Wafer memory

Abstract

A wafer storage device is provided that can further improve the atmosphere around the wafer. The wafer storage device (X) includes: a housing (1), a loading device (2) provided on the front surface of the housing (1), a wafer cassette rack (3) provided in the housing (1), a wafer transfer robot (4) for transferring wafers into a wafer cassette (C) on the wafer cassette rack (3) from a transfer container mounted on the loading device (2) and for transferring wafers out of the wafer cassette (C), a wafer cassette transfer device (5) for moving the wafer cassette (C) on the wafer cassette rack (3) to different heights, and a fan filter unit (8) for generating a laminar flow in the wafer transfer space and the wafer cassette transfer space.

Description

Technical Field

[0001] The present invention relates to a wafer storage for temporarily storing wafers. Background Art

[0002] In the process of manufacturing semiconductor devices, in order to improve production yield and quality, wafers are processed in a clean room. To appropriately maintain the atmosphere around the wafers, a storage pod (transport container) called a FOUP (Front-Opening Unified Pod) is used. In the related art, a FOUP storage for temporarily storing such a FOUP in a clean room is known (for example, see Patent Document 1).

[0003] The FOUP storage includes a plurality of shelves arranged in multiple layers in the height direction, and is configured such that a FOUP containing wafers before processing and a FOUP containing wafers after processing can be placed on the shelves. In other words, the FOUP storage is configured to place and store the entire FOUP (the entire FOUP containing wafers) on the shelves in the FOUP storage.

[0004] Prior Art Documents

[0005] Patent Documents

[0006] Patent Document 1: Japanese National-Phase Publication of International Patent Application No. 2009-541599

[0007] With the further miniaturization of semiconductor devices, it may be necessary to further improve the atmosphere around the wafers even in the internal space of the storage. Since there is a small amount of dust even in the clean room, the dust may adhere to the surface of the FOUP. In addition, since the FOUP is usually made of a water-absorbing resin material, moisture in the atmosphere in the clean room may be introduced into the FOUP. If such a FOUP is introduced into the FOUP storage described in Patent Document 1, it may be difficult to maintain a good atmosphere in the FOUP storage due to the dust or moisture released from the FOUP. Therefore, in the configuration of storing the entire FOUP in the storage as described in Patent Document 1, even if the storage is filled with nitrogen or dry air, for example, it may hinder the improvement of the atmosphere around the wafers.

[0008] Embodiments of the present invention provide a wafer storage capable of improving the atmosphere around the wafers. Summary of the Invention

[0009] According to an embodiment of the present invention, a wafer storage includes: a housing; a loading device mounted on a front surface of the housing and configured to mount a transfer container capable of accommodating a plurality of wafers; a cassette rack disposed in the housing and configured to store a plurality of cassettes in a multi-layer manner, the cassettes being configured to store a plurality of wafers in a multi-layer manner; a wafer transfer robot configured to load and unload wafers between the transfer container mounted on the loading device and the cassettes stored in the cassette rack; a cassette transfer device configured to move a cassette stored in a predetermined layer among the multi-layers of the cassette rack to a layer at least different in height from the predetermined layer; and a fan filter unit configured to generate a laminar flow in a wafer transfer space of the housing where the wafer transfer robot is disposed and in a cassette transfer space of the housing where the cassette transfer device is disposed.

[0010] The wafer storage according to the present invention has a structure in which wafers are stored in units of cassettes capable of accommodating wafers in multiple layers. Therefore, compared with a storage that accommodates an entire transfer container such as a FOUP in the related art, it is possible to prevent or suppress the situation where dust attached to the outer surface of the transfer container enters the housing and diffuses or accumulates in the housing.

[0011] In addition, the wafer storage according to the present invention has a structure in which wafers are generally stored by using cassettes smaller than the transfer container. Therefore, compared with a storage that accommodates a transfer container in the related art, the size of the entire storage can be reduced, the number of wafers to be stored can be increased, and the occupied area can be reduced. Furthermore, since the wafer storage according to the present invention has a structure in which cassettes are transported in the housing, when wafers are moved to different layers, the transfer efficiency can be improved compared with the case of moving wafers one by one.

