves 13 and 14, the suckback valve 15, or the like are integrated. However, other configurations that have at least the pump 11 body can also be used.
In the aforementioned embodiment, an explanation is provided using operating air as an example. However, it is also possible to use another gas such as nitrogen in place of air.
In the aforementioned embodiment, an example using the resist liquid R is described. This is because the target onto which the chemical liquid is to be dripped is assumed to be a semiconductor wafer 37. However, other chemical liquids and other chemical liquid dripping targets may also be used.

Claims

1. In a pump for supplying chemical liquids in which a pump chamber and an operating chamber are divided by means of a diaphragm comprised of a flexible film, the diaphragm deforms toward the pump chamber when the interior of the pump chamber is pressurized using an operating gas, thereby discharging the chemical liquid that has been supplied into the pump chamber; and when the interior of the operating chamber reaches a negative pressure because of the withdrawal of the operating gas or when the interior of the operating chamber is opened to the surrounding atmosphere, the diaphragm deforms toward the operating chamber, thereby drawing a chemical liquid into the pump chamber, and a supply/withdrawal passage for supplying the operating gas to or withdrawing same from the operating chamber is formed in the pump housing, and an opening of the supply/withdrawal passage is provided in part of the internal wall surface of the operating chamber, and a venting groove that extends from the opening of the supply/withdrawal passage to the periphery of the internal wall surface is formed on the internal wall surface of the operating chamber.

2. The pump for supplying chemical liquids according to claim 1, wherein the internal wall surface of the operating chamber is circular in shape, and the opening of the supply/withdrawal passage is positioned in the center of the internal wall surface of the operating chamber.

3. The pump for supplying chemical liquids according to claim 1, wherein the opening of the supply/withdrawal passage is positioned in the center of the internal wall surface of the operating chamber with the internal wall formed symmetrically from its center; and

the venting groove is formed to be symmetrical, with the center of the opening of the supply/withdrawal passage at its center, in correspondence with the internal wall surface of the operating chamber.

4. The pump for supplying chemical liquids according to claim 1, wherein the venting groove is linear in shape.

5. The pump for supplying chemical liquids according to claim 1, wherein the venting groove is configured from continuous concave areas obtained by forming a rough internal wall surface in the operating chamber.

6. The pump for supplying chemical liquids according to any of claim 5, wherein roughening of the internal wall surface of the operating chamber is applied to the entire internal wall surface.

7. The pump for supplying chemical liquids according to claim 1, wherein the pump housing is formed to be thin in the deformation direction of the diaphragm.

8. The pump for supplying chemical liquids according to claim 2, wherein the venting groove is linear in shape.

9. The pump for supplying chemical liquids according to claim 2, wherein the venting groove is configured from continuous concave areas obtained by forming a rough internal wall surface in the operating chamber.

10. The pump for supplying chemical liquids according to claim 9, wherein roughening of the internal wall surface of the operating chamber is applied to the entire internal wall surface.