US20060137419A1

US20060137419A1 - Apparatus and method for supplying liquid and apparatus for processing substrate

Info

Publication number: US20060137419A1
Application number: US11/321,284
Authority: US
Inventors: Yasuhiro Mizohata
Original assignee: Dainippon Screen Manufacturing Co Ltd
Current assignee: Dainippon Screen Manufacturing Co Ltd
Priority date: 2004-12-27
Filing date: 2005-12-23
Publication date: 2006-06-29
Also published as: JP2006184989A; US20060248934A9; JP4437744B2

Abstract

A liquid supply apparatus comprises a pump mechanism for pumping out a liquid to a conduit, a flowmeter for measuring a flowrate of the liquid flowing through the conduit, and a controller for controlling these mechanisms. The pump mechanism comprises a flexible chamber made of resin, a pressure chamber housing the flexible chamber, and an electro-pneumatic regulator for adjusting pressure in a space between the pressure chamber and the flexible chamber. The flexible chamber comprises a bellows. In the liquid supply apparatus, while pressure is applied to the flexible chamber of the pump mechanism and the liquid in the flexible chamber is pumped out to the conduit, the pressure applied to the flexible chamber is controlled by the controller on the basis of a flowrate of the liquid measured by the flowmeter. This makes it possible to supply the liquid of a small flowrate while controlling the flowrate accurately.

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention
The present invention relates to an apparatus and a method for supplying a liquid and preferably, an apparatus for supplying a liquid is used for an apparatus for processing a substrate.
2. Description of the Background Art
Conventionally, in cleaning a semiconductor substrate (hereinafter, referred to as simply “substrate”), well known a technique where a dilute hydrochloric acid (HCl) is used instead of a pure water as a cleaning liquid, whereby preventing fine particles in the cleaning liquid from adhering to a surface of the substrate by a Coulomb force. Also, etching of a substrate is performed by using a dilute hydrofluoric acid (HF) or final cleaning of the substrate is performed by using a dilute acid solution (hydrochloric acid, hydrofluoric acid or the like).
A cleaning apparatus of a substrate uses a solution which is obtained by diluting a stock solution of the hydrochloric acid at less than or equal to 1/1000. For simplification or miniaturization or the like of a construction of an apparatus, diluted solution is normally produced by a method (i.e., the so-called direct mixing method) in which a small amount of an undiluted solution of hydrochloric acid is directly injected into a tube for pure water of the cleaning apparatus. In the cleaning apparatus, a flowrate of the hydrochloric acid injected into the pure water is measured by a flowmeter and by controlling the flowrate of the hydrochloric acid on the basis of an output from the flowmeter, the diluted solution is set at the desired concentration.
In the above case, U.S. Pat. No. 5,672,832 (Document 1) and U.S. Pat. No. 6,578,435 (Document 2) disclose a differential pressure flowmeter for measuring a flowrate by measuring a pressure difference in the front and back of a nozzle disposed within a conduit. Japanese Patent Application Laid Open Gazette No. 2004-226142 (Document 3) and Japanese Patent Application Laid Open Gazette No. 2004-226144 (Document 4) disclose a differential pressure flowmeter where by measuring a pressure difference in both ends of a capillary, measurement of a very small flowrate is performed stably.
Japanese Patent Application Laid Open Gazette No. 11-94608 (Document 5) discloses a technique for improving the measuring accuracy of a flowrate in a flowmeter including a float which moves up and down according to a flowrate of a fluid in a pipe thereof. Rod-shaped elements project upward and downward from the float, and a magnet is placed in the pipe surrounding the float and the rod-shaped elements, whereby the float is kept on a center axis of the pipe, and slight vibration is prevented. The document 5 also discloses a technique for adjusting a supply rate of chemicals in a substrate processing apparatus comprising this flowmeter, where a pneumatic valve positioned in a supply pipe of chemicals is controlled on the basis of an output from the flowmeter.
In producing the diluted solution, an extremely small amount of undiluted solution needs to be injected into the pure water with high accuracy. For example, in a batch-type cleaning apparatus, a flowrate of the undiluted solution is normally less than or equal to 100 ml/min, this very small flowrate needs to be measured high accurately and controlled. In a single wafer-type cleaning apparatus, a flowrate of a stock (or undiluted) solution is set to be less than or equal to 10 ml/min.
Since the differential pressure flowmeters of Documents 1 and 2 make turbulent flow in the vicinity of the nozzle to measure a flowrate, they are not suitable for measurement of a very small flowrate having a high possibility of a laminar flow. In some liquid mass flowmeters for measuring a very small flowrate, the inside of the flowmeter is covered with resin for increasing durability against chemicals, however, it is needed for the inside of the flowmeter to be covered with thick resin for durability against a hydrofluoric acid or the like, and it is difficult to measure a flowrate accurately by these flowmeters.
In the differential pressure flowmeters of Documents 3 and 4, a long capillary is used as a pressure loss part and assuming that a flow of a liquid in the capillary is laminar, a flowrate is obtained on the basis of an equation with respect to pressure loss in the laminar flow in a round tube. However, in the case where the flow is transitional or turbulent, the measuring accuracy of a flowrate decreases, and thus it is important to make a stable laminar flow. Also, since the flowrate is obtained by using the above equation concerning a straight round tube in spite of using the capillary having a bending part actually, it increases errors of measured flowrate.
In the substrate processing apparatus of Document 5, by controlling the pneumatic valve disposed within the supply pipe of the chemicals, a valve opening (i.e., a degree of a restriction of the supply pipe) changes to adjust the flowrate of the chemicals. It is therefore possible to supply the chemicals with sufficient accuracy in supply of a large flowrate, but there is a limit for improving the accuracy of a supply amount in supply of a small flowrate. In a conduit through which high-concentration hydrofluoric acid or hydrochloric acid flows, normally, a region of a valve exposed to a liquid for adjusting a flowrate such as a pneumatic valve or the like is made of fluorocarbon resin. The fluorocarbon resin has a low machining accuracy in comparison with metal or the like and it tends to change by an external force or surrounding temperature. Since a valve for adjusting a flowrate is needed to adjust a very small cross section of a very small conduit accurately, it is difficult to form this valve by such material with low shape stability.
On the other hand, when a liquid of a small flowrate is pumped out, for example, by an air cylinder without the valve such as the pneumatic valve or the like for adjusting a flowrate, the piston of the air cylinder needs to move at a very low speed. In this case, since a frictional resistance between the cylinder and the piston changes repeatedly between a static friction and a sliding friction, the piston vibrates or the air cylinder moves at a higher speed than a predetermined speed repeatedly after the piston is stopped. This phenomenon is called chattering or jerking and makes the accuracy of the supply amount low. In a case where the air cylinder is driven while preventing chattering or the like, it is difficult to keep the moving speed of the piston 1 mm/sec or less.

