EFEM, and gas supply control method

Abstract

To provide an EFEM capable of keeping a pressure in a housing at a slightly positive pressure at all the time with a specific use amount while avoiding the waste of gas.SOLUTION: In an EFEM comprising main gas supply means, which supplies a gas into a housing 2 via a predetermined supply path 51, and the other gas supply means which supplies gases into the housing 2 via at least one or more supply paths 52 other than the predetermined supply path 51, a control unit 1C which performs control for supplying the gas into at least the housing 2 includes a total gas supply amount setting section 11 for setting a total gas supply amount to be supplied into the housing 2 and an intra-housing gas supply amount calculation section 13 by which, in a case where the gas is being supplied from the other gas supply means via at least one supply path, a gas supply amount into the housing 2 is calculated based on a value obtained by subtracting a gas supply amount supplied by the other gas supply means from the total gas supply amount. The gas supply amount into the housing 2 is controlled in accordance with a gas supply amount command value which is determined based on a calculation result of the calculation section 13.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to an EFEM (Equipment Front End Module) used for automatic substrate transport, and in particular to a control system and method for supplying gas such as nitrogen gas into a housing that is the main body of the EFEM. [Background technology]

[0002] In semiconductor manufacturing processes, substrates are processed in clean rooms to improve yield and quality. In recent years, a "mini-environment system" has been adopted to further improve the cleanliness of only the local space around the substrate, and this system is used to transport and process substrates. In the mini-environment system, a load port is provided adjacent to the housing, forming part of the wall of the housing, which has a nearly closed substrate transport space (hereinafter referred to as the "transfer space") inside. The load port places a FOUP (Front-Opening Unified Pod), a container that stores substrates in the highly clean interior space, and is in close contact with the FOUP door (hereinafter referred to as the "FOUP door") to open and close the FOUP door.

[0003] The load port is a device for loading and unloading substrates into and from a housing, and functions as an interface between the housing and the FOUP. When the load port door (hereinafter referred to as the "load port door"), which is engageable with the FOUP door and opens and closes the FOUP door, is opened, a substrate transport robot located in the transport space within the housing can remove substrates from the FOUP into the housing or store substrates from the housing into the FOUP.

[0004] In the semiconductor manufacturing process, a storage pod called a FOUP is used to maintain an appropriate atmosphere around the substrates, and the substrates are stored and managed inside the FOUP. In particular, in recent years, with the advancement of higher integration of elements and miniaturization of circuits, it is necessary to maintain a high level of cleanliness around the substrates to prevent particles and moisture from adhering to the substrate surface. Therefore, to prevent the surface properties of the substrates from changing, such as oxidation, the inside of the FOUP is filled with nitrogen gas to create an inert nitrogen gas atmosphere around the substrates, or a process called a vacuum (purging process) is carried out.

[0005] Furthermore, an EFEM configured to fill the housing with nitrogen gas, an inert gas, has also been devised and put into practical use (see, for example, Patent Document 1). Specifically, this EFEM comprises a circulation flow path including a transfer space for circulating nitrogen gas within the transfer chamber, a gas supply means for supplying nitrogen gas to the circulation flow path, and a gas discharge means for discharging nitrogen gas from the circulation flow path. The nitrogen gas is supplied and discharged as appropriate in response to fluctuations in the oxygen concentration, etc., within the circulation flow path. This makes it possible to maintain a nitrogen gas atmosphere within the transfer chamber while suppressing increases in the amount of nitrogen gas supplied compared to a configuration in which nitrogen gas is constantly supplied and discharged.

[0006] In the next-generation semiconductor device manufacturing process, which is becoming increasingly miniaturized and multilayered on the nanometer order, there is a need to isolate the substrate transfer space from the external atmosphere and to provide oxidation and corrosion prevention through a high-purity nitrogen gas atmosphere (with extremely low oxygen concentration and humidity) to improve the yield and quality of semiconductor devices. To meet these needs, environmental parameters within the transfer chamber, which were previously not considered important, must be managed at an even higher level. Specific required levels include low humidity (e.g., a dew point humidity of less than -50°C) and low oxygen concentration (e.g., 100 ppm). Furthermore, as semiconductors become increasingly miniaturized and multilayered, substrate degradation during semiconductor manufacturing is becoming a problem. Substrates released toxic substances that degrade the substrates after processing for a long time. For this reason, in recent years, measures have been taken to prevent and suppress deterioration of waiting substrates by adopting a configuration that not only involves a bottom purge process in which a FOUP is placed on a load port and nitrogen gas is purged into the FOUP before the FOUP door is opened, but also continues to supply nitrogen gas from the bottom purge nozzle to substrates waiting inside the FOUP after the FOUP door is opened. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Laid-Open No. 2015-146349 Summary of the Invention [Problem to be solved by the invention]

[0008] However, in conventional EFEMs, the amount of nitrogen gas supplied to the transfer chamber and the amount of nitrogen gas supplied to the load port during bottom purging were controlled separately. Therefore, if the FOUP door was opened and bottom purging was continued while the FOUP was docked to the housing, more nitrogen gas than the specified amount would flow into the housing, causing the problem of increased pressure inside the housing.

[0009] Furthermore, if the pressure becomes higher than the preset value, it is possible to exhaust the nitrogen gas inside the enclosure through the exhaust port, but exhausting the gas just to reduce the pressure when there are no abnormalities in the oxygen concentration or humidity can result in a waste of nitrogen gas.

[0010] The present invention was made with a focus on these issues, and its main purpose is to provide an EFEM and a method for controlling the gas supply into the EFEM that can avoid the waste of nitrogen gas and constantly maintain a slightly positive pressure inside the enclosure with a specified amount of gas used. Note that the present invention is a technology that can also be used for substrate storage containers other than FOUPs. [Means for solving the problem]

[0011] That is, the present invention relates to an EFEM that includes a housing having a substantially closed substrate transfer space therein, and a control unit that controls the supply of inert gas at least into the housing. The EFEM according to the present invention is characterized in that the control unit is configured to include: a total inert gas supply amount setting unit that sets the total supply amount of inert gas to be supplied into the housing based on the oxygen concentration inside the housing; a door open / purge determination unit that determines, for each load port, whether a container door of a substrate storage container placed on a mounting table on which a substrate storage container can be placed is in an open state and whether a purging process is being performed by a purging device that can replace the gas atmosphere inside the substrate storage container placed on the mounting table with inert gas; an intra-enclosure inert gas supply amount calculation unit that calculates the inert gas supply amount into the housing based on a value obtained by subtracting the intra-container inert gas supply amount, which is the amount of inert gas supplied into the substrate storage container by the purging device of the load port, from the total supply amount of inert gas set in the total inert gas supply amount setting unit, when the determination result of the intra-enclosure inert gas supply amount calculation unit is YES; and controls the inert gas supply amount into the housing by an inert gas supply amount command value determined based on the calculation result of the intra-enclosure inert gas supply amount calculation unit.

[0012] The inventors have adopted a novel and useful technical idea of ​​controlling the amount of inert gas (primarily nitrogen gas) supplied into the housing based on the status of purging by the load port, thereby avoiding the waste of nitrogen gas and realizing an EFEM that can always maintain a slightly positive pressure inside the EFEM's transfer chamber with the specified amount of nitrogen gas used.

