Organic solvent recovery device, substrate processing device, and organic solvent recovery method

Abstract

To provide a technique capable of separating water from a mixed liquid with high reliability and high efficiency.SOLUTION: An organic solvent recovery device includes a recovery pipe 51, a first dehydrator 60, and a second dehydrator 70. A mixed liquid of an organic solvent and water discharged from a processing unit 4 for processing a substrate W flows through the recovery pipe 51. The first dehydrator 60 includes a first separation membrane 62c having an applicable range of solvent concentration, and includes a first membrane separator 62 that separates water from the mixed liquid having a solvent concentration equal to or higher than a concentration lower limit value that is a lower limit value of the applicable range to increase the solvent concentration of the mixed liquid. The second dehydrator 70 is provided at a stage preceding the first dehydrator 60, separates water from the mixed liquid discharged through the recovery pipe 51, raises the solvent concentration of the mixed liquid to a concentration lower limit value or more, and supplies the mixed liquid having the solvent concentration equal to or higher than the concentration lower limit value to the first dehydrator 60.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present disclosure relates to an organic solvent recovery apparatus, a substrate processing apparatus, and an organic solvent recovery method. [Background technology]

[0002] Patent Document 1 discloses an IPA recovery system that recovers aqueous IPA (isopropyl alcohol) discharged from a processing unit that processes substrates. The IPA recovery system includes a storage tank, a circulation pipe, a pump, a dehydration unit, and a filter. The storage tank is supplied with aqueous IPA from the processing unit. The circulation pipe is connected to the storage tank and returns the aqueous IPA from the storage tank to the storage tank. A pump is provided in the circulation pipe and transports the aqueous IPA from the upstream end to the downstream end of the circulation pipe. A filter is provided in the circulation pipe and removes foreign matter from the aqueous IPA. A dehydration unit is provided in the circulation pipe and removes moisture from the aqueous IPA.

[0003] The recovery system circulates the wet IPA through a circulation path that includes a storage tank and circulation piping. This circulation causes the wet IPA to pass through a filter and a spin-drying unit. This increases the IPA concentration of the circulating wet IPA and reduces the amount of foreign matter in the wet IPA. In other words, this circulation results in clean wet IPA with a high IPA concentration being stored in the storage tank. This wet IPA in the storage tank is then supplied back to the processing unit. This reduces the amount of IPA that is wasted. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2017-41505 Summary of the Invention [Problem to be solved by the invention]

[0005] A membrane separator including a separation membrane can be used as a dehydration unit for separating water from a mixed liquid. A separation membrane is a membrane that allows water to pass through while blocking most of the organic solvent. Such a membrane separator can separate water from a mixed liquid with high energy efficiency compared to separation methods such as distillation. However, when the concentration of the organic solvent in the mixed liquid is low, flowing the mixed liquid into the membrane separator can cause problems in the membrane separator.

[0006] Therefore, an object of the present disclosure is to provide a technology that can separate water from a mixed liquid with high reliability and high efficiency. [Means for solving the problem]

[0007] A first aspect is an organic solvent recovery apparatus comprising: a recovery pipe through which a mixture of organic solvent and water discharged from a processing unit for processing substrates flows; a first dehydrator including a first membrane separator having a first separation membrane having an applicable range of solvent concentrations, which separates water from the mixture having a solvent concentration equal to or greater than a lower limit concentration value that is the lower limit of the applicable range, thereby increasing the solvent concentration of the mixture; and a second dehydrator located upstream of the first dehydrator, which separates water from the mixture discharged through the recovery pipe, thereby increasing the solvent concentration of the mixture to equal to or greater than the lower limit concentration value, and supplies the mixture having a solvent concentration equal to or greater than the lower limit concentration value to the first dehydrator.

[0008] A second aspect is an organic solvent recovery apparatus according to the first aspect, wherein the second dehydrator includes a first liquid supply pipe through which the mixed liquid flows toward the first dehydrator, the first dehydrator includes a second liquid supply pipe through which the mixed liquid flows toward a supply tank for supply to the processing unit, and the first membrane separator is connected to the downstream end of the first liquid supply pipe and the upstream end of the second liquid supply pipe.

[0009] A third aspect is the organic solvent recovery apparatus according to the first aspect, wherein the first dehydrator includes a concentration tank that stores the mixed liquid, a first circulation pipe that is connected to the concentration tank and in which the first membrane separator is provided, and a liquid delivery section that is provided in the first circulation pipe.

[0010] A fourth aspect is the organic solvent recovery apparatus according to any one of the first to third aspects, wherein the second dehydrator includes at least one of a distillation column and an ultrasonic atomization separator.

[0011] A fifth aspect is an organic solvent recovery apparatus according to any one of the first to fourth aspects, wherein the second dehydrator includes a second membrane separator having a second separation membrane, the lower limit of the solvent concentration range of the second separation membrane is less than the lower limit of the solvent concentration of the first separation membrane, and the separation constant of the first separation membrane is higher than the separation constant of the second separation membrane.

[0012] A sixth aspect is the organic solvent recovery apparatus according to the fifth aspect, wherein the second dehydrator includes a concentration tank that stores the mixed liquid flowing in from the recovery pipe, a second circulation pipe connected to the concentration tank and provided with the second membrane separator, and a liquid delivery section provided in the second circulation pipe.

[0013] A seventh aspect is the organic solvent recovery apparatus according to the sixth aspect, further comprising a switching valve unit, wherein the first dehydrator includes a first circulation pipe connected to the concentration tank, the first circulation pipe includes a common circulation pipe provided with the liquid delivery unit and a first individual pipe provided with the first membrane separator, the second circulation pipe includes the common circulation pipe and a second individual pipe provided with the second membrane separator, and the switching valve unit switches between a first circulation state in which the mixed liquid circulates through the concentration tank and the first circulation pipe and a second circulation state in which the mixed liquid circulates through the concentration tank and the second circulation pipe.

[0014] An eighth aspect is the organic solvent recovery apparatus according to the seventh aspect, further comprising a control unit that causes the switching valve unit to select the second circulation state when the solvent concentration of the mixed liquid is a second value that is less than the concentration lower limit value of the first separation membrane, and that causes the switching valve unit to select the first circulation state when the solvent concentration of the mixed liquid is a first value that is equal to or greater than the concentration lower limit value.

[0015] A ninth aspect is an organic solvent recovery apparatus according to any one of the first to sixth aspects, further comprising: a recovery destination switching unit that switches between a second dehydration state in which the mixed liquid discharged from the processing unit is supplied to the second dehydrator and a first dehydration state in which the mixed liquid discharged from the processing unit is supplied to the first dehydrator, bypassing the second dehydrator; and a control unit that causes the recovery destination switching unit to select the second dehydration state when the solvent concentration of the mixed liquid is a second value that is less than the concentration lower limit of the first separation membrane, and that causes the recovery destination switching unit to select the first dehydration state when the solvent concentration of the mixed liquid is a first value that is equal to or greater than the concentration lower limit.

[0016] A tenth aspect is an organic solvent recovery apparatus according to the ninth aspect, comprising a memory unit storing recipe information indicating the processing content of the substrate by the processing unit, and the control unit calculating the solvent concentration of the mixed liquid discharged from the processing unit based on the recipe information.

[0017] An eleventh aspect is the organic solvent recovery apparatus according to the tenth aspect, wherein the processing unit includes a substrate holding part that holds and rotates the substrate, a discharge part that sequentially discharges pure water and organic solvent onto a main surface of the substrate held by the substrate holding part, and a cylindrical cup that surrounds the substrate holding part and collects liquid splashed from the periphery of the substrate, the upstream end of the recovery pipe is connected to the cup, the recipe information includes settings for the pure water flow rate and discharge time of the pure water to be discharged onto the substrate, the solvent flow rate and discharge time of the organic solvent to be discharged onto the substrate, and the rotation speed of the substrate, the memory part stores correspondence information that indicates a correspondence between the rotation speed and a pure water film amount, which is the amount of pure water on the main surface of the substrate, and the control part determines the pure water film amount based on the rotation speed of the substrate specified based on the recipe information and the correspondence information, and calculates the solvent concentration of the mixed liquid discharged from the processing unit based on the pure water film amount, the time integral value of the pure water flow rate, and the time integral value of the solvent flow rate.

[0018] A twelfth aspect is an organic solvent recovery device according to the ninth aspect, further comprising a concentration sensor for measuring the solvent concentration of the mixed liquid, and the control unit controls the recovery destination switching unit based on the solvent concentration of the mixed liquid measured by the concentration sensor.

[0019] A thirteenth aspect is the organic solvent recovery apparatus according to any one of the first to sixth aspects, further comprising a recovery destination switching unit and a control unit that controls the recovery destination switching unit, wherein the recovery piping includes a plurality of cup-side recovery pipes connected to a plurality of the processing units, a common recovery pipe connected to downstream ends of the plurality of cup-side recovery pipes, a first dehydration pipe that connects the downstream end of the common recovery pipe to the first dehydrator, and a second dehydration pipe that connects the downstream end of the common recovery pipe to the second dehydrator, and the recovery destination switching unit communicates the common recovery pipe with the first dehydrator through the first dehydration pipe. The control unit switches between a first dehydration state in which the mixed liquid is supplied to the first dehydrator bypassing the second dehydrator, and a second dehydration state in which the common recovery pipe is connected to the second dehydrator through the second dehydration pipe and the mixed liquid is supplied to the second dehydrator, and the control unit causes the recovery destination switching unit to select the first dehydration state when the solvent concentration of the mixed liquid flowing through the common recovery pipe is a first value that is equal to or greater than the concentration lower limit value of the first separation membrane, and causes the recovery destination switching unit to select the second dehydration state when the solvent concentration of the mixed liquid flowing through the common recovery pipe is a second value that is less than the concentration lower limit value.

[0020] A fourteenth aspect is a substrate processing apparatus, comprising the organic solvent recovery apparatus according to any one of the first to thirteenth aspects and the processing unit.

[0021] A fifteenth aspect is an organic solvent recovery method comprising a first step of separating water from a mixture of organic solvent and water discharged from a processing unit for processing substrates to increase the solvent concentration of the mixture, and a second step of separating water from the mixture using a first membrane separator including a first separation membrane having an applicable range of solvent concentrations after the first step to increase the solvent concentration of the mixture, wherein in the first step, the solvent concentration of the mixture is increased to or above a concentration lower limit value, which is the lower limit value of the applicable range of the first separation membrane. [Effects of the Invention]

[0022] According to the first, fourteenth, and fifteenth aspects, even if the mixed liquid discharged from the treatment unit has a low solvent concentration, the second dehydrator increases the solvent concentration of the mixed liquid to or above the lower limit of the first separation membrane. This allows the highly efficient first membrane separator to properly separate water from the mixed liquid. Therefore, the organic solvent recovery device can increase the solvent concentration of the mixed liquid with high reliability and high efficiency.

[0023] According to the second aspect, the mixed liquid from the first liquid feed pipe passes through the first membrane separator and is supplied to the supply tank through the second liquid feed pipe. Since the first dehydrator does not circulate the mixed liquid, the operation time of the first dehydrator can be shortened.

[0024] According to the third aspect, the size required for the first membrane separator can be reduced.

[0025] According to the fourth aspect, the second dehydrator has a very low lower limit of concentration, so that even if the mixed solution discharged from the treatment unit has a very low solvent concentration, the second dehydrator can increase the solvent concentration of the mixed solution to or above the lower limit of concentration of the first separation membrane.

[0026] According to the fifth aspect, the second dehydrator can separate water from a mixed liquid having a solvent concentration below the lower limit of the first separation membrane, thereby increasing the solvent concentration of the mixed liquid. After the second membrane separator increases the solvent concentration of the mixed liquid to or above the lower limit of the first separation membrane, the first membrane separator including the first separation membrane with a high separation constant further increases the solvent concentration of the mixed liquid. This allows the organic solvent recovery device to increase the solvent concentration of the mixed liquid more efficiently.

[0027] According to the sixth aspect, the size required for the second membrane separator can be reduced.

[0028] According to the seventh aspect, the liquid delivery section is shared by the first circulation pipe and the second circulation pipe, so that the manufacturing cost can be reduced.

[0029] According to the eighth aspect, when the solvent concentration of the mixed liquid in the concentration tank is low, the mixed liquid is circulated through the second circulation pipe. Therefore, the second membrane separator, which has a low concentration lower limit, separates water from the mixed liquid to increase the solvent concentration. Then, when the solvent concentration increases, the mixed liquid is circulated through the first circulation pipe. Therefore, the first membrane separator, which has a high separation constant, separates water from the mixed liquid to increase the solvent concentration. Therefore, the organic solvent recovery device can increase the solvent concentration of the mixed liquid with high reliability and high efficiency.

[0030] According to the ninth and thirteenth aspects, when the solvent concentration of the mixed liquid from the processing unit is high, the second dehydrator does not operate. This makes it possible to avoid power consumption by the second dehydrator. On the other hand, when the solvent concentration of the mixed liquid from the processing unit is low, the second dehydrator operates. This makes it possible for the second dehydrator to supply the first dehydrator with a mixed liquid having a solvent concentration equal to or higher than the lower limit of the concentration of the first separation membrane.

[0031] According to the tenth aspect, there is no need to provide a concentration sensor, and therefore manufacturing costs can be reduced.

[0032] According to the eleventh aspect, the solvent concentration can be calculated with high accuracy.

[0033] According to the twelfth aspect, the solvent concentration can be obtained with high accuracy. [Brief explanation of the drawings]

[0034] [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] FIG. 2 is a diagram schematically illustrating an example of an organic solvent recovery unit according to the first embodiment. [Figure 4] FIG. 2 is a diagram schematically illustrating an example of a specific configuration of an organic solvent recovery unit. [Figure 5] 10 is a flowchart showing an example of the operation of the organic solvent recovery unit. [Figure 6] FIG. 10 is a diagram schematically illustrating an example of a second dehydrator according to a second embodiment. [Figure 7] FIG. 10 is a diagram schematically illustrating an example of an organic solvent recovery unit according to a third embodiment. [Figure 8] FIG. 10 is a diagram schematically illustrating a first example of a more specific configuration of an organic solvent recovery unit according to a third embodiment. [Figure 9] FIG. 10 is a diagram schematically illustrating a second example of a more specific configuration of an organic solvent recovery unit according to the third embodiment. [Figure 10] FIG. 10 is a diagram schematically illustrating a first example of a substrate processing apparatus according to a fourth embodiment. [Figure 11] 10 is a flowchart showing an example of the operation of the organic solvent recovery unit according to the fourth embodiment. [Figure 12] FIG. 10 is a diagram schematically illustrating an example of a processing unit according to a fourth embodiment. [Figure 13] FIG. 2 is a diagram schematically illustrating an example of the state of a processing unit in each step of Table 1. [Figure 14] 10 is a graph showing an example of the distance from the center of the substrate to each position on the substrate and the thickness of the liquid film of pure water at each position. [Figure 15] FIG. 1 is a diagram schematically illustrating an example of the state of a processing unit in each step of Table 2. [Figure 16] 10 is a graph showing an example of the distance from the center of the substrate to each position on the substrate and the thickness of the liquid film at each position. [Figure 17] 10 is a flowchart illustrating an example of an operation of a concentration estimation unit. [Figure 18] FIG. 10 is a diagram schematically illustrating a second example of a substrate processing apparatus according to a fourth embodiment. [Figure 19] FIG. 10 is a diagram schematically illustrating an example of a substrate processing apparatus according to a fifth embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0035] Hereinafter, the embodiments will be described in detail with reference to the drawings. In the drawings, the dimensions and numbers of parts are exaggerated or simplified as necessary for ease of understanding. Parts having similar configurations and functions are designated by the same reference numerals, and duplicate explanations will be omitted below.

[0036] 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.

[0037] Furthermore, in the following description, even if ordinal numbers such as "first" or "second" are used, these terms are used for convenience to facilitate understanding of the contents of the embodiments, and are not limited to the order that may result from these ordinal numbers.

[0038] When expressions indicating relative or absolute positional relationships (e.g., "in one direction," "along one direction," "parallel," "orthogonal," "center," "concentric," "coaxial," etc.) are used, unless otherwise specified, the expressions not only strictly represent the positional relationship but also represent a state in which there is a relative displacement in terms of angle or distance within a range in which tolerance or equivalent functionality is obtained. When expressions indicating an equal state (e.g., "identical," "equal," "homogeneous," etc.) are used, the expressions not only represent a state in which there is strict quantitative equality but also represent a state in which there is a difference in which tolerance or equivalent functionality is obtained, unless otherwise specified. When expressions indicating a shape (e.g., "rectangular shape" or "cylindrical shape," etc.) are used, the expressions not only represent a geometrically strict shape but also represent a shape with, for example, irregularities or chamfers within a range in which equivalent effects are obtained, unless otherwise specified. When the expressions "comprise," "include," "have," "includes," "includes," or "have" are used to describe one component, the expressions are not exclusive expressions that exclude the presence of other components. When the phrase "at least one of A, B, and C" is used, the phrase includes A only, B only, C only, any two of A, B, and C, and all of A, B, and C.

[0039] First Embodiment <1. Substrate processing equipment> A substrate processing apparatus 100 according to an embodiment will be described with reference to Fig. 1. Fig. 1 is a plan view schematically illustrating an example of the substrate processing apparatus 100.

[0040] 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 in 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.

[0041] The substrate processing apparatus 100 includes a load port 1, an indexer robot 2, a main transport robot 3, a processing unit 4, an organic solvent recovery unit 5, and a control unit 6.

[0042] 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.).

[0043] 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, 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 to transfer substrates W to and from the main transport robot 3.

[0044] 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, 31 that hold the substrates W, and an arm 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 a transfer position to transfer substrates W to and from the indexer robot 2. The main transport robot 3 also accesses a 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).

[0045] The processing units 4 perform predetermined processing on the substrates W using processing liquids (e.g., chemical liquids, rinse liquids, and IPA). 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.

[0046] The organic solvent recovery section 5 recovers the organic solvent from the processing unit 4, purifies the recovered organic solvent, and supplies it back to the processing unit 4. As an example, an organic solvent recovery section 5 may be provided in one-to-one correspondence with each of a plurality of towers, and each organic solvent recovery section 5 may recover and supply the organic solvent to each processing unit 4 included in the corresponding tower. The specific configuration of the organic solvent recovery section 5 will be described later.

[0047] The control unit 6 controls the operation of each part (load port 1, indexer robot 2, main transport robot 3, processing unit 4, and organic solvent recovery unit 5) of the substrate processing apparatus 100. The control unit 6 is configured, for example, by a general computer having electrical 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 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.

[0048] <2. 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.

[0049] <2-1. Processing unit configuration> The processing unit 4 performs a predetermined process using a processing liquid (e.g., a chemical liquid, a rinse liquid, and IPA) on the substrate W. The processing unit 4 includes, for example, a spin chuck 41, which is an example of a substrate holding unit, a cup 42, and a discharge unit 430. The discharge unit 430 includes a nozzle 43. The spin chuck 41, the cup 42, and the nozzle 43 are housed in a processing chamber 44.

[0050] 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 that passes through the center of its main surface and extends vertically. Specifically, the spin chuck 41 includes, for example, a spin base 411. The spin base 411 is a disk-shaped member and is positioned such that its thickness direction is 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 against 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 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 are controlled by the control unit 6.

[0051] The cup 42 has a cylindrical shape surrounding the spin chuck 41 and 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, 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, 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.

[0052] The discharge unit 430 (specifically, the nozzle 43) discharges the processing liquid toward the upper surface of the substrate W held on 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 discharges a chemical liquid (hereinafter also referred to as a "chemical liquid nozzle 43a"), a nozzle 43 that discharges a rinsing liquid (hereinafter also referred to as a "rinsing liquid nozzle 43b"), and a nozzle 43 that discharges IPA (hereinafter also referred to as an "IPA nozzle 43c") are provided.

[0053] 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.

[0054] 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 having a rinse liquid valve 431b interposed therein. 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 and closed in response to an instruction from the control unit 6. That is, the discharge timing of the rinse liquid from the rinse liquid nozzle 43b is controlled by the control unit 6. The rinse liquid is, for example, pure water (deionized water). However, the rinse liquid is not limited to pure water and may be any of carbonated water, electrolytic ionized water, hydrogen water, ozone water, and diluted hydrochloric acid water (for example, about 10 to 100 ppm).

[0055] The IPA nozzle 43c ejects IPA (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 organic solvent recovery unit 5 via an IPA pipe 432c having an IPA valve 431c inserted therein. When the IPA valve 431c is opened, IPA is supplied to the IPA nozzle 43c through the IPA pipe 432c, and the IPA 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 from the IPA nozzle 43c is controlled by the control unit 6.

[0056] 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.

[0057] <2-2. 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.).

[0058] 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.

[0059] 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).

[0060] 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).

[0061] 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 IPA 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, IPA is supplied to the entire upper surface of the substrate W, and the rinse liquid adhering to the substrate W is replaced with IPA (IPA supplying step). Even during the IPA supplying step, the cup 42 is positioned in the upper position. Therefore, the rinse liquid and IPA splashed around the substrate W are received by the cup 42. The rinse liquid and IPA received by the cup 42 are collected through the cup-side recovery pipe 424 for IPA.

[0062] After a predetermined time has elapsed since the start of the IPA supply, the IPA valve 431c is closed. This stops the IPA from being discharged from the IPA nozzle 43c. At this stage, the rinse liquid on the substrate W is completely replaced with IPA, and a liquid film of IPA 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 on the substrate W is scattered around the substrate W by centrifugal force (spin dry process). The cup 42 remains in the upper position while the substrate W is being rotated at high speed. Therefore, the IPA scattered around the substrate W is received by the cup 42. The IPA received by the cup 42 is collected through the cup-side recovery pipe 424 for IPA.

[0063] 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 has been removed from the substrate W, and the substrate W has been dried. The dried substrate W is then carried out of the processing chamber 44 by the main transport robot 3.

[0064] 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.

[0065] <3. Overview of the organic solvent recovery section 5 (organic solvent recovery device)> The configuration of the organic solvent recovery section 5 will be described with reference to Fig. 3. Fig. 3 is a diagram schematically illustrating an example of the organic solvent recovery section 5 according to the first embodiment. Below, an overview of the organic solvent recovery section 5 will first be described, and then each component of the organic solvent recovery section 5 will be described in detail.

[0066] The organic solvent recovery section 5 includes a first dehydrator 60 and a second dehydrator 70. The second dehydrator 70 is provided upstream of the first dehydrator 60. The downstream end of the recovery pipe 51 is connected to the second dehydrator 70. The recovery pipe 51 is also connected to the downstream end of each cup-side recovery pipe 424. A mixture of organic solvent and water discharged from the processing unit 4 flows through the recovery pipe 51. The organic solvent is, for example, an organic solvent that is more volatile than water or an organic solvent with low surface tension, such as IPA (isopropyl alcohol). The mixture is supplied (recovered) to the second dehydrator 70 through the recovery pipe 51. A buffer tank may be provided between the second dehydrator 70 and the processing unit 4. That is, the mixture discharged from the processing unit 4 may be temporarily stored in the buffer tank, and then the mixture may be supplied from the buffer tank to the second dehydrator 70 through the recovery pipe 51.

[0067] Here, it is assumed that the concentration of the organic solvent (hereinafter referred to as solvent concentration) in the mixed liquid discharged from the processing unit 4 is low. As an example, the solvent concentration in the mixed liquid discharged from the processing unit 4 is 30 wt % or less.

[0068] The second dehydrator 70 separates water from the mixed liquid to increase the solvent concentration of the mixed liquid. An example of a specific configuration of the second dehydrator 70 will be described in detail later. The second dehydrator 70 supplies the mixed liquid with the increased solvent concentration to the first dehydrator 60 through a first liquid feed pipe 78. An upstream end of the first liquid feed pipe 78 is connected to the second dehydrator 70, and a downstream end of the first liquid feed pipe 78 is connected to the first dehydrator 60.

[0069] The first dehydrator 60 includes a first membrane separator 62. The mixed liquid from the second dehydrator 70 flows into the first membrane separator 62. The first membrane separator 62 separates water from the mixed liquid, thereby further increasing the solvent concentration of the mixed liquid.

[0070] As shown in FIG. 3, the first membrane separator 62 includes a first mixture path 62a, a first water path 62b, and a first separation membrane 62c. The mixed liquid flows into the first mixture path 62a. The first separation membrane 62c separates the first mixture path 62a from the first water path 62b. The first separation membrane 62c allows the water in the mixed liquid to pass through and blocks most of the organic solvent. Some of the water in the mixed liquid that flows into the first mixture path 62a passes through the first separation membrane 62c and flows into the first water path 62b. As a result, the solvent concentration of the mixed liquid that has passed through the first mixture path 62a becomes higher than the solvent concentration of the mixed liquid immediately before flowing into the first mixture path 62a. The first dehydrator 60 uses the first membrane separator 62 to increase the solvent concentration of the mixed liquid to or above a predetermined reuse standard value. The reuse standard value is the solvent concentration that can be used in the treatment unit 4 and is set, for example, in advance. Hereinafter, the mixed liquid whose solvent concentration has been increased to or above the reuse standard value will also be referred to as the recycled liquid. It can also be said that the first dehydrator 60 separates water from the mixed liquid from the second dehydrator 70 to generate the recycled liquid.

[0071] The upstream end of a second liquid supply pipe 85 is connected to the first dehydrator 60, and the downstream end of the second liquid supply pipe 85 is connected to a supply tank Tk3 for supplying to the processing unit 4. The first dehydrator 60 supplies the reuse liquid to the supply tank Tk3 through the second liquid supply pipe 85. The mixed liquid in the supply tank Tk3 is supplied to the processing unit 4 again.

[0072] The first separation membrane 62c has an applicable solvent concentration range. In other words, the first separation membrane 62c can adequately separate water from a mixed solution having a solvent concentration within the applicable range. On the other hand, if a mixed solution having a solvent concentration below the lower limit of the applicable range flows into the first membrane separator 62, a malfunction may occur in the first separation membrane 62c. For example, the first membrane separator 62 may not be able to adequately separate water from the mixed solution. Alternatively, if the proportion of water molecules passing through the first separation membrane 62c exceeds the allowable value, the crystalline structure constituting the first separation membrane 62c may partially dissolve, resulting in a significantly shortened service life of the first separation membrane 62c. Hereinafter, the lower limit of the applicable solvent concentration range will be referred to as the concentration lower limit. As an example, the concentration lower limit of the first separation membrane 62c is 50 wt%.

[0073] In the first embodiment, the solvent concentration of the mixed liquid discharged from the processing unit 4 is less than the lower limit of the concentration of the first separation membrane 62c. The mixed liquid is supplied to the second dehydrator 70, which is located upstream of the first dehydrator 60. The lower limit of the concentration of the second dehydrator 70 is equal to or lower than the solvent concentration of the mixed liquid discharged from the processing unit 4. Therefore, the second dehydrator 70 can appropriately separate water from the mixed liquid discharged from the processing unit 4 and increase the solvent concentration of the mixed liquid. The second dehydrator 70 increases the solvent concentration of the mixed liquid to or above the lower limit of the concentration of the first separation membrane 62c. The second dehydrator 70 then supplies the separated mixed liquid to the first dehydrator 60.

[0074] Since the solvent concentration of the mixed liquid from the second dehydrator 70 is equal to or greater than the lower limit of the concentration of the first separation membrane 62c, the first dehydrator 60 can properly separate water from the mixed liquid using the first membrane separator 62. As a result, the first dehydrator 60 can properly produce recycled liquid.

[0075] As described above, the organic solvent recovery section 5 increases the solvent concentration in the mixed liquid discharged from the processing unit 4 to generate a reused liquid. This reused liquid is supplied again to the processing unit 4. In other words, the substrate processing apparatus 100 reuses the organic solvent in the mixed liquid discharged from the processing unit 4. This makes it possible to reduce the amount of organic solvent discarded, and to use the organic solvent more effectively. In other words, the organic solvent recovery section 5 contributes to saving liquid.

[0076] Moreover, in the first embodiment, the second dehydrator 70 first increases the solvent concentration of the mixed liquid from the treatment unit 4. Therefore, even if the solvent concentration of the mixed liquid from the treatment unit 4 is below the lower limit of the applicable range of the first separation membrane 62c, the second dehydrator 70 can increase the solvent concentration of the mixed liquid to or above the lower limit of the concentration of the first separation membrane 62c. Therefore, the first membrane separator 62 of the first dehydrator 60 can appropriately increase the solvent concentration of the mixed liquid. In other words, the reliability of the organic solvent recovery section 5 can be improved.

[0077] Furthermore, since the first dehydrator 60 separates water from the mixed liquid using the first membrane separator 62, the efficiency of the first dehydrator 60 is high. For example, the energy efficiency of the first dehydrator 60 is higher than the energy efficiency of other separation methods such as distillation. That is, in the first embodiment, after the second dehydrator 70 increases the solvent concentration of the mixed liquid to or above the lower limit concentration of the first separation membrane 62c, the first dehydrator 60 further increases the solvent concentration of the mixed liquid using the highly efficient first membrane separator 62.

[0078] Therefore, the organic solvent recovery unit 5 can increase the solvent concentration of the mixed liquid with higher reliability and higher efficiency. In addition, since the device size of the first membrane separator 62 is small, the organic solvent recovery unit 5 can be realized in a smaller size.

[0079] <3-1. Specific example of organic solvent recovery unit 5> 4 is a diagram schematically illustrating an example of a specific configuration of the organic solvent recovery unit 5. The organic solvent recovery unit 5 can be accommodated in a first storage box 50a (see FIG. 1). As an example, the first storage box 50a is disposed outside the outer wall 100a of the substrate processing apparatus 100 (for example, below (for example, downstairs) the clean room in which the substrate processing apparatus 100 is installed).

[0080] <3-1-1.Second dehydrator> 4, the second dehydrator 70 includes a distillation column 701 and a cooler 702. The downstream end of recovery piping 51 is connected to the distillation column 701, and the upstream end of steam piping 731 is connected to, for example, the upper part of the distillation column 701. The downstream end of steam piping 731 is connected to the cooler 702.

[0081] In the example of FIG. 4, a recovery valve 52 is inserted in the recovery pipe 51. When the control unit 6 opens the recovery valve 52, the mixed liquid from the processing unit 4 is supplied to the distillation column 701 through the recovery pipe 51. The distillation column 701 includes a heating unit (not shown) that heats the mixed liquid. The distillation column 701 separates water from the mixed liquid by distillation, utilizing the difference between the boiling points of the organic solvent and water. In this example, the boiling point of the organic solvent is lower than that of water, and the volatility of the organic solvent is higher than that of water. The organic solvent is, for example, IPA. The distillation column 701 vaporizes the mixed liquid and supplies the vapor containing a large amount of organic solvent to the upstream end of the steam pipe 731. The vapor flowing into the upstream end of the steam pipe 731 may contain not only the organic solvent but also water, but the solvent concentration is higher than the solvent concentration immediately before entering the distillation column 701. This vapor flows into the cooler 702 through the steam pipe 731. The bottom of distillation column 701 may be connected to the upstream end of a discharge pipe (not shown) for discharging water.

[0082] The upstream end of liquid piping 732 is also connected to cooler 702. Cooler 702 cools and condenses the vapor. Cooler 702 may have, for example, a heat exchanger. The vapor passes through the heat exchanger. Cooler 702 may have a heat pump-type cooling source that cools the heat exchanger, or may have a cooling source with a Peltier element. Heat is removed from the vapor by the heat exchanger, and the vapor is transformed into a liquid (i.e., a mixed liquid). This mixed liquid flows into the upstream end of liquid piping 732. The solvent concentration of this mixed liquid is higher than the solvent concentration of the mixed liquid immediately before distillation column 701.

[0083] As shown in FIG. 4, second dehydrator 70 may include multiple distillation columns 701 and multiple coolers 702. In the example of FIG. 4, pairs of distillation columns 701 and coolers 702 are connected in series. In the example of FIG. 4, distillation columns 701a and 701b are shown as distillation columns 701, and coolers 702a and 702b are shown as coolers 702. The downstream end of recovery piping 51 is connected to distillation column 701a, vapor piping 731 connects distillation column 701a and cooler 702a, and liquid piping 732 connects cooler 702a and distillation column 701b. Steam from distillation column 701a is condensed in cooler 702a to form a mixed liquid, and the mixed liquid from cooler 702a is supplied to distillation column 701b. The upstream end of a vapor pipe 733 is connected to, for example, the upper part of distillation column 701b, and the downstream end of the vapor pipe 733 is connected to a cooler 702b. The mixed liquid vapor from distillation column 701b is cooled and condensed by cooler 702b, changing into a mixed liquid. The upstream end of a first liquid feed pipe 78 is connected to cooler 702b, and the mixed liquid from cooler 702b is supplied to first dehydrator 60 through first liquid feed pipe 78.

[0084] The second dehydrator 70 may include a pump and a valve (not shown). For example, a liquid supply valve may be inserted in the first liquid supply pipe 78, and a pump may be inserted in the liquid pipe 732.

[0085] As described above, in the example of FIG. 4, the second dehydrator 70 separates water from the mixed liquid using the distillation column 701 and the cooler 702 to increase the solvent concentration of the mixed liquid. Also, in the example of FIG. 4, the second dehydrator 70 includes multiple distillation columns 701 and multiple coolers 702. This increases the solvent concentration of the mixed liquid each time the mixed liquid passes through a pair of the distillation column 701 and the cooler 702. Therefore, the second dehydrator 70 can increase the solvent concentration of the mixed liquid by a larger amount than when a single distillation column 701 and a single cooler 702 are used. The increase in the solvent concentration in the second dehydrator 70 is preset so that the solvent concentration after the increase is equal to or greater than the lower limit of the concentration of the first separation membrane 62c. The number of distillation columns 701 and the coolers 702 is preset according to the increase in the solvent concentration.

[0086] <3-1-2. 1st dehydrator> In the example of FIG. 4, the first dehydrator 60 includes a concentration tank Tk1 and a first circulation section 61.

[0087] (a) Concentration tank Tk1 The concentration tank Tk1 is connected to the downstream end of the first liquid supply pipe 78. The mixed liquid is supplied to the concentration tank Tk1 from the second dehydrator 70 through the first liquid supply pipe 78. The concentration tank Tk1 stores the mixed liquid. As described above, the solvent concentration of the mixed liquid is equal to or higher than the lower limit concentration of the first separation membrane 62c.

[0088] (b) First circulation section 61 The first circulation section 61 includes a first membrane separator 62 and a first circulation pipe 63. The first circulation pipe 63 is connected to the concentration tank Tk1. The first circulation pipe 63 is a pipe that returns the mixed liquid from the concentration tank Tk1 to the concentration tank Tk1. In other words, the first circulation pipe 63 forms a first circulation path that circulates the mixed liquid stored in the concentration tank Tk1 so that it flows out of the concentration tank Tk1 and returns to the concentration tank Tk1. In the example of FIG. 4, the upstream end of the first circulation pipe 63 is connected to the bottom of the concentration tank Tk1, and the downstream end of the first circulation pipe 63 is connected to the top of the concentration tank Tk1.

[0089] The first membrane separator 62 is provided in the first circulation piping 63. Specifically, the first mixing path 62a of the first membrane separator 62 is inserted into the first circulation piping 63 and constitutes part of the first circulation path of the first circulation unit 61. Therefore, the mixed liquid passes through the first mixing path 62a. A portion of the water in the mixed liquid that flows into the first mixing path 62a passes through the first separation membrane 62c and flows into the first water path 62b. Due to this dehydration, the solvent concentration of the mixed liquid immediately after the first membrane separator 62 becomes higher in the first circulation piping 63 than the solvent concentration of the mixed liquid immediately before the first membrane separator 62. Because the first circulation unit 61 circulates the mixed liquid through the first circulation piping 63, the mixed liquid continues to flow into the first membrane separator 62. Therefore, the first membrane separator 62 continues to separate water from the mixed liquid. As a result, the solvent concentration of the mixed liquid during circulation increases over time. Hereinafter, the liquid separated from the mixed liquid by the first membrane separator 62 will also be referred to as a separated liquid. The separated liquid is mostly water.

[0090] The first separation membrane 62c may be a zeolite membrane, an organic separation membrane, or a CNT (carbon nanotube) separation membrane. The zeolite membrane is, for example, a tetrahedral (SiO4) 4- and (AlO4) 5- The first separation membrane 62c has a crystalline structure in which carbon nanotubes are interconnected. The organic separation membrane is, for example, an organic membrane such as polyvinyl alcohol, chitosan, or polyimide. The CNT separation membrane is, for example, a membrane obtained by adding carbon nanotubes to a membrane such as polyamide. Alternatively, a two-dimensional material may be used as the material for the first separation membrane 62c. The two-dimensional material is a material composed of one atomic layer, and may be, for example, molybdenum sulfide (MoS2) or a composite atomic layer compound of an early transition metal (such as titanium or vanadium) and a light element (carbon or nitrogen). Alternatively, the first separation membrane 62c may be made of a metal organic framework (MOF) material or a carbon material (such as graphene or graphene oxide). In this example, a zeolite membrane is used as the first separation membrane 62c.

[0091] The upstream end of a separation discharge pipe 66 is connected to the first water path 62b. The separated liquid is discharged to the outside (for example, a wastewater treatment unit of a factory facility) through the separation discharge pipe 66. A pressure reducing pump for reducing the pressure in the first water path 62b may be provided in the separation discharge pipe 66. As shown in FIG. 4, a discharge valve 67 is inserted in the separation discharge pipe 66.

[0092] In the example of FIG. 4, the first circulation section 61 includes a first membrane separator 62, a first circulation pipe 63, a pump 64 which is an example of a liquid delivery section, a first switching valve 651, and a second switching valve 652.

[0093] The pump 64 is inserted in the first circulation pipe 63. As an example, the pump 64 is provided at a position upstream of the first membrane separator 62. The first switching valve 651 and the second switching valve 652 are inserted in the first circulation pipe 63. The first switching valve 651 is provided at a position downstream of the first membrane separator 62. The second switching valve 652 is provided at a position upstream of the pump 64.

[0094] Various sensors may be inserted in the first circulation pipe 63. For example, a concentration sensor Sn63 that measures the concentration of an organic solvent (here, for example, IPA) in the fluid flowing through the first circulation pipe 63, a flow rate sensor (flow meter) Sn64 that measures the flow rate of the fluid flowing through the first circulation pipe 63, and a pressure sensor Sn61 that measures the pressure of the fluid flowing through the first circulation pipe 63 are inserted in the first circulation pipe 63. The concentration sensor Sn63 is inserted, for example, at a position downstream of the first membrane separator 62. The flow rate sensor Sn64 is inserted, for example, at a position upstream of the pump 64. The pressure sensor Sn61 is inserted, for example, at a position downstream of the pump 64 and upstream of the first membrane separator 62.

[0095] <3-1-3.Recycled liquid supply section 89> 4, the first dehydrator 60 also includes a reused liquid supply unit 89. The reused liquid supply unit 89 supplies reused liquid to a supply tank Tk3. The reused liquid supply unit 89 includes a second liquid supply pipe 85, a liquid supply valve 86, and a pump 64, which is an example of a liquid supply unit.

[0096] In the example of FIG. 4 , the supply tank Tk3 is connected to the first circulation pipe 63 through the second liquid feed pipe 85. That is, the downstream end of the second liquid feed pipe 85 is connected to the supply tank Tk3, and the upstream end of the second liquid feed pipe 85 is connected to the first circulation pipe 63. Specifically, the upstream end of the second liquid feed pipe 85 is connected to the first circulation pipe 63 at a position between the pump 64 and the first switching valve 651. As an example, the upstream end of the second liquid feed pipe 85 is connected to the first circulation pipe 63 at a position between the pump 64 and the first membrane separator 62. A liquid feed valve 86 is interposed in the second liquid feed pipe 85. Note that the upstream end of the second liquid feed pipe 85 does not necessarily have to be connected to the first circulation pipe 63, and may be connected to the concentration tank Tk1. In this case, a pump other than the pump 64 is provided in the second liquid feed pipe 85.

[0097] <New liquid supply> 3, the supply tank Tk3 is connected to a new liquid supply source 403 through a new liquid pipe 401. That is, the downstream end of the new liquid pipe 401 is connected to the supply tank Tk3, and the upstream end of the new liquid pipe 401 is connected to the new liquid supply source 403. The new liquid supply source 403 is a supply source of an unused organic solvent (e.g., IPA with a concentration of 99.8 wt % or more) that has never been supplied to a substrate W. A new liquid valve 402 is inserted in the new liquid pipe 401.

[0098] The supply tank Tk3 is connected to the IPA nozzle 43c through the third liquid supply pipe 404. That is, the supply tank Tk3 is connected to one end of the third liquid supply pipe 404, and the IPA nozzle 43c (specifically, the IPA pipe 432c connected to the IPA nozzle 43c) is connected to the other end of the third liquid supply pipe 404. Here, for example, the third liquid supply pipe 404 is connected to the IPA nozzles 43c provided in each of the multiple processing units 4 belonging to the same tower.

[0099] A pump (supply side liquid feed pump) 405 is inserted in the third liquid feed pipe 404. A filter 407 is inserted in the third liquid feed pipe 404 at a position downstream of the supply side liquid feed pump 405. A temperature regulator 406 is inserted in the third liquid feed pipe 404 at a position upstream of the filter 407 and downstream of the supply side liquid feed pump 405.

[0100] Various sensors are inserted in the third liquid supply pipe 404. For example, a temperature sensor Sn41 that measures the temperature of the fluid flowing through the third liquid supply pipe 404 is inserted in the third liquid supply pipe 404. The temperature sensor Sn41 is inserted, for example, at a position upstream of the filter 407 and downstream of the temperature regulator 406. The temperature regulator 406 adjusts the temperature of the reuse liquid supplied to the processing unit 4 to within a predetermined temperature range according to the processing of the substrate W.

[0101] <3-2. Example of Operation of Organic Solvent Recovery Unit 5> FIG. 5 is a flowchart showing an example of the operation of the organic solvent recovery section 5. First, the second dehydrator 70 separates water from the mixed liquid from the processing unit 4 to increase the solvent concentration of the mixed liquid (step S1: second dehydrator process: corresponding to the first process). Specifically, the control unit 6 first opens the recovery valve 52 to supply the mixed liquid from the processing unit 4 to the second dehydrator 70 through the recovery pipe 51. Then, the control unit 6 controls the distillation column 701 and the cooler 702 to increase the solvent concentration of the mixed liquid in the second dehydrator 70 to a concentration lower limit (e.g., 50 wt%) of the first separation membrane 62c or higher. For example, the solvent concentration of the mixed liquid after separation by the second dehydrator 70 is closer (e.g., approximately 60%) to the concentration lower limit (e.g., 50 wt%) of the first separation membrane 62c than to the reuse standard value (e.g., 99 wt%). This mixed liquid is supplied to the first dehydrator 60 through the first liquid supply pipe 78. As an example, the mixed liquid is stored in a concentration tank Tk1.

[0102] Next, the first dehydrator 60 separates water from the mixed liquid to further increase the solvent concentration of the mixed liquid (step S2: first dehydrator process: corresponding to the second process). Specifically, the first circulation unit 61 circulates the mixed liquid through the first circulation piping 63. As an example, the control unit 6 opens the first switching valve 651, the second switching valve 652, and the discharge valve 67, and operates the pump 64. As a result, the mixed liquid circulates through the first circulation path including the concentration tank Tk1 and the first circulation piping 63. Due to this circulation, the mixed liquid continues to pass through the first membrane separator 62. Therefore, the first membrane separator 62 continues to separate the separated liquid from the mixed liquid, and the separated liquid continues to be discharged to the outside through the separation discharge piping 66. Therefore, the solvent concentration of the mixed liquid during circulation increases over time.

[0103] The control unit 6 circulates the mixed solution through the first circulation unit 61 until the solvent concentration of the circulating mixed solution reaches or exceeds a predetermined reuse standard value. The reuse standard value may be, for example, 60 wt% or more, 70 wt% or more, 80 wt% or more, 90 wt% or more, 95 wt% or more, or 99 wt% or more. For example, the control unit 6 may compare the solvent concentration measured by the concentration sensor Sn63 with the reuse standard value, and when the solvent concentration reaches or exceeds the reuse standard value, the control unit 6 may cause the first circulation unit 61 to stop circulation. Specifically, the control unit 6 closes the first switching valve 651, the second switching valve 652, and the discharge valve 67, and stops the pump 64.

[0104] This circulation causes the concentration tank Tk1 to store a mixed solution with an increased solvent concentration (i.e., a reused solution). The control unit 6 may cause the first circulation unit 61 to stop circulation when a predetermined first spin-drying time has elapsed. The first spin-drying time is set in advance to, for example, a time required for the solvent concentration to reach or exceed the reuse reference value. The first spin-drying time may be set, for example, to tens of minutes or more or several hours or more.

[0105] Next, the reuse liquid supply unit 89 supplies the reuse liquid to the supply tank Tk3 (step S3: supply step: third step). Specifically, the control unit 6 opens the liquid supply valve 86 and operates the pump 64. As a result, the reuse liquid in the concentration tank Tk1 is supplied to the supply tank Tk3 through at least the second liquid supply pipe 85.

[0106] As described above, the organic solvent recovery section 5 increases the solvent concentration of the mixed liquid from the processing unit 4 and supplies the mixed liquid to the supply tank Tk3 as a reused liquid.

[0107] In the above example, the second dehydrator 70 first increases the solvent concentration of the mixed liquid using the distillation column 701 and the cooler 702 (step S1). The lower limit of the concentration of the distillation column 701 is very low, for example, it can be almost zero. Therefore, even if the solvent concentration of the mixed liquid discharged from the treatment unit 4 is very low, the second dehydrator 70 can appropriately increase the solvent concentration of the mixed liquid. On the other hand, the power consumption of the distillation column 701 and the cooler 702 is relatively large, and the energy efficiency is low. The energy efficiency here may be, for example, the ratio of the increase in solvent concentration to the power consumption. Furthermore, the size of the distillation column 701 is larger than that of the first membrane separator 62. Furthermore, due to the principle of distillation, it is difficult for the second dehydrator 70 to increase the solvent concentration of the mixed liquid above the azeotropic point.

[0108] In the first embodiment, after the second dehydrator 70 increases the solvent concentration of the mixed liquid to or above the lower limit concentration of the first separation membrane 62c, the first dehydrator 60 further increases the solvent concentration of the mixed liquid using the first membrane separator 62 (step S2). Because the energy efficiency of membrane separation is higher than the energy efficiency of distillation, the organic solvent recovery unit 5 can increase the solvent concentration of the mixed liquid more efficiently. In other words, the organic solvent recovery unit 5 can increase the solvent concentration of the mixed liquid more efficiently than when only the second dehydrator 70 increases the solvent concentration of the mixed liquid. Furthermore, according to the principle of membrane separation using the first membrane separator 62, it is also possible to increase the solvent concentration of the mixed liquid to or above the azeotropic point. In other words, the organic solvent recovery unit 5 can more easily increase the solvent concentration of the mixed liquid to a value above the azeotropic point.

[0109] Furthermore, in the above-described example, the first dehydrator 60 repeatedly flows the mixed liquid into the first membrane separator 62 by circulating it through the first circulation unit 61, thereby increasing the solvent concentration of the mixed liquid. The increase in solvent concentration by the first membrane separator 62 increases as the size of the first membrane separator 62 (i.e., the size of the first separation membrane 62c) increases. Therefore, if the first dehydrator 60 does not circulate the mixed liquid, the size of the first membrane separator 62 must be increased to ensure the increase in solvent concentration. In contrast, in the above-described specific example, the first dehydrator 60 increases the solvent concentration of the mixed liquid by circulating it through the first circulation unit 61. Therefore, the size of the first membrane separator 62 (i.e., the size of the first separation membrane 62c) required to increase the solvent concentration of the mixed liquid to the reuse standard value can be reduced.

[0110] <Second embodiment> The configuration of the substrate processing apparatus 100 according to the second embodiment is similar to the configuration of the substrate processing apparatus 100 according to the first embodiment. However, in the second embodiment, a specific example of the second dehydrator 70 differs from that of the first embodiment. Fig. 6 is a diagram schematically showing an example of the second dehydrator 70 according to the second embodiment. In the example of Fig. 6, the second dehydrator 70 includes an ultrasonic atomization separator 704. The ultrasonic atomization separator 704 is connected to the downstream end of the recovery pipe 51, the upstream end of the first liquid supply pipe 78, and the upstream end of the separation and discharge pipe 705.

[0111] The mixed liquid flows into ultrasonic atomization separator 704 through recovery pipe 51. Ultrasonic atomization separator 704 converts the mixed liquid into mist using ultrasonic vibrations. This mixed liquid mist includes an organic solvent mist and a water mist. The mass distribution of these mist differs. For example, the organic solvent mist tends to be lighter than the water mist. Ultrasonic atomization separator 704 separates the water from the mixed liquid by moving the light organic solvent mist primarily upward and the heavier water mist primarily downward.

[0112] For example, the ultrasonic atomization separator 704 includes an atomization tank, an ultrasonic vibrator, a separation container, and a gas supply unit, all of which are not shown. The mixed liquid flows into the atomization tank from the recovery pipe 51. The ultrasonic vibrator atomizes the mixed liquid in the tank. Mist flows into the separation container from the atomization tank. The mist includes an organic solvent mist and a water mist. The gas supply unit supplies gas from the bottom of the separation container, causing the light organic solvent mist to move primarily upward and the heavy water mist to move primarily downward. The upstream end of the separation discharge pipe 705 is connected to the bottom of the separation container. Therefore, the water mist from the separation container mainly flows into the separation discharge pipe 705. The upstream end of the first liquid supply pipe 78 is connected to the top of the separation container. The organic solvent mist is supplied to the first dehydrator 60 through the first liquid supply pipe 78. A tank for joining the organic solvent mists may be provided between the separation container and the first liquid supply pipe 78.

[0113] The ultrasonic atomization separator 704 also has a very low lower limit of concentration, for example, approximately zero. Therefore, even if the mixed liquid discharged from the processing unit 4 has a very low solvent concentration, the second dehydrator 70 can appropriately increase the solvent concentration of the mixed liquid.

[0114] On the other hand, ultrasonic atomization separator 704 requires electricity to vibrate the ultrasonic vibrator and electricity to supply gas. Furthermore, if a gas other than air (such as nitrogen gas or a rare gas) is used, the cost of the gas will also be required, increasing running costs.

[0115] In the first embodiment, after the second dehydrator 70 increases the solvent concentration of the mixed liquid to or above the lower limit concentration value of the first separation membrane 62c, the first dehydrator 60 further increases the solvent concentration of the mixed liquid using the first membrane separator 62. Because the energy efficiency of membrane separation is higher than the energy efficiency of atomization separation, the organic solvent recovery unit 5 can increase the solvent concentration of the mixed liquid more efficiently. Therefore, the organic solvent recovery unit 5 can increase the solvent concentration of the mixed liquid more efficiently. In addition, running costs can be reduced.

[0116] <Third embodiment> FIG. 7 is a schematic diagram illustrating an example of an organic solvent recovery section 5 according to the third embodiment. In the example of FIG. 7, the second dehydrator 70 includes a second membrane separator 72. The mixed liquid discharged from the treatment unit 4 flows into the second membrane separator 72. The second membrane separator 72 separates water from the mixed liquid to increase the solvent concentration of the mixed liquid. The second membrane separator 72 includes a second mixing path 72a, a second water path 72b, and a second separation membrane 72c. The second mixing path 72a, the second water path 72b, and the second separation membrane 72c are similar to the first mixing path 62a, the first water path 62b, and the first separation membrane 62c, respectively.

[0117] A portion of the water in the mixed liquid that has flowed into the second mixing path 72a passes through the second separation membrane 72c and flows into the second water path 72b. The separated liquid that has flowed into the second water path 72b is discharged to the outside (for example, a wastewater treatment unit of a factory facility) through the separation discharge pipe 76.

[0118] The solvent concentration of the mixed liquid that has passed through the second mixing path 72a becomes higher than the solvent concentration of the mixed liquid immediately before it entered the second mixing path 72a. The second dehydrator 70 uses the second membrane separator 72 to increase the solvent concentration of the mixed liquid to or above the lower limit of the concentration of the first separation membrane 62c.

[0119] The concentration lower limit of the second separation membrane 72c is lower than the concentration lower limit of the first separation membrane 62c and is equal to or lower than the solvent concentration of the mixed liquid from the treatment unit 4. Here, we will explain the case where the first separation membrane 62c and the second separation membrane 72c are zeolite membranes. The concentration lower limit of the zeolite membrane is due to differences in the lattice structure of the zeolite membrane. Differences in the lattice structure of the zeolite membrane can be indicated by type (also called structure code). For example, zeolite membrane types include LTA type, CHA type, and DDR type. The concentration lower limit of the LTA type zeolite membrane is, for example, about 50 wt%, the concentration lower limit of the CHA type zeolite membrane is, for example, about 70 wt%, and the concentration lower limit of the DDR type zeolite membrane is, for example, about 90 wt%.

[0120] As one example, the second separation membrane 72c is an LTA-type zeolite membrane, and the first separation membrane 62c is a CHA-type or DDR-type zeolite membrane. As another example, the second separation membrane 72c is a CHA-type zeolite membrane, and the first separation membrane 62c is a DDR-type zeolite membrane. More generally, the first separation membrane 62c is a first-type zeolite membrane, and the second separation membrane 72c is a second-type zeolite membrane having a lower concentration limit than the first-type zeolite membrane.

[0121] Here, it is also possible that the solvent concentration of the mixed liquid from treatment unit 4 will be below the lower limit of the concentration of second separation membrane 72c. In this case, a third dehydrator (not shown) may be provided upstream of second dehydrator 70. The third dehydrator separates water from the mixed liquid from treatment unit 4 and increases the solvent concentration of the mixed liquid to or above the lower limit of the concentration of second separation membrane 72c. The mixed liquid after separation by the third dehydrator is supplied to second dehydrator 70. As an example, the third dehydrator may include a distillation column 701 and a cooler 702, or may include an ultrasonic atomization separator 704.

[0122] Furthermore, the separation constant of the first separation membrane 62c is higher than that of the second separation membrane 72c. The separation constant here is an index that indicates the solvent concentration of the mixed liquid after circulating the mixed liquid under predetermined conditions in a circulation path equipped with a membrane separator. The conditions here include, for example, the initial value of the solvent concentration of the mixed liquid, the flow rate and temperature during circulation of the mixed liquid, and the circulation time. The higher the solvent concentration of the mixed liquid after circulation, the larger the separation constant. Conversely, the higher the separation constant, the greater the increase in the solvent concentration of the organic solvent that the membrane separator can achieve.

[0123] As described above, in the third embodiment, the second dehydrator 70 includes the second membrane separator 72. Therefore, compared to methods such as distillation and atomization separation, the second dehydrator 70 can separate water from the mixed liquid with high efficiency and increase the solvent concentration of the mixed liquid.

[0124] Furthermore, the concentration lower limit of the second separation membrane 72c is lower than the concentration lower limit of the first separation membrane 62c. Therefore, even if the solvent concentration of the mixed liquid from the processing unit 4 is lower than the concentration lower limit of the first separation membrane 62c, as long as it is equal to or higher than the concentration lower limit of the second separation membrane 72c, the organic solvent recovery section 5 can increase the solvent concentration of the mixed liquid to or above the reuse standard value. Moreover, the separation constant of the first separation membrane 62c is larger than the separation constant of the second separation membrane 72c. Therefore, the organic solvent recovery section 5 can increase the solvent concentration of the mixed liquid to or above the reuse standard value more efficiently than when only the second dehydrator 70 increases the solvent concentration of the mixed liquid.

[0125] <More specific first example of organic solvent recovery section 5> FIG. 8 is a diagram schematically showing a first example of a more specific configuration of the organic solvent recovery section 5 according to the third embodiment.

[0126] 8, the second dehydrator 70 includes a concentration tank Tk1 and a second circulation unit 71. The concentration tank Tk1 is connected to the downstream end of the recovery pipe 51. The concentration tank Tk1 stores the mixed liquid that flows in from the processing unit 4 through the recovery pipe 51. Here, the solvent concentration of the mixed liquid from the processing unit 4 is assumed to be equal to or greater than the concentration lower limit value (e.g., 50 wt%) of the second separation membrane 72c and less than the concentration lower limit value (e.g., 70 wt%) of the first separation membrane 62c.

[0127] The second circulation section 71 includes a second membrane separator 72 and a second circulation pipe 73. The second circulation pipe 73 is connected to the concentration tank Tk1. The second circulation pipe 73 is a pipe that returns the mixed liquid from the concentration tank Tk1 to the concentration tank Tk1. In other words, the second circulation pipe 73 forms a second circulation path in which the mixed liquid stored in the concentration tank Tk1 flows out of the concentration tank Tk1 and circulates back to the concentration tank Tk1. In the example of FIG. 8, the upstream end of the second circulation pipe 73 is connected to the bottom of the concentration tank Tk1, and the downstream end of the second circulation pipe 73 is connected to the top of the concentration tank Tk1.

[0128] The second membrane separator 72 is provided in the second circulation pipe 73. Specifically, the second mixing path 72a of the second membrane separator 72 is inserted into the second circulation pipe 73 and constitutes part of the second circulation path of the second circulation section 71. Therefore, the mixed liquid passes through the second mixing path 72a. A portion of the water in the mixed liquid that flows into the second mixing path 72a passes through the second separation membrane 72c and flows into the second water path 72b. Due to this dehydration, the solvent concentration of the mixed liquid immediately after the second membrane separator 72 becomes higher in the second circulation pipe 73 than the solvent concentration of the mixed liquid immediately before the second membrane separator 72. Because the second circulation section 71 circulates the mixed liquid through the second circulation pipe 73, the mixed liquid continues to flow into the second membrane separator 72. Therefore, the second membrane separator 72 continues to separate water from the mixed liquid. As a result, the solvent concentration of the mixed liquid during circulation increases over time.

[0129] The upstream end of a separation discharge pipe 76 is connected to the second water path 72b. The separated liquid is discharged to the outside (for example, a wastewater treatment unit of a factory facility) through the separation discharge pipe 76. A pressure reducing pump for reducing the pressure in the second water path 72b may be provided in the separation discharge pipe 76. As shown in FIG. 8, a discharge valve 77 is inserted in the separation discharge pipe 76.

[0130] 8, second circulation section 71 includes, in addition to second membrane separator 72 and second circulation piping 73, a pump 74, which is an example of a liquid delivery section, a first switching valve 751, and a second switching valve 752. Pump 74, first switching valve 751, and second switching valve 752 are similar to pump 64, first switching valve 651, and second switching valve 652 in the first embodiment, respectively.

[0131] Various sensors may be inserted in the second circulation pipe 73. For example, a concentration sensor Sn73, a flow rate sensor Sn74, and a pressure sensor Sn71 are inserted in the second circulation pipe 73. The concentration sensor Sn73, the flow rate sensor Sn74, and the pressure sensor Sn71 are similar to the concentration sensor Sn63, the flow rate sensor Sn64, and the pressure sensor Sn61 in the first embodiment, respectively.

[0132] In the example of FIG. 8, the upstream end of the first liquid feed pipe 78 is connected to the second circulation pipe 73 at a position between the pump 74 and the first switching valve 751. As an example, the upstream end of the first liquid feed pipe 78 is connected to the second circulation pipe 73 at a position between the pump 74 and the second membrane separator 72. Note that the upstream end of the first liquid feed pipe 78 does not necessarily have to be connected to the second circulation pipe 73, and may be connected to the concentration tank Tk1. In this case, a pump separate from the pump 74 is provided in the first liquid feed pipe 78. In the example of FIG. 8, a liquid feed valve 79 is inserted in the first liquid feed pipe 78.

[0133] As described above, the second dehydrator 70 includes the second circulation unit 71. The second circulation unit 71 circulates the mixed liquid through the second circulation path including the concentration tank Tk1 and the second circulation piping 73. Specifically, the control unit 6 opens the first switching valve 751, the second switching valve 752, and the discharge valve 77, and operates the pump 74. This causes the mixed liquid to continue flowing into the second membrane separator 72. In other words, the mixed liquid that has passed through the second membrane separator 72 repeatedly flows into the second membrane separator 72 through the second circulation path. This causes the solvent concentration of the mixed liquid in the concentration tank Tk1 to increase over time.

[0134] The control unit 6 circulates the mixed solution through the second circulation unit 71 until the solvent concentration of the circulating mixed solution reaches at least the lower limit of the concentration of the first separation membrane 62c. For example, the control unit 6 may compare the solvent concentration measured by the concentration sensor Sn73 with a concentration reference value and cause the second circulation unit 71 to stop circulation when the solvent concentration reaches or exceeds the concentration reference value. Specifically, the control unit 6 closes the first switching valve 751, the second switching valve 752, and the discharge valve 77 and stops the pump 74. This causes the mixed solution having a solvent concentration equal to or greater than the concentration reference value to be stored in the concentration tank Tk1. The concentration reference value may be set in advance to a value equal to or greater than the lower limit of the concentration of the first separation membrane 62c (e.g., 70 wt%). The concentration reference value may be set, for example, to a value closer to the lower limit of the concentration of the first separation membrane 62c (e.g., 70 wt%) than the reuse reference value (e.g., 99 wt%).

[0135] The control unit 6 may stop circulation in the second circulation unit 71 when a predetermined second spin-drying time has elapsed. The second spin-drying time is set in advance to, for example, a time required for the solvent concentration to reach or exceed the reference concentration value. The second spin-drying time may be set, for example, to several tens of minutes or more or several hours or more.

[0136] As described above, according to the organic solvent recovery unit 5 of the first example, the solvent concentration of the mixed liquid is increased by circulation through the second circulation unit 71. In other words, the mixed liquid repeatedly flows into the second membrane separator 72. Therefore, it is possible to reduce the size of the second membrane separator 72 (i.e., the size of the second separation membrane 72c) required to increase the solvent concentration of the mixed liquid to the concentration reference value.

[0137] <1st dehydrator> 8, the downstream end of the first liquid feed pipe 78 is connected to the first membrane separator 62 of the first dehydrator 60. Specifically, the downstream end of the first liquid feed pipe 78 is connected to the upstream portion of the first mixing path 62a of the first membrane separator 62. The upstream end of the second liquid feed pipe 85 is connected to the downstream portion of the first mixing path 62a of the first membrane separator 62. The upstream end of the separation and discharge pipe 66 is connected to the first water path 62b of the first membrane separator 62.

[0138] In this first dehydrator 60, the control unit 6 opens the second switching valve 752, the liquid feed valve 79, the discharge valve 67, and the liquid feed valve 86, and operates the pump 74. As a result, the mixed liquid from the second dehydrator 70 flows into the first membrane separator 62 through the first liquid feed piping 78. The first membrane separator 62 separates water from the mixed liquid and discharges the separated liquid to the outside through the separation discharge piping 66, while supplying the separated mixed liquid (i.e., the recycled liquid) to the supply tank Tk3 through the second liquid feed piping 85.

[0139] In the first example, the first dehydrator 60 does not circulate the mixed liquid, so that the time required for the operation of the first dehydrator 60 can be shortened.

[0140] An example of the operation of the organic solvent recovery unit 5 according to the first example is the same as that shown in Fig. 5. That is, the second dehydrator 70 increases the solvent concentration of the mixed liquid to or above the lower limit concentration value of the first separation membrane 62c (step S1), as described above, the first dehydrator 60 increases the solvent concentration of the mixed liquid from the second dehydrator 70 to or above the reuse standard value (step S2), as described above, and the reuse liquid supply unit 89 supplies the mixed liquid (reuse liquid) to the supply tank Tk3 (step S3).

[0141] <Second more specific example of organic solvent recovery section> 9 is a diagram schematically illustrating a second example of a more specific configuration of the organic solvent recovery section 5 according to the third embodiment. The organic solvent recovery section 5 according to the second example differs from the organic solvent recovery section 5 according to the first example in the configuration of the first dehydrator 60. The first dehydrator 60 according to the second example has substantially the same configuration as the first dehydrator 60 in FIG. 4. However, in the example of FIG. 9, part of the first circulation piping 63 and part of the second circulation piping 73 are shared.

[0142] 9, the first circulation pipe 63 includes a downstream common pipe 671, a first individual pipe 630, and an upstream common pipe 672, which is an example of a common circulation pipe, and the second circulation pipe 73 includes a downstream common pipe 671, a second individual pipe 730, and an upstream common pipe 672. In other words, the downstream common pipe 671 and the upstream common pipe 672 are shared by the first circulation pipe 63 and the second circulation pipe 73. The upstream end of the upstream common pipe 672 is connected to, for example, the bottom of the concentration tank Tk1, and the downstream end of the downstream common pipe 671 is connected to, for example, the top of the concentration tank Tk1. The upstream ends of the first individual pipe 630 and the second individual pipe 730 are connected to the downstream end of the upstream common pipe 672, and the downstream ends of the first individual pipe 630 and the second individual pipe 730 are connected to the upstream end of the downstream common pipe 671.

[0143] The first individual pipe 630 is provided with a first membrane separator 62, and the second individual pipe 730 is provided with a second membrane separator 72. The pump 74 and the second switching valve 752 are inserted into the upstream common pipe 672. Therefore, the pump 74 and the second switching valve 752 are shared by both the first circulation section 61 and the second circulation section 71.

[0144] The organic solvent recovery section 5 is provided with a switching valve unit 790. In the example of FIG. 9 , the switching valve unit 790 includes a first three-way valve 791 and a second three-way valve 792. The switching valve unit 790 switches the circulation path between the first circulation path and the second circulation path. Specifically, the switching valve unit 790 switches between a first circulation state and a second circulation state, which will be described below. The first circulation state is a state in which the downstream common pipe 671 and the upstream common pipe 672 communicate with each other through the first individual pipe 630. The second circulation state is a state in which the downstream common pipe 671 and the upstream common pipe 672 communicate with each other through the second individual pipe 730. In the first circulation state, the mixed liquid circulates through the first circulation path, which includes the concentration tank Tk1 and the first circulation path 63. In the second circulation state, the mixed liquid circulates through the second circulation path, which includes the concentration tank Tk1 and the second circulation path 73.

[0145] 9 , the first three-way valve 791 is connected to the upstream end of the downstream common pipe 671, the downstream end of the first individual pipe 630, and the downstream end of the second individual pipe 730. The first three-way valve 791 switches between a first downstream circulation state in which the downstream common pipe 671 is connected to the first individual pipe 630, and a second downstream circulation state in which the downstream common pipe 671 is connected to the second individual pipe 730. The second three-way valve 792 is connected to the downstream end of the upstream common pipe 672, the upstream end of the first individual pipe 630, and the upstream end of the second individual pipe 730. The second three-way valve 792 switches between a first upstream circulation state in which the upstream common pipe 672 is connected to the first individual pipe 630, and a second upstream circulation state in which the upstream common pipe 672 is connected to the second individual pipe 730.

[0146] When the control unit 6 causes the first three-way valve 791 to select the first downstream circulation state and the second three-way valve 792 to select the first upstream circulation state, the mixed liquid circulates through the first circulation path. That is, the switching valve unit 790 selects the first circulation state. When the control unit 6 causes the first three-way valve 791 to select the second downstream circulation state and the second three-way valve 792 to select the second upstream circulation state, the mixed liquid circulates through the second circulation path. That is, the switching valve unit 790 selects the second circulation state.

[0147] In the second example, the second dehydrator 70 also operates first. That is, the control unit 6 controls the switching valve unit 790 to select the second circulation state when the solvent concentration of the mixed solution in the concentration tank Tk1 is a second value less than the concentration lower limit value of the first separation membrane 62c. The solvent concentration of the mixed solution in the concentration tank Tk1 may be measured, for example, by a concentration sensor (not shown). By selecting the second circulation state, the second dehydrator 70 initially operates. That is, the second dehydrator 70 circulates the mixed solution to the second circulation unit 71 through the second circulation path. The second dehydrator 70 circulates the mixed solution to the second circulation unit 71 until the solvent concentration of the mixed solution in the concentration tank Tk1 becomes equal to or greater than the concentration lower limit value of the first separation membrane 62c. Then, the control unit 6 controls the switching valve unit 790 to select the first circulation state when the solvent concentration of the mixed solution is a first value greater than or equal to the concentration lower limit value. This causes the first dehydrator 60 to operate. That is, the first dehydrator 60 circulates the mixed liquid through the first circulation path to the first circulation unit 61. The first dehydrator 60 circulates the mixed liquid through the first circulation unit 61 until the solvent concentration of the mixed liquid in the concentration tank Tk1 reaches or exceeds the reuse standard value. As a result, the reuse liquid is stored in the concentration tank Tk1.

[0148] 9, the upstream end of the second liquid supply pipe 85 is connected to the first circulation pipe 63 (specifically, the first individual pipe 630). For example, the control unit 6 opens the second switching valve 752 and the liquid supply valve 86, causes the first three-way valve 791 to select the second downstream circulation state, causes the second three-way valve 792 to select the first upstream circulation state, and operates the pump 74. As a result, the mixed liquid (recycled liquid) in the concentration tank Tk1 is supplied to the supply tank Tk3. Note that the upstream end of the second liquid supply pipe 85 may be connected to the second circulation pipe 73 or the concentration tank Tk1.

[0149] An example of the operation of the organic solvent recovery section 5 according to the second example is similar to that shown in FIG. 5 . However, the specific example of the operation is different. Here, the solvent concentration of the mixed solution from the processing unit 4 is lower than the lower limit of the concentration of the first separation membrane 62c. Therefore, first, the second dehydrator 70 increases the solvent concentration of the mixed solution to or above the lower limit of the concentration of the first separation membrane 62c by circulating it through the second circulation section 71 (step S1). Specifically, the control section 6 opens the second switching valve 752 and the discharge valve 77, causes the switching valve section 790 to select the second circulation state, and operates the pump 74. As a result, the mixed solution circulates through the second circulation path including the concentration tank Tk1 and the second circulation piping 73. As a result of this circulation, the mixed solution passes through the second membrane separator 72, and the solvent concentration of the mixed solution in the concentration tank Tk1 increases over time.

[0150] When the solvent concentration of the mixed liquid in the concentration tank Tk1 reaches or exceeds the concentration reference value, the second dehydrator 70 stops the circulation, and the first dehydrator 60 increases the solvent concentration of the mixed liquid to or above the reuse reference value through circulation by the first circulation unit 61 (step S2). Specifically, the control unit 6 opens the discharge valve 67 and causes the switching valve unit 790 to select the first circulation state. This causes the mixed liquid to circulate through the first circulation path including the concentration tank Tk1 and the first circulation piping 63. This circulation causes the mixed liquid to pass through the first membrane separator 62, so the solvent concentration of the mixed liquid in the concentration tank Tk1 increases over time. Note that the control unit 6 may close the discharge valve 77.

[0151] When the solvent concentration of the mixed solution in the concentration tank Tk1 reaches or exceeds the reuse standard value, the first circulation unit 61 stops circulation. Specifically, the control unit 6 closes the second switching valve 752 and the discharge valve 67, and stops the pump 74.

[0152] Next, the reused liquid supply unit 89 supplies the mixed liquid (that is, reused liquid) in the concentration tank Tk1, whose solvent concentration has been increased by the first dehydrator 60, to the supply tank Tk3 (step S3).

[0153] As described above, according to the second example, the first dehydrator 60 increases the solvent concentration of the mixed liquid by circulation through the first circulation section 61. This makes it possible to reduce the size of the first membrane separator 62 (i.e., the size of the first separation membrane 62c) required to increase the solvent concentration of the mixed liquid to or above the reuse standard value.

[0154] 9, the pump 74 is used for both the first circulation section 61 and the second circulation section 71. This makes it possible to reduce the manufacturing cost of the organic solvent recovery section 5.

[0155] <Fourth embodiment> 10 is a diagram schematically illustrating a first example of a substrate processing apparatus 100 according to the fourth embodiment. The substrate processing apparatus 100 according to the fourth embodiment differs from the substrate processing apparatus 100 according to the first embodiment in the presence or absence of a recovery destination switching unit 50. It can be said that the recovery destination switching unit 50 belongs to the organic solvent recovery unit 5. The recovery destination switching unit 50 switches between a first spinning state and a second spinning state, which will be described next. The first spinning state is a state in which the mixed liquid from the processing unit 4 is supplied to the first dehydrator 60, bypassing the second dehydrator 70. The second spinning state is a state in which the mixed liquid from the processing unit 4 is supplied to the second dehydrator 70.

[0156] The recovery destination switching unit 50 includes a recovery pipe 51 and a switching valve unit 520. In the example of FIG. 10, the recovery pipe 51 includes a first spin-drying pipe 511, a second spin-drying pipe 512, and a common recovery pipe 510. In the example of FIG. 10, a plurality of common recovery pipes 510 are provided corresponding to a plurality of processing units 4. In the example of FIG. 10, a plurality of common recovery pipes 510 are provided in a one-to-one relationship for a plurality of processing units 4. The upstream end of each common recovery pipe 510 is connected to the corresponding processing unit 4 (specifically, cup 42). The common recovery pipe 510 corresponds to the cup-side recovery pipe 424 described above.

[0157] The downstream end of first dehydration piping 511 is connected to first dehydrator 60. Furthermore, first dehydration piping 511 is connected to the downstream end of each common recovery piping 510. In the example of FIG. 10 , first dehydration piping 511 includes a first common piping 513 and a plurality of first branch pipings 514. The plurality of first branch pipings 514 are provided in a one-to-one correspondence with the plurality of common recovery pipings 510. The upstream end of each first branch piping 514 is connected to the downstream end of the corresponding common recovery piping 510, and the downstream end of each first branch piping 514 is connected to the first common piping 513. The downstream end of first common piping 513 corresponds to the downstream end of first dehydration piping 511.

[0158] The downstream end of second dehydration piping 512 is connected to second dehydrator 70. In addition, second dehydration piping 512 is connected to the downstream end of each common recovery piping 510. In the example of FIG. 10 , second dehydration piping 512 includes a second common piping 515 and a plurality of second branch pipings 516. The plurality of second branch pipings 516 are provided in a one-to-one correspondence with the plurality of common recovery pipings 510. The upstream end of each second branch piping 516 is connected to the downstream end of the corresponding common recovery piping 510, and the downstream end of the second branch piping 516 is connected to the second common piping 515. The downstream end of the second common piping 515 corresponds to the downstream end of the second dehydration piping 512.

[0159] 10, the switching valve section 520 includes a switching valve 521 and a switching valve 522. The switching valve section 520 switches between a state in which the common recovery pipe 510 is connected to the first dehydrator 60 (i.e., a first spinning state) and a state in which the common recovery pipe 510 is connected to the second dehydrator 70 (i.e., a second spinning state). In the example of FIG. 10, a plurality of switching valve sections 520 are provided in a one-to-one relationship with a plurality of processing units 4. That is, in the example of FIG. 10, a plurality of switching valves 521 are provided in a one-to-one relationship with a plurality of processing units 4, and a plurality of switching valves 522 are provided in a one-to-one relationship with a plurality of processing units 4. Each switching valve 521 is inserted in a corresponding first branch pipe 514, and each switching valve 522 is inserted in a corresponding second branch pipe 516.

[0160] The operation of the switching valve section 520 corresponding to one processing unit 4 will be described below. When the control section 6 closes the switching valve 521 and opens the switching valve 522, the mixed liquid from the processing unit 4 flows through the common recovery pipe 510 and the second spin-drying pipe 512 in this order and is supplied to the second dehydrator 70. In other words, the switching valve section 520 selects the second spin-drying state. When the control section 6 opens the switching valve 521 and closes the switching valve 522, the mixed liquid from the processing unit 4 flows through the common recovery pipe 510 and the first spin-drying pipe 511 in this order and is supplied to the first dehydrator 60. In other words, the switching valve section 520 selects the first spin-drying state.

[0161] The control unit 6 controls the recovery destination switching unit 50 based on the solvent concentration of the mixed liquid discharged from the processing unit 4. Specifically, the control unit 6 causes the recovery destination switching unit 50 to select the first dehydration state when the solvent concentration of the mixed liquid is a first value that is equal to or greater than the lower limit of the concentration of the first separation membrane 62c, and causes the recovery destination switching unit 50 to select the second dehydration state when the solvent concentration of the mixed liquid is a second value that is less than the lower limit of the concentration of the first separation membrane 62c. Here, the lower limit of the concentration of the second dehydrator 70 is assumed to be approximately zero.

[0162] 11 is a flowchart showing an example of the operation of the organic solvent recovery section 5 according to the fourth embodiment. First, the control section 6 acquires the solvent concentration of the mixed liquid discharged from the processing unit 4 (step S11: concentration acquisition step). Here, the solvent concentration of the mixed liquid discharged from the processing unit 4 is the solvent concentration of the mixed liquid before the operations of the first dehydrator 60 and the second dehydrator 70. A specific example of a method for acquiring the solvent concentration will be described in detail later.

[0163] Next, the control unit 6 determines whether the solvent concentration is equal to or greater than a predetermined switching reference value (step S12: concentration determination step). The switching reference value is set, for example, in advance to a value equal to or greater than the concentration lower limit value of the first separation membrane 62c. The switching reference value may be, for example, a value closer to the concentration lower limit value of the first separation membrane 62c than the reuse reference value. The switching reference value may be equal to the concentration reference value or may be less than the concentration reference value.

[0164] When the solvent concentration of the mixed liquid is less than the switching reference value, the second dehydrator 70 separates water from the mixed liquid to increase the solvent concentration of the mixed liquid (step S13: second dehydrator step). Specifically, the control unit 6 causes the recovery destination switching unit 50 to select the second dehydration state. As an example, the control unit 6 closes the switching valve 521 and opens the switching valve 522. As a result, the mixed liquid from the processing unit 4 is supplied to the second dehydrator 70. In other words, if the solvent concentration of the mixed liquid is less than the switching reference value, the first membrane separator 62 may not be usable, so the organic solvent recovery unit 5 supplies the mixed liquid to the second dehydrator 70, and the second dehydrator 70 reliably increases the solvent concentration of the mixed liquid to or above the lower limit concentration of the first separation membrane 62c.

[0165] When the second dehydrator 70 increases the solvent concentration of the mixed liquid to or above the concentration reference value, the first dehydrator 60 separates water from the mixed liquid to further increase the solvent concentration of the mixed liquid (step S14: first dehydrator process). The first dehydrator 60 increases the solvent concentration of the mixed liquid to or above the reuse reference value. In other words, the first dehydrator 60 produces reused liquid. Next, the reused liquid supply unit 89 supplies the reused liquid to the supply tank Tk3 (step S15: supply process).

[0166] On the other hand, in step S12, when the solvent concentration of the mixed liquid is equal to or higher than the switching reference value, the first dehydrator 60 separates water from the mixed liquid discharged from the treatment unit 4 to increase the solvent concentration of the mixed liquid (step S14: first dehydrator step). Specifically, the control unit 6 causes the recovery destination switching unit 50 to select the first dehydration state. As an example, the control unit 6 opens the switching valve 521 and closes the switching valve 522. In other words, when the solvent concentration of the mixed liquid is equal to or higher than the switching reference value, the highly efficient first membrane separator 62 can be used, and therefore the organic solvent recovery unit 5 supplies the mixed liquid from the treatment unit 4 to the first dehydrator 60, bypassing the second dehydrator 70.

[0167] The first dehydrator 60 increases the solvent concentration of the mixed liquid to the reuse standard value or higher (step S14), and the reuse liquid supply unit 89 supplies the reuse liquid to the supply tank Tk3 (step S15).

[0168] As described above, when the solvent concentration of the mixed liquid from the processing unit 4 is high, the second dehydrator 70 does not operate, and the first dehydrator 60 increases the solvent concentration of the mixed liquid. This makes it possible to avoid power consumption by the second dehydrator 70. On the other hand, when the solvent concentration of the mixed liquid from the processing unit 4 is low, the second dehydrator 70 first increases the solvent concentration of the mixed liquid to or above the lower limit concentration of the first separation membrane 62c. This makes it possible for the second dehydrator 70 to supply the first dehydrator 60 with a mixed liquid having a solvent concentration that is equal to or above the lower limit concentration of the first separation membrane 62c.

[0169] In addition, when the second dehydrator 70 includes the second membrane separator 72, a third dehydrator may be provided upstream of the second dehydrator 70. The lower limit of the concentration of the third dehydrator may be lower than the lower limit of the concentration of the second separation membrane 72c, for example, approximately zero. The destination switching unit 50 may switch the destination of the mixed liquid from the processing unit 4 among the first dehydrator 60, the second dehydrator 70, and the third dehydrator. For example, when the solvent concentration of the mixed liquid from the processing unit 4 is lower than a second switching reference value, the destination switching unit 50 supplies the mixed liquid to the third dehydrator. The second switching reference value is set to be equal to or higher than the lower limit of the concentration of the second separation membrane 72c and lower than the lower limit of the concentration of the first separation membrane 62c. The third dehydrator separates water from the mixed liquid and increases the solvent concentration of the mixed liquid to or higher than the lower limit of the concentration of the second dehydrator 70. The third dehydrator then supplies the separated mixed liquid to the second dehydrator 70. Furthermore, when the solvent concentration of the mixed liquid from the processing unit 4 is equal to or greater than the second switching reference value and less than the first switching reference value, the recovery destination switching unit 50 supplies the mixed liquid to the second dehydrator 70. The first switching reference value is set to be equal to or greater than the concentration lower limit value of the first separation membrane 62c and less than the reuse reference value. Furthermore, when the solvent concentration of the mixed liquid from the processing unit 4 is equal to or greater than the first switching reference value, the recovery destination switching unit 50 supplies the mixed liquid to the first dehydrator 60.

[0170] <How to obtain solvent concentration> <Calculation of solvent concentration based on recipe information> Next, an example of a method for acquiring the solvent concentration of the mixed liquid discharged from the processing unit 4 will be described. The solvent concentration of the mixed liquid discharged from the processing unit 4 depends on the processing content of the substrate W by the processing unit 4. For example, the processing unit 4 supplies pure water to the substrate W, and then supplies an organic solvent to the substrate W. In this processing, if the processing unit 4 supplies pure water to the substrate W at a high flow rate for a long period of time, the solvent concentration of the mixed liquid discharged from the processing unit 4 will be relatively low. On the other hand, if the processing unit 4 supplies an organic solvent to the substrate W at a high flow rate for a long period of time, the solvent concentration of the mixed liquid discharged from the processing unit 4 will be relatively high. In this way, the solvent concentration of the mixed liquid discharged from the processing unit 4 depends on the processing content.

[0171] 12 is a diagram schematically illustrating an example of a processing unit 4 according to the fourth embodiment. As shown in FIG. 12, the control unit 6 is connected to a storage unit 603. The storage unit 603 is, for example, a non-volatile storage unit, and specific examples thereof include a memory or a hard disk. The storage unit 603 stores recipe information D1 that defines the processing details for the substrate W. The recipe information D1 includes various information, such as the nozzle to be used, the flow rate of the processing liquid, the discharge time of the processing liquid, and the rotation speed of the substrate W for each processing.

[0172] 12, the processing unit 4 may include a plurality of cups 42. In the example of FIG. 12, the plurality of cups 42 are shown as cups 42A, 42B, and 42C. The cups 42A, 42B, and 42C are arranged concentrically. In the example of FIG. 12, the cup 42A is located on the outermost side, the cup 42C is located on the innermost side, and the cup 42B is located between the cups 42A and 42C.

[0173] The cup lifting mechanism 425 raises and lowers each cup 42. For example, the cup lifting mechanism 425 raises cup 42A to the upper position and lowers cups 42B and 42C to the lower position. In this state, the processing liquid splashed from the peripheral edge of the substrate W is received by cup 42A. Furthermore, the cup lifting mechanism 425 raises cups 42A and 42B to the upper position and lowers cup 42C to the lower position. In this state, the processing liquid splashed from the peripheral edge of the substrate W is received by cup 42B. Furthermore, the cup lifting mechanism 425 raises cups 42A, 42B, and 42C to the upper position. In this state, the processing liquid splashed from the peripheral edge of the substrate W is received by cup 42C.

[0174] 12, the processing liquid received in cup 42C flows into recovery piping 51. The processing liquid received in cup 42A flows into another recovery piping (not shown), and the processing liquid received in cup 42B flows into another recovery piping (not shown).

[0175] The processing unit 4 can change the cup 42 that receives the processing liquid depending on the type of processing liquid. For example, when supplying deionized water to the substrate W, the cup lifting mechanism 425 positions only the cup 42A in the upper position. In this case, the deionized water is received by the cup 42A. When supplying an organic solvent to the substrate W, the cup lifting mechanism 425 positions the cups 42A to 42C in the upper position. In this case, the organic solvent is received by the cup 42C and flows into the recovery pipe 51. That is, in this example, the cup 42C is a cup for the organic solvent, and the recovery pipe 51 is a recovery pipe for the organic solvent. In this way, the processing unit 4 can switch the cup used between the cup 42A and the cup 42C depending on the type of processing liquid. Information indicating the position of the cup 42 during each process is also included in the recipe information D1.

[0176] 12, the control unit 6 includes a concentration estimation unit 601. The concentration estimation unit 601 reads out recipe information D1 from a memory unit 603. The concentration estimation unit 601 calculates the solvent concentration of the mixed liquid discharged from the processing unit 4 (i.e., the mixed liquid flowing into the recovery pipe 51) based on the recipe information D1. Table 1 is a table that schematically shows a first example of the recipe information D1.

[0177] [Table 1]

[0178] Table 1 shows some of the processes for the substrate W. In Table 1, the recipe information D1 includes the number of each process, the rotation speed of the substrate W in each process, the time required for each process, the flow rate of the processing liquid in each process, the type of processing liquid in each process, and the cup used in each process. The cup used can be said to be information indicating the position of the cup 42.

[0179] Fig. 13 is a diagram schematically illustrating an example of the state of the processing unit 4 in each step in Table 1. Fig. 13(a) to Fig. 13(f) illustrate an example of the state of the processing unit 4 in the 30th step to the 35th step in Table 1, respectively.

[0180] In the 30th step in Table 1, the spin chuck 41 rotates the substrate W at 100 rpm for two seconds, while the rinse liquid nozzle 43b discharges pure water toward the substrate W at 2000 mL (milliliters) / min. Also, in the 30th step, the cup 42A is used. That is, as shown in FIG. 13(a), in the 30th step, pure water splashed from the periphery of the substrate W is received by the cup 42A.

[0181] In step 31, the spin chuck 41 rotates the substrate W at 10 rpm for one second. No processing liquid is supplied to the substrate W in step 31. In step 31, the rotation speed of the substrate W is low, so that the deionized water is maintained on the main surface of the substrate W, as shown in FIG. 13(b). This type of processing is also called a puddle process. Although not shown in Table 1, in practice, between steps 30 and 31, a step may be performed in which the rotation speed of the spin chuck 41 is gradually reduced to 10 rpm while the rinse liquid nozzle 43b discharges deionized water at 2000 mL / min. In puddle processing, the liquid film of deionized water on the main surface of the substrate W becomes thicker as the rotation speed of the substrate W decreases after the discharge of deionized water is stopped.

[0182] In the 32nd step, the spin chuck 41 rotates the substrate W at 10 rpm for one second, while the cup lifting mechanism 425 switches the cup in use from the cup 42A to the cup 42C (see FIG. 13(c)).

[0183] In the 33rd step, the spin chuck 41 rotates the substrate W at 10 rpm for four seconds, while the IPA nozzle 43c ejects the organic solvent at 100 mL / min toward the main surface of the substrate W. The organic solvent is, for example, IPA. As shown in FIG. 13(d), in the 33rd step, the processing liquid (pure water and organic solvent) may flow down from the periphery of the substrate W. In this case, the processing liquid is received in the cup 42C and flows into the upstream end of the recovery pipe 51.

[0184] In step 34, the spin chuck 41 rotates the substrate W at 1000 rpm for three seconds, while the IPA nozzle 43c discharges the organic solvent at 100 mL / min toward the main surface of the substrate W. As shown in FIG. 13(e), the organic solvent that has landed on the main surface of the substrate W flows radially outward and splashes outward from the periphery of the substrate W together with the pure water. The mixture of the organic solvent and pure water is received in the cup 42C and then flows into the upstream end of the recovery pipe 51. Through steps 33 and 34, the pure water on the main surface of the substrate W is replaced with the organic solvent.

[0185] In the 35th step, the spin chuck 41 rotates the substrate W at 1000 rpm for 2 seconds. In the 35th step, no processing liquid is supplied to the substrate W. As shown in FIG. 13(f), in the 35th step, some of the organic solvent on the main surface of the substrate W is scattered from the periphery of the substrate W. Also, some of the remaining organic solvent is evaporated. As a result, the main surface of the substrate W is dried.

[0186] As described above, the cup 42C is raised to the upper position in the 31st step (see also FIG. 13(c)). Therefore, the cup 42C can receive the processing liquid (pure water and organic solvent, i.e., the mixed liquid) from the 31st step to the 35th step. The processing liquid flows into the upstream end of the recovery pipe 51. Hereinafter, the period from the 31st step to the 35th step will also be referred to as the discharge period. The discharge period is the period during which the cup 42C can receive the processing liquid.

[0187] The solvent concentration (average value) of the mixed liquid flowing into the recovery pipe 51 during the discharge period can be calculated based on the pure water discharge amount and solvent discharge amount, which will be described below. The pure water discharge amount is the total amount of pure water flowing into the recovery pipe 51 during the discharge period, i.e., the total amount of pure water received in the cup 42C during the discharge period. The solvent discharge amount is the total amount of organic solvent flowing into the recovery pipe 51 during the discharge period, i.e., the total amount of organic solvent received in the cup 42C during the discharge period.

[0188] First, the amount of pure water discharged will be explained. In the example of Table 1, pure water is not supplied during the discharge period (steps 31 to 35). Therefore, the amount of pure water discharged is the amount of pure water present on the main surface of the substrate W at the start of step 31 (see also FIG. 13(c)). Hereinafter, this amount of pure water will be referred to as the pure water film amount. Since the thickness of the liquid film of pure water present on the main surface of the substrate W depends on the rotation speed of the substrate W at the start of step 31, the pure water film amount depends on this rotation speed. The start of step 31 can also be said to be the start time of switching from cup 42A to cup 42C.

[0189] FIG. 14 is a graph showing an example of the distance from the center of the substrate W to each position on the substrate W and the thickness of the pure water liquid film at each position. In other words, each graph shows the contour of the pure water liquid surface. FIG. 14 shows multiple graphs G1 to G4 that represent different rotation speeds of the substrate W. The rotation speed corresponding to graph G1 is the lowest, at 10 rpm. The rotation speed corresponding to graph G2 is the next highest, at 50 rpm. The rotation speed corresponding to graph G3 is the next highest, at 100 rpm. The rotation speed corresponding to graph G4 is the highest, at 200 rpm. These graphs G1 to G4 can be obtained by simulation or experiment.

[0190] The amount of pure water present on the main surface of the substrate W (pure water film amount) can be obtained by integrating the thickness of the liquid film in each graph. Therefore, the correspondence relationship between the rotation speed of the substrate W and the pure water film amount can be obtained in advance. Correspondence relationship information D2 indicating this correspondence relationship is stored in the storage unit 603 (see also FIG. 12). Since the rotation speed at the start of the 31st step is included in the recipe information D1, the pure water film amount can be obtained based on this rotation speed and the correspondence relationship information D2.

[0191] The graph may also depend on the flow rate of pure water in the 30th step before the puddle treatment. Therefore, a graph may be created for each flow rate in advance through simulation or experiment, and the pure water film volume may be calculated from the graph. In this case, the correspondence information D2 includes the correspondence between the combination of rotation speed and pure water flow rate and the pure water film volume.

[0192] Next, the solvent discharge amount will be explained. For simplicity, the solvent discharge amount can be considered to be equal to the discharge amount of organic solvent supplied to the substrate W during the discharge period. The discharge amount of organic solvent during the discharge period can be calculated as the time integral of the solvent flow rate of the organic solvent. In other words, the solvent discharge amount can be calculated as the sum of the products of the solvent flow rate of the organic solvent and the required time (discharge time) for each process. In the example of Table 1, the solvent discharge amount is expressed as 100 × (4 + 3) / 60. Note that since the organic solvent can evaporate, the time integral value may be reduced by a predetermined percentage to calculate the solvent discharge amount in consideration of this evaporation.

[0193] Table 2 is a table that schematically shows a second example of the recipe information D1.

[0194] [Table 2]

[0195] Table 2 also shows some of the steps in the processing performed on the substrate W. Fig. 15 is a diagram schematically showing an example of the state of the processing unit 4 in each step in Table 2. Fig. 15(a) to Fig. 15(e) show an example of the state of the processing unit 4 in the 30th step to the 34th step in Table 2, respectively.

[0196] In the 30th step in Table 2, the spin chuck 41 rotates the substrate W at 1500 rpm for four seconds, while the rinse liquid nozzle 43b discharges pure water toward the substrate W at 2000 mL / min. Also, in the 30th step, the cup 42A is used. That is, as shown in FIG. 15(a), in the 30th step, pure water splashed from the periphery of the substrate W is received by the cup 42A.

[0197] In the 31st step, the spin chuck 41 rotates the substrate W at 1500 rpm for two seconds, while the rinse liquid nozzle 43b ejects pure water toward the substrate W at 2000 mL / min. Also, in the 31st step, the cup lifting mechanism 425 switches the cup being used from cup 42C to cup 42A (see FIG. 15(b)). As a result, the pure water is received by cup 42C and flows into the upstream end of the recovery pipe 51.

[0198] In the 32nd step, the spin chuck 41 rotates the substrate W at 1500 rpm for 0.2 seconds, while the rinse liquid nozzle 43b discharges pure water at 2000 mL / min toward the substrate W and the IPA nozzle 43c discharges an organic solvent at 250 mL / min toward the substrate W. As shown in FIG. 15(c), in the 32nd step as well, the processing liquid splashed from the periphery of the substrate W is received in the cup 42C.

[0199] In step 33, the spin chuck 41 rotates the substrate W at 1500 rpm for 30 seconds, while the IPA nozzle 43c ejects the organic solvent at 250 mL / min toward the main surface of the substrate W. As shown in Fig. 15(d), in step 33 as well, the processing liquid splashed from the periphery of the substrate W is collected in the cup 42C. Through steps 32 and 33, the pure water on the main surface of the substrate W is replaced with the organic solvent.

[0200] In step 34, the spin chuck 41 rotates the substrate W at 1500 rpm for 30 seconds. In step 34, no processing liquid is supplied to the substrate W. As shown in FIG. 15(e), in step 34, the organic solvent scattered from the periphery of the substrate W is also collected by the cup 42C. In step 34, the substrate W is dried.

[0201] As described above, in steps 31 to 34, the cup 42C receives the processing liquid (pure water and organic solvent) splashed from the periphery of the substrate W. The processing liquid flows into the upstream end of the recovery pipe 51. Hereinafter, the period from step 31 to step 34 in Table 2 will be referred to as the discharge period.

[0202] In Table 2, in the 31st and 32nd steps, the rinse liquid nozzle 43b discharges pure water toward the substrate W. Therefore, the discharge amount of pure water is the sum of the amount of pure water present on the main surface of the substrate W at the start of the 31st step (i.e., the amount of pure water film) and the total amount of pure water discharged from the rinse liquid nozzle 43b during the discharge period (hereinafter referred to as the pure water discharge amount). The start of the 31st step can also be said to be the start time of switching from cup 42A to cup 42C.

[0203] As described above, the amount of pure water film depends on the rotation speed of the substrate W. Fig. 16 is a graph showing an example of the distance from the center of the substrate W to each position on the substrate W and the thickness of the liquid film at each position. Graph G5 is shown in Fig. 16. The rotation speed of the substrate W corresponding to graph G5 is 1500 rpm. Information on the amount of pure water film when the rotation speed of the substrate W is 1500 rpm is included in the correspondence information D2.

[0204] The graph may also depend on the pure water flow rate in the 30th step before the cup switching step. Therefore, a graph may be created for each flow rate in advance, and the pure water film volume may be calculated from the graph. In this case, the correspondence information D2 includes the correspondence between the combination of the rotation speed and the pure water flow rate and the pure water film volume.

[0205] The pure water discharge amount is the total amount of pure water discharged onto the substrate W during the discharge period. The pure water discharge amount can be calculated as the time integral of the pure water flow rate. In other words, the pure water discharge amount can be calculated as the sum of the products of the pure water flow rate and the required time (discharge time) for each process. In the example of Table 2, the pure water discharge amount is expressed as 2000 x (2 + 0.2) / 60.

[0206] The solvent discharge amount can be considered to be equal to the amount of organic solvent discharged onto the substrate W during the discharge period. The amount of organic solvent discharged during the discharge period can be calculated as the time integral of the solvent flow rate. In the example of Table 2, the amount of pure water discharged is expressed as 250 x (0.2 + 30) / 60. The solvent discharge amount may also be calculated by reducing the time integral by a predetermined percentage.

[0207] 17 is a flowchart showing an example of the operation of the concentration estimation unit 601. First, the concentration estimation unit 601 reads out the recipe information D1 from the storage unit 603 (step S21: reading step).

[0208] Next, the concentration estimation unit 601 calculates the amount of pure water film based on the recipe information D1 (step S22: pure water film amount calculation step). Specifically, the concentration estimation unit 601 identifies the process (e.g., the 31st process in Table 1 or Table 2) at which use of the cup 42C begins from the recipe information D1, and identifies the rotation speed of the substrate W at the start of the process from the recipe information D1. The concentration estimation unit 601 may identify the rotation speed of the substrate W in the process as the rotation speed of the substrate W at the start of the process, or may identify the rotation speed of the substrate W in the process immediately preceding the process. Next, the concentration estimation unit 601 reads out the correspondence relationship information D2 from the storage unit 603. Then, the concentration estimation unit 601 calculates the amount of pure water film (see FIG. 13(c) or FIG. 15(b)) based on the identified rotation speed and the correspondence relationship information D2.

[0209] In addition, if the correspondence information D2 includes a correspondence relationship between the combination of the rotation speed and pure water flow rate of the substrate W and the pure water film amount, the concentration estimation unit 601 may identify the pure water flow rate immediately before the process in which use of the cup 42C begins from the recipe information D1, and calculate the pure water film amount based on the identified rotation speed and pure water flow rate and the correspondence information D2.

[0210] The concentration estimation unit 601 also obtains the total amount of pure water discharged during the discharge period (pure water discharge amount) for the recipe information D1 (step S23: pure water discharge amount calculation step). Specifically, the concentration estimation unit 601 identifies the process in which the cup 42C is used and pure water is discharged from the recipe information D1, and calculates the discharge amount of pure water for that process by multiplying the pure water flow rate by the required time. The concentration estimation unit 601 then calculates the sum of the discharge amounts for each process as the pure water discharge amount.

[0211] Furthermore, the concentration estimation unit 601 obtains the total amount of organic solvent discharged during the discharge period (solvent discharge amount) for the recipe information D1 (step S24: solvent discharge amount calculation step). Specifically, the concentration estimation unit 601 identifies the process in which the cup 42C is used and the organic solvent is discharged from the recipe information D1, and calculates the amount of organic solvent discharged in that process by multiplying the solvent flow rate by the required time. The concentration estimation unit 601 then calculates the sum of the discharge amounts in each process as the solvent discharge amount. The concentration estimation unit 601 may also calculate a value obtained by subtracting a predetermined percentage from the sum as the solvent discharge amount.

[0212] Next, the concentration estimation unit 601 calculates the solvent concentration by dividing the solvent discharge amount by the sum of the pure water film amount, the pure water discharge amount, and the solvent discharge amount (step S25: solvent concentration calculation step).

[0213] As described above, the concentration estimation unit 601 calculates the solvent concentration based on the recipe information D1, which eliminates the need for a concentration sensor for measuring the solvent concentration, thereby reducing the manufacturing cost of the substrate processing apparatus 100.

[0214] In the above example, the concentration estimation unit 601 determines the pure water film amount based on the rotation speed of the substrate W, and calculates the solvent concentration based on the determined pure water film amount, the time integral of the pure water flow rate of the pure water, and the time integral of the solvent flow rate of the organic solvent. Therefore, the concentration estimation unit 601 can determine the solvent concentration with higher accuracy. When the concentration estimation unit 601 determines the pure water film amount based on the flow rate of the pure water and the rotation speed of the substrate W, the solvent concentration can be determined with even higher accuracy.

[0215] In some cases, the recovery pipe connected to the cup 42C branches into multiple pipes for different types of processing liquid. For example, when the cup 42C is used for an organic solvent and another first processing liquid, the cup 42C is connected to a recovery pipe 51 for the organic solvent and a recovery pipe for the first processing liquid. A switching valve unit is also provided. The switching valve unit connects the pipe for the first processing liquid to the cup 42C when the first processing liquid is being supplied to the substrate W, and connects the recovery pipe 51 to the cup 42C when the organic solvent is being supplied to the substrate W. In this case, multiple discharge ports are set in the cup 42C. In this case, the discharge ports may be set in the recipe information D1. The concentration estimation unit 601 may then identify a process in which a discharge port for the organic solvent (i.e., the recovery pipe 51) is set, and calculate the pure water film amount, the pure water discharge amount, and the solvent discharge amount in the same manner as described above.

[0216] <Measurement of solvent concentration using a concentration sensor> In the above example, the control unit 6 calculates the solvent concentration of the mixed solution discharged from the processing unit 4 based on the recipe information D1. However, this is not necessarily limited to this. The solvent concentration of the mixed solution discharged from the processing unit 4 may be measured by a concentration sensor.

[0217] 18 is a diagram schematically illustrating a second example of the substrate processing apparatus 100 according to the fourth embodiment. In the second example, a concentration sensor Sn5 is provided in each common recovery pipe 510. The concentration sensor Sn5 measures the solvent concentration of the mixed liquid flowing through the common recovery pipe 510 and outputs the measurement result to the control unit 6. The concentration sensor Sn5 may be a conductivity type concentration sensor, an optical type concentration sensor, or an ultrasonic type concentration sensor.

[0218] The control unit 6 controls the recovery destination switching unit 50 based on the solvent concentration measured by the concentration sensor Sn5. Specifically, the control unit 6 compares the solvent concentration measured by the concentration sensor Sn5 with a switching reference value, and when the solvent concentration is less than the switching reference value, causes the recovery destination switching unit 50 to select the second spinning state, and when the solvent concentration is equal to or greater than the switching reference value, causes the recovery destination switching unit 50 to select the first spinning state.

[0219] According to the second example, the concentration sensor Sn5 measures the solvent concentration, so the control unit 6 can obtain the solvent concentration of the mixed liquid with higher accuracy. Therefore, the control unit 6 can more appropriately control the recovery destination switching unit 50, and more appropriately supply the mixed liquid to the first dehydrator 60 or the second dehydrator 70.

[0220] <Fifth embodiment> 19 is a diagram schematically illustrating an example of a substrate processing apparatus 100 according to the fifth embodiment. The substrate processing apparatus 100 according to the fifth embodiment differs from the substrate processing apparatus 100 according to the fourth embodiment in the configuration of the recovery destination switching unit 50.

[0221] The recovery destination switching unit 50 switches between a first spinning state and a second spinning state. In the fifth embodiment, the first spinning state is a state in which the mixed liquid obtained by combining the mixed liquids from the plurality of processing units 4 is supplied to the first dehydrator 60, and the second spinning state is a state in which the mixed liquid obtained by combining the mixed liquids from the plurality of processing units 4 is supplied to the second dehydrator 70.

[0222] The recovery destination switching unit 50 includes a recovery pipe 51 and a switching valve unit 520. The recovery pipe 51 includes a common recovery pipe 517, a first dehydration pipe 518, and a second dehydration pipe 519. The common recovery pipe 517 is connected to each processing unit 4 (cup 42) through each cup-side recovery pipe 424. In the common recovery pipe 517, mixed liquids from multiple processing units 4 can merge. The downstream end of the common recovery pipe 517 is connected to the upstream end of the first dehydration pipe 518 and the upstream end of the second dehydration pipe 519. The downstream end of the first dehydration pipe 518 is connected to the first dehydrator 60, and the downstream end of the second dehydration pipe 519 is connected to the second dehydrator 70.

[0223] 19, switching valve unit 520 includes switching valve 523 and switching valve 524. Switching valve unit 520 switches between a state in which common recovery pipe 517 communicates with first dehydrator 60 (first spinning state) and a state in which common recovery pipe 517 communicates with second dehydrator 70 (second spinning state). In the example of FIG. 19, switching valve 523 is inserted in first dehydration pipe 518, and switching valve 524 is inserted in second dehydration pipe 519.

[0224] When the control unit 6 closes the switching valve 523 and opens the switching valve 524, the mixed liquid from the processing unit 4 flows through the common recovery pipe 517 and the second dehydration pipe 519 in this order and is supplied to the second dehydrator 70. When the control unit 6 opens the switching valve 523 and closes the switching valve 524, the mixed liquid from the processing unit 4 flows through the common recovery pipe 517 and the first dehydration pipe 518 in this order and is supplied to the first dehydrator 60.

[0225] The control unit 6 controls the recovery destination switching unit 50 based on the solvent concentration of the mixed liquid flowing through the common recovery pipe 517. In the example of FIG. 19, the common recovery pipe 517 is provided with a concentration sensor Sn51. The concentration sensor Sn51 measures the solvent concentration of the mixed liquid flowing through the common recovery pipe 517 and outputs the measurement result to the control unit 6. An example of the configuration of the concentration sensor Sn51 is the same as that of the concentration sensor Sn5. The control unit 6 causes the recovery destination switching unit 50 to select the second spinning state when the solvent concentration measured by the concentration sensor Sn51 is a second value less than the concentration lower limit of the first separation membrane 62c, and causes the recovery destination switching unit 50 to select the first spinning state when the solvent concentration is a first value equal to or greater than the concentration lower limit of the first separation membrane 62c. As a more specific example, the control unit 6 may compare the solvent concentration measured by the concentration sensor Sn51 with a switching reference value. The control unit 6 causes the recovery destination switching unit 50 to select the second spinning state when the solvent concentration is less than the switching reference value, and causes the recovery destination switching unit 50 to select the first spinning state when the solvent concentration is equal to or greater than the switching reference value.

[0226] As described above, according to the fifth embodiment, the organic solvent recovery section 5 switches the supply destination of the mixed liquid obtained by joining the mixed liquids from the plurality of processing units 4, based on the solvent concentration of the mixed liquid. That is, in the fifth embodiment, a single recovery destination switching section 50 is provided corresponding to the plurality of processing units 4. Therefore, compared to the fourth embodiment in which a plurality of recovery destination switching sections 50 are provided in a one-to-one correspondence with the plurality of processing units 4, the manufacturing cost of the organic solvent recovery section 5 can be reduced.

[0227] Furthermore, in the above example, the concentration sensor Sn51 measures the solvent concentration, so the control unit 6 can obtain the solvent concentration of the mixed solution with higher accuracy. This allows the control unit 6 to more appropriately control the recovery destination switching unit 50 and more appropriately supply the mixed solution to the first dehydrator 60 or the second dehydrator 70. Moreover, according to the fifth embodiment, a single concentration sensor Sn51 is provided corresponding to multiple processing units 4. This allows for a reduction in the manufacturing cost of the organic solvent recovery unit 5 compared to the fourth embodiment in which multiple concentration sensors Sn5 are provided one-to-one with multiple processing units 4.

[0228] As described above, the organic solvent recovery apparatus (organic solvent recovery unit 5), the substrate processing apparatus 100, and the organic solvent recovery method have been described in detail. However, the above description is merely an example in all respects, and this disclosure is not limited thereto. Furthermore, the various modifications described above can be applied in combination as long as they are not mutually contradictory. Furthermore, it is understood that many modifications not exemplified can be envisioned without departing from the scope of this disclosure.

[0229] For example, the organic solvent recovery unit 5 may include a filter that captures impurities in the recycled liquid. For example, the organic solvent recovery unit 5 may include a purification tank, a purified circulation pipe connected to the purification tank, and a switching valve, a pump, and a filter inserted in the purified circulation pipe. This allows the organic solvent recovery unit 5 to supply recycled liquid with a low impurity concentration to the supply tank Tk3. [Explanation of symbols]

[0230] 100 Substrate processing apparatus 4 Processing Unit 41 Substrate holder (spin chuck) 42 cups 430 Discharge part 50 Collection destination switching unit 51 Recovery piping 6 Control Unit 60 1st dehydrator 62 1st membrane separator 62c 1st separation membrane 63 1st circulation piping 630 First individual piping 64,74 Liquid delivery unit (pump) 672 Common circulation piping (upstream common piping) 70 Second dehydrator 701 Distillation tower 704 Ultrasonic Atomization Separator 72 Second membrane separator 72c 2nd separation membrane 73 2nd circulation piping 730 No. 2 individual piping 78 First liquid supply pipe 790 Switching valve section 85 Second liquid supply pipe D1 Recipe Information D2 Correspondence information Sn5, Sn51 concentration sensor Tk1 Concentration Tank Tk3 Supply Tank W substrate

Claims

1. a recovery pipe through which a mixed liquid of organic solvent and water discharged from a processing unit for processing substrates flows; a first dehydrator including a first membrane separator having a solvent concentration range, the first membrane separator separating water from the mixed solution having a solvent concentration equal to or higher than a lower limit of the solvent concentration range, thereby increasing the solvent concentration of the mixed solution; a second dehydrator provided upstream of the first dehydrator, which separates water from the mixed liquid discharged through the recovery pipe, increases the solvent concentration of the mixed liquid to the concentration lower limit value or more, and supplies the mixed liquid having a solvent concentration equal to or higher than the concentration lower limit value to the first dehydrator; An organic solvent recovery apparatus comprising:

2. The organic solvent recovery apparatus according to claim 1, the second dehydrator includes a first liquid supply pipe through which the mixed liquid flows toward the first dehydrator; the first dehydrator includes a second liquid transfer pipe through which the mixed liquid flows toward a supply tank for supply to the processing unit; the first membrane separator is connected to a downstream end of the first liquid transfer pipe and an upstream end of the second liquid transfer pipe.

3. The organic solvent recovery apparatus according to claim 1, The first dehydrator is a concentration tank for storing the mixed liquid; a first circulation pipe connected to the concentration tank and provided with the first membrane separator; a liquid delivery section provided in the first circulation pipe; An organic solvent recovery device comprising:

4. The organic solvent recovery apparatus according to any one of claims 1 to 3, The organic solvent recovery apparatus, wherein the second dehydrator includes at least one of a distillation column and an ultrasonic atomization separator.

5. The organic solvent recovery apparatus according to claim 1 or 2, the second dehydrator includes a second membrane separator having a second separation membrane; the lower limit of the solvent concentration range of the second separation membrane is less than the lower limit of the solvent concentration of the first separation membrane; The organic solvent recovery apparatus, wherein the separation constant of the first separation membrane is higher than the separation constant of the second separation membrane.

6. The organic solvent recovery apparatus according to claim 5, The second dehydrator is a concentration tank that stores the mixed liquid flowing in from the recovery pipe; a second circulation pipe connected to the concentration tank and equipped with the second membrane separator; a liquid delivery section provided in the second circulation pipe; An organic solvent recovery device comprising:

7. The organic solvent recovery apparatus according to claim 6, Further provided with a switching valve section, the first dehydrator includes a first circulation pipe connected to the concentration tank; The first circulation pipe is a common circulation pipe provided with the liquid delivery unit; a first individual pipe provided with the first membrane separator; Including, The second circulation pipe is the common circulation pipe; a second individual pipe provided with the second membrane separator; and Including, The switching valve unit switches between a first circulation state in which the mixed liquid circulates through the concentration tank and the first circulation piping, and a second circulation state in which the mixed liquid circulates through the concentration tank and the second circulation piping.

8. The organic solvent recovery apparatus according to claim 7, a control unit that causes the switching valve unit to select the second circulation state when the solvent concentration of the mixed solution is a second value that is less than the concentration lower limit value of the first separation membrane, and that causes the switching valve unit to select the first circulation state when the solvent concentration of the mixed solution is a first value that is equal to or greater than the concentration lower limit value.

9. The organic solvent recovery apparatus according to any one of claims 1 to 3, a recovery destination switching unit that switches between a second dehydration state in which the mixed liquid discharged from the processing unit is supplied to the second dehydrator and a first dehydration state in which the mixed liquid discharged from the processing unit is supplied to the first dehydrator, bypassing the second dehydrator; a control unit that causes the recovery destination switching unit to select the second dehydration state when the solvent concentration of the mixed liquid is a second value that is less than the concentration lower limit value of the first separation membrane, and that causes the recovery destination switching unit to select the first dehydration state when the solvent concentration of the mixed liquid is a first value that is equal to or greater than the concentration lower limit value; The organic solvent recovery device further comprises:

10. The organic solvent recovery apparatus according to claim 9, a storage unit that stores recipe information indicating processing details for the substrate by the processing unit; The control unit calculates the solvent concentration of the mixed liquid discharged from the processing unit based on the recipe information.

11. The organic solvent recovery apparatus according to claim 10, The processing unit a substrate holder that holds and rotates the substrate; a discharge unit that sequentially discharges pure water and an organic solvent onto a main surface of the substrate held by the substrate holder; a cup having a cylindrical shape surrounding the substrate holding part and configured to receive liquid splashed from the periphery of the substrate; Including, an upstream end of the recovery pipe connected to the cup; The recipe information includes a flow rate and a discharge time of the pure water to be discharged onto the substrate, a solvent flow rate and a discharge time of the organic solvent to be discharged onto the substrate, and a rotation speed of the substrate; the storage unit stores correspondence relationship information indicating a correspondence relationship between the rotation speed and a pure water film amount, which is the amount of pure water on the main surface of the substrate; the control unit determines the pure water film amount based on the rotation speed of the substrate specified based on the recipe information and the correspondence information, and calculates the solvent concentration of the mixed solution discharged from the processing unit based on the pure water film amount, a time integral value of the pure water flow rate, and a time integral value of the solvent flow rate.

12. The organic solvent recovery apparatus according to claim 9, a concentration sensor for measuring a solvent concentration of the mixed liquid; The control unit controls the recovery destination switching unit based on the solvent concentration of the mixed liquid measured by the concentration sensor.

13. The organic solvent recovery apparatus according to any one of claims 1 to 3, A collection destination switching unit; a control unit that controls the recovery destination switching unit; Equipped with The recovery pipe is a plurality of cup-side recovery pipes connected to a plurality of the processing units; a common recovery pipe connected to downstream ends of the plurality of cup-side recovery pipes; a first dehydration pipe connecting a downstream end of the common recovery pipe to the first dehydrator; a second dehydration pipe connecting the downstream end of the common recovery pipe and the second dehydrator; Including, the recovery destination switching unit switches between a first dehydration state in which the common recovery pipe is connected to the first dehydrator through the first dehydrator and the mixed liquid is supplied to the first dehydrator bypassing the second dehydrator, and a second dehydration state in which the common recovery pipe is connected to the second dehydrator through the second dehydration pipe and the mixed liquid is supplied to the second dehydrator; the control unit causes the recovery destination switching unit to select the first dehydration state when the solvent concentration of the mixed liquid flowing through the common recovery pipe is a first value that is equal to or greater than the concentration lower limit value of the first separation membrane, and causes the recovery destination switching unit to select the second dehydration state when the solvent concentration of the mixed liquid flowing through the common recovery pipe is a second value that is less than the concentration lower limit value.

14. The organic solvent recovery apparatus according to any one of claims 1 to 3; the processing unit; A substrate processing apparatus comprising:

15. a first step of separating water from a mixed solution of an organic solvent and water discharged from a processing unit for processing a substrate, thereby increasing the solvent concentration of the mixed solution; a second step, after the first step, of separating water from the mixed solution using a first membrane separator including a first separation membrane having an applicable range of solvent concentrations to increase the solvent concentration of the mixed solution; Equipped with In the first step, the solvent concentration of the mixed solution is increased to or above a lower limit concentration value that is a lower limit value of the application range of the first separation membrane.

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