SUMMARY OF THE INVENTION

The present invention is intended for a liquid supply apparatus for supplying a liquid. The liquid supply apparatus comprises a pump mechanism for pumping out a liquid to a conduit by applying pressure to a flexible chamber to reduce a volume of the flexible chamber, a flowmeter placed in a downstream side of the pump mechanism for measuring a flowrate of the liquid flowing through the conduit, and a controller for sending an electrical signal to the pump mechanism, the electrical signal controlling pressure applied to the flexible chamber so that the flowrate of the liquid flowing through the conduit is adjusted to a predetermined flowrate on the basis of a flowrate of the liquid obtained by the flowmeter. According to the liquid supply apparatus in accordance with the present invention, it is possible to supply the liquid of a small flowrate while controlling the flowrate accurately.
According to one preferred embodiment of the present invention, since the flexible chamber is made of resin, it is possible to supply various kinds of liquid. According to another preferred embodiment of the present invention, since the flexible chamber comprises a bellows, it is possible to change a volume of the flexible chamber easily and suppress deterioration of the flexible chamber.
According to still another preferred embodiment of the present invention, the pump mechanism comprises a pressure chamber housing the flexible chamber, and an electro-pneumatic regulator for adjusting pressure in a space between the pressure chamber and the flexible chamber. This makes it possible to control the pressure in the space between the pressure chamber and the flexible chamber with high response and high accuracy.
According to an aspect of the present invention, the liquid supply apparatus further comprises the other pump mechanism which has the same constituents as the pump mechanism, and in the apparatus, compression of one chamber of the flexible chamber of the pump mechanism and the other flexible chamber of the other pump mechanism and concurrent expansion of the other chamber of the flexible chamber and the other flexible chamber are performed alternately to the flexible chamber and the other flexible chamber by control of the controller. This makes it possible to supply the liquid of a small flowrate long hours continuously while controlling the flowrate accurately.
According to another aspect of the present invention, the flowmeter is a differential pressure flowmeter, and the differential pressure flowmeter comprises a round tube provided as a part of the conduit in which a flow of the liquid with a Reynolds number less than or equal to 2000 is formed, a first pressure sensor placed between the pump mechanism and the round tube for measuring a pressure of the liquid flowing into the round tube, and a second pressure sensor placed in a downstream side of the round tube for measuring a pressure of the liquid flowing out of the round tube. This makes it possible to measure the flowrate with high accuracy stably.
The present invention is also intended for a method for supplying a liquid and also intended for a substrate processing apparatus comprising the liquid supply apparatus.
These and other objects, features, aspects and advantages of the present invention will become more apparent from the following detailed description of the present invention when taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a view illustrating a construction of a liquid supply apparatus in accordance with a first preferred embodiment;
FIG. 2 and FIG. 3 are enlarged views illustrating the vicinity of a flexible chamber and a pressure chamber;
FIG. 4 and FIG. 5 are a front view and a plan view illustrating a construction of a flowmeter;
FIG. 6 is a graph illustrating a relation between a pressure difference and a flowrate;
FIG. 7 is a view illustrating an operation flow of the liquid supply apparatus for supplying a liquid;
FIG. 8 is a view illustrating an operation flow of the liquid supply apparatus for controlling a flowrate;
FIG. 9 is a view illustrating a pump mechanism of a comparative example;
FIG. 10 is a view illustrating a construction of a liquid supply apparatus in accordance with a second preferred embodiment;
FIG. 11 and FIG. 12 are views illustrating an operation flow of the liquid supply apparatus for supplying a liquid;
FIG. 13 is a view illustrating a state of switching between a first pump mechanism and a second pump mechanism;
FIG. 14 is a view illustrating an operation flow of the liquid supply apparatus for controlling a flowrate;
FIG. 15 is a view illustrating a change of a flowrate;
FIG. 16 is a view illustrating a pump mechanism of a liquid supply apparatus in accordance with a third preferred embodiment; and
FIG. 17 and FIG. 18 are views illustrating substrate processing apparatuses in accordance with fourth and fifth preferred embodiments.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 is a view illustrating a construction of a liquid supply apparatus 1 in accordance with the first preferred embodiment of the present invention. The liquid supply apparatus 1 comprises a conduit 11 through which a liquid flows, a liquid supply source 12 connected to an upstream side of the conduit 11 for storing the liquid, a pump mechanism 13 placed in a downstream side of the liquid supply source 12 for storing the liquid supplied from the liquid supply source 12 to pump out the liquid to a downstream side of the conduit 11, a differential pressure flowmeter 14 placed in a downstream side of the pump mechanism 13 for measuring a flowrate of the liquid flowing through the conduit 11 (i.e., an amount of the liquid flowing through the conduit 11 per unit time), and a controller 15 for controlling these mechanisms. On the conduit 11, a first filter 111 and a first check valve 112 are installed between the liquid supply source 12 and the pump mechanism 13, a second check valve 113 is installed between the pump mechanism 13 and the flowmeter 14, and a pressure control tube 147 and a second filter 114 are installed on a downstream side of the flowmeter 14. In FIG. 1, hatching of cross sections are omitted.
The liquid supply source 12 is a bottle, a region exposed to the liquid of the bottle is covered with fluorocarbon resin (for example, PTFE (poly-tetra-fluoro-ethylene)), and the top of the bottle is open to the atmosphere. Stock solution such as hydrochloric acid, hydrofluoric acid, or the like is stored in the liquid supply source 12 and the stock solution is supplied to the pump mechanism 13 through the conduit 11. The first filter 111 is made of PTFE, for example and removes impurities such as particles and the like from the liquid which is supplied to the pump mechanism 13. The second filter 114 is also made of the fluorocarbon resin such as PTFE or the like and has a mesh of 0.05 μm, for example. In the liquid supply apparatus 1, the second filter 114 removes impurities from the liquid which is supplied from the liquid supply apparatus 1 to other apparatus and the like.
The whole of the first check valve 112 and the second check valve 113 are made of PFA (per-fluoro-alkoxy), for example and the first check valve 112 and the second check valve 113 prevent the liquid from flowing back from a downstream side to an upstream side of each check valve. Each of the first check valve 112 and the second check valve 113 may have constituents where a sapphire ball and a sapphire valve seat are provided in its outer casing made of the fluorocarbon resin.
The region exposed to the liquid of the liquid supply source 12, the first filter 111, the second filter 114, the first check valve 112, and the second check valve 113 are made of the fluorocarbon resin or the like, and thus they have high durability (mainly, corrosion resistance) against various kinds of liquid. The pressure control tube 147 will be discussed later together with the detailed description of the flowmeter 14.
The pump mechanism 13 comprises a flexible chamber 131 which is flexible and made of resin, an approximately cylindrical shaped pressure chamber 132 housing the flexible chamber 131 having an approximately cylindrical shape, and an electro-pneumatic regulator 133 and an ejector 134 for supplying or discharging air to/from the pressure chamber 132 to adjust pressure in a space between the pressure chamber 132 and the flexible chamber 131. The flexible chamber 131 is connected to the conduit 11 between the first check valve 112 and the second check valve 113. The electro-pneumatic regulator 133 and the ejector 134 are respectively connected to the pressure chamber 132 through pneumatic valves 1331, 1341.
The flexible chamber 131 comprises a bellows 1311 as a part thereof. Materials, such as PTFE, PFA, PEEK (poly-ether-ether-ketone), PCTFE (poly-chloro-trifluoro-ethylene), ETFE (ethylene-tetrafluoro-ethylene), FEP (fluorinated-ethylene-propylene) or the like, are available for the flexible chamber 131. A material for the flexible chamber 131 is determined on the basis of various kinds of liquid to be pumped out. In the preferred embodiment, the flexible chamber 131 is made of PFA or the like such as fluorocarbon resin. Since the pressure chamber 132 is not, normally, exposed to the liquid stored in the flexible chamber 131, the pressure chamber 132 may be made of vinyl chloride or the like which has slightly lower durability against liquid than the flexible chamber 131.
The electro-pneumatic regulator 133 comprises an air inlet connected to an external compressor for applying pressure, an air outlet for pressure-relief, and an outlet connected into the pressure chamber 132 for adjusting the pressure in the space between the pressure chamber 132 and the flexible chamber 131. The electro-pneumatic regulator 133 controls the pressure in the space between the pressure chamber 132 and the flexible chamber 131 steplessly and continuously to be a directed pressure on the basis of an electrical signal (i.e., in proportion to an input current or the like) sent from a feedback controller 151 of the controller 15. When the electro-pneumatic regulator 133 controls the pressure in the pressure chamber 132, the pneumatic valve 1331 is opened by an electromagnetic valve 1332 which is driven by a sequence controller 152 of the controller 15.
The ejector 134 is connected to the external compressor through a regulator 1343 and a pneumatic valve 1344. When the ejector 134 discharges air in the pressure chamber 132, pneumatic valves 1341, 1344 are opened by electromagnetic valves 1342, 1345 driven by the sequence controller 152, air supplied from the external compressor flows out of the ejector 134 at high speed, and then air in the pressure chamber 132 is discharged through the ejector 134. In the pump mechanism 13, the electromagnetic valves may be used instead of the pneumatic valves 1331, 1341, 1344.
FIG. 2 and FIG. 3 are enlarged views illustrating the vicinity of the flexible chamber 131 and the pressure chamber 132 of the pump mechanism 13. FIG. 2 and FIG. 3 respectively illustrate states where the flexible chamber 131 is expanded and compressed. In the pump mechanism 13, an upper end 1312 of the flexible chamber 131 having the bellows 1311 is fixed to the pressure chamber 132 and an lower end 1313 is made free.
In the pump mechanism 13, the electro-pneumatic regulator 133 (see FIG. 1) supplies air from the bottom of the pressure chamber 132 (i.e., a part opposed to the lower end 1313 of the flexible chamber 131) into the pressure chamber 132, pressure is applied to the flexible chamber 131, and then the flexible chamber 131 in the state shown in FIG. 2 (hereinafter, referred to as “expanded state”) is compressed and gradually changes to the state shown in FIG. 3 (hereinafter, referred to as “compressed state”). With this operation, the liquid stored in the flexible chamber 131 is pumped out to the conduit 11 by applying pressure to the flexible chamber 131 to reduce a (internal) volume of the flexible chamber 131. The check valve 112 prevents the liquid pumped out of the flexible chamber 131 from flowing into the liquid supply source 12 (i.e., the upstream side) and the liquid flows to the flowmeter 14 (i.e., the downstream side) through the check valve 113.
In the pump mechanism 13, the ejector 134 (see FIG. 1) discharges air from the bottom of the pressure chamber 132, the pressure in the pressure chamber 132 changes to be negative, and then the flexible chamber 131 changes gradually from the compressed state shown in FIG. 3 to the expanded state shown in FIG. 2. With this operation, by expanding the flexible chamber 131 to increase a volume of the flexible chamber 131, the liquid is sucked from the liquid supply source 12 through the conduit 11 and the check valve 112, the sucked liquid flows into the flexible chamber 131, and it is stored in the flexible chamber 131. At this time, the check valve 113 prevents suction of the liquid from the downstream side of the pump mechanism 13.
In the pump mechanism 13, a volume of a space between the flexible chamber 131 and the pressure chamber 132, that is to say, a volume of a space where pressure is controlled by the electro-pneumatic regulator 133, is made small, and this improves response of transition between suction of the liquid from the liquid supply source 12 to the flexible chamber 131 and pumping out of the liquid from the flexible chamber 131.