[0013] In other words, in the EFEM according to the present invention, the amount of inert gas supplied to the EFEM is set based on the oxygen concentration inside the EFEM. When the purging device is performing a purge process with the container door open (the determination result of the door open / purge determination unit is YES), the amount of inert gas used in the purge process (the amount of inert gas supplied to the container) is subtracted from the total amount of inert gas supplied. An inert gas supply command value, which is a command value for the amount of inert gas supplied to the container, is determined based on the subtracted value. The amount of inert gas supplied to the EFEM is then controlled based on the inert gas supply command value. This allows the amount of inert gas supplied to the EFEM as a whole to be controlled so as not to exceed the upper limit (the total amount of inert gas supplied set based on the oxygen concentration inside the EFEM) while taking into account the amount of inert gas used during the purge process. This avoids the waste of inert gas, which is the discharge of inert gas from the container even when the oxygen concentration has not changed. It is therefore possible to conserve inert gas while always maintaining a slightly positive pressure inside the EFEM using the specified amount.

[0014] In particular, in the EFEM according to the present invention, when the inert gas supply control into the enclosure is being executed, and the inert gas supply amount into the enclosure is changed to an inert gas supply amount command value determined based on the calculation results of the inert gas supply amount calculation unit in the enclosure (when the inert gas supply amount command value determined based on the calculation results of the inert gas supply amount calculation unit in the enclosure is updated as the latest inert gas supply amount command value), the amount is controlled to be changed gradually over a predetermined time, thereby preventing and suppressing sudden pressure changes inside the enclosure.

[0015] When the EFEM according to the present invention is configured to include an inert gas supply device in a transfer robot that supplies inert gas to the inside of a substrate transfer robot arranged in the substrate transfer space, or an ionizer that locally supplies inert gas to a substrate placed at a predetermined location in the substrate transfer space to neutralize the substrate, it is preferable to calculate and determine the inert gas supply amount command value taking these inert gas supply amounts into account. Specifically, when the inert gas supply device in the transfer robot is in an inert gas supply state, the inert gas supply amount calculation unit calculates the inert gas supply amount into the housing based on a value obtained by subtracting at least the inert gas supply amount by the inert gas supply device in the transfer robot and the inert gas supply amount into the container from the total inert gas supply amount set by the total inert gas supply amount setting unit. When the ionizer is in an inert gas supply state, the inert gas supply amount calculation unit calculates the inert gas supply amount into the housing based on a value obtained by subtracting at least the inert gas supply amount by the ionizer and the inert gas supply amount into the container from the total inert gas supply amount set by the total inert gas supply amount setting unit.

[0016] Furthermore, an inert gas supply amount control method according to the present invention is an inert gas supply amount control method applicable to an EFEM including a housing having a substantially closed substrate transfer space therein and a controller for controlling the supply of inert gas into the housing, and is characterized in that the method includes: a total inert gas supply amount setting step of setting a total supply amount of inert gas to be supplied into the housing based on an oxygen concentration inside the housing; a door open / purge determination step of determining, for each load port adjacent to the housing, whether a container door of a substrate storage container placed on a mounting table capable of supporting a substrate storage container of that load port is open and whether a purging process is being performed by a purging device; and an inert gas supply amount calculation step of calculating the inert gas supply amount into the housing based on a value obtained by subtracting the inert gas supply amount into the container, which is the amount of inert gas supplied into the substrate storage container by the purging device of that load port, from the total supply amount of inert gas set in the inert gas supply amount setting step, and controlling the inert gas supply amount into the housing based on the calculation result in the inert gas supply amount into the housing calculation step.

[0017] The inert gas supply amount control method according to the present invention can achieve the same effects as those achieved by the EFEM according to the present invention described above, and can avoid a situation in which more inert gas than the initial control amount is supplied into the enclosure. As a result, it is possible to prevent a pressure increase inside the enclosure and to solve the problem of supplying excess inert gas, i.e., the problem of wasting inert gas by discharging inert gas even when the oxygen concentration has not changed, thereby saving inert gas. [Effects of the Invention]

[0018] According to the present invention, when an inert gas such as nitrogen gas is supplied into the enclosure, the inert gas supply amount is controlled based on a value calculated by subtracting the gas supply amount (inert gas supply amount into the container) supplied into the substrate storage container by the purge device of the load port from the gas supply amount, which is the initial control amount into the enclosure. Therefore, it is possible to provide an EFEM and an inert gas supply control method into the EFEM that can avoid wasting inert gas and always maintain the pressure inside the enclosure at a slightly positive pressure with the specified usage amount. [Brief explanation of the drawings]

[0019] [Figure 1] FIG. 1 is a side view showing a schematic diagram illustrating the relative positional relationship between an EFEM and its peripheral devices according to an embodiment of the present invention. [Figure 2] FIG. 2 is a diagram schematically showing a gas piping system in the embodiment. [Figure 3] FIG. 2 is a functional block diagram of a control unit in the embodiment. [Figure 4] FIG. 4 is a diagram showing an example of an oxygen concentration control table in the embodiment. [Figure 5] 10 is a simplified flowchart of control of the amount of inert gas supplied into the enclosure in the embodiment. [Figure 6] 10 is a detailed flowchart of control of the amount of inert gas supplied into the enclosure in the embodiment. [Figure 7] FIG. 4 is a diagram showing an example of an oxygen concentration control table in the embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0020] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0021] As shown in Figure 1, the EFEM 1 (Equipment Front End Module) according to this embodiment comprises a housing 2, which is the main body, placed in a clean room during the semiconductor manufacturing process, and a load port 3. Figure 1 also shows a schematic diagram of the relative positional relationship between the EFEM 1 and its peripheral devices. The FOUP 4 shown in the figure is a type of "substrate storage container" in the present invention, and is used together with the EFEM 1.

[0022] A processing device M (semiconductor processing device) is provided adjacent to the rear wall 2b of the housing 2, which faces the front wall 2a on which the load port 3 is disposed. In other words, by connecting the load port 3 to an opening provided in the front wall 2a of the housing 2 and connecting the processing device M to an opening provided in the rear wall 2b, a substantially closed space (substrate transfer space 2Sa, FFU placement space 2Sb) is formed inside the housing 2.

[0023] In the clean room, the internal space MS of the processing device M, the internal space of the housing 2, that is, the substrate transfer space 2Sa, the FFU placement space 2Sb, and the internal space 4S of the FOUP 4 placed on the load port 3 are maintained at a high level of cleanliness.

[0024] In this embodiment, as shown in Fig. 1, the load port 3, housing 2, and processing device M are arranged in close proximity to one another in this order in the forward / backward direction X of the EFEM 1. The operation of the EFEM 1 is controlled by a controller for the entire EFEM 1 (controller 1C shown in Fig. 1) and a controller for the load port 3 (controller 3C shown in Fig. 1), while the operation of the processing device M is controlled by a controller for the processing device M (controller MC shown in Fig. 1). The controller MC, which is the controller for the entire processing device M, and the controller 1C, which is the controller for the entire EFEM 1, are higher-level controllers of the controller 3C for the load port 3. Each of these controllers 1C, 3C, and MC is composed of a normal microprocessor or the like equipped with a CPU, memory, and interface. Programs required for processing are stored in advance in the memory, and the CPU sequentially retrieves and executes the required programs to achieve the desired functions in cooperation with peripheral hardware resources.

[0025] A substrate transfer robot R capable of transferring substrates W (semiconductor wafers) between the FOUP 4 and the processing equipment M is provided in the substrate transfer space 2Sa, which is an internal space of the housing 2 (see FIG. 1). An FFU 23 (fan filter unit) is provided in the FFU placement space 2Sb, which is a space above the substrate transfer space 2Sa within the internal space of the housing 2. Driving the FFU 23 generates a downward air current in the substrate transfer space 2Sa of the housing 2, allowing a highly clean gas (an inert gas (environmental gas) such as nitrogen gas) to circulate in the substrate transfer space 2Sa. A circulation path 21 for circulating nitrogen gas is formed inside the housing 2. The circulation path 21 is composed of the substrate transfer space 2Sa, the FFU installation space 2Sb, and a return path 22. In the circulation path 21, clean nitrogen gas is sent downward from the FFU installation space 2Sb through the FFU 23, reaches the lower end of the substrate transfer space 2Sa, then ascends through the return path 22 and returns to the FFU installation space 2Sb.

