efem

Abstract

To provide an EFEM with a retreat station which can achieve reduction of a footprint and save a used amount of a purge gas.SOLUTION: An EFEM 1 includes: an EFEM body 2 in which a substrate transfer robot 22 is disposed in a substrate transfer space 21S formed in a housing 21; a retreat station 6 which is provided on a side wall 21 of the EFEM body 2 to communicate with the substrate transfer space 21S; and a purge gas supply chamber 5 provided at an upper part of the EFEM body 1. A return duct 7 which sends a purge gas flowing from the substrate transfer space 21S into the retreat station 6 to the purge gas supply chamber 5 is provided between the retreat station 6 and the purge gas supply chamber 5.SELECTED DRAWING: Figure 8

Description

[Technical Field]

[0001] The present invention relates to an Equipment Front End Module (EFEM) used for automatic substrate transport, which has a function of circulating a purge gas made of an inert gas such as nitrogen gas by connecting an evacuation station for temporarily evacuating substrates to 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, semiconductor manufacturing equipment has adopted a "mini-environment system" that further improves cleanliness only in the local space around the substrate, and is used for substrate transport and other processing. In the mini-environment system, a load port is installed adjacent to the front side of the EFEM housing, which has a nearly closed substrate transport space inside. A front-opening unified pod (FOUP), a container that stores substrates in a highly clean internal space, is placed on the load port, and the FOUP door can be opened and closed by the load port while in close contact with the FOUP door.

[0003] During semiconductor processing, various processes are performed on substrates. However, if the process gases, fumes (dust, chemical particles, etc.), and moisture used in each process are not removed, the substrates are exposed to environmental factors (high levels of humidity, high oxygen levels, and contaminating chemicals) within the semiconductor manufacturing equipment. This can lead to contamination within the semiconductor manufacturing equipment and adverse effects on the substrate characteristics, such as defects in the semiconductor devices fabricated on the substrates. Therefore, measures are taken to maintain a clean state by replacing the internal space of the EFEM housing and the FOUP with purge gas. Also, EFEMs with an evacuation station (sometimes called a "wafer station" when the substrate is a wafer) connected to the EFEM housing are becoming popular. The evacuation station temporarily evacuates substrates that have been transferred from the FOUP by a transfer robot located within the housing, and also temporarily evacuates substrates before they are transferred from the housing to the FOUP. In such an EFEM, the internal space of the housing and the internal space of the evacuation station are connected, and the internal spaces of both are replaced with purge gas to prevent and suppress deterioration of the substrate.

[0004] As an example of such an EFEM, Patent Document 1 discloses a configuration in which an evacuation station (referred to as a "side storage pod device" in the document) capable of accommodating wafers stacked in multiple stages is provided on one side of the EFEM housing. This EFEM employs a configuration in which the evacuation station includes a side storage container connected to the EFEM housing (EFEM chamber) through an opening to allow purge gas to flow in from the EFEM housing; a side storage chamber configured to support substrates within the side storage container; a plenum chamber provided to communicate with the inner end of the side storage chamber (the side when the EFEM is viewed from the front); a holding container surrounding the side storage chamber and the plenum chamber; and an exhaust port for exhausting purge gas from the lower end of the plenum chamber. A baffle plate (baffle plate) is disposed between the side storage chamber and the plenum chamber. The baffle plate has numerous circular perforations whose opening areas gradually decrease from top to bottom to rectify the purge gas flow and maintain uniformity.

[0005] Although not an example of EFEM, Patent Document 2 discloses an example of a FOUP configuration that takes into consideration the uniformity of such purge gas flow, in which spaces are formed between the side walls and front walls of a multi-stage slot that holds wafers and the side walls and front walls of the FOUP housing, and circular perforations or oblong slits are formed in the side walls and front walls of the multi-stage slot, with the opening areas of these perforations or slits gradually decreasing from the top to the bottom. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] International Publication No. 2020 / 086706 (Patent No. 7137697) [Patent Document 2] Korean Patent No. 10-1684431 Summary of the Invention [Problem to be solved by the invention]

[0007] In the conventional EFEM described above, the purge gas supplied to the evacuation station is discharged to the outside from an exhaust port provided at the lower end of the evacuation station, as disclosed in Patent Document 1. However, the discharged purge gas is returned to the EFEM via a circulation path provided outside the evacuation station. This configuration leads to an increase in the size of the entire device, which does not meet the trend of minimizing the footprint of the device.