[0012] Furthermore, in the wafer storage according to the present invention, a laminar flow is generated in the wafer transfer space and the cassette transfer space by the fan filter unit. Therefore, the diffusion of dust generated during the operation of the wafer transfer robot or the operation of the cassette transfer device can be suppressed.

[0013] In addition, in the wafer storage according to the present invention, the wafer transfer robot can be configured to transport wafers between the transfer container mounted on the loading device and the cassette disposed in a layer in the multi-layers of the cassette rack and having a height facing the transfer container in the front-rear direction.

[0014] In this way, the time required to transport wafers between the transfer container and the cassette can be minimized, and the time spent can be shortened.

[0015] In addition, in the wafer storage according to the present invention, a circulation path for circulating gas can be formed in the housing, and the circulation path includes the wafer transfer space and the cassette transfer space.

[0016] Thus, for example, compared with a configuration in which gas is supplied into a casing and all of it is discharged from the casing, the amount of gas to be supplied can be reduced and the running cost can be lowered.

[0017] According to the present invention, a wafer storage capable of improving the atmosphere around a wafer can be provided. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 is an overall schematic view of a wafer storage according to an embodiment of the present invention.

[0019] Figure 2 is Figure 1 an exploded view of the wafer storage shown.

[0020] Figure 3 is Figure 1 an enlarged view of a part of

[0021] Figure 4 is a schematic side view showing an operation flow of a loading device according to an embodiment.

[0022] Figure 5 is a schematic side view of a wafer storage showing a gas circulation path according to an embodiment.

[0023] Figure 6 is showing according to Figure 1 a view of an operation flow of a wafer storage according to an embodiment corresponding to

[0024] Figure 7 is showing according to Figure 1 a view of an operation flow of a wafer storage according to an embodiment corresponding to

[0025] Figure 8 is showing according to Figure 1 a view of an operation flow of a wafer storage according to an embodiment corresponding to

[0026] Figure 9 is showing according to Figure 1 a view of an operation flow of a wafer storage according to an embodiment corresponding to

[0027] Figure 10 is an exploded view of a wafer storage according to a modification.

[0028] Figure 11 is an exploded view of a wafer storage according to another modification. DETAILED DESCRIPTION OF THE INVENTION

[0029] Embodiments of the present invention will now be described in detail with reference to the drawings.

[0030] The wafer storage X according to the present embodiment (see Figure 1 ) is provided in a clean room for a semiconductor manufacturing process. The wafer storage X can temporarily store wafers taken out from a transfer container capable of accommodating wafers inside a housing 1 that maintains a high level of cleanliness.

[0031] In the present embodiment, a FOUP 10 is used as the transfer container. As shown in Figure 4 (a) to (d), the FOUP 10 includes a FOUP main body Y3 (transfer container main body) and a FOUP door Y2 (transfer container door). The FOUP main body Y3 has an internal space YS that can be opened through a loading / unloading port Y1 serving as an opening, and the FOUP door Y2 can open and close the loading / unloading port Y1. The FOUP 10 is configured to accommodate a plurality of wafers in a multi-layer shape in the height direction H so that these wafers can be loaded and unloaded through the loading / unloading port Y1. As will be described later, Figure 4 (a) to (d) are schematic diagrams showing the operation process of the FOUP10, and this operation process follows Figure 4 (a), (b), (c), and (d) in sequence.

[0032] The FOUP main body Y3 includes a shelf portion (wafer mounting shelf) capable of mounting multiple layers of wafers at a predetermined interval in the internal space YS. As shown in Figure 4 (a), a port Y4 is mounted at a predetermined position on the bottom wall of the FOUP main body Y3. The port Y4 has, for example, a hollow cylindrical gasket seal fitted in a port mounting through hole formed in the bottom wall of the FOUP main body Y3 and is configured to be opened and closed by a check valve. A flange portion clamped by a container transfer device such as an OHT is mounted at the central portion of the upper surface of the upper wall of the FOUP main body Y3.