[0026] The FFU 23 uses a fan to send nitrogen gas from the FFU installation space 2Sb downward, while removing particles contained in the nitrogen gas using a filter. The purified nitrogen gas is sent from the FFU installation space 2Sb to the substrate transfer space 2Sa, where it forms a laminar flow and flows downward. The nitrogen gas that reaches the lower end of the substrate transfer space 2Sa flows into the return path 22 through an opening 22a formed at the lower end of the return path 22. In this embodiment, the nitrogen gas is sucked into the return path 22 by a fan 22b provided above the opening 22a and sent upward, returning it to the FFU installation space 2Sb. The nitrogen gas returned to the FFU installation space 2Sb is purified by the FFU 23 and sent again to the substrate transfer space 2Sa. The return path 22 is a path isolated from the substrate transport space 2Sa and the FFU installation space 2Sb by a partition wall 22c (such as an appropriate support wall), and is configured so that only the opening 22a formed at the lower end of the return path 22 communicates with the substrate transport space 2Sa, and only the upper end of the return path 22 communicates with the FFU installation space 2Sb.

[0027] The above configuration enables nitrogen gas to circulate within the circulation path 21. A supply path 51 that supplies nitrogen gas into the circulation path 21 is connected to a side of the FFU installation space 2Sb. As shown in FIG. 2, the supply path 51 is connected to a nitrogen gas supply source 50. A mass flow controller (MFC) 51a that measures and controls the flow rate of the supply path 51, which is a gas flow path, and a supply valve 51b that can change the amount of gas supplied per unit time are provided at a predetermined location on the supply path 51. In this embodiment, a sub-supply path 52 is provided that branches off from a predetermined location on the supply path 51 that is upstream of the MFC 51a and the supply valve 51b, and the sub-supply path 52 is connected to a predetermined location on the supply path 51 that is downstream of the MFC 51a and the supply valve 51b. A supply valve 52b that switches the nitrogen gas supply ON / OFF is provided at a predetermined location on the sub-supply path 52. Note that "FM" in FIG. 2 represents a flow meter 52a. Therefore, in this embodiment, part of the gas supply amount into circulation path 21 can be made to correspond to the gas supply amount through sub-supply path 52. In this embodiment, the supply source of supply path 51 is configured to be switchable between the above-mentioned nitrogen gas supply source 50 and a CDA (clean dry air) supply source shown in Fig. 2. Lowercase Roman numerals shown in Fig. 1 are used to indicate continuation of the same lowercase Roman numerals shown in Fig. 2.

[0028] 1, an exhaust pipe 22d for exhausting gas from the circulation path 21 is connected to the front end of the substrate transfer space 2Sa. The exhaust pipe 22d is connected to the outside space. A predetermined location on the exhaust pipe 22d is provided with an exhaust valve that is controlled according to the pressure in the housing 2 and can change the amount of gas exhausted per unit time from the circulation path 21. This makes it possible to appropriately supply and exhaust nitrogen gas to and from the circulation path 21 to perform a process for adjusting the oxygen concentration in the internal space of the housing 2 (also referred to as an internal housing purge process or an EFEM purge process). For example, if the oxygen concentration in the circulation path 21 increases, the oxygen concentration can be lowered by temporarily supplying a large amount of nitrogen gas from the supply source 50 to the circulation path 21 via the supply path 51 (including the sub-supply path 52) and exhausting the oxygen together with the nitrogen gas via the exhaust pipe 22d. The control unit 1C is electrically connected to the oxygen concentration meter 2e, pressure meter 2f, hygrometer 2g, etc. installed inside the housing 2, and receives the measurement results of these measuring instruments to grasp information about the atmosphere inside the housing 2 (for ease of explanation, in Figure 1, the oxygen concentration meter 2e, pressure meter 2f, and hygrometer 2g are shown outside the housing 2 together with the control unit 1C).

[0029] As shown in FIG. 1 , the FOUP 4 placed on the load port 3 includes a FOUP body 42, the internal space 4S of which can be opened only rearward through a loading / unloading port 41, and a FOUP door 43 (corresponding to the "container door 43" of the present invention) that can open and close the loading / unloading port 41. The FOUP 4 is a known container with multiple slots formed therein, each capable of accommodating a substrate W to be transported, and the substrates W can be loaded and unloaded through the loading / unloading port 41. The upward surface of the FOUP body 42 is provided with a flange portion 44 that can be gripped by a device that automatically transports the FOUP 4 (e.g., an overhead transport (OHT)). The FOUP 4 is placed on the loading platform 35 of the load port 3. A port (not shown) is provided in the bottom wall of the FOUP body 42. The port is, for example, primarily a hollow cylindrical grommet seal fitted into a port-mounting through-hole formed in the bottom wall of the FOUP body 42, and is configured to be openable and closable by a check valve.

[0030] As shown in Figure 1, the load port 3 of this embodiment comprises a plate-shaped frame 32 that forms part of the front wall 2a of the housing 2 and has an opening 31 formed therein for opening the internal space (substrate transport space 2Sa) of the housing 2, a load port door 33 that opens and closes the opening 31 in the frame 32, a door opening / closing mechanism 34 that opens the opening 31 in the frame 32 by moving the load port door 33 to a door open position retracted toward the housing 2, and a loading platform 35 that is mounted on the frame 32 in an approximately horizontal position.

[0031] The frame 32 is arranged in an upright position and has a generally rectangular plate shape with an opening 31 large enough to communicate with the loading / unloading opening 41 of the FOUP 4 placed on the mounting table 35. The opening 31 of the frame 32 is shown schematically in FIG.

[0032] The mounting table 35 is provided on top of a horizontal base 351 (support base) that is disposed in a substantially horizontal position slightly above the center of the frame 32 in the height direction, and is capable of mounting a FOUP 4 with the FOUP door 43, which opens and closes the internal space 4S of the FOUP body 42, facing the load port door 33. The mounting table 35 is configured to be movable toward and away from the frame 32 between a predetermined docking position where the FOUP door 43 approaches the opening 31 of the frame 32 and a position (see FIG. 1) where the FOUP door 43 is spaced a predetermined distance from the frame 32 beyond the docking position. In this embodiment, in the front-to-rear direction X (see FIG. 1, etc.) in which the FOUP 4 mounted on the mounting table 35 and the frame 32 are aligned, the FOUP 4 side is defined as the front, and the frame 32 side is defined as the rear.

[0033] The load port door 33 is configured to be movable integrally with the FOUP door 43 by the door opening / closing mechanism 34 while maintaining an engaged state with the FOUP door 43 between a fully closed position in which the opening 31 of the frame 32 is sealed, a door open position in which the door is retracted toward the housing 2 from the fully closed position, and a fully open position in which the opening space of the opening 31 is fully opened rearward. As shown in FIG. 1 , the load port door 33 and the door opening / closing mechanism 34 are positioned so as to overlap the return path 22 of the circulation path 21 in a side view. However, in reality, the circulation paths 21 are provided at a predetermined pitch in the width direction of the housing 2, and the load port door 33 is configured to move integrally with the FOUP door 43 by the door opening / closing mechanism 34 in the space formed between the circulation paths 21 aligned in the width direction and communicating with the substrate transfer space 2Sa. Therefore, the load port door 33 does not move together with the FOUP door 43 on the return path 22.