As shown in FIG. 2 and FIG. 3, the pump mechanism 13 further comprises a displacement sensor 135 for detecting a displacement of the lower end 1313 which is a free end of the flexible chamber 131 with respect to the pressure chamber 132, and a leakage sensor 136 for detecting a leakage, if there is a leakage of the liquid from the flexible chamber 131.
The displacement sensor 135 comprises two pairs of light emitting parts 1351 and light receiving parts 1352 on a side wall of the pressure chamber 132 (i.e., inner surface parallel to a direction of expansion and compression of the bellows 1311). Each pair of the light emitting parts 1351 and the light receiving parts 1352 is positioned in the both sides of the flexible chamber 131 in the expanded state shown in FIG. 2. Location of one pair with respect to the direction of expansion and compression of the flexible chamber 131 is almost same as the location of the lower end 1313 of the flexible chamber 131 in the expanded state, and location of the other pair is slightly lower than the location of the lower end 1313 of the flexible chamber 131 in the compressed state shown in FIG. 3.
In the pump mechanism 13, when the flexible chamber 131 is in the expanded state shown in FIG. 2, the flexible chamber 131 blocks lights from the two light emitting parts 1351, the displacement sensor 135 determines the flexible chamber 131 is in the expanded state. When the flexible chamber 131 is in the compressed state shown in FIG. 3, lights from the two light emitting parts 1351 pass through the inner space of the pressure chamber 132, the light receiving parts 1352 receive the lights, and then the displacement sensor 135 determines the flexible chamber 131 is in the compressed state. In a case where a light from one light emitting part 1351 which is located near the bottom of the pressure chamber 132 is received by the opposed light receiving part 1352 and a light from the other light emitting part 1351 does not reach the light receiving part 1352, the displacement sensor 135 determines the flexible chamber 131 is in an intermediate state between the state of FIG. 2 and that of FIG. 3.
The leakage sensor 136 comprises a pair of electrodes 1361, and the pair of electrodes 1361 is positioned in the bottom of grooves 1321 located on an inner side of the bottom of the pressure chamber 132. In the pump mechanism 13, in a case where the liquid leaks from the flexible chamber 131, the leaked liquid collects in the grooves 1321 at the bottom of the pressure chamber 132, and the pair of electrodes 1361 is electrically connected each other through the liquid (electrolyte solution) in the grooves 1321. The leakage sensor 136 detects conduction between the pair of electrodes 1361 to detect the leakage of the liquid from the flexible chamber 131.
FIG. 4 and FIG. 5 are a front view and a plan view illustrating a construction of the flowmeter 14, respectively. As shown in FIG. 4 and FIG. 5, the flowmeter 14 comprises a tube 143 provided as a part of the conduit 11 (see FIG. 1) and which is a pressure loss part having a circular section (i.e., round tube), a tube base 144 to which the tube 143 is attached, a first pressure sensor 141 placed between the pump mechanism 13 (see FIG. 1) and the tube 143 (in the left of FIG. 4 and FIG. 5) for measuring a pressure of the liquid flowing into the tube 143 and a second pressure sensor 142 placed in a downstream side of the tube 143 for measuring a pressure of the liquid flowing out of the tube 143. As shown in FIG. 4, the flowmeter 14 further comprises a storage part 145 for storing information and an operation part 146 for performing various computations.
The tube 143 is made of resin and has high durability (mainly, corrosion resistance) against various kinds of liquid. The tube 143 has flexibility and is formed in a coil above the tube base 144 as shown in FIG. 4. Materials, such as PEEK, PTFE, PCTFE, PFA, ETFE, FEP, or the like, are available for the tube 143. A material for the tube 143 is determined on the basis of various kinds of liquid to be measured, an inner diameter of the tube 143, or the like. In the first preferred embodiment, the tube 143 is made of PFA.
The inner diameter of the tube 143 is determined on the basis of the maximum value of a measured flowrate of the flowmeter 14 such that a Reynolds number of a flow of the liquid within the tube 143 is made at less than or equal to 2000. The Reynolds number is the dimensionless number indicating the type of a flow (i.e., a flow is laminar or turbulent). When a Reynolds number of a flow is smaller than a critical Reynolds number (about 2000 to 2300), the flow is kept laminar. A Reynolds number Re within the tube 143 having a circular section is expressed as Eq. 1 where D (m) is the inner diameter of the tube 143.
Re=ρUD/μ=4 ρQ/πμD Eq. 1
In Eq. 1, ρ is density (kg/m³) of the liquid flowing through the tube 143, μ is coefficient of viscosity (N·s/m²) of the liquid, U is average flowing velocity (m/s) of the liquid in a cross-sectional area vertical to a longitudinal direction of the tube 143, and Q is a flowrate (m³/s) of the liquid.
In the flowmeter 14, the maximum value of a Reynolds number within a measuring range (i.e., a Reynolds number at the maximum of the measured flowrate) is set to be less than or equal to 2000 and laminar flow occurs within the tube 143. For this reason, an inlet length X(m) necessary for full development of the flow of the liquid (i.e., velocity distribution of the flow within the cross-sectional area of the tube 143 goes into a constant state) is expressed as Eq. 2 for the Boussinesq equation by using the Reynolds number Re and the inner diameter D(m) of the tube 143.
X≧0.065 Re·D Eq. 2
The length of the tube 143 is preferably set to be 130 or more times than the inner diameter of the tube 143 so that the length of which becomes longer than the inlet length even if the Reynolds Number is 2000. The length of the tube 143 is determined on the basis of a pressure loss required in the tube 143 (i.e., a pressure difference between both ends of the tube 143), and an outer diameter of the tube 143 is set to be 1.5 or more times larger than the inner diameter so as to ensure mechanical strength of the tube 143 of resin.
The tube base 144 is a block of resin (made of PTFE which is the fluorocarbon resin, for example) and has two L-shaped channels therein. As shown in FIG. 4, both ends of the tube 143 are detachably attached at the top of the tube base 144 through tube fittings of resin. As the tube fittings, various small diameter fittings for liquid chromatography or the like can be used. The inside channels of the tube base 144, the tube 143, inside channels of the first pressure sensor 141 and the second pressure sensor 142 (later discussed), and pressure transducers 1411, 1421 are also provided as parts of the conduit 11 of the liquid supply apparatus 1.
As shown in FIG. 4 and FIG. 5, the first pressure sensor 141 and the second pressure sensor 142 comprise approximately cylindrical pressure transducers 1411, 1421, and the pressure transducers 1411, 1421 are easy to exhaust air while injecting the liquid because their heights are low. As shown in FIG. 4, members 1412, 1422 which are positioned in the pressure transducers 1411, 1421 and exposed to the liquid are made of resin (PTFE which is fluorocarbon resin, for example). In the first pressure sensor 141 and the second pressure sensor 142, the inside channels and the pressure transducers 1411, 1421 are connected directly and therefore this prevents accumulation of the liquid. Both ends of the inside channels of the first pressure sensor 141 and the second pressure sensor 142 have fittings which allow easy connection. In the first preferred embodiment, the first pressure sensor 141 and the second pressure sensor 142 have a measuring range from 0 to 0.2 Mpa (megapascal).
In the flowmeter 14, the liquid flows into the first pressure sensor 141 from the upstream side continuously, the liquid passes through the first pressure sensor 141, the tube base 144, the tube 143, and the second pressure sensor 142 sequentially, and then flows out to the downstream side. While the liquid is passing through the flowmeter 14, a flowrate of the liquid is measured continuously. Next discussion will be made on an operation flow of the flowmeter 14 for measuring a flowrate of the liquid.
While the liquid is flowing through the flowmeter 14, a pressure of the liquid flowing into the tube 143 is measured by the first pressure sensor 141 and a pressure of the liquid flowing out of the tube 143 is measured by the second pressure sensor 142. Outputs from the first pressure sensor 141 and the second pressure sensor 142 (for example, the outputs are values of pressures to be measured which are converted to electrical signals ranging from 4 to 20 mA (milliampere) by both the pressure sensors) are transmitted to a subtracter 1461 of an operation part 146, the output of the second pressure sensor 142 is subtracted from the output of the first pressure sensor 141 in the subtracter 1461, and then a pressure difference between both ends of the tube 143 is obtained.
FIG. 6 is a graph illustrating a relation (hereinafter referred to as “flowrate information”) between the pressure difference between both ends of the tube 143 and the flowrate of the liquid flowing through the tube 143. As shown in FIG. 6, the pressure difference and the flowrate have an approximately proportionality relation in the flowmeter 14. Since the flow within the tube 143 is laminar where the Reynolds number is less than or equal to 2000, the pressure difference and the flowrate should be directly proportioned theoretically. The reason why the pressure difference and the flowrate are not perfectly proportioned is considered as an effect of the flow in the vicinity of both ends of the tube 143, a state of an inside surface of the tube 143, and the like.
Before the flowmeter 14 is actually installed in the liquid supply apparatus 1, the flowrate information is obtained by the following method in advance. A syringe pump is attached to the upstream side of the first pressure sensor 141 and the liquid (preferably, the pure water) is injected at a constant ejection rate. The injected liquid passes through the first pressure sensor 141, the tube base 144, the tube 143, and the second pressure sensor 142, and flows out of the flowmeter 14. In the first pressure sensor 141 and the second pressure sensor 142, pressures in passing of the liquid are measured and a pressure difference is obtained. After the passage of a predetermined time, a weight of the liquid flowing out of the flowmeter 14 is measured and a flowrate corresponding to the pressure difference is obtained. Then, by changing the ejection rate of the syringe pump and repeating measurement of the pressure difference and the flowrate, the flowrate information shown in FIG. 6 is obtained. This obtained flowrate information is stored in the storage part 145 before actual use of the flowmeter 14.
In the flowmeter 14 shown in FIG. 4, the pressure difference between both ends of the tube 143 obtained by the subtracter 1461 is transmitted to a linearizer 1462 as an electrical signal ranging from 0 to 5V, for example, and the flowrate information stored in the storage part 145 in advance is read out by the linearizer 1462. In the linearizer 1462, a flowrate of the liquid flowing through the tube 143 is determined automatically on the basis of the pressure difference and the flowrate information. The flowrate information stored in the storage part 145 may be a tabular form or an approximation formula, for example.
Referring back to FIG. 1, the discussed pressure control tube 147 is installed between the flowmeter 14 and the second filter 114. The pressure control tube 147 is made of resin with high durability against various kinds of liquid. The pressure control tube 147 also has flexibility and is formed in a coil.
In the liquid supply apparatus 1, since the liquid passes through the pressure control tube 147 before the liquid flowing out of the flowmeter 14 is supplied to another apparatus or the like through the second filter 114, pressure of the liquid becomes relatively low. For this reason, even if a required pressure in supplying the liquid from the liquid supply apparatus 1 is almost equal to an atmospheric pressure, it can be avoided that a pressure to be measured (i.e., a pressure difference between a pressure of the liquid and an atmospheric pressure) in the second pressure sensor 142 of the flowmeter 14 nears to 0 where the measuring accuracy becomes low. This improves the measuring accuracy of a flowrate by the flowmeter 14. From the viewpoint of improving the measuring accuracy of the flowrate, it is preferable that the length of the pressure control tube 147 is determined so that the minimum value of a pressure measured by the second pressure sensor 142 falls in a range 10% or more (in the preferred embodiment, the range is 20 kPa or more) from the bottom of the measuring range of the second pressure sensor 142, for example.
Next discussion will be made on an operation flow of the liquid supply apparatus 1 for supplying the liquid referring to FIG. 7. When the liquid is supplied by the liquid supply apparatus 1, a user fills the pump mechanism 13 and the conduit 11 with liquid for preparation. In the liquid filling, an end of the downstream side of the conduit 11 is connected to a drain.