[0033] The FOUP door Y2 is a substantially plate-shaped member. The FOUP door Y2 is arranged to face the loading device door 23 of the loading device 2 in a state of being mounted on the mounting table 21 (described later) of the loading device 2. The FOUP door Y2 is provided with a latch wedge (not shown) for locking the FOUP door Y2 to the FOUP main body Y3. A gasket Y5 is provided in a predetermined portion of the FOUP door Y2, and this predetermined portion contacts or approaches the FOUP main body Y3 in a state where the loading / unloading port Y1 is closed by the FOUP door Y2. The FOUP door Y2 is configured such that the internal space YS of the FOUP 10 can be sealed by bringing the gasket Y5 into contact with the FOUP main body Y3 and elastically deforming the gasket Y5 (see Figure 4 (a) and (c)).

[0034] In the storage in which the entire FOUP 10 is stored as disclosed in the related art, even if the atmosphere in the space for storing the FOUP 10 is filled with nitrogen, dry air, etc. to achieve a high cleanliness, dust, etc. attached to the surface of the FOUP 10 in the clean room may be brought into the storage and accumulate therein. In addition, generally, the FOUP 10 is formed of a water-absorbing resin material (e.g., polycarbonate). Therefore, even if the internal space of the storage disclosed in the related art is filled with nitrogen, dry air, etc., the moisture of the FOUP 10 introduced into the clean room will diffuse in the storage. This makes it difficult to control and maintain a low humidity in the internal space of the storage. As described above, in the configuration in which the entire FOUP is stored in the storage, it may be difficult to further improve the atmosphere around the wafer. Therefore, in order to further improve the atmosphere around the wafer, the wafer storage X of the present embodiment is specifically configured as follows.

[0035] As Figure 1 and Figure 2 shown, the wafer storage X according to the present embodiment includes a housing 1, a loading device 2, a wafer cassette rack 3, a wafer transfer robot 4, and a wafer cassette transfer device 5. The loading device 2 is arranged in close contact with the front wall 11 of the housing 1, thereby forming a part of the front wall 11 of the housing 1. The loading device 2 includes a mounting table 21 on which a wafer can be mounted. The wafer cassette rack 3 is mounted at a position in the housing 1 that is spaced backward from the front wall 11 of the housing 1 by a predetermined distance, and is configured to store a plurality of wafer cassettes C smaller than the FOUP 10 in a multi-layer manner (in other words, store a plurality of wafer cassettes C in the height direction H). The wafer transfer robot 4 performs a wafer loading / unloading process on the mounting table 21 of the loading device 2 with respect to the FOUP 10. The wafer cassette transfer device 5 moves the wafer cassette C stored in a certain layer of the wafer cassette rack 3 to another layer having a different height (i.e., the wafer cassette transfer device 5 moves the wafer cassette C in the height direction H). The wafer cassette C is a well-known open cassette that can store a plurality of wafers in a multi-layer manner (by arranging the wafers in the height direction H).

[0036] The housing 1 has a hollow rectangular parallelepiped shape and includes a front wall 11, a rear wall 12, a top wall 13, a bottom plate base 14, and a pair of left and right side walls (not shown) that extend forward from the vicinity of the left and right edges of the rear wall 12, respectively. The housing 1 can keep its internal space 1S in a substantially sealed state and keep the internal space 1S under positive pressure (details will be described later). At a predetermined height position of the front wall 11, a housing window portion (not shown) that penetrates in the front-rear direction D is formed. Wafers can be put in and taken out through this housing window portion. In the present embodiment, a plurality of housing window portions (three housing window portions in the illustrated example) are formed at a predetermined interval in the width direction W on the front wall 11. As Figure 2 andFigure 3 As shown, an emergency stop (EMO) button 11b and a monitor 11c are installed on the front wall 11.