[0008] The present invention focuses on these points and aims to provide an EFEM equipped with an evacuation station that has a configuration suitable for removing process gases, fumes, and moisture according to the substrate loading position within the evacuation station, and that also contributes to a smaller footprint for the entire equipment. [Means for solving the problem]

[0009] That is, the present invention is an EFEM comprising an EFEM main body in which a substrate transport robot is placed in a substrate transport space formed inside a housing, an evacuation station which is provided on the side wall of the EFEM main body so as to communicate with the substrate transport space and which can be accessed by the substrate transport robot to temporarily store substrates, and a purge gas supply chamber which is provided on the top of the EFEM main body and supplies clean purge gas to the substrate transport space, and is characterized by a configuration in which a return duct is provided between the evacuation station and the purge gas supply chamber which is located above it, for sending purge gas which has flowed into the evacuation station from the substrate transport space to the purge gas supply chamber.

[0010] In an EFEM with such a configuration, the evacuation station may be provided in communication with one of the two side walls of the housing of the EFEM main body, or may be provided in communication with both side walls. Furthermore, an inert gas such as purified and dried nitrogen gas is used as the purge gas. The purge gas supply chamber is a space provided in the upper part (ceiling) of the EFEM main body, and an FFU (Fan Filter Unit) is provided at the boundary with the substrate transfer space. The FFU incorporates, as a unit, a fan that blows purge gas toward the substrate transfer space and a filter that purifies the purge gas before it is sent from the fan into the substrate transfer space.

[0011] In this EFEM, the purge gas supplied from the purge gas supply chamber is sent from the substrate transfer space of the EFEM to the evacuation station, where it forms an updraft from above the evacuation station and is returned to the purge gas supply chamber via the return duct. Compared to conventional configurations in which purge gas discharged below the evacuation station circulates around the outside of the evacuation station and is returned to the EFEM, this configuration reduces the overall size of the EFEM and contributes to a smaller footprint for the EFEM. The smaller footprint of the EFEM also contributes to an increase in the number of EFEMs installed per given floor area and improved production efficiency throughout the substrate manufacturing plant. Furthermore, the purge gas sent from the evacuation station is returned to the purge gas supply chamber via the return duct and supplied to the substrate transfer space in a purified state, creating a purge gas circulation path that reduces the amount of purge gas used.

[0012] Considering the simplification of the return duct piping configuration and installation work, the reduction of the footprint of the entire EFEM, and the fact that the purge gas is returned to the purge gas supply chamber as an ascending air current through the return duct, it is desirable that the connection point of the return duct at the evacuation station be located above the bottom of the evacuation station. In particular, by configuring the return duct to connect the top of the evacuation station to the purge gas supply chamber, the footprint of the entire EFEM can be further reduced.

[0013] Furthermore, the evacuation station can be configured to include a baffle plate with numerous holes formed at the rear of the substrate storage shelf (the "rear" is the "rear" when the entrance / exit side communicating with the substrate transfer space is defined as the "front," and corresponds to the side when viewed from the perspective of the entire EFEM), and a sealing plate that is provided along the back surface of the baffle plate and can move up and down according to the loading position of the substrates on the substrate storage shelf, so that purge gas can be sent to the return duct through the holes in the baffle plate in an area that does not overlap with the sealing plate. With this configuration, not only can the baffle plate rectify the purge gas flow within the evacuation station, but the sealing plate can also adjust the purge gas flow according to the loading position of the substrates within the evacuation station. Therefore, compared to conventional methods of exhausting purge gas in evacuation stations, it is possible to achieve effects such as lowering the substrate temperature, removing fumes, and shortening the time required for drying, thereby improving substrate production efficiency.

[0014] Furthermore, by forming the holes in the baffle plate so that the opening area gradually increases from the upper end side to the lower end side, the amount of purge gas flowing out through the holes in the baffle plate can be increased the farther from the return duct, thereby more appropriately improving the uniformity of the purge gas flow sent upward from the evacuation station to the return duct.