The sequence controller 152 of the controller 15 shown in FIG. 1 closes the pneumatic valve 1331 of the pump mechanism 13 and opens the pneumatic valves 1341, 1344. The ejector 134 discharges air between the flexible chamber 131 and the pressure chamber 132, and then pressure reduction in the pressure chamber 132 is started. By this, the flexible chamber 131 which is in the compressed state (see FIG. 3) in advance is expanded, and the liquid is sucked from the liquid supply source 12 to be supplied to the flexible chamber 131 and stored therein. The displacement sensor 135 (see FIG. 2) detects that the flexible chamber 131 changed to the expanded state (see FIG. 2), and the pneumatic valves 1341, 1344 are closed to complete liquid supply to the flexible chamber 131 (Step S11). In the preferred embodiment, an amount of the liquid supplied to the flexible chamber 131 in one expansion is 30 ml and a volume of the flexible chamber 131 in the expanded state is 100 ml.
Subsequently, the user confirms whether or not air remains in the flexible chamber 131 and the conduit 11 (Step S12). In a case where air remains, the sequence controller 152 opens the pneumatic valve 1331, and the electro-pneumatic regulator 133 starts supplying air between the flexible chamber 131 and the pressure chamber 132 to increase the pressure in the pressure chamber 132 (i.e., pressure around the flexible chamber 131). The flexible chamber 131 is compressed by the increase of the pressure, and air remaining in the flexible chamber 131 and the conduit 11 is discharged from the downstream side of the conduit 11 to the outside of the liquid supply apparatus 1.
After the displacement sensor 135 detects the flexible chamber 131 changed to the compressed state, the pneumatic valve 1331 is closed and discharge of air in the flexible chamber 131 and the conduit 11 is stopped (Step S121), and liquid supply to the flexible chamber 131 is restarted back to Step S11. In the liquid supply apparatus 1, liquid supply to the flexible chamber 131 and discharge of air from the flexible chamber 131 and the conduit 11 (Steps S11 to S121) are repeated until air in the flexible chamber 131 and the conduit 11 is completely discharged and the liquid filling is finished.
After air in the flexible chamber 131 and the conduit 11 is completely discharged (Step S12), the end of the downstream side of the conduit 11 is connected to an external apparatus or the like to be supplied. Like in Step S121, the electro-pneumatic regulator 133 supplies air to the pressure chamber 132 to apply pressure to the flexible chamber 131, and the flexible chamber 131 in the expanded state is compressed. The liquid stored in the flexible chamber 131 is pumped out to the conduit 11 and supplied to the external apparatus or the like (Step S13). In the liquid supply apparatus 1, while the pump mechanism 13 is pumping out the liquid from the flexible chamber 131, a flowrate control shown in FIG. 8 is continuously performed. Next discussion will be made on an operation flow of the liquid supply apparatus 1 for controlling a flowrate.
In the liquid supply apparatus 1, when pumping out of the liquid from the pump mechanism 13 to the conduit 11 is started, a flowrate of the liquid flowing through the conduit 11 is measured by the flowmeter 14 which is placed in the downstream side of the pump mechanism 13, and a measured flowrate is sent to the feedback controller 151 of the controller 15 (Step S131). Subsequently, the feedback controller 151 determines whether or not the measured flowrate obtained by the flowmeter 14 is equal to a predetermined flowrate which is inputted from the outside (Step S132).
In a case where the measured flowrate differs from the predetermined flowrate, the feedback controller 151 sends a command value of pressure as an electrical signal to the electro-pneumatic regulator 133 of the pump mechanism 13 on the basis of the measured flowrate and controls pressure applied to the flexible chamber 131 so that the flowrate of the liquid flowing through the conduit 11 is adjusted to the predetermined flowrate (Step S133). In a case where the measured flowrate is equal to the predetermined flowrate, the pressure applied to the flexible chamber 131 is kept. In the preferred embodiment, the feedback controller 151 utilizes a PID Control as a control method of the flowrate. An electrical signal sending from the feedback controller 151 to the electro-pneumatic regulator 133 is a current ranging from 4 to 20 mA.
In the pump mechanism 13, since a reaction force by the bellows 1311 of the flexible chamber 131 increases gradually with compression of the flexible chamber 131, normally, control of the electro-pneumatic regulator 133 is performed so that the pressure in the space between the flexible chamber 131 and the pressure chamber 132 increases gradually to make the measured flowrate equal to the predetermined flowrate.
In the liquid supply apparatus 1, it is checked repeatedly whether pumping out of the liquid from the pump mechanism 13 is complete or not (Step S134), and while pumping out of the liquid from the flexible chamber 131 is performed, steps for measuring a flowrate to control the pressure applied to the flexible chamber 131 (Steps S131 to 133) are repeated. With this operation, in the liquid supply apparatus 1, liquid supply to the external apparatus or the like is performed while controlling the flowrate so that the flowrate of the liquid flowing through the conduit 11 is adjusted to the predetermined flowrate. After the displacement sensor 135 detects the flexible chamber 131 changed to the compressed state, the pneumatic valve 1331 is closed, and pumping out of the liquid from the flexible chamber 131 to the conduit 11 is finished (Step S134). Flowrate measurement by the flowmeter 14 and control of the electro-pneumatic regulator 133 by the controller 15 are also ended, and then liquid supply to the external apparatus or the like is complete. In the preferred embodiment, an amount of liquid supply in one compression of the flexible chamber 131 is 30 ml.
In a case where liquid supply of the liquid supply apparatus 1 is repeated, backing to Step S11 after Step S13, the flexible chamber 131 is reexpanded and the liquid is sucked from the liquid supply source 12 (not shown in FIG. 7). In this case, when the flexible chamber 131 is expanded, since in the flexible chamber 131 and the conduit 11 air does not remain and the liquid is filled, steps for discharging air from the flexible chamber 131 and the conduit 11 (Steps S12, S121) are omitted, and then Steps S11 and S13 are repeated.
As discussed above, in the liquid supply apparatus 1, while pressure is applied to the flexible chamber 131 of the pump mechanism 13 and the liquid in the flexible chamber 131 is pumped out to the conduit 11, the flowrate of the liquid flowing through the conduit 11 is measured by the flowmeter 14, and the pressure applied to the flexible chamber 131 is controlled by the feedback controller 151 so that the measured flowrate is adjusted to the predetermined flowrate. In the liquid supply apparatus 1, by controlling the pressure applied to the flexible chamber 131 with high accuracy, it is possible to supply the liquid of a small flowrate while controlling the flowrate accurately.
In the liquid supply apparatus 1, since the flexible chamber 131 of the pump mechanism 13 and the tube 143 of the flowmeter 14 are made of resin with high durability against various kinds of liquid and the other various constituent elements which are exposed to the liquid are made of materials such as fluorocarbon resin or the like with high durability, it is possible to perform supply of various kinds of liquid.
In the pump mechanism 13, since the flexible chamber 131 comprises the bellows 1311, it is possible to change a volume of the flexible chamber 131 easily, that is to say, by a small pressure. Since, in compressing the flexible chamber 131, the whole of the bellows 1311 is compressed, it is prevented that the bending of the flexible chamber 131 in compressing occurs in a part of the flexible chamber 131, and it is possible to suppress deterioration caused by repeats of compression and expansion of the flexible chamber 131 in using the pump mechanism 13.
In the pump mechanism 13, since the electro-pneumatic regulator 133 adjusts the pressure in the pressure chamber 132 housing the flexible chamber 131, it is possible to control the pressure in the space between the pressure chamber 132 and the flexible chamber 131 with high response and high accuracy.
In the pump mechanism 13, the lower end 1313 of the flexible chamber 131 is made free as shown in FIG. 2. FIG. 9 is a view illustrating a part of a pump mechanism 93 where a lower end of a flexible chamber is not made free as a comparative example. In the pump mechanism 93 of the comparative example, a cylinder part 9322 is provided at a lower part of a pressure chamber 932, and inside the cylinder part 9322 a piston 9323 passing through the bottom of the flexible chamber 932 to be connected to a lower end 9313 of a flexible chamber 931 is provided. The piston 9323 comprises a disk-shaped bottom part 9324 positioned inside of the cylinder part 9322 and a cylindrical shaft 9325 projecting upward from the bottom part 9324 to be inserted into a through-hole 9326 in the bottom of the pressure chamber 932. Sealing is provided between the bottom part 9324 and an internal surface of the cylinder part 9322, and between an external surface of the shaft 9325 and an internal surface of the through-hole 9326 so that air does not leak.
In the pump mechanism 93, by supplying air between the pressure chamber 932 and the flexible chamber 931 to compress the flexible chamber 931, the liquid in the flexible chamber 931 is pumped out. Also, air is supplied to a space surrounded by the bottom of the pressure chamber 932, the cylinder part 9322, and the bottom part 9324 of the piston 9323, the bottom part 9324 of the piston 9323 gets away from the bottom of the pressure chamber 932 relatively. The flexible chamber 931 is expanded and the liquid is supplied to the flexible chamber 931.
In the pump mechanism 93, in any case of pumping out the liquid from the flexible chamber 931 and supplying the liquid to the flexible chamber 931, the piston 9323 moves up and down together with the lower end 9313 of the flexible chamber 931. In movement of the piston 9323, since the bottom part 9324 rubs with the internal surface of the cylinder part 9322 and the shaft 9325 rubs with the internal surface of the through-hole 9326, frictional resistance occurs. When the piston 9323 moves at low speed, chattering or jerking occurs in up and down movements of the lower end 9313 of the flexible chamber 931, and compression and expansion of the flexible chamber 931 becomes unstable.
On the other hand, in the pump mechanism 13 in accordance with the above preferred embodiment, since the lower end 1313 of the flexible chamber 131 is made free as shown in FIG. 2, it is possible to compress the flexible chamber 131 stably (i.e., while preventing occurrence of the chattering or jerking) by preventing rubbing against the pressure chamber 132 of the flexible chamber 131 or by making the frictional resistance very small even if rubbing occurs. As a result, it is possible to control the flowrate of the liquid to be supplied with higher accuracy in the liquid supply apparatus 1.
In the pump mechanism 13, by providing the displacement sensor 135 for detecting a displacement of the lower end 1313 of the flexible chamber 131, it is possible to monitor movement of the flexible chamber 131 in the pressure chamber 132, and it is therefore possible to increase reliability of the liquid supply apparatus 1. By positioning the leakage sensor 136 at the bottom of the pressure chamber 132, even if the liquid leaks from the flexible chamber 131, the leakage of the liquid is detected immediately, and it is further possible to increase reliability of the liquid supply apparatus 1.
In the flowmeter 14, the flow of the liquid is kept laminar, and then the pressure difference between both ends of the tube 143 and the flowrate have the approximately proportionality relation. This prevents resolution of the pressure difference and the flowrate from changing considerably and makes the measuring accuracy of the flowrate almost constant regardless of the pressure difference. Since a change of the flowrate relative to that of the pressure difference increases, in comparison with another measurement within turbulent region where the flowrate is approximately proportioned to square root of the pressure difference, the measuring accuracy can be improved and further the range of the flowrate which can be measured is expanded. In the flowmeter 14, the Reynolds number of the flow within the tube 143 is kept to be less than or equal to 2000 and a transitional flow where a state of the flow becomes unstable is avoided. After the flow is made laminar completely, the pressure difference is obtained and it is thereby possible to measure the flowrate with high accuracy stably, even if the flowrate of the liquid is very small. Consequently, it is possible to supply the liquid of a small flowrate while controlling the flowrate with higher accuracy in the liquid supply apparatus 1.