[0037] As Figure 3 and Figure 4 As shown in (a) to (d), the loading device 2 includes a plate-shaped upright base 22 arranged in an upright posture, a loading device door 23 for opening and closing an opening 22a formed in the upright base 22, and a mounting table 21 provided on the upright base 22 in a substantially horizontal posture. The loading device 2 is installed on the front surface of the housing 1. That is, the loading device 2 is arranged such that the upright base 22 is in close contact with the front wall 11 of the housing 1 from the front side of the housing 1. In this arrangement state, the opening 22a formed in the upright base 22 and the housing window portion formed in the front wall 11 of the housing 1 overlap (communicate) with each other in the front-rear direction D.

[0038] The mounting table 21 is installed on the upper portion of a horizontal base 24 (support base), and the horizontal base 24 is arranged in a substantially horizontal posture at a position slightly higher than the center of the upright base 22 in the height direction H. The mounting table 21 can support the FOUP 10 in an orientation where the FOUP door Y2 faces the loading device door 23. In addition, the mounting table 21 is configured to be movable back and forth relative to the upright base 22. Specifically, the mounting table 21 can move back and forth between a predetermined docking position where the FOUP door Y2 is adjacent to the opening 22a of the upright base 22 (see Figure 4 (c)) and a position where the FOUP door Y2 is spaced apart from the upright base 22 by a greater predetermined distance than the docking position (see Figure 4 (a) and (b)). The mounting table 21 includes a plurality of protrusions (pins) protruding upward (not shown). By engaging these protrusions with holes (not shown) formed on the bottom surface of the FOUP 10, the FOUP 10 is positioned on the mounting table 21. In addition, the mounting table 21 includes a locking claw (not shown) for fixing the FOUP 10. By hooking and fixing the locking claw to a locked portion (not shown) formed on the bottom surface of the FOUP 10 to bring it into a locked state, the FOUP 10 can be guided and fixed at an appropriate position on the mounting table 21 in cooperation with the positioning protrusions. In addition, by releasing the locked state of the locking claw relative to the locked portion formed on the bottom surface of the FOUP 10, the FOUP 10 can be separated from the mounting table 21.

[0039] The loading device door 23 includes a connection mechanism 26 for connecting the loading device door 23 and the FOUP door Y2, and is configured to move along a predetermined movement path while holding the FOUP door Y2 through the connection mechanism 26. The connection mechanism 26 can be switched between a lid connection state in which the loading device door 23 and the FOUP door Y2 are connected and a lid connection release state in which the connection between the loading device door 23 and the FOUP door Y2 is released. In the lid connection state, the FOUP door Y2 can be removed from the FOUP body Y3. In the lid connection release state, the FOUP door Y2 is attached to the FOUP body Y3. The loading device door 23 is configured to be movable at least between Figure 4 the fully closed position (C) shown in (a) etc. and the open position (not shown). The fully closed position (C) is the position of the loading device door 23 when the internal space YS of the FOUP body Y3 is sealed by the FOUP door Y2. The open position is the position of the loading device door 23 when the FOUP door Y2 is separated from the FOUP body Y3 and the internal space YS of the FOUP body Y3 is opened toward the internal space 1S of the housing 1. The loading device 2 moves the loading device door 23 from the fully closed position to the open position while maintaining the upright posture of the loading device door 23, and can further move the loading device door 23 downward from the open position to the Figure 4 fully open position (O) shown in (d). This movement of the loading device door 23 is achieved by a door movement mechanism 27 installed in the loading device 2. In addition, the loading device 2 includes a movement restricting portion (not shown) that restricts the movement of the FOUP 10 positioned on the mounting table 21 at the docking position away from the upright base 22.

