Flow rate measurement device and flow rate measurement system

Abstract

This flow rate measurement device is connected to at least one air supply nozzle of a purge device and measures the supply flow rate of a purge gas supplied from the purge device. The flow rate measurement device comprises: at least one introduction part that is connected to the air supply nozzle and introduces the purge gas; a primary pipe connected to the introduction part; a flow rate measurement instrument that is provided to the primary pipe and measures the flow rate of the purge gas flowing through the primary pipe; a plurality of secondary pipes that are connected to the downstream side of the primary pipe via a branch part; and a flow path switching unit that switches the flow path of the purge gas to at least any one of the plurality of secondary pipes.

Description

Flow rate measuring device and flow rate measuring system

[0001] This disclosure relates to a flow rate measuring device and a flow rate measuring system.

[0002] A gas supply device is known that supplies a purifying gas (purge gas) into a container that houses a reticle or semiconductor wafer. Such a gas supply device is installed in a storage shelf that houses the container. As described in Patent Document 1, a flow rate measuring device is known that is used for inspecting a gas supply device and for measuring the flow rate of the purifying gas supplied into the container. The flow rate measuring device described in Patent Document 1 comprises a pipe connected to the gas discharge part of the gas supply device, a flow meter for measuring the flow rate of the gas flowing inside the pipe, and a resistor that applies resistance to the gas flow inside the pipe. The resistor in Patent Document 1 is configured so that the magnitude of the resistance applied to the flow path can be adjusted by operating a knob or the like.

[0003] Japanese Patent Publication No. 2018-41925

[0004] For a flow rate measuring device to accurately measure the purge gas flow rate, it is desirable that it be installed in a gas supply device with a flow resistance equivalent to that of the aforementioned container. However, the required resistance varies depending on the type of container and the flow rate of the supplied purge gas. The resistor in Patent Document 1 has an adjustable resistance, but it is very time-consuming to adjust the resistance of the resistor itself to a value corresponding to multiple conditions each time.

[0005] This disclosure describes a flow rate measuring device and a flow rate measuring system that can easily switch the magnitude of the flow path resistance.

[0006] [1] One aspect of the present disclosure is a flow rate measuring device connected to at least one air supply nozzle of a purge device for measuring the supply flow rate of purge gas supplied from the purge device, comprising: at least one inlet connected to the air supply nozzle for introducing purge gas; primary piping connected to the inlet; a flow rate measuring instrument provided in the primary piping for measuring the flow rate of purge gas flowing through the primary piping; a plurality of secondary pipes connected to the downstream side of the primary piping via a branching section; and a flow path switching section for switching the flow path of purge gas to at least one of the plurality of secondary pipes.

[0007] According to the flow rate measuring device in [1], multiple secondary pipes are connected to the primary pipe downstream via a branching section. The flow path switching section switches the flow path of the purge gas to at least one of the multiple secondary pipes. In each of the secondary pipes, multiple different flow path resistances can be set by setting the pipe diameter or installing resistance elements so that the flow path resistance (or pressure loss) when the purge gas flows becomes a desired value. Therefore, according to the flow rate measuring device in [1], the flow path resistance can be easily switched simply by switching the flow path.

[0008] [2] The flow rate measuring device described in [1] above may include a plurality of inlet sections connected to each of the plurality of air supply nozzles for introducing purge gas, and a plurality of primary pipes connected to each of the plurality of inlet sections, with a flow rate measuring instrument provided in each of the plurality of primary pipes. With this configuration, the flow resistance can be appropriately set in each of the plurality of inlet sections. The flow rate in each of the plurality of inlet sections can also be measured. The flow rate difference between one inlet section and another can also be calculated.

[0009] [3] The flow rate measuring device described in [1] or [2] above may be provided in at least one of the multiple secondary pipes and may be equipped with a resistance element having a unique resistance characteristic. With this configuration, by appropriately selecting the resistance element (resistance characteristic), a desired flow path resistance can be set for each of the multiple different flow rates.

[0010] [4] The flow rate measuring device described in [1] or [2] above may be provided in each of the multiple secondary pipes and may be equipped with multiple resistance elements having different inherent resistance characteristics. With this configuration, by appropriately selecting each resistance element (each resistance characteristic), the desired flow path resistance can be reliably set for each of the multiple different flow rates.

[0011] [5] In any one of the flow rate measuring devices described in [1] to [4] above, the flow path switching section may be a three-way valve provided at the branching section. With this configuration, the flow path of the purge gas corresponding to two different flow rates can be easily switched by operating the three-way valve.

[0012] [6] In any one of the flow rate measuring devices described in [1] to [4] above, the flow path switching section may be an on-off valve provided at the branching section. This configuration allows for easy switching of the flow path of the purge gas corresponding to two different flow rates with a simpler configuration.

