EFEM, Inert Gas Supply Control Method

Abstract

To provide an EFEM capable of keeping pressure inside a housing at a slightly positive pressure with a prescribed amount of use of nitrogen gas while avoiding wasteful use thereof.SOLUTION: A control section of an EFEM comprises: an inert gas supply total amount setting unit 11 setting a total amount of inert gas to be supplied into a housing 2 based on oxygen concentration inside the housing 2; a door-open and bottom-purge determination unit 12 determining, for each load port 3, whether or not a door of a FOUP 4 is in an open state and the housing is under bottom-purge processing using a bottom purge device 36; and an intra-housing inert gas supply amount calculation unit 13 calculating an inert gas supply amount into the housing 2 based on a value obtained by subtracting a bottom purge inert gas supply amount by the bottom purge device 36 of the load port 4 from the inert gas supply total amount when the determination result of the determination unit 12 is YES. The inert gas supply amount into the housing 2 is controlled in accordance with an inert gas supply amount command value determined based on a calculation result of the calculation unit 13.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to a control system and a control method for supplying an inert gas such as nitrogen gas into a housing which is an EFEM (Equipment Front End Module) used for automatic conveyance of a substrate, particularly a main body portion of the EFEM.

Background Art

[0002] In the semiconductor manufacturing process, in order to improve the yield and quality, the substrate is processed in a clean room. In recent years, a "mini-environment method" has been adopted to further improve the cleanliness only for a local space around the substrate, and means for performing substrate conveyance and other processes are employed. In the mini-environment method, a load port having a function of opening and closing the FOUP door in a state of being in close contact with the FOUP door (hereinafter referred to as "FOUP door") is provided adjacent to the housing, which forms a part of the wall surface of the housing having a substantially closed substrate conveyance space (hereinafter referred to as "conveyance space") inside, and a FOUP (Front-Opening Unified Pod), which is a container in which a substrate is stored in a highly clean internal space, is placed.

[0003] The load port is a device for taking in and out a substrate between the inside of the housing, and functions as an interface portion between the housing and the FOUP. When the door of the load port (hereinafter referred to as "load port door") which can engage with the FOUP door and open and close the FOUP door is opened, the substrate in the FOUP can be taken out into the housing or the substrate can be stored from the housing into the FOUP by a substrate conveyance robot arranged in the conveyance space inside the housing.

[0004] In the semiconductor manufacturing process, in order to appropriately maintain the atmosphere around the substrate, a storage pod called the above-mentioned FOUP is used, and the substrate is housed and managed inside the FOUP. In particular, in recent years, the high integration of elements and the miniaturization of circuits have been progressing, and it is required to maintain a high degree of cleanliness around the substrate so that particles and moisture do not adhere to the substrate surface. Therefore, in order to prevent the surface properties of the substrate from changing, such as oxidation of the substrate surface, the inside of the FOUP is filled with nitrogen gas, and a process (purge process) is also performed to make the atmosphere around the substrate a nitrogen gas atmosphere, which is an inert gas, or to make it a vacuum state.

[0005] In addition, an EFEM configured to be filled with nitrogen gas, which is an inert gas, inside the housing has been devised and put into practical use (for example, Patent Document 1). Specifically, this EFEM includes a circulation flow path including a transport space for circulating nitrogen gas inside the transport 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 appropriately supplied and discharged according to fluctuations in the oxygen concentration and the like in the circulation flow path. As a result, it is possible to keep the inside of the transport chamber in a nitrogen gas atmosphere while suppressing an increase in the supply amount of nitrogen gas compared to a configuration in which nitrogen gas is constantly supplied and discharged.

[0006] By the way, in the process of manufacturing next-generation semiconductor devices where miniaturization and multilayerization on the nanometer order are progressing, in order to improve the yield and quality stability of semiconductor devices, the substrate transport space is isolated from the external atmosphere, and an oxidation prevention and corrosion prevention effect is obtained in a high-purity nitrogen gas atmosphere (extremely low oxygen concentration and humidity). In order to meet such needs, it has become necessary to manage environmental items in the transport chamber, which have not been highly regarded in the past, at an even higher level. Specifically required levels are low humidity (for example, dew point humidity less than minus 50 degrees) and low oxygen concentration (for example, 100 ppm). In addition, with the miniaturization and multilayerization of semiconductors, the deterioration of substrates during semiconductor manufacturing has also become a problem. Harmful substances that deteriorate the substrate are released from the substrate after a certain period of time has passed since the treatment. Therefore, in recent years, not only the bottom purge process of placing a FOUP on a load port and purging nitrogen gas into the FOUP before opening the FOUP door, but also a configuration is adopted in which nitrogen gas is continuously supplied from a bottom purge nozzle to the substrate waiting in the FOUP even after the FOUP door is opened, in order to prevent and suppress the deterioration of the substrate during standby.

Prior Art Documents

Patent Documents

[0007]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0008] However, in a conventional EFEM, since the supply amount of nitrogen gas to the transfer chamber and the supply amount of nitrogen gas to the load port during the bottom purge process were controlled separately, when the FOUP door was opened and the bottom purge was continued with the FOUP docked to the housing, more nitrogen gas than the specified amount would flow into the housing, causing a problem that the pressure inside the housing would increase.

[0009] Also, although it is possible to exhaust the nitrogen gas inside the housing from the exhaust port when the pressure becomes higher than the preset value, exhausting only for the purpose of depressurization can be a waste of nitrogen gas even though there is no abnormality in the oxygen concentration or humidity.

[0010] The present invention has been made paying attention to such problems, and the main object is to provide an EFEM and an inert gas supply control method into the EFEM that can avoid waste of nitrogen gas and always maintain the pressure inside the housing at a slightly positive pressure with a specified usage amount. Note that the present invention is a technology that can also be applied to a substrate storage container other than a FOUP.