[0040] The loading device 2 includes a cleaning device P (see Figure 4(a) to (d)). The cleaning device P is configured to inject an inert gas such as nitrogen or a cleaning gas such as dry air into the internal space YS of the FOUP 10 to replace the atmosphere in the internal space YS of the FOUP 10 with the cleaning gas. The cleaning device P can replace the atmosphere in the internal space YS of the FOUP 10 with the same type of inert gas as the inert gas supplied to the internal space 1S of the housing 1 from the gas introduction device 6 described later. The cleaning device P includes a plurality of cleaning nozzles 2N (gas supply / discharge devices) arranged at predetermined positions on the mounting table 21 while their upper ends can be exposed. These cleaning nozzles 2N are attached to appropriate positions on the mounting table 21 according to the positions of the ports Y4 formed on the bottom surface of the FOUP 10 and can be connected to the ports Y4. Using such a cleaning device P, the following bottom cleaning process is performed. First, the cleaning device P makes some of the ports Y4 serve as "supply ports" and injects a suitably selected cleaning gas such as nitrogen, inert gas, or dry air into the FOUP 10 through the cleaning nozzles 2N connected to the supply ports. At the same time, the cleaning device P makes the remaining ports Y4 serve as "exhaust ports" and discharges the gas in the FOUP 10 through the cleaning nozzles 2N connected to the exhaust ports. As a result, the FOUP 10 is filled with the cleaning gas.

[0041] The loading device 2 of the present embodiment includes a mapping member (not shown) capable of detecting the presence / absence and storage posture of the wafer in the FOUP 10.

[0042] A plurality of such loading devices 2 (three loading devices 2 in the illustrated example) are arranged side by side along the width direction W of the housing 1 on the front side of the housing 1.

[0043] As Figure 1 and Figure 2 shown, the wafer cassette rack 3 includes a wafer cassette rack base 31 and a rack body 32 supported by the wafer cassette rack base 31. The rack body 32 is formed by integrally assembling a plurality of rack plates (not shown) arranged in a layered manner and a rack frame having side walls capable of supporting both ends of each rack plate. The wafer cassette rack 3 of the present embodiment can store 10 layers of wafer cassettes C in the height direction H. The lowermost mounting space (first layer mounting space) of the wafer cassette C is provided on the upper surface 31a of the wafer cassette rack base 31, and the second and subsequent wafer cassettes C from the bottom are respectively mounted on the rack plates. In the present embodiment, the upper surface 31a of the wafer cassette rack base 31 and the upper surface of the mounting table 21 of the loading device 2 are set at substantially the same height position.

[0044] The separation distance between the cassettes C stored in the cassette rack 3 in a multi-layered manner in the height direction H can be equally spaced. Alternatively, the separation distance between the racks can be appropriately changed in consideration of, for example, the arrangement positions of the components (such as beams (not shown), etc.) constituting the cassette rack 3. The wafer storage X of the present embodiment is arranged such that the same number of columns of cassettes C as the number of loading devices 2 can be placed on the cassette rack 3. That is, in the present embodiment, a cassette rack 3 that can place three columns of cassettes C in the width direction W is applied.

[0045] The wafer transfer robot 4 is installed between the front wall 11 of the housing 1 and the cassette rack 3. The wafer transfer robot 4 can perform the process of taking out a wafer from the FOUP 10 mounted on the mounting table 21 of the loading device 2 and transporting the wafer to the cassette C stored in the cassette rack 3. In addition, the wafer transfer robot 4 can perform the process of taking out a wafer from the cassette C of the cassette rack 3 and placing the wafer back into the FOUP 10. As Figure 2 shown, the wafer transfer robot 4 includes, for example: an arm mechanism 42 in which a wafer gripping portion (hand) is mounted at the tip of a plurality of interconnected link elements so as to be able to rotate horizontally; and a base portion configured to support the arm mechanism 42. The wafer transfer robot 4 has a link structure (hinged structure) whose shape changes between a folded state in which the arm length of the arm mechanism 42 is minimized and an extended state in which the arm length is longer than that in the folded state. A plurality of individually controllable wafer gripping portions can be mounted at the tip of the arm mechanism 42 in a multi-layered shape in the height direction H.