By using a long tube 143 as a pressure loss part to reduce the pressure of the liquid gradually in the flowmeter 14, even if the flowrate of the liquid which has a small flowrate is measured, a significant pressure difference can be obtained without making the inner diameter of the tube 143 extremely small. Therefore, it becomes possible to make the inner diameter of the tube 143 relatively large and there is no need to make the flow velocity of the liquid flowing through the tube 143 extremely high. This results in preventing foreign substances from blocking the tube 143 and also occurring cavitation in the vicinity of an end of the tube 143 in the downstream side and the like. The flowmeter 14 is especially suitable for the liquid supply apparatus 1 which needs high accurate flowrate measurement of the liquid of the small flowrate.
FIG. 10 is a view illustrating a construction of a liquid supply apparatus 1 a in accordance with the second preferred embodiment of the present invention. As shown in FIG. 10, the liquid supply apparatus 1 a has the same constituents as the liquid supply apparatus 1 shown in FIG. 1 and further comprises the other pump mechanism 13 a having the same structure as the pump mechanism 13. In the following description, the pump mechanism 13 and the pump mechanism 13 a are respectively described as “first pump mechanism 13” and “second pump mechanism 13 a” for distinctiveness. Other constituent elements are the same as those of FIG. 1 and the constituent elements are represented by the same reference signs in the following description. In FIG. 10, hatching of cross sections are omitted.
In the liquid supply apparatus 1 a, the conduit 11 is divided into two conduits between the liquid supply source 12, and the first pump mechanism 13 and the second pump mechanism 13 a. Divided conduits 11 connect between the first pump mechanism 13 and the second pump mechanism 13 a, and the flowmeter 14. In two divided parts of the conduit 11, the first pump mechanism 13 is connected between the first check valve 112 and the second check valve 113 which are installed on one divided conduit, and the second pump mechanism 13 a is connected between the third check valve 112 a and the fourth check valve 113 a which are installed on the other divided conduit. The flowmeter 14 for measuring a flowrate of the liquid flowing through the conduit 11 is located in a downstream side of a connected point of the above divided conduits.
The second pump mechanism 13 a comprises, like the first pump mechanism 13, the flexible chamber 131 a which is made of resin (hereinafter, the flexible chamber 131 a is referred to as “second flexible chamber 131 a”. The flexible chamber 131 of the first pump mechanism 13 is referred to as “first flexible chamber 131” for distinctiveness), a pressure chamber 132 a housing the second flexible chamber 131 a, and an electro-pneumatic regulator 133 a for adjusting a pressure in a space between the pressure chamber 132 a and the second flexible chamber 131 a.
The second flexible chamber 131 a comprises, like the first flexible chamber 131, a bellows 1311 a, and a lower end of the bellows 1311 a is made free. In the pressure chamber 132 a, like the pressure chamber 132 shown in FIG. 2, provided are a displacement sensor for detecting a displacement of the lower end of the bellows 1311 a with respect to the pressure chamber 132 a, and a leakage sensor for detecting a leakage, if there is a leakage of the liquid from the second flexible chamber 131 a. Also in the second pump mechanism 13 a, the displacement sensor detects whether the second flexible chamber 131 a is in a compressed state, an expanded state, or an intermediate state between the compressed state and the expanded state.
The pressure chamber 132 a is connected to the electro-pneumatic regulator 133 a through a pneumatic valve 1331 a and is also connected to the ejector 134 of the first pump mechanism 13 through a pneumatic valve 1341 a. In other words, the first pump mechanism 13 and the second pump mechanism 13 a share the ejector 134. The pneumatic valves 1331 a, 1341 a are driven by electromagnetic valves 1332 a, 1342 a. In the second pump mechanism 13 a, these valves, the electro-pneumatic regulator 133 a, and the ejector 134 are controlled by the controller 15, and the second flexible chamber 131 a is compressed and expanded. By this, the liquid is sucked from the liquid supply source 12 to be stored in the second flexible chamber 131 a, and it is pumped out to the conduit 11.
In the liquid supply apparatus 1 a, by control of the controller 15, compression of one chamber of the first flexible chamber 131 of the first pump mechanism 13 and the second flexible chamber 131 a of the second pump mechanism 13 a and concurrent expansion of the other chamber of the first flexible chamber 131 and the second flexible chamber 131 a are performed alternately to the first flexible chamber 131 and the second flexible chamber 131 a. By this, continuous supply of the liquid is performed.
FIG. 11 and FIG. 12 are views illustrating an operation flow of the liquid supply apparatus 1 a for supplying the liquid. FIG. 13 is a view illustrating a state of switching between the first pump mechanism 13 and the second pump mechanism 13 a in each step after the later discussed Step S23. A reference sign of the step is assigned to a position corresponding to each step. Next, referring to FIG. 11 to FIG. 13, an operation flow of the liquid supply apparatus 1 a will be discussed.
When the liquid is supplied by the liquid supply apparatus 1 a, like in the first preferred embodiment, a user fills the first pump mechanism 13, the second pump mechanism 13 a, and the conduit 11 with liquid for preparation. The ejector 134 discharges air between the first flexible chamber 131 and the pressure chamber 132, and pressure in the pressure chamber 132 is reduced. The first flexible chamber 131 changes from the compressed state (see FIG. 3) to the expanded state (see FIG. 2), and the liquid is sucked from the liquid supply source 12 to be stored in the first flexible chamber 131. Concurrently with this operation, the ejector 134 discharges air between the second flexible chamber 131 a and the pressure chamber 132 a, and pressure in the pressure chamber 132 a is reduced. The second flexible chamber 131 a changes from the compressed state to the expanded state, and the liquid is sucked from the liquid supply source 12 to be supplied to the second flexible chamber 131 a and stored therein (Step S21).
After the first flexible chamber 131 and the second flexible chamber 131 a becomes the expanded state, it is determined whether or not air remains in the first flexible chamber 131, the second flexible chamber 131 a, and the conduit 11 (Step S22). In a case where air remains, the electro-pneumatic regulators 133, 133 a supply air between the first flexible chamber 131 and the pressure chamber 132, and between the second flexible chamber 131 a and the pressure chamber 132 a to increase pressures in the pressure chambers 132, 132 a. With this operation, the first flexible chamber 131 and the second flexible chamber 131 a change from the expanded state to the compressed state, and air in the first flexible chamber 131, the second flexible chamber 131 a, and the conduit 11 is discharged from a downstream side of the conduit 11 to the outside of the liquid supply apparatus 1 a (Step S221).
After the first flexible chamber 131 and the second flexible chamber 131 a are made to the compressed state, liquid supply to the first flexible-chamber 131 and the second flexible chamber 131 a is restarted back to Step S21. In the liquid supply apparatus 1 a, liquid supply to the first flexible chamber 131 and the second flexible chamber 131 a and discharge of air from the first flexible chamber 131, the second flexible chamber 131 a, and the conduit 11 are repeated (repeats Steps S21 to S221) until air in the first flexible chamber 131, the second flexible chamber 131 a, and the conduit 11 is completely discharged and the liquid filling is finished.
After air is completely discharged from the first flexible chamber 131, the second flexible chamber 131 a, and the conduit 11 (Step S22), the electro-pneumatic regulator 133 of the first pump mechanism 13 supplies air to the pressure chamber 132 to apply pressure to the first flexible chamber 131, and the first flexible chamber 131 in the expanded state is compressed. Pumping out of the liquid stored in the first flexible chamber 131 to the conduit 11 is started, and the liquid is supplied to the external apparatus or the like (Step S23).
In the second pump mechanism 13 a, a little before compression of the first flexible chamber 131 is stopped and pumping out of the liquid from the first pump mechanism 13 is stopped, air supply to the pressure chamber 132 a by the electro-pneumatic regulator 133 a is started, and then compression of the second flexible chamber 131 a in the expanded state is started. The liquid stored in the second flexible chamber 131 a is pumped out to the conduit 11 concurrently with pumping out of the liquid from the first flexible chamber 131 (Step S24).
Subsequently, compression of the first flexible chamber 131 is stopped in the first pump mechanism 13 (Step S25). In the liquid supply apparatus 1 a, also after compression of the first flexible chamber 131 is stopped, compression of the second flexible chamber 131 a continues in the second pump mechanism 13 a, and the liquid is continuously pumped out to the conduit 11. In the first pump mechanism 13, once compression of the first flexible chamber 131 is stopped, discharge of air from the pressure chamber 132 is started by the ejector 134 to expand the first flexible chamber 131 in the compressed state. The liquid is sucked from the liquid supply source 12 to the first flexible chamber 131 to be stored therein (Step S26).
In the first pump mechanism 13, before compression of the second flexible chamber 131 a (i.e., pumping out of the liquid from the second pump mechanism 13 a) is stopped, discharge of air from the pressure chamber 132 by the ejector 134 (i.e., expansion of the first flexible chamber 131) is stopped (Step S27). After that, a little before compression of the second flexible chamber 131 a is stopped, air supply to the pressure chamber 132 by the electro-pneumatic regulator 133 is started to compress the first flexible chamber 131 in the expanded state. Then the liquid stored in the first flexible chamber 131 is pumped out to the conduit 11 concurrently with pumping out of the liquid from the second flexible chamber 131 a (Step S31).
Subsequently, compression of the second flexible chamber 131 a is stopped in the second pump mechanism 13 a (Step S32). In the liquid supply apparatus 1 a, also after compression of the second flexible chamber 131 a is stopped, compression of the first flexible chamber 131 continues in the first pump mechanism 13, and the liquid is continuously pumped out to the conduit 11. In the second pump mechanism 13 a, once compression of the second flexible chamber 131 a is stopped, discharge of air from the pressure chamber 132 a is started by the ejector 134, and the second flexible chamber 131 a in the compressed state is expanded to increase a volume thereof. The liquid is sucked from the liquid supply source 12 to the second flexible chamber 131 a to be stored therein (Step S33).
In the second pump mechanism 13 a, before compression of the first flexible chamber 131 (i.e., pumping out of the liquid from the first pump mechanism 13) is stopped, discharge of air from the pressure chamber 132 a by the ejector 134 (i.e., expansion of the second flexible chamber 131 a) is stopped (Step S34). Back to Step S24, a little before compression of the first flexible chamber 131 is stopped, air supply to the pressure chamber 132 a by the electro-pneumatic regulator 133 a is started to apply pressure to the second flexible chamber 131 a in the expanded state, and the second flexible chamber 131 a is compressed. By reducing a volume of the second flexible chamber 131 a, the liquid stored in the second flexible chamber 131 a is pumped out to the conduit 11 concurrently with pumping out of the liquid from the first flexible chamber 131 (Step S24).
Subsequently, compression of the first flexible chamber 131 is complete (Step S25), and the first flexible chamber 131 is expanded to suck the liquid before stopping compression of the second flexible chamber 131 a (Steps S26, S27). After compression of the first flexible chamber 131 and pumping out of the liquid are started, compression of the second flexible chamber 131 a is stopped (Steps S31, S32). After that, before stopping compression of the first flexible chamber 131, the second flexible chamber 131 a is expanded to suck the liquid (Steps S33, S34), and back to Step S24 again.
As discussed above, in the liquid supply apparatus 1 a, Steps S24 to S34 are repeated until it is determined liquid supply is complete. In other words, almost concurrent pumping out of the liquid from the second flexible chamber 131 a to the conduit 11 and storing of the liquid in the first flexible chamber 131, and almost concurrent pumping out of the liquid from the first flexible chamber 131 to the conduit 11 and storing of the liquid in the second flexible chamber 131 a, are alternately repeated. As a result, pumping out of the liquid from the first pump mechanism 13 and/or the second pump mechanism 13 a are continuously performed in the liquid supply apparatus 1 a. In the liquid supply apparatus 1 a, the second flexible chamber 131 a may be compressed before compression of the first flexible chamber 131. The initial liquid filling may be performed by alternately repeating compression of one chamber of the first flexible chamber 131 and the second flexible chamber 131 a and concurrent expansion of the other chamber.