[0034] The load port 3 of this embodiment is equipped with a bottom purge device 36 (corresponding to the "purge device" of the present invention) that can inject a purge gas made of an inert gas such as nitrogen gas into the internal space 4S of the FOUP 4 and replace the gas atmosphere in the internal space 4S of the FOUP 4 with the purge gas. The bottom purge device 36 is equipped with a plurality of purge nozzles 37 (gas supply / exhaust device) that are arranged at predetermined positions on the mounting table 35 with their upper ends exposed. These multiple purge nozzles 37 are attached to appropriate positions on the mounting table 35 in accordance with the positions of ports provided on the bottom surface of the FOUP 4 and can be connected in contact with the ports. In a bottom purge process (corresponding to the "purging process" of the present invention) using such a bottom purge device 36, a predetermined number (excluding all) of the multiple ports provided at the bottom of the FOUP 4 are made to function as "supply ports," and an appropriately selected purge gas, such as nitrogen gas, inert gas, or dry air, is injected into the FOUP 4 through purge nozzles 37 connected to the supply ports. The remaining ports are made to function as "exhaust ports," and the gas atmosphere within the FOUP 4 is exhausted through the purge nozzles 37 connected to the exhaust ports, thereby filling the FOUP 4 with the purge gas. Each load port 3 is provided with a supply path 61 that supplies nitrogen gas to the purge nozzles 37 connected to the supply ports. As shown in FIG. 2, the supply path 61 is connected to a nitrogen gas supply source 60 for the bottom purge process. Note that "LP Purge" in FIG. 2 refers to load port purge, and indicates that the supply source 60 is the source of nitrogen gas used in the bottom purge process. At a predetermined position of the supply path 61, there is provided an MFC 61a (Mass Flow Control Unit) for measuring and controlling the flow rate of the supply path 61, which is a gas flow path. The FOUP 4 is provided with a gas supply valve 61b that can change the amount of gas supplied per unit time. The purge nozzle connected to the exhaust port is connected to an exhaust pipe (not shown) for exhausting gas from the FOUP 4.

[0035] As shown in Fig. 1, the substrate transport robot R is an articulated robot having a base R1 fixed within the substrate transport space 2Sa and an arm R2 whose base end is rotatably supported on the base R1, and having multiple arm elements R3, R4, R5 and a hand R6 that constitute the arm R2 connected to the base R1 so that they can be rotated sequentially. In this embodiment, the arm R2 has three arm elements R3, R4, R5 and two (two-tiered) hands R6, and the arm elements R3, R4, R5 rotate to horizontally move the hand R6 that holds the substrate W. Note that the number of arm elements and hands is not limited to this. The arm elements R3, R4, R5 are arranged in this order from the bottom up. Specifically, the base end of the lowest arm element R3 is rotatably connected to the base R1, the base end of the middle arm element R4 is rotatably connected to the tip end of the lowest arm element R3, the base end of the top arm element R5 is rotatably connected to the tip end of the middle arm element R4, and the robot hand R6 is rotatably connected to the tip end of the top arm element R5.

[0036] The internal spaces R3a, R4a, and R5a of the arm elements R3, R4, and R5 are interconnected via gaps in predetermined containers. The robot hand R6 can hold the substrate W by operating mechanical components such as a cylinder R7 built into the robot hand R6. The rod (not shown) of the cylinder R7 is configured to be extendable and retractable in a predetermined direction by supplying nitrogen gas from a supply source (not shown) separate from the above-mentioned supply source 50.

[0037] The EFEM 1 includes an ejector R8 inside the substrate transport robot R that sucks and removes particles generated by the operation of the cylinder R7. Nitrogen gas is supplied to the ejector R8 from the supply source 50 through a supply path 53, and particles generated by the operation of mechanical components such as the cylinder are sucked in through a suction path 531. The nitrogen gas supplied to the ejector R8 flows along an appropriate path (a connection path R12, described later) together with the sucked particles and is then sent to the return path 22. In other words, the nitrogen gas flows into the circulation path 21 without being discharged directly to the external space of the housing 2. In this way, particles generated near the cylinder R7 are sucked in by the ejector R8, and the nitrogen gas supplied from the supply source 50 is discharged along with the particles to the return path 22, so that the nitrogen gas circulates as is. Furthermore, the particles are removed by the FFU 23. Therefore, compared to a configuration that performs vacuum evacuation, the increase in cost due to the replenishment of nitrogen gas can be suppressed. In this embodiment, the supply source 50 that supplies nitrogen gas to the ejector R8 is the same as the supply source 50 that supplies nitrogen gas into the circulation path 21 (shared supply source), and a supply valve 53a that switches the supply of nitrogen gas ON / OFF is provided at a predetermined position in the supply path 53 to the ejector R8. Note that "FM" in FIG. 2 denotes a flow meter 53a. The supply path 53 to the ejector R8 branches off from a predetermined position upstream of the MFC 51a and the supply valve 51b in the supply path 51 that functions as a gas supply path during the above-mentioned purging process inside the housing.

[0038] Furthermore, a delivery port R11 for delivering nitrogen gas to the circulation path 21 is formed at a predetermined location on the base R1 of the transport robot R, and the delivery port R11 is connected to the return path 22 by a connection path R12. A fan R13 that rotates at a constant rotational speed is provided near the delivery port R11. The EFEM1 of this embodiment is equipped with a supply path 54 that passes through the internal space R1a of the base R1 and the internal spaces R3a, R4a, and R5a of the arm elements R3, R4, and R5, and the tip of the supply path 54 is located within the internal space R5a of the uppermost arm element R5. When an inert gas such as nitrogen gas is supplied from the supply source 50 to the supply path 54, the inert gas passes through the supply path 54 and is supplied to the internal space R5a of the uppermost arm element R5, then flows into the internal space R4a of the middle arm element R4, the internal space R3a of the lowermost arm element R3, and the internal space R1a of the base part R1, in that order, and is sent out through the outlet R11 of the base part R1 to the return path 22. This allows the gas in the internal spaces of the transfer robot R (the internal space R1a of the base part R1, and the internal spaces R3a, R4a, and R5a of the arm elements R3, R4, and R5) to be replaced with an inert gas such as nitrogen gas.

[0039] As described above, the EFEM 1 of this embodiment is equipped with the transfer robot internal purge device R9 that replaces the gas in the internal space of the transfer robot R (the internal space R1a of the base part R1 and the internal spaces R3a, R4a, and R5a of the arm elements R3, R4, and R5) with an inert gas such as nitrogen gas. Therefore, even if particles are generated in the internal space of the transfer robot R (the internal space R1a of the base part R1 and the internal spaces R3a, R4a, and R5a of the arm elements R3, R4, and R5), the particles can be prevented from leaking into the substrate transfer space 2Sa. Furthermore, the particles discharged into the return path 22 are removed by the FFU 23 arranged downstream of the return path 22. Therefore, the substrate transfer space 2Sa can be prevented from being contaminated by particles generated in the internal space of the substrate transfer robot R (the internal space R1a of the base part R1 and the internal spaces R3a, R4a, and R5a of the arm elements R3, R4, and R5). In this embodiment, the supply source 50 that supplies nitrogen gas to the transfer robot internal purging device R9 is the same as the supply source 50 that supplies nitrogen gas into the circulation path 21 (sharing of the supply source), and a supply valve 54b that switches the supply of nitrogen gas ON / OFF is provided at a predetermined position in the supply path 54. The supply path 54 to the transfer robot internal purging device R9 branches off from a predetermined position upstream of the MFC 51a and supply valve 51b in the supply path 51 that functions as a gas supply path during the above-mentioned purging process inside the housing.

[0040] The above-mentioned ejector R8 and the transfer robot internal purge device R9 each correspond to the "transfer robot internal inert gas supply device that supplies inert gas to the internal space of the substrate transfer robot" in the present invention.

