Organic solvent recovery device, substrate processing system, 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 first pipe, a second pipe, a merging part 50, and a first dehydrator 60. A mixed liquid containing an organic solvent and water from a first processing unit 4 for processing a substrate W flows through the first pipe. The organic solvent or the mixed liquid flows through the second pipe. The merging part 50 merges the mixed liquid having the solvent concentration lower than a predetermined concentration reference value via the first pipe and the liquid having the solvent concentration equal to or higher than the concentration reference value via the second pipe to generate a merged mixed liquid which is a mixed liquid having the solvent concentration equal to or higher than the concentration reference value. The first dehydrator 60 includes a first separation membrane 62c in which the lower limit value of the application range of the solvent concentration is the concentration reference value, and includes a first membrane separator 62 that separates water from the merged mixed liquid from the merging part 50 to increase the solvent concentration of the merged mixed liquid.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to an organic solvent recovery apparatus, a substrate processing system, 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 first pipe through which a mixed liquid containing an organic solvent and water flows from a first processing unit that processes substrates; a second pipe through which the organic solvent or the mixed liquid flows; a confluence section that combines the mixed liquid having a solvent concentration below a predetermined concentration standard value that has passed through the first pipe with a liquid having a solvent concentration equal to or greater than the concentration standard value that has passed through the second pipe to produce a combined mixed liquid that is the mixed liquid having a solvent concentration equal to or greater than the concentration standard value; and a first dehydrator that includes a first separation membrane whose lower limit concentration value of an applicable range of solvent concentrations is the concentration standard value, and that separates water from the combined mixed liquid from the confluence section to increase the solvent concentration of the combined mixed liquid.

[0008] A second aspect is an organic solvent recovery apparatus according to the first aspect, further comprising a third pipe through which the mixed liquid discharged from a second processing unit for processing a substrate flows, the liquid being a new liquid of the organic solvent that has not yet been used in processing the substrate, and the confluence section including an adjuster for adjusting the confluence ratio of the mixed liquid that has passed through the first pipe, the mixed liquid that has passed through the third pipe, and the new liquid that has passed through the second pipe.

[0009] A third aspect is the organic solvent recovery apparatus according to the second aspect, wherein the confluence unit includes a first confluence tank and a second confluence tank, a recovery destination switching unit that switches the recovery destination of the mixed liquid through the first piping and the third piping between the first junction tank and the second junction tank, a new liquid switching unit that switches the supply destination of the new liquid between the first junction tank and the second junction tank, and a supply source switching unit that switches the supply source that supplies the mixed liquid to the first dehydrator between the first junction tank and the second junction tank.

[0010] A fourth aspect is an organic solvent recovery apparatus according to the first aspect, comprising: a low-concentration tank; a high-concentration tank; a first recovery destination switching unit that switches between a first low-concentration state in which the first processing unit is connected to the low-concentration tank and a first high-concentration state in which the first processing unit is connected to the high-concentration tank; and a control unit that causes the first recovery destination switching unit to select the first low-concentration state when the solvent concentration of the mixed liquid from the first processing unit is less than the concentration reference value, and causes the first recovery destination switching unit to select the first high-concentration state when the solvent concentration of the mixed liquid from the first processing unit is equal to or greater than the concentration reference value, wherein the first piping connects the low-concentration tank and the confluence, and the second piping connects the high-concentration tank and the confluence, and the confluence includes an adjuster that adjusts the confluence ratio of the mixed liquid passing through the first piping and the mixed liquid passing through the second piping.

[0011] A fifth aspect is an organic solvent recovery apparatus according to the fourth aspect, further comprising a new liquid pipe through which new organic solvent that has not yet been used in processing the substrate flows, the confluence section mixes the mixed liquid that has passed through the first pipe from the low-concentration tank, the mixed liquid that has passed through the second pipe from the high-concentration tank, and the new liquid that has passed through the new liquid pipe, and the adjuster adjusts the confluence ratio of the mixed liquid that has passed through the first pipe, the mixed liquid that has passed through the second pipe, and the new liquid that has passed through the new liquid pipe.

[0012] A sixth aspect is an organic solvent recovery apparatus according to the fourth or fifth aspect, further comprising a second recovery destination switching unit that switches between a second low-concentration state in which a second processing unit that processes a substrate is connected to the low-concentration tank and a second high-concentration state in which the second processing unit is connected to the high-concentration tank, and the control unit causes the second recovery destination switching unit to select the second low-concentration state when the solvent concentration of the mixed liquid from the second processing unit is less than the concentration reference value, and causes the second recovery destination switching unit to select the second high-concentration state when the solvent concentration of the mixed liquid from the second processing unit is greater than or equal to the concentration reference value.

[0013] A seventh aspect is an organic solvent recovery apparatus according to any one of the fourth to sixth aspects, comprising a memory unit storing recipe information indicating the processing details to be performed on the substrate by the first processing unit, and the control unit calculating the solvent concentration of the mixed liquid discharged from the first processing unit based on the recipe information.

[0014] An eighth aspect is the organic solvent recovery apparatus according to the seventh aspect, wherein the first 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, an upstream end of the first pipe is connected to the cup, the recipe information includes a pure water flow rate and discharge time of the pure water to be discharged onto the substrate, a solvent flow rate and discharge time of the organic solvent to be discharged onto the substrate, and a rotation speed of the substrate, the memory part stores correspondence information indicating 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 calculates 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 first 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.

[0015] A ninth aspect is an organic solvent recovery device according to the fourth aspect, further comprising a concentration sensor for measuring the solvent concentration of the mixed liquid, and the control unit controls the first recovery destination switching unit based on the solvent concentration of the mixed liquid measured by the concentration sensor.

[0016] A tenth aspect is an organic solvent recovery apparatus according to any one of the first to ninth aspects, wherein the confluence section includes a tank into which the mixed liquid flows after passing through each of the first pipe and the second pipe, and an agitation section that agitates the mixed liquid stored in the tank.

[0017] An eleventh aspect is the organic solvent recovery apparatus according to the tenth aspect, wherein the stirring unit includes a bubbler tube that discharges bubbles into the mixed liquid stored in the tank.

[0018] A twelfth aspect is the organic solvent recovery apparatus according to the tenth aspect, wherein the stirring unit includes a stirring circulation pipe connected to the tank, and the mixed liquid is circulated through the tank and the stirring circulation pipe.

[0019] A thirteenth aspect is an organic solvent recovery apparatus according to any one of the first to twelfth aspects, further comprising a second dehydrator that separates water from the mixed liquid flowing through one of the first pipe and the second pipe to increase the solvent concentration of the mixed liquid, and the confluence section merges the mixed liquid that has passed through the other of the first pipe and the second pipe with the mixed liquid from the second dehydrator.

[0020] A fourteenth aspect is the organic solvent recovery apparatus according to the thirteenth aspect, wherein the second dehydrator includes at least one of a distillation column and an ultrasonic atomization separator.

[0021] A fifteenth aspect is the organic solvent recovery apparatus according to the thirteenth aspect, wherein the second dehydrator includes a second membrane separator that includes a second separation membrane and separates water from the mixed liquid to increase the solvent concentration of the mixed liquid, and the concentration lower limit value of the second separation membrane is different from the concentration lower limit value of the first separation membrane.

[0022] A sixteenth aspect is the organic solvent recovery apparatus according to the fifteenth aspect, further comprising a third dehydrator provided upstream of the second dehydrator, wherein the third dehydrator separates water from the mixed liquid flowing through one of the first pipe and the second pipe, increases the solvent concentration of the mixed liquid to or above the lower limit concentration value of the second separation membrane, and supplies the mixed liquid to the second dehydrator.

[0023] A seventeenth aspect is the organic solvent recovery apparatus according to the fifteenth aspect, wherein the second dehydrator includes: a concentration tank that stores the mixed liquid from the first pipe or the second pipe; a second circulation pipe connected to the concentration tank and provided with the second membrane separator; a third circulation pipe connected to the concentration tank and provided with a third membrane separator; a circulation switching unit that switches between a second circulation state in which the mixed liquid circulates through the concentration tank and the second circulation pipe and a third circulation state in which the mixed liquid circulates through the concentration tank and the third circulation pipe; and a control unit, The three-membrane separator includes a third separation membrane, the concentration lower limit value of the third separation membrane is lower than the concentration lower limit value of the second separation membrane, and the separation constant of the second separation membrane is higher than the separation constant of the third separation membrane, and the control unit causes the circulation switching unit to select the third circulation state when the solvent concentration of the mixed liquid in the concentration tank is lower than the concentration lower limit value of the second separation membrane and equal to or greater than the concentration lower limit value of the third separation membrane, and causes the circulation switching unit to select the second circulation state when the solvent concentration of the mixed liquid in the concentration tank is equal to or greater than the concentration lower limit value of the second separation membrane.

[0024] An eighteenth aspect is a substrate processing system comprising: an organic solvent recovery apparatus according to any one of the second, third, and sixth aspects; a first substrate processing apparatus including a first load port, a plurality of the first processing units, and a first transport part that transports substrates between the first load port and the plurality of first processing units; and a second substrate processing apparatus including a second load port, a plurality of the second processing units, and a second transport part that transports substrates between the second load port and the plurality of second processing units.

[0025] A nineteenth aspect is an organic solvent recovery method, comprising a confluence step of confluence of a mixed liquid containing an organic solvent and water discharged from a first processing unit for processing substrates with the organic solvent or the mixed liquid to produce the mixed liquid having a concentration equal to or greater than a standard value, and a dehydration step of separating water from the mixed liquid produced by the confluence step using a first membrane separator including a first separation membrane whose lower limit value of the applicable range of solvent concentration is the standard value, thereby increasing the solvent concentration of the mixed liquid. [Effects of the Invention]

[0026] According to the first, eighteenth, and nineteenth aspects, the confluence unit combines the mixed liquid having a solvent concentration below the concentration reference value, which has passed through the first pipe, with the mixed liquid having a solvent concentration equal to or greater than the concentration reference value, which has passed through the second pipe, to produce a combined mixed liquid having a solvent concentration equal to or greater than the concentration reference value. Because the solvent concentration of the combined mixed liquid is equal to or greater than the lower limit of the first separation membrane, the first dehydrator can reliably increase the solvent concentration of the combined mixed liquid. Furthermore, because the energy efficiency of membrane separation is higher than that of other methods, the first dehydrator can more efficiently increase the solvent concentration of the combined mixed liquid. In other words, the organic solvent recovery device can separate water from the mixed liquid with high reliability and efficiency.

[0027] According to the second aspect, even if the mixed liquid having a concentration equal to or greater than the reference value flowing through the third pipe is insufficient, the confluence section can generate a combined mixed liquid having a concentration equal to or greater than the reference value using new liquid.

[0028] According to the third aspect, the recovery destination switching unit can alternately switch the recovery destination between the first junction tank and the second junction tank, so that the mixed liquid can be constantly recovered from the first processing unit and the second processing unit.

[0029] During the period when the first junction tank is collecting the mixed liquid from the first processing unit and the second processing unit, the new liquid switching unit can select the second junction tank as the supply destination of the new liquid. Therefore, during this period, new liquid can be supplied to the second junction tank, ensuring that the solvent concentration of the mixed liquid in the second junction tank is equal to or greater than the concentration reference value. Furthermore, since the mixed liquid from the first processing unit and the second processing unit flows into the first junction tank but not into the second junction tank, it is easy to adjust the concentration in the second junction tank. Furthermore, by the supply source switching unit selecting the second junction tank as the supply source, the combined mixed liquid in the second junction tank can be supplied to the first dehydrator.

[0030] Similarly, when the second confluence tank is collecting the mixed liquid, the solvent concentration of the mixed liquid in the first confluence tank can be adjusted, and the combined mixed liquid in the first confluence tank can be supplied to the first dehydrator.

[0031] According to a fourth aspect, the mixed liquid from the first processing unit is distributed to a low-concentration tank and a high-concentration tank according to the solvent concentration. Therefore, the low-concentration tank stores a low-concentration mixed liquid whose solvent concentration is below a standard concentration value, and the high-concentration tank stores a high-concentration mixed liquid whose solvent concentration is equal to or greater than the standard concentration value. The adjuster adjusts the merging ratio of the low-concentration mixed liquid from the low-concentration tank and the high-concentration mixed liquid from the high-concentration tank, so that the merging section can more reliably produce a merging mixed liquid whose concentration is equal to or greater than the standard concentration value.

[0032] According to the fifth aspect, the confluence unit can confluence new liquid when the high-concentration mixed liquid in the high-concentration tank is insufficient, thereby more reliably producing a mixed liquid having a concentration equal to or higher than the reference value.

[0033] According to the sixth aspect, the mixed solution from the second treatment tank can also be distributed between the low-concentration tank and the high-concentration tank, thereby reducing the possibility of the mixed solution running short in the high-concentration tank.

[0034] According to the seventh aspect, there is no need to provide a concentration sensor, and therefore manufacturing costs can be reduced.

[0035] According to the eighth aspect, the solvent concentration can be calculated with high accuracy.

[0036] According to the ninth aspect, the solvent concentration can be obtained with high accuracy.

[0037] According to the tenth aspect, the concentration distribution of the mixed liquid can be made more uniform, so that the mixed liquid having a concentration equal to or higher than the lower limit value of the first separation membrane can be more reliably caused to flow into the first membrane separator.

[0038] According to the eleventh aspect, since there is no need to provide a drive unit such as a screw inside the tank, it is possible to suppress an increase in the concentration of impurities in the mixed liquid.

[0039] According to the twelfth aspect, since there is no need to provide a drive unit such as a screw inside the tank, an increase in the impurity concentration in the mixed liquid can be suppressed.

[0040] According to the thirteenth aspect, a mixed liquid having a concentration equal to or greater than the reference value can be more reliably produced.

[0041] According to the fourteenth aspect, the lower limit of the concentration of the second dehydrator is low, and therefore it is easily applicable to the mixed liquid that has passed through the first pipe.

[0042] According to the fifteenth aspect, the energy efficiency of membrane separation is high, so that the solvent concentration of the mixed solution can be increased more effectively. In addition, since the lower limit of the concentration of the second separation membrane is different from the lower limit of the concentration of the first separation membrane, the second separation membrane suitable for the solvent concentration of the mixed solution can be used.

[0043] According to the sixteenth aspect, the second dehydrator can increase the solvent concentration of the mixed liquid with higher reliability.

[0044] According to the seventeenth aspect, the solvent concentration of the mixed liquid can be increased with higher reliability and higher efficiency. [Brief explanation of the drawings]

[0045] [Figure 1] FIG. 1 is a diagram schematically illustrating an example of a substrate processing system according to a first embodiment. [Figure 2] FIG. 1 is a plan view schematically illustrating an example of a substrate processing apparatus. [Figure 3] FIG. 2 is a side view schematically illustrating an example of a processing unit. [Figure 4] FIG. 10 is a diagram schematically illustrating another example of the confluence portion. [Figure 5] FIG. 2 is a diagram schematically illustrating an example of a first dehydrator. [Figure 6] 10 is a flowchart showing an example of the operation of the organic solvent recovery unit. [Figure 7] FIG. 10 is a diagram schematically illustrating an example of a junction according to a second embodiment. [Figure 8] FIG. 10 is a diagram for explaining an example of the operation of the organic solvent recovery unit according to the second embodiment. [Figure 9] FIG. 10 is a diagram schematically illustrating an example of an organic solvent recovery unit according to a third embodiment. [Figure 10] 10 is a flowchart showing an example of the operation of the organic solvent recovery unit according to the third embodiment. [Figure 11] 10 is a flowchart showing an example of the operation of the organic solvent recovery unit according to the third embodiment. [Figure 12] FIG. 10 is a diagram schematically illustrating an example of a substrate processing system according to a fourth embodiment. [Figure 13] FIG. 10 is a diagram schematically illustrating an example of a processing unit according to a fourth embodiment. [Figure 14] FIG. 2 is a diagram schematically illustrating an example of the state of a processing unit in each step of Table 1. [Figure 15] 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 16] FIG. 1 is a diagram schematically illustrating an example of the state of a processing unit in each step of Table 2. [Figure 17] 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 18] 10 is a flowchart illustrating an example of an operation of a concentration estimation unit. [Figure 19] FIG. 10 is a diagram schematically illustrating a second example of a substrate processing system according to a fourth embodiment. [Figure 20] FIG. 12 is a diagram schematically illustrating a first example of a first dehydrator according to a fifth embodiment. [Figure 21] 10 is a flowchart showing an example of the operation of the organic solvent recovery unit according to the fifth embodiment. [Figure 22] FIG. 13 is a diagram schematically illustrating a second example of the first dehydrator according to the fifth embodiment. [Figure 23] FIG. 10 is a diagram illustrating an example of a substrate processing system according to a sixth embodiment. [Figure 24] FIG. 2 is a diagram schematically illustrating a first example of a second dehydrator. [Figure 25] FIG. 10 is a diagram schematically illustrating a second example of a second dehydrator. [Figure 26] FIG. 10 is a diagram schematically illustrating a third example of a second dehydrator. [Figure 27] FIG. 13 is a diagram schematically illustrating an example of a substrate processing system according to a seventh embodiment. [Figure 28] FIG. 13 is a diagram schematically illustrating an example of a substrate processing system according to an eighth embodiment. [Figure 29] FIG. 13 is a diagram schematically illustrating an example of an organic solvent recovery unit according to a ninth embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0046] 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.

[0047] 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.

[0048] 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.

[0049] 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.

[0050] First Embodiment <1. Substrate processing equipment> FIG. 1 is a diagram schematically illustrating an example of a substrate processing system 1000 according to a first embodiment. In the example of FIG. 1, the substrate processing system 1000 includes a plurality of substrate processing apparatuses 100, an organic solvent recovery apparatus (organic solvent recovery unit 5), and a control unit 6. In FIG. 1, the plurality of substrate processing apparatuses 100 include a substrate processing apparatus 100A (corresponding to a first substrate processing apparatus) and a substrate processing apparatus 100B (corresponding to a second substrate processing apparatus). The substrate processing apparatus 100A and the substrate processing apparatus 100B may have similar configurations. FIG. 2 is a plan view schematically illustrating an example of the substrate processing apparatus 100.

[0051] 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.

[0052] The substrate processing apparatus 100A includes a load port 1 (corresponding to a first load port), an indexer robot 2 (corresponding to a first transfer section), a main transport robot 3 (corresponding to a first transfer section), and a processing unit 4 (corresponding to a first processing unit). Similarly, the substrate processing apparatus 100B includes a load port 1 (corresponding to a second load port), an indexer robot 2 (corresponding to a second transfer section), a main transport robot 3 (corresponding to a second transfer section), and a processing unit 4 (corresponding to a second processing unit).

[0053] 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.).

[0054] 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.

[0055] 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).

[0056] 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.

[0057] 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.

[0058] The control unit 6 controls the operation of each unit (load port 1, indexer robot 2, main transport robot 3, processing unit 4, and organic solvent recovery unit 5) included in the substrate processing system 1000. 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 unit of the substrate processing apparatus 100 via the control unit 6, and the processing defined by the program may be performed 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.

[0059] <2. Processing unit> The processing unit 4 will be described with reference to Fig. 3. Fig. 3 is a side view schematically showing an example of the processing unit 4.

[0060] <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.

[0061] 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.

[0062] 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.

[0063] 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.

[0064] 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.

[0065] 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).

[0066] 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.

[0067] 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.

[0068] <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.).

[0069] 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.

[0070] 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).

[0071] 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).

[0072] 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.

[0073] 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.

[0074] 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.

[0075] 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.

[0076] <2-3. Discharge of pure water and organic solvents from treatment unit 4> In the above example, the processing unit 4 sequentially supplies pure water and an organic solvent (e.g., IPA) to the main surface of the substrate W, and therefore the pure water and the organic solvent flow into the cup-side recovery pipe 424. That is, a mixture of water and organic solvent may flow into the cup-side recovery pipe 424. The concentration of the organic solvent in the mixture (hereinafter referred to as the solvent concentration) depends on the type of processing performed on the substrate W by the processing unit 4. For example, if the flow rate of pure water supplied to the substrate W is high, the solvent concentration (average value) of the mixture flowing through the cup-side recovery pipe 424 may be low.

[0077] Furthermore, there are cases where almost no pure water is used on the substrate W. For example, there are cases where a metal film (e.g., wiring) is exposed on the main surface of the substrate W. In this case, almost no pure water is used on the substrate W. In this case, the solvent concentration (average value) of the mixed liquid flowing through the cup-side recovery pipe 424 may be high. For example, at the back end of a semiconductor device manufacturing process, wiring is formed on the main surface of the substrate W, and therefore a metal film as wiring may be exposed on the main surface of the substrate W. For this reason, in the back end substrate processing apparatus 100, the solvent concentration of the mixed liquid flowing through the cup-side recovery pipe 424 tends to be high. Conversely, in the front end substrate processing apparatus 100, the solvent concentration of the mixed liquid flowing through the cup-side recovery pipe 424 tends to be low.

[0078] Here, as an example, the substrate processing apparatus 100A is a front-end substrate processing apparatus 100, and the solvent concentration of the mixed liquid discharged from each processing unit 4 of the substrate processing apparatus 100A tends to be relatively low. Also, here, as an example, the substrate processing apparatus 100B is a back-end substrate processing apparatus 100, and the solvent concentration of the mixed liquid discharged from each processing unit 4 of the substrate processing apparatus 100B tends to be relatively high.

[0079] The mixed liquid from each substrate processing apparatus 100 is supplied to the organic solvent recovery unit 5 through recovery pipe 51 (see FIG. 1). Hereinafter, the recovery pipe 51 connected to the substrate processing apparatus 100A will be referred to as recovery pipe 51A, and the recovery pipe 51 connected to the substrate processing apparatus 100B will be referred to as recovery pipe 51B. The recovery pipe 51 is connected to the downstream ends of multiple cup-side recovery pipes 424 of the corresponding substrate processing apparatus 100.

[0080] In the first embodiment, for example, the solvent concentration (average value) of the mixed liquid flowing from the substrate processing apparatus 100A through the recovery pipe 51A is lower than a concentration reference value described below, for example, 30 wt% or less. Also, in the first embodiment, for example, the solvent concentration (average value) of the mixed liquid flowing from the substrate processing apparatus 100B through the recovery pipe 51B is higher than the concentration reference value, for example, 70 wt% or more.

[0081] <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. 1. In the following, first, an overview of the organic solvent recovery section 5 will be described, and then each component of the organic solvent recovery section 5 will be described in detail.

[0082] The organic solvent recovery section 5 includes a confluence section 50 and a first dehydrator 60. The confluence section 50 merges the mixed liquid that has passed through the recovery pipe 51A (corresponding to the first pipe) and the mixed liquid that has passed through the recovery pipe 51B (corresponding to the second or third pipe). That is, the confluence section 50 merges a mixed liquid whose solvent concentration is lower than the concentration reference value with a mixed liquid whose solvent concentration is higher than the concentration reference value. Hereinafter, a mixed liquid with a low solvent concentration that flows into the confluence section 50 will also be referred to as a low-concentration mixed liquid, and a mixed liquid with a high solvent concentration that flows into the confluence section 50 will also be referred to as a high-concentration mixed liquid. Hereinafter, the confluence section 50 generates a mixed liquid whose concentration is higher than the concentration reference value through this merging. Hereinafter, the mixed liquid merged by the confluence section 50 will also be referred to as a merged mixed liquid.

[0083] In the example of FIG. 1, the confluence unit 50 includes a confluence tank Tk2. The low-concentration mixed liquid and the high-concentration mixed liquid are supplied to the confluence tank Tk2. Here, the solvent concentration of the confluence mixed liquid stored in the confluence tank Tk2 is higher than the concentration reference value. In the example of FIG. 1, the confluence unit 50 supplies the confluence mixed liquid to the first dehydrator 60 through a liquid supply pipe 53.

[0084] The first dehydrator 60 includes a first membrane separator 62. The combined mixed liquid from the confluence section 50 flows into the first membrane separator 62. The first membrane separator 62 separates water from the combined mixed liquid, thereby increasing the solvent concentration of the combined mixed liquid.

[0085] As shown in FIG. 1, the first membrane separator 62 includes a first mixing path 62a, a first water path 62b, and a first separation membrane 62c. The combined mixed liquid flows into the first mixing path 62a. The first separation membrane 62c separates the first mixing path 62a from the first water path 62b. The first separation membrane 62c is a membrane that allows the water in the combined mixed liquid to pass through and almost completely blocks the organic solvent. Some of the water in the combined 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. As a result, the solvent concentration of the combined mixed liquid that has passed through the first mixing path 62a becomes higher than the solvent concentration of the combined mixed liquid immediately before flowing into the first mixing path 62a. The first dehydrator 60 uses the first membrane separator 62 to increase the solvent concentration of the combined mixed liquid to a predetermined reuse standard value or higher. The reuse standard value is a solvent concentration that can be used in the processing unit 4, and is set in advance, for example. Hereinafter, the combined mixed liquid whose solvent concentration has been increased to or above the reuse standard value will also be referred to as a reused liquid. It can also be said that the first dehydrator 60 separates water from the combined mixed liquid from the confluence part 50 to generate a reused liquid.

[0086] The upstream end of a liquid supply pipe 85 is connected to the first dehydrator 60, and the downstream end of the 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 liquid supply pipe 85. The mixed liquid in the supply tank Tk3 is supplied to the processing unit 4 again.

[0087] 1, the liquid supply pipe 85 includes a common pipe 850, a first branch pipe 851, and a second branch pipe 852. The upstream end of the common pipe 850 is connected to the first dehydrator 60, and the downstream end of the common pipe 850 is connected to the upstream end of the first branch pipe 851 and the upstream end of the second branch pipe 852. The downstream end of the first branch pipe 851 is connected to the supply tank Tk3 of the substrate processing apparatus 100A, and the downstream end of the second branch pipe 852 is connected to the supply tank Tk3 of the substrate processing apparatus 100B. A liquid supply valve 861 is inserted in the first branch pipe 851, and a liquid supply valve 862 is inserted in the second branch pipe 852.

[0088] When the control unit 6 opens the liquid supply valve 861, the reuse liquid from the first dehydrator 60 can be supplied to the supply tank Tk3 of the substrate processing apparatus 100A. When the control unit 6 opens the liquid supply valve 862, the reuse liquid from the first dehydrator 60 can be supplied to the supply tank Tk3 of the substrate processing apparatus 100B. The reuse liquid in the supply tank Tk3 is supplied to the processing unit 4 again.

[0089] 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.

[0090] 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%.

[0091] Here, the concentration reference value is the lower limit of the concentration of the first separation membrane 62c. In other words, in the first embodiment, since the solvent concentration of the mixed liquid discharged from the substrate processing apparatus 100A is lower than the concentration reference value, treating the mixed liquid in the first dehydrator 60 may cause a malfunction of the first membrane separator 62.

[0092] Therefore, the confluence unit 50, which is provided upstream of the first dehydrator 60, merges the high-concentration mixed liquid discharged from the substrate processing apparatus 100B with the low-concentration mixed liquid from the substrate processing apparatus 100A to generate a combined mixed liquid having a solvent concentration equal to or higher than the reference concentration value. Because the solvent concentration of the combined mixed liquid is equal to or higher than the lower limit concentration value of the first separation membrane 62c, the first dehydrator 60 can appropriately separate water from the combined mixed liquid using the first membrane separator 62. In other words, the first dehydrator 60 can reliably increase the solvent concentration of the combined mixed liquid to generate a reused liquid.

[0093] The first dehydrator 60 separates water from the combined mixed liquid using a first membrane separator 62. Because the energy efficiency of membrane separation is higher than the energy efficiency of other separation methods such as distillation, the first dehydrator 60 can increase the solvent concentration of the combined mixed liquid with higher efficiency.

[0094] As described above, the organic solvent recovery unit 5 can increase the solvent concentration of the mixed liquid with higher reliability and higher efficiency. Furthermore, 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.

[0095] <3-1. Specific example of organic solvent recovery unit 5> The organic solvent recovery unit 5 can be accommodated in a first accommodation box 50a (see FIG. 2). As an example, the first accommodation 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).

[0096] <Confluence 50> 1, the junction section 50 includes a junction pipe 518 and a junction tank Tk2. The upstream end of the junction pipe 518 is connected to the downstream end of the recovery pipe 51A and the downstream end of the recovery pipe 51B, and the downstream end of the junction pipe 518 is connected to the junction tank Tk2.

[0097] 1, a recovery valve 52 is inserted in recovery pipe 51. Specifically, a recovery valve 52A is inserted in recovery pipe 51A, and a recovery valve 52B is inserted in recovery pipe 51B.

[0098] When the control unit 6 opens the recovery valve 52A, the mixed liquid from the substrate processing apparatus 100A is supplied to the junction tank Tk2 through the recovery pipe 51A and the junction pipe 518. When the control unit 6 opens the recovery valve 52B, the mixed liquid from the substrate processing apparatus 100B is supplied to the junction tank Tk2 through the recovery pipe 51B and the junction pipe 518. This causes the junction tank Tk2 to store the junction mixed liquid. Note that, unlike in FIG. 1, the downstream end of the recovery pipe 51A and the downstream end of the recovery pipe 51B may be directly connected to the junction tank Tk2.

[0099] Furthermore, the low-concentration mixed solution from the substrate processing apparatus 100A may be temporarily flowed into a low-concentration buffer tank (not shown), and the high-concentration mixed solution from the substrate processing apparatus 100B may be temporarily flowed into a high-concentration buffer tank (not shown). The low-concentration buffer tank may be inserted into the recovery pipe 51A, for example, upstream of the recovery valve 52A, and the high-concentration buffer tank may be inserted into the recovery pipe 51B, for example, upstream of the recovery valve 52B. In this case, the low-concentration mixed solution from the low-concentration buffer tank and the high-concentration mixed solution from the high-concentration buffer tank flow into the confluence tank Tk2.

[0100] The amount of low-concentration mixed solution supplied to the junction tank Tk2 can be adjusted by a recovery valve 52 A. Similarly, the amount of high-concentration mixed solution supplied to the junction tank Tk2 can be adjusted by a recovery valve 52 B.

[0101] However, it is also possible that the amount of high-concentration mixed liquid discharged from the substrate processing apparatus 100B may be smaller than the amount of low-concentration mixed liquid discharged from the substrate processing apparatus 100A. In this case, there is a risk that the high-concentration mixed liquid will be insufficient to generate a confluent mixed liquid having a solvent concentration equal to or greater than the reference concentration. Therefore, new organic solvent may be supplied to the confluence section 50. FIG. 4 is a schematic diagram showing another example of the confluence section 50. In the example shown in FIG. 4, the downstream end of a new liquid pipe 56 is also connected to the confluence tank Tk2 of the confluence section 50. A new liquid supply source is connected to the upstream end of the new liquid pipe 56. The new liquid supply source is a supply source of unused organic solvent that has never been supplied to a substrate W. The solvent concentration of the new liquid is naturally higher than the reference concentration, e.g., 99.8 wt% or higher. A new liquid valve 57 is inserted into the new liquid pipe 56.

[0102] When the control unit 6 opens the new liquid valve 57, new liquid from the new liquid supply source is supplied to the junction tank Tk2 through the new liquid piping 56. Therefore, the junction unit 50 can merge the low-concentration mixed liquid, the high-concentration mixed liquid, and the new liquid. The amount of new liquid supplied to the junction tank Tk2 is adjusted by, for example, the new liquid valve 57.

[0103] As described above, in the example of Figure 4, the low concentration mixed liquid flows into the confluence tank Tk2 via the recovery pipe 51A (corresponding to the first pipe), the high concentration mixed liquid flows into the recovery pipe 51B (corresponding to the third pipe), and the new liquid flows into the new liquid pipe 56 (corresponding to the second pipe).

[0104] 4, the confluence unit 50 also includes a concentration sensor Sn5. The concentration sensor Sn5 measures the solvent concentration of the confluence mixture in the confluence tank Tk2 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.

[0105] The control unit 6 may control the new liquid valve 57 based on the solvent concentration measured by the concentration sensor Sn5. In other words, when the solvent concentration is low, the control unit 6 may open the new liquid valve. This allows new liquid to be supplied to the junction tank Tk2 through the new liquid piping 56. The solvent concentration of the junction mixture in the junction tank Tk2 increases as the inflow rate of new liquid increases. Therefore, the junction unit 50 can more reliably produce a junction mixture having a solvent concentration equal to or higher than the reference concentration value.

[0106] The supply amounts of the low-concentration mixed liquid, the high-concentration mixed liquid, and the new liquid can be adjusted respectively by the recovery valve 52A, the recovery valve 52B, and the new liquid valve 57. Therefore, the recovery valve 52A, the recovery valve 52B, and the new liquid valve 57 can function as a regulator 59 that adjusts the merging ratio of the low-concentration mixed liquid, the high-concentration mixed liquid, and the new liquid.

[0107] 1 and 4, the upstream end of a liquid supply pipe 53 is connected to, for example, the bottom of the junction tank Tk2. In the example of FIG. 1, a liquid supply valve 54 and a pump 55, which is an example of a liquid supply unit, are inserted in the liquid supply pipe 53. When the control unit 6 opens the liquid supply valve 54 and operates the pump 55, the junction mixed liquid in the junction tank Tk2 is supplied to the first dehydrator 60 through the liquid supply pipe 53.

[0108] <3-1-1. 1st dehydrator> 5 is a diagram schematically illustrating an example of the first dehydrator 60. In the example of FIG.

[0109] (a) Concentration tank Tk1 In the example of Fig. 5, the downstream end of the liquid supply pipe 53 is connected to the concentration tank Tk1. The combined mixed liquid is supplied to the concentration tank Tk1 from the confluence section 50 through the liquid supply pipe 53. The concentration tank Tk1 stores the combined mixed liquid. As described above, the solvent concentration of the combined mixed liquid is equal to or higher than the lower limit concentration of the first separation membrane 62c.

[0110] (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 combined 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 combined 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. 5, 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.

[0111] The first membrane separator 62 is provided in the first circulation pipe 63. Specifically, the first mixing path 62a of the first membrane separator 62 is inserted into the first circulation pipe 63 and constitutes part of the first circulation path of the first circulation unit 61. Therefore, the combined mixed liquid passes through the first mixing path 62a. A portion of the water in the combined 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 combined mixed liquid immediately after the first membrane separator 62 becomes higher in the first circulation pipe 63 than the solvent concentration of the combined mixed liquid immediately before the first membrane separator 62. Because the first circulation unit 61 circulates the combined mixed liquid through the first circulation pipe 63, the combined mixed liquid continues to flow into the first membrane separator 62. Therefore, the first membrane separator 62 continues to separate water from the combined mixed liquid. As a result, the solvent concentration of the circulating combined mixed liquid 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.

[0112] 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.

[0113] 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. 5, a discharge valve 67 is inserted in the separation discharge pipe 66.

[0114] In the example of FIG. 5, 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.

[0115] 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.

[0116] 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.

[0117] <3-1-2.Recycled liquid supply section 89> 5, 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 liquid supply pipe 85, a liquid supply valve 861 (see FIG. 1), a liquid supply valve 862 (see FIG. 1), and a pump 64, which is an example of a liquid supply unit.

[0118] In the example of FIG. 5 , the supply tank Tk3 is connected to the first circulation pipe 63 through the liquid supply pipe 85. That is, the downstream end of the liquid supply pipe 85 is connected to the supply tank Tk3, and the upstream end of the liquid supply pipe 85 is connected to the first circulation pipe 63. Specifically, the upstream end of the liquid supply 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 liquid supply pipe 85 is connected to the first circulation pipe 63 at a position between the pump 64 and the first membrane separator 62. Note that the upstream end of the liquid supply 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 liquid supply pipe 85.

[0119] <3-2. Example of Operation of Organic Solvent Recovery Unit 5> 6 is a flowchart showing an example of the operation of the organic solvent recovery unit 5. First, the confluence unit 50 confluences the low-concentration mixed liquid and the high-concentration mixed liquid to generate a confluence mixed liquid (step S1: confluence process). Specifically, the control unit 6 opens the recovery valves 52A and 52B. As a result, the low-concentration mixed liquid from the substrate processing apparatus 100A and the high-concentration mixed liquid from the substrate processing apparatus 100B are supplied to the confluence tank Tk2. The confluence unit 50 confluences the low-concentration mixed liquid and the high-concentration mixed liquid to generate a confluence mixed liquid having a concentration equal to or greater than the reference value.

[0120] As described above, a shortage of high-concentration mixed liquid may cause the solvent concentration of the combined mixed liquid to fall below the concentration reference value. Therefore, the confluence unit 50 may merge new liquid. First, the concentration sensor Sn5 measures the solvent concentration of the combined mixed liquid in the confluence tank Tk2 and outputs the measurement result to the control unit 6. The control unit 6 then compares the solvent concentration measured by the concentration sensor Sn5 with a first concentration reference value. The first concentration reference value may be the same as or higher than the concentration lower limit (i.e., the concentration reference value) of the first separation membrane 62c. The first concentration reference value is set to a value less than the reuse reference value, for example, closer to the concentration lower limit than the reuse reference value. When the solvent concentration is less than the first concentration reference value, the control unit 6 opens the new liquid valve 57. This allows new liquid with a high solvent concentration to be supplied to the confluence unit 50, and the new liquid is supplied to the confluence tank Tk2. As a result, the solvent concentration of the combined mixed liquid increases. The concentration sensor Sn5 may measure the solvent concentration of the joined mixed liquid at predetermined time intervals, for example. The control unit 6 closes the new liquid valve 57 when the solvent concentration measured by the concentration sensor Sn5 becomes equal to or greater than a first concentration reference value.

[0121] In other words, the control unit 6 controls the new liquid valve 57 so as to supply new liquid to the confluence unit 50 in an amount that makes the solvent concentration of the confluence mixture equal to or greater than the concentration reference value. This allows the organic solvent recovery unit 5 to more reliably store the confluence mixture having a solvent concentration equal to or greater than the concentration reference value in the confluence tank Tk2.

[0122] Then, the confluence unit 50 supplies the confluence mixture to the first dehydrator 60. Specifically, the control unit 6 opens the liquid supply valve 54 and operates the pump 55. As a result, the confluence mixture in the confluence tank Tk2 is supplied to the first dehydrator 60. In the example of FIG. 5, the confluence mixture is supplied to the concentration tank Tk1.

[0123] Next, the first dehydrator 60 separates water from the combined mixed liquid to further increase the solvent concentration of the combined mixed liquid (step S2: dehydration process). Specifically, the first circulation unit 61 circulates the combined 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 combined mixed liquid circulates through the first circulation path including the concentration tank Tk1 and the first circulation piping 63. Due to this circulation, the combined 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 combined 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 circulating combined mixed liquid increases over time.

[0124] The control unit 6 circulates the combined mixed liquid through the first circulation unit 61 until the solvent concentration of the circulating combined mixed liquid 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 cause the first circulation unit 61 to stop circulation when the solvent concentration reaches or exceeds the reuse standard value. 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.

[0125] As a result of this circulation, the concentration tank Tk1 stores the combined mixed liquid (i.e., the reused liquid) with an increased solvent concentration. 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.

[0126] 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 861 or the liquid supply valve 862 and operates the pump 64. As a result, the reuse liquid in the concentration tank Tk1 is supplied to the supply tank Tk3 of the substrate processing apparatus 100A or 100B through at least the liquid supply pipe 85.

[0127] 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.

[0128] In the above example, the first dehydrator 60 repeatedly flows the combined mixed liquid into the first membrane separator 62 by circulating it through the first circulation unit 61, thereby increasing the solvent concentration of the combined 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 combined mixed liquid, the size of the first membrane separator 62 needs to be increased to ensure the increase in solvent concentration. In contrast, in the above specific example, the first dehydrator 60 increases the solvent concentration of the combined 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.

[0129] Although the above example shows that both the confluence tank Tk2 and the concentration tank Tk1 are provided, this is not necessarily limited to this. A low-concentration mixed solution and a high-concentration mixed solution may be supplied to the concentration tank Tk1. Specifically, the downstream end of the confluence pipe 518 may be connected to the concentration tank Tk1. In this case, the concentration tank Tk1 also functions as the confluence tank Tk2.

[0130] In the above example, the low-concentration mixed liquid from the substrate processing apparatus 100A and the high-concentration mixed liquid from the substrate processing apparatus 100B flow into the junction tank Tk2. However, this is not necessarily limited to this. For example, the low-concentration mixed liquid may flow into the junction tank Tk2 via the recovery pipe 51A (corresponding to the first pipe) and the new liquid may flow into the junction tank Tk2 via the new liquid pipe 56 (corresponding to the second pipe). In other words, the recovery pipe 51B does not have to be connected to the junction tank Tk2.

[0131] <Second embodiment> 7 is a diagram schematically illustrating an example of the confluence section 50 according to the second embodiment. The confluence section 50 according to the second embodiment includes a first confluence tank Tk21, a second confluence tank Tk22, a recovery destination switching section 500, and a supply source switching section 550.

[0132] The recovery destination switching unit 500 switches the recovery destination of the low concentration mixed liquid from the substrate processing apparatus 100A and the high concentration mixed liquid from the substrate processing apparatus 100B between the first junction tank Tk21 and the second junction tank Tk22.

[0133] 7, recovery destination switching unit 500 includes recovery piping 51 and a switching valve unit 520. In Fig. 7, recovery piping 51A is shown as recovery piping 51 for substrate processing apparatus 100A, and switching valve unit 520A is shown as switching valve unit 520 for substrate processing apparatus 100A. Also, recovery piping 51B is shown as recovery piping 51 for substrate processing apparatus 100B, and switching valve unit 520B is shown as switching valve unit 520 for substrate processing apparatus 100B.

[0134] The recovery pipe 51A includes a common recovery pipe 510A, a first branch pipe 511A, and a second branch pipe 512A. The common recovery pipe 510A is connected to the substrate processing apparatus 100A. Specifically, the downstream ends of the cup-side recovery pipes 424 of the substrate processing apparatus 100A are connected to the common recovery pipe 510A. Therefore, the low-concentration mixed solution flows into the common recovery pipe 510A. The downstream end of the common recovery pipe 510A is connected to the upstream end of the first branch pipe 511A and the upstream end of the second branch pipe 512A. The downstream end of the first branch pipe 511A is connected to a first junction tank Tk21, and the downstream end of the second branch pipe 512A is connected to a second junction tank Tk22.

[0135] 7, the switching valve unit 520A includes a switching valve 521A and a switching valve 522A. The switching valve unit 520A switches between a state in which the common recovery pipe 510A is connected to the first junction tank Tk21 via the first branch pipe 511A and a state in which the common recovery pipe 510A is connected to the second junction tank Tk22 via the second branch pipe 512A. In the example of FIG. 7, the switching valve 521A is inserted in the first branch pipe 511A, and the switching valve 522A is inserted in the second branch pipe 512A.

[0136] When the control unit 6 opens the switching valve 521A, the low concentration mixed solution from the substrate processing apparatus 100A is supplied to the first junction tank Tk21. On the other hand, when the control unit 6 opens the switching valve 522A, the low concentration mixed solution from the substrate processing apparatus 100A is supplied to the second junction tank Tk22.

[0137] The recovery pipe 51B and the switching valve section 520B are similar to the recovery pipe 51A and the switching valve section 520A, respectively. For example, the recovery pipe 51B includes a common recovery pipe 510B, a first branch pipe 511B, and a second branch pipe 512B, which are similar to the common recovery pipe 510A, the first branch pipe 511A, and the second branch pipe 512A, respectively. However, the common recovery pipe 510B is connected to the substrate processing apparatus 100B. In the example of FIG. 7, the switching valve section 520B includes a switching valve 521B and a switching valve 522B, which are similar to the switching valve 521A and the switching valve 522A, respectively.

[0138] When the control unit 6 opens the switching valve 521B, the high concentration mixed solution from the substrate processing apparatus 100B is supplied to the first junction tank Tk21. On the other hand, when the control unit 6 opens the switching valve 522B, the high concentration mixed solution from the substrate processing apparatus 100B is supplied to the second junction tank Tk22.

[0139] In the example of FIG. 7, a new liquid switching unit 580 that switches the supply destination of new liquid between a first junction tank Tk21 and a second junction tank Tk22 is provided in the junction unit 50. The new liquid switching unit 580 includes a new liquid pipe 56 and a switching valve unit 570. The new liquid pipe 56 includes a common new liquid pipe 560, a first branch pipe 561, and a second branch pipe 562. The upstream end of the common new liquid pipe 560 is connected to a new liquid supply source. The downstream end of the common new liquid pipe 560 is connected to the upstream end of the first branch pipe 561 and the upstream end of the second branch pipe 562, the downstream end of the first branch pipe 561 is connected to the first junction tank Tk21, and the downstream end of the second branch pipe 562 is connected to the second junction tank Tk22.

[0140] 7, the switching valve unit 570 includes a switching valve 571 and a switching valve 572. The switching valve unit 570 switches between a state in which the common new liquid pipe 560 is connected to the first junction tank Tk21 through the first branch pipe 561 and a state in which the common new liquid pipe 560 is connected to the second junction tank Tk22 through the second branch pipe 562. In the example of FIG. 7, the switching valve 571 is inserted in the first branch pipe 561, and the switching valve 572 is inserted in the second branch pipe 562.

[0141] When the control unit 6 opens the switching valve 571, new liquid is supplied to the first junction tank Tk21. On the other hand, when the control unit 6 opens the switching valve 572, new liquid is supplied to the second junction tank Tk22.

[0142] In the example of FIG. 7, the organic solvent recovery unit 5 includes a first measurement circulation unit 81 and a second measurement circulation unit 82. The first measurement circulation unit 81 measures the solvent concentration of the merged mixed solution in the first junction tank Tk21. In the example of FIG. 7, the first measurement circulation unit 81 includes a first measurement circulation pipe 811, a switching valve 821, a pump 831, and a concentration sensor Sn51. The first measurement circulation pipe 811 is a pipe that returns the mixed solution from the first junction tank Tk21 to the first junction tank Tk21. In other words, the mixed solution circulates through a first measurement circulation path that includes the first junction tank Tk21 and the first measurement circulation pipe 811. In the example of FIG. 7, the upstream end of the first measurement circulation pipe 811 is connected to the bottom of the first junction tank Tk21, and the downstream end of the first measurement circulation pipe 811 is connected to the top of the first junction tank Tk21. The switching valve 821 and the pump 831 are interposed in the first measurement circulation pipe 811. The switching valve 821 is provided downstream of the pump 831. The concentration sensor Sn51 measures the solvent concentration of the mixed liquid flowing through the first measurement circulation pipe 811. An example of the configuration of the concentration sensor Sn51 is similar to that of the concentration sensor Sn5.

[0143] The concentration sensor Sn51 measures the solvent concentration of the confluent mixed liquid while the first measurement circulation unit 81 circulates the confluent mixed liquid through the first measurement circulation path. This measurement value can be said to indicate the solvent concentration of the confluent mixed liquid in the first confluence tank Tk21.

[0144] The second measurement circulation unit 82 measures the solvent concentration of the converged mixed solution in the second confluence tank Tk22. An example of the configuration of the second measurement circulation unit 82 is similar to that of the first measurement circulation unit 81. That is, the second measurement circulation unit 82 includes a second measurement circulation pipe 812, a switching valve 822, a pump 832, and a concentration sensor Sn52, which are similar to the first measurement circulation pipe 811, the switching valve 821, the pump 831, and the concentration sensor Sn51, respectively. However, the second measurement circulation pipe 812 is connected to the second confluence tank Tk22.

[0145] The supply source switching unit 550 switches the supply source that supplies the combined mixed liquid to the first dehydrator 60 between the first junction tank Tk21 and the second junction tank Tk22. In the example of FIG. 7, the supply source switching unit 550 includes a liquid supply pipe 53 and a switching valve unit 540. The liquid supply pipe 53 includes a common liquid supply pipe 530, a first branch pipe 531, and a second branch pipe 532. The downstream end of the common liquid supply pipe 530 is connected to the first dehydrator 60. The upstream end of the common liquid supply pipe 530 is connected to the downstream end of the first branch pipe 531 and the downstream end of the second branch pipe 532. In the example of FIG. 7, the upstream end of the first branch pipe 531 is connected to the first measurement circulation pipe 811 between the switching valve 821 and the pump 831, and the upstream end of the second branch pipe 532 is connected to the second measurement circulation pipe 812 between the switching valve 822 and the pump 832.

[0146] The upstream end of the first branch pipe 531 may be connected to the first junction tank Tk21, and the upstream end of the second branch pipe 532 may be connected to the second junction tank Tk22. In this case, a pump (not shown) is inserted in each of the first branch pipe 531 and the second branch pipe 532.

[0147] 7, the switching valve unit 540 includes a liquid supply valve 541 and a liquid supply valve 542. The switching valve unit 540 switches between a state in which the first junction tank Tk21 is connected to the first dehydrator 60 and a state in which the second junction tank Tk22 is connected to the first dehydrator 60. In the example of FIG. 7, the liquid supply valve 541 is inserted in the first branch pipe 531, and the liquid supply valve 542 is inserted in the second branch pipe 532.

[0148] When the control unit 6 opens the liquid supply valve 541 and operates the pump 831, the combined mixed liquid from the first junction tank Tk21 is supplied to the first dehydrator 60. On the other hand, when the control unit 6 opens the liquid supply valve 542 and operates the pump 832, the combined mixed liquid from the second junction tank Tk22 is supplied to the first dehydrator 60.

[0149] 8 is a diagram illustrating an example of the operation of the organic solvent recovery unit 5 according to the second embodiment. First, the recovery destination switching unit 500 selects the first junction tank Tk21 as the recovery destination of the mixed liquid. Specifically, the control unit 6 opens the switching valves 521A and 521B. As a result, the low-concentration mixed liquid from the substrate processing apparatus 100A and the high-concentration mixed liquid from the substrate processing apparatus 100B are supplied to the first junction tank Tk21. In other words, the low-concentration mixed liquid and the high-concentration mixed liquid are recovered in the first junction tank Tk21. Therefore, the amount of the mixed liquid stored in the first junction tank Tk21 increases over time.

[0150] For example, when the amount of the mixed liquid stored in the first confluence tank Tk21 exceeds a predetermined storage reference value, the control unit 6 causes the recovery destination switching unit 500 to switch the recovery destination. The stored amount may be measured, for example, by a sensor (e.g., a liquid level sensor) (not shown) and output to the control unit 6. For example, when the stored amount measured by the sensor exceeds the storage reference value, the control unit 6 closes the switching valves 521A and 521B and opens the switching valves 522A and 522B. As a result, the low-concentration mixed liquid from the substrate processing apparatus 100A and the high-concentration mixed liquid from the substrate processing apparatus 100B are collected in the second confluence tank Tk22. Therefore, the amount of the mixed liquid stored in the second confluence tank Tk22 increases over time.

[0151] While the second junction tank Tk22 is recovering the mixed liquid, the control unit 6 checks the solvent concentration of the mixed liquid in the first junction tank Tk21. Specifically, first, the control unit 6 opens the switching valve 821 and operates the pump 831. This causes the mixed liquid to circulate through the first measurement circulation path. The concentration sensor Sn51 then measures the solvent concentration of the circulating mixed liquid and outputs the measurement result to the control unit 6. The control unit 6 compares the measured solvent concentration with a first concentration reference value. If the solvent concentration is equal to or greater than the first concentration reference value, the control unit 6 closes the switching valve 821 and opens the liquid supply valve 541 to supply the mixed liquid in the first junction tank Tk21 to the first dehydrator 60.

[0152] On the other hand, when the solvent concentration is less than the concentration reference value, the control unit 6 opens the switching valve 571 to supply new liquid to the first junction tank Tk21. This increases the solvent concentration of the junction mixture in the first junction tank Tk21. Then, when the solvent concentration measured by the concentration sensor Sn51 becomes equal to or greater than the first concentration reference value, the control unit 6 closes the switching valve 571. Next, the control unit 6 closes the switching valve 821 and opens the liquid supply valve 541 to supply the junction mixture in the first junction tank Tk21 to the first dehydrator 60. As a result, the amount of junction mixture stored in the first junction tank Tk21 decreases over time, for example, to approximately zero.

[0153] Thereafter, when the amount of the mixed solution stored in the second confluence tank Tk22 reaches or exceeds the storage reference value, the control unit 6 causes the recovery destination switching unit 500 to switch the recovery destination, so that the low-concentration mixed solution and the high-concentration mixed solution are again recovered into the first confluence tank Tk21.

[0154] While the mixed solution is being recovered by the first confluence tank Tk21, the control unit 6 checks the solvent concentration of the mixed solution in the second confluence tank Tk22 by operating the second measurement / circulation unit 82. The operation of the second measurement / circulation unit 82 is the same as that of the first measurement / circulation unit 81. Then, the organic solvent recovery unit 5 opens the switching valve 572 to supply new solution to the second confluence tank Tk22 as necessary, and then opens the liquid supply valve 542 to supply the combined mixed solution in the second confluence tank Tk22 to the first dehydrator 60. This causes the second confluence tank Tk22 to become, for example, almost empty. The operation of the switching valve 572 and the liquid supply valve 542 are the same as those of the switching valve 571 and the liquid supply valve 541, respectively.

[0155] As described above, in the second embodiment, while one of the first confluence tank Tk21 and the second confluence tank Tk22 is recovering a mixed liquid, the solvent concentration of the mixed liquid in the other confluence tank is adjusted as necessary, and the mixed liquid is then supplied from the other confluence tank to the first dehydrator 60. Therefore, neither the low-concentration mixed liquid nor the high-concentration mixed liquid is supplied to the confluence tank whose solvent concentration is being adjusted. This allows for more reliable adjustment of the solvent concentration.

[0156] Furthermore, the recovery destination of the mixed solution is alternately switched between the first junction tank Tk21 and the second junction tank Tk22. Therefore, the organic solvent recovery unit 5 can always recover the low-concentration mixed solution and the high-concentration mixed solution from the junction tank where the concentration adjustment is not performed.

[0157] In the above example, when the solvent concentration of the combined mixed solution in the first junction tank Tk21 is measured, the combined mixed solution circulates through the first measurement circulation path. This causes the combined mixed solution in the first junction tank Tk21 to be agitated, making the concentration distribution of the mixed solution more uniform. The same applies to the second junction tank Tk22. The first measurement circulation unit 81 and the second measurement circulation unit 82 can also be considered agitation circulation units. This agitation allows the junction unit 50 to supply a mixed solution with a more uniform concentration distribution to the first dehydrator 60. If the concentration distribution of the mixed solution varies, a mixed solution with a low solvent concentration may instantaneously flow into the first separation membrane 62c. In the above example, the junction unit 50 can more uniformly distribute the concentration, thereby reducing the possibility of a mixed solution with a low solvent concentration instantaneously flowing into the first separation membrane 62c.

[0158] <Third embodiment> In the first and second embodiments, a case has been described in which a low-concentration mixed liquid is discharged from the substrate processing apparatus 100A and a high-concentration mixed liquid is discharged from the substrate processing apparatus 100B. However, since the solvent concentration of the mixed liquid depends on the processing content of each processing unit 4, it is also possible that a high-concentration mixed liquid and a low-concentration mixed liquid are discharged from the same substrate processing apparatus 100. The third embodiment aims to provide an organic solvent recovery unit 5 that can handle such cases.

[0159] FIG. 9 is a schematic diagram illustrating an example of an organic solvent recovery unit 5 according to a third embodiment. As shown in FIG. 9, the organic solvent recovery unit 5 according to the third embodiment includes a low-concentration tank Tk2L and a high-concentration tank Tk2H. The low-concentration tank Tk2L stores a mixed liquid having a solvent concentration below a reference concentration value. The high-concentration tank Tk2H stores a mixed liquid having a solvent concentration equal to or greater than the reference concentration value. In the third embodiment, the organic solvent recovery unit 5 switches the destination of the mixed liquid from the substrate processing apparatus 100 between the low-concentration tank Tk2L and the high-concentration tank Tk2H depending on the solvent concentration. The organic solvent recovery unit 5 then merges the low-concentration mixed liquid from the low-concentration tank Tk2L and the high-concentration mixed liquid from the high-concentration tank Tk2H to generate a merged mixed liquid having a solvent concentration equal to or greater than the reference concentration value.

[0160] 9, the organic solvent recovery unit 5 includes a first recovery destination switching unit 500A and a second recovery destination switching unit 500B. The first recovery destination switching unit 500A switches the recovery destination of the mixed solution from the substrate processing apparatus 100A between the low-concentration tank Tk2L and the high-concentration tank Tk2H. That is, the first recovery destination switching unit 500A switches between a first low-concentration state in which the substrate processing apparatus 100A is connected to the low-concentration tank Tk2L and a first high-concentration state in which the substrate processing apparatus 100A is connected to the high-concentration tank Tk2H. The first recovery destination switching unit 500A includes a recovery pipe 51A and a switching valve unit 520A, as in the second embodiment. However, the downstream end of a first branch pipe 511A of the recovery pipe 51A is connected to the low-concentration tank Tk2L, and the downstream end of a second branch pipe 512A of the recovery pipe 51A is connected to the high-concentration tank Tk2H.

[0161] The control unit 6 controls the first recovery destination switching unit 500A according to the solvent concentration of the mixed solution from the substrate processing apparatus 100A. In the example of FIG. 9, a concentration sensor Sn5A is provided in the common recovery pipe 510A. The concentration sensor Sn5A measures the solvent concentration of the mixed solution flowing through the common recovery pipe 510A and outputs the measurement result to the control unit 6. An example of the configuration of the concentration sensor Sn5A is the same as that of the concentration sensor Sn5. When the solvent concentration of the mixed solution measured by the concentration sensor Sn5A is, for example, less than a concentration reference value, the control unit 6 causes the first recovery destination switching unit 500A to select the first low-concentration state. Specifically, the control unit 6 opens the switching valve 521A and closes the switching valve 522A. As a result, the mixed solution from the substrate processing apparatus 100A is recovered into the low-concentration tank Tk2L.

[0162] On the other hand, when the solvent concentration of the mixed solution measured by the concentration sensor Sn5A is equal to or greater than the concentration reference value, the control unit 6 controls the first recovery destination switching unit 500A to select the first high concentration state. Specifically, the control unit 6 closes the switching valve 521A and opens the switching valve 522A. As a result, the mixed solution from the substrate processing apparatus 100A is recovered into the high concentration tank Tk2H.

[0163] The concentration sensor Sn5A may measure the solvent concentration of the mixed liquid, for example, every time a predetermined time has elapsed, and output the measurement result to the control unit 6. The control unit 6 controls the first recovery destination switching unit 500A based on the solvent concentration, as described above. In this case, the first recovery destination switching unit 500A can switch the recovery destination in accordance with the solvent concentration of the mixed liquid, which varies over time. That is, during a period when a mixed liquid with a low solvent concentration is discharged from the substrate processing apparatus 100A, the mixed liquid is recovered in the low-concentration tank Tk2L, and during a period when a mixed liquid with a high solvent concentration is discharged from the substrate processing apparatus 100A, the mixed liquid is recovered in the high-concentration tank Tk2H.

[0164] The second destination switching unit 500B switches the destination of the mixed solution from the substrate processing apparatus 100B between the low-concentration tank Tk2L and the high-concentration tank Tk2H. That is, the second destination switching unit 500B switches between a second low-concentration state in which the substrate processing apparatus 100B is connected to the low-concentration tank Tk2L and a second high-concentration state in which the substrate processing apparatus 100B is connected to the high-concentration tank Tk2H. The second destination switching unit 500B includes a recovery pipe 51B and a switching valve unit 520B, as in the second embodiment. However, the downstream end of a first branch pipe 511B of the recovery pipe 51B is connected to the low-concentration tank Tk2L, and the downstream end of a second branch pipe 512B of the recovery pipe 51B is connected to the high-concentration tank Tk2H.

[0165] The control unit 6 controls the second recovery destination switching unit 500B in accordance with the solvent concentration of the mixed liquid from the substrate processing apparatus 100B. In the example of Fig. 9, a concentration sensor Sn5B is provided in the common recovery pipe 510B. An example of the configuration of the concentration sensor Sn5B is the same as that of the concentration sensor Sn5. As with the first recovery destination switching unit 500A, the control unit 6 controls the second recovery destination switching unit 500B based on the solvent concentration measured by the concentration sensor Sn5B.

[0166] 9, the organic solvent recovery unit 5 includes a first measurement circulation unit 81 and a second measurement circulation unit 82, similar to the second embodiment. However, the first measurement circulation unit 81 measures the solvent concentration of the low-concentration mixed solution in the low-concentration tank Tk2L, and the second measurement circulation unit 82 measures the solvent concentration of the high-concentration mixed solution in the high-concentration tank Tk2H.

[0167] The control unit 6 determines the confluence ratio of the low-concentration mixed solution and the high-concentration mixed solution based on the solvent concentration of the low-concentration mixed solution in the low-concentration tank Tk2L and the solvent concentration of the high-concentration mixed solution in the high-concentration tank Tk2H. Specifically, the control unit 6 determines the confluence ratio so that the solvent concentration of the confluence mixed solution is equal to or greater than the reference concentration value. The control unit 6 may determine the supply amounts of the low-concentration mixed solution and the high-concentration mixed solution to the confluence unit 50 based on the confluence ratio. For example, the total amount of the mixed solution to be supplied to the confluence unit 50 is set in advance, and the control unit 6 determines the supply amounts based on the total amount and the confluence ratio.

[0168] The organic solvent recovery unit 5 also includes an adjuster 90. The adjuster 90 adjusts the confluence ratio of the low-concentration mixed liquid supplied from the low-concentration tank Tk2L to the confluence unit 50 and the high-concentration mixed liquid supplied from the high-concentration tank Tk2H to the confluence unit 50. In the example of FIG. 9, the adjuster 90 includes a liquid feed pipe 51L (corresponding to the first pipe), a liquid feed pipe 51H (corresponding to the second pipe), an adjustment valve 52L, an adjustment valve 52H, a pump 831, and a pump 832.

[0169] Liquid supply pipe 51L connects low-concentration tank Tk2L and confluence 50 (specifically, confluence tank Tk2), and liquid supply pipe 51H connects high-concentration tank Tk2H and confluence 50 (specifically, confluence tank Tk2). Adjusting valve 52L is inserted in liquid supply pipe 51L, and adjusting valve 52H is inserted in liquid supply pipe 51H.

[0170] When the control unit 6 opens the adjustment valve 52L and operates the pump 831, the low-concentration mixed solution is supplied from the low-concentration tank Tk2L to the junction tank Tk2 through the liquid supply pipe 51L. The supply amount of the low-concentration mixed solution supplied to the junction tank Tk2 is adjusted by the timing of closing the adjustment valve 52L or the timing of stopping the pump 831. When the control unit 6 opens the adjustment valve 52H and operates the pump 832, the high-concentration mixed solution is supplied from the high-concentration tank Tk2H to the junction tank Tk2 through the liquid supply pipe 51H. The supply amount of the high-concentration mixed solution supplied to the junction tank Tk2 is adjusted by the timing of closing the adjustment valve 52H or the timing of stopping the pump 832.

[0171] The upstream end of liquid supply pipe 51L may be connected to low-concentration tank Tk2L, and the upstream end of liquid supply pipe 51H may be connected to high-concentration tank Tk2H. In this case, a pump (not shown) is inserted in each of liquid supply pipe 51L and liquid supply pipe 51H.

[0172] However, in order to maintain the solvent concentration of the confluent mixed liquid at or above the concentration reference value, the amount of high-concentration mixed liquid stored in the high-concentration tank Tk2H may be insufficient. Therefore, in the example of Figure 9, a new liquid pipe 56 is also provided. As shown in Figure 9, the downstream end of the new liquid pipe 56 is connected to the confluent tank Tk2. A new liquid valve 57 is inserted into the new liquid pipe 56.

[0173] In this case, the adjuster 90 adjusts the confluence ratio of the low-concentration mixed liquid passing through the liquid feed pipe 51L, the high-concentration mixed liquid passing through the liquid feed pipe 51H, and the new liquid passing through the new liquid pipe 56. The adjuster 90 includes, for example, an adjustment valve 52L, an adjustment valve 52H, and a new liquid valve 57.

[0174] Fig. 10 is a flowchart showing an example of the operation of the organic solvent recovery unit 5 according to the third embodiment. Fig. 10 mainly shows an example of the operation of each of the first recovery destination switching unit 500A and the second recovery destination switching unit 500B. Below, the operation of the first recovery destination switching unit 500A will be described as a representative example.

[0175] The series of processes in Fig. 10 is repeatedly executed, for example, at predetermined time intervals. As shown in Fig. 10, first, the concentration sensor Sn5A measures the solvent concentration of the mixed liquid flowing through the common recovery pipe 510A (step S11: concentration acquisition step).

[0176] Next, the control unit 6 determines whether the solvent concentration measured by the concentration sensor Sn5A is equal to or greater than the concentration reference value (step S12: concentration determination step). If the solvent concentration is equal to or greater than the concentration reference value, the control unit 6 causes the first recovery destination switching unit 500A to select the high-concentration tank Tk2H as the recovery destination (step S13: high-concentration tank step). Specifically, the control unit 6 opens the switching valve 522A while keeping the switching valve 521A closed. This allows the high-concentration mixed solution to be recovered in the high-concentration tank Tk2H.

[0177] On the other hand, if the solvent concentration is less than the concentration reference value in step S12, the control unit 6 causes the first recovery destination switching unit 500A to select the low-concentration tank Tk2L as the recovery destination (step S14: low-concentration tank step). Specifically, the control unit 6 opens the switching valve 521A and closes the switching valve 522A. As a result, the low-concentration mixed solution is recovered in the low-concentration tank Tk2L.

[0178] 11 is a flowchart showing an example of the operation of the organic solvent recovery unit 5 according to the third embodiment.

[0179] First, the concentration sensor Sn51 measures the solvent concentration of the low-concentration mixed solution in the low-concentration tank Tk2L (step S21: low-concentration acquisition process). Specifically, first, the control unit 6 opens the switching valve 821 and operates the pump 831. This causes the low-concentration mixed solution to circulate through the first measurement circulation path. The concentration sensor Sn51 measures the solvent concentration of the circulating low-concentration mixed solution and outputs the measurement result to the control unit 6. When the measurement is completed, the control unit 6 closes the switching valve 821 and stops the pump 831.

[0180] Next, the concentration sensor Sn5B measures the solvent concentration of the high-concentration mixed solution in the high-concentration tank Tk2H (step S22: high-concentration acquisition step). Specifically, first, the control unit 6 opens the switching valve 822 and operates the pump 832. This causes the high-concentration mixed solution to circulate through the second measurement circulation path. The concentration sensor Sn52 measures the solvent concentration of the circulating high-concentration mixed solution and outputs the measurement result to the control unit 6. When the measurement is completed, the control unit 6 closes the switching valve 822 and stops the pump 832. Note that step S22 may be performed in parallel with step S21, or may be performed before step S21.

[0181] Next, the control unit 6 determines the supply amounts of the low-concentration mixed liquid and the high-concentration mixed liquid to the confluence unit 50 based on the solvent concentrations of the low-concentration mixed liquid and the high-concentration mixed liquid (step S23: supply amount determination step). Specifically, the control unit 6 determines each supply amount so that the solvent concentration of the confluence mixed liquid is equal to or greater than the concentration reference value. As an example, the total supply amount (target value) of the low-concentration mixed liquid and the high-concentration mixed liquid and the solvent concentration (target value) of the confluence mixed liquid are set in advance, and the control unit 6 calculates each supply amount so that the total supply amount and the solvent concentration of the confluence mixed liquid become the target values.

[0182] If at least one of the amount of low-concentration mixed liquid stored in the low-concentration tank Tk2L and the amount of high-concentration mixed liquid stored in the high-concentration tank Tk2H is insufficient, the control unit 6 may determine the amount of shortfall as the amount of new liquid to be supplied.

[0183] Next, the adjuster 90 supplies the low-concentration mixed solution and the high-concentration mixed solution to the confluence section 50 at the calculated supply rates (step S24: confluence process). If the supply rates of the new solution have been determined in step S23, the adjuster 90 supplies the low-concentration mixed solution, the high-concentration mixed solution, and the new solution to the confluence section 50 at the calculated supply rates. As an example, the control unit 6 opens the adjustment valves 52L and 52H and operates the pumps 831 and 832. Based on the respective supply rates, the control unit 6 controls the closing timing of the adjustment valves 52L and 52H and the stopping timing of the pumps 831 and 832. Furthermore, as necessary, the control unit 6 controls the new solution valve 57 to supply the new solution to the confluence tank Tk2. The control unit 6 adjusts the closing timing of the new solution valve 57 based on the calculated supply rate of the new solution. This more reliably stores the confluence mixed solution having a concentration equal to or greater than the reference value in the confluence tank Tk2.

[0184] As described above, in the third embodiment, the mixed solution from substrate processing apparatus 100A and substrate processing apparatus 100B is distributed to low-concentration tank Tk2L and high-concentration tank Tk2H depending on the solvent concentration of the mixed solution. Then, organic solvent recovery unit 5 supplies the mixed solution from low-concentration tank Tk2L and high-concentration tank Tk2H, and also new solution as needed, to confluence unit 50 at supply rates that will make the solvent concentration of the combined mixed solution equal to or greater than the concentration reference value. This allows confluence unit 50 to more reliably make the solvent concentration of the combined mixed solution equal to or greater than the concentration reference value.

[0185] Furthermore, in the above example, multiple substrate processing apparatuses 100 are connected to the organic solvent recovery unit 5. Therefore, the amounts of the mixed liquid recovered in the low-concentration tank Tk2L and the high-concentration tank Tk2H are large. This makes it possible to prevent a shortage of the mixed liquid.

[0186] A single substrate processing apparatus 100 may be connected to the organic solvent recovery unit 5. Even in this case, the mixed liquid from the substrate processing apparatus 100 is distributed to the low-concentration tank Tk2L and the high-concentration tank Tk2H according to the solvent concentration. The organic solvent recovery unit 5 supplies the low-concentration mixed liquid, the high-concentration mixed liquid, and new liquid as needed to the confluence unit 50 at respective supply rates, thereby generating a combined mixed liquid having a concentration equal to or higher than the reference value.

[0187] <Fourth embodiment> FIG. 12 is a schematic diagram illustrating an example of a substrate processing system 1000 according to a fourth embodiment. In the example of FIG. 12, an organic solvent recovery unit 5 is connected to a single substrate processing apparatus 1. In this case, one processing unit 4 of the substrate processing apparatus 1 corresponds to the first processing unit, and the other processing unit 4 corresponds to the second processing unit. The organic solvent recovery unit 5 according to the fourth embodiment differs from the organic solvent recovery unit 5 according to the third embodiment in that it includes a recovery destination switching unit 500. In the fourth embodiment, a switching valve unit 520 of the recovery destination switching unit 500 is provided for each processing unit 4. In the example of FIG. 12, the recovery pipe 51 includes a low-concentration pipe 511, a high-concentration pipe 512, and multiple cup-side recovery pipes 424. The upstream end of each cup-side recovery pipe 424 is connected to a corresponding processing unit 4.

[0188] The downstream end of the low-concentration pipe 511 is connected to the low-concentration tank Tk2L. The low-concentration pipe 511 is also connected to the downstream end of each cup-side recovery pipe 424. In the example of FIG. 12 , the low-concentration pipe 511 includes a first common pipe 513 and a plurality of first branch pipes 514. The plurality of first branch pipes 514 are provided in a one-to-one correspondence with the plurality of cup-side recovery pipes 424. The upstream end of the first branch pipe 514 is connected to the downstream end of the corresponding cup-side recovery pipe 424, and the downstream end of the first branch pipe 514 is connected to the first common pipe 513. The downstream end of the first common pipe 513 corresponds to the downstream end of the low-concentration pipe 511.

[0189] The downstream end of the high-concentration pipe 512 is connected to the high-concentration tank Tk2H. The high-concentration pipe 512 is also connected to the downstream end of each cup-side recovery pipe 424. In the example of FIG. 12 , the high-concentration pipe 512 includes a second common pipe 515 and a plurality of second branch pipes 516. The plurality of second branch pipes 516 are provided in a one-to-one correspondence with the plurality of cup-side recovery pipes 424. The upstream end of the second branch pipe 516 is connected to the downstream end of the corresponding common recovery pipe 510, and the downstream end of the second branch pipe 516 is connected to the second common pipe 515. The downstream end of the second common pipe 515 corresponds to the downstream end of the high-concentration pipe 512.

[0190] 12, switching valve section 520 includes switching valve 521 and switching valve 522. Switching valve section 520 switches between a state in which cup-side recovery pipe 424 is connected to low-concentration tank Tk2L and a state in which cup-side recovery pipe 424 is connected to high-concentration tank Tk2H. In the example of FIG. 12, multiple switching valve sections 520 are provided in a one-to-one relationship with multiple processing units 4. That is, in the example of FIG. 12, multiple switching valves 521 are provided in a one-to-one relationship with multiple processing units 4, and multiple switching valves 522 are provided in a one-to-one relationship with multiple 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.

[0191] The following describes the operation of switching valve section 520 corresponding to one processing unit 4. When control section 6 closes switching valve 521 and opens switching valve 522, the mixed liquid from processing unit 4 flows through cup-side recovery pipe 424 and high-concentration piping 512 in this order, and is supplied to high-concentration tank Tk2H. When control section 6 opens switching valve 521 and closes switching valve 522, the mixed liquid from processing unit 4 flows through cup-side recovery pipe 424 and low-concentration piping 511 in this order, and is supplied to low-concentration tank Tk2L.

[0192] The control unit 6 controls the recovery destination switching unit 500 based on the solvent concentration of the mixed solution discharged from the processing unit 4. Specifically, the control unit 6 causes the recovery destination switching unit 500 to select the low-concentration tank Tk2L as the recovery destination when the solvent concentration of the mixed solution is equal to or greater than the concentration reference value, and causes the recovery destination switching unit 500 to select the high-concentration tank Tk2H as the recovery destination when the solvent concentration of the mixed solution is less than the concentration lower limit value.

[0193] An example of the operation of the recovery destination switching unit 500 is the same as that shown in Fig. 10. However, in the fourth embodiment, the control unit 6 may calculate the solvent concentration of the mixed solution from the processing unit 4 in step S11 based on the processing content of the processing unit 4, as will be described later.

[0194] <Calculation of solvent concentration based on recipe information> Here, 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.

[0195] 13 is a diagram schematically illustrating an example of a processing unit 4 according to the fourth embodiment. As shown in FIG. 13, 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.

[0196] 13, the processing unit 4 may include a plurality of cups 42. In the example of FIG. 13, 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. 13, 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.

[0197] 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.

[0198] 13, 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).

[0199] 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.

[0200] 13, 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.

[0201] [Table 1]

[0202] 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.

[0203] Fig. 14 is a diagram schematically illustrating an example of the state of the processing unit 4 in each step in Table 1. Fig. 14(a) to Fig. 14(f) illustrate an example of the state of the processing unit 4 in the 30th step to the 35th step in Table 1, respectively.

[0204] 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. 14(a), in the 30th step, pure water splashed from the periphery of the substrate W is received by the cup 42A.

[0205] 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. 14(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.

[0206] 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. 14(c)).

[0207] 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. 14(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.

[0208] 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. 14(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 the 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.

[0209] 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. 14(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.

[0210] As described above, the cup 42C is raised to the upper position in the 31st step (see also FIG. 14(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.

[0211] 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.

[0212] 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. 14(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.

[0213] FIG. 15 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. 15 shows multiple graphs G1 to G4 representing 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.

[0214] 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. 13). 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.

[0215] 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.

[0216] 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.

[0217] Table 2 is a table that schematically shows a second example of the recipe information D1.

[0218] [Table 2]

[0219] Table 2 also shows some of the steps in the processing performed on the substrate W. Fig. 16 is a diagram schematically showing an example of the state of the processing unit 4 in each step in Table 2. Fig. 16(a) to Fig. 16(e) show an example of the state of the processing unit 4 in the 30th step to the 34th step in Table 2, respectively.

[0220] 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. 16(a), in the 30th step, pure water splashed from the periphery of the substrate W is received by the cup 42A.

[0221] In the 31st step, the spin chuck 41 rotates the substrate W at 1500 rpm for two seconds, while the rinse liquid nozzle 43b discharges 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. 16(b)). As a result, the pure water is received by cup 42C and flows into the upstream end of the recovery pipe 51.

[0222] 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. 16(c), in the 32nd step as well, the processing liquid splashed from the periphery of the substrate W is received in the cup 42C.

[0223] In step 33, the spin chuck 41 rotates the substrate W at 1500 rpm for 30 seconds, while the IPA nozzle 43c discharges the organic solvent at 250 mL / min toward the main surface of the substrate W. As shown in Fig. 16(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.

[0224] 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. 16(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.

[0225] 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.

[0226] 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.

[0227] As described above, the amount of pure water film depends on the rotation speed of the substrate W. Fig. 17 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. 17. 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.

[0228] 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.

[0229] 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.

[0230] 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.

[0231] 18 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 S31: reading step).

[0232] Next, the concentration estimation unit 601 calculates the amount of pure water film based on the recipe information D1 (step S32: 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. 14(c) or FIG. 16(b)) based on the identified rotation speed and the correspondence relationship information D2.

[0233] 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.

[0234] 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 S33: 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.

[0235] 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 S34: 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.

[0236] 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 S35: solvent concentration calculation step).

[0237] 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.

[0238] 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.

[0239] 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.

[0240] <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.

[0241] 19 is a diagram schematically illustrating a second example of a substrate processing system 1000 according to the fourth embodiment. In the second example, a concentration sensor Sn5 is provided in each cup-side recovery pipe 424. The concentration sensor Sn5 measures the solvent concentration of the mixed liquid flowing through the cup-side recovery pipe 424 and outputs the measurement result to the control unit 6.

[0242] The control unit 6 controls the recovery destination switching unit 500 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 concentration reference value, and when the solvent concentration is less than the concentration reference value, causes the recovery destination switching unit 500 to select the low-concentration tank Tk2L as the recovery destination, and when the solvent concentration is equal to or greater than the concentration reference value, causes the recovery destination switching unit 500 to select the high-concentration tank Tk2H as the recovery destination.

[0243] According to the second example, the concentration sensor Sn5 measures the solvent concentration, which allows the control unit 6 to 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 500, and more appropriately supply the mixed solution to the low-concentration tank Tk2L or the high-concentration tank Tk2H.

[0244] <Fifth embodiment> 20 is a diagram schematically illustrating a first example of a first dehydrator 60 according to the fifth embodiment. In the example of FIG. 20, the downstream end of a recovery pipe 51A (corresponding to the first pipe) and the downstream end of a recovery pipe 51B (corresponding to the second pipe) are connected to a concentration tank Tk1. In other words, the concentration tank Tk1 also functions as a junction tank Tk2. Therefore, it can be said that the concentration tank Tk1 is included in the junction section 50.

[0245] In the fifth embodiment, as shown in FIG. 20, the first dehydrator 60 further includes an agitator 95. The agitator 95 agitates the combined mixed liquid in the concentration tank Tk1. This makes it possible to make the concentration distribution of the combined mixed liquid in the concentration tank Tk1 uniform. Note that the concentration tank Tk1 also functions as the confluence tank Tk2, so the agitator 95 can also be said to be included in the confluence unit 50.

[0246] In the example of FIG. 20, the agitation unit 95 includes a bubbler pipe 951, an air supply pipe 952, and an air supply valve 953. The bubbler pipe 951 is provided in a position in the concentration tank Tk1 where it is immersed in the combined mixed liquid. The bubbler pipe 951 may extend, for example, horizontally. The bubbler pipe 951 may also be formed with a plurality of discharge ports 951a aligned along its longitudinal direction. In other words, the agitation unit 95 includes the discharge ports 951a that open into the concentration tank Tk1.

[0247] The downstream end of the air supply pipe 952 is connected to the bubbler pipe 951, and the upstream end of the air supply pipe 952 is connected to a gas supply source. The gas supply source supplies gas to the upstream end of the air supply pipe 952. The gas may be, for example, air or an inert gas. The inert gas may be, for example, a rare gas or nitrogen gas. An air supply valve 953 is inserted into the air supply pipe 952.

[0248] When the control unit 6 opens the air supply valve 953, gas flows into the bubbler tube 951 through the air supply pipe 952 and is discharged from the discharge port 951a into the mixed liquid in the concentration tank Tk1. This supplies a plurality of bubbles into the mixed liquid. The plurality of bubbles rises in the mixed liquid and is released from the liquid surface of the mixed liquid. This movement of the bubbles agitates the mixed liquid, making it possible to make the concentration distribution of the combined mixed liquid in the concentration tank Tk1 more uniform.

[0249] 21 is a flowchart showing an example of the operation of the organic solvent recovery unit 5 according to the fifth embodiment. First, as in the first to fourth embodiments, the confluence unit 50 confluences the low-concentration mixed liquid and the high-concentration mixed liquid to generate a confluence mixed liquid (step S41: confluence process). As an example, the control unit 6 opens the recovery valves 52A and 52B. As a result, the low-concentration mixed liquid from the substrate processing apparatus 100A and the high-concentration mixed liquid from the substrate processing apparatus 100B flow into the concentration tank Tk1. The low-concentration mixed liquid from the substrate processing apparatus 100A may be temporarily flowed into a low-concentration buffer tank, and the high-concentration mixed liquid from the substrate processing apparatus 100B may be temporarily flowed into a high-concentration buffer tank.

[0250] Next, the stirring unit 95 stirs the combined mixed liquid in the concentration tank Tk1 (step S42: stirring step). Specifically, the control unit 6 opens the air intake valve 953. As a result, the combined mixed liquid in the concentration tank Tk1 is stirred by a plurality of air bubbles. The control unit 6 closes the air intake valve 953, for example, when a predetermined stirring time has elapsed. The stirring time is set in advance to a time period long enough to make the concentration distribution of the combined mixed liquid sufficiently uniform.

[0251] Next, the first dehydrator 60 separates water from the combined mixed liquid to generate a reused liquid, similar to step S2 (step S43: dehydration step).

[0252] Next, the first dehydrator 60 supplies the reuse liquid to the supply tank Tk3 in the same manner as in step S3 (step S44: supply step).

[0253] As described above, in the fifth embodiment, the combined mixed liquid is agitated to reduce the variation in the concentration distribution of the combined mixed liquid, and then the first dehydrator 60 separates water from the combined mixed liquid using the first membrane separator 62. If the concentration distribution of the combined mixed liquid in the concentration tank Tk1 varies greatly, a mixed liquid with a low solvent concentration may instantaneously flow into the first membrane separator 62. In contrast, in the fifth embodiment, a combined mixed liquid with a more uniform concentration distribution flows into the first membrane separator 62. This reduces the possibility that a mixed liquid with a low solvent concentration will flow into the first membrane separator 62. In other words, the reliability of the organic solvent recovery unit 5 can be further improved.

[0254] Moreover, as described above, in the structure for discharging bubbles into the mixed liquid, no mechanical drive unit is present in the mixed liquid. For comparison, consider the case where a stirring drive unit such as a screw is provided in the mixed liquid. In this case, the screw operates mechanically in the mixed liquid, and particles may be generated due to friction, etc. This increases the concentration of impurities in the mixed liquid. In contrast, in the example of Figure 20, no drive unit is present in the mixed liquid, so the generation of particles can be avoided. In other words, an increase in the concentration of impurities in the mixed liquid can be avoided.

[0255] Fig. 22 is a diagram schematically illustrating a second example of the first dehydrator 60 according to the fifth embodiment. In the example of Fig. 22, the agitation unit 95 includes an agitation circulation pipe 96. The agitation circulation pipe 96 is a circulation pipe that returns the mixed liquid from the concentration tank Tk1 back to the concentration tank Tk1. The agitation unit 95 agitates the mixed liquid in the concentration tank Tk1 by circulating the mixed liquid through an agitation circulation path that includes the concentration tank Tk1 and the agitation circulation pipe 96.

[0256] 22 , a portion of the agitation circulation pipe 96 also serves as the first circulation pipe 63. Specifically, the first circulation pipe 63 includes a downstream common pipe 631, an upstream common pipe 632, and a first individual pipe 630, and the agitation circulation pipe 96 includes a downstream common pipe 631, an upstream common pipe 632, and an individual agitation pipe 960. In other words, the downstream common pipe 631 and the upstream common pipe 632 are also used as the first circulation pipe 63 and the agitation circulation pipe 96. The upstream end of the upstream common pipe 632 is connected to the concentration tank Tk1, and the downstream end of the upstream common pipe 632 is connected to the upstream end of the first individual pipe 630 and the upstream end of the individual agitation pipe 960. The downstream end of the downstream common pipe 631 is connected to the concentration tank Tk1, and the upstream end of the downstream common pipe 631 is connected to the downstream end of the first individual pipe 630 and the downstream end of the individual agitation pipe 960.

[0257] A pump 64 and a second switching valve 652 are inserted in the upstream common pipe 632, and a first switching valve 651 is inserted in the downstream common pipe 631. Therefore, the pump 64, the first switching valve 651, and the second switching valve 652 are used in common by the first circulation unit 61 and the agitation unit 95. A first membrane separator 62 is provided in the first individual pipe 630. The agitation individual pipe 960 also serves as a bypass pipe that bypasses the first membrane separator 62.

[0258] The first dehydrator 60 is also provided with a circulation switching unit 69. In the example of FIG. 22, the circulation switching unit 69 includes a switching valve 691 and a switching valve 692. The circulation switching unit 69 switches between a state in which the downstream common pipe 631 communicates with the upstream common pipe 632 through the first individual pipe 630 and a state in which the downstream common pipe 631 communicates with the upstream common pipe 632 through the individual agitation pipe 960. In the example of FIG. 22, the switching valve 691 is inserted in the first individual pipe 630, and the switching valve 692 is inserted in the individual agitation pipe 960.

[0259] The operation of the organic solvent recovery unit 5 according to the second example of the fifth embodiment is the same as that shown in FIG. 21. However, in step S42 (agitation step), the control unit 6 closes the switching valve 961, opens the first switching valve 651, the second switching valve 652, and the switching valve 692, and operates the pump 64. This causes the combined mixed liquid to circulate through the agitation circulation path. Therefore, the combined mixed liquid in the concentration tank Tk1 is agitated, and the concentration distribution of the combined mixed liquid becomes more uniform. Note that during this agitation circulation, the combined mixed liquid does not pass through the first membrane separator 62. This prevents the combined mixed liquid with a low solvent concentration from flowing into the first membrane separator 62 due to variations in the concentration distribution.

[0260] The control unit 6 may cause the agitation unit 95 to stop agitation, for example, when a predetermined agitation time has elapsed. In the next step S43 (spin-drying step), the control unit 6 closes the switching valve 692 and opens the switching valve 691 and the discharge valve 67. This causes the combined mixed liquid to circulate through the first circulation path and undergo separation processing.

[0261] As described above, in the second example of the fifth embodiment, the combined mixed liquid is agitated to make the concentration distribution more uniform, and then the first dehydrator 60 separates water from the combined mixed liquid using the first membrane separator 62. This reduces the possibility that a mixed liquid with a low solvent concentration will flow into the first membrane separator 62. Furthermore, in the second example, an increase in the impurity concentration in the mixed liquid can be suppressed compared to when a drive mechanism such as a screw is provided in the concentration tank Tk1. Furthermore, in the above example, the pump 64 is used by both the first circulation section 61 and the agitation section 95, thereby reducing the manufacturing cost and device size of the organic solvent recovery section 5.

[0262] Sixth Embodiment 23 is a diagram showing an example of a substrate processing system 1000 according to the sixth embodiment. The organic solvent recovery unit 5 according to the sixth embodiment differs from the organic solvent recovery unit 5 according to the first to fifth embodiments in that a second dehydrator 70 is provided.

[0263] The second dehydrator 70 is provided upstream of the confluence 50. In the example of FIG. 23 , the downstream end of the recovery pipe 51B is connected to the second dehydrator 70. Therefore, the high-concentration mixed liquid from the substrate processing apparatus 100B flows into the second dehydrator 70. The second dehydrator 70 separates water from the high-concentration mixed liquid to increase the solvent concentration of the high-concentration mixed liquid. For example, the solvent concentration of the high-concentration mixed liquid discharged from the substrate processing apparatus 100B is approximately 70 wt %, and the second dehydrator 70 increases the solvent concentration of the high-concentration mixed liquid by, for example, 10 wt % or more. A specific example of the second dehydrator 70 will be described later. In the example of FIG. 23 , the second dehydrator 70 is connected to the upstream end of the liquid supply pipe 78, and the downstream end of the liquid supply pipe 78 is connected to the confluence 50. The second dehydrator 70 supplies the separated high-concentration mixed liquid to the confluence 50 through the liquid supply pipe 78.

[0264] The confluence unit 50 merges the low-concentration mixed liquid from the substrate processing apparatus 100A and the high-concentration mixed liquid from the second dehydrator 70. Because the second dehydrator 70 increases the solvent concentration of the high-concentration mixed liquid, the confluence unit 50 can more reliably ensure that the solvent concentration of the merged mixed liquid is equal to or greater than the concentration reference value through this merging. In other words, the organic solvent recovery unit 5 can reduce the amount of new liquid used while still ensuring that the solvent concentration of the merged mixed liquid is equal to or greater than the concentration reference value.

[0265] 24 is a diagram schematically illustrating a first example of second dehydrator 70. In the example of FIG. 24, second dehydrator 70 includes a distillation column 701 and a cooler 702. The downstream end of recovery piping 51B is connected to distillation column 701, and the upstream end of steam piping 7031 is connected to, for example, an upper portion of distillation column 701. The downstream end of steam piping 7031 is connected to cooler 702.

[0266] Distillation column 701 includes a heating section (not shown) that heats the mixed liquid. 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. Distillation column 701 vaporizes the mixed liquid and supplies vapor containing a large amount of organic solvent to the upstream end of vapor pipe 7031. The vapor that flows into the upstream end of vapor pipe 7031 may contain not only organic solvent but also water, but the solvent concentration is higher than the solvent concentration before entering distillation column 701. This vapor flows into cooler 702 through vapor pipe 7031.

[0267] The upstream end of liquid piping 7032 is also connected to cooler 702. Cooler 702 cools and condenses vapor. Cooler 702 may have, for example, a heat exchanger. 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 7032. The solvent concentration of this mixed liquid is higher than the solvent concentration of the mixed liquid immediately before distillation column 701.

[0268] As shown in FIG. 24, second dehydrator 70 may include multiple distillation columns 701 and multiple coolers 702. In the example of FIG. 24, pairs of distillation columns 701 and coolers 702 are connected in series. In the example of FIG. 24, 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 7031 connects distillation column 701a and cooler 702a, and liquid piping 7032 connects cooler 702a and distillation column 701b. Steam from distillation column 701a is condensed in cooler 702a to form a liquid mixture, and the liquid mixture from cooler 702a is supplied to distillation column 701b. The upstream end of vapor pipe 7033 is connected to, for example, the upper part of distillation column 701b, and the downstream end of vapor pipe 7033 is connected to 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 liquid supply pipe 78 is connected to cooler 702b, and the mixed liquid from cooler 702b is supplied to junction 50 through liquid supply pipe 78.

[0269] The second dehydrator 70 may include a pump and a valve (not shown). For example, a liquid supply valve may be inserted in the liquid supply pipe 78, and a pump may be inserted in the liquid supply pipe 7032.

[0270] Fig. 25 is a diagram schematically illustrating a second example of the second dehydrator 70. In the example of Fig. 25, the second dehydrator 70 includes an ultrasonic atomization separator 704. The downstream end of the recovery pipe 51A, the upstream end of the liquid delivery pipe 78, and the upstream end of the separation and discharge pipe 705 are connected to the ultrasonic atomization separator 704.

[0271] The mixed liquid flows into ultrasonic atomization separator 704 through recovery pipe 51B. 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.

[0272] 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 liquid supply pipe 78 is connected to the top of the separation container. The organic solvent mist is supplied to the confluence 50 through the liquid supply pipe 78. A tank for confluence of the organic solvent mist may be provided between the separation container and the liquid supply pipe 78.

[0273] FIG. 26 is a schematic diagram showing a third example of the second dehydrator 70. In the example of FIG. 26, the second dehydrator 70 includes a 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.

[0274] 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.

[0275] 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.

[0276] The second separation membrane 72c has a concentration lower limit different from that of the first separation membrane 62c. For example, the second separation membrane 72c has a higher concentration lower limit than that of the first separation membrane 62c. The second separation membrane 72c has a concentration lower limit equal to or lower than the solvent concentration of the mixed solution from the substrate processing apparatus 100B. Here, 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. The differences in the lattice structure of the zeolite membrane can be indicated by its type (also called a structure code). For example, zeolite membrane types include LTA, CHA, and DDR. The concentration lower limit of the LTA zeolite membrane is, for example, about 50 wt%, the concentration lower limit of the CHA zeolite membrane is, for example, about 70 wt%, and the concentration lower limit of the DDR zeolite membrane is, for example, about 90 wt%.

[0277] As an example, the second separation membrane 72c is a CHA-type zeolite membrane, and the first separation membrane 62c is an LTA-type zeolite membrane. In this case, the lower limit of the concentration of the second separation membrane 72c is about 70 wt%, and here, the solvent concentration of the high-concentration mixed solution from the substrate processing apparatus 100B is about 70 wt% or more. The lower limit of the concentration of the first separation membrane 62c is about 50 wt%. 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 whose lower limit of the concentration is higher than that of the first-type zeolite membrane.

[0278] The separation constant of the second separation membrane 72c is higher than that of the first separation membrane 62c. 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.

[0279] 26, the second dehydrator 70 includes a concentration tank Tk4 and a second circulation unit 71. The second circulation unit 71 includes a second circulation piping 73, a pump 74, a first switching valve 751, and a second switching valve 752. The concentration tank Tk4, the second circulation piping 73, the pump 74, the first switching valve 751, and the second switching valve 752 are similar to the concentration tank Tk1, the first circulation piping 63, the pump 64, the first switching valve 651, and the second switching valve 652, respectively.

[0280] In the example of Figure 26, the second dehydrator 70 separates water from the mixed liquid using the second membrane separator 72, so the second dehydrator 70 can increase the solvent concentration of the mixed liquid with higher efficiency.

[0281] 26, the second dehydrator 70 further includes a liquid supply pipe 78 and a liquid supply valve 79. The upstream end of the liquid supply pipe 78 is connected to the second circulation pipe 73 between the first switching valve 751 and the pump 74. The liquid supply valve 79 is inserted in the liquid supply pipe 78. The upstream end of the liquid supply pipe 78 may be connected to the concentration tank Tk4, similar to the liquid supply pipe 53.

[0282] When 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, the mixed liquid circulates through a second circulation path including the concentration tank Tk4 and the second circulation piping 73. Because the mixed liquid passes through the second membrane separator 72, the second dehydrator 70 can increase the solvent concentration of the mixed liquid in the concentration tank Tk4.

[0283] The second dehydrator 70 according to the third example can increase the solvent concentration of the mixed liquid more efficiently than the second dehydrators 70 according to the first and second examples. Furthermore, if the separation constant of the second separation membrane 72c is larger than the separation constant of the first separation membrane 62c, the second dehydrator 70 can increase the solvent concentration of the mixed liquid even more efficiently.

[0284] In the above example, the second dehydrator 70 receives the high-concentration mixed liquid from the substrate processing apparatus 100B, but this is not necessarily limited to this. The second dehydrator 70 may be connected to the downstream end of the recovery pipe 51A, for example. That is, the second dehydrator 70 may increase the solvent concentration of the low-concentration mixed liquid from the substrate processing apparatus 100A. For example, the solvent concentration of the low-concentration mixed liquid from the substrate processing apparatus 100A is 30 wt %, and the second dehydrator 70 increases the solvent concentration of the low-concentration mixed liquid by, for example, about 10 wt % and supplies the mixed liquid to the confluence section 50. This also allows the organic solvent recovery section 5 to more reliably produce a confluence mixed liquid having a solvent concentration equal to or higher than the reference concentration value. In addition, if the second dehydrator 70 includes the second membrane separator 72, the second separation membrane 72c is a separation membrane having a concentration lower limit lower than the concentration lower limit of the first separation membrane 62c. The lower limit of the concentration of the second separation membrane 72c is set lower than the solvent concentration of the low-concentration mixed liquid before separation. On the other hand, when the second dehydrator 70 has at least one of the distillation column 701 and the ultrasonic atomization separator 704, the lower limit of the concentration of the second dehydrator 70 is very low, for example, almost zero. For this reason, the second dehydrator 70 can be easily applied to low-concentration mixed liquids.

[0285] As described above, the second dehydrator 70 separates water from the mixed liquid flowing, for example, through one of the recovery pipes 51A (corresponding to the first pipe) and 51B (corresponding to the second pipe), thereby increasing the solvent concentration of the mixed liquid, and the confluence section 50 merges the mixed liquid that has passed through, for example, the other of the recovery pipes 51A and 51B with the mixed liquid from the second dehydrator 70.

[0286] Seventh Embodiment 27 is a diagram schematically illustrating an example of a substrate processing system 1000 according to a seventh embodiment. The organic solvent recovery unit 5 according to the seventh embodiment differs from the organic solvent recovery unit 5 according to the sixth embodiment in the presence or absence of a third dehydrator 700. In addition, in the seventh embodiment, the second dehydrator 70 includes a second membrane separator 72.

[0287] The third dehydrator 700 is provided in a stage preceding the second dehydrator 70. The lower limit of the concentration of the third dehydrator 700 is lower than the lower limit of the concentration of the second separation membrane 72c. In the example of FIG. 27, the third dehydrator 700 is connected to the recovery pipe 51B, and the high-concentration mixed solution from the substrate processing apparatus 100B is supplied to the third dehydrator 700. Here, the solvent concentration of the high-concentration mixed solution from the substrate processing apparatus 100B is equal to or higher than the lower limit of the concentration of the second separation membrane 72c. For example, the solvent concentration of the high-concentration mixed solution is about 80 wt%, and the lower limit of the concentration of the second separation membrane 72c is 70 wt%.

[0288] The third dehydrator 700 separates water from the high-concentration mixed solution from the substrate processing apparatus 100B and increases the solvent concentration of the high-concentration mixed solution to or above the lower limit concentration value of the second separation membrane 72c. The third dehydrator 700 may have a configuration similar to that shown in Figure 24 or 25. The third dehydrator 700 supplies the separated high-concentration mixed solution to the second dehydrator 70 through a liquid delivery pipe 780.

[0289] As in the sixth embodiment, the second dehydrator 70 separates water from the high-concentration mixed solution using a second membrane separator 72, thereby further increasing the solvent concentration of the high-concentration mixed solution. For example, the second dehydrator 70 increases the solvent concentration of the high-concentration mixed solution to 80 wt %. The second dehydrator 70 supplies the separated high-concentration mixed solution to the confluence section 50.

[0290] As described above, in the seventh embodiment, the third dehydrator 700 increases the solvent concentration of the mixed liquid to or above the concentration lower limit of the second separation membrane 72c. Therefore, the second dehydrator 70 can further increase the solvent concentration of the mixed liquid with high reliability and efficiency by using the second membrane separator 72. Furthermore, in the seventh embodiment, the concentration lower limit of the second separation membrane 72c is different from the concentration lower limit of the first separation membrane 62c. Therefore, a separation membrane suitable for the solvent concentration range of the mixed liquid flowing into the second membrane separator 72 can be used. For example, a separation membrane having a concentration lower limit higher than the solvent concentration of the first separation membrane 62c can be used for the second separation membrane 72c. Therefore, a separation membrane with a high concentration lower limit and a high separation constant can be used for the second separation membrane 72c.

[0291] <Eighth embodiment> 28 is a diagram schematically illustrating an example of a substrate processing system 1000 according to an eighth embodiment. The organic solvent recovery unit 5 according to the eighth embodiment differs from the organic solvent recovery unit 5 according to the sixth embodiment in the presence or absence of a third dehydrator 700 and a dehydration switching unit 93. In addition, in the eighth embodiment, the second dehydrator 70 includes a second membrane separator 72.

[0292] The third dehydrator 700 is provided in a stage preceding the confluence section 50. The lower limit of the concentration of the third dehydrator 700 is lower than the lower limit of the concentration of the second separation membrane 72c.

[0293] 28, the second dehydrator 70 and the third dehydrator 700 are connected to the substrate processing apparatus 100 (here, the substrate processing apparatus 100B) through a dehydration switching unit 93. The dehydration switching unit 93 switches the supply destination of the high-concentration mixed solution from the substrate processing apparatus 100B between the second dehydrator 70 and the third dehydrator 700. In the example of FIG. 28, the dehydration switching unit 93 includes a recovery pipe 51B and a switching valve unit 520B. As in FIG. 9, the recovery pipe 51B includes a common recovery pipe 510B, a first branch pipe 511B, and a second branch pipe 512B. However, the downstream end of the first branch pipe 511B is connected to the second dehydrator 70, and the downstream end of the second branch pipe 512B is connected to the third dehydrator 700. As in FIG. 9, the switching valve unit 520B includes a switching valve 521B and a switching valve 522B. The common recovery pipe 510B is provided with a concentration sensor Sn5B.

[0294] The control unit 6 compares the solvent concentration of the high-concentration mixed solution from the substrate processing apparatus 100B measured by the concentration sensor Sn5B with a second concentration reference value (described below). The second concentration reference value is set to be equal to or greater than the concentration lower limit of the second separation membrane 72c. When the solvent concentration is equal to or greater than the second concentration reference value, the control unit 6 controls the dehydration switching unit 93 to select the second dehydrator 70 as the supply destination. Specifically, the control unit 6 opens the switching valve 521B while keeping the switching valve 522B closed. This supplies the high-concentration mixed solution to the second dehydrator 70. The second dehydrator 70 separates water from the high-concentration mixed solution using the highly efficient second membrane separator 72, thereby increasing the solvent concentration of the high-concentration mixed solution. The second dehydrator 70 supplies the separated high-concentration mixed solution to the confluence unit 50 via the liquid supply pipe 78.

[0295] On the other hand, when the solvent concentration is less than the second concentration reference value, the control unit 6 causes the spinning switching unit 93 to select the third dehydrator 700 as the supply destination. Specifically, the control unit 6 closes the switching valve 521B and opens the switching valve 522B. As a result, the high-concentration mixed solution is supplied to the third dehydrator 700. The third dehydrator 700 separates water from the high-concentration mixed solution and increases the solvent concentration of the high-concentration mixed solution. The third dehydrator 700 supplies the separated high-concentration mixed solution to the confluence unit 50 through the liquid supply pipe 780.

[0296] The lower limit of the concentration of the third dehydrator 700 is equal to or lower than the solvent concentration of the high-concentration mixed solution before separation. The third dehydrator 700 may have the configuration shown in Fig. 24 or 25, for example. Although the energy efficiency of the third dehydrator 700 is lower than that of the second dehydrator 70, the third dehydrator 700 can appropriately separate water from a high-concentration mixed solution having a solvent concentration below the lower limit of the concentration of the second separation membrane 72c, thereby increasing the solvent concentration.

[0297] <Ninth embodiment> 29 is a diagram schematically illustrating an example of an organic solvent recovery unit 5 according to the ninth embodiment. The organic solvent recovery unit 5 according to the ninth embodiment differs from the organic solvent recovery unit 5 according to the eighth embodiment in the configuration of the third dehydrator 700 and the presence or absence of a circulation switching unit 790.

[0298] The third dehydrator 700 includes a third circulation unit 710. The third circulation unit 710 includes a third membrane separator 720, a third circulation piping 730, a pump 74, and a second switching valve 752. In the example of Fig. 29, part of the second circulation piping 73 and part of the third circulation piping 730 are used in common.

[0299] 29, the second circulation pipe 73 includes a downstream common pipe 731, a second individual pipe 733, and an upstream common pipe 732, which is an example of a common circulation pipe, and the third circulation pipe 730 includes a downstream common pipe 631, a third individual pipe 734, and an upstream common pipe 732. In other words, the downstream common pipe 731 and the upstream common pipe 732 are shared by the second circulation pipe 73 and the third circulation pipe 730. The upstream end of the upstream common pipe 732 is connected to, for example, the bottom of the concentration tank Tk4, and the downstream end of the downstream common pipe 731 is connected to, for example, the top of the concentration tank Tk4. The upstream ends of the second individual pipe 733 and the third individual pipe 734 are connected to the downstream end of the upstream common pipe 732, and the downstream ends of the second individual pipe 733 and the third individual pipe 734 are connected to the upstream end of the downstream common pipe 731. The concentration tank Tk4 and the second circulation pipe 73 form a second circulation path, and the concentration tank Tk4 and the third circulation pipe 730 form a third circulation path.

[0300] The second individual pipe 733 is provided with a second membrane separator 72, and the third individual pipe 734 is provided with a third membrane separator 720. The third membrane separator 720 separates water from the mixed liquid to increase the solvent concentration of the mixed liquid. The third membrane separator 720 includes a third mixing path 720a, a third water path 720b, and a third separation membrane 720c. The third mixing path 720a, the third water path 720b, and the third separation membrane 720c are similar to the first mixing path 62a, the first water path 62b, and the first separation membrane 62c, respectively.

[0301] A portion of the water in the mixed liquid that flows into the third mixing path 720a passes through the third separation membrane 720c and flows into the third water path 720b. The separated liquid that flows into the third water path 720b is discharged to the outside (for example, a wastewater treatment unit of a factory facility) through the separation discharge pipe 760. A discharge valve 770 is inserted into the separation discharge pipe 760.

[0302] The solvent concentration of the mixed liquid that has passed through the third mixing path 720a becomes higher than the solvent concentration of the mixed liquid immediately before it entered the third mixing path 720a.