In the liquid supply apparatus 1 a, while the first pump mechanism 13 and the second pump mechanism 13 a are pumping out the liquid, that is to say, during Step S23 and repeated Step S24 to S34 shown in FIG. 11 and FIG. 12, a flowrate control shown in FIG. 14 is continuously performed. Next discussion will be made on an operation flow of the liquid supply apparatus 1 a for controlling a flowrate.
In the liquid supply apparatus 1 a, when the first pump mechanism 13 starts pumping out of the liquid to the conduit 11 in Step S23 (see FIG. 11, FIG. 13), like in the first preferred embodiment, a flowrate of the liquid flowing through the conduit 11 is measured by the flowmeter 14, and a measured flowrate is sent to the feedback controller 151 of the controller 15 (Step S41). Subsequently, it is determined whether or not the measured flowrate obtained by the flowmeter 14 is equal to a predetermined flowrate (Step S42).
In a case where the measured flowrate differs from the predetermined flowrate, the feedback controller 151 controls the electro-pneumatic regulator 133 of the first pump mechanism 13, and the pressure applied to the first flexible chamber 131 is controlled so that the measured flowrate is adjusted to the predetermined flowrate (Step S43). Also in the second preferred embodiment, the feedback controller 151 utilizes a PID Control as a control method of the flowrate.
In the liquid supply apparatus 1 a, it is checked repeatedly whether or not pumping out of the liquid from the first pump mechanism 13 and the second pump mechanism 13 a is complete (Step S44), in a case where it is not complete, back to Step S41, the steps for measuring a flowrate to control pressure(s) applied to the first flexible chamber 131 and/or the second flexible chamber 131 a (Steps S41 to S43) are repeated.
In the liquid supply apparatus 1 a, during Steps S23 to S24 and Steps S32 to S24 shown in FIG. 13, the first pump mechanism 13 is controlled and the measured flowrate is made equal to the predetermined flowrate. During Steps S25 to S31, a flowrate is measured by the flowmeter 14 placed in a downstream side of the second pump mechanism 13 a, on the basis of a measured flowrate, the electro-pneumatic regulator 133 a of the second pump mechanism 13 a is controlled. By this, the pressure applied to the second flexible chamber 131 a is controlled so that the measured flowrate is adjusted to the predetermined flowrate.
During Steps S24 to S25 and Steps S31 to S32, the electro-pneumatic regulators 133, 133 a of the first pump mechanism 13 and the second pump mechanism 13 a are controlled on the basis of the measured flowrate of the flowmeter 14, so that pressures applied to the first flexible chamber 131 and the second flexible chamber 131 a are parallel controlled. In other words, in the liquid supply apparatus 1 a, a period after starting pumping out of the liquid from the first flexible chamber 131 and a period before ending pumping out of the liquid from the first flexible chamber 131 respectively overlap a period before ending pumping out of the liquid from the second flexible chamber 131 a and a period after starting pumping out of the liquid from the second flexible chamber 131 a. In these overlapping periods, equivalent pressures are applied to the first flexible chamber 131 and the second flexible chamber 131 a to be controlled so that the measured flowrate of the flowmeter 14 is made equal to the predetermined flowrate.
FIG. 15 is a view illustrating a change of a flowrate of the liquid flowing through the conduit 11 in the liquid supply apparatus 1 a. In the liquid supply apparatus 1 a, in a case where compression of one chamber of the first flexible chamber 131 and the second flexible chamber 131 a is started when compression of the other chamber continues (i.e., Steps S24, S31), pressure applied to the one chamber (i.e., a command value of pressure sent to the electro-pneumatic regulator) is made the same as pressure applied to the other chamber as discussed above. At this time, since the flexible chamber started compression is more expanded state than the flexible chamber under compression, a reaction force by the bellows of the flexible chamber started compression is small. As a result, a flowrate of the liquid pumped out to the conduit 11 becomes slightly greater than the predetermined flowrate during Steps S24 to S25 and Steps S31 to S32 as shown in FIG. 15.
In the liquid supply apparatus 1 a, however, since a flowrate control is performed on the basis of the measured flowrate of the flowmeter 14 as discussed above, such slight variations in flowrate are immediately suppressed. As a result, it is prevented great flowrate variations causing problems occur in liquid supply, and it is possible to maintain a constant flowrate always in the liquid supply apparatus 1 a.
As discussed above, in the liquid supply apparatus 1 a, compression of one chamber of the first flexible chamber 131 of the first pump mechanism 13 and the second flexible chamber 131 a of the second pump mechanism 13 a and concurrent expansion of the other chamber are alternately performed, the flowrate of the liquid flowing through the conduit 11 is measured by the flowmeter 14, and further on the basis of the measured flowrate, the pressures applied to the first flexible chamber 131 and the second flexible chamber 131 a are controlled by the feedback controller 151. In the liquid supply apparatus 1 a, it is possible to supply the liquid of a small flowrate long hours continuously while controlling pressures applied to the first flexible chamber 131 and the second flexible chamber 131 a with high accuracy to control the flowrate accurately.
In the liquid supply apparatus 1 a, before compression of one chamber of the first flexible chamber 131 and the second flexible chamber 131 a is stopped, expansion of the other chamber is complete to start compression. With this operation, by overlapping a starting period with an ending period of pumping movement of the liquid by the first pump mechanism 13 and the second pump mechanism 13 a, it is possible to suppress flowrate variations easily which occur in switching of compressions of the first flexible chamber 131 and the second flexible chamber 131 a. As a result, it becomes possible to perform continuous supply of the liquid of the small flowrate stably.
In the liquid supply apparatus 1 a, since the second pump mechanism 13 a has the same constituents as the first pump mechanism 13 and the second pump mechanism 13 a is made of resin with high durability against various kinds of liquid, it is possible to supply various kinds of liquid. Like the first flexible chamber 131, it is possible to change a volume of the second flexible chamber 131 a comprising the bellows 1311 a easily, and it is also possible to suppress deterioration caused by repeats of compression and expansion of the second flexible chamber 131 a.
In the second pump mechanism 13 a, since the electro-pneumatic regulator 133 a is used in compression of the second flexible chamber 13 la, it is possible to control the pressure in the space between the pressure chamber 132 a and the second flexible chamber 131 a with high response and high accuracy. By making the lower end of the second flexible chamber 131 a free, it is possible to compress the second flexible chamber 131 a stably and it is also possible to control a flowrate of the liquid to be supplied with higher accuracy. By positioning the displacement sensor and the leakage sensor in the pressure chamber 132 a, it is possible to increase reliability of the liquid supply apparatus 1.
In the liquid supply apparatus 1 a, like in the first preferred embodiment, it is possible to measure a flowrate with high accuracy stably by the flowmeter 14, even if the flowrate of the liquid is very small.
Next, discussion will be made on a liquid supply apparatus in accordance with the third preferred embodiment of the present invention. The liquid supply apparatus in accordance with the third preferred embodiment is provided a pump mechanism 13 b shown in FIG. 16 instead of the pump mechanism 13 of the liquid supply apparatus 1 shown in FIG. 1. Other constituent elements are the same as those of FIG. 1 and the constituent elements are represented by the same reference signs in the following description.
In the pump mechanism 13b of the liquid supply apparatus in accordance with the third preferred embodiment, compression and expansion of a flexible chamber 131 b is performed by a motor which is a different power source from that of the pump mechanism 13 of the liquid supply apparatus 1 shown in FIG. 1. As shown in FIG. 16, in the pump mechanism 13 b, a moving mechanism 137 for compressing or expanding the flexible chamber 131 b by moving a lower end of the flexible chamber 131 b in a vertical direction and a motor 138 for driving the moving mechanism 137 are provided, instead of the pressure chamber 132 of the pump mechanism 13, the electro-pneumatic regulator 133, the ejector 134, and various pneumatic valves and electromagnetic valves shown in FIG. 1.
The moving mechanism 137 comprises a moving plate 1371 connected to the lower end of the flexible chamber 131 b, a ball screw 1372 extending in the vertical direction, a nut 1373 which is fixed on the moving plate 1371 and into which the ball screw 1372 is inserted, a guide 1374 for leading the moving plate 1371 in the vertical direction, and a timing belt 1375 for connecting the ball screw 1372 to the motor 138. An output torque of the motor 138 is controllable and to the motor 138 a torque control amplifier 1381 is connected.
In the moving mechanism 137, the motor 138 rotates the ball screw 1372, so that the moving plate 1371 moves along the guide 1374 in the vertical direction smoothly. When the moving plate 1371 moves upward to be driven by the motor 138, the lower end of the flexible chamber 131 b also moves upward (i.e., toward an upper end of the flexible chamber 131 b) to apply pressure to the flexible chamber 131 b, and then the liquid in the flexible chamber 131 b is pumped out to the conduit 11. In other words, the moving mechanism 137 functions as a pressure mechanism for applying pressure to the flexible chamber 131 b by a torque outputted from the motor 138.
When the moving plate 1371 moves downward to be driven by the motor 138, the lower end of the flexible chamber 131 b moves away from the upper end to reduce pressure in the flexible chamber 131 b. By this, the liquid is sucked from the liquid supply source 12 (see FIG. 1) to be supplied to the flexible chamber 131 b and stored therein.
In the liquid supply apparatus in accordance with the third preferred embodiment, by compressing the flexible chamber 131 b in the pump mechanism 13 b, the liquid in the flexible chamber 131 b is pumped out to the conduit 11. While the liquid is flowing through the conduit 11, a flowrate of the liquid flowing through the conduit 11 is measured by the flowmeter 14 (see FIG. 1) placed in a downstream side of the pump mechanism 13 b. On the basis of a measured flowrate, the output torque of the motor 138 is controlled by the feedback controller 151 (see FIG. 1) of the controller 15 through the torque control amplifier 1381, and the pressure applied to the flexible chamber 131 b is controlled so that the measured flowrate is adjusted to a predetermined flowrate.
As discussed above, in the liquid supply apparatus in accordance with the third preferred embodiment, since the pump mechanism 13 b can be driven without a compressor or a vacuum source, it is possible to simplify the construction of the liquid supply apparatus.
Next, referring to FIG. 17, a substrate processing apparatus 2 comprising the liquid supply apparatus 1 shown in FIG. 1 in accordance with the fourth preferred embodiment of the present invention will be discussed. The substrate processing apparatus 2 is a so-called single wafer-type processing apparatus for etching one semiconductor substrate 9 (hereinafter, referred to as simply “substrate 9”).
As shown in FIG. 17, the substrate processing apparatus 2 includes a first conduit 21 through which pure water flows and a second conduit 22 through which hydrofluoric acid flows. The first conduit 21 and the second conduit 22 are connected at a downstream of both conduits. At a connected point of the first conduit 21 and the second conduit 22 a mixing valve 241 is installed, the pure water from the first conduit 21 and the hydrofluoric acid from the second conduit 22 are mixed in the mixing valve 241 and a processing liquid is generated.
The first conduit 21 is connected to an external pure water supply apparatus through a valve 211 and a regulator 212 in an upstream side of the first conduit 21. In an upstream side of the second conduit 22, the liquid supply apparatus 1 for supplying the hydrofluoric acid in accordance with the first preferred embodiment is placed. In the flowing description, the constituent elements of the liquid supply apparatus 1 will be discussed referring to the reference signs in FIG. 1.