[0041] 1, the EFEM 1 of this embodiment is provided with an aligner 7 in the substrate transfer space 2Sa. The aligner 7 detects the amount of deviation of the holding position of a substrate W held by the arm R2 of the transfer robot R from a target holding position and performs position correction (alignment) to correct the position deviation. The aligner 7 includes an alignment table 71 on which the substrate W to be aligned is placed. A through-hole 73 formed in the side wall of an alignment case 72 containing a mechanism for rotating the alignment table 71 is connected to the return path 22 by a connection path 74. In this embodiment, a fan 75 is provided near the through-hole 73 of the alignment case 72. When the fan 75 is rotated, gas inside the alignment case 72 is discharged toward the connection path 74 together with particles generated inside the alignment case 72.

[0042] The EFEM 1 of this embodiment includes an ionizer 8 that sprays nitrogen gas, which is ionized air, from above onto a substrate placed on an alignment table 71. The ionizer 8 is connected to a supply path 55 through which an inert gas supplied from a supply source 50 flows, and by spraying the inert gas (ionized air) supplied from the supply source 50 onto the substrate W placed on the alignment table 71, it is possible to neutralize and remove (de-ionize) static electricity charged on the substrate W. In this embodiment, as shown in FIG. 2, the supply source 50 that supplies nitrogen gas to the ionizer 8 is the same as the supply source 50 that supplies nitrogen gas into the circulation path 21 (shared supply source), and a supply valve 55b that switches the supply of nitrogen gas ON / OFF is provided at a predetermined position on the supply path 55 to the ionizer 8. "FM" shown in FIG. 2 is a flow meter 55a. The supply path 55 to the ionizer 8 branches off from the supply path 51, which functions as a gas supply path during the above-described purging process inside the housing, at a predetermined position upstream of the MFC 51a and the supply valve 51b.

[0043] Next, the operation flow of the EFEM1 will be described. First, a FOUP 4 is transported above the load port 3 by a container transport device such as an OHT and placed on the mounting table 35. At this time, for example, a positioning protrusion provided on the mounting table 35 fits into a positioning recess on the FOUP 4, causing a locking claw on the mounting table 35 to enter a locked state (locking process). In this embodiment, a FOUP 4 can be placed on each of the mounting tables 35 of three load ports 3 arranged side by side in the width direction of the housing 2. In addition, a seating sensor (not shown) that detects whether the FOUP 4 is placed in a predetermined position on the mounting table 35 can be used to detect whether the FOUP 4 has been placed in the correct position on the mounting table 35.

[0044] In the load port 3 of this embodiment, when a FOUP 4 is placed in the correct position on the mounting table 35, it detects that the bottom of the FOUP 4 is pressing against a pressure-receiving portion of, for example, a pressure sensor provided on the mounting table 35. This triggers the purge nozzles 37 (all of the purge nozzles 37) provided on the mounting table 35 to extend above the upper surface of the mounting table 35 and connect to the respective ports of the FOUP 4, switching each port from a closed state to an open state. The load port 3 of this embodiment then supplies nitrogen gas to the internal space 4S of the purged FOUP 4 using the bottom purge device 36, thereby replacing the internal space 4S of the FOUP 4 with nitrogen gas (bottom purge process). During the bottom purge process, the gas atmosphere within the FOUP 4 is exhausted to the outside of the FOUP 4 through the purge nozzles 37 connected to a port that functions as an exhaust port. By such bottom purging, the moisture concentration and oxygen concentration in the FOUP 4 are reduced to or below predetermined values, respectively, to create a low-humidity and low-oxygen environment around the substrates W in the FOUP 4. The amount of nitrogen gas supplied to the internal space 4S of the FOUP 4 during the bottom purging can be changed by the bottom purging MFC 61a, and the supply flow rate of nitrogen gas can be changed according to the moisture concentration and oxygen concentration in the FOUP 4.

[0045] 1 to a predetermined docking position, the load port 3 of this embodiment closely contacts the FOUP door 43 and the frame 32. Then, the FOUP door 43 is moved together with the load port door 33 to open the opening 31 of the frame 32 and the loading / unloading entrance 41 of the FOUP 4, thereby performing a process (door opening process) to release the sealed state inside the FOUP 4. By performing the door opening process, the internal space 4S of the FOUP body 42 and the substrate transfer space 2Sa of the housing 2 are brought into communication, and the substrate transfer robot R provided in the substrate transfer space 2Sa of the housing 2 performs a process (transfer process) to retrieve a substrate W from a slot in the FOUP body 42 or store a substrate W in a specific slot.

[0046] In the load port 3 according to this embodiment, when all of the substrates W in the FOUP 4 have completed the processing steps in the processing device M, the door drive mechanism 34 moves the load port door 33 to the fully closed position, closing the opening 31 in the frame 32 and the loading / unloading entrance 41 of the FOUP 4, and performing a process (door closing process) to seal the internal space 4S of the FOUP 4. Through the above process, the opening 31 in the frame 32 and the loading / unloading entrance 41 of the FOUP 4 are closed by the load port door 33 and the FOUP door 43, respectively, and the internal space 4S of the FOUP 4 becomes sealed.

[0047] Next, the load port 3 according to this embodiment moves the mounting table 35 in a direction away from the frame 32 to release the locked state of the FOUP 4. As a result, the FOUP 4 storing the substrates W that have undergone the predetermined processing is transferred from the mounting table 35 of each load port 3 to the container transport device and carried out to the next process.

[0048] In the EFEM 1 according to this embodiment, which follows this operational flow, the bottom purge process, which is performed before the door-open process, can be continued after the door-open process, thereby preventing or suppressing deterioration of substrates waiting in the FOUP 4. On the other hand, continuing the bottom purge process after the door-open process may cause nitrogen gas, which is the purge gas, to flow from the FOUP 4 into the housing 2, which may increase the pressure inside the housing 2. To avoid this situation, the EFEM 1 according to this embodiment is configured so that the amount of inert gas supplied into the housing 2 is controlled by the control unit 1C. Specifically, the control unit 1C is configured to control the amount of inert gas supplied into the housing 2 based on an inert gas supply amount command value.

[0049] As shown in FIG. 3, the control unit 1C includes an inert gas supply total amount setting unit 11, a door open / bottom purge determination unit 12 (corresponding to the "door open / purge determination unit" of the present invention), an inert gas supply amount calculation unit 13 within the housing, and a command value determination unit 14.

[0050] The inert gas supply total amount setting unit 11 sets the total amount of inert gas to be supplied into the housing 2 based on the oxygen concentration inside the housing 2. In this embodiment, as shown in Fig. 4, the total amount of inert gas to be supplied into the housing 2 according to the oxygen concentration inside the housing 2 is stored in a predetermined storage area of ​​the control unit 1C as an oxygen concentration control table.

[0051] The door open / bottom purge determination unit 12 determines, for each load port 3, whether the container door 43 of the FOUP 4 placed on the mounting table 35 of that load port 3 is in an open state and whether a bottom purge process is being performed by the bottom purge device 36. Whether the container door 43 of the FOUP 4 is in an open state can be determined by an appropriate sensor (such as a U-shaped microphotosensor) provided near the container door 43 of the FOUP 4 on the load port 3, and whether a bottom purge process is being performed by the bottom purge device 36 can be determined by an appropriate sensor (such as a gas flow meter) provided in association with the bottom purge device 36. Since the EFEM 1 of this embodiment is equipped with three load ports 3, the door open / bottom purge determination unit 12 performs the determination process for each load port 3 (a total of three times).