Means for Solving the Problems

[0011] That is, the present invention relates to an EFEM including a housing having a substantially closed substrate transfer space therein, and a control unit that controls at least the supply of an inert gas into the housing. And, in the EFEM according to the present invention, the control unit includes an inert gas total supply amount setting unit that sets the total supply amount of the inert gas supplied into the housing based on the oxygen concentration in the housing, and for each load port, when the container door of the substrate storage container placed on the placement table on which the substrate storage container can be placed is in an open state, and the purge process by a purge device capable of replacing the gas atmosphere in the substrate storage container placed on the placement table with an inert gas is in progress or not, a door open / purge determination unit that determines whether or not it is in progress, and when the determination result of the door open / purge determination unit is YES, the inert gas supply amount into the housing is calculated based on a value obtained by subtracting the supply amount of the inert gas into the substrate storage container by the purge device of the load port, which is the supply amount of the inert gas in the container, from the total supply amount of the inert gas set by the inert gas total supply amount setting unit, and the inert gas supply amount into the housing is controlled by an inert gas supply amount command value determined based on the calculation result of the inert gas supply amount calculation unit into the housing. This is a characteristic feature.

[0012] The inventor has adopted a novel and useful technical idea of controlling the supply amount of an inert gas (nitrogen gas as a main example) into the housing based on the purge execution status by the load port, thereby avoiding wasteful use of nitrogen gas and realizing an EFEM capable of always maintaining a slightly positive pressure in the transfer chamber of the EFEM at a specified usage amount.

[0013] That is, in the EFEM according to the present invention, when the supply amount of the inert gas into the housing is set based on the oxygen concentration in the housing and the purge process by the purge device is executed with the container door open (when the determination result of the door open purge determination unit is YES), the supply amount of the inert gas used for the purge process (the supply amount of the inert gas in the container) is subtracted from the total supply amount of the inert gas, and based on the subtracted value, an inert gas supply amount command value, which is the command value of the supply amount of the inert gas into the housing, is determined, and the supply amount of the inert gas into the housing is controlled based on the inert gas supply amount command value. Thereby, considering the supply amount of the inert gas used during the execution of the purge process, it is possible to control so as not to exceed the upper limit of the gas supply amount to the entire EFEM (the total supply amount of the inert gas set based on the oxygen concentration in the housing), avoid the wasteful use of the inert gas, such as discharging the inert gas from the housing even though the oxygen concentration has not changed, and save the inert gas while always maintaining the pressure in the housing of the EFEM at a slightly positive pressure with a specified usage amount.

[0014] In particular, in the EFEM according to the present invention, when changing the supply amount of the inert gas into the housing to the inert gas supply amount command value determined based on the calculation result of the in-housing inert gas supply amount calculation unit during the execution of the inert gas supply control into the housing (when updating the inert gas supply amount command value determined based on the calculation result of the in-housing inert gas supply amount calculation unit as the latest inert gas supply amount command value), by controlling to gradually change it over a predetermined time, a rapid pressure change in the housing can be prevented and suppressed.

[0015] When the EFEM according to the present invention is configured to include an inert gas supply device inside a substrate transfer robot that supplies an inert gas inside the substrate transfer robot disposed in a substrate transfer space, or is configured to include an ionizer that discharges static electricity from a substrate by locally supplying an inert gas to the substrate placed at a predetermined location in the substrate transfer space, it is preferable to calculate and determine an inert gas supply amount command value in consideration of these inert gas supply amounts. Specifically, when the inert gas supply device inside the transfer robot is in an inert gas supply state, the inert gas supply amount calculation unit inside the housing 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 inside the transfer robot and the inert gas supply amount inside the container from the total inert gas supply amount set by the total inert gas supply amount setting unit. Or when the ionizer is in an inert gas supply state, it is preferable to configure the inert gas supply amount calculation unit inside the housing to calculate 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 inside the container from the total inert gas supply amount set by the total inert gas supply amount setting unit.

[0016] Further, the 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 control unit that controls the supply of inert gas into the housing. The method includes an inert gas total supply amount setting step of setting the total supply amount of the inert gas supplied into the housing based on the oxygen concentration in the housing, and for each load port adjacent to the housing, determining whether the container door of the substrate storage container placed on the mounting table on which the substrate storage container of the load port can be placed is in an open state and whether the purge process by the purge device is in progress, which is a door open / purge determination step. When the determination result of the door open / purge determination unit is YES, based on the value obtained by subtracting the in-container inert gas supply amount, which is the amount of inert gas supplied into the substrate storage container by the purge device of the load port, from the total supply amount of the inert gas set in the inert gas total supply amount setting step, an in-housing inert gas supply amount calculation step of calculating the amount of inert gas supplied into the housing is performed. Based on the calculation result in the in-housing inert gas supply amount calculation step, the amount of inert gas supplied into the housing is controlled.

[0017] With such an inert gas supply amount control method according to the present invention, the same operational effects as those of the EFEM according to the present invention described above can be obtained, and a situation where an inert gas amount exceeding the initial control amount is supplied into the housing can be avoided. As a result, an increase in the pressure inside the housing can be prevented, and problems caused by supplying an excessive amount of inert gas, that is, the problem of wasteful use of inert gas by discharging the inert gas despite no change in the oxygen concentration, can be solved, and the inert gas can be saved.

Effects of the Invention

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

Brief Description of the Drawings

[0019]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Embodiments for Carrying Out the Invention

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

[0021] As shown in FIG. 1, the EFEM1 (Equipment Front End Module) according to this embodiment includes a housing 2, which is a main body disposed in a clean room, and a load port 3 in a semiconductor manufacturing process. FIG. 1 schematically shows the relative positional relationship between the EFEM1 and its peripheral devices. The FOUP4 shown in the figure is a kind of "substrate storage container" in the present invention and is used together with the EFEM1.

[0022] A processing device M (semiconductor processing device) is provided adjacent to the rear wall 2b of the housing 2 facing the front wall 2a where the load port 3 is disposed. That is, the load port 3 is connected to the opening provided in the front wall 2a of the housing 2, and the processing device M is connected to the opening provided in the rear wall 2b, thereby forming a substantially closed space (substrate transfer space 2Sa, FFU arrangement space 2Sb) inside the housing 2.

[0023] In the clean room, the internal space MS of the processing device M, the substrate transfer space 2Sa and the FFU arrangement space 2Sb, which are the internal spaces of the housing 2, and the internal space 4S of the FOUP4 placed on the load port 3 are maintained at a high cleanliness level.

[0024] In this embodiment, as shown in FIG. 1, the load port 3, the housing 2, and the processing device M are arranged in close proximity to each other in this order in the front-rear direction X of the EFEM1. The operation of the EFEM1 is controlled by a controller of the entire EFEM1 (control unit 1C shown in FIG. 1) and a controller of the load port 3 (control unit 3C shown in FIG. 1), and the operation of the processing device M is controlled by a controller of the processing device M (control unit MC shown in FIG. 1). Here, the control unit MC, which is the controller of the entire processing device M, and the control unit 1C, which is the controller of the entire EFEM1, are higher-level controllers of the control unit 3C of the load port 3. Each of these control units 1C, 3C, and MC is composed of a normal microprocessor or the like equipped with a CPU, a memory, and an interface. The memory stores programs necessary for processing in advance. The CPU sequentially retrieves and executes the necessary programs and cooperates with peripheral hardware resources to realize the intended functions.

[0025] In the substrate transfer space 2Sa, which is the internal space of the housing 2, a substrate transfer robot R capable of transferring the substrate W (semiconductor wafer) between the FOUP 4 and the processing apparatus M is provided (see FIG. 1). In the FFU arrangement space 2Sb, which is the space above the substrate transfer space 2Sa in the internal space of the housing 2, an FFU 23 (fan filter unit) is provided. By driving the FFU 23, a downward airflow is generated in the substrate transfer space 2Sa of the housing 2, and an inert gas (environmental gas) such as nitrogen gas, which is a highly clean gas, can be circulated 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 the 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 rises through the return path 22, and is set to return to the FFU installation space 2Sb.

[0026] The FFU 23 removes particles contained in the nitrogen gas by a filter while sending the nitrogen gas in the FFU installation space 2Sb downward by a fan. The purified nitrogen gas is sent from the FFU installation space 2Sb to the substrate transfer space 2Sa to form 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 the present embodiment, the nitrogen gas is sucked into the return path 22 by a fan 22b provided above the opening 22a and sent upward to return to the FFU installation space 2Sb. The nitrogen gas returned to the FFU installation space 2Sb is purified by the FFU 23 and sent to the substrate transfer space 2Sa again. Note that the return path 22 is a path isolated from the substrate transfer space 2Sa and the FFU installation space 2Sb by a partition wall 22c (an appropriate support wall or the like), and only the opening 22a formed at the lower end of the return path 22 communicates with the substrate transfer space 2Sa, and only the upper end of the return path 22 communicates with the FFU installation space 2Sb.

[0027] With the above configuration, it is possible to circulate nitrogen gas in the circulation path 21. A supply path 51 for supplying nitrogen gas into the circulation path 21 is connected to the side portion of the FFU installation space 2Sb. As shown in FIG. 2, the supply path 51 is connected to a nitrogen gas supply source 50. At a predetermined location of the supply path 51, an MFC51a (Mass Flow Controller) for measuring and controlling the flow rate of the supply path 51, which is a gas flow path, and a supply valve 51b capable of changing the gas supply amount per unit time are provided. In the present embodiment, a sub-supply path 52 branching from a predetermined location on the upstream side of the MFC51a and the supply valve 51b in the supply path 51 is set, and the sub-supply path 52 is connected to a predetermined location on the downstream side of the MFC51a and the supply valve 51b in the supply path 51. At a predetermined location of the sub-supply path 52, a supply valve 52b for switching the supply ON / OFF of nitrogen gas is provided. Note that "FM" shown in FIG. 2 is a flow meter 52a (Flow Meter). Therefore, in the present embodiment, a part of the gas supply amount into the circulation path 21 can be borne by the gas supply amount through the sub-supply path 52. In the present embodiment, the supply source of the supply path 51 is configured to be switchable between the above-described nitrogen gas supply source 50 and a CDA (Clean Dry Air) supply source shown in FIG. 2. The lowercase Roman numerals shown in FIG. 1 are used in the sense of being continuous with the same lowercase Roman numerals shown in FIG. 2.

[0028] Also, as shown in FIG. 1, a discharge pipe 22d for discharging the gas in the circulation path 21 is connected to the front end of the substrate transfer space 2Sa. The discharge pipe 22d communicates with the external space. At a predetermined position of the discharge pipe 22d, a discharge valve is provided which is controlled according to the pressure of the housing 2 and can change the discharge amount of the gas in the circulation path 21 per unit time. Thereby, it becomes possible to execute a process (also referred to as an in-chamber purge process or an EFEM purge process) of appropriately supplying and discharging nitrogen gas to and from the circulation path 21 to adjust the oxygen concentration in the internal space of the housing 2. For example, when the oxygen concentration in the circulation path 21 rises, a large amount of nitrogen gas is temporarily supplied to the circulation path 21 from the supply source 50 via the supply path 51 (including the sub-supply path 52), and oxygen is discharged together with the nitrogen gas through the discharge pipe 22d, so that the oxygen concentration can be lowered. The control unit 1C is electrically connected to an oxygen concentration meter 2e, a pressure meter 2f, a humidity meter 2g, etc. installed in the housing 2, and receives the measurement results of these measuring devices to grasp information regarding the atmosphere in the housing 2 (in FIG. 1, for convenience of explanation, the oxygen concentration meter 2e, the pressure meter 2f, and the humidity meter 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 main body 42 whose internal space 4S can be opened only rearward through the transfer entrance 41, and a FOUP door 43 (corresponding to the "container door 43" of the present invention) that can open and close the transfer entrance 41. The FOUP 4 is a known one in which multi-stage slots are provided inside, and substrates W to be transferred can be accommodated in each slot, and these substrates W can be taken in and out through the transfer entrance 41. A flange portion 44 to be gripped by a device (for example, OHT: Over Head Transport) for automatically transporting the FOUP 4 is provided on the upward-facing surface of the FOUP main body 42. The FOUP 4 is placed on the mounting table 35 of the load port 3. A port (not shown) is provided on the bottom wall of the FOUP main body 42. The port mainly consists of, for example, a hollow cylindrical grommet seal fitted into a port mounting through hole formed in the bottom wall of the FOUP main body 42, and is configured to be openable and closable by a check valve.

[0030] As shown in Fig. 1, the load port 3 according to this embodiment constitutes a part of the front wall 2a of the housing 2, and includes a plate-shaped frame 32 in which an opening 31 for opening the internal space (substrate transfer space 2Sa) of the housing 2 is formed, a load port door 33 for opening and closing the opening 31 of the frame 32, a door opening and closing mechanism 34 for moving the load port door 33 to a door open position where it retreats to the housing 2 side to open the opening 31 of the frame 32, and a mounting table 35 provided on the frame 32 in a substantially horizontal posture.

[0031] The frame 32 is arranged in an upright posture and is a substantially rectangular plate having an opening 31 sized to communicate with the transfer inlet / outlet 41 of the FOUP 4 placed on the mounting table 35. Fig. 1 schematically shows the opening 31 of the frame 32.

[0032] The mounting table 35 is provided on the upper part of a horizontal base 351 (support base) arranged in a substantially horizontal posture at a position slightly above the center in the height direction of the frame 32, and can mount the FOUP 4 in a direction such that the FOUP door 43 for opening and closing the internal space 4S of the FOUP main body 42 faces the load port door 33. Further, the mounting table 35 is configured to be able to move forward and backward with respect to the frame 32 between a predetermined docking position where the FOUP door 43 approaches the opening 31 of the frame 32 and a position where the FOUP door 43 is separated from the frame 32 by a predetermined distance from the docking position (see Fig. 1). In this embodiment, in the front-rear direction X (see Fig. 1 etc.) in which the FOUP 4 placed 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 between a fully closed position where the opening 31 of the frame 32 is sealed while maintaining the engagement state with the FOUP door 43 by the door opening / closing mechanism 34, a door open position retracted toward the housing 2 side from the fully closed position, and a fully open position where 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 arranged at positions overlapping the return path 22 of the circulation path 21 in a side view. However, actually, 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 a space formed between the circulation paths 21 arranged side by side in the width direction and communicating with the substrate transfer space 2Sa. Therefore, the load port door 33 does not move in the return path 22 together with the FOUP door 43.

[0034] The load port 3 of the present embodiment includes a bottom purge device 36 (corresponding to the "purge device" of the present invention) that can inject a purge gas composed 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 includes a plurality of purge nozzles 37 (gas supply and discharge devices) arranged at predetermined positions on the mounting table 35 in a state where the upper end portions can be exposed. These plurality of purge nozzles 37 are attached at appropriate positions on the mounting table 35 according to the positions of the ports provided on the bottom surface of the FOUP 4 and can be connected in contact with the ports. The bottom purge process (corresponding to the "purge process" of the present invention) using such a bottom purge device 36 functions a predetermined number (excluding all) of the plurality of ports provided at the bottom of the FOUP 4 as "supply ports", injects an appropriately selected purge gas such as nitrogen gas, inert gas, or dry air into the FOUP 4 through the purge nozzles 37 connected to the supply ports, and functions the remaining ports as "exhaust ports", and discharges the gas atmosphere in the FOUP 4 through the purge nozzles 37 connected to the exhaust ports, so as to fill the FOUP 4 with the purge gas. Each load port 3 includes 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 supply source 60 of nitrogen gas for bottom purge processing. Note that "LP Purge" in FIG. 2 means load port purge, indicating that the supply source 60 is the supply source of nitrogen gas used for bottom purge processing. At a predetermined location of the supply path 61, an MFC61a (Mass Flow Controller) for measuring and controlling the flow rate of the supply path 61, which is a gas flow path, and a supply valve 61b capable of changing the gas supply amount per unit time are provided. Further, an exhaust pipe (not shown) for discharging the gas in the FOUP 4 is connected to the purge nozzles connected to the exhaust ports.

[0035] As shown in FIG. 1, the substrate transfer robot R has a base portion R1 fixed in a substrate transfer space 2Sa, and an arm R2 whose base end is rotatably supported by the base portion R1. The arm R2 is a multi-joint robot in which a plurality of arm elements R3, R4, R5 and a hand R6 constituting the arm R2 are sequentially rotatably connected. The arm R2 of the present embodiment has three arm elements R3, R4, R5 and two (two-stage) hands R6. By rotating the arm elements R3, R4, R5, the hand R6 that holds the substrate W is horizontally moved. 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 below. Specifically, the base end of the lowermost arm element R3 is rotatably connected to the base portion R1, the base end of the middle arm element R4 is rotatably connected to the tip of the lowermost arm element R3, and the base end of the uppermost arm element R5 is rotatably connected to the tip of the middle arm element R4. The robot hand R6 is rotatably connected to the tip of the uppermost arm element R5.

[0036] The internal spaces R3a, R4a, R5a of the respective arm elements R3, R4, R5 communicate with each other through a predetermined gap. By operating the mechanical components such as the cylinder R7 built in the robot hand R6, the substrate W can be held by the robot hand R6. The rod of the cylinder R7 (not shown) is configured to be extendable and contractible in a predetermined direction by the supply of nitrogen gas from a supply source (not shown) different from the above-described supply source 50.

[0037] EFEM1 is provided with an ejector R8 inside the substrate transfer robot R to suck and remove particles generated by the operation of the cylinder R7. Then, by supplying nitrogen gas from the supply source 50 to the ejector R8 through the supply path 53, the particles generated by the operation of the mechanical components such as the cylinder are sucked through the suction path 531. The nitrogen gas supplied to the ejector R8 flows together with the sucked particles through an appropriate path (connection path R12 described later) and is sent out to the return path 22. That is, the nitrogen gas flows into the circulation path 21 without being directly discharged to the external space of the housing 2. In this way, the particles generated near the cylinder R7 are sucked by the ejector R8, and the nitrogen gas supplied from the supply source 50 is discharged to the return path 22 together with the particles, so the nitrogen gas circulates as it is. Furthermore, the particles are removed by the FFU23. Therefore, compared with the configuration that performs vacuum exhaust, an increase in cost due to the replenishment of nitrogen gas can be suppressed. In the present embodiment, the supply source 50 that supplies nitrogen gas to the ejector R8 is made 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 53a for switching the supply ON / OFF of nitrogen gas is provided at a predetermined location on the supply path 53 to the ejector R8. Note that "FM" shown in FIG. 2 is a flow meter 53a. The supply path 53 to the ejector R8 branches from a predetermined location upstream of the MFC51a and the supply valve 51b among the supply paths 51 that function as the gas supply paths during the purge process inside the housing described above.

[0038] Also, a delivery port R11 for sending nitrogen gas to the circulation path 21 is formed at a predetermined position of the base portion R1 of the transfer robot R, and the delivery port R11 is connected to the return path 22 by a connection path R12. A fan R13 that is rotationally driven at a constant rotational speed is provided in the vicinity of the delivery port R11. The EFEM1 of the present embodiment includes a supply path 54 that passes through the internal space R1a of the base portion 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 arranged 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, and subsequently 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 portion R1 in this order, and is sent out to the return path 22 through the delivery port R11 of the base portion R1. Thereby, the gas in the internal space of the transfer robot R (the internal space R1a of the base portion R1 and the internal spaces R3a, R4a, and R5a of the arm elements R3, R4, and R5) can be replaced with an inert gas such as nitrogen gas.

[0039] Thus, since the EFEM 1 of this embodiment is provided with an in-robot purge device R9 that replaces the gas in the internal spaces of the transfer robot R (the internal space R1a of the base portion 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, even if particles are generated in the internal spaces of the transfer robot R (the internal space R1a of the base portion R1 and the internal spaces R3a, R4a, and R5a of the arm elements R3, R4, and R5), it is possible to suppress the leakage of these particles into the substrate transfer space 2Sa. Further, the particles discharged into the return path 22 are removed by the FFU 23 disposed on the downstream side of the return path 22. Therefore, it is possible to suppress the contamination of the substrate transfer space 2Sa by the particles generated in the internal spaces of the substrate transfer robot R (the internal space R1a of the base portion 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 in-robot purge device R9 is made 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 for switching the supply ON / OFF of nitrogen gas is provided at a predetermined location on the supply path 54. The supply path 54 to the in-robot purge device R9 branches from a predetermined location upstream of the MFC 51a and the supply valve 51b among the supply paths 51 that function as gas supply paths during the above-described in-chassis purge process.

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

[0041] As shown in Fig. 1, the EFEM1 of this embodiment detects the amount of deviation of the substrate W held by the arm R2 of the transfer robot R from the target holding position with respect to the holding position of the substrate W, and installs an aligner 7 for performing position correction (alignment) to correct the positional deviation in the substrate transfer space 2Sa. The aligner 7 includes an alignment table 71 on which the substrate W to be aligned is placed, and a through hole 73 formed in the side wall of an alignment case 72 having a mechanism for rotationally driving 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, and when the fan 75 is rotationally driven, the gas in the alignment case 72 is configured to be discharged toward the connection path 74 together with the particles generated in the alignment case 72.

[0042] The EFEM1 of this embodiment includes an ionizer 8 that blows nitrogen gas, which is ionized air, onto the substrate placed on the alignment table 71 from above. The ionizer 8 is connected to a supply path 55 through which an inert gas supplied from a supply source 50 flows, and by blowing the inert gas (ionized air) supplied from the supply source 50 onto the substrate W placed on the alignment table 71, the static electricity charged on the substrate W can be neutralized and removed (static elimination). In this embodiment, as shown in Fig. 2, the supply source 50 that supplies nitrogen gas to the ionizer 8 is made 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 55b for switching the supply ON / OFF of nitrogen gas is provided at a predetermined location 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 from a predetermined location upstream of the MFC 51a and the supply valve 51b among the supply paths 51 that function as gas supply paths during the above-described purge process inside the housing.

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

[0044] In the load port 3 of the present embodiment, when the FOUP 4 is placed at the normal position on the mounting table 35, it is detected that the pressed portion of, for example, a pressure sensor provided on the mounting table 35 is pressed by the bottom surface portion of the FOUP 4. Triggered by this, the purge nozzles 37 (all the purge nozzles 37) provided on the mounting table 35 protrude upward from the upper surface of the mounting table 35 and are connected to the respective ports of the FOUP 4, and each port switches from the closed state to the open state. Then, the load port 3 of the present embodiment performs a process (bottom purge process) of supplying nitrogen gas to the internal space 4S of the FOUP 4 by the bottom purge device 36 to replace the internal space 4S of the FOUP 4 with nitrogen gas. During the bottom purge process, the gas atmosphere inside the FOUP 4 is discharged outside the FOUP 4 from the purge nozzle 37 connected to the port that functions as an exhaust port. By such a bottom purge process, the moisture concentration and oxygen concentration inside the FOUP 4 are each reduced to a predetermined value or less, and the ambient environment around the substrate W inside the FOUP 4 is made into a low humidity environment and a low oxygen environment. The supply amount of nitrogen gas to the internal space 4S of the FOUP 4 during the bottom purge process can be changed by the bottom purge MFC 61a, and the supply flow rate of nitrogen gas can be changed according to the moisture concentration and oxygen concentration inside the FOUP 4.

[0045] After the locking process, the load port 3 of the present embodiment moves the mounting table 35 shown in FIG. 1 to a predetermined docking position, thereby bringing the FOUP door 43 into close contact with 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 transfer port 41 of the FOUP 4, and a process (door open process) for releasing the sealed state inside the FOUP 4 is executed. By executing the door open process, the internal space 4S of the FOUP main body 42 communicates with the substrate transfer space 2Sa of the housing 2, and the substrate transfer robot R provided in the substrate transfer space 2Sa of the housing 2 takes out the substrate W from the slot of the FOUP main body 42 or stores the substrate W in a specific slot (transfer process).

[0046] When all the substrates W in the FOUP 4 of the present embodiment have completed the processing steps by the processing apparatus M, the load port door 33 is moved to the fully closed position by the door drive mechanism 34, the opening 31 of the frame 32 and the transfer port 41 of the FOUP 4 are closed, and a process (door close process) for sealing the internal space 4S of the FOUP 4 is executed. By the above process, the opening 31 of the frame 32 and the transfer port 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 is in a sealed state.

[0047] Subsequently, the load port 3 of the present embodiment moves the mounting table 35 in a direction away from the frame 32 to release the state of locking the FOUP 4. As a result, the FOUP 4 storing the substrate W that has completed a predetermined process is delivered from the mounting table 35 of each load port 3 to the container transfer device and carried out to the next process.

[0048] In the EFEM 1 according to this embodiment that goes through such an operation flow, by continuously performing the bottom purge process that is executed before the door open process even after the door open process, it is possible to prevent and suppress the deterioration of the substrate waiting in the FOUP 4. On the other hand, by continuously performing the bottom purge process even after the door open process, nitrogen gas, which is the purge gas, may flow into the housing 2 from the FOUP 4, and there is a risk that the pressure in the housing 2 will increase. To avoid such a situation, the EFEM 1 according to this embodiment is configured such that the control unit 1C controls the amount of inert gas supplied into the housing 2. Specifically, it is configured such that the control unit 1C controls the amount of inert gas supplied into the housing 2 based on the 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), a housing internal inert gas supply amount calculation unit 13, and a command value determination unit 14.

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

[0051] The door open and bottom purge determination unit 12 determines, for each load port 3, whether or not the container door 43 of the FOUP 4 placed on the mounting table 35 of the load port 3 is in an open state and bottom purge processing by the bottom purge device 36 is in progress. Whether or not the container door 43 of the FOUP 4 is in an open state can be determined by an appropriate sensor (for example, a U-shaped microphoto sensor, etc.) provided near the container door 43 of the FOUP 4 among the load ports 3, and whether or not bottom purge processing by the bottom purge device 36 is in progress 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 the present embodiment includes three load ports 3, the determination process by the door open and bottom purge determination unit 12 is performed for each load port 3 (performed three times in total).

[0052] When the determination result of the door open / bottom purge determination unit 12 is YES, the inert gas supply amount calculation unit 13 in the housing calculates the inert gas supply amount into the housing 2 based on a value obtained by subtracting the bottom purge inert gas supply amount to the FOUP 4 by the bottom purge device 36 of the load port 3 (corresponding to the "inert gas supply amount in the container" of the present invention) from the inert gas supply amount set by the total inert gas supply amount setting unit 11. The bottom purge inert gas supply amount to the FOUP 4 by the bottom purge device 36 is a value that varies according to the oxygen concentration in the FOUP 4, the bottom purge treatment duration, etc., and that value (bottom purge inert gas supply amount) is based on the command value of the MFC 61a for bottom purge. Therefore, by specifying the command value of the MFC 61a for bottom purge by appropriate means, the bottom purge inert gas supply amount to the FOUP 4 by the bottom purge device 36 can be specified, and the specified value can be used in the calculation process in the inert gas supply amount calculation unit 13 in the housing. Further, 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 mounting table 35 of the load port 3 is in the closed state, or when the bottom purge process by the bottom purge device 36 is not being executed), the value subtracted from the total inert gas supply amount set by the total inert gas supply amount setting unit 11 is zero (the bottom purge inert gas supply amount to the FOUP 4 by the bottom purge device 36 of the load port 3 is zero), and the inert gas supply amount into the housing 2 is calculated.

[0053] Furthermore, when the inert gas supply device in the transfer robot is in the inert gas supply state, the inert gas supply amount calculation unit 13 in the housing subtracts 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 the present embodiment, the ejector R8 and the purge device R9 in the transfer robot respectively correspond to the inert gas supply device in the transfer robot. When the ejector R8 is in the inert gas supply state, the inert gas supply amount calculation unit 13 in the housing subtracts 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, or when the purge device R9 in the transfer robot is in the inert gas supply state, the inert gas supply amount calculation unit 13 in the housing subtracts the inert gas supply amount of the purge 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] Also, in the present embodiment, when the ionizer 8 is in the inert gas supply state, the inert gas supply amount calculation unit 13 in the housing subtracts the inert gas supply amount of the ionizer 8 from the total inert gas supply amount to calculate the inert gas supply amount into the housing 2.

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

[0056] The command value determination unit 14 determines the calculation result of the inert gas supply amount calculation unit 13 inside the housing as the inert gas supply amount command value into the housing 2. In the present embodiment, when changing (updating) the inert gas supply amount into the housing 2 to the inert gas supply amount command value determined based on the calculation result of the inert gas supply amount calculation unit 13 inside 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), it is configured to gradually change from the current inert gas supply amount command value to the latest inert gas supply amount command value over a predetermined time.

[0057] When the EFEM1 of the present embodiment is started with the power ON, it enters the maintenance mode for performing the air replacement process inside the housing 2. In this maintenance mode, air replacement is performed so that the oxygen concentration inside the housing 2 changes from less than 19.5% to 19.5% or more. The EFEM1 shifts from the maintenance mode to the transfer mode, and further shifts from the transfer mode to the transfer mode with oxygen concentration control. In the transfer mode with oxygen concentration control, inert gas supply control (oxygen concentration control inside the housing) by the control unit is performed.

[0058] When the shift to the transfer mode with oxygen concentration control starts, the EFEM1 monitors the numerical value of the oxygen concentration meter 2e provided at an appropriate location inside the housing 2 and controls it so that the oxygen concentration becomes 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 every second, the following calculation process according to Equation 1 is performed according to the oxygen concentration, and according to the calculation result, the inert gas supply amount into the housing 2, which is the control target, specifically, the flow rate setting to the MFC 51a for purging inside the housing provided at a predetermined location on the supply path 51 for supplying nitrogen gas into the circulation path 21 of the housing 2 is performed. A (LPM) = T - (B + C + D + E + F + G + H) ··· Equation 1 Here, A to H in Formula 1 are synonymous with A to H in the oxygen concentration control table of FIG. 4. A is the supply amount of inert gas (EFEM MFC Purge) into the housing 2 to be controlled, specifically, the flow rate command value to the housing internal purge MFC 51a, and the unit is LPM; liter / minute. T is the total supply amount of inert gas (total N2 supply amount (LPM)) into the housing 2 preset according to the oxygen concentration in the housing 2. Further, B, C, D, and E in Formula 1 are the supply amounts of main purge inert gas (Main Purge (LPM)), ejector inert gas (Robot Ejector (LPM)), transfer robot inner purge inert gas (Robot Inner Purge (LPM)), and ionizer inert gas (Ionizer Purge (LPM)), respectively. F, G, and H in Formula 1 are the supply amounts of inert gas (LP-1 MFC Purge (LPM), LP-2 MFC Purge (LPM), LP-3 MFC Purge (LPM)) of the bottom purge device 36 of the first load port, the second load port, and the third load port, respectively. The N and T columns in the oxygen concentration control table are individual parameters, and the B to E columns are parameters for each column. An example of default values is shown in the oxygen concentration control table of FIG. 3.

[0060] In this embodiment, when "A < 5", the flow rate setting to the housing internal purge MFC 51a is set to 5 LPM. This is because the control range of the housing internal purge MFC 51a is 4 to 200 LPM, and for example, a flow rate setting of 2 LPM cannot be controlled by the MFC 51a. In particular, when the flow rate is set to 0 (zero) LPM, it is necessary to close the housing internal purge supply valve 51b, and it is expected that the valve ON / OFF will be repeated at the concentration boundary. This is also to avoid such repeated valve ON / OFF.