[0013] [7] In any one of the flow rate measuring devices described in [1] to [6] above, the flow resistance in at least one of the multiple secondary pipes may be set to a size corresponding to the purge gas flow rate supplied by the purge device for each selected air supply mode. This configuration makes it possible to easily switch to a flow resistance suitable for each air supply mode.

[0014] [8] In any one of the flow measuring devices described in [1] to [6] above, the flow resistance in at least one of the multiple secondary pipes may be set to a magnitude corresponding to the resistance generated inside a particular container among the multiple types of containers. With this configuration, it is possible to apply a flow resistance similar to that when gas is supplied to the container, depending on the type of container.

[0015] [9] In another aspect of the present disclosure, a flow rate measuring system may be provided. The flow rate measuring system comprises a purge device having an air supply nozzle, an air supply pipe connected to the air supply nozzle, a pressure gauge attached to the air supply pipe, and a controller provided in the air supply pipe for controlling the supply flow rate of purge gas, and one of the flow rate measuring devices described in [1] to [8] above connected to the air supply nozzle. With this flow rate measuring system, the supply flow rate of purge gas is controlled by the controller. Purge gas can be supplied at a desired flow rate, and a desired flow resistance can be set. In addition, the supply pressure of the purge gas can be confirmed by the pressure gauge.

[0016] According to this disclosure, when purge gas is supplied at multiple different flow rates, it is possible to provide the same flow resistance as when gas is supplied to a container.

[0017] Figure 1 is a diagram showing the overall configuration of a storage shelf to which a flow rate measuring device according to one embodiment of the present disclosure is applied. Figure 2 is a perspective view showing the purge device and storage shelf and the overhead vehicle. Figure 3 is a rear perspective view of the flow rate measuring device according to one embodiment of the present disclosure. Figure 4 is a diagram showing the schematic configuration of the flow rate measuring device of Figure 3. Figure 5 is a diagram showing an example of the time change of flow rate in two types of air supply modes. Figure 6 is a diagram illustrating the flow rate and pressure loss characteristics in the flow paths of two types of purge gases, and the flow rate and pressure loss characteristics in the container. Figure 7(a) is a diagram showing the flow path of the purge gas according to a low flow rate air supply mode, and Figure 7(b) is a diagram showing the flow path of the purge gas according to a high flow rate air supply mode. Figures 8(a) to 8(c) are diagrams showing the schematic configuration of a modified flow rate measuring device, respectively. Figures 9(a) to 9(c) are diagrams showing the schematic configuration of a modified flow rate measuring device, respectively. Figures 10(a) and 10(b) are diagrams showing the schematic configuration of a modified flow rate measuring device, respectively.

[0018] Embodiments of this disclosure will be described below with reference to the drawings. In the description of the drawings, the same elements will be denoted by the same reference numerals, and redundant explanations will be omitted. The terms "X direction," "Y direction," and "Z direction" are based on the directions shown in the illustrations and are for convenience only.

[0019] As shown in Figures 1 and 2, the storage rack 1 is positioned along the track 5 of an overhead transport vehicle 3 that constitutes a semiconductor transport system SA in a semiconductor manufacturing plant, for example. The storage rack 1 temporarily stores containers F such as FOUPs or reticle pods. The storage rack 1 is an overhead buffer (OHB). The storage rack 1 may also be a side track buffer (STB) positioned to the side of the track 5. The storage rack 1 is configured to purge the inside of the containers F with a purge gas (fluid) such as nitrogen.

[0020] As shown in Figure 1, the semiconductor transport system SA comprises a plurality of storage shelves 1 suspended from the ceiling 100, a distribution board 2 that supplies power to the storage shelves 1 via power supply wiring 6, a monitoring stand 4 that monitors the oxygen concentration in the factory, and a gas supply pipe 8 laid on the ceiling 100 that supplies purge gas to each storage shelf 1. Purge gas adjusted to a desired pressure is supplied to the gas supply pipe 8. The distribution board 2 and the monitoring stand 4 are installed, for example, on the floor 9. The distribution board 2 may be provided with an emergency stop button 2a to stop the supply of purge gas to the storage shelves 1 in case of an emergency. The monitoring stand 4 is also equipped with an oxygen concentration sensor 4a. The monitoring stand 4 may be provided with an emergency stop button 4b to stop the supply of purge gas when the oxygen concentration drops.

[0021] As shown in Figures 1 and 2, each storage rack 1 comprises, for example, two base frames 10, 10 suspended from the ceiling 100, and two beam members 14, 14 spanning between the two base frames 10, 10. Each base frame 10 has, for example, two suspension parts 11 suspended from the ceiling 100 and extending in the vertical Z direction, and one support part 12 spanning across the lower ends of the suspension parts 11 and extending in the horizontal Y direction. The Y direction is perpendicular to the X direction, which is the direction in which the overhead transport vehicle 3 travels, and is also horizontal. The Y direction is also the direction of lateral transfer by the overhead transport vehicle 3.