[0052] When the determination result of the door open / bottom purge determination unit 12 is YES, the inert gas supply amount calculation unit 13 calculates the amount of inert gas to be supplied into the housing 2 based on a value obtained by subtracting the amount of bottom purge inert gas supplied to the FOUP 4 by the bottom purge device 36 of the load port 3 (corresponding to the "inner container inert gas supply amount" of the present invention) from the inert gas supply amount set by the total inert gas supply amount setting unit 11. The amount of bottom purge inert gas supplied to the FOUP 4 by the bottom purge device 36 is a value that varies depending on the oxygen concentration in the FOUP 4, the duration of the bottom purge process, etc., and this value (bottom purge inert gas supply amount) is based on the command value of the bottom purge MFC 61a. Therefore, by specifying the command value of the bottom purge MFC 61a by an appropriate means, the amount of bottom purge inert gas to be supplied to the FOUP 4 by the bottom purge device 36 can be specified, and the specified value can be used for the calculation processing in the inert gas supply amount calculation unit 13. Furthermore, when the determination result of the door open / bottom purge determination unit 12 is No (when the container door 43 of the FOUP 4 placed on the loading platform 35 of the load port 3 is closed, or when the bottom purge process is not being performed by the bottom purge device 36), the inert gas supply amount calculation unit 13 in the housing calculates the amount of inert gas to be supplied into the housing 2, assuming that the value to be subtracted from the total inert gas supply amount set by the total inert gas supply setting unit 11 is zero (the amount of bottom purge inert gas supplied to the FOUP 4 by the bottom purge device 36 of the load port 3 is zero).

[0053] Furthermore, when the inert gas supply device in the transfer robot is in an inert gas supply state, the inert gas supply amount calculation unit 13 in the housing 2 is configured to subtract the inert gas supply amount by the inert gas supply device in the transfer robot from the total inert gas supply amount set by the total inert gas supply amount setting unit 11 to calculate the inert gas supply amount into the housing 2. In this embodiment, the ejector R8 and the inert gas supply device R9 in the transfer robot correspond to the inert gas supply device in the transfer robot, and when the ejector R8 is in an inert gas supply state, the inert gas supply amount calculation unit 13 in the housing 2 is configured to subtract the inert gas supply amount of the ejector R8 from the total inert gas supply amount to calculate the inert gas supply amount into the housing 2, and when the inert gas supply device R9 in the transfer robot is in an inert gas supply state, the inert gas supply amount calculation unit 13 is configured to subtract the inert gas supply amount of the inert gas supply device R9 in the transfer robot from the total inert gas supply amount to calculate the inert gas supply amount into the housing 2.

[0054] In addition, in this embodiment, when the ionizer 8 is in an inert gas supply state, the inert gas supply amount calculation unit 13 in the housing is configured to calculate the inert gas supply amount into the housing 2 by subtracting the inert gas supply amount of the ionizer 8 from the total inert gas supply amount.

[0055] Here, column C in the oxygen concentration control table in FIG. 4 is a column relating to the inert gas supply amount of the "Robot Ejector" (ejector R8), column D is a column relating to the inert gas supply amount of the "Robot Inner Purge" (transport robot internal purging device R9), and column E is a column relating to the inert gas supply amount of the "Ionizer Purge" (ionizer 8). Also, column B in the oxygen concentration control table is a column relating to "Main Purge," that is, the amount of inert gas supplied into the housing 2 through the above-mentioned sub-supply path 52. The supply amounts in columns B to E do not vary depending on the value of the oxygen concentration in the housing 2 (oxygen concentration in the EFEM), but are zero or a constant value (fixed value).

[0056] The command value determination unit 14 determines the calculation result of the inert gas supply amount calculation unit 13 in the housing as a command value for the amount of inert gas to be supplied into the housing 2. In this embodiment, when the amount of inert gas to be supplied into the housing 2 is changed (updated) to an inert gas supply amount command value determined based on the calculation result of the inert gas supply amount calculation unit 13 in the housing, that is, when updating from the current inert gas supply amount command value to the latest inert gas supply amount command value (the latest inert gas supply amount command value determined by the command value determination unit 14), the current inert gas supply amount command value is gradually changed to the latest inert gas supply amount command value over a predetermined time period.

[0057] When the EFEM 1 of this embodiment is powered on and started, it enters a maintenance mode in which it performs an atmosphere replacement process inside the housing 2. In this maintenance mode, it performs atmosphere replacement to raise the oxygen concentration inside the housing 2 from less than 19.5% to 19.5% or more. The EFEM 1 transitions from the maintenance mode to the transfer mode, and then from the transfer mode to the transfer mode with oxygen concentration control. In the transfer mode with oxygen concentration control, the control unit controls the supply of inert gas (control of the oxygen concentration inside the housing).

[0058] When the transition to the oxygen concentration controlled transfer mode begins, the EFEM 1 monitors the value of the oxygen concentration meter 2e installed at an appropriate location inside the housing 2 and controls the oxygen concentration to be constant (oxygen concentration control inside the transfer chamber).

[0059] As described above, the oxygen concentration control table shown in Fig. 4 is stored in advance in a predetermined storage area of ​​the control unit 1C. Then, once per second, calculation processing is performed according to the following equation 1 in accordance with the oxygen concentration, and the amount of inert gas supplied to the housing 2, which is the control target, is set in accordance with the calculation result; specifically, the flow rate to the MFC 51a for purging inside the housing, which is provided at a predetermined location in the supply path 51 that supplies nitrogen gas into the circulation path 21 of the housing 2, is set. A(LPM)=T-(B+C+D+E+F+G+H)...Equation 1 Here, A through H in Equation 1 are synonymous with A through H in the oxygen concentration control table of FIG. 4, respectively. A is the inert gas supply amount (EFEM MFC Purge) into the housing 2, which is the control target. Specifically, it is the flow command value for the MFC 51a for purging inside the housing, and is expressed in units of LPM (liters per minute). T is the total inert gas supply amount (total N2 supply amount (LPM)) into the housing 2, which is preset according to the oxygen concentration inside the housing 2. Furthermore, B, C, D, and E in Equation 1 are the main purge inert gas supply amount (Main Purge (LPM)), the ejector inert gas supply amount (Robot Ejector (LPM)), the transfer robot inner purge inert gas supply amount (Robot Inner Purge (LPM)), and the ionizer inert gas supply amount (Ionizer Purge (LPM)), respectively. In Equation 1, F, G, and H are the inert gas supply rates (LP-1 MFC Purge (LPM), LP-2 MFC Purge (LPM), and LP-3 MFC Purge (LPM)) of the bottom purge devices 36 of the first, second, and third load ports, respectively. Columns N and T in the oxygen concentration control table are individual parameters, and columns B to E are parameters for each column. The oxygen concentration control table in Figure 3 shows an example of default values.

[0060] In this embodiment, when "A<5", the flow rate setting for the MFC 51a for purging inside the enclosure is set to 5 LPM. This is because the control range of the MFC 51a for purging inside the enclosure is 4 to 200 LPM, and a flow rate setting of, for example, 2 LPM cannot be controlled by the MFC 51a. In particular, if the flow rate is set to 0 (zero) LPM, the supply valve 51b for purging inside the enclosure must be closed, and repeated ON / OFF of the valve is expected at the boundary of the concentration, and this repeating ON / OFF of the valve is also avoided.

[0061] Next, the oxygen concentration control inside the housing (control of the inert gas supply amount inside the housing) in which the control unit 1C performs the calculation processing of the above formula 1 to control the amount of inert gas supplied into the housing 2 will be explained with reference to the detailed flowchart shown in Figure 5 and the simple flowchart shown in Figure 6.

[0062] In the EFEM 1 of this embodiment, first, the control unit sets the total amount [T] of inert gas to be supplied into the housing 2 (total inert gas supply amount) using the inert gas total supply amount setting unit 11 (total inert gas supply amount setting step S1, see FIG. 6). Specifically, the control unit references the oxygen concentration control table and sets the total inert gas supply amount [T] based on the oxygen concentration inside the housing 2. At this time, the values ​​of [F], [G], and [H] in Equation 1, that is, the values ​​of the bottom purge inert gas supply amount to the FOUP 4 by the bottom purge device 36 of each load port 3, are cleared (set to a state where no numerical value is assigned).

[0063] Next, the control unit 1C determines, for each load port 3, whether the container door 43 of the FOUP 4 placed on the loading table of that load port 3 is open and whether the bottom purge process is being performed by the bottom purge device 36, using the door open / bottom purge determination unit 12 (door open / bottom purge determination step S2; corresponding to the "door open / purge determination step" of the present invention). The EFEM 1 of this embodiment performs the door open / bottom purge determination step S2 for all three load ports in turn.

[0064] If the determination result in the door open / bottom purge determination step S2 is YES, the control unit 1C causes the inert gas supply amount calculation unit 13 to calculate the amount of inert gas to be supplied into the housing 2 [A] based on the value obtained by subtracting the amounts of bottom purge inert gas [F], [G], and [H] supplied to the FOUP 4 by the bottom purge device 36 of the load port 3 from the total amount of inert gas supplied [T] (intra-housing inert gas supply amount calculation step S3). If the determination result in the door open / bottom purge determination step S2 is NO, the amount of bottom purge inert gas to be supplied [F] to the FOUP 4 by the bottom purge device 36 of the load port 3 (e.g., the first load port 3) is set to zero in the intra-housing inert gas supply amount calculation step S3, and the amount of inert gas to be supplied into the housing 2 [A] is calculated. FIG. 7 shows an example of an oxygen concentration control table in which, of the three load ports 3, the determination result of the door open / bottom purge determination unit 12 for the first load port 3 is Yes (the container door 43 of the FOUP 4 placed on the mounting table 35 is open and the bottom purge process is being performed by the bottom purge device 36), and the determination result of the door open / bottom purge determination unit 12 for the second and third load ports 3 is No.

[0065] Furthermore, in the inert gas supply amount calculation step S3 in the case where the inert gas supply devices in the transfer robot (ejector R8, transfer robot purging device R9) are in an inert gas supply state or the ionizer 8 is in an inert gas supply state, the inert gas supply amounts "C" and "D" of the inert gas supply devices in the transfer robot (ejector R8, transfer robot purging device R9) and the inert gas supply amount "E" of the ionizer 8 are also subtracted from the total inert gas supply amount [T] to calculate the inert gas supply amount into the housing 2. The oxygen concentration control table shown in Fig. 7 is for the case where the container door 43 of the FOUP 4 placed on the mounting table 35 of the first load port is in an open state and the bottom purge process is being performed by the bottom purge device 36 at a flow rate of 50 MLP. As can be seen from the figure, for example, when the oxygen concentration inside the enclosure 2 is 100 ppm, the total inert gas supply amount [T] is set to 310 LPM in the inert gas total supply amount setting step S1, and by performing a process in the enclosure inert gas supply amount calculation step S3 to subtract the bottom purge inert gas supply amount [F] (LPM) to the FOUP 4 by the bottom purge device 36 of the first load port 3, i.e.,

[50] (LPM), from the total inert gas supply amount

[0310] (LPM), the inert gas supply amount [A] into the enclosure 2 becomes a value that is reduced by 50 LPM compared to when bottom purge processing is not performed by the bottom purge devices 36 of all load ports 3 (Figure 4).

[0066] Next, the control unit 1C determines the calculation result of the inert gas supply amount calculation unit 13 as the inert gas supply amount command value [A] using the command value determination unit 14 (command value determination step S4). If the inert gas supply amount command value [A] determined in command value determination step S4 differs from the current inert gas supply amount command value (the current flow rate command value to the inert gas supply amount calculation unit 51a for inlet purging; [Acurrent], "current MFC command value" in FIG. 6), that is, if the difference exceeds the threshold value for switching the total inert gas supply amount [T] for the oxygen concentration specified in the oxygen concentration control table, the control unit 1C determines whether the difference has continued for "T1" seconds. "T1" is the time required to determine that the flow rate boundary has been stably exceeded, and in this embodiment, the default value of "T1" is set to 20 seconds. That is, when the current inert gas supply rate command value [Acurrent] differs from the inert gas supply rate command value [A] determined in command value determination step S4, if the current inert gas supply rate command value [Acurrent] differs from the inert gas supply rate command value [A] determined in command value determination step S4 continuously for "T1" seconds, it is determined that the flow rate boundary has been stably exceeded, and the command value of the MFC 51a for purging inside the enclosure is updated to the inert gas supply rate command value [A] determined in command value determination step S4. This is to avoid a situation in which the automatic pressure control becomes unstable due to a change in the inert gas flow rate caused by fluctuations in the oxygen concentration value at the boundary where the inert gas supply rate for each oxygen concentration is switched.

[0067] If the determination result indicates that the difference between the inert gas supply rate command value [A] and the current inert gas supply rate command value [Acurrent] has continued for "T1" seconds, the inert gas supply rate command value for the MFC 51a for purging the enclosure is updated, the update of the final inert gas supply rate command value is terminated, and flow rate control for the MFC 51a for purging the enclosure is performed based on the updated inert gas supply rate command value. The above procedure is then repeated until a predetermined time has elapsed or a predetermined processing completion time has elapsed. In this embodiment, when the inert gas supply rate command value is updated, that is, when the command value determined in command value determination step S4 is updated as the latest inert gas supply rate command value, the inert gas supply rate command value is gradually changed over a predetermined time. Specifically, after transitioning to the oxygen concentration-controlled transfer mode, the inert gas supply rate command value is updated at [F2] LPM / sec. When transitioning to the oxygen concentration-controlled transfer mode, the inert gas supply rate command value is updated at [F1] LPM / sec. In this embodiment, [F2] is set to a value relatively smaller than [F1], and the rate of change per second (LPM / sec) when updating the inert gas supply rate command value is set to a small value. As a result, after transitioning to the oxygen concentration-controlled transfer mode, the inert gas supply rate command value is changed more gradually than during transition to the oxygen concentration-controlled transfer mode. For example, when changing (updating) the inert gas supply rate command value from 200 LPM to 150 LPM after transitioning to the oxygen concentration-controlled transfer mode, that is, when decreasing the flow rate setting value for the MFC 51a for purging the enclosure 2 by 50 LPM, the flow rate is gradually changed by 2 LPM per second over a total of 25 seconds to prevent a sudden change in the pressure inside the enclosure 2, and the aperture of the exhaust valve of the exhaust pipe 22d is changed according to the inert gas supply rate.

[0068] As described above, according to the EFEM 1 of this embodiment, the amount of inert gas supplied into the housing 2 is set based on the oxygen concentration inside the housing 2. When the bottom purge process is being performed by the bottom purge device 36 with the container door 43 open (when the determination result of the door open / bottom purge determination unit 12 is YES), the amount of inert gas supplied for the bottom purge process (bottom purge inert gas supply amount) is subtracted from the total inert gas supply amount, and an inert gas supply amount command value, which is a command value for the amount of inert gas supplied into the housing 2, is determined based on the subtracted value. The amount of inert gas supplied into the housing 2 is then controlled based on the inert gas supply amount command value. This allows the amount of gas supplied to the entire EFEM 1 to be controlled so as not to exceed the upper limit (the total inert gas supply amount set based on the oxygen concentration inside the housing 2) by taking into account the amount of inert gas supplied during the bottom purge process. This avoids the waste of inert gas, which is the discharge of inert gas from the housing 2 even when the oxygen concentration has not changed, and makes it possible to constantly maintain a slightly positive pressure inside the housing 2 of the EFEM 1 at a specified usage amount while saving inert gas.

[0069] In particular, in the EFEM1 according to this embodiment, when the inert gas supply control into the housing 2 is being executed, when the inert gas supply amount into the housing 2 is changed to the inert gas supply amount command value determined based on the calculation result of the inert gas supply amount calculation unit 13 in the housing (when the inert gas supply amount command value determined based on the calculation result of the inert gas supply amount calculation unit 13 in the housing is updated as the latest inert gas supply amount command value), the amount is controlled to be changed gradually over a predetermined time, thereby preventing and suppressing sudden pressure changes inside the housing 2.

[0070] In addition, when the EFEM1 of this embodiment is configured to include an inert gas supply device (ejector R8, purge device R9 inside the transport robot) that supplies inert gas to the inside of the substrate transport robot R arranged in the substrate transport space 2Sa, or an ionizer 8 that discharges electricity from the substrate by locally supplying inert gas to the substrate placed at a predetermined location in the substrate transport space 2Sa, the inert gas supply amount command value is calculated and determined taking these inert gas supply amounts into consideration, so that it can be controlled so that the upper limit of the gas supply amount to the entire EFEM1 (the total inert gas supply amount set based on the oxygen concentration in the housing 2) is not exceeded, thereby avoiding waste of inert gas and making it possible to always maintain a slightly positive pressure inside the housing 2 of the EFEM1 with the specified usage amount.

[0071] Furthermore, as described above, the inert gas supply amount control method according to this embodiment is a method for controlling the amount of inert gas supplied into the housing 2 based on a command value determined through the total inert gas supply amount setting step S1, the door open / bottom purge determination step S2, the inert gas supply amount calculation step S3 inside the housing, and the command value determination step S4. Therefore, it is possible to avoid a situation in which more nitrogen gas than the initial control amount is supplied into the housing 2, and it is possible to conserve nitrogen gas while always maintaining the pressure inside the housing 2 of the EFEM1 at a slightly positive pressure at the specified usage amount.

[0072] Although the embodiments of the present invention have been described above, the present invention is not limited to the configurations of the above embodiments. For example, the parameters of the oxygen concentration control table shown in the above embodiments are merely examples, and the specific numerical values ​​and default values ​​of the parameters can be changed or selected as appropriate.

[0073] In the above-described embodiment, a FOUP is used as the substrate storage container. However, in the present invention, storage containers other than a FOUP, such as a MAC (Multi Application Carrier), an H-MAC (Horizontal-MAC), or a FOSB (Front Open Shipping Box), can also be used.

[0074] In the above embodiment, nitrogen gas is used as an example of the inert gas used in the bottom purge process, but the present invention is not limited to this, and any desired gas such as dry gas or argon gas can be used. In the above-described embodiment, a configuration in which three load ports are connected to the front wall of the transfer chamber is exemplified, but a configuration in which fewer than three or four or more load ports are connected can also be adopted.

[0075] Furthermore, the specific configuration of each part is not limited to the above embodiment, and various modifications are possible within the scope of the present invention. [Explanation of symbols]

[0076] 1...EFEM 11...Inert gas supply total amount setting unit 12...Door open / purge judgment unit (door open / bottom purge judgment unit) 13...Inner housing inert gas supply amount calculation unit 1C...Control unit 2. Housing 3. Loading port 36...Bottom purge device 4...Floor-up-type (FOUP) 8...Ionizer R...Substrate transport robot R8, R9...Inert gas supply device for transport robot (ejector, transport robot internal purge)

Claims

1. An EFEM comprising: a housing having a substantially closed substrate transfer space therein; a main gas supply means for supplying a gas into the housing through a predetermined supply path; another gas supply means for supplying the gas into the housing through at least one or more supply paths other than the predetermined supply path; and a control unit for controlling at least the supply of the gas into the housing, The control unit a total gas supply amount setting unit that sets a total supply amount of the gas to be supplied into the housing based on the oxygen concentration inside the housing; an in-casing gas supply amount calculation unit that calculates the amount of gas supplied into the casing by the main gas supply means based on a value obtained by subtracting the amount of gas supplied by the other gas supply means from the total gas supply amount set by the total gas supply amount setting unit when the gas is supplied from the other gas supply means through at least one of the supply paths, An EFEM characterized in that the amount of gas supplied into the housing by the main gas supply means is controlled based on a gas supply amount command value determined based on the calculation result of the housing gas supply amount calculation unit.

2. 2. The EFEM of claim 1, wherein the control unit is configured to gradually change the gas supply amount into the enclosure by the main gas supply means from the current gas supply amount command value to the latest gas supply amount command value over a predetermined period of time when controlling the gas supply amount into the enclosure by the main gas supply means based on the gas supply amount command value determined based on the calculation result of the gas supply amount calculation unit inside the enclosure.

3. A circulation path is formed inside the housing to circulate the gas that supplies the gas from the predetermined supply path to the circulation path, an FFU arrangement space in which a fan filter unit is disposed and which is connected to the predetermined supply path and sends the gas to the substrate transfer space; and a return path that sends the gas back from the substrate transfer space to the FFU arrangement space, and a fan that sucks the gas from the substrate transfer space is disposed in the return path.

3. The EFEM according to claim 1, wherein the circulation path is configured to include the substrate transfer space, the FFU arrangement space, and the return path.

4. a mounting table on which a substrate storage container can be placed; and a nozzle capable of supplying the gas into an internal space of the substrate storage container placed on the mounting table, connecting at least one supply path other than the predetermined supply path to the nozzle; The control unit 4. The EFEM according to claim 1, wherein, for each load port adjacent to the enclosure, when a container door of the substrate storage container placed on the mounting table is in an open state and the gas is being supplied through the nozzle, the gas supply amount calculation unit calculates the amount of gas supplied into the enclosure by the main gas supply means based on a value obtained by subtracting the amount of gas supplied through the nozzle from the total amount of inert gas supplied.

5. a substrate transfer robot disposed in the substrate transfer space; and a transfer robot internal gas supply device that supplies the gas to an interior of the substrate transfer robot, connecting at least one supply path other than the predetermined supply path to the gas supply device in the transfer robot; The control unit An EFEM as described in any one of claims 1 to 4, wherein when the gas supply device inside the transport robot is in a gas supply state, the gas supply amount calculation unit inside the housing calculates the gas supply amount into the housing based on a value obtained by subtracting the gas supply amount by the gas supply device inside the transport robot from the total gas supply amount.

6. an ionizer that locally supplies gas to a substrate placed at a predetermined location in the substrate transfer space to thereby eliminate static electricity from the substrate; At least one supply path other than the predetermined supply path is connected to the ionizer; 6. An EFEM according to any one of claims 1 to 5, wherein when the ionizer is in a gas supply state, the housing gas supply amount calculation unit calculates the amount of gas supplied into the housing based on a value obtained by subtracting the amount of gas supplied by the ionizer from the total amount of gas supplied.

7. A method for controlling a gas supply amount into an EFEM, the method comprising: a housing having a substantially closed substrate transfer space therein; a main gas supply means for supplying a gas into the housing through a predetermined supply path; another gas supply means for supplying the gas into the housing through at least one or more supply paths other than the predetermined supply path; and a control unit for controlling at least the supply of the gas into the housing, a total gas supply amount setting step for setting a total amount of gas to be supplied into the housing; and an in-casing gas supply amount calculation step of calculating, when the gas is supplied from the other gas supply means through at least one of the supply paths, the amount of gas supplied into the casing by the main gas supply means based on a value obtained by subtracting the amount of gas supplied by the other gas supply means from the total gas supply amount set in the total gas supply amount setting step, A gas supply amount control method, characterized in that the amount of gas supplied into the housing by the main gas supply means is controlled based on a gas supply amount command value determined based on the calculation result of the gas supply amount calculation step into the housing.

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