[0015] Furthermore, the return duct is provided with a fan inside that raises the flow of purge gas, and the rotation speed of the fan is configured to be changeable according to the up and down movement of the sealing plate, thereby promoting the upward flow of the purge gas within the return duct while appropriately adjusting the flow rate of the purge gas returned via the return duct according to the loading position of the substrate within the evacuation station. [Effects of the Invention]

[0016] The EFEM equipped with the evacuation station of the present invention has a return duct connecting the evacuation station to the purge gas supply chamber provided at the top of the EFEM body, and the purge gas sent to the evacuation station is returned to the purge gas supply chamber through this return duct. This allows a purge gas circulation path to be formed without increasing the footprint of the EFEM. This not only saves on purge gas consumption, but also allows more EFEMs to be installed in a substrate manufacturing factory with limited space, contributing to improved substrate production efficiency. [Brief explanation of the drawings]

[0017] [Figure 1] FIG. 1 is a schematic front view showing the appearance of an EFEM according to an embodiment of the present invention. [Figure 2] FIG. 2 is a schematic plan view showing the appearance of the EFEM. [Figure 3] FIG. 2 is a schematic perspective view showing the evacuation station and return duct in the EFEM. [Figure 4] A schematic longitudinal cross-sectional view of the evacuation station and return duct in the EFEM. [Figure 5] FIG. 2 is an enlarged perspective view showing a retraction station in the EFEM. [Figure 6] 3A and 3B are perspective views showing a baffle plate and a sealing plate in the EFEM. [Figure 7] FIG. 10 is a perspective view illustrating a state in which the sealing plate is moved up and down by the lifting mechanism in the EFEM. [Figure 8] FIG. 2 is an explanatory diagram showing the flow of purge gas in the EFEM. DETAILED DESCRIPTION OF THE INVENTION

[0018] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0019] As shown in FIGS. 1 and 2 , an EFEM (Equipment Front End Module) 1 according to this embodiment includes a housing 21 of an EFEM main body 2 and a load port 3, which are placed on the floor F of a semiconductor manufacturing factory, which is a clean room. A front-opening unified pod (FOUP) 8 shown in the figures is a type of substrate storage container. In this embodiment, wafers (not shown), which are semiconductor substrates, are stored on multi-tiered shelves. The wafers are transported between the outside of the EFEM 1 and the load port 3. When a wafer is placed on the load port 3, a rear door is opened and closed by the load port 3. When the door is open, an arm robot (substrate transport robot) 22 installed in a substrate transport space 21S within the housing 21 transports the wafer. A semiconductor processing device 9 is provided adjacent to the rear wall 21b of the housing 21 of the EFEM main body 2, opposite the front wall 21a on which the load port 3 is located, via a load lock 4. The arm robot 22 may be of either a traveling type that moves on rails laid inside the housing 21 or a stationary type in which the robot itself does not move.

[0020] The upper part of the housing 21 of the EFEM main body 2, i.e., the space above the substrate transfer space 21S, is set up as a purge gas supply chamber 5. The purge gas supply chamber 5 is provided with an FFU (Fan Filter Unit, not shown) 51. Operating the FFU 51 generates a downward air current in the substrate transfer space 21S, and blows highly clean inert gases such as nitrogen gas or CDA (highly clean dry air) into the substrate transfer space 21S as purge gas, thereby maintaining high cleanliness within the substrate transfer space 21S and the FOUP 8 installed on the load port 3. Here, we will assume that nitrogen gas is used as the purge gas. Nitrogen gas is supplied to the purge gas supply chamber 5 from a nitrogen gas source installed in the EFEM 1 or semiconductor manufacturing plant. The FFU 51 basically sends the nitrogen gas from the purge gas supply chamber 5, supplied from the nitrogen gas source, to the substrate transfer space 21S below using a fan, while purifying the nitrogen gas before sending it out using a filter. When the FFU 51 is driven, nitrogen gas that has passed through the filter and been purified is sent from the purge gas supply chamber 5 to the substrate transfer space 21S, where it flows downward, forming a laminar flow (downflow). In this embodiment, a filter (such as a chemical filter) that removes fumes, contaminants, moisture, etc. is placed at the bottom of the purge gas supply chamber 5. In addition, the bottom of the housing 21 of the EFEM main body 2 is provided with multiple exhaust ports M with exhaust valves that exhaust nitrogen gas from the substrate transfer space 21S, and exhaust pipes N that connect each exhaust port M to the outside, so that excess nitrogen gas after use can be discharged to the outside (see FIG. 8).