[0022] In each storage rack 1, a flat shelf board 15 is attached to the beam material 14. The shelf board 15 is a plate member that, for example, is approximately the same size as the bottom surface of the container F in a plan view, or slightly smaller in size than the bottom surface of the container F. Notches or openings may be formed in the shelf board 15 (at positions other than the positioning pins 17 and the opening 15e). The shelf board 15 extends horizontally, for example. Three positioning pins 17 are erected on the upper surface 15a of the shelf board 15 for positioning the container F. The three positioning pins 17 are positioned at locations corresponding to the vertices of a triangle and are provided to protrude from the shelf board 15. The three positioning pins 17 support the container F to be purged. The positioning pins 17 are also called kinematic pins.

[0023] The shelf 15 and positioning pins 17 constitute a mounting section 7 on which the container F is placed. The bottom surface of the container F is provided with grooves (not shown) for receiving the positioning pins 17. The mounting section 7 is configured so that the container F can be placed horizontally on it.

[0024] As shown in Figure 1, for example, one gas supply pipe 8 is laid for one storage shelf 1, and four gas distribution pipes 8a corresponding to four mounting sections 7 (purge devices 20) branch off from the one gas supply pipe 8. The pressure gauge 26 detects the presence or absence of containers F in each mounting section 7 of the storage shelf 1. For example, a control device 21 located near the distribution board 2 controls the MFC 23, which will be described later, according to the storage status of one or more containers F in the storage shelf 1 detected by the pressure gauge 26. The control device 21 controls the MFC 23 by wire or wireless means (not shown).

[0025] One storage rack 1 has, for example, four mounting sections 7. A total of four purge devices 20 are attached to the four mounting sections 7. Each purge device 20 is installed for each mounting section 7. As shown in Figures 1, 2, and 4, each purge device 20 comprises the above-mentioned shelf 15, air supply pipes 24A, 24B and air supply nozzles 25A, 25B attached to the shelf 15, a single air supply pipe 22 connected to the upstream side of the air supply pipes 24A, 24B, a pressure gauge 26 attached to the air supply pipe 22, and a mass flow controller (controller; hereinafter referred to as MFC) 23 provided in the air supply pipe 22 and supplying purge gas in an amount according to the command of the control device 21. The air supply pipe 22 is connected to the downstream side of the gas distribution pipe 8a shown in Figure 1.

[0026] The purge device 20 supplies purge gas into the container F through two air supply ports (not shown) formed on the bottom surface of the container F to be purged. The MFC 23 is a control device that controls the flow rate of the purge gas flowing through the air supply pipe 22. Here, if multiple air supply nozzles 25 are connected to one MFC 23, the MFC 23 controls only the total purge gas flow rate of all connected air supply nozzles 25. The flow rate of purge gas discharged (supplied to container F) from each air supply nozzle 25 is distributed according to the pressure loss due to the total flow resistance from the air supply pipes 24A, 24B, air supply nozzles 25A, 25B, and the two air supply ports of container F after the flow path branches downstream of the MFC 23, until it leaks out into the atmosphere through the exhaust port (not shown) of container F or a gap in the lid Fb. If the total flow resistance after the branching point is equal on both sides of the branch (from the air supply pipes 24A and 24B onward), the flow rate supplied by the MFC 23 is divided equally between the two sides.

[0027] In this embodiment, the flow rate measuring device 30 shown in Figures 3 and 4 is used to inspect the amount of purge gas supplied to each air supply nozzle 25 of each purge device 20 in the storage rack 1. The flow rate measuring device 30 is configured to provide the same flow path resistance as when gas is supplied to the container F, depending on the type of container F, such as a FOUP or reticle pod.

[0028] In the semiconductor transport system SA, each purge device 20 sequentially supplies purge gas in two different air supply modes after the container F is placed on the mounting section 7. That is, each purge device 20 is configured with two different air supply modes for supplying purge gas at different flow rates.

[0029] Figure 5 shows an example of the time variation of the purge gas flow rate in two types of air supply modes. As shown in Figure 5, an initial purge is performed during the initial period from when the container F is placed on the mounting section 7 until time t. In the initial purge, purge gas is supplied at a relatively large flow rate Q1. The initial purge replaces the atmosphere inside the container F with purge gas. The flow rate Q1 in the initial purge can be appropriately set depending on the capacity and specifications of the container F. After time t has elapsed, a maintenance purge is performed. In the maintenance purge, purge gas is supplied at a relatively small flow rate Q2. The flow rate Q2 in the maintenance purge is smaller than the flow rate Q1 in the initial purge, for example, it is less than or equal to half the flow rate Q1. The flow rate Q2 may be less than or equal to one-third of the flow rate Q1, or less than or equal to one-quarter of the flow rate Q1. The maintenance purge maintains the state in which the inside of the container F is filled with purge gas. In other words, the necessary flow rate (small flow rate) sufficient to maintain the state can be set as the flow rate Q2 during maintenance purging. Flow rate control corresponding to these two types of air supply modes is performed, for example, by the control device 21.