[0046] As Figure 5 shown, the space in the internal space 1S of the housing 1 where the wafer transfer robot 4 is installed is a space in front of the cassette rack 3 in the front-rear direction D and a space (wafer transfer space) serving as the wafer transfer chamber 4S. In the present embodiment, as Figure 1 etc. shown, one wafer transfer robot 4 and one wafer aligner A are installed in the wafer transfer chamber 4S.

[0047] The wafer transfer robot 4 includes an exhaust box 44 that communicates with the internal space of the base portion 43. Dust generated from a drive mechanism (the drive mechanism of the arm mechanism 42) etc. installed in the base portion 43 is forcibly collected in the exhaust box 44 set to a negative pressure (see Figure 5 ).

[0048] As Figure 1 and Figure 2As shown, the cassette transfer device 5 is configured to move the cassette C stored in the cassette rack 3 to at least one layer with a different height in the cassette rack 3. The cassette transfer device 5 includes a cassette transfer arm 51 that can move in the front-rear direction D and the height direction H, and a cassette transfer device frame 52 that supports the cassette transfer arm 51. In the present embodiment, the cassette transfer arm 51 has a hand portion with a bifurcated tip portion. However, the present invention is not limited thereto. In addition, the cassette transfer device frame 52 has a substantially rectangular parallelepiped shape and includes a drive mechanism installed therein to move the cassette transfer arm 51 up and down and back and forth. In the cassette transfer device 5, as Figure 2 shown, the same number of cassette transfer arms 51 as the number of columns of the cassette C (three columns in the present embodiment) that can be placed on the cassette rack 3 are arranged side by side in the width direction W. In addition, the cassette transfer device 5 is configured to transfer the cassette C facing each column of the cassette transfer arm 51 in the same column in the height direction H. As Figure 5 shown, a space (cassette transfer space) serving as a cassette transfer chamber 5S that allows the cassette C to move in the height direction H is formed between the cassette transfer device frame 52 and the cassette rack 3.

[0049] As Figure 1 , Figure 2 and Figure 5 shown, the wafer storage X includes a gas introduction device 6, an exhaust device 7, and a fan filter unit (FFU) 8. The gas introduction device 6 supplies an inert gas into the housing 1. The exhaust device 7 discharges the gas in the internal space 1S of the housing 1. The fan filter unit 8 passes the inert gas supplied from the gas introduction device 6 and generates a downward air flow (laminar flow) in the space extending from the cassette transfer device 5 to the front wall 11 of the housing 1 (the space including the cassette transfer chamber 5S and the wafer transfer chamber 4S).

[0050] The gas introduction device 6 includes a mass flow controller 61 (MFC) and a gas introduction pipe 62 (see Figure 5)。The mass flow controller 61 is installed at a predetermined position behind the wafer cassette transfer device 5 in the housing 1 to control the flow rate while measuring the mass flow rate of the fluid. The gas introduction pipe 62 is a pipe for supplying an inert gas (nitrogen in this embodiment) to the internal space 1S of the housing 1 via the mass flow controller 61. The gas introduction pipe 62 includes a gas introduction start-end pipe 63, a gas introduction vertical pipe 64, and a gas introduction horizontal pipe 65. The gas introduction start-end pipe 63 is a pipe installed at the rear end portion of the housing 1 and communicating with the valve 61v of the mass flow controller 61. The gas introduction vertical pipe 64 extends from the front end portion (top end portion) of the gas introduction start-end pipe 63 along the inner surface of the rear wall 12 of the housing 1 to near the top wall 13 of the housing 1. The gas introduction horizontal pipe 65 extends from the upper end portion of the gas introduction vertical pipe 64 along the top wall 13 of the housing 1 to near the front wall 11 of the housing 1. The gas introduction horizontal pipe 65 has downward-opening holes (downward holes) formed at a predetermined interval in the front-rear direction. As a result, the inert gas that reaches the gas introduction horizontal pipe 65 from the valve 61v of the mass flow controller 61 via the gas introduction start-end pipe 63 and the gas introduction vertical pipe 64 is supplied to the internal space 1S of the housing 1 from the downward holes of the gas introduction horizontal pipe 65 (see Figure 5 ).