In the substrate processing apparatus 2, a third conduit 24 through which the processing liquid which is a mixture of the pure water and the hydrofluoric acid flows is provided in a downstream side of the mixing valve 241, and in a downstream side of the third conduit 24 (i.e., a downstream side of the connected point of the first conduit 21 and the second conduit 22) a substrate holding part 26 for holding the substrate 9 is positioned. A nozzle 27 is located in an upper part of the substrate holding part 26, and the nozzle 27 serves as a processing liquid supply part which is connected to the downstream side of the third conduit 24 and supplies the processing liquid to the substrate 9.
The substrate holding part 26 has a chuck 261 for holding the approximately disk-shaped substrate 9 on the lower surface and the periphery of the substrate 9, a rotating mechanism 262 for rotating the substrate 9, and a process cup 263 for covering the circumference of the chuck 261. The rotating mechanism 262 has a shaft 2621 coupled to the bottom of the chuck 261 and a motor 2622 for rotating the shaft 2621. By driving the motor 2622, the substrate 9 rotates together with the shaft 2621 and the chuck 261. The process cup 263 has a side wall 2631, placed in the circumference of the chuck 261, for preventing the processing liquid supplied to the substrate 9 from splashing around, and an outlet 2632, provided in the bottom of the process cup 263, for discharging the processing liquid supplied to the substrate 9.
In the substrate processing apparatus 2, by opening the valve 211, the pure water is supplied from the pure water supply apparatus to the first conduit 21. At the same time, by driving the pump mechanism 13 (see FIG. 1) of the liquid supply apparatus 1 to apply pressure to the flexible chamber 131 where the hydrofluoric acid is stored in advance, the hydrofluoric acid is pumped out from the flexible chamber 131 to the conduit 11 and is supplied to the second conduit 22. In the mixing valve 241, the hydrofluoric acid supplied to the second conduit 22 is mixed with the pure water supplied to the first conduit 21 and the processing liquid of a dilute hydrofluoric acid is generated.
The processing liquid generated in the mixing valve 241 is supplied to the nozzle 27 through the third conduit 24 and is ejected from the nozzle 27 toward the center of the substrate 9 only a required amount. The substrate 9 is hold by the substrate holding part 26 and is rotated. The processing liquid supplied from the nozzle 27 spreads in all areas of the top of the substrate 9 while moving a top of the substrate 9 toward the outside thereof by the centripetal force, and then etching of the substrate 9 is performed. When the processing liquid moves out of the edge of the substrate 9, it is away from the substrate 9 and is received by the side wall 2631 of the process cup 263 or falls on the bottom of the process cup 263 directly and then the processing liquid is discharged from the outlet 2632.
In the liquid supply apparatus 1 of the substrate processing apparatus 2, the flowrate of the hydrofluoric acid flowing at a small flowrate is measured by the flowmeter 14 (see FIG. 1) with high accuracy stably, the pressure applied to the flexible chamber 131 of the pump mechanism 13 is controlled by the controller 15 (see FIG. 1) on the basis of a measured flowrate and a flowrate predetermined in advance, and thus it becomes possible to supply the hydrofluoric acid to the second conduit 22 while performing the flowrate control of the hydrofluoric acid of the small flowrate accurately. With this operation, in the substrate processing apparatus 2, a small supply rate of the hydrofluoric acid to the mixing valve 241 is controlled with high accuracy, and the processing liquid where the hydrofluoric acid is mixed at the desired concentration accurately is generated. Consequently, in the substrate processing apparatus 2, it is possible to perform etching of the substrate 9 with the processing liquid where the hydrofluoric acid is mixed at the desired concentration accurately. By performing etching with the dilute hydrofluoric acid of a concentration controlled with high accuracy, the etching rate is controlled high accurately and a more preferable processing result can be obtained. Also, by lowering the etching rate to suppress processing time variation in the center and the edge of the substrate 9, it is possible to improve uniformity of etching quality in a whole upper surface of the substrate 9.
Next, referring to FIG. 18, a substrate processing apparatus 2 a comprising the liquid supply apparatus 1 a shown in FIG. 10 in accordance with the fifth preferred embodiment of the present invention will be discussed. The substrate processing apparatus 2 a is a so-called batch-type processing apparatus for etching a plurality of substrates 9 simultaneously. As shown in FIG. 18, in the substrate processing apparatus 2 a, the liquid supply apparatus 1 a shown in FIG. 10 is placed instead of the liquid supply apparatus 1 of the substrate processing apparatus 2 shown in FIG. 17, and instead of the substrate holding part 26 and the nozzle 27, a process bath 25 is located in the downstream side of the third conduit 24 (i.e., the downstream side of the connected point of the first conduit 21 and the second conduit 22). The process bath 25 stores the processing liquid and where the approximately disk-shaped substrates 9 are dipped vertically. Other constituent elements are the same as those of FIG. 17 and the constituent elements are represented by the same reference signs in the following description. The constituent elements of the liquid supply apparatus 1 a will be discussed referring to the reference signs in FIG. 10.
As shown in FIG. 18, the substrate processing apparatus 2 a, like in the fourth preferred embodiment, includes the first conduit 21 through which the pure water flows, the second conduit 22 through which the hydrofluoric acid flows and connected to the first conduit 21 in the mixing valve 241, the liquid supply apparatus 1 a in accordance with the second preferred embodiment, placed in the upstream side of the second conduit 22 to supply the hydrofluoric acid to the second conduit 22, and the third conduit 24 installed in the downstream side of the mixing valve 241 and through which the processing liquid, which is the mixture of the pure water and the hydrofluoric acid, flows.
In the substrate processing apparatus 2 a, like in the fourth preferred embodiment, the pure water supplied to the first conduit 21 and the hydrofluoric acid supplied to the second conduit 22 are mixed in the mixing valve 241 and the processing liquid of the dilute hydrofluoric acid solution is generated. At this time, in the liquid supply apparatus 1 a, the flowrate of the hydrofluoric acid flowing at the very small flowrate is stably measured by the flowmeter 14 (see FIG. 10) with high accuracy, pressures applied to the first flexible chamber 131 and the second flexible chamber 131 a (see FIG. 10) are controlled by the controller 15 (see FIG. 10) on the basis of the measured flowrate and the predetermined flowrate, and thus the hydrofluoric acid is supplied to the mixing valve 241 through the second conduit 22 while performing the flowrate control of the hydrofluoric acid of the small flowrate accurately. As a result, the processing liquid where the hydrofluoric acid is mixed accurately at the desired concentration is generated.
The processing liquid generated in the mixing valve 241 is supplied to the process bath 25 from the bottom thereof through the third conduit 24. In the process bath 25, the plurality of substrates 9 held in the process bath 25 are dipped gradually from the bottoms into the processing liquid which is supplied to the process bath 25 and is stored therein, and then etching of the substrates 9 is performed.
In the substrate processing apparatus 2 a, like in the fourth preferred embodiment, it is possible to perform etching of the substrate 9 with the processing liquid where the hydrofluoric acid is mixed accurately at the desired concentration. By performing etching with the dilute hydrofluoric acid of a concentration controlled with high accuracy, the etching rate is controlled high accurately and it is possible to obtain a more preferable processing result. Also, by lowering the etching rate to suppress processing time variation in an upper side and a lower side of the substrate 9, it is possible to improve uniformity of etching quality in a whole upper surface of the substrate 9.
Since in the substrate processing apparatus 2 a it is possible to supply the hydrofluoric acid of a small flowrate long hours continuously while controlling the flowrate accurately by the liquid supply apparatus 1 a, the substrate processing apparatus 2 a is especially suitable for batch-type etching (and the other substrate processing) which requires a large amount of processing liquid in one process. In the liquid supply apparatus 1 a, by overlapping a starting period with an ending period of pumping movement of the liquid by the first pump mechanism 13 and the second pump mechanism 13 a, it is possible to suppress flowrate variations easily which occur in switching of compressions of the first flexible chamber 131 and the second flexible chamber 131 a, and thus it becomes possible to keep the processing liquid for etching of the substrates 9 at the desired concentration easily.
Though the preferred embodiments of the present invention have been discussed above, the present invention is not limited to the above-discussed preferred embodiments, but allows various variations.
The flexible chambers provided in respective pump mechanisms of the liquid supply apparatuses in accordance with the above preferred embodiments may be made of various materials except resin. Each flexible chamber does not necessarily comprise the bellows and for example, the whole of the flexible chamber may be almost spherical. Also in this case, in the liquid supply apparatuses in accordance with the first and second preferred embodiments, an almost spherical flexible chamber applied pressure in the pressure chamber is compressed, and the liquid is pumped out to the conduit 11.
In the liquid supply apparatuses in accordance with the first and second preferred embodiments, in sucking the liquid from the liquid supply source 12 by expanding the flexible chamber, pressure reduction is not necessarily performed until pressure in the pressure chamber becomes negative. For example, the bellows expands by a reaction force of the bellows compressed by reducing pressure around the flexible chamber to a certain degree, and the liquid may be sucked from the liquid supply source 12. After sealing the liquid supply source 12, a pump mechanism is provided, by applying pressure to the liquid in the liquid supply source 12 to pump out the liquid to the pump mechanism, the liquid may be supplied to the flexible chamber.
In the liquid supply apparatus 1 a in accordance with the second preferred embodiment, two pump mechanisms 13 b of the liquid supply apparatus in accordance with the third preferred embodiment may be provided instead of the first pump mechanism 13 and the second pump mechanism 13 a.
The displacement sensor 135 and the leakage sensor 136 positioned in the pump mechanism 13 are not limited to the structures described in the above preferred embodiments and they may have various structures. For example, a float type leakage sensor 136 may be used. In a case where electricity is not available in a liquid detection because of low conductivity of a liquid in the flexible chamber or the like, the leakage sensor 136 may have a structure where the leakage sensor 136 receives a reflection light of a light emitted toward the bottom of the pressure chamber and detects a leakage according to a change of optical properties of the reflection light.
The tube 143 of the flowmeter 14 is not necessarily made of resin and it may be made of other materials. In this case, it is preferable that the tube 143 is made of materials with high durability against various kinds of liquid. The storage part 145 and the operation part 146 of the flowmeter 14 may be formed integrally with the feedback controller 151 of the controller 15.
In the substrate processing apparatus 2 in accordance with the fourth preferred embodiment, the liquid supply apparatus 1 a having the two flexible chambers or the liquid supply apparatus in accordance with the third preferred embodiment where the motor 138 is the power source may be placed instead of the liquid supply apparatus 1 having one flexible chamber 131. In the substrate processing apparatus 2 a in accordance with the fifth preferred embodiment, the liquid supply apparatus 1 or the liquid supply apparatus in accordance with the third preferred embodiment may be placed instead of the liquid supply apparatus 1 a.
In the substrate processing apparatuses in accordance with the fourth and fifth preferred embodiments, liquids except the pure water and the hydrofluoric acid may be mixed, and other processes (cleaning process, for example) except etching of the substrate 9 may be performed.
While the invention has been shown and described in detail, the foregoing description is in all aspects illustrative and not restrictive. It is therefore understood that numerous modifications and variations can be devised without departing from the scope of the invention.
This application claims priority benefit under 35 U.S.C. Section 119 of Japanese Patent Application No. 2004-375294 filed in the Japan Patent Office on Dec. 27, 2004, the entire disclosure of which is incorporated herein by reference.

Claims

1. A liquid supply apparatus for supplying a liquid, comprising:

a pump mechanism for pumping out a liquid to a conduit by applying pressure to a flexible chamber to reduce a volume of said flexible chamber;

a flowmeter placed in a downstream side of said pump mechanism for measuring a flowrate of said liquid flowing through said conduit; and

a controller for sending an electrical signal to said pump mechanism, said electrical signal controlling pressure applied to said flexible chamber so that said flowrate of said liquid flowing through said conduit is adjusted to a predetermined flowrate on the basis of a flowrate of said liquid obtained by said flowmeter.

2. The liquid supply apparatus according to claim 1, wherein

said flexible chamber is made of resin.

3. The liquid supply apparatus according to claim 1, wherein

said flexible chamber comprises a bellows.

4. The liquid supply apparatus according to claim 1, wherein

said pump mechanism comprises

a pressure chamber housing said flexible chamber; and

an electro-pneumatic regulator for adjusting pressure in a space between said pressure chamber and said flexible chamber.

5. The liquid supply apparatus according to claim 1, wherein

said flexible chamber comprises a bellows, and

said pump mechanism comprises

a pressure chamber housing said flexible chamber; and

an electro-pneumatic regulator for adjusting pressure in a space between said pressure chamber and said flexible chamber, wherein

one end of said flexible chamber is fixed to said pressure chamber and the other end is made free.

6. The liquid supply apparatus according to claim 5, wherein

said pump mechanism further comprises a displacement sensor for detecting a displacement of said other end with respect to said pressure chamber.

7. The liquid supply apparatus according to claim 4, wherein

said pump mechanism further comprises a leakage sensor located on an inner side of a bottom of said pressure chamber for detecting a leakage of said liquid from said flexible chamber.

8. The liquid supply apparatus according to claim 1, wherein

said pump mechanism comprises

a motor where an output torque is controlled; and

a press mechanism for applying pressure to said flexible chamber by a torque outputted from said motor.

9. The liquid supply apparatus according to claim 1, further comprising:

another pump mechanism which has the same structure as said pump mechanism, wherein

compression of one chamber of said flexible chamber of said pump mechanism and another flexible chamber of said another pump mechanism and concurrent expansion of the other chamber of said flexible chamber and said another flexible chamber are performed alternately to said flexible chamber and said another flexible chamber by control of said controller.

10. The liquid supply apparatus according to claim 9, wherein

before compression of said one chamber is stopped, expansion of said other chamber is stopped and compression of said other chamber is started.

11. The liquid supply apparatus according to claim 1, wherein

said flowmeter is a differential pressure flowmeter, and

said differential pressure flowmeter comprises

a round tube provided as a part of said conduit in which a flow of said liquid with a Reynolds number less than or equal to 2000 is formed;

a first pressure sensor placed between said pump mechanism and said round tube for measuring a pressure of said liquid flowing into said round tube; and

a second pressure sensor placed in a downstream side of said round tube for measuring a pressure of said liquid flowing out of said round tube.

12. The liquid supply apparatus according to claim 11, wherein

said round tube is made of resin.

13. A substrate processing apparatus for processing a substrate, comprising:

a first conduit through which a first liquid flows;

a second conduit through which a second liquid flows, said second conduit connected to said first conduit;

a liquid supply apparatus installed on an upstream side of said second conduit for supplying said second liquid; and

a process bath, located in a downstream side of a connected point of said first conduit and said second conduit, for storing a processing liquid which is a mixture of said first liquid and said second liquid, in which a substrate being dipped, wherein

said liquid supply apparatus comprises

a pump mechanism for pumping out said second liquid to a conduit connected to said second conduit by applying pressure to a flexible chamber to reduce a volume of said flexible chamber;

a flowmeter placed in a downstream side of said pump mechanism for measuring a flowrate of said second liquid flowing through said conduit; and

a controller for sending an electrical signal to said pump mechanism, said electrical signal controlling pressure applied to said flexible chamber so that said flowrate of said second liquid flowing through said conduit is adjusted to a predetermined flowrate on the basis of a flowrate of said second liquid obtained by said flowmeter.

14. The substrate processing apparatus according to claim 13, wherein

said flexible chamber is made of resin.

15. The substrate processing apparatus according to claim 13, wherein

said flexible chamber comprises a bellows.

16. The substrate processing apparatus according to claim 13, wherein

said pump mechanism comprises

a pressure chamber housing said flexible chamber; and

17. The substrate processing apparatus according to claim 13, wherein

said liquid supply apparatus further comprises another pump mechanism which has the same structure as said pump mechanism, and

18. The substrate processing apparatus according to claim 17, wherein

19. The substrate processing apparatus according to claim 13, wherein

said flowmeter is a differential pressure flowmeter, and

said differential pressure flowmeter comprises

a round tube provided as a part of said conduit in which a flow of said second liquid with a Reynolds number less than or equal to 2000 is formed;

a first pressure sensor placed between said pump mechanism and said round tube for measuring a pressure of said second liquid flowing into said round tube; and

a second pressure sensor placed in a downstream side of said round tube for measuring a pressure of said second liquid flowing out of said round tube.

20. A substrate processing apparatus for processing a substrate, comprising:

a substrate holding part for holding a substrate;

a first conduit through which a first liquid flows;

a processing liquid supply part, located in a downstream side of a connected point of said first conduit and said second conduit, for supplying a processing liquid which is a mixture of said first liquid and said second liquid to said substrate, wherein

said liquid supply apparatus comprises

21. The substrate processing apparatus according to claim 20, wherein

said flexible chamber is made of resin.

22. The substrate processing apparatus according to claim 20, wherein

said flexible chamber comprises a bellows.

23. The substrate processing apparatus according to claim 20, wherein

said pump mechanism comprises

a pressure chamber housing said flexible chamber; and

24. The substrate processing apparatus according to claim 20, wherein

25. The substrate processing apparatus according to claim 24, wherein

26. The substrate processing apparatus according to claim 20, wherein

said flowmeter is a differential pressure flowmeter, and

said differential pressure flowmeter comprises

27. A liquid supply method for supplying a liquid, comprising the steps of:

a) storing a liquid supplied from a liquid supply source in a flexible chamber by expanding said flexible chamber to increase a volume of said flexible chamber in a pump mechanism; and

b) pumping out said liquid to a conduit by applying pressure to said flexible chamber to reduce said volume of said flexible chamber, wherein said step b) comprises

b1) measuring a flowrate of said liquid flowing through said conduit in a downstream side of said pump mechanism; and

b2) controlling pressure applied to said flexible chamber so that said flowrate of said liquid flowing through said conduit is adjusted to a predetermined flowrate on the basis of said flowrate measured in said step b1).

28. The liquid supply method according to claim 27, further comprising the steps of:

c) storing said liquid supplied from said liquid supply source in another flexible chamber by expanding said another flexible chamber to increase a volume of said another flexible chamber in another pump mechanism; and

d) pumping out said liquid to said conduit by applying pressure to said another flexible chamber to reduce said volume of said another flexible chamber, wherein said step d) comprises

d1) measuring a flowrate of said liquid flowing through said conduit in a downstream side of said another pump mechanism; and

d2) controlling pressure applied to said another flexible chamber so that said flowrate of said liquid flowing through said conduit is adjusted to said predetermined flowrate on the basis of said flowrate measured in said step d1), wherein

said step a) and said step d) are performed almost concurrently,

said step b) and said step c) are performed almost concurrently, and

said step a) and said step d), and said step b) and said step c) are performed alternately.

29. The liquid supply method according to claim 28, wherein

said step b) starts before said step d) ends, and said step d) starts before said step b) ends.