[0021] As shown in FIGS. 1 and 2 , a retreat station 6 is connected to each of both side walls 21c of the housing 21 of the EFEM main body 2. The retreat station 6 is provided to temporarily store wafers and remove process gases, fumes, and moisture adhering to the wafers. The retreat station 6 temporarily stores wafers transferred from the FOUP 8 to the substrate transfer space 21S, and then transports them to the semiconductor manufacturing equipment 9 via the substrate transfer space 21S and the load lock 4. Conversely, the retreat station 6 temporarily stores wafers transferred from the semiconductor processing equipment 9 to the substrate transfer space 21S via the load lock 4, and then transports them to the FOUP 8. Wafers are transported between the FOUP 8, the substrate transfer space 21S, the retreat station 6, and the load lock 4 by an arm robot 22. When the substrates stored in the retreat station 6 are wafers, the retreat station 6 is sometimes referred to as a wafer station.

[0022] As shown in Figures 3, 4, and 5, the evacuation station 6 is a rectangular box-shaped main body 61 with an open front 61a. Inside the main body 61 is a substrate storage shelf 62 (hereinafter simply referred to as "shelf 62") capable of stacking wafers in multiple layers. The open front of the main body 61 is aligned with openings (not shown) formed in the middle of the height direction of both side walls 21c of the housing 21 of the EFEM main body 2. This allows wafers to be temporarily stored in the evacuation station 6, and clean nitrogen gas supplied from the purge gas supply chamber 5 through the substrate transfer space 21S can be introduced to remove process gas, fumes, and moisture adhering to the wafers. The nitrogen gas flowing into the evacuation station 6 is sent out to the return duct 7 through a delivery port 61c formed in the upper end 61b of the main body 61. The upper end of the return duct 7 is connected to the purge gas supply chamber 5 from the side, and the gas is purified by the FFU before being sent back to the substrate transfer space 21S.

[0023] The evacuation station 6 is provided with a baffle plate 63 and a sealing plate 64 used to rectify the flow of nitrogen gas within the main body 61, located adjacent to the rear of the shelf 62. As shown in Figures 3, 4, 5, and 6(a), the baffle plate 63 is a plate-like member made of metal such as stainless steel or aluminum that is curved to correspond to the shape of the rear end of the shelf 62, and has a large number of holes 63a formed therethrough to allow nitrogen gas to pass through. The holes 63a are formed by forming a plurality of circular holes in the width direction and in multiple stages in the height direction, with the diameter (opening area) gradually varying so that the diameter (opening area) is smaller toward the upper stages and larger toward the lower stages, and the holes 63a at the same height have the same diameter.

[0024] As shown in FIGS. 4, 5, and 6(b), the sealing plate 64 is a plate-shaped member made of a metal such as stainless steel or aluminum, curved to correspond to the curved shape of the rear side of the baffle plate 63. The sealing plate 64 is disposed adjacent to the rear side of the baffle plate 63 with a very small gap (e.g., about 0.1 to 1 mm) between it and the baffle plate 63. The height and width of the sealing plate 64 along the curved direction are substantially the same as those of the baffle plate 63. The space between the sealing plate 64 and the rear wall 61d of the main body 61 at the rear of the main body 61 serves as an air supply space 65 communicating with the return duct 7. As shown in FIG. 7, the sealing plate 64 can be moved up and down by a lifting mechanism 66 disposed within the return duct 7 in accordance with the loading position of the wafers loaded on the shelf 62. The lifting mechanism 66 may be an appropriate mechanism such as a stepping motor or an air cylinder. The sealing plate 64 blocks the holes 63a of the baffle plate 63 in the area where it overlaps, so that the nitrogen gas flow is hardly allowed to flow from the shelf 62 side of the main body 61 to the air supply space 65 side through the holes 63a blocked by the sealing plate 64. In this embodiment, it is assumed that wafers are loaded on the shelf 62 in order from the bottom up. When wafers are loaded only on the bottom, the lifting mechanism 66 lowers the sealing plate 64 to open the holes 63 a on the bottom side of the baffle plate 63. When wafers are loaded from the bottom up to the middle, the lifting mechanism 66 raises the sealing plate 64 from the lowered position to the intermediate height position to open the holes 63 a on the bottom to the middle of the baffle plate 63. When wafers are loaded from the bottom up to the top, the lifting mechanism 66 raises the sealing plate 64 to the upper end side to open almost all of the holes 63 a on the bottom to the top of the baffle plate 63. This allows the purge gas in the main body 61 to be sent from the air supply space 65 to the return duct 7 through the opened holes 63 a. The loading position of the wafers on the shelf 62 can be determined by signals or information detected by an appropriate sensor such as a stock sensor, and the control unit of the EFEM 1 can be configured to control the up and down movement of the sealing plate 64 by the lifting mechanism 66 based on this information.Furthermore, when no wafers are loaded on the shelf 62, it is desirable to raise the sealing plate 64 to the top to form a circulation path in which nitrogen gas is sent from the main body 61 to the return duct 7 and returned to the purge gas supply chamber 5, so that no air remains in the return duct 7 and the oxygen concentration in the housing 21 does not increase. However, after the entire internal environment from the purge gas supply chamber 5 to the substrate transfer space 21s in the housing 21, the evacuation station 6, and the return duct 7 has been sufficiently replaced with nitrogen gas, the sealing plate 64 can be controlled to be raised and lowered as appropriate depending on the degree of contamination and oxygen concentration in the substrate transfer space 21s. For example, if the sealing plate 64 is lowered to the bottom, the oxygen concentration in the housing 21 and the evacuation station 6 can be quickly reduced.