[0051] The fan filter unit 8 is a combination of a fan and a filter and has an air purification function. In the wafer storage X of this embodiment, the fan filter unit 8 is arranged in a region extending from the upper end portion of the wafer cassette transfer device 5 (the upper end portion of the wafer cassette transfer device frame 52) to the inner surface of the front wall 11 of the housing 1. The inert gas supplied to the internal space 1S of the housing 1 by the gas introduction device 6 is sent as a highly clean downward air flow (laminar flow) to the wafer cassette transfer chamber 5S and the wafer transfer chamber 4S through the fan filter unit 8.

[0052] As Figure 5 shown, the exhaust device 7 includes an automatic pressure controller (APC) 71 and an exhaust port 72 communicating with the valve 71v of the automatic pressure controller 71. The automatic pressure controller 71 is installed in the housing 1 on the rear side of the wafer cassette transfer device 5 and on the lower side of the mass flow controller 61 of the gas introduction device 6. The gas in the downward air flow generated by the fan filter unit 8 reaches near the bottom plate base 14 of the housing 1 through the space between the wafer cassette transfer device 5 and the front wall 11 of the housing 1 and flows toward the discharge port 72. A predetermined amount of gas is discharged to the outside of the housing 1 through the exhaust port 72 and the valve 71v of the automatic pressure controller 71. In this embodiment, through paths 3T, 5T through which the air flow flowing toward the exhaust device 7 can pass are respectively formed at the lower end portion of the wafer cassette rack 3 and the lower end portion of the wafer cassette transfer device 5 (see Figure 2 and Figure 5)。In addition, the exhaust device 7 includes an exhaust cross pipe 73 extending from the exhaust box 44 of the wafer transfer robot 4 toward the exhaust port 72. Dust and the like collected in the exhaust box 44 of the wafer transfer robot 4 are discharged to the outside of the housing 1 through the exhaust cross pipe 73 and the exhaust port 72.

[0053] In the wafer storage X of the present embodiment, a part of the gas flowing toward the exhaust device 7 is discharged, and most of the remaining gas is set to rise along the rear wall 12 of the housing 1. Specifically, as Figure 1 , Figure 2 and Figure 5 shown, a pair of left and right partition walls 15 are installed and erected in the housing 1. A tubular space is formed by the partition walls, the rear wall of the wafer cassette transfer device 5, and the rear wall 12 of the housing 1. In addition, a blower 9 is installed at a position between the wafer cassette transfer device 5 and the rear wall 12 of the housing 1 and higher than the exhaust port 72 of the exhaust device 7. The blower 9 generates an upward air flow in the above-described tubular space. In the housing 1, when the gas in the upward air flow generated by the blower 9 reaches near the top wall 13 of the housing 1, the gas converges with the air flow flowing toward the front wall 11 of the housing 1. Then, the gas, together with the inert gas supplied downward from the gas introduction cross pipe 65 of the gas introduction device 6, passes through the fan filter unit 8 and flows along the downward air flow. As described above, a gas circulation path for circulating most of the inert gas supplied from the gas introduction device 6 is formed in the housing 1.

[0054] In the wafer storage X having such a configuration, the inert gas circulates in the housing 1 to keep the internal space 1S of the housing 1 at a positive pressure, which can prevent the atmosphere outside the housing 1 from entering the inside of the housing 1. Specifically, the automatic pressure controller 71 controls the flow of the gas so that the pressure in the entire gas circulation path is positive with respect to the atmosphere outside the housing 1. More specifically, the pressure in the space (storage area) for storing the wafer cassette C is controlled to be, for example, 10 to 300 Pa (gauge pressure). More preferably, the pressure in the storage area is controlled to be, for example, 10 to 100 Pa (gauge pressure) or a low positive pressure (slight positive pressure). As a result, the space for storing a large number of wafer cassettes C and the space for transferring wafers can be in a highly clean space, and the characteristics of the wafers can be maintained by an atmosphere with a low oxygen concentration (e.g., 10 to 100 ppm) and a low humidity (e.g., a dew point temperature of -50°C or lower).