[0030] Similar to the supply of purge gas to container F, flow rate measurement (inspection) is performed in the flow rate measuring device 30 using two types of air supply modes. The flow rate measuring device 30 and the flow rate measuring system SB equipped with the flow rate measuring device 30 of this embodiment will be described below with reference to Figures 3, 4, 6, and 7.

[0031] As shown in FIG. 4, the flow rate measurement system SB includes the purge device 20 described above and a flow rate measurement device 30 connected to the air supply nozzles 25A and 25B of the purge device 20. The flow rate measurement device 30 is used for inspecting the purge gas supply function in each purge device 20 as a performance test at the start of operation of the semiconductor transfer system SA or as part of the maintenance of the semiconductor transfer system SA. The flow rate measurement device 30 measures the supply flow rate of the purge gas supplied from the purge device 20 in each purge device 20. The flow rate measurement device 30 can impart the same flow path resistance as when supplying gas to the container according to the discharge flow rate for each of the two types of air supply modes described above.

[0032] FIG. 3 is a perspective view of the flow rate measurement device 30 viewed from the rear. As shown in FIG. 3, the flow rate measurement device 30 has a configuration in which two flow path resistance units 40A and 40B are incorporated in the main body frame 31. The main body frame 31 has a pair of left and right side plate portions 32, a top plate portion 33 connecting the upper ends of the side plate portions 32, and a bottom plate portion 34 connecting the lower ends of the side plate portions 32. A top flange portion 35 disposed at a position above the top plate portion 33 may be attached to the top plate portion 33. In FIG. 3, the XYZ axes are also shown based on the state where the flow rate measurement device 30 is placed on the placement portion 7 of the purge device 20. The top plate portion 33, the bottom plate portion 34, and the top flange portion 35 are plate-like members parallel to the XY plane. The flow path resistance units 40A and 40B are erected at the rear of the bottom plate portion 34. Also, data loggers 37, 37 are installed on the front side of the flow path resistance units 40A, 40B. The flow path resistance units 40A, 40B and the data loggers 37, 37 are housed inside the main body frame 31.

[0033] The flow resistance unit 40A on the left side when viewed from the front, and the flow resistance unit 40B on the right side when viewed from the front, are provided in correspondence with the air supply nozzles 25A and 25B of the purge device 20, respectively. The flow resistance unit 40A includes an introduction section 41A provided so as to be exposed downwards on the bottom plate section 34, a primary pipe 42A connected to the introduction section 41A, and a flow rate measuring device 43 provided on the introduction section 41A for measuring the flow rate of the purge gas flowing through the primary pipe 42A. The flow resistance unit 40A further includes two secondary pipes 46 and 47 connected via a branch section 45 downstream of the primary pipe 42A, a low-flow resistance element 48 provided on the secondary pipe 46, and a high-flow resistance element 49 provided on the secondary pipe 47. The flow resistance unit 40B includes an introduction section 41B provided so as to be exposed downwards on the bottom plate section 34, a primary pipe 42B connected to the introduction section 41B, and a flow rate meter 43 provided on the introduction section 41B for measuring the flow rate of purge gas flowing through the primary pipe 42B. The flow resistance unit 40B further includes two secondary pipes 46 and 47 connected via a branch section 45 downstream of the primary pipe 42B, a low-flow resistance element 48 provided on the secondary pipe 46, and a high-flow resistance element 49 provided on the secondary pipe 47. Thus, the flow resistance unit 40A and the flow resistance unit 40B have the same configuration.

[0034] The introduction parts 41A and 41B are connected to the respective air supply nozzles 25A and 25B. Each of the introduction parts 41A and 41B can be closely attached to the air supply nozzles 25A and 25B, similar to the air supply ports of the container F, and can introduce the purge gas from the air supply nozzles 25A and 25B while ensuring airtightness. Note that the bottom plate portion 34 may be formed with grooves or recesses or the like for receiving the three positioning pins 17 and positioning the flow rate measuring device 30 by these positioning pins 17. The "introduction part" may be referred to as an "introduction port". The primary pipes 42A and 42B are connected to the respective introduction parts 41A and 41B. The flow rate measuring devices 43 provided in the respective primary pipes 42A and 42B are, for example, mass flow meters. The flow rate measuring device 43 outputs the data of the measured supply flow rate of the purge gas to the data logger 37. Each data logger 37 records the data of the supply flow rate measured by each flow rate measuring device 43. Further, it has a display, and the supply flow rate is displayed on the display.