[0025] 1, 2, 3, and 4, the return duct 7 is a rectangular tubular member that is erected with its lower end 7a connected to a delivery port (not shown) formed in the upper end 61b (directly above the gas supply space 65) of the main body 61 of the evacuation station 6, and its upper end 7b is bent horizontally to connect to an opening (not shown) formed in the side wall 52 of the purge gas supply chamber 5. Fans 71 are disposed at appropriate locations (two locations at different heights in this embodiment) within the return duct 7 (see FIG. 8) to efficiently promote an upward current of the nitrogen gas flow from the gas supply space 65 of the evacuation station 6 to the purge gas supply chamber 5 located above it. The fans 71 also play a role in controlling the internal pressure of the substrate transfer space 21S and the interior of the evacuation station 6 that are connected thereto, as well as the purge gas supply chamber 5, and the return flow of the purge gas. Here, by configuring the rotation speed of the fan 71, which affects the air volume or velocity of the nitrogen gas flow, to be changed depending on the height position of the sealing plate 64 set by the lifting mechanism 66, it is possible to adjust the appropriate return flow rate to the purge gas supply chamber 5 depending on the flow rate of nitrogen gas delivered from the evacuation station 6. For example, it is possible to determine the rotation speed of the fan 71 in advance depending on the elevation of the sealing plate 64, which is directly related to the degree to which the holes 63a in the baffle plate 63 are opened. In this case, a reference rotation speed is determined such that the rotation speed of the fan 71 is set higher when the sealing plate 64 is at its lowest position because the flow of purge gas flowing into the return duct 7 is small, and the rotation speed of the fan 71 is set lower when the sealing plate 64 is at its highest position because the flow of purge gas flowing into the return duct 7 is large. A control method is conceivable in which the rotation speed of the fan 71 is set to be lower when the sealing plate 64 is at its lowest position so that the flow of purge gas flowing into the return duct 7 is large, and the rotation speed of the fan 71 is feedback-controlled depending on the value detected by a pressure gauge to suppress changes in the internal pressure of the purge gas supply chamber 5, etc.

[0026] Here, the flow of nitrogen gas when the EFEM 1 is in operation will be described with reference to Figure 8. When the EFEM 1 is started, the FFU 51 in the purge gas supply chamber 5 also starts, and a purified nitrogen gas flow G1 is supplied as a downflow into the housing 21 of the EFEM main body 2. The downflow nitrogen gas flow G1 is also supplied into the main body 61 of the evacuation station 6. In this state, the gas environment inside the housing 21 of the EFEM main body 2 and the main body 61 of the evacuation station 6 is purged with nitrogen gas, and becomes a clean state in which fumes, contaminants, moisture, etc. have been removed. At this time, if the sealing plate 64 in the evacuation station 6 is positioned above the lowest level, the nitrogen gas flow G3 also flows into the air supply space 65 through the hole 63a in the baffle plate 63, and the nitrogen gas flow G4 that has become an ascending air current is returned to the purge gas supply chamber 5 through the return duct 7, thereby forming a circulation path for the nitrogen gas flow.The nitrogen gas returned to the purge gas supply chamber 5 is purified by the FFU 51 together with the nitrogen gas supplied from the nitrogen gas source, and is supplied again into the housing 21 as a downflow nitrogen gas flow G1.

[0027] When the door of a FOUP 8 placed on the load port 3 is opened, a downflowing nitrogen gas flow G1 fills the interior of the FOUP 8, purging it and removing fumes, contaminants, moisture, and the like adhering to the interior of the FOUP 8 and the wafers loaded in the FOUP 8. When the arm robot 22 removes wafers from the FOUP 8, transports them to the evacuation station 6, and loads the wafers on the shelf 62, the elevating mechanism 66 moves the sealing plate 64 up and down according to the loading position, allowing nitrogen gas to pass through the wafer loading position and clean the wafers. Then, the nitrogen gas flow G3, which has cleaned the wafers and flowed from the shelf 62 side into the air supply space 65 through the open holes 63a of the baffle plate 63 in the area not overlapping with the sealing plate 64, flows into the air supply space 65 from the shelf 62 side through the return duct 7 as an ascending air current and is returned to the purge gas supply chamber 5. In addition to the downflow purge gas flow G1, the FOUP 8 can be purged with nitrogen gas by direct purging using a purge nozzle provided at the bottom of the FOUP 8 or by front purging, which sprays nitrogen gas toward the opening that opens when the door of the FOUP 8 is opened.

[0028] Wafers processed in semiconductor manufacturing equipment 9 and removed from the load lock 4 by the arm robot 22 are loaded back into the evacuation station 6 and loaded onto the shelf 62. Because wafers are contaminated with process gases and fumes, they are transported back to the evacuation station 6 and loaded onto the shelf 62. Nitrogen gas passes through the wafer loading position by moving the sealing plate 64 up and down using the lifting mechanism 66 according to the wafer's loading position on the shelf 62, cleaning the wafer and removing process gases and fumes. The nitrogen gas flow G3, which flows from the shelf 62 to the air supply space 65 through the open holes 63a in the baffle plate 63 in the area not overlapping with the sealing plate 64, cleans the wafer and returns to the purge gas supply chamber 5 as an ascending air current through the return duct 7. The restored wafers are then removed from the evacuation station 6 by the arm robot 22 and transported through the housing 21 of the EFEM main body 2 to the FOUP 8 on the load port 3. The FOUP 8 continues to be purged with the downflowing nitrogen gas flow G1.

[0029] The downflow nitrogen gas flow G1 supplied to the housing 21 of the EFEM main body 2 and a portion of the nitrogen gas flow G2 flowing at the bottom of the housing 21 are discharged to the outside of the EFEM main body 1 through the exhaust port M and exhaust pipe N by opening and closing the exhaust valve at the bottom of the housing 21 as needed, when the exhaust valve is in the open state.

[0030] As described above, the EFEM 1 of this embodiment has a purge gas supply chamber 5 above the EFEM main body 1, and an evacuation station 6 adjacent to and connected to both side walls 21c of the EFEM main body 1. The return duct 7 connects the top of the evacuation station 6 to the purge gas supply chamber 5, eliminating the need to install a path for exhausting purge gas (nitrogen gas) from the evacuation station 6 beyond the footprint of the EFEM 1. This reduces the footprint, allowing more EFEMs to be installed in the limited space required for semiconductor manufacturing, and improving wafer production efficiency. Furthermore, instead of exhausting nitrogen gas to the outside, the nitrogen gas that passes through the evacuation station 6 is returned to the purge gas supply chamber 5 through the return duct 7, purified by the FFU 51, and resupplied into the housing 21 of the EFEM main body 2. This circulation path also reduces the amount of nitrogen gas used.

[0031] In particular, a baffle plate 63 and a sealing plate 64 are arranged in a stacked manner along the rear of a shelf 62 of the evacuation station 6, and the sealing plate 64 is configured to be moved up and down by a lifting mechanism 66 according to the wafer loading position on the shelf 62. Therefore, depending on the height position of the sealing plate 64, nitrogen gas does not flow into the rear air supply space 65 from the holes 63a of the baffle plate 63 in the area overlapping with the sealing plate 64, and nitrogen gas after cleaning the wafers flows from the shelf 62 side to the air supply space 65 only from the holes 63a of the baffle plate 63 in the area not overlapping with the sealing plate 64 and is sent to the return duct 7. As in the prior art, methods are being developed to remove process gases, fumes, and moisture that contaminate loaded substrates in temporary substrate storage devices such as evacuation stations. However, during actual operation of an EFEM, substrates are not necessarily loaded and stored in the entire storage space, and there are cases where substrates are loaded only in a portion of it. In such a case, if a baffle plate or wall having perforations or slits as described above is used, a large amount of purge gas will be sent to areas where no substrates are loaded, resulting in waste. In contrast, in this embodiment, not only is the nitrogen gas flow rectified by the baffle plate 63, but the nitrogen gas flow can also be adjusted by the sealing plate 64 according to the wafer loading position on the shelf 62, making it possible to appropriately reduce the substrate temperature, remove fumes and process gases, and shorten the drying time by removing moisture, thereby improving wafer production efficiency.

[0032] Furthermore, the opening area of the holes 63a in the baffle plate 63 is set smaller in the upper stages closer to the return duct 7 and larger in the lower stages farther from the return duct 7, thereby further improving the uniformity of the nitrogen gas flow within the evacuation station 6.

[0033] Furthermore, a fan 71 is provided inside the return duct 7 to promote the upward movement of the nitrogen gas flow sent from the evacuation station 6, and the rotation speed of this fan 71 can be changed according to the up and down movement of the sealing plate 64, so that the flow rate of the nitrogen gas sent to the purge gas supply chamber 5 via the return duct 7 can be appropriately adjusted according to the loading position of the wafers on the shelf 62.

[0034] The present invention is not limited to the above-described embodiment. For example, in this embodiment, the baffle plate 63 and sealing plate 64 in the evacuation station 6 have a curved shape corresponding to the shape of the rear end of the shelf 62 on which disk-shaped wafers are loaded, but they can also be flat regardless of the shape of the shelf 62. If the substrates handled by the EFEM are rectangular, the rear end of the shelf will be linear, so the baffle plate and sealing plate can also be flat.

[0035] Furthermore, the return duct 7 does not have to be rectangular, but may be cylindrical, and when a fan 71 is placed inside, the number of fans 71 is not limited to two, but can be one or three or more, depending on the length and volume of the return duct 7.

[0036] Furthermore, in the above-described embodiment, a configuration in which the return duct 7 is connected to the top (upper end) of the evacuation station 6 has been described, but as long as this does not hinder the reduction in footprint of the EFEM1, a configuration in which the return duct 7 is connected to the back wall 61d or side wall of the evacuation station 6 may also be adopted, and further, a return duct that is not directly connected to the evacuation station 6 but connects the housing 21 and the purge gas supply chamber 5 may also be applied.

[0037] Furthermore, the specific configuration of each part of the EFEM is not limited to the above embodiment, and various modifications are possible within the scope of the present invention. [Explanation of symbols]

[0038] 1...EFEM 2...EFEM main body 21...Case 21S: Substrate transport space 22...Substrate transport robot (arm robot) 5...Purge gas supply chamber 6...Evacuation station 62... Substrate storage shelf (shelf) 63...Baffle plate 63a…hole 64...Sealing plate 7...Return duct 71...Fan

Claims

1. An EFEM comprising: an EFEM main body in which a substrate transfer robot is disposed in a substrate transfer space formed inside a housing; an evacuation station provided on a side wall of the EFEM main body so as to communicate with the substrate transfer space and accessible by the substrate transfer robot to temporarily store a substrate; and a purge gas supply chamber provided on an upper portion of the EFEM main body for supplying a clean purge gas to the substrate transfer space, An EFEM characterized in that a return duct is provided between the evacuation station and the purge gas supply chamber located above the evacuation station, for sending the purge gas that has flowed into the evacuation station from the substrate transfer space to the gas supply chamber.

2. 2. The EFEM according to claim 1, wherein the return duct is provided between an upper portion of the evacuation station and the purge gas supply chamber.

3. 3. The EFEM of claim 1, wherein the evacuation station is provided with a baffle plate having a large number of holes formed at the rear of a substrate storage shelf provided within the evacuation station, and a sealing plate provided along the back surface of the baffle plate and capable of moving up and down to match the loading position of the substrate on the substrate storage shelf, and the purge gas is sent to a return duct through the holes in the baffle plate in an area that does not overlap with the sealing plate.

4. 4. The EFEM according to claim 3, wherein the plurality of holes in the baffle plate are formed so that the opening area gradually increases from the upper end side toward the lower end side.

5. 4. The EFEM according to claim 3, wherein a fan for raising the airflow of the purge gas is provided inside the return duct, and the rotation speed of the fan is changeable in accordance with the up and down movement of the sealing plate.

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