[0055] Next, with reference to Figure 4 (a) to (d), Figures 6 to 9 the operation process of the wafer storage X according to the present embodiment will be described. In Figures 6 to 9 , for ease of explanation, the front wall 11 and the partition wall 15 of the housing 1 are omitted.

[0056] First, the FOUP 10 is placed on the mounting table 21 of the loading device 2 by a container handling device such as an OHT (see Figure 4 (a)). At this time, for example, the positioning protrusions provided on the mounting table 21 are fitted into the positioning recesses of the FOUP 10 so that the locking claws on the mounting table 21 enter the locked state (locking process). In the present embodiment, the FOUP 10 can be mounted on each of the three mounting tables 21 of the loading device 2 arranged side by side in the width direction W. In addition, a placement sensor (not shown) for detecting whether the FOUP 10 is mounted at a predetermined position on the mounting table 21 can be configured to detect that the FOUP 10 is mounted at a normal position on the mounting table 21.

[0057] In the loading device 2 of the present embodiment, when the FOUP 10 is placed at a predetermined normal position on the mounting table 21, it is detected that the bottom surface portion of the FOUP 10 presses the pressed portion of a pressure sensor mounted on the mounting table 21, for example. Triggered by this, all the cleaning nozzles 2N mounted on the mounting table 21 are moved above the upper surface of the mounting table 21 and connected to the corresponding ports Y4 of the FOUP 10. As a result, each port Y4 is switched from the closed state to the open state. Then, the loading device 2 supplies nitrogen gas, which is an inert gas, into the internal space YS of the FOUP 10 through the cleaning device P and replaces the internal space YS of the FOUP 10 with nitrogen gas ( Figure 4 (b)) (bottom cleaning process). During the bottom cleaning process, the gas in the FOUP 10 is discharged to the outside of the FOUP 10 through the cleaning nozzles 2N connected to the ports Y4 serving as exhaust ports. Figure 4 (b) schematically shows the supply direction of nitrogen gas and the discharge direction of gas in the FOUP 10 during the bottom cleaning process. Through such a bottom cleaning process, the loading device 2 reduces the water concentration and oxygen concentration in the FOUP 10 to predetermined values or less, and makes the environment around the wafer in the FOUP 10 a low humidity environment and a low oxygen environment.

[0058] After the locking process, the loading device 2 of the present embodiment moves the mounting table 21 located at the position shown in Figure 4 (b) to Figure 4(c) The docking position (docking process) shown. Next, the loading device 2 performs a process of holding and fixing the FOUP 10 at least on both sides by using the movement restricting member (clamping process), and switches the connection mechanism 26 to the cover connection state (cover connection process). Further, the loading device 2 performs a process of releasing the sealed state inside the FOUP 10 by moving the FOUP door Y2 together with the loading device door 23 to open the opening 22a of the upright base 22 and the loading / unloading port Y1 of the FOUP 10 (seal release process) (see Figure 4 (d)). The loading device 2 can be configured to perform a mapping process by the mapping member during the process of moving the loading device door 23 from the open position to the fully open position (O). Therefore, the presence / absence and storage posture of the wafers stored and arranged in the FOUP 10 in the height direction H can be sequentially detected.

[0059] By performing the seal release process, the internal space YS of the FOUP main body Y3 and the internal space 1S of the housing 1 communicate with each other. After that, based on the information (wafer position) detected in the mapping process, the wafer transfer robot 4 performs the following wafer transfer process. That is, the wafer transfer robot 4 transfers the wