Wafer storage container cleaning device

Abstract

To output information concerning particles that indicates the degree of cleanness in the storage space of a cleaned wafer storage container.SOLUTION: Provided is a wafer storage container cleaning device that cleans a wafer storage container, said cleaning device comprising: a cleaning tank body 5a that has a body opening and a cleaning space that communicates with the body opening; a lid unit 5b that is openably-closably provided to the body opening; a placement unit 5c that is disposed in the cleaning space, and on which a shell 20a is placed facing a shell opening, and in which an open hole 5c_1 communicating with a storage space is formed in a section that faces the shell opening; a first discharge unit 5d that discharges a cleaning liquid to the storage space of the shell; a second discharge unit 5e that discharges a cleaning liquid to an outside section of the shell; a first ejection unit 5g that communicates with the open hole and ejects the cleaning liquid having been discharged to the storage space of the shell; a second ejection unit 5h that ejects the cleaning liquid having gone through the outside section of the shell; and a particle measurement unit that measures particles of the cleaning liquid ejected by the first ejection unit.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] Embodiments of the present invention relate to a wafer storage container cleaning device.

Background Art

[0002] Conventionally, there is a wafer storage container cleaning device that cleans and dries wafer storage containers such as FOUP (Front Opening Unified Pod) and FOSB (Front Opening Shipping Box) that store (accommodate) semiconductor wafers.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In a wafer storage container, impurities (particles) may adhere to the storage space where the semiconductor wafers are stored when the door (lid) is opened and closed or when the semiconductor wafers are taken in and out. Therefore, at least the storage space is cleaned by a wafer storage container cleaning device. Here, the user has a desire to grasp the degree of cleanliness of the storage space of the wafer storage container after being cleaned by the wafer storage container cleaning device based on information related to particles.

[0005] The present invention has been made to solve the above problems, and an object thereof is to provide a wafer storage container cleaning device capable of detecting information related to particles indicating the degree of cleanliness of the storage space of a cleaned wafer storage container.

Means for Solving the Problems

[0006] To solve the above-mentioned problems and achieve the objective, a wafer storage container cleaning apparatus according to one aspect of the present invention is a wafer storage container cleaning apparatus for cleaning a wafer storage container having a shell having a shell opening and a storage space for storing semiconductor wafers and communicating with the shell opening, and a door that is attached to the shell opening so as to be openable and closable, the apparatus comprising: a cleaning tank body having a main body opening and a cleaning space communicating with the main body opening, a lid portion that is provided to openable and closable with respect to the main body opening, a mounting portion provided in the cleaning space and on which the shell is placed facing the shell opening, and on which a through hole communicating with the storage space is formed in the portion facing the shell opening, and the shell in the storage space One fluid Cleaning solution and two-fluid cleaning solution of Switch A first discharge unit for discharging, a second discharge unit for discharging cleaning liquid to the outer portion of the shell, a first discharge unit communicating with the through hole and for discharging the cleaning liquid discharged into the storage space of the shell, a second discharge unit for discharging the cleaning liquid that has passed through the outer portion of the shell, and a particle measuring unit for measuring the particles of the cleaning liquid discharged by the first discharge unit. A control unit that controls the first discharge unit and the particle measurement unit, Equipped with The control unit controls the following: when a first predetermined time has elapsed since the start of cleaning the shell, it switches the cleaning liquid discharged from the first discharge unit from the two fluids to the one fluid; and when a second predetermined time has elapsed since the switch to the one fluid, it controls the particle measurement unit to start measurement. ru. [Effects of the Invention]

[0007] According to embodiments of the present invention, it is possible to detect information regarding particles indicating the degree of cleanliness within the storage space of a cleaned wafer storage container. [Brief explanation of the drawing]

[0008] [Figure 1] Figure 1 is a plan view showing an example of a schematic configuration of a wafer storage container cleaning apparatus according to an embodiment. [Figure 2] Figure 2 is a schematic diagram showing an example of the configuration of a washing tank according to the embodiment. [Figure 3] Figure 3 is a schematic diagram showing an example of the configuration of a washing tank according to the embodiment. [Figure 4] Figure 4 shows an example of the configuration of the control unit according to the embodiment. [Figure 5] Figure 5 is a diagram illustrating an example of the configuration of each part provided in the flow path through which the cleaning fluid flows, downstream of the first discharge section according to the embodiment. [Figure 6] Figure 6 is a flowchart showing an example of the process performed by the wafer storage container cleaning apparatus according to this embodiment. [Figure 7] Figure 7 shows an example of the configuration of a waste liquid measurement tank according to a fourth modified embodiment. [Figure 8] Figure 8 is a diagram illustrating other variations. [Modes for carrying out the invention]

[0009] Hereinafter, embodiments of the wafer storage container cleaning apparatus disclosed in this application will be described in detail with reference to the attached drawings. However, the wafer storage container cleaning apparatus disclosed in this application is not limited to the following embodiments. Furthermore, each embodiment and each modification can be appropriately combined to the extent that no inconsistencies arise. In the following embodiments, the case in which the wafer storage container to be cleaned is a FOUP will be described, but the wafer storage container to be cleaned is not limited to this. For example, the wafer storage container to be cleaned may be an FOSB.

[0010] (Embodiment) Figure 1 is a plan view showing an example of the schematic configuration of a wafer storage container cleaning apparatus 1 according to an embodiment. The wafer storage container cleaning apparatus 1 is installed, for example, in a factory that manufactures semiconductor wafers and cleans wafer storage containers. As shown in Figure 1, the wafer storage container cleaning apparatus 1 includes a load port 2, a robot 3, a disassembly / connection stage 4, a cleaning tank 5, an unload port 6, and a control unit 7.

[0011] The robot 3, disassembly / combination stage 4, cleaning tank 5, and control unit 7 are located inside the casing 1a of the wafer storage container cleaning device 1. On the other hand, the load port 2 and unload port 6 are located across both the inside and outside of the casing 1a of the wafer storage container cleaning device 1.

[0012] Load port 2 loads the FOUP 20 to be cleaned, which is placed on the external part of casing 1a of load port 2, into the interior of casing 1a. The FOUP 20 comprises a shell (FOUP body) 20a and a door (lid) 20b. The shell 20a has an opening (shell opening) and a storage space for housing semiconductor wafers. The storage space is located inside the shell opening and communicates with the shell opening. The door 20b is provided in a manner that allows it to be opened and closed relative to the shell opening. A flange 20c is also provided on the upper part of the shell 20a. The flange 20c is the part that is gripped (held) when the FOUP 20 is transported by an OHT (Overhead Hoist Transport) or robot 3, etc. Note that the OHT may also hold the bottom surface of the FOUP 20 in addition to the flange 20c.

[0013] For example, the FOUP 20, which has been transported with its flange 20c gripped by the OHT, is placed on the outer part of the casing 1a of the load port 2. For example, as shown in Figure 1, the FOUP 20 is placed so that its door 20b faces the casing 1a. When the FOUP 20 is placed on the load port 2 in this way, the shutter 2a provided at the opening 1b of the casing 1a rises. This makes it possible to load the FOUP 20 into the interior of the casing 1a from the opening 1b. That is, the FOUP 20 becomes ready to be loaded into the wafer storage container cleaning device 1. Then, the FOUP 20 is slid in the direction indicated by the arrow 2b by the slide device of the load port 2, and the FOUP 20 is loaded into the interior of the casing 1a. The sliding by the slide device will now be explained. For example, the mounting surface of the FOUP 20 is fixed to the slide device by inserting a pin provided in the slide device into a hole provided in the bottom (mounting surface) of the FOUP 20. In this state, the slide device slides in the direction of arrow 2b, causing the FOUP 20 to slide along with it. As a result, the FOUP 20 is placed on a predetermined part inside the casing 1a of the load port 2. Once the FOUP 20 is brought inside the casing 1a in this way, the shutter 2a descends, closing the opening 1b of the casing 1a. The slide device, along with the pin, descends to a position lower than the lower end of the descended shutter 2a (the mounting surface of the FOUP 20) and returns to its original position outside the casing 1a.

[0014] Robot 3 transports the FOUP 20 to various parts while gripping the flange 20c of the FOUP 20. Robot 3 is equipped with a robot arm 3a and a robot hand 3b. With the flange 20c gripped by the robot hand 3b, Robot 3 transports the FOUP 20 to various parts by extending and retracting or rotating the robot arm 3a.

[0015] The disassembling / connecting stage 4 disassembles the FOUP 20 into the shell 20a and the door 20b, or connects (attaches) the shell 20a and the door 20b. A latch key 4a is provided on the disassembling / connecting stage 4. By rotating the latch key 4a while it is inserted into a latch hole provided in the door 20b of the FOUP 20, the FOUP 20 is disassembled (separated) into the shell 20a and the door 20b, or the shell 20a and the door 20b are connected.

[0016] The cleaning tank 5 is a tank for cleaning the FOUP 20. The cleaning tank 5 is an example of a cleaning unit. FIGS. 2 and 3 are diagrams schematically showing an example of the configuration of the cleaning tank 5 according to the embodiment. Note that FIG. 3 is a schematic plan view of the cleaning tank 5, showing a state in which the FOUP 20 is not placed in the cleaning space. As shown in FIG. 2, for example, the cleaning tank 5 includes a cleaning tank body 5a, a lid portion 5b, a placement portion 5c, a first supply portion (first discharge portion) 5d, a second supply portion (second discharge portion) 5e, a drying portion 5f, a first discharge portion 5g, and a second discharge portion 5h.

[0017] The cleaning tank body 5a has an opening (main body opening) upward and a cleaning space communicating with the main body opening. The cleaning space is a space existing inside the main body opening. The shell 20a is carried into the cleaning space through the main body opening by the robot 3. In this way, the shell 20a is carried into the inside of the cleaning tank body 5a. Then, the carried-in shell 20a is placed on the placement portion 5c provided in the cleaning space of the cleaning tank body 5a. The placement portion 5c is a table (placement table) for placing the shell 20a with the shell opening of the shell 20a facing downward as shown in FIG. 2. As shown in FIG. 3, positioning pins 5r are provided on the placement portion 5c. The placement position of the shell 20a is determined by the positioning pins 5r. As shown in FIGS. 2 and 3, a plurality of through holes 5c_1 are formed in the placement portion 5c. The through holes 5c_1 communicate (connect) with the first discharge portion 5g.

[0018] The lid 5b is located above the cleaning tank body 5a and opens and closes relative to the opening of the cleaning tank body 5a when an air cylinder is operated. Inside the lid 5b, there is a holding part (holding mechanism) 5i that is capable of suctioning and holding the door 20b.

[0019] In this embodiment, when the FOUP 20 is cleaned in the cleaning tank 5, the robot 3 transports the shell 20a and door 20b on the disassembly / connection stage 4 separately to the cleaning tank 5. For example, the robot 3 transports the shell 20a into the interior of the cleaning tank body 5a through the opening of the cleaning tank body 5a with the opening of the shell 20a facing downwards. Then, as shown in Figure 2, the shell 20a is placed on the mounting section 5c with the opening of the shell 20a facing downwards. The robot 3 also transports the door 20b to the holding section 5i so that the outer surface of the door 20b is held by the holding section 5i of the lid section 5b. As a result, as shown in Figure 2, when the lid section 5b is closed, the inner surface (inner surface) of the door 20b faces downwards.

[0020] When the cleaning of the FOUP 20 is completed in the cleaning tank 5, the robot 3 transports the shell 20a and door 20b separately to the disassembly / connection stage 4. The disassembly / connection stage 4 then connects the shell 20a and door 20b.

[0021] Furthermore, a first supply unit 5d and a second supply unit 5e are provided in the cleaning space of the cleaning tank body 5a. The first supply unit 5d and the second supply unit 5e are supplied with a cleaning solution (for example, pure water such as DI water (deionized water)) used when cleaning the shell 20a and the door 20b. The first supply unit 5d cleans the storage space of the shell 20a by supplying (discharging) the cleaning solution into the storage space. The second supply unit 5e cleans the outer part of the shell 20a and the inner surface of the door 20b, which is held by the holding part 5i of the lid 5b, by supplying (discharging) the cleaning solution into the outer part of the shell 20a and the inner surface of the door 20b.

[0022] The first supply unit 5d is positioned to supply cleaning fluid to the storage space of the shell 20a placed on the mounting unit 5c. For example, the first supply unit 5d includes at least one rod-shaped pipe (in this embodiment, two are provided as shown in Figure 3) extending upward from the surface on which the shell 20a is placed on the mounting unit 5c, at least one rod-shaped pipe (not shown in Figure 3) extending horizontally, and a plurality of nozzles 5m provided on each pipe. The nozzles 5m are, for example, two-fluid nozzles. When the nozzles 5m are two-fluid nozzles, they mix air (an example of a gas) and cleaning fluid, atomize the cleaning fluid with the airflow, and supply the atomized cleaning fluid to the storage space of the shell 20a. However, such nozzles 5m can supply cleaning fluid to the storage space without mixing air and cleaning fluid. That is, the nozzles 5m can supply unatomized cleaning fluid to the storage space without atomizing the cleaning fluid.

[0023] The second supply unit 5e is positioned to supply cleaning fluid to the outer portion of the shell 20a and the inner surface of the door 20b. For example, the second supply unit 5e includes at least one rod-shaped pipe extending vertically (in this embodiment, two are provided as shown in Figure 3), a plurality of rod-shaped pipes extending horizontally and rotatable, and a plurality of nozzles 5o or nozzles 5n provided on each pipe. The nozzle 5n is, for example, a two-fluid nozzle similar to the nozzle 5m, provided to discharge toward the door 20b. When the nozzle 5n is a two-fluid nozzle, the nozzle 5n supplies atomized cleaning fluid to the outer portion of the shell 20a and the inner surface of the door 20b. The nozzle 5o is, for example, a one-fluid nozzle. When the nozzle 5o is a one-fluid nozzle, the nozzle 5o supplies cleaning fluid to the outer portion of the shell 20a.

[0024] For example, in Figure 2, the nozzle of the second supply unit 5e, which is positioned between the shell 20a and the door 20b, is retracted to a position that does not interfere with the shell 20a (retracted position) when the shell 20a is being unloaded, loaded, and dried, as shown in Figure 3. After the shell 20a is loaded into the washing space and the lid 5b is closed with the door 20b held in place by the holding unit 5i, the nozzle of the second supply unit 5e rotates to a position above the shell 20a placed on the mounting unit 5c and below the door 20b held by the holding unit 5i (washing position). When washing is complete, it rotates back to the retracted position.

[0025] The drying section 5f is positioned to supply hot air (hot blow) to the storage space of the shell 20a, the outer part of the shell 20a, and the inner surface of the door 20b. For example, the drying section 5f includes at least one rod-shaped pipe extending vertically, at least one rod-shaped pipe extending horizontally, and a plurality of hot blow nozzles provided on each pipe. In this embodiment, when the shell 20a is placed, there are two vertically extending pipes and one horizontally extending pipe that supply hot air to the storage space of the shell 20a. In addition, there are two vertically extending pipes and one horizontally extending, rotatable pipe that supply hot air to the outer part of the shell 20a. The hot blow nozzles provided on these pipes supply hot air to the storage space of the shell 20a, the outer part of the shell 20a, and the inner surface of the door 20b.

[0026] For example, in Figure 2, the drying unit 5f, positioned between the shell 20a and the door 20b, is retracted to a position that does not interfere with the shell 20a (retracted position) when the shell 20a is being removed, brought in, or cleaned, as shown in Figure 3. When cleaning is complete, it rotates to a position above the shell 20a placed on the mounting unit 5c and below the door 20b held by the holding unit 5i (drying position). When drying is complete, it rotates back to the retracted position.

[0027] Furthermore, the cleaning tank body 5a is equipped with a first rotating part including a motor 5k. The first rotating part rotates the mounting part 5c around a vertically extending shaft 5l as its axis of rotation during cleaning and hot blowing of the shell 20a. As the mounting part 5c rotates, the shell 20a mounted on the mounting part 5c also rotates. Furthermore, the lid part 5b is equipped with a second rotating part including a motor 5j. The second rotating part rotates the holding part 5i around a shaft 5l as its axis of rotation during cleaning and drying of the door 20b. As the holding part 5i rotates, the door 20b held by the holding part 5i also rotates. Therefore, during cleaning of the FOUP 20, cleaning fluid is supplied evenly to the FOUP 20. Also, during drying of the FOUP 20, hot blow is supplied evenly to the FOUP 20. Alternatively, the liquid adhering to the shell 20a and door 20b may be dried by rotation by the first and second rotating parts, without supplying hot air from the hot air nozzle.

[0028] The first discharge section 5g discharges the cleaning fluid supplied (discharged) into the storage space of the shell 20a. As described above, the first discharge section 5g is in communication (connected) to the through hole 5c_1. Therefore, the cleaning fluid supplied into the storage space of the shell 20a flows into the first discharge section 5g via the through hole 5c_1. A particle counter 38, described later, is provided in the flow path of the cleaning fluid downstream of the first discharge section 5g.

[0029] The second discharge section 5h discharges the cleaning fluid that has passed over the outside of the shell 20a. The cleaning fluid that has passed over the outside of the shell 20a is the cleaning fluid supplied (discharged) to the outer part of the shell 20a and the inner surface of the door 20b. For example, the second discharge section 5h is an outlet provided at the bottom of the cleaning tank body 5a.

[0030] Returning to the explanation of Figure 1, the unload port 6 transports the cleaned FOUP 20, which has been placed inside the casing 1a of the unload port 6 by the robot 3, to the outside of the casing 1a.

[0031] For example, after cleaning, the FOUP 20, with its shell 20a and door 20b connected in the disassembly / connection stage 4, is transported and placed inside the casing 1a of the unload port 6 by the robot 3. When the FOUP 20 is placed in the unload port 6 in this way, the shutter 6a provided at the opening 1c of the casing 1a rises. This makes the FOUP 20 ready to be transported out of the casing 1a through the opening 1c. In other words, the FOUP 20 is ready to be transported out of the wafer storage container cleaning device 1. Then, the FOUP 20 is slid in the direction indicated by the arrow 6b by the sliding device of the unload port 6 (which has a mechanism similar to the sliding device of the load port 2), and the FOUP 20 is transported out of the casing 1a. Once the FOUP 20 has been transported out of the casing 1a in this way, the shutter 6a descends, and the opening 1c of the casing 1a is closed.

[0032] The control unit 7 controls the operation of the entire wafer storage container cleaning apparatus 1. For example, the control unit 7 controls the load port 2, robot 3, disassembly / combination stage 4, cleaning tank 5, and unload port 6, thereby operating the load port 2, robot 3, disassembly / combination stage 4, cleaning tank 5, and unload port 6 as described above.

[0033] Figure 4 shows an example of the configuration of the control unit 7 according to the embodiment. As shown in Figure 4, the control unit 7 includes a CPU (Central Processing Unit) 7a, a ROM (Read Only Memory) 7b, a RAM (Random Access Memory) 7c, an HDD (Hard Disk Drive) 7d, and a communication interface 7e. These are connected via an internal bus.

[0034] The CPU 7a executes various processes while using the memory area of ​​RAM 7c as a temporary storage area for data used in various processes. The processes executed by CPU 7a will be described later. ROM 7b and HDD 7d store programs for executing various processes, as well as various databases and tables used when executing these processes.

[0035] The communication interface 7e is an interface for communicating with the aforementioned parts of the wafer storage container cleaning apparatus 1, as well as for communicating with external devices connected to the wafer storage container cleaning apparatus 1 via a network. For example, the communication interface 7e is a network interface card.

[0036] Next, an example of the configuration of each part provided in the flow path through which the cleaning liquid flows, downstream of the first discharge section 5g of the wafer storage container cleaning apparatus 1, will be described. Figure 5 is a diagram illustrating an example of the configuration of each part provided in the flow path through which the cleaning liquid flows, downstream of the first discharge section 5g, according to the embodiment.

[0037] As shown in Figure 5, the flow path of the cleaning liquid downstream of the first discharge section 5g is equipped with a three-way valve 31, a waste liquid measurement tank 32, AO valves (air-operated valves) 33-36, a pump 37, a particle counter 38, and liquid level sensors 39, 40. In the following description, AO valve 33 may be referred to as the first AO valve 33, AO valve 34 as the second AO valve 34, AO valve 35 as the third AO valve 35, and AO valve 36 as the fourth AO valve 36.

[0038] The three connection ports of the three-way valve 31 are connected to the first discharge section 5g, the waste liquid side (left side in Figure 5), and the waste liquid measurement tank 32. For example, the cleaning liquid discharged from the first discharge section 5g flows into the three-way valve 31 as waste liquid. The three-way valve 31 is then controlled by the control unit 7, and the waste liquid that has flowed into the three-way valve 31 flows out to either the waste liquid side or the waste liquid measurement tank 32.

[0039] The waste liquid measurement tank 32 stores waste liquid containing particles measured by the particle counter 38.

[0040] The first AO valve 33 is located in the flow path through which pure water flows toward the waste liquid measurement tank 32. When the first AO valve 33 is opened, pure water is supplied to the waste liquid measurement tank 32. When the first AO valve 33 is closed, the supply of pure water to the waste liquid measurement tank 32 is stopped.

[0041] The second AO valve 34 is located in the flow path through which waste liquid flows out of the waste liquid measurement tank 32. When the second AO valve 34 is opened, waste liquid flows out of the waste liquid measurement tank 32. When the second AO valve 34 is closed, the outflow of waste liquid from the waste liquid measurement tank 32 is stopped.

[0042] The third AO valve 35 is located in the flow path through which waste liquid flows from the waste liquid measurement tank 32 to the particle counter 38. When the third AO valve 35 is opened, waste liquid from the waste liquid measurement tank 32 is supplied to the particle counter 38. When the third AO valve 35 is closed, the supply of waste liquid to the particle counter 38 is stopped.

[0043] The fourth AO valve 36 is located in the flow path through which pure water flows toward the particle counter 38. When the fourth AO valve 36 is opened, pure water is supplied to the particle counter 38 and its flow path (measurement line). When the fourth AO valve 36 is closed, the supply of pure water to the particle counter 38 and its flow path (measurement line) is stopped.

[0044] Pump 37 draws in waste liquid or pure water when it operates.

[0045] The particle counter 38 measures the number of particles contained in the supplied waste liquid and outputs information about the particles. For example, the particle counter 38 measures the number of particles contained in a predetermined unit volume (e.g., 10 ml) of waste liquid. The particle counter 38 then outputs the number of particles contained in the predetermined unit volume of waste liquid to the control unit 7 as information about the particles. The particle counter 38 is an example of a particle measurement unit.

[0046] The liquid level sensor 39 is positioned higher than the liquid level sensor 40 and detects whether the liquid level of the waste liquid stored in the waste liquid measurement tank 32 has reached the same height 39a as the liquid level sensor 39. The liquid level sensor 39 performs this detection at predetermined intervals. The liquid level sensor 39 then outputs the detection result to the control unit 7 at predetermined intervals.

[0047] The liquid level sensor 40 detects whether the liquid level of the waste liquid stored in the waste liquid measurement tank 32 has reached the same height 40a as the liquid level sensor 40. The liquid level sensor 40 performs this detection at predetermined intervals. The liquid level sensor 40 then outputs the detection result to the control unit 7 at predetermined intervals.

[0048] Next, an example of the process performed by the wafer storage container cleaning apparatus 1 will be described. Figure 6 is a flowchart showing an example of the flow of the process (operation of the wafer storage container cleaning apparatus 1) performed by the wafer storage container cleaning apparatus 1 according to the embodiment. The process shown in Figure 6 is performed when the FOUP 20 is cleaned in the cleaning tank 5. Note that, for each part other than the control unit 7, the process shown in Figure 6 is performed under the control of the control unit 7.

[0049] The cleaning tank 5 starts cleaning the FOUP 20. At this time, the nozzle 5m of the first supply unit 5d supplies, for example, atomized cleaning liquid (two fluids) into the storage space of the shell 20a (step S101). At the same time, the three-way valve 31 discharges the waste liquid from the first discharge unit 5g to the waste liquid side.

[0050] Next, the CPU 7a of the control unit 7 determines whether a first predetermined time has elapsed since the cleaning of the FOUP 20 was started (the supply of the two-fluid cleaning solution was started) (step S102). This first predetermined time is, for example, the time required for one cleaning of the FOUP 20 by the cleaning tank 5 (cleaning time).

[0051] If the first predetermined time has not elapsed since the start of cleaning the FOUP20 (step S102: No), the supply of cleaning fluid continues, and the CPU7a makes the determination in step S102 again. On the other hand, if the first predetermined time has elapsed since the start of cleaning the FOUP20 (step S102: Yes), the nozzle 5m of the first supply unit 5d starts supplying unatomized cleaning fluid (pure water) to the storage space without mixing air and cleaning fluid (step S103). In other words, in step S103, the nozzle 5m switches the fluid discharged from the nozzle 5m from two fluids, air and cleaning fluid, to pure water (one fluid).

[0052] Next, CPU 7a determines whether a second predetermined time has elapsed since switching to pure water in step S103 (step S104). This second predetermined time is, for example, enough time for all two fluids to be discharged from the storage space.

[0053] If the second predetermined time has not elapsed since switching to pure water (step S104: No), the supply of the single-fluid cleaning solution (single-fluid cleaning solution) continues, and the CPU 7a makes the determination in step S104 again. On the other hand, if the second predetermined time has elapsed since switching to pure water (step S104: Yes), the CPU 7a switches the three-way valve 31 so that the waste liquid (pure water, which is the single-fluid cleaning solution) that has flowed into the three-way valve 31 flows out into the waste liquid measurement tank 32 (step S105). That is, the CPU 7a controls the three-way valve 31 so that the waste liquid flows out into the waste liquid measurement tank 32. At this time, the first AO valve 33, the second AO valve 34, and the third AO valve 35 are closed, and the fourth AO valve 36 is open. Also, the pump 37 starts operating at the timing when the two-fluid cleaning solution is supplied to the storage space in step S101, and pure water is being supplied to the particle counter 38. This is a process to clean the particle measurement area before measurement by the particle counter 38 begins.