[0303] The third separation membrane 720c has a lower concentration limit lower than that of the second separation membrane 72c and is equal to or lower than the solvent concentration of the mixed solution from the substrate processing apparatus 100B. The second separation membrane 72c and the third separation membrane 720c are, for example, zeolite membranes. That is, the second separation membrane 72c is a second-type zeolite membrane, and the third separation membrane 720c is a third-type zeolite membrane having a lower concentration limit than the second-type zeolite membrane. In addition, the separation constant of the second separation membrane 72c is higher than that of the third separation membrane 720c.

[0304] 29, the pump 74 and the second switching valve 752 are inserted in the upstream common pipe 732. Therefore, the pump 74 and the second switching valve 752 are shared by the second circulation section 71 and the third circulation section 710.

[0305] In the example of FIG. 29 , the circulation switching unit 790 includes a first three-way valve 791 and a second three-way valve 792. The circulation switching unit 790 switches the circulation path between the second circulation path and the third circulation path. Specifically, the circulation switching unit 790 switches between a second circulation state and a third circulation state, which will be described below. The second circulation state is a state in which the downstream common pipe 731 and the upstream common pipe 732 communicate with each other through the second individual pipe 733. In the second circulation state, the mixed liquid circulates through the second circulation path including the concentration tank Tk4 and the second circulation pipe 73. Therefore, the mixed liquid is separated by the second membrane separator 72 on the second circulation path. In other words, the second circulation state corresponds to a state in which the mixed liquid is supplied to the second dehydrator 70. The third circulation state is a state in which the downstream common pipe 731 and the upstream common pipe 732 communicate with each other through the third individual pipe 734. In the third circulation state, the mixed liquid circulates through a third circulation path including the concentration tank Tk4 and the third circulation piping 730. Therefore, the mixed liquid is separated by the third membrane separator 720. In other words, the third circulation state corresponds to a state in which the mixed liquid is supplied to the third dehydrator 700.

[0306] 29 , the first three-way valve 791 is connected to the upstream end of the downstream common pipe 731, the downstream end of the second individual pipe 733, and the downstream end of the third individual pipe 734. The first three-way valve 791 switches between a second downstream circulation state in which the downstream common pipe 731 is connected to the second individual pipe 733, and a third downstream circulation state in which the downstream common pipe 731 is connected to the third individual pipe 734. The second three-way valve 792 is connected to the downstream end of the upstream common pipe 732, the upstream end of the second individual pipe 733, and the upstream end of the third individual pipe 734. The second three-way valve 792 switches between a second upstream circulation state in which the upstream common pipe 732 is connected to the second individual pipe 733, and a third upstream circulation state in which the upstream common pipe 732 is connected to the third individual pipe 734.

[0307] 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 circulation switching unit 790 selects the second circulation state. When the control unit 6 causes the first three-way valve 791 to select the third downstream circulation state and the second three-way valve 792 to select the third upstream circulation state, the mixed liquid circulates through the third circulation path. That is, the circulation switching unit 790 selects the third circulation state.

[0308] In the ninth embodiment, the control unit 6 controls the circulation switching unit 790 based on, for example, the solvent concentration of the high-concentration mixed solution from the substrate processing apparatus 100B. In the example of FIG. 29, a concentration sensor Sn5B is provided in the common recovery pipe 510B. The control unit 6 may control the circulation switching unit 790 based on the solvent concentration of the mixed solution measured by the concentration sensor Sn5B. Specifically, when the solvent concentration is equal to or greater than a second concentration reference value, the control unit 6 controls the circulation switching unit 790 to select the second circulation state. Then, the control unit 6 circulates the mixed solution through the second circulation unit 71. For example, the control unit 6 opens the second switching valve 752 and the discharge valve 77 and operates the pump 74. Since the mixed solution continues to flow into the second membrane separator 72 of the second circulation path, the solvent concentration of the mixed solution increases over time. The control unit 6 circulates the mixed solution through the second circulation unit 71 until the solvent concentration of the mixed solution reaches a predetermined concentration (e.g., 80 wt%).

[0309] On the other hand, when the solvent concentration measured by the concentration sensor Sn5B is equal to or greater than the concentration lower limit of the third separation membrane 720c and less than the second concentration reference value, the control unit 6 controls the circulation switching unit 790 to select the third circulation state. Then, the control unit 6 circulates the mixed liquid through the third circulation unit 710. As an example, the control unit 6 opens the second switching valve 752 and the discharge valve 770 and operates the pump 74. Because the mixed liquid continues to flow into the third membrane separator 720 of the third circulation path, the solvent concentration of the mixed liquid increases over time.

[0310] The control unit 6 may circulate the mixed liquid through the third circulation unit 710 until the solvent concentration of the mixed liquid reaches a predetermined concentration (for example, 80 wt %) or more.

[0311] Alternatively, when the solvent concentration of the mixed liquid reaches or exceeds the lower limit of the concentration of the second separation membrane 72c (e.g., 70 wt%), the control unit 6 may stop the circulation by the third circulation unit 710 and start the circulation by the second circulation unit 71. This allows the second circulation unit 71 to continue increasing the solvent concentration of the mixed liquid. The second circulation unit 71 may circulate the mixed liquid until the solvent concentration of the mixed liquid reaches or exceeds a predetermined concentration (e.g., 80 wt%).

[0312] As described above, in the ninth embodiment, even when the solvent concentration of the mixed solution is below the lower limit of the second separation membrane 72c, the third dehydrator 700 separates water from the mixed solution using the highly efficient third membrane separator 720. Furthermore, when the solvent concentration of the mixed solution is equal to or greater than the lower limit of the second separation membrane 72c, the second dehydrator 70 separates water from the mixed solution using the second separation membrane 72c, which has a higher separation constant than the third separation membrane 720c. This allows the organic solvent recovery unit 5 to increase the solvent concentration of the mixed solution with even higher efficiency.

[0313] As described above, the organic solvent recovery apparatus (organic solvent recovery unit 5), the substrate processing system 1000, 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.

[0314] 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]

[0315] 1 Load Port No. 1, Load Port No. 2 (Load Port) 100 Substrate processing apparatus 100A First Substrate Processing Equipment 100B Second substrate processing apparatus 2 First transfer section, second transfer section (indexer robot) 3 First transfer unit, second transfer unit (main transfer robot) 4. First processing unit, second processing unit (processing unit) 41 Substrate holder (spin chuck) 42 cups 430 Discharge part 50 Junction 500 Collection destination switching unit 500A First collection destination switching unit 500B Second collection destination switching unit 51A First pipe (recovery pipe) 51B 2nd pipe, 3rd pipe (recovery pipe) 51L 1st piping (low concentration piping) 51H Second pipe (high concentration pipe) 550 Supply source switching unit 56 Second piping, new liquid piping 580 New liquid switching part 6 Control Unit 60 1st dehydrator 62 1st membrane separator 62c 1st separation membrane 70 Second dehydrator 700 3rd dehydrator 701 Distillation tower 704 Ultrasonic Atomization Separator 72 Second membrane separator 720 Third membrane separator 72c 2nd separation membrane 720c 3rd separation membrane 73 2nd circulation piping 790 Circulation Switching Unit 90 Regulator 95 Stirring section 951 Bubbler tube 96 Stirring circulation piping D1 Recipe Information D2 Correspondence information Sn5 concentration sensor Tk1 tank (concentration tank) Tk2 Tank (Confluence Tank) Tk21 tank, first junction tank Tk22 tank, second junction tank Tk2L low concentration tank Tk2H High concentration tank Tk3 Supply Tank S1 Confluence process (step) S2 Dehydration process (step) W substrate

Claims

1. a first pipe through which a mixed liquid containing an organic solvent and water flows from a first processing unit for processing a substrate; a second pipe through which the organic solvent or the mixed liquid flows; a confluence section that combines the mixed liquid having a solvent concentration less than a predetermined concentration reference value that has passed through the first pipe with the liquid having a solvent concentration equal to or greater than the concentration reference value that has passed through the second pipe to generate a combined mixed liquid that is the mixed liquid having a solvent concentration equal to or greater than the concentration reference value; a first dehydrator including a first membrane separator that includes a first separation membrane having a concentration lower limit value of an applicable range of solvent concentration that is the concentration reference value, and that separates water from the combined mixed liquid from the confluence part to increase the solvent concentration of the combined mixed liquid; An organic solvent recovery device comprising:

2. The organic solvent recovery apparatus according to claim 1, a third pipe through which the mixed liquid discharged from a second processing unit for processing a substrate flows; the liquid is a new organic solvent that has not yet been used in processing the substrate, the confluence section includes an adjuster that adjusts a confluence ratio of the mixed liquid that has passed through the first pipe, the mixed liquid that has passed through the third pipe, and the new liquid that has passed through the second pipe in the organic solvent recovery apparatus.

3. The organic solvent recovery apparatus according to claim 2, The confluence portion is a first junction tank and a second junction tank; a recovery destination switching unit that switches a recovery destination of the mixed liquid that has passed through the first pipe and the third pipe between the first junction tank and the second junction tank; a new liquid switching unit that switches the supply destination of the new liquid between the first junction tank and the second junction tank; a supply source switching unit that switches a supply source that supplies the mixed liquid to the first dehydrator between the first junction tank and the second junction tank; An organic solvent recovery device comprising:

4. The organic solvent recovery apparatus according to claim 1, a low concentration tank and a high concentration tank; a first recovery destination switching unit that switches between a first low-concentration state in which the first treatment unit is connected to the low-concentration tank and a first high-concentration state in which the first treatment unit is connected to the high-concentration tank; a control unit that causes the first recovery destination switching unit to select the first low concentration state when the solvent concentration of the mixed solution from the first processing unit is less than the concentration reference value, and causes the first recovery destination switching unit to select the first high concentration state when the solvent concentration of the mixed solution from the first processing unit is equal to or greater than the concentration reference value; Equipped with the first pipe connects the low-concentration tank and the junction, and the second pipe connects the high-concentration tank and the junction; The organic solvent recovery apparatus, wherein the confluence section includes an adjuster that adjusts a confluence ratio of the mixed liquid passing through the first pipe and the mixed liquid passing through the second pipe.

5. The organic solvent recovery apparatus according to claim 4, a new liquid pipe through which new organic solvent that has not yet been used to process the substrate flows; the confluence portion mixes the mixed liquid from the low-concentration tank via the first piping, the mixed liquid from the high-concentration tank via the second piping, and the new liquid via the new liquid piping; The adjuster adjusts the confluence ratio of the mixed liquid passing through the first pipe, the mixed liquid passing through the second pipe, and the new liquid passing through the new liquid pipe in the organic solvent recovery apparatus.

6. The organic solvent recovery apparatus according to claim 4, a second recovery destination switching unit that switches between a second low-concentration state in which a second processing unit that processes a substrate is connected to the low-concentration tank and a second high-concentration state in which the second processing unit is connected to the high-concentration tank; the control unit causes the second recovery destination switching unit to select the second low concentration state when the solvent concentration of the mixed solution from the second processing unit is less than the concentration reference value, and causes the second recovery destination switching unit to select the second high concentration state when the solvent concentration of the mixed solution from the second processing unit is equal to or greater than the concentration reference value.

7. The organic solvent recovery apparatus according to claim 4, a storage unit that stores recipe information indicating processing details for the substrate to be performed by the first processing unit; The control unit calculates the solvent concentration of the mixed liquid discharged from the first processing unit based on the recipe information.

8. The organic solvent recovery apparatus according to claim 7, The first 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 first 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 first 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.

9. The organic solvent recovery apparatus according to claim 4, a concentration sensor for measuring a solvent concentration of the mixed liquid; The control unit controls the first recovery destination switching unit based on the solvent concentration of the mixed liquid measured by the concentration sensor.

10. The organic solvent recovery apparatus according to any one of claims 1 to 4, The confluence portion is a tank into which the mixed liquid flows via the first pipe and the second pipe; a stirring unit that stirs the mixed liquid stored in the tank; An organic solvent recovery device comprising:

11. The organic solvent recovery apparatus according to claim 10, The organic solvent recovery apparatus, wherein the stirring unit includes a bubbler tube that ejects bubbles into the mixed liquid stored in the tank.

12. The organic solvent recovery apparatus according to claim 10, The organic solvent recovery apparatus, wherein the agitation unit includes an agitation circulation pipe connected to the tank, and the mixed liquid is circulated through the tank and the agitation circulation pipe.

13. The organic solvent recovery apparatus according to any one of claims 1 to 4, a second dehydrator that separates water from the mixed liquid flowing through one of the first pipe and the second pipe to increase a solvent concentration in the mixed liquid; The confluence section merges the mixed liquid that has passed through the other of the first pipe and the second pipe with the mixed liquid from the second dehydrator.

14. The organic solvent recovery apparatus according to claim 13, The organic solvent recovery apparatus, wherein the second dehydrator includes at least one of a distillation column and an ultrasonic atomization separator.

15. The organic solvent recovery apparatus according to claim 13, The second dehydrator includes a second membrane separator that includes a second separation membrane and separates water from the mixed liquid to increase the solvent concentration of the mixed liquid, The organic solvent recovery apparatus, wherein the concentration lower limit value of the second separation membrane is different from the concentration lower limit value of the first separation membrane.

16. The organic solvent recovery apparatus according to claim 15, Further provided is a third dehydrator provided in a stage preceding the second dehydrator, the third dehydrator separates water from the mixed liquid flowing through one of the first pipe and the second pipe, increases the solvent concentration of the mixed liquid to or above the lower limit concentration value of the second separation membrane, and supplies the mixed liquid to the second dehydrator.

17. The organic solvent recovery apparatus according to claim 15, The second dehydrator is a concentration tank that stores the mixed liquid from the first pipe or the second pipe; a second circulation pipe connected to the concentration tank and equipped with the second membrane separator; a third circulation pipe connected to the concentration tank and equipped with a third membrane separator; a circulation switching unit that switches between a second circulation state in which the mixed liquid circulates through the concentration tank and the second circulation pipe and a third circulation state in which the mixed liquid circulates through the concentration tank and the third circulation pipe; Control unit and Including, the third membrane separator includes a third separation membrane; the concentration lower limit value of the third separation membrane is lower than the concentration lower limit value of the second separation membrane, The separation constant of the second separation membrane is higher than the separation constant of the third separation membrane; the control unit causes the circulation switching unit to select the third circulation state when the solvent concentration of the mixed solution in the concentration tank is less than the concentration lower limit value of the second separation membrane and is equal to or greater than the concentration lower limit value of the third separation membrane, and causes the circulation switching unit to select the second circulation state when the solvent concentration of the mixed solution in the concentration tank is equal to or greater than the concentration lower limit value of the second separation membrane.

18. The organic solvent recovery apparatus according to any one of claims 2, 3 and 6, a first substrate processing apparatus including a first load port, a plurality of the first processing units, and a first transport unit that transports substrates between the first load port and the plurality of first processing units; a second substrate processing apparatus including a second load port, a plurality of the second processing units, and a second transport unit that transports substrates between the second load port and the plurality of second processing units; A substrate processing system comprising:

19. a confluence step of confluence of a mixed solution containing an organic solvent and water discharged from a first processing unit for processing a substrate with the organic solvent or the mixed solution to generate the mixed solution having a concentration equal to or greater than a reference value; a dehydration step of separating water from the mixed liquid produced in the combining step using a first membrane separator including a first separation membrane whose lower limit value of the applicable range of solvent concentration is the concentration reference value, thereby increasing the solvent concentration of the mixed liquid; The organic solvent recovery method comprises:

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