[0035] Resistance elements are provided in each of the secondary pipes 46 and 47 provided in parallel. Each of the small flow rate resistance element 48 and the large flow rate resistance element 49 includes, for example, an orifice. The small flow rate resistance element 48 and the large flow rate resistance element 49 have different inherent resistance characteristics. For example, the opening (hole part) of the orifice included in the small flow rate resistance element 48 is smaller than the opening (hole part) of the orifice included in the large flow rate resistance element 49. Note that the diameters of the secondary pipe 46 and the secondary pipe 47 may be equal, or the diameter of the secondary pipe 46 may be smaller than the diameter of the secondary pipe 47. The diameters of the pipes constituting the flow path resistance units 40A and 40B can be appropriately set according to the above-described respective air supply modes.

[0036] In each of the flow resistance units 40A and 40B, the branch section 45 is provided with a three-way valve 50 (flow path switching section) that switches the flow path of the purge gas to one of the secondary pipes 46 and 47. The three-way valve 50 is operated, for example, manually. The three-way valve 50 allows switching of the flow path of the purge gas according to the selected air supply mode from the two air supply modes that supply purge gas at different supply flow rates. In other words, the flow path of the purge gas is selectively switched to one of the secondary pipes 46 and 47.

[0037] Referring to Figures 5 and 6, the flow rate and pressure loss characteristics in the flow rate measuring device 30 will be explained. The vertical axis in Figure 5 represents the supply flow rate of the MFC 23, and the horizontal axis in Figure 6 represents the flow rate through one flow resistance unit 40. Figure 6 shows the flow rate when there are two flow resistance units 40. It is assumed that the total flow resistance after the branching of the flow path is equal on both sides of the branch (from the air supply pipes 24A, 24B onward). In each of the flow resistance units 40A and 40B, the characteristics represented by curve R2 in Figure 6 are realized by the secondary piping 46 and the low-flow resistance element 48. Curve R2 corresponds to a flow rate range that includes half of the flow rate Q2 during maintenance purging (see also Figure 5). In addition, in each of the flow resistance units 40A and 40B, the characteristics represented by curve R1 in Figure 6 are realized by the secondary piping 47 and the high-flow resistance element 49. Curve R1 corresponds to a flow rate range that includes half of the flow rate Q1 during initial purging (see also Figure 5). In Figure 6, the curve RP is shown by a dashed line as the characteristics at one air supply port of container F. The pressure loss at one air supply port of container F is P2 for half of the flow rate Q2 during maintenance purging, and P1 for half of the flow rate Q1 during initial purging. The resistance characteristics realized by the secondary piping 46 and the low-flow resistance element 48 (curve R2 in Figure 6) are approximately equal to the resistance characteristics of container F at low flow rates (pressure loss P2 for half of the flow rate Q2). Similarly, the resistance characteristics realized by the secondary piping 47 and the high-flow resistance element 49 (curve R1 in Figure 6) are approximately equal to the resistance characteristics of container F at high flow rates (pressure loss P1 for half of the flow rate Q1). As shown in Figure 6, it is difficult for a single flow path resistance element (curve R1 or curve R2) to make the pressure loss with respect to flow rate equivalent to that of container F (curve RP) for each of the multiple flow rates (half of the flow rate Q1, half of the flow rate Q2). Therefore, the primary pipe 42A (or primary pipe 42B) is branched into two secondary pipes 46 and 47, each with its own unique resistance characteristics. By switching these piping paths (purge gas flow paths), it is possible to reproduce the resistance characteristics in container F (the trend of the curve RP for each flow rate range).

[0038] In this embodiment, the resistance characteristics of each of the flow resistance units 40A and 40B, i.e., the flow resistance (pressure loss relative to flow rate) in the secondary piping 46 and 47, are set to a magnitude corresponding to the resistance generated inside a specific container F from among several types of containers such as FOUPs or reticle pods. In each of the flow resistance units 40A and 40B, the flow resistance in the secondary piping 46 and 47 is set using the measured value of the pressure gauge 26 so that, for example, the pressure loss when a container F is placed on the purge device 20 instead of the flow rate measuring device 30 in Figure 4 is equivalent to the pressure loss when the flow rate measuring device 30 is placed on the purge device 20.

[0039] An example of how to use the flow rate measuring system SB and the flow rate measuring device 30 will be described. The operator places the flow rate measuring device 30 on the mounting section 7 of the purge device 20 to be inspected. At this time, the operator may place the flow rate measuring device 30 on the mounting section 7 by holding it by hand, or may place the flow rate measuring device 30 on the mounting section 7 by operating the overhead transport vehicle 3 (by having the top flange section 35 gripped by the overhead transport vehicle 3).

[0040] First, the flow path of the purge gas is switched to one of the secondary pipes by operating the three-way valve 50. The operator first performs a purge gas flow rate test at a low flow rate, for example, simulating a maintenance purge. In this case, the flow path of the purge gas is set to the secondary pipe 46 in both the flow resistance units 40A and 40B. The control device 21 and MFC 23 supply the purge gas at the maintenance purge flow rate Q2. As shown in Figure 7(a), the purge gas flows at half the flow rate Q2 when passing through the secondary pipe 46 and the low flow rate resistance element 48, experiencing a pressure loss P2, if the purge device 20 is functioning correctly. The flow rate meter 43 outputs the measured flow rate data to the data logger 37. After the flow meter 43 has finished measuring the flow rate at one mounting section, the operator moves the flow meter 30 to the mounting section 7 of another purge device 20, for example, while maintaining the setting of the flow path switching section of the flow meter 30, and performs a similar small-flow purge gas flow rate test. Note that in each figure from Figure 7(a) onward, each component is schematically illustrated. Therefore, Figure 4 and Figures 7(a) and 7(b) are slightly different, but they all represent the same device.

[0041] After completing the low-flow purge gas flow rate test for all purge devices 20 under inspection, the operator then performs a high-flow purge gas flow rate test simulating the initial purge. By operating the three-way valve 50, the flow path of the purge gas is switched to the other secondary piping. That is, in both flow resistance units 40A and 40B, the flow path of the purge gas is set to the secondary piping 47. The control device 21 and MFC 23 supply the purge gas at the initial purge flow rate Q1. As shown in Figure 7(b), the purge gas flows at half the flow rate Q1 when passing through the secondary piping 47 and the high-flow resistance element 49, experiencing a pressure loss P1, if the purge device 20 is functioning correctly. The flow rate meter 43 outputs the measured flow rate data to the data logger 37, similar to the low-flow purge gas flow rate test. For example, the operator moves the flow rate measuring device 30 to the mounting section 7 of another purge device 20 while maintaining the position of the flow rate measuring device 30 (i.e., the setting of the flow path switching section), and performs a similar large-flow rate purge gas flow rate test. After completing the small-flow and large-flow rate purge gas flow rate tests for all purge devices 20 to be tested, the operator extracts the measurement data from the data logger 37 and determines whether the purge device 20 is functioning normally (supplying purge gas at the predetermined flow rate).

[0042] Furthermore, as shown in Figures 2, 4, and 7, in a purge device 20 in which multiple air supply nozzles 25 are provided on a single mounting section 7, if the flow rate measuring device 30 is equipped with a flow rate measuring instrument 43 corresponding to each of the air supply nozzles 25, it is also possible to measure the flow rate difference between the air supply nozzles 25 on a single mounting section 7.

[0043] According to the flow rate measuring device 30 of this embodiment, secondary pipes 46 and 47 are connected to the primary pipes 42A and 42B downstream via a branch section 45. The three-way valve 50 switches the flow path of the purge gas to at least one of the secondary pipes 46 and 47. In each of the secondary pipes 46 and 47, multiple different flow resistances can be set by setting the pipe diameter or installing resistance elements so that the flow resistance (or pressure loss) when the purge gas flows becomes a desired value. Therefore, with the flow rate measuring device 30, it is possible to easily switch the flow resistance simply by switching the flow path.

[0044] Furthermore, the flow resistance can be appropriately set for multiple different flow rates in each of the multiple inlet sections 41A and 41B. In addition, the flow rate can be measured in each of the inlet sections 41A and 41B using the flow rate measuring device 43. It is also possible to calculate the flow rate difference between one inlet section and another.

[0045] Furthermore, by appropriately selecting the resistance element (resistance characteristics), a desired flow path resistance can be set for each of several different flow rates. Compared to the configuration described in Patent Document 1 above, where the magnitude of the resistance is changed by operating a knob or the like, in this embodiment, the resistance can be easily set to a fixed value.

[0046] In particular, by appropriately selecting the resistance elements (each resistance characteristic) of the low-flow resistance element 48 and the high-flow resistance element 49 as in this embodiment, the desired flow path resistance can be reliably set for each of several different flow rates. Setting and managing the desired resistance value is easy.

[0047] Furthermore, by operating the three-way valve 50, it is possible to easily switch between two different flow rates for the purge gas.

[0048] The flow resistance in at least one of the secondary pipes 46 and 47 may be set to a size corresponding to the flow rate of purge gas supplied by the purge device 20 for each selected air supply mode. This configuration makes it possible to easily switch to a flow resistance suitable for each air supply mode.

[0049] The flow resistance in at least one of the secondary pipes 46 and 47 is set to a magnitude corresponding to the resistance generated inside a specific container F among several types of containers. This makes it possible to apply the same flow resistance to container F as when gas is supplied to container F, depending on the type of container F.

[0050] According to the flow rate measurement system SB of this embodiment, the supply flow rate of the purge gas is controlled by the MFC 23. The purge gas can be supplied at a desired flow rate, and the desired flow resistance can be set. In addition, the supply pressure of the purge gas can be confirmed by the pressure gauge 26.

[0051] Although embodiments of the present disclosure have been described above, the present invention is not limited to the above embodiments. The present invention is not limited to a configuration in which the resistance value of the resistive element (or resistor) is distinguished according to whether it is for high flow rate or low flow rate. For example, since the pressure loss of the container F may differ depending on at least one of the size and structure of the container F, the resistance value of the resistive element (or resistor) may be set according to the type of container F.

[0052] Alternatively, as shown in Figure 8(a), a flow measuring device 30A may be adopted that includes inlet sections 41A and 41B, but where the piping merges downstream of the inlet sections 41A and 41B, and is equipped with one primary pipe 42 and one flow measuring device 43. Alternatively, as shown in Figure 8(b), a flow measuring device 30B may be adopted that includes one primary pipe 42 and one flow measuring device 43, and is equipped with a common resistance element 55 in the primary pipe 42 and a low-flow resistance element 48 in the secondary pipe 46. In this case, the secondary pipe 46 is a flow path for low flow rates. No resistance element is provided in the secondary pipe 47. The secondary pipe 47 is a flow path for high flow rates. Or, as shown in Figure 8(c), a flow measuring device 30C may be adopted that includes one primary pipe 42 and one flow measuring device 43, and downstream of the branch section 45, an on-off valve 52 is provided in the secondary pipe 46 and an on-off valve 53 is provided in the secondary pipe 47. Note that in Figures 8(a) and subsequent figures, the MFC 23 installed in the air supply piping 22 is not shown.

[0053] Also, as shown in Fig. 9(a), a flow rate measuring device 30D may be adopted which includes one primary pipe 42 and one flow rate measuring instrument 43, and n secondary pipes 54 provided in parallel on the downstream side of the branch portion 45. １ , 54 ２ , ··· 54 ｎ and n resistance elements 56 provided in each secondary pipe. １ , 56 ２ , ··· 56 ｎ A flow rate measuring device 30D having such components may be employed. Between each of the n secondary pipes 54 １ , 54 ２ , ··· 54 ｎ and the branch portion 45 and the resistance elements 56 １ , 56 ２ , ··· 56 ｎ an on-off valve 51 １ , 51 ２ , ··· 51 ｎ is provided. As shown in Fig. 9(b), a flow rate measuring device 30E may be adopted which includes one primary pipe 42 and one flow rate measuring instrument 43, and only one on-off valve 51 is provided in the secondary pipe 47 on the downstream side of the branch portion 45. The secondary pipe 46 is always a flow path through which purge gas flows, but when the on-off valve 51 is opened, purge gas flows through both the secondary pipe 46 and the secondary pipe 47. Alternatively, as shown in Fig. 9(c), a flow rate measuring device 30F may be adopted which includes one primary pipe 42 and one flow rate measuring instrument 43, a common resistance element 55 provided in the primary pipe 42, and a small flow rate resistance element 48 provided in the secondary pipe 46, and only one on-off valve 51 is provided in the secondary pipe 47 on the downstream side of the branch portion 45. No resistance element is provided in the secondary pipe 47. In this case, the secondary pipe 46 is always a flow path through which purge gas flows, but when the on-off valve 51 is opened, purge gas flows through both the secondary pipe 46 and the secondary pipe 47.

[0054] In the configurations shown in Fig. 8(c) and Fig. 9(a), Fig. 9(b) and Fig. 9(c), an on-off valve is provided as the flow path switching portion. Thereby, with a simpler configuration, it is possible to easily switch the flow path of the purge gas corresponding to two types of flow rates.

[0055] A single purge device 20 may have only one air supply nozzle 25. In that case, there is only one air supply port provided on the bottom surface of the container F, only one inlet 41 provided on the flow rate measuring device 30, and only one primary pipe 42.

[0056] For example, as shown in Figure 10(a), a flow measuring device 30G may be employed that includes one inlet 41, one primary pipe 42, one flow measuring instrument 43, and a low-flow resistance element 48 provided in the secondary pipe 46. In this case, the secondary pipe 46 is a flow path for low flow rates. No resistance element is provided in the secondary pipe 47. The secondary pipe 47 is a flow path for high flow rates. Also, as shown in Figure 10(b), multiple (for example, four) secondary pipes 54 are provided in parallel. １ ,54 ２ ,54 ３ ,54 ４ A flow rate measuring device 30H equipped with multiple secondary pipes 54 may be used. １ ,54 ２ ,54 ３ ,54 ４ Each of these has an on / off valve 51 on the downstream side of the branch section 45. １ , 51 ２ , 51 ３ , 51 ４ A resistor is provided. No resistance element is provided in each secondary pipe; the resistance value (pressure loss) is set according to the diameter of each secondary pipe, etc.

[0057] In the embodiments shown in Figures 8 and 9, one flow meter 43 is provided for each of the multiple inlet sections 41, but this is not limited to this configuration. The components from the flow meter 43 onward in the embodiments of Figures 8 and 9 may be arranged in the inlet sections 41A and 41B, respectively.

[0058] Furthermore, the flow rate measuring device 30 may be used in a purge device 20 in which one MFC 23 is provided for multiple mounting sections 7. In this case, by simultaneously installing the flow rate measuring device 30 on all mounting sections 7 connected to one MFC 23, the flow rate difference between the mounting sections of the purge gas distributed from one MFC 23 can be measured.

[0059] Based on the measurement results from the flow rate measuring device 30, the amount of purge gas leaking from the joint between the air supply nozzle 25 and the introduction section 41 at each mounting section 7 may be confirmed.

[0060] A different configuration from the three-way valve 50 in the above embodiment or the on-off valve in the above modified example may be used as the flow path switching section.

[0061] The flow rate measuring device may have a configuration corresponding to a different air supply mode than the initial purge and maintenance purge shown in Figure 5. The different air supply mode may comprise three or more types of air supply modes. When purge gas is supplied at three different supply flow rates, the secondary piping is also configured accordingly. For example, a configuration may be adopted in which two secondary pipes are used and the flow path can be switched between three types: a flow path that passes through both, a flow path that passes through only one, and a flow path that passes through only the other. Three secondary pipes may also be provided.

[0062] The flow rate measuring device 30 and the flow rate measuring system SB may be applied to a purge stocker used as a storage rack. The purge stocker includes racks, cranes, OHT (Overhead Hoist Transfer) ports, etc. In addition to the above, the purge stocker may also have known configurations. The purge stocker is also provided with a purge device, similar to the purge device 20 of the storage rack 1. Each mounting part of the purge device is equipped with a configuration similar to that shown in Figures 2 and 4. Even when applied to a purge stocker, the same operation and effects as the flow rate measuring device 30 and the flow rate measuring system SB in the previous embodiment are achieved.

[0063] Each of the low-flow resistance element 48 and the high-flow resistance element 49 may include a known resistance element other than an orifice. Each of the low-flow resistance element 48 and the high-flow resistance element 49 may include, for example, a variable throttle or a variable valve.

[0064] In addition to the semiconductor transport system SA and purge stocker described above, the purging device and storage rack of this disclosure may also be applied.

[0065] 1...Storage rack, 3...Overhead transport vehicle, 20...Purge device, 22...Air supply piping, 23...MFC (controller), 25, 25A, 25B...Air supply nozzle, 26...Pressure gauge, 30, 30A, 30B, 30C, 30D, 30E, 30F, 30G, 30H...Flow rate measuring device, 31...Main frame, 40A, 40B...Flow rate resistance unit, 41, 41A, 41B...Inlet section, 42, 42A, 42B...Primary piping, 43...Flow rate measuring instrument, 45...Branch section, 46, 47...Secondary piping, 48...Resistance element for low flow rate, 49...Resistance element for high flow rate, 50...Three-way valve (flow rate switching section), F...Container. SB...Flow rate measuring system.

Claims

1. A flow rate measuring device connected to at least one air supply nozzle of a purge device for measuring the supply flow rate of purge gas supplied from the purge device, comprising: at least one introduction section connected to the air supply nozzle for introducing the purge gas; a primary pipe connected to the introduction section; a flow rate measuring instrument provided in the primary pipe for measuring the flow rate of the purge gas flowing through the primary pipe; a plurality of secondary pipes connected to the downstream side of the primary pipe via a branch section; and a flow path switching section for switching the flow path of the purge gas to at least one of the plurality of secondary pipes.

2. The flow rate measuring device according to claim 1, comprising: a plurality of introduction units connected to each of the plurality of air supply nozzles for introducing the purge gas; and a plurality of primary pipes connected to each of the plurality of introduction units, wherein the flow rate measuring device is provided in each of the plurality of primary pipes.

3. The flow rate measuring device according to claim 1 or 2, comprising a resistance element provided in at least one of the plurality of secondary pipes and having a unique resistance characteristic.

4. The flow rate measuring device according to claim 1 or 2, comprising a plurality of resistance elements provided in each of the plurality of secondary pipes and having different inherent resistance characteristics.

5. The flow rate measuring device according to claim 1 or 2, wherein the flow path switching section is a three-way valve provided at the branching section.

6. The flow rate measuring device according to claim 1 or 2, wherein the flow path switching section is an on / off valve provided in the branch section.

7. The flow rate measuring device according to claim 1 or 2, wherein the flow resistance in at least one of the plurality of secondary pipes is set to a magnitude corresponding to the flow rate of purge gas supplied by the purge device for each selected air supply mode.

8. The flow rate measuring device according to claim 1 or 2, wherein the flow resistance in at least one of the plurality of secondary pipes is set to a magnitude corresponding to the resistance generated inside a specific container among the plurality of types of containers.

9. A flow rate measuring system comprising: a purge device having an air supply nozzle; an air supply pipe connected to the air supply nozzle; a pressure gauge attached to the air supply pipe; and a controller provided in the air supply pipe for controlling the supply flow rate of the purge gas; and a flow rate measuring device according to claim 1 or 2 connected to the air supply nozzle.

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