[0054] Then, the CPU 7a determines, based on the detection results output from the liquid level sensor 39 at predetermined intervals, whether or not the waste liquid has accumulated in the waste liquid measurement tank 32 to the same height 39a as the liquid level sensor 39 (step S106).

[0055] If the waste liquid has not accumulated to the same height 39a as the liquid level sensor 39 (step S106: No), the waste liquid continues to flow into the waste liquid measurement tank 32, and the CPU 7a performs the determination in step S106 again. On the other hand, if the waste liquid has accumulated to the same height 39a as the liquid level sensor 39 (step S106: Yes), the CPU 7a switches the three-way valve 31 so that the waste liquid that has flowed into the three-way valve 31 flows out to the waste liquid side (step S107). In other words, the CPU 7a controls the three-way valve 31 so that the waste liquid flows out to the waste liquid side.

[0056] Next, CPU 7a stops the pump 37, closes the fourth AO valve 36, and opens the third AO valve 35 (step S108).

[0057] Next, the CPU 7a operates the pump 37 to send the waste liquid in the waste liquid measurement tank 32 to the particle counter 38 (step S109).

[0058] Next, the particle counter 38 measures the number of particles contained in a predetermined unit volume of waste liquid and outputs the number of particles contained in the predetermined unit volume of waste liquid to the control unit 7 as information about the particles (step S110). The particle counter 38 may perform such measurements multiple times and output the average value of multiple measurement results (number of particles contained in a predetermined unit volume of waste liquid) to the control unit 7 as the final measurement result. For example, the particle counter 38 may measure the delivered waste liquid multiple times at predetermined intervals and output the average value of these measurement results to the control unit 7. Alternatively, the storage of waste liquid in the waste liquid measurement tank 32 and measurement by the particle counter 38 may be repeated multiple times, and the average value of the results measured multiple times by the particle counter 38 may be output to the control unit 7. In this case, accurate measurement can be achieved by inserting the steps of discharging the waste liquid from the waste liquid measurement tank 32 in step S115, storing pure water in the waste liquid measurement tank in step S116, and discharging the pure water from the waste liquid measurement tank in step S117, which will be described later.

[0059] Next, the CPU 7a generates information that associates the measurement results with the ID (individual identification number) of the FOUP 20, stores the generated information in the HDD 7d, and controls the communication interface 7e to output it to an external device that centrally manages all FOUPs in the factory (step S111). For example, the control unit 7 is equipped with an ID reading unit, which reads the ID (Identification) of the FOUP 20, which is the identification information of the FOUP 20, provided on the FOUP 20. The ID reading unit is just one example of a reading unit. For example, the ID of the FOUP 20 can be obtained by a barcode scanner (barcode reader), which is the ID reading unit. For example, the barcode scanner reads the barcode that shows the individual identification number of the FOUP 20 as the ID of the FOUP 20, and transmits the individual identification number shown by the read barcode to the CPU 7a. Alternatively, for example, the ID reading unit may be a reader that reads the individual identification number of the FOUP 20 output as the ID of the FOUP 20 from an RF tag provided on the FOUP 20. In this case, the reader transmits the read individual identification number to the CPU 7a. Alternatively, instead of outputting the particle measurement results to an external device that centrally manages all FOUPs in the factory, the measurement result information may be written to an RF tag provided on the FOUP 20.

[0060] As a result of the processing in step S111, the communication interface 7e outputs information about the particles measured by the particle counter 38. The communication interface 7e is an example of an output unit. Also, as a result of the processing in step S111, the HDD 7d stores a history of information about the particles associated with FOUP20 (more specifically, the ID of FOUP20).

[0061] Next, CPU 7a stops the pump 37, closes the third AO valve 35, and opens the fourth AO valve 36 (step S112).

[0062] Next, the CPU 7a operates the pump 37 to supply pure water to the particle counter 38 and its flow path, thereby purging the flow path (step S113).

[0063] Next, the CPU 7a opens the second AO valve 34 to discharge the waste liquid remaining in the waste liquid measurement tank 32 (step S114).

[0064] Next, the CPU 7a determines whether all of the waste liquid remaining in the waste liquid measurement tank 32 has been discharged from the waste liquid measurement tank 32 (step S115). For example, based on the detection results output from the liquid level sensor 40 at predetermined intervals, the CPU 7a determines that all of the waste liquid remaining in the waste liquid measurement tank 32 has been discharged from the waste liquid measurement tank 32 if a predetermined time has elapsed since the liquid level of the waste liquid reached the same height 40a as the liquid level sensor 40. On the other hand, if this is not the case, the CPU 7a determines that all of the waste liquid remaining in the waste liquid measurement tank 32 has not been discharged from the waste liquid measurement tank 32.

[0065] If the waste liquid remaining in the waste liquid measurement tank 32 has not been completely discharged from the waste liquid measurement tank 32 (step S115: No), the discharge of the waste liquid continues, and the CPU 7a makes the determination in step S115 again. On the other hand, if the waste liquid remaining in the waste liquid measurement tank 32 has been completely discharged from the waste liquid measurement tank 32 (step S115: Yes), the CPU 7a opens the first AO valve 33 and closes the second AO valve 34 (step S116). As a result, pure water is supplied to the waste liquid measurement tank 32, and pure water is stored in the waste liquid measurement tank 32. In step S116, the waste liquid measurement tank 32 stores pure water until it overflows. The time required until overflow is determined in advance, and pure water should be continuously supplied to the waste liquid measurement tank 32 for this time.

[0066] Next, CPU 7a closes the first AO valve 33 and opens the second AO valve 34 (step S117). This causes the pure water in the waste liquid measurement tank 32 to be discharged from the waste liquid measurement tank 32.

[0067] Next, the CPU 7a determines whether the process in steps S116 and S117 has been repeated a predetermined number of times (step S118). When the process in steps S116 and S117 is repeated a predetermined number of times, the waste liquid measurement tank 32 is purged.

[0068] If the processes in steps S116 and S117 have not been repeated a predetermined number of times (step S118: No), the CPU 7a returns to step S116 and performs each of the processes from step S116 onward again. On the other hand, if the processes in steps S116 and S117 have been repeated a predetermined number of times (step S118: Yes), the CPU 7a terminates the process shown in Figure 6.

[0069] The wafer storage container cleaning apparatus 1 according to the embodiment has been described above. As described above, the wafer storage container cleaning apparatus 1 cleans a FOUP 20 which has a shell 20a having a shell opening and a storage space for storing semiconductor wafers that is in communication with the shell opening, and a door 20b that is attached to the shell opening so as to be openable and closable. Such a wafer storage container cleaning apparatus 1 comprises a cleaning tank body 5a having a main body opening and a cleaning space communicating with the main body opening; a lid portion 5b that can be opened and closed relative to the main body opening; a mounting portion 5c provided in the cleaning space, on which a shell 20a is placed facing the shell opening, and on which a through hole 5c_1 communicating with the storage space is formed in the portion facing the shell opening; a first supply portion 5d that supplies cleaning liquid to the storage space of the shell 20a; a second supply portion 5e that supplies cleaning liquid to the outer portion of the shell 20a; a first discharge portion 5g that communicates with the through hole 5c_1 and discharges the cleaning liquid supplied to the storage space of the shell 20a; a second discharge portion 5h that discharges the cleaning liquid that has passed through the outer portion of the shell 20a; and a particle counter 38 that measures the particles of the cleaning liquid discharged by the first discharge portion 5g.

[0070] In this way, the cleaning solution supplied to the storage space of the shell 20a and the cleaning solution that has passed through the outer part of the shell 20a are separated and discharged as waste liquid. Therefore, only the cleaning solution supplied to the storage space of the shell 20a can be supplied to the particle counter 38. Accordingly, according to the wafer storage container cleaning apparatus 1 of this embodiment, it is possible to detect information regarding particles indicating the degree of cleanliness in the storage space of the cleaned FOUP 20.

[0071] (First modified example of the embodiment) Next, a wafer storage container cleaning apparatus 1 according to the first modification of the embodiment will be described. The wafer storage container cleaning apparatus 1 according to the first modification differs from the wafer storage container cleaning apparatus 1 according to the embodiment in that it additionally cleans the FOUP 20 when the number of particles contained in a predetermined unit volume of waste liquid measured by the particle counter 38 is greater than or equal to a predetermined value.

[0072] In the first modified example, after the cleaning of the FOUP 20 has started and the first predetermined time described above has elapsed, the CPU 7a of the control unit 7 determines whether the number of particles contained in a predetermined unit volume of waste liquid is equal to or greater than a predetermined value. The first predetermined time is, as described above, for example, the cleaning time required for one cleaning of the FOUP 20 by the cleaning tank 5.

[0073] If the number of particles in a predetermined unit volume of waste liquid is less than a predetermined value, the CPU 7a controls the cleaning tank 5 to complete the cleaning. On the other hand, if the number of particles in a predetermined unit volume of waste liquid is greater than or equal to the predetermined value, the CPU 7a controls the cleaning tank 5 to clean the FOUP 20 for an additional cleaning time. After the additional cleaning time has elapsed since the additional cleaning of the FOUP 20 began, the particle counter 38 measures the number of particles in the predetermined unit volume of waste liquid again. The CPU 7a then determines again whether the number of particles in the predetermined unit volume of waste liquid is greater than or equal to the predetermined value. The CPU 7a then repeats the same process as described above until the number of particles in the predetermined unit volume of waste liquid falls below the predetermined value. If the number of times the CPU 7a determines that the number of particles in the predetermined unit volume of waste liquid is greater than or equal to the predetermined value reaches a predetermined number of times, it may control the unload port 6 to terminate the cleaning and discharge the FOUP 20 as a defective product. Furthermore, if the ratio of the number of FOUP20s that need to be cleaned per unit time exceeds a certain percentage (for example, 10%), the CPU 7a may change the first predetermined time to a new first predetermined time that includes the additional cleaning time. The additional cleaning time may be constant, but the CPU 7a may also vary the additional cleaning time according to the percentage. For example, the CPU 7a may be set so that the additional cleaning time increases as the percentage exceeds the limit.

[0074] In the first modified example, the CPU 7a may determine the additional cleaning time based on the number of particles contained in a predetermined unit volume of waste liquid. For example, the CPU 7a may determine the additional cleaning time to be longer as the number of particles contained in a predetermined unit volume of waste liquid increases.

[0075] The wafer storage container cleaning apparatus 1 according to the first modification has been described above. In the first modification, the control unit 7 controls the FOUP 20 to be cleaned additionally if the number of particles measured by the particle counter 38 is greater than or equal to a predetermined value after the FOUP 20 has been cleaned for a first predetermined time (predetermined cleaning time).

[0076] According to the first modified wafer storage container cleaning apparatus 1, if the cleaning of the FOUP 20 is insufficient, additional cleaning is performed, so that the degree of cleanliness of the FOUP 20 can be provided that meets the standard.

[0077] (Second modified example of the embodiment) Next, a wafer storage container cleaning apparatus 1 according to a second modification of the embodiment will be described. In the wafer storage container cleaning apparatus 1 according to the second modification, the waste liquid discharged from the first discharge unit 5g is sent to the particle counter 38 without being stored in the waste liquid measurement tank 32, and the number of particles contained in a predetermined unit volume of waste liquid is measured. The wafer storage container cleaning apparatus 1 then continues to clean the FOUP 20 until the number of particles contained in a predetermined unit volume of waste liquid falls below a predetermined value. The wafer storage container cleaning apparatus 1 terminates cleaning when the number of particles falls below the predetermined value. Therefore, according to the wafer storage container cleaning apparatus 1 according to the second modification, it is possible to provide a FOUP 20 whose degree of cleanliness meets the standard, similar to the first modification. In the second modification, the two-fluid cleaning solution used for cleaning may be sent directly to the particle counter 38, or the cleaning solution may be switched from two fluids to one fluid at a predetermined timing, and the measurement by the particle counter 38 may be performed at a predetermined time after the switch to one fluid.

[0078] Furthermore, depending on the cleanliness (contamination level) of the FOUP 20, the cleaning time may be shorter than the first predetermined time described above. In the second modification, the waste liquid is not stored in the waste liquid measurement tank 32 but is sent to the particle counter 38, and the control unit 7 controls the cleaning of the FOUP 20 to be completed according to the particle information measured by the particle counter 38. Therefore, the FOUP 20 can be cleaned efficiently.

[0079] In the second modified example, the waste liquid discharged from the first discharge section 5g may be stored in the waste liquid measurement tank 32 while being sent to the particle counter 38.

[0080] Alternatively, an upper limit for the cleaning time may be set in advance. If the number of particles contained in a predetermined unit volume of waste liquid remains above a predetermined value while the cleaning time reaches the upper limit, the cleaning of the FOUP20 may be terminated, and the FOUP20 may be discharged as a defective product.

[0081] (Third modified example of the embodiment) Next, a wafer storage container cleaning apparatus 1 according to a third modification of the embodiment will be described. The wafer storage container cleaning apparatus 1 according to the third modification determines the first predetermined time described above based on information about the wafers stored in the FOUP 20. The ID reading unit obtains information about the process used before the FOUP 20 was brought into the wafer storage container cleaning apparatus 1 from the RF tag provided on the FOUP 20. This makes it possible to identify the type of wafer stored in the FOUP 20 (including the type of film formed on the wafer). The time for cleaning the FOUP 20 (first predetermined time) is determined according to the identified type of wafer. Therefore, the FOUP 20 can be cleaned efficiently.

[0082] (Fourth modified example of the embodiment) Next, a wafer storage container cleaning apparatus 1 according to a fourth modification of the embodiment will be described. The wafer storage container cleaning apparatus 1 according to the fourth modification has a waste liquid measurement tank 320 instead of a waste liquid measurement tank 32. The waste liquid measurement tank 320 will be described with reference to Figure 7.

[0083] Figure 7 shows an example of the configuration of a waste liquid measuring tank 320 according to a fourth modification of the embodiment. As shown in Figure 7, the waste liquid measuring tank 320 is equipped with an AO valve 310 in place of the three-way valve 31 and an AO valve 330 in place of the first AO valve 33. An overflow wall 341 and a barrier 321 are provided inside the waste liquid measuring tank 320. The overflow wall 341 is a cylindrical pipe, and its upper end is open into the waste liquid measuring tank 320. The lower end of the overflow wall 341 is connected to the bottom surface of the waste liquid measuring tank 320, and a pipe to which a second AO valve 34 is provided is connected to the bottom surface of the waste liquid measuring tank 320 to which the lower end is connected, so that the lower end of the overflow wall 341 and the pipe to which the second AO valve 34 is provided are in communication. The barrier 321 is a plate-shaped member provided to divide the space inside the waste liquid measurement tank 320 into two sections: one side where the overflow wall 341 is provided, and the other side where the piping leading to the particle counter 38 and the piping for purging the waste liquid measurement tank 320 with pure water are provided. The upper end of the barrier 321 is provided on the ceiling of the waste liquid measurement tank 320, and the lower end is provided in a position that forms a small gap from the bottom surface of the waste liquid measurement tank 320.

[0084] Furthermore, the height at which the piping supplied with wastewater from the first discharge section 5g connects to the wastewater measurement tank 320 is set lower than the upper end of the overflow wall 341. If the height is set far above the bottom surface of the wastewater measurement tank 320, the newly supplied wastewater will fall onto the surface of the wastewater stored in the wastewater measurement tank 320, generating many bubbles in the wastewater. If the wastewater containing bubbles is sent to the particle counter 38, the bubbles will be misdetected as particles, making accurate measurement impossible. Therefore, it is preferable that the height at which the piping supplied with wastewater from the first discharge section 5g connects to the wastewater measurement tank 320 is set close to the bottom surface of the wastewater measurement tank 320.

[0085] Furthermore, the location where the AO valve 330 is installed in the pure water supply piping is connected to the waste liquid measurement tank 320 is, as described above, on the side of the waste liquid measurement tank 320 separated from the third AO valve 35 by the barrier 321. This allows for sufficient purging of the area near the piping that supplies liquid to the particle counter 38. The other structures are the same as in the embodiment described above.

[0086] In step S101 of the above-described embodiment, when the two cleaning fluids are supplied to the storage space, the waste liquid discharged from the first discharge section 5g is supplied into the waste liquid measurement tank 320 via the open AO valve 310. In other words, in the embodiment described above, the supply of waste liquid to the waste liquid measurement tank 32 is started after a first predetermined time has elapsed and a second predetermined time has elapsed. However, in this modified example, all of the supplied cleaning fluid is supplied to the waste liquid measurement tank 320 without waiting for the first and second predetermined times to elapse. The waste liquid supplied into the waste liquid measurement tank 320 is stored in the waste liquid measurement tank 320 and, once it overflows the overflow wall 341, is discharged from the AO valve 34 side. A portion of the waste liquid stored in the waste liquid measurement tank 320 is stored from below the barrier 321 towards the third AO valve 35 side. When the first predetermined time has elapsed (Yes in S102), the cleaning fluid is switched to a single fluid. When the second predetermined time has elapsed (Yes in step S104), the third AO valve 35 is opened, and the pump 37 is activated to perform measurement with the particle counter 38. The second predetermined time here can be set to the amount of time required for the single cleaning fluid supplied to the waste liquid measurement tank 320 after the first predetermined time has elapsed to replace the two cleaning fluids that were supplied before the first predetermined time had elapsed. With the waste liquid measurement tank 320, the waste liquid stored in the upper part of the waste liquid measurement tank 320, which contains many air bubbles, is discharged over the overflow wall 341. Also, the waste liquid stored in the lower part of the waste liquid measurement tank 320, which does not contain many air bubbles, passes through the gap below the barrier 321 and is sent to the particle counter 38. Therefore, it is possible to measure the waste liquid containing air bubbles with the particle counter 38 and prevent the bubbles from being mistakenly detected as particles. Furthermore, by providing an overflow wall 341 in the waste liquid measurement tank 320, and ensuring that all of the waste liquid from the first discharge section 5g is supplied into the waste liquid measurement tank 320, waste liquid is always stored in the waste liquid measurement tank 320, eliminating the need to install liquid level sensors 39 and 40 to measure the amount of stored waste liquid.

[0087] Furthermore, the waste liquid discharged from the first discharge section 5g may be the two fluids used for cleaning, without switching to a single fluid. Since the waste liquid, from which air bubbles have been removed during the process of passing through the overflow wall 341 and barrier 321, is more easily supplied to the particle counter 38, false detections by the particle counter 38 can be prevented even with a two-fluid cleaning solution. In this case, measurements by the particle counter 38 can be performed continuously without waiting for the first predetermined time and the second predetermined time to elapse.

[0088] (Other variations) Next, other modifications will be described. Figure 8 is a diagram illustrating other modifications. For example, bubbles contained in the waste liquid may affect the measurement by the particle counter 38. For this reason, as shown in Figure 8, a degassing unit 50 and a degassing pump 51 may be provided in front of the particle counter 38, and the degassing unit 50 and degassing pump 51 may degas the waste liquid supplied to the particle counter 38. In this case, it is not necessary to control the fluid discharged from the nozzle 5m from two fluids to one fluid before it flows out into the waste liquid measurement tank 32.

[0089] Alternatively, a heater may be provided instead of a hot blow nozzle to dry the FOUP20. Alternatively, both a hot blow nozzle and a heater may be provided.

[0090] Furthermore, the piping that guides the waste liquid supplied from the first discharge section 5g to the waste liquid measurement tank 32 via the three-way valve 31 may be provided to extend close to the bottom of the waste liquid measurement tank 32, similar to the piping that guides the pure water supplied via the first AO valve 33. By supplying waste liquid close to the bottom of the waste liquid measurement tank 32, it is possible to prevent foaming of the waste liquid already stored in the waste liquid measurement tank 32 by supplying new waste liquid to the liquid surface. By preventing foaming of the liquid surface, accurate measurement by the liquid level sensor 39 can be performed, and it is also possible to prevent air bubbles from being contained in the waste liquid sent to the particle counter 38.

[0091] Alternatively, the waste liquid measurement tank 32 may be omitted, and the waste liquid discharged from the first discharge section 5g may flow directly to the particle counter 38.

[0092] Furthermore, a portion of the cleaning solution supplied to the storage space of the shell 20a may flow into the second discharge section 5h. Only the liquid supplied to the storage space of the shell 20a needs to be subject to particle measurement.

[0093] Furthermore, although the case in which the shell 20a and door 20b are cleaned simultaneously in a single cleaning tank 5 has been described, it is also possible to provide two cleaning tanks: one for cleaning the shell 20a and another for cleaning the door 20b.

[0094] Furthermore, in the above-described embodiment, the particle counter 38 is provided in a flow path connected to the side of the waste liquid measurement tank 32 and measures the waste liquid in the flow path, but the system is not limited to this. For example, a tank may be provided downstream of the waste liquid measurement tank 32, and the waste liquid supplied from this tank may be measured by the particle counter 38. In this case, the waste liquid measurement tank 32 or the downstream tank may be made into a sealed structure, and a degassing pump may be connected to the tank so that the waste liquid in the tank is degassed before being supplied to the particle counter 38.

[0095] Furthermore, in the above-described embodiment, it was illustrated that pure water, which is a fluid supplied from nozzle 5m, is collected in waste liquid measurement tank 32 and measured by particle counter 38, but the invention is not limited to this. For example, a dedicated nozzle for supplying fluid (pure water) to be delivered to particle counter 38 may be provided. Alternatively, a nozzle other than the nozzle that discharges the cleaning solution (nozzle 5m) may be provided to supply the fluid used for processing FOUP 20, and the fluid to be delivered to particle counter 38 may be supplied from this nozzle. It is preferable that the fluid from the nozzle is supplied so as to cover the area of ​​the shell 20a where a wafer holding shelf (not shown) is formed.

[0096] Although several embodiments of the present invention have been described above, these embodiments are presented as examples only and are not intended to limit the scope of the invention. These novel embodiments can be implemented in a variety of other forms, and various omissions, substitutions, modifications, and combinations are possible without departing from the spirit of the invention. These embodiments and their variations are included in the scope and spirit of the invention, as well as in the claims of the invention and its equivalents. [Explanation of symbols]

[0097] 1. Wafer storage container cleaning device 5. Washing tank 5a Washing tank body 5b Lid 5c Mounting section 5d First supply unit 5e Second supply section 5g First discharge section 5h Second discharge section 7e communication interface 38 Particle Counter

Claims

1. A wafer storage container cleaning apparatus for cleaning a wafer storage container having a shell having a shell opening and a storage space for storing semiconductor wafers, the storage space being in communication with the shell opening, and a door being attached to the shell opening so as to be openable and closable, A cleaning tank body having a main body opening and a cleaning space communicating with the main body opening, A lid portion is provided that can be opened and closed relative to the opening of the main body, A mounting section is provided within the cleaning space, on which the shell is placed facing the shell opening, and a through hole communicating with the storage space is formed in the portion facing the shell opening, The shell has a first discharge unit that switches between discharging a one-fluid cleaning solution and a two-fluid cleaning solution into the storage space of the shell, The outer portion of the shell is provided with a second discharge section for discharging cleaning fluid, A first discharge section that communicates with the through hole and discharges the cleaning fluid discharged into the storage space of the shell, A second discharge section for discharging the cleaning fluid that has passed through the outer portion of the shell, A particle measuring unit for measuring particles in the cleaning liquid discharged by the first discharge unit, A control unit that controls the first discharge unit and the particle measurement unit, Equipped with, A wafer storage container cleaning apparatus, wherein the control unit controls the cleaning solution discharged from the first discharge unit to be switched from the two fluids to the one fluid after a first predetermined time has elapsed since the start of cleaning the shell, and starts measurement by the particle measurement unit after a second predetermined time has elapsed since the switch to the one fluid.

2. The system further includes a waste liquid measuring tank connected to the first discharge section, The waste liquid measurement tank is connected to the particle measurement unit via an on / off valve. The control unit opens the on / off valve after the second predetermined time has elapsed. A wafer storage container cleaning apparatus according to claim 1.

3. The first discharge section is connected to the waste liquid measurement tank and to a waste liquid flow path separate from the waste liquid measurement tank. The control unit controls the discharge of the cleaning liquid from the first discharge unit into the waste liquid flow path from the start of cleaning the shell until the second predetermined time has elapsed, and after the second predetermined time has elapsed, it controls the discharge of the cleaning liquid from the first discharge unit into the waste liquid measuring tank. The wafer storage container cleaning apparatus according to claim 2.

4. The control unit controls the wafer storage container to be cleaned additionally if, after the wafer storage container has been cleaned for the first predetermined time, the number of particles measured by the particle measurement unit is greater than or equal to a predetermined value. A wafer storage container cleaning apparatus according to any one of claims 1 to 3.

5. The control unit determines the additional cleaning time based on the number of particles. The wafer storage container cleaning apparatus according to claim 4.

6. The control unit includes a control unit that controls the cleaning of the wafer storage container to be completed when the number of particles measured by the particle measurement unit falls below a predetermined value. A wafer storage container cleaning apparatus according to any one of claims 1 to 3.

7. The system includes a control unit that determines the cleaning time of the wafer storage container based on information about the wafers stored in the wafer storage container. A wafer storage container cleaning apparatus according to any one of claims 1 to 3.

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