[0061] Next, regarding the control of the oxygen concentration inside the housing (control of the supply amount of inert gas inside the housing) in which the control unit 1C performs the arithmetic processing of Formula 1 to control the supply amount of inert gas into the housing 2, it will be described with reference to the detailed flowchart shown in FIG. 5 and the simple flowchart shown in FIG. 6.

[0062] In the EFEM1 of this embodiment, first, the control unit sets the total amount [T] (inert gas supply total amount) of the inert gas supplied into the housing 2 by the inert gas supply total amount setting unit 11 (inert gas supply total amount setting step S1, see FIG. 6). Specifically, referring to the oxygen concentration control table, the total amount [T] of the inert gas supply is set based on the oxygen concentration in 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 amounts to the FOUP 4 by the bottom purge devices 36 of each load port 3 are cleared (set to a state where no numerical value is given).

[0063] Next, the control unit 1C determines, by the door open / bottom purge determination unit 12, for each load port 3 whether the container door 43 of the FOUP 4 placed on the mounting table of the load port 3 is in an open state and whether the bottom purge process by the bottom purge device 36 is in progress (door open / bottom purge determination step S2; corresponding to the "door open / purge determination step" of the present invention). In the EFEM1 of this embodiment, the door open / bottom purge determination step S2 is performed in order for all three load ports.

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

[0065] Furthermore, in the inert gas supply amount calculation step S3 inside the housing, when the inert gas supply devices (ejector R8, purge device R9 inside the transfer robot) inside the transfer robot are in the inert gas supply state, or when the ionizer 8 is in the inert gas supply state, the inert gas supply amounts "C", "D" of the inert gas supply devices (ejector R8, purge device R9 inside the transfer robot) 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 the open state and the bottom purge process is being executed at a flow rate of 50 MLP by the bottom purge device 36. As can be understood from the figure, for example, when the oxygen concentration inside the housing 2 is 100 ppm, the total inert gas supply amount [T] is set to 310 LPM in the total inert gas supply amount setting step S1, and in the inert gas supply amount calculation step S3 inside the housing, the total inert gas supply amount

[0310] (LPM) is subtracted from the bottom purge inert gas supply amount [F] (LPM), that is,

[50] (LPM) to the FOUP 4 by the bottom purge device 36 of the first load port 3. By performing this subtraction process, compared with the case where the bottom purge process by the bottom purge devices 36 of all the load ports 3 is not being executed (FIG. 4), the inert gas supply amount [A] into the housing 2 becomes a value decreased by 50 LPM.

[0066] Next, the control unit 1C determines, by the command value determination unit 14, the calculation result of the in-chamber inert gas supply amount calculation unit 13 as the inert gas supply amount command value [A] (command value determination step S4). When the inert gas supply amount command value [A] determined in the command value determination step S4 is different from the current inert gas supply amount command value (the current flow rate command value to the in-chamber purge MFC 51a; [Acurrent], "current MFC command value" in FIG. 6), that is, when the switching boundary value of the total inert gas supply amount [T] with respect to the oxygen concentration defined in the oxygen concentration control table is exceeded, it is determined whether or not the different state has continued for "T1" seconds. "T1" is the time for determining 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 amount command value [Acurrent] is different from the inert gas supply amount command value [A] determined in the command value determination step S4, if the current inert gas supply amount command value [Acurrent] and the inert gas supply amount command value [A] determined in the command value determination step S4 are different continuously for "T1" seconds, it is determined that the flow rate boundary has been stably exceeded, and the command value of the in-chamber purge MFC 51a is updated to the inert gas supply amount command value [A] determined in the command value determination step S4. This is to avoid a situation in which the automatic pressure control becomes unstable as the inert gas flow rate changes due to fluctuations in the oxygen concentration value at the switching boundary of the inert gas supply amount with respect to the oxygen concentration.

[0067] When the determination result is that the state where the inert gas supply amount command value [A] is different from the current inert gas supply amount command value [Acurrent] continues for "T1" seconds, update the inert gas supply amount command value to the purge MFC51a inside the housing, end the update of the final inert gas supply amount command value, perform flow control on the purge MFC51a inside the housing based on the updated inert gas supply amount command value, and thereafter, repeat the above procedure until a predetermined time has elapsed or a predetermined process is completed. In this embodiment, when updating the inert gas supply amount command value, that is, when updating the command value determined in the command value determination step S4 as the latest inert gas supply amount command value, it is configured to gradually change over a predetermined time. Specifically, when it is after shifting to the transport mode with oxygen concentration control described above, update the inert gas supply amount command value at [F2] LPM / sec, and when shifting to the transport mode with oxygen concentration control, update the inert gas supply amount command value at [F1] LPM / sec. In this embodiment, [F2] is set to a value relatively smaller than [F1], and the change amount (LPM / sec) per second when updating the inert gas supply amount command value is set small. As a result, after shifting to the transport mode with oxygen concentration control, it will change relatively more gently than during the shift to the transport mode with oxygen concentration control. For example, when changing (updating) the inert gas supply amount command value from 200 LPM to 150 LPM after shifting to the transport mode with oxygen concentration control, that is, when decreasing the flow rate setting value to the purge MFC51a inside the housing by 50 LPM, gradually change the flow rate at 2 LPM per second for a total of 25 seconds so that the pressure inside the housing 2 does not fluctuate rapidly, and change the opening degree of the discharge valve of the discharge pipe 22d according to the inert gas supply amount.

[0068] As described above, according to the EFEM1 according to this embodiment, the supply amount of the inert gas into the housing 2 is set based on the oxygen concentration in the housing 2, and when the bottom purge process by the bottom purge device 36 is executed with the container door 43 open (when the determination result of the door open·bottom purge determination unit 12 is YES), the supply amount of the inert gas used for the bottom purge process (bottom purge inert gas supply amount) is subtracted from the total supply amount of the inert gas, and based on the subtracted value, an inert gas supply amount command value, which is a command value for the supply amount of the inert gas into the housing 2, is determined, and the supply amount of the inert gas into the housing 2 is controlled based on the inert gas supply amount command value. Thereby, taking into account the supply amount of the inert gas used during the execution of the bottom purge process, it is possible to control so as not to exceed the upper limit of the gas supply amount to the entire EFEM1 (the total supply amount of the inert gas set based on the oxygen concentration in the housing 2), avoid wasteful use of the inert gas such as discharging the inert gas from the housing 2 even though the oxygen concentration has not changed, and save the inert gas while always maintaining the pressure inside the housing 2 of the EFEM1 at a slightly positive pressure with a specified usage amount.

[0069] Particularly, in the EFEM1 according to this embodiment, during the execution of the inert gas supply control into the housing 2, when changing the supply amount of the inert gas into the housing 2 to the inert gas supply amount command value determined based on the calculation result of the in-housing inert gas supply amount calculation unit 13 (when updating the inert gas supply amount command value determined based on the calculation result of the in-housing inert gas supply amount calculation unit 13 as the latest inert gas supply amount command value), by controlling to gradually change it over a predetermined time, a rapid pressure change inside the housing 2 can be prevented and suppressed.

[0070] In addition, in the case where the EFEM1 according to the present embodiment includes a conveyance robot internal inert gas supply device (ejector R8, conveyance robot internal purge device R9) that supplies an inert gas into the conveyance robot R disposed in the substrate conveyance space 2Sa, or includes an ionizer 8 that performs static elimination of the substrate by locally supplying an inert gas to the substrate placed at a predetermined position in the substrate conveyance space 2Sa, since the inert gas supply amount command value is calculated and determined in consideration of these inert gas supply amounts, it is possible to control so as not to exceed 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), avoid wasteful use of the inert gas, and always maintain the pressure in the housing 2 of the EFEM1 at a slightly positive pressure with a specified usage amount.

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

[0072] As described above, the embodiments of the present invention have been described, but 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 appropriately changed and selected.

[0073] In the above embodiment, a FOUP is adopted as the substrate storage container. However, in the present invention, it is also possible to use storage containers other than the FOUP, for example, MAC (Multi Application Carrier), H-MAC (Horizontal-MAC), FOSB (Front Open Shipping Box), and the like.

[0074] In the above-described embodiment, nitrogen gas is taken as an example of the inert gas used for bottom purge processing and the like, but the present invention is not limited thereto, and a 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 illustrated, but a configuration in which less than three or four or more load ports are connected may also be adopted.

[0075] In addition, the specific configuration of each part is not limited to the above embodiment, and various modifications are possible without departing from the spirit of the present invention.

Explanation of Reference Numerals

[0076] 1…EFEM 11…Total Inert Gas Supply Amount Setting Unit 12…Door Open / Purge Judgment Unit (Door Open / Bottom Purge Judgment Unit) 13…Inert Gas Supply Amount Calculation Unit Inside the Housing 1C…Control Unit 2…Housing 3…Load Port 36…Bottom Purge Device 4…Substrate Storage Container (FOUP) 8…Ionizer R…Substrate Transfer Robot R8, R9…Inert Gas Supply Device Inside the Transfer Robot (Ejector, Purge Inside the Transfer Robot)

Claims

1. An EFEM comprising a housing having a substantially closed substrate transfer space therein, and a control unit configured to control at least the supply of an inert gas into the housing, wherein the control unit includes an inert gas supply total amount setting unit configured to set a total supply amount of the inert gas to be supplied into the housing based on the oxygen concentration in the housing; a door open / purge determination unit configured to determine, for each load port adjacent to the housing, whether or not purge processing is being performed by a purge device capable of replacing the gas atmosphere in a substrate storage container placed on a mounting table on which the substrate storage container can be placed with the container door of the substrate storage container in an open state; a housing internal inert gas supply amount calculation unit configured to calculate the supply amount of the inert gas into the housing based on a value obtained by subtracting the supply amount of the inert gas into the substrate storage container by the purge device of the load port from the total supply amount of the inert gas set by the inert gas supply total amount setting unit when the determination result of the door open / purge determination unit is YES; The EFEM is characterized in that the supply amount of the inert gas into the housing is controlled by an inert gas supply amount command value determined based on the calculation result of the housing internal inert gas supply amount calculation unit.

2. The EFEM according to claim 1, wherein when changing the supply amount of the inert gas into the housing to an inert gas supply amount command value determined based on the calculation result of the housing internal inert gas supply amount calculation unit, the change is controlled to be gradually made over a predetermined time.

3. The EFEM according to claim 1 or 2, further comprising an in-situ inert gas supply device configured to supply an inert gas into a substrate transfer robot disposed in the substrate transfer space, wherein when the in-situ inert gas supply device is in an inert gas supply state, the housing internal inert gas supply amount calculation unit is configured to calculate the supply amount of the inert gas into the housing based on a value obtained by subtracting at least the supply amount of the inert gas by the in-situ inert gas supply device from the total supply amount of the inert gas set by the inert gas supply total amount setting unit together with the supply amount of the inert gas into the substrate storage container.

4. The EFEM according to any one of claims 1 to 3, further comprising an ionizer configured to perform static elimination of a substrate by locally supplying an inert gas to the substrate placed at a predetermined location in the substrate transfer space. When the ionizer is in an inert gas supply state, the inert gas supply amount calculation unit in the housing 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 from the total inert gas supply amount set by the total inert gas supply setting unit together with the inert gas supply amount in the container. The EFEM according to any one of claims 1 to 3.

5. A method for controlling the inert gas supply amount into the housing in an EFEM including a housing having a substantially closed substrate transfer space therein and a control unit for controlling the supply of an inert gas into the housing, An inert gas supply total amount setting step of setting the total supply amount of the inert gas supplied into the housing based on the oxygen concentration in the housing; For each load port adjacent to the housing, a door open / purge determination step of determining whether or not the purge process by a purge device capable of replacing the gas atmosphere of the substrate storage container placed on a mounting table on which the substrate storage container of the load port can be mounted is in progress while the container door of the substrate storage container is in an open state; When the determination result of the door open / purge determination unit is YES, an inert gas supply amount calculation step for calculating the inert gas supply amount into the housing based on a value obtained by subtracting the inert gas supply amount in the container, which is the inert gas supply amount into the substrate storage container by the purge device of the load port, from the total supply amount of the inert gas set in the inert gas supply total amount setting step; A method for controlling the inert gas supply amount, characterized in that the inert gas supply amount into the housing is controlled based on the calculation result in the inert gas supply amount calculation step into the housing.

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