Method for extracting organic solvent

Abstract

To provide a technology for separating pure water and an organic solvent from a mixed liquid while suppressing a replacement frequency of a separation membrane.SOLUTION: The method for extracting an organic solvent related to the technology disclosed in the present specification includes the steps of: discharging a mixed liquid of water and an organic solvent from a substrate processing apparatus; detecting a cleanliness degree indicating the amount of impurities contained in the mixed liquid; comparing the cleanliness degree with a first threshold value; performing dehydration from the mixed liquid by bringing at least a part of a separation membrane into contact with the mixed liquid and extracting the organic solvent; and reducing impurities in the mixed liquid prior to the dehydration when the cleanliness degree is less than the first threshold value.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The technology disclosed in the present specification relates to a technology for concentrating an organic solvent. [Background technology]

[0002] Typical substrate processing includes chemical processing in which a chemical solution is discharged onto the substrate, a rinse processing in which the chemical solution is rinsed with pure water, and an IPA processing in which the pure water is replaced with an organic solvent such as IPA (isopropyl alcohol) liquid (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2017-41505 Summary of the Invention [Problem to be solved by the invention]

[0004] In IPA treatment, a mixture of pure water and IPA liquid (organic waste liquid) is discharged, but to reduce the environmental load, it is desirable to separate (dehydrate) the pure water and IPA liquid.

[0005] On the other hand, when dehydration is performed using a separation membrane, impurities in the mixed liquid may clog the separation membrane, making it necessary to replace the separation membrane frequently.

[0006] The technology disclosed in this specification has been made in consideration of the problems described above, and is a technology for dehydrating a mixed liquid using a separation membrane while reducing the frequency of replacement of the separation membrane. Unless otherwise specified, the "mixed liquid" described in this specification refers to a mixed liquid of IPA (organic solvent) and water, a mixed liquid of IPA (organic solvent) and pure water, or a mixed liquid of IPA (organic solvent) and ultrapure water. [Means for solving the problem]

[0007] An organic solvent extraction method, which is a first aspect of the technology disclosed in the present specification, includes the steps of: discharging a mixed liquid of water and an organic solvent from a substrate processing apparatus; detecting a cleanliness level indicating the amount of impurities contained in the mixed liquid; comparing the cleanliness level with a first threshold value; dehydrating the mixed liquid by contacting at least a portion of a separation membrane to extract the organic solvent; and, if the cleanliness level is less than the first threshold value, reducing the impurities in the mixed liquid prior to the dehydration. The organic solvent extraction method according to the second aspect of the technology disclosed in the present specification is related to the organic solvent extraction method according to the first aspect, in which the separation membrane is permeable to the water but not to the organic solvent. An organic solvent extraction method that is a third aspect of the technology disclosed in the present specification is related to the organic solvent extraction method that is the second aspect, in which the separation membrane has a plurality of pores, each of which is permeable to the water but impermeable to the organic solvent, the first threshold value is determined based on the amount of impurities, and if the cleanliness is less than the first threshold value, the amount of impurities in the mixed liquid is reduced prior to the dehydration to reduce clogging of the pores in the separation membrane with the impurities. An organic solvent extraction method according to a fourth aspect of the technology disclosed in the present specification is related to the organic solvent extraction method according to the third aspect, and the first threshold value is determined based on the amount and size of the impurities. An organic solvent extraction method that is a fifth aspect of the technology disclosed in the present specification is related to the organic solvent extraction method that is the fourth aspect, and the impurities are particles and metal elements in the mixed liquid. The organic solvent extraction method according to a sixth aspect of the technology disclosed in the present specification is related to the organic solvent extraction method according to any one of the first to fifth aspects, wherein the organic solvent is isopropyl alcohol. An organic solvent extraction method according to a seventh aspect of the technology disclosed in the present specification is related to the organic solvent extraction method according to any one of the first to fifth aspects, in which the separation membrane is a zeolite membrane. An organic solvent extraction method, which is an eighth aspect of the technology disclosed in the present specification, is related to any one of the organic solvent extraction methods of the first to fifth aspects, and further includes a step of discharging the organic solvent onto a substrate after reducing the impurities in the organic solvent extracted by the separation membrane. The organic solvent extraction method according to a ninth aspect of the technology disclosed in the present specification is related to any one of the organic solvent extraction methods according to the first to fifth aspects, and further includes a step of storing the organic solvent extracted by the separation membrane. An organic solvent extraction method according to a tenth aspect of the technology disclosed in the present specification is related to any one of the organic solvent extraction methods according to the first to fifth aspects, and further includes a step of heating the mixed liquid before contacting the mixed liquid with the separation membrane. [Effects of the Invention]

[0008] According to at least the first aspect of the technology disclosed in the present specification, when the cleanliness of the mixed liquid is less than a first threshold, the mixed liquid can be dehydrated while reducing the frequency of replacing the separation membrane by reducing impurities in the mixed liquid before the mixed liquid is dehydrated.

[0009] Furthermore, objects, features, aspects, and advantages associated with the technology disclosed herein will become more apparent from the detailed description and accompanying drawings set forth below. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a plan view schematically illustrating an example of a substrate processing apparatus. [Figure 2] FIG. 2 is a side view schematically illustrating an example of a processing unit. [Figure 3] 2 is a diagram showing a schematic view of an example of a first storage box 50a and a second storage box 50b. FIG. [Figure 4] FIG. 10 is a diagram showing the experimental results of the relationship between the change in IPA concentration and the temperature in a mixed liquid of IPA liquid and pure water, in which the proportion of IPA liquid is 70 wt %. [Figure 5]10 is a flowchart showing an example of an operation in the first storage box 50a. [Figure 6] 10A and 10B are diagrams illustrating an example of the operation of the first storage box 50a and the second storage box 50b. [Figure 7] 10A and 10B are diagrams illustrating an example of the operation of the first storage box 50a and the second storage box 50b. [Figure 8] 10A and 10B are diagrams showing modified examples of the first storage box 50a and the second storage box 50b. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, embodiments will be described with reference to the accompanying drawings. In the following embodiments, detailed features are shown for the purpose of explaining the technology, but these are merely examples and are not necessarily essential features for enabling the embodiments to be implemented.

[0012] The drawings are schematic, and for the sake of convenience, components may be omitted or simplified as appropriate. The relative sizes and positions of components shown in different drawings are not necessarily accurately depicted and may be changed as appropriate. Hatching may also be used in drawings such as plan views that are not cross-sectional views to facilitate understanding of the embodiments.

[0013] In the following description, the same components are denoted by the same reference numerals, and their names and functions are also the same. Therefore, detailed descriptions of them may be omitted to avoid duplication.

[0014] Furthermore, in the description given in this specification, when a certain component is described as "comprising," "including," or "having," unless otherwise specified, this is not an exclusive expression that excludes the presence of other components.

[0015] Furthermore, although ordinal numbers such as "first" or "second" may be used in the descriptions in this specification, these terms are used for convenience to facilitate understanding of the contents of the embodiments, and the contents of the embodiments are not limited to the order that may result from these ordinal numbers.

[0016] Furthermore, in the description provided in this specification, terms that indicate specific positions or directions, such as "top," "bottom," "left," "right," "side," "bottom," "front," or "back," may be used, but these terms are used for convenience to facilitate understanding of the contents of the embodiments and have no relation to the positions or directions when the embodiments are actually implemented.

[0017] Furthermore, in the description of the present specification, when "the upper surface of ..." or "the lower surface of ..." is used, it is intended to include not only the upper surface or lower surface of the target component itself, but also a state in which another component is formed on the upper surface or lower surface of the target component. For example, when it is described as "B provided on the upper surface of A," it does not preclude another component "C" from being interposed between A and B.

[0018] <Embodiment> A substrate processing apparatus 100 according to this embodiment will be described with reference to Fig. 1. Fig. 1 is a plan view schematically showing an example of the substrate processing apparatus 100.

[0019] The substrate processing apparatus 100 is a so-called single-wafer processing apparatus that processes substrates W to be processed one by one. The substrates W to be processed by the substrate processing apparatus 100 are, for example, semiconductor substrates. The shape of the substrates W to be processed is, for example, a disk shape. Substrates to be processed include, for example, semiconductor wafers, glass substrates for liquid crystal display devices, substrates for flat panel displays (FPDs) such as organic electroluminescence (EL) display devices, substrates for optical disks, substrates for magnetic disks, substrates for magneto-optical disks, glass substrates for photomasks, ceramic substrates, substrates for field emission displays (i.e., FEDs), and substrates for solar cells.

[0020] The substrate processing apparatus 100 includes a load port 1, an indexer robot 2, a main transport robot 3, a processing unit 4, a first storage box 50a, a second storage box 50b, and a control unit 6.

[0021] The load port 1 is an interface for loading and unloading substrates W into and from a carrier C, which is a type of storage container that stores multiple substrates. For example, multiple load ports 1 (three in the example shown in the figure) are provided. The multiple load ports 1 are, for example, arranged in a horizontal row. The carrier C may be of a type that stores substrates W in an enclosed space (for example, a FOUP (Front Opening Unified Pod), a SMIF (Standard Mechanical Interface) pod, etc.), or may be of a type that exposes substrates W to the outside air (for example, an OC (Open Cassette), etc.).

[0022] The indexer robot 2 is a transport device that transports substrates W. As an example, the indexer robot 2 is a horizontal articulated robot that includes a pair of hands 21 that hold substrates W and arms 22 connected to each hand 21. The indexer robot 2 also includes a drive mechanism (not shown) for rotating each hand 21 and bending and extending, rotating, and raising and lowering each arm 22. The indexer robot 2 transports substrates W between a carrier C placed on the load port 1 and the main transport robot 3. That is, the indexer robot 2 accesses the carrier C placed on the load port 1 to perform an unloading operation (i.e., an operation of removing a substrate W accommodated in the carrier C with the hand 21) and a loading operation (i.e., an operation of placing a substrate W held by the hand 21 into the carrier C). The indexer robot 2 also accesses a transfer position 40 to transfer substrates W between the indexer robot 2 and the main transport robot 3.

[0023] The main transport robot 3 is a transport device that transports substrates W. As an example, the main transport robot 3 is a horizontal articulated robot that includes a pair of hands 31 that hold substrates W and arms 32 connected to each hand 31. The main transport robot 3 also includes a drive mechanism (not shown) for rotating each hand 31 and bending and extending, rotating, and raising and lowering each arm 32. The main transport robot 3 transports substrates W between the indexer robot 2 and each processing unit 4. That is, the main transport robot 3 accesses the transfer position 40 to transfer substrates W to and from the indexer robot 2. The main transport robot 3 also accesses the processing unit 4 to perform a load operation (i.e., an operation of loading the substrate W held by the hand 31 into the processing unit 4) and an unload operation (i.e., an operation of unloading the substrate W from the processing unit 4 with the hand 31).

[0024] The processing units 4 perform predetermined processing on the substrates W using processing liquids (e.g., chemical liquids, rinse liquids, and IPA liquids). Here, for example, a plurality of (e.g., three) processing units 4 stacked vertically form a tower, and a plurality of such towers (four in the illustrated example) are provided so as to surround the main transport robot 3. The specific configuration of the processing units 4 will be described later.

[0025] In the first storage box 50a, the organic solvent (IPA liquid in this embodiment) mixed with pure water is recovered from the processing unit 4, and the recovered organic solvent is concentrated and purified before being supplied to the second storage box 50b and further to the processing unit 4. The supplied organic solvent can be reused for substrate processing. As an example, a first storage box 50a may be provided in one-to-one correspondence with each of a plurality of towers, and each first storage box 50a may recover and supply IPA liquid to each processing unit 4 included in the corresponding tower. The specific configuration inside the first storage box 50a will be described later.

[0026] The control unit 6 controls the operation of each part of the substrate processing apparatus 100 (the load port 1, the indexer robot 2, the main transport robot 3, the processing unit 4, and each part in the first storage box 50a). The control unit 6 is configured, for example, by a general computer having electric circuits. As an example, the control unit 6 is configured to include a CPU (Central Processor Unit) as a central processing unit that performs various arithmetic processing (data processing), a ROM (Read Only Memory) in which basic programs and the like are stored, a RAM (Random Access Memory) used as a work area when the CPU performs predetermined processing (data processing), a storage device configured by a non-volatile storage device such as a flash memory or a hard disk drive, and a bus line connecting these components to each other. A program that defines the processing to be executed by the control unit 6 may be stored in the storage device or the RAM. In this case, for example, the CPU may execute the program, thereby controlling each part of the substrate processing apparatus 100 with the control unit 6, and the processing defined by the program may be executed in the substrate processing apparatus 100. In other words, the CPU may execute the program, thereby realizing a circuit in the control unit 6 that performs the processing defined by the program. However, part or all of the control performed by the control unit 6 (part or all of the circuitry realized by the control unit 6) may be executed (realized) by hardware such as a dedicated logic circuit.

[0027] <Processing unit> The processing unit 4 will be described with reference to Fig. 2. Fig. 2 is a side view schematically showing an example of the processing unit 4.

[0028] <Processing unit configuration> The processing unit 4 performs a predetermined process on the substrate W using a processing liquid (e.g., a chemical liquid, a rinse liquid, and an IPA liquid). The rinse liquid is, for example, water, pure water, or ultrapure water. The processing unit 4 includes, for example, a spin chuck 41, a cup 42, and a nozzle 43. The spin chuck 41, the cup 42, and the nozzle 43 are housed in a processing chamber 44.

[0029] The spin chuck 41 holds the substrate W in a horizontal position (the thickness direction of the substrate W is aligned with the up-down direction (vertical direction)) and rotates the substrate W around an axis (rotation axis) A extending vertically through the center of its main surface. Specifically, the spin chuck 41 includes, for example, a spin base 411. The spin base 411 is a disk-shaped member and is positioned with its thickness aligned with the up-down direction. A plurality of chuck pins 412 are provided on the upper surface of the spin base 411. The plurality of chuck pins 412 are arranged at equal intervals along a circumference corresponding to the periphery of the substrate W. A link mechanism (not shown) that moves the plurality of chuck pins 412 between an abutment position and an release position is connected to the plurality of chuck pins 412. The "abutment position" is a position where the chuck pins 412 abut (contact) with the periphery of the substrate W. The "release position" is a position where the chuck pins 412 are spaced apart from the periphery of the substrate W. When each of the chuck pins 412 is positioned in the abutment position, the substrate W is held (chucked) in a horizontal position above the spin base 411. When each of the chuck pins 412 is positioned in the release position, the substrate W is released from its hold. The link mechanism switches the positions of the chuck pins 412 in response to instructions from the control unit 6. That is, the timing of holding the substrate W, the timing of releasing the substrate W, and the like are controlled by the control unit 6. The spin base 411 is connected to a spin motor 414 via a shaft unit 413 that is provided coaxially with the rotation axis A. The shaft unit 413 and the spin motor 414 are housed in a cover 415. The spin motor 414 rotates the shaft unit 413 about the rotation axis A. This causes the spin base 411, and ultimately the substrate W held above it, to rotate about the rotation axis A. The spin motor 414 rotates the spin base 411 in response to instructions from the control unit 6. That is, the controller 6 controls the rotation speed of the spin base 411 (and thus the substrate W), the timing at which the rotation starts, the timing at which the rotation ends, and the like.

[0030] The cup 42 receives the processing liquid discharged from the substrate W held and rotated by the spin chuck 41. Specifically, the cup 42 includes, for example, a cylindrical guide portion 421 arranged coaxially with the rotation axis A, an inclined portion 422 connected to the upper end of the guide portion 421 and tapering in diameter as it extends upward (approaching the radially inner side of the spin chuck 41), and a liquid receiving portion 423 connected to the lower end of the guide portion 421 and forming an upwardly opening annular groove. The liquid receiving portion 423 is provided with cup-side recovery pipes (specifically, for example, a cup-side recovery pipe (not shown) for the chemical liquid and a cup-side recovery pipe 424 for IPA) for recovering the liquid received therein. A cup lifting mechanism 425 is connected to the cup 42, which lifts and lowers the cup 42 between a lower position and an upper position. The "lower position" is a position where the upper end of the cup 42 (specifically, the upper end of the inclined portion 422) is located below the substrate W held by the spin chuck 41. The "upper position" is a position where the upper end of the cup 42 is located above the substrate W held by the spin chuck 41. The cup lifting mechanism 425 lifts and lowers the cup 42 in response to an instruction from the control unit 6. That is, the position of the cup 42 is controlled by the control unit 6.

[0031] The nozzles 43 eject a processing liquid toward the upper surface of the substrate W held by the spin chuck 41. Here, for example, a separate nozzle 43 is provided for each type of processing liquid. That is, a nozzle 43 that ejects a chemical liquid (hereinafter also referred to as a "chemical liquid nozzle 43a"), a nozzle 43 that ejects a rinse liquid (hereinafter also referred to as a "rinse liquid nozzle 43b"), and a nozzle 43 that ejects an IPA liquid (hereinafter also referred to as an "IPA nozzle 43c") are provided.

[0032] The chemical nozzle 43a discharges a chemical solution toward the upper surface of the substrate W held by the spin chuck 41. The chemical nozzle 43a is connected to a chemical solution supply source 433a via a chemical solution pipe 432a having a chemical solution valve 431a inserted therein. When the chemical solution valve 431a is opened, the chemical solution is supplied to the chemical solution nozzle 43a through the chemical solution pipe 432a, and the chemical solution is discharged from the chemical solution nozzle 43a. The chemical solution valve 431a is opened and closed in response to an instruction from the control unit 6. That is, the discharge timing of the chemical solution from the chemical solution nozzle 43a is controlled by the control unit 6. The chemical solution is, for example, hydrofluoric acid. However, the chemical solution is not limited to hydrofluoric acid, and may be a solution containing at least one of sulfuric acid, acetic acid, nitric acid, hydrochloric acid, hydrofluoric acid, phosphoric acid, ammonia water, hydrogen peroxide water, organic acid (e.g., citric acid, oxalic acid, etc.), organic alkali (e.g., TMAH: tetramethylammonium hydroxide, etc.), surfactant, and corrosion inhibitor.

[0033] The rinse liquid nozzle 43b discharges a rinse liquid toward the upper surface of the substrate W held on the spin chuck 41. The rinse liquid nozzle 43b is connected to a rinse liquid supply source 433b via a rinse liquid pipe 432b in which a rinse liquid valve 431b is inserted. When the rinse liquid valve 431b is opened, the rinse liquid is supplied to the rinse liquid nozzle 43b through the rinse liquid pipe 432b, and the rinse liquid is discharged from the rinse liquid nozzle 43b. The rinse liquid valve 431b is opened or closed in response to an instruction from the control unit 6.

[0034] The IPA nozzle 43c ejects IPA liquid (i.e., a liquid containing IPA as a main component) toward the upper surface of the substrate W held on the spin chuck 41. The IPA nozzle 43c is connected to the second housing box 50b via an IPA pipe 432c having an IPA valve 431c inserted therein. When the IPA valve 431c is opened, the IPA liquid is supplied to the IPA nozzle 43c through the IPA pipe 432c, and the IPA liquid is ejected from the IPA nozzle 43c. The IPA valve 431c is opened and closed in response to an instruction from the control unit 6. That is, the ejection timing of the IPA liquid from the IPA nozzle 43c is controlled by the control unit 6.

[0035] At least one of the chemical liquid nozzle 43a, the rinse liquid nozzle 43b, and the IPA nozzle 43c may be connected to a nozzle moving mechanism that moves the nozzle between a processing position and a retracted position. The "processing position" is a position where the processing liquid ejected from the nozzles 43a, 43b, and 43c is supplied to the substrate W held on the spin chuck 41. The "retracted position" is a position where the nozzles 43a, 43b, and 43c are located outside (radially outward from) the periphery of the substrate W held on the spin chuck 41 when viewed from above. In this case, the nozzle moving mechanism moves the nozzles 43a, 43b, and 43c in response to an instruction from the control unit 6. That is, the positions of the nozzles 43a, 43b, and 43c are controlled by the control unit 6.

[0036] <Operation of the processing unit> The following describes an example of the operation of the processing unit 4. The operation performed in the processing unit 4 is performed under the control of the control unit 6 (i.e., the control unit 6 controls the chuck pin 412, the spin motor 414, the cup lifting mechanism 425, the chemical liquid valve 431a, the rinse liquid valve 431b, the IPA valve 431c, etc.).

[0037] When the substrate W is carried into the processing chamber 44 by the main transport robot 3, the spin chuck 41 holds the substrate W. Then, the spin chuck 41 starts to rotate.

[0038] In this state, the chemical valve 431a is opened. Then, the chemical nozzle 43a discharges the chemical toward the upper surface of the substrate W, which is held and rotated by the spin chuck 41. This causes the chemical to be supplied to the entire upper surface of the substrate W, and the substrate W is treated with the chemical (chemical treatment process). For example, when hydrofluoric acid is used as the chemical, foreign matter such as particles is removed from the substrate W. During the chemical treatment process, the cup 42 is positioned in the upper position. Therefore, the chemical that has splashed around the substrate W is received by the cup 42. Specifically, the chemical that has splashed around the substrate W is received by the inclined portion 422, guided downward by the guide portion 421, and collected in the liquid receiving portion 423. The chemical received by the cup 42 (i.e., the chemical collected in the liquid receiving portion 423) is collected through a cup-side recovery pipe for the chemical (not shown).

[0039] When a predetermined time has elapsed since the discharge of the chemical liquid started, the chemical liquid valve 431a is closed. This stops the discharge of the chemical liquid from the chemical liquid nozzle 43a. Subsequently, the rinse liquid valve 431b is opened. This causes the rinse liquid to be discharged from the rinse liquid nozzle 43b toward the upper surface of the substrate W, which is held and rotated by the spin chuck 41. As a result, the rinse liquid is supplied to the entire upper surface of the substrate W, and the chemical liquid adhering to the substrate W is washed away by the rinse liquid (rinse processing step). The cup 42 is positioned in the upper position even during the rinse processing step. Therefore, the chemical liquid and rinse liquid splashed around the substrate W are received by the cup 42. The chemical liquid and rinse liquid received by the cup 42 are collected through a cup-side recovery pipe for the chemical liquid (not shown).

[0040] When a predetermined time has elapsed since the discharge of the rinse liquid started, the rinse liquid valve 431b is closed. This stops the discharge of the rinse liquid from the rinse liquid nozzle 43b. Subsequently, the IPA valve 431c is opened. This causes the IPA liquid to be discharged from the IPA nozzle 43c toward the upper surface of the substrate W held and rotated by the spin chuck 41. As a result, the IPA liquid is supplied to the entire upper surface of the substrate W, and the rinse liquid adhering to the substrate W is replaced with the IPA liquid (IPA supplying step). The cup 42 is also positioned in the upper position during the IPA supplying step. Therefore, the mixture of the rinse liquid and IPA liquid splashed around the substrate W is received by the cup 42. The rinse liquid and IPA liquid received by the cup 42 are collected through the cup-side recovery pipe 424 for IPA.

[0041] After a predetermined time has elapsed since the start of the supply of IPA liquid, the IPA valve 431c is closed. This stops the IPA liquid from being discharged from the IPA nozzle 43c. At this stage, the rinse liquid on the substrate W is completely replaced with the IPA liquid, and a liquid film of the IPA liquid is formed covering the entire upper surface of the substrate W. Next, the spin chuck 41 starts rotating at high speed. This causes the substrate W to rotate at high speed, and the IPA liquid on the substrate W is scattered around the substrate W by centrifugal force (spin drying process). The cup 42 remains in the upper position while the substrate W is being rotated at high speed. Therefore, the IPA liquid splashed around the substrate W is received by the cup 42. The IPA liquid received by the cup 42 is collected through the cup-side recovery pipe 424 for IPA.

[0042] When a predetermined time has elapsed since the high-speed rotation of the spin chuck 41 began, the rotation of the spin chuck 41 is stopped. At this stage, the IPA liquid has been removed from the substrate W, and the substrate W has been dried. The dried substrate W is then transported out of the processing chamber 44 by the main transport robot 3.

[0043] This completes the series of processes for one substrate W. In the processing unit 4, the series of operations described above is repeated, so that a plurality of substrates W are processed one by one.

[0044] <First storage box, second storage box> The configuration of the first storage box 50a and the second storage box 50b will be described with reference to Fig. 3. Fig. 3 is a diagram schematically showing an example of the first storage box 50a and the second storage box 50b.

[0045] The first storage box 50a accommodates a recovery tank 502, a purification tank 504, and a waste liquid tank 1002. The second storage box 50b accommodates a supply tank 506. As an example, the recovery tank 502 and the purification tank 504 are accommodated in the first storage box 50a, and the supply tank 506 is accommodated in the second storage box 50b. As an example, the first storage box 50a is arranged outside the outer wall 100a of the substrate processing apparatus 100 (for example, below (underground) the clean room in which the substrate processing apparatus 100 is installed), and the second storage box 50b is arranged inside the outer wall 100a of the substrate processing apparatus 100 (FIG. 1).

[0046] <Recovery tank> The recovery tank 502 is connected to the cup 42 through a branched recovery pipe 512. That is, the recovery tank 502 is connected to one end of the recovery pipe 512 (the end of a recovery pipe 512a branched from the recovery pipe 512), and the cup 42 (specifically, a cup-side recovery pipe 424 connected to the cup 42) is connected to the other end of the recovery pipe 512. In this example, the recovery pipe 512 is connected to the cups 42 provided in each of the multiple processing units 4 belonging to the same tower. A valve 511 is inserted in the recovery pipe 512a branched from the recovery pipe 512. The mixture of the IPA liquid and the rinse liquid discharged from the substrate processing apparatus (processing unit 4) is recovered from the cup 42, passes through the recovery pipe 512, and is then stored in the recovery tank 502.

[0047] Furthermore, recovery tank 502 is connected to purification circulation pipe 538 through branched second liquid supply pipe 552. That is, recovery tank 502 is connected to one end of second liquid supply pipe 552 (the end of second liquid supply pipe 552a branched from second liquid supply pipe 552), and purification circulation pipe 538 is connected to the other end of second liquid supply pipe 552. As an example, the other end of second liquid supply pipe 552 is connected to a position in purification circulation pipe 538 between temperature sensor 548 and metal filter 544a. A valve 554a is inserted in second liquid supply pipe 552a.

[0048] A circulation pipe (spin-dry circulation pipe 514) is connected to the recovery tank 502. The spin-dry circulation pipe 514 forms a circulation path through which the liquid stored in the recovery tank 502 flows out of the recovery tank 502 and returns to the recovery tank 502. A drainage tank 1002 is also connected to the recovery tank 502 via a pipe 1003. The drainage tank 1002 stores the liquid drained from the recovery tank 502 when a valve 1003A is opened under the control of the control unit 6.

[0049] In addition, a first measuring instrument 517a and a second measuring instrument 517b are interposed in the recovery pipe 512. The first measuring instrument 517a measures the number of particles (particle count) and the size of the particles in the mixed liquid flowing through the recovery pipe 512. The particles are, for example, organic residues such as resist. The first measuring instrument 517a is, for example, an optical particle detector, and detects the amount and size of particles based on scattered light from particles present in the mixed liquid flowing through the recovery pipe 512. The second measuring instrument 517b is an instrument that detects the amount and type of metal elements in the fluid flowing through the recovery pipe 512 by inductively coupled plasma mass spectrometry or the like. The first measuring instrument 517a and the second measuring instrument 517b detect the cleanliness of the mixed liquid flowing through the recovery pipe 512. For example, the cleanliness of the mixed liquid may be determined based on the amount of particles or the amount of metal elements, or based on the type of metal elements or the size of the particles. Information on the cleanliness measured by the first measuring instrument 517a and the second measuring instrument 517b may be sent to the control unit 6 and compared with a first threshold value described below. The first threshold value is a value set in the control unit 6, for example, based on the performance of the separation membrane (the allowable limit value of the amount of impurities).

[0050] A dehydrator 516 is inserted into the dehydration circulation pipe 514. The dehydrator 516 includes a separation membrane 516a that separates the pure water from a mixture of IPA and pure water, and a dehydration housing 516b that houses the separation membrane 516a. The mixture is dehydrated by bringing at least a portion of the separation membrane 516a into contact with the mixture. A discharge pipe 515 is connected to the dehydrator 516 for discharging the pure water (DIW) separated from the mixture.

[0051] The separation membrane 516a has a plurality of pores, and extracts the IPA liquid from the mixed liquid by dehydrating it by taking advantage of the difference in size between IPA molecules and water molecules. For example, by using a separation membrane with a plurality of pores that allow water molecules to pass through but not IPA molecules, it is possible to dehydrate the mixed liquid. The separation membrane 516a is, for example, a zeolite membrane made of zeolite. Zeolite is, for example, a tetrahedral structure consisting of a basic unit (e.g., (SiO4)4- and (AlO4) 5- The separation membrane 516a separates water molecules from IPA molecules by utilizing the difference in size between the two (allowing only water molecules to pass through), and is expected to be used when the proportion of IPA in the liquid is 50 wt% or more. Zeolite membranes are permeable to water molecules but not to IPA molecules.

[0052] The separation membrane 516a is not limited to a zeolite membrane. For example, the separation membrane 516a may be an organic separation membrane. The organic separation membrane is an organic membrane formed, for example, of polyvinyl alcohol, chitosan, polyimide, or the like. The separation membrane 516a may also be a CNT (carbon nanotube) separation membrane. The CNT separation membrane is a membrane obtained by adding carbon nanotubes to a membrane such as polyamide. The separation membrane 516a may also be formed from a two-dimensional material. The two-dimensional material is a material composed of one layer of atoms, specifically, molybdenum sulfide (MoS2), a composite atomic layer compound of an early transition metal (titanium, vanadium, etc.) and a light element (carbon or nitrogen), or the like. The separation membrane 516a may also be formed from an MOF (metal organic frameworks) material or a carbon material (for example, graphene, graphene oxide, etc.).

[0053] In the dehydration circulation pipe 514, a valve 522, a dehydration-side liquid pump 518, a temperature regulator 524 having cooling and heating capabilities, a dehydrator 516, and a valve 520 are arranged in this order from the recovery tank 502 along the dehydration circulation pipe 514. Note that a heater may be provided instead of the temperature regulator 524.

[0054] Here, the degree to which separation membrane 516a separates water (pure water) from IPA (separation performance) increases as the temperature of the mixed liquid increases. In this embodiment, the mixed liquid is heated by temperature regulator 524 before contacting separation membrane 516a. The temperature of the mixed liquid is set to, for example, 70°C. FIG. 4 shows experimental results of the relationship between the change in IPA concentration and temperature for a mixed liquid of IPA and pure water, with an IPA content of 70 wt%. In FIG. 4, the vertical axis represents the change in IPA concentration [wt%], and the horizontal axis represents the temperature [degC] of the mixed liquid. FIG. 4 shows the change in IPA concentration at each temperature when the mixed liquid is circulated for one hour through dehydration circulation pipe 514 shown in FIG. 3, with the volume of the mixed liquid being 1000 ml. The separation membrane 516a is assumed to be a zeolite membrane, and the IPA in the mixed liquid comes into contact with separation membrane 516a.

[0055] As shown in the example in Figure 4, the higher the temperature of the circulating mixed liquid, the greater the change in IPA concentration.

[0056] Various sensors are inserted in the dehydration circulation pipe 514. For example, a concentration sensor 526 that measures the concentration of the organic solvent (here, for example, IPA liquid) in the mixed liquid flowing through the dehydration circulation pipe 514, a flow rate sensor 532 (flow meter) that measures the flow rate of the mixed liquid flowing through the dehydration circulation pipe 514, a pressure sensor 528 that detects the pressure of the mixed liquid flowing through the dehydration circulation pipe 514, a temperature sensor 530 that detects the temperature of the mixed liquid flowing through the dehydration circulation pipe 514, and the like are inserted in the dehydration circulation pipe 514.

[0057] The concentration sensor 526 is inserted, for example, downstream of the dehydrator 516 and upstream of the collection tank 502. The flow rate sensor 532 is inserted, for example, downstream of the collection tank 502 and upstream of the dehydration-side liquid feed pump 518. The pressure sensor 528 is inserted, for example, downstream of the dehydration-side liquid feed pump 518 and upstream of the temperature regulator 524. The temperature sensor 530 is inserted, for example, upstream of the dehydrator 516 and downstream of the temperature regulator 524.

[0058] <Septic tank> The purification tank 504 is connected to the cup 42 through a branched recovery pipe 512. That is, the purification tank 504 is connected to one end of the recovery pipe 512 (the end of the recovery pipe 512b branching from the recovery pipe 512), and the cup 42 (specifically, the cup-side recovery pipe 424 connected to the cup 42) is connected to the other end of the recovery pipe 512. Here, for example, the recovery pipe 512 is connected to the cups 42 provided in each of the multiple processing units 4 belonging to the same tower.

[0059] Furthermore, purification tank 504 is connected to dehydration circulation pipe 514 through branched first liquid supply pipe 534. That is, purification tank 504 is connected to one end of first liquid supply pipe 534 (the end of first liquid supply pipe 534a branched from first liquid supply pipe 534), and dehydration circulation pipe 514 is connected to the other end of first liquid supply pipe 534. As an example, the other end of first liquid supply pipe 534 is connected to a position in dehydration circulation pipe 514 between temperature sensor 530 and dehydrator 516. A valve 536a is inserted in first liquid supply pipe 534a.

[0060] A circulation pipe (purification circulation pipe 538) is connected to the purification tank 504. The purification circulation pipe 538 forms a circulation path in which the liquid stored in the purification tank 504 flows out of the purification tank 504 and returns to the purification tank 504.

[0061] In the purification circulation pipe 538, a purification-side liquid transfer pump 540, a temperature regulator 546, a metal filter 544a, a particle filter 544b, a particle detector 543, and a valve 542 are arranged in this order from the purification tank 504 along the purification circulation pipe 538. An air vent pipe 539 is connected to the metal filter 544a and the particle filter 544b.

[0062] The particle detector 543 is, for example, an optical detector, and is a device that samples the concentrated mixed liquid flowing through the purification circulation pipe 538 and detects particles present in the sampled concentrated mixed liquid based on a response wavelength obtained by measuring the concentrated mixed liquid. The metal filter 544a is a filter that removes metal elements from the fluid flowing through the purification circulation pipe 538. The particle filter 544b is a filter that removes particles from the fluid flowing through the purification circulation pipe 538. The metal filter 544a and the particle filter 544b are made of, for example, polytetrafluoroethylene (PTFE). The arrangement order of the metal filter 544a and the particle filter 544b may be reversed from the order shown in FIG. 3.

[0063] The temperature regulator 546 is a device having both cooling and heating capabilities. The temperature regulator 546 may be, for example, a device that performs electronic cooling using a Peltier element (a so-called electronic cooling / heating unit).

[0064] Furthermore, measuring instruments 549a and 549b are inserted in purification circulation piping 538 at positions downstream of particle filter 544b and upstream of valve 542. Measuring instrument 549a, like first measuring instrument 517a, is an instrument that measures the number of particles (particle count) in the fluid flowing through purification circulation piping 538. Measuring instrument 549b, like second measuring instrument 517b, is an instrument that measures the amount of metal elements in the fluid flowing through purification circulation piping 538 by inductively coupled plasma mass spectrometry or the like.

[0065] Various sensors are inserted in the purification circulation pipe 538. For example, a temperature sensor 548 that detects the temperature of the fluid flowing through the purification circulation pipe 538, a pressure sensor 550 that detects the pressure of the fluid flowing through the purification circulation pipe 538, and the like are inserted in the purification circulation pipe 538. The temperature sensor 548 is inserted, for example, at a position upstream of the metal filter 544a and downstream of the temperature regulator 546. The pressure sensor 550 is inserted, for example, at a position downstream of the purification-side liquid feed pump 540 and upstream of the temperature regulator 546.

[0066] <Supply Tank> Supply tank 506 is connected to dehydration circulation pipe 514 and purification circulation pipe 538 through third liquid supply pipe 553. That is, supply tank 506 is connected to one end of third liquid supply pipe 553, and dehydration circulation pipe 514 and purification circulation pipe 538 are connected to the other end of third liquid supply pipe 553.

[0067] The other end of the third liquid feed pipe 553 is connected to the branched first liquid feed pipe 534 and the branched second liquid feed pipe 552. Specifically, the other end of the third liquid feed pipe 553 is connected to the first liquid feed pipe 534b branched from the first liquid feed pipe 534 and the second liquid feed pipe 552b branched from the second liquid feed pipe 552. A valve 536b is inserted in the first liquid feed pipe 534b. A valve 554b is inserted in the second liquid feed pipe 552b. A valve 555 is inserted in the third liquid feed pipe 553.

[0068] As an example, the other end of the third liquid supply pipe 553 is connected to the dehydration circulation pipe 514 at a position downstream of the temperature sensor 530 and upstream of the dehydrator 516, and is connected to the purification circulation pipe 538 at a position upstream of the metal filter 544a and downstream of the temperature regulator 546.

[0069] The supply tank 506 is connected to an IPA supply source 558 through an IPA supply pipe 556. That is, one end of the IPA supply pipe 556 is connected to the supply tank 506, and the other end of the IPA supply pipe 556 is connected to the IPA supply source 558. The IPA supply source 558 is a supply source of unused IPA liquid (e.g., IPA liquid with a concentration of 99.8 wt % or more) that has never been supplied to a substrate W. An IPA supply valve 560 is inserted into the IPA supply pipe 556.

[0070] The supply tank 506 is connected to the IPA nozzle 43c through a fourth liquid supply pipe 562. That is, the supply tank 506 is connected to one end of the fourth liquid supply pipe 562, and the IPA nozzle 43c (specifically, the IPA pipe 432c connected to the IPA nozzle 43c) is connected to the other end of the fourth liquid supply pipe 562. Here, for example, the fourth liquid supply pipe 562 is connected to the IPA nozzles 43c provided in each of the multiple processing units 4 belonging to the same tower.

[0071] A pump (supply-side liquid feed pump 564) is inserted in the fourth liquid feed pipe 562. A filter 566 is inserted in the fourth liquid feed pipe 562 at a position downstream of the supply-side liquid feed pump 564. A temperature regulator 568 is inserted in the fourth liquid feed pipe 562 at a position upstream of the filter 566 and downstream of the supply-side liquid feed pump 564. The filter 566 is, for example, a filter that removes metal elements from the fluid flowing through the fourth liquid feed pipe 562, or a filter that removes particles from the fluid flowing through the fourth liquid feed pipe 562. The filter 566 is made of, for example, polytetrafluoroethylene (PTFE).

[0072] Various sensors are inserted in the fourth liquid feed pipe 562. For example, a temperature sensor 570 that detects the temperature of the fluid flowing through the fourth liquid feed pipe 562, a pressure sensor 572 that detects the pressure of the fluid flowing through the fourth liquid feed pipe 562, and the like are inserted in the fourth liquid feed pipe 562. The temperature sensor 570 is inserted, for example, at a position upstream of the filter 566 and downstream of the temperature regulator 568. The pressure sensor 572 is inserted, for example, at a position downstream of the supply-side liquid feed pump 564 and upstream of the temperature regulator 568.

[0073] <Operation in the first storage box 50a> An example of the operation in the first storage box 50a will be described with reference to Fig. 5. Here, Fig. 5 is a flowchart showing an example of the operation in the first storage box. The operation performed in the first storage box 50a is performed under the control of the control unit 6 (i.e., the control unit 6 controls the valve 511, the dehydration-side liquid supply pump 518, the valve 520, the valve 522, the temperature regulator 524, the valve 536a, the valve 536b, the valve 542, the valve 554a, the valve 554b, the valve 555, etc.).

[0074] In the operation in the first storage box 50a, first, the first measuring instrument 517a measures the number of particles in the mixed liquid discharged from the substrate processing apparatus and flowing through the recovery pipe 512. In addition, the second measuring instrument 517b measures the number of metal elements in the mixed liquid flowing through the recovery pipe 512 (step ST1 in FIG. 5). The first measuring instrument 517a is an instrument that measures the number of particles (particle count) in the mixed liquid flowing through the recovery pipe 512. The second measuring instrument 517b is an instrument that measures the amount of metal elements in the fluid flowing through the recovery pipe 512 by inductively coupled plasma mass spectrometry or the like. The mixed liquid flowing through the recovery pipe 512 is a liquid generated by mixing IPA liquid, an organic solvent after being used in substrate processing, with pure water that was also used in substrate processing. For example, the proportion of IPA liquid in the mixed liquid is 50 wt % or more.

[0075] The control unit 6 determines whether the cleanliness level calculated using at least one of the number of particles measured by the first measuring instrument 517a and the amount of metal elements measured by the second measuring instrument 517b is equal to or greater than a predetermined first threshold value (step ST2 in FIG. 5). That is, the cleanliness level is compared with the first threshold value.

[0076] If the determined cleanliness is equal to or greater than the first threshold value (if the cleanliness is high), the mixed liquid is dehydrated in a dehydration path passing through the dehydration circulation pipe 514 (step ST4 in FIG. 5). Here, a high cleanliness corresponds to a small number of measured particles or a small amount of metal elements, and conversely, a low cleanliness corresponds to a large number of measured particles or a large amount of metal elements.

[0077] On the other hand, if the determined cleanliness is lower than the first threshold value (if the cleanliness is low), the mixed liquid is purified in a purification path passing through the purification circulation pipe 538 (step ST3 in FIG. 5). Thereafter, the mixed liquid is dehydrated in a dehydration path passing through the dehydration circulation pipe 514 (step ST4 in FIG. 5).

[0078] Next, it is determined whether or not the mixed liquid is used for substrate processing (step ST5 in FIG. 5). Here, being used for substrate processing corresponds to, for example, discharging the dehydrated mixed liquid onto the upper surface of the substrate W.

[0079] When the dehydrated mixed liquid is used for substrate processing, the dehydrated mixed liquid is purified in the purification path (step ST6 in FIG. 5). The dehydrated mixed liquid contains a higher concentration of IPA liquid than the mixed liquid before dehydration. The dehydrated mixed liquid is then stored in the supply tank 506 and discharged onto the upper surface of the substrate W in each processing chamber 44 (step ST7 in FIG. 5).

[0080] On the other hand, if the mixed liquid is not used for substrate processing, the mixed liquid is drained from the recovery tank 502 to the drain tank 1002 (step ST8 in FIG. 5).

[0081] If the measurement in step ST1 shows that the cleanliness of the mixed liquid is equal to or greater than the first threshold value, valve 511 is opened and valve 513 is closed to store the mixed liquid in recovery tank 502. On the other hand, if the cleanliness of the mixed liquid is less than the first threshold value, valve 511 is closed and valve 513 is opened to store the mixed liquid in purification tank 504.

[0082] If the cleanliness of the mixed liquid is less than the first threshold, the number of metal elements or particles passing through separation membrane 516a in dehydrator 516 increases, causing greater damage to separation membrane 516a (i.e., deterioration of separation membrane 516a progresses). Therefore, if the cleanliness of the mixed liquid is less than the first threshold, it is effective to first circulate the mixed liquid through purification circulation piping 538 to increase the cleanliness of the mixed liquid.

[0083] Fig. 6 is a diagram showing an example of the operation of the first storage box 50a and the second storage box 50b. In the example shown in Fig. 6, valve 511 is opened and valve 513 is closed, and the mixed liquid is stored in the recovery tank 502. In Fig. 6, valves painted black indicate that they are in the open state, and valves that are not painted black indicate that they are in the closed state. The open / closed states of the valves are different between Fig. 3 and Fig. 6.

[0084] In the recovery tank 502, the mixed liquid is circulated through a dehydration circulation pipe 514, and the mixed liquid is dehydrated in a dehydrator 516 provided in the dehydration circulation pipe 514. That is, the mixed liquid is passed through a separation membrane 516a in the dehydrator 516, whereby the IPA liquid, which is the organic solvent in the mixed liquid, is separated from the pure water. The concentration of the dehydrated mixed liquid is measured appropriately by a concentration sensor 526, and the mixed liquid is repeatedly circulated through the dehydration circulation pipe 514 and dehydrated until the IPA concentration of the mixed liquid reaches the desired concentration. Meanwhile, the pure water separated from the mixed liquid is discharged from a discharge pipe 515.

[0085] When the mixed liquid is to be used for substrate processing, the valve 536a is opened and the valve 536b is closed to store the mixed liquid in the purification tank 504 (see FIG. 6). On the other hand, when the mixed liquid is not to be used for substrate processing, the valve 536a is closed and the valve 536b is closed to drain the mixed liquid from the recovery tank 502 to the drain tank 1002.

[0086] Fig. 7 is a diagram showing an example of the operation of the first storage box 50a and the second storage box 50b. In the example shown in Fig. 7, valve 511 is closed and valve 513 is open to store the mixed liquid in the purification tank 504. In Fig. 7, valves painted black indicate that they are in the open state, and valves that are not painted black indicate that they are in the closed state. The open and closed states of the valves are different between Fig. 3 and Fig. 7.

[0087] In purification tank 504, the mixed liquid is circulated through purification circulation piping 538, and purified by metal filter 544a and particle filter 544b provided in purification circulation piping 538. That is, by passing the mixed liquid through metal filter 544a and particle filter 544b, metal elements and particles in the mixed liquid are removed. The number of particles in the purified mixed liquid is measured as appropriate by measuring instrument 549a. In addition, the amount of metal elements is measured as appropriate by measuring instrument 549b, and the mixed liquid is repeatedly purified by circulating through purification circulation piping 538 until the cleanliness of the mixed liquid reaches a desired value.

[0088] Second liquid feed pipe 552, which branches off from purification circulation pipe 538, further branches off into second liquid feed pipe 552a and second liquid feed pipe 552b. After the above purification, if the dehydration process in dehydration circulation pipe 514 has not yet been performed, valve 554a is opened and valve 554b is closed, and the mixed liquid is stored in recovery tank 502 via second liquid feed pipe 552a (see FIG. 7). After storing the mixed liquid in recovery tank 502, the mixed liquid is circulated through dehydration circulation pipe 514, and the mixed liquid is dehydrated by dehydrator 516 provided in dehydration circulation pipe 514.

[0089] Here, the mixed liquid that was first circulated through the purification circulation pipe 538 because the cleanliness measured by the first measuring instrument 517a and the second measuring instrument 517b was below the first threshold value, and then circulated through the dehydration circulation pipe 514 and concentrated, needs to be purified again when used for substrate processing. However, the second purification circulation pipe is a pipe different from the first purification circulation pipe 538 (see FIG. 8 described below). This is because the mixed liquid before dehydration remains in the first purification circulation pipe 538, which may reduce the IPA concentration in the mixed liquid.

[0090] The filter diameters (size of openings) of metal filter 544a and particle filter 544b passing through the first circulation in purification circulation pipe 538 and the metal filter and particle filter passing through the second circulation in purification circulation pipe 538 may be the same or different. Because the amount of impurities in the mixed liquid differs before and after circulation in dehydration circulation pipe 514, for example, by making the filter diameters of metal filter 544a and particle filter 544b in the first circulation in purification circulation pipe 538 larger (coarser) than the filter diameters of the metal filter and particle filter in the second circulation in purification circulation pipe 538, clogging of the filters can be suppressed and impurities in the mixed liquid can be effectively removed (described later in FIG. 8).

[0091] Fig. 8 is a diagram showing modified examples of the first storage box and the second storage box. Fig. 8 shows the first storage box 150a. In the first storage box 150a, the first liquid supply pipe 534a is connected to the purification tank 1504, and the mixed liquid purified through the purification circulation pipe 538 and the purification tank 504 is sent to the recovery tank 502 through the second liquid supply pipe 552a. Then, the mixed liquid concentrated through the recovery tank 502 and the dehydration circulation pipe 514 is sent to the purification tank 1504 through the first liquid supply pipe 534a.

[0092] A circulation pipe (purification circulation pipe 1538) is connected to the purification tank 1504. The purification circulation pipe 1538 forms a circulation path in which the liquid stored in the purification tank 1504 flows out of the purification tank 1504 and circulates back to the purification tank 1504.

[0093] In the purification circulation pipe 1538, a purification side liquid transfer pump 1540, a temperature regulator 1546, a metal filter 544c, a particle filter 544d, a particle detector 1543, and a valve 1542 are arranged in this order from the purification tank 1504 along the purification circulation pipe 1538. An air vent pipe 1539 is connected to the metal filter 544c and the particle filter 544d.

[0094] The particle detector 1543 is, for example, an optical detector that samples the concentrated mixed liquid flowing through the purification circulation pipe 1538 and detects particles present in the sampled concentrated mixed liquid based on a response wavelength obtained by measuring the concentrated mixed liquid. The metal filter 544c is a filter that removes metal elements from the fluid flowing through the purification circulation pipe 1538 and has a smaller filter diameter than the metal filter 544a of the first purification circulation pipe 538. The particle filter 544d is a filter that removes particles from the fluid flowing through the purification circulation pipe 1538 and has a smaller filter diameter than the particle filter 544b of the first purification circulation pipe 538. The metal filter 544c and the particle filter 544d are made of, for example, polytetrafluoroethylene (PTFE). The arrangement order of the metal filter 544c and the particle filter 544d may be reversed from the order shown in FIG. 3.

[0095] The temperature regulator 1546 is a device having cooling and heating capabilities. The temperature regulator 1546 may be, for example, a device that performs electronic cooling using a Peltier element (a so-called electronic cooling / heating unit).

[0096] Furthermore, measuring instruments 1549a and 1549b are inserted into purification circulation pipe 1538 at positions downstream of particle filter 544d and upstream of valve 1542. Measuring instrument 1549a, like first measuring instrument 517a, is an instrument that measures the number of particles (particle count) in the fluid flowing through purification circulation pipe 1538. Measuring instrument 1549b, like second measuring instrument 517b, is an instrument that measures the amount of metal elements in the fluid flowing through purification circulation pipe 1538 by inductively coupled plasma mass spectrometry or the like.

[0097] Various sensors are inserted in the purification circulation pipe 1538. For example, a temperature sensor 1548 that detects the temperature of the fluid flowing through the purification circulation pipe 1538, a pressure sensor 1550 that detects the pressure of the fluid flowing through the purification circulation pipe 1538, and the like are inserted in the purification circulation pipe 1538. The temperature sensor 1548 is inserted, for example, at a position upstream of the metal filter 544c and downstream of the temperature regulator 1546. The pressure sensor 1550 is inserted, for example, at a position downstream of the purification side liquid feed pump 1540 and upstream of the temperature regulator 1546.

[0098] After the above purification, valve 1554 is opened and the mixed liquid is stored in supply tank 506 via second liquid supply pipe 1552 and third liquid supply pipe 553 .

[0099] 8 is not limited to the case where circulation in the purification circulation pipe is performed once each before and after circulation in the dehydration circulation pipe 514. In other words, it is also applicable to the case where circulation in the purification circulation pipe 538 is performed only once before circulation in the dehydration circulation pipe 514 and circulation in the purification circulation pipe 1538 is not performed after circulation in the dehydration circulation pipe 514, or the case where circulation in the purification circulation pipe 1538 is performed only once after circulation in the dehydration circulation pipe 514 and circulation in the purification circulation pipe 538 is not performed before circulation in the dehydration circulation pipe 514.

[0100] <Modifications of the above-described embodiments> In the embodiments described above, the dimensions, shapes, relative positional relationships, and implementation conditions of each component may be described, but these are merely examples in all aspects and are not limiting.

[0101] Thus, numerous variations and equivalents not shown are contemplated within the scope of the technology disclosed herein, including, for example, the modification, addition, or omission of at least one component.

[0102] Furthermore, in at least one of the embodiments described above, when a material name or the like is stated without being specifically specified, unless a contradiction arises, it is assumed that the material in question includes other additives, such as alloys. [Explanation of symbols]

[0103] 6 Control Unit 43a Chemical nozzle 43b Rinse liquid nozzle 43c IPA nozzle 502 Recovery Tank 504 Purification Tank 506 Supply Tank 516 Dehydrator 516a Separation membrane 566 filters

Claims

1. Discharging the mixed liquid of water and organic solvent from the substrate processing apparatus; detecting a cleanliness level indicating the amount of impurities contained in the mixed solution; comparing the cleanliness level to a first threshold; a step of contacting the mixed liquid with at least a part of a separation membrane to remove water from the mixed liquid and extract the organic solvent; If the cleanliness is less than the first threshold, reducing the impurities in the mixed liquor prior to the dehydration. Organic solvent extraction method.

2. The organic solvent extraction method according to claim 1, the separation membrane is permeable to the water but impermeable to the organic solvent; Organic solvent extraction method.

3. The organic solvent extraction method according to claim 2, the separation membrane has a plurality of pores, each of which is permeable to the water but impermeable to the organic solvent; the first threshold is determined based on the amount of the impurity; If the cleanliness is less than the first threshold, the amount of impurities in the mixed liquid is reduced prior to the dehydration, thereby reducing clogging of the pores of the separation membrane with the impurities. Organic solvent extraction method.

4. The organic solvent extraction method according to claim 3, the first threshold is determined based on the amount and size of the impurity; Organic solvent extraction method.

5. The organic solvent extraction method according to claim 4, The impurities are particles and metal elements in the mixed solution. Organic solvent extraction method.

6. The organic solvent extraction method according to any one of claims 1 to 5, The organic solvent is isopropyl alcohol. Organic solvent extraction method.

7. The organic solvent extraction method according to any one of claims 1 to 5, The separation membrane is a zeolite membrane. Organic solvent extraction method.

8. The organic solvent extraction method according to any one of claims 1 to 5, The method further includes a step of discharging the organic solvent onto a substrate after reducing the impurities in the organic solvent extracted by the separation membrane. Organic solvent extraction method.

9. The organic solvent extraction method according to any one of claims 1 to 5, The method further comprises a step of storing the organic solvent extracted by the separation membrane. Organic solvent extraction method.

10. The organic solvent extraction method according to any one of claims 1 to 5, The method further comprises a step of heating the mixture before contacting the mixture with the separation membrane. Organic solvent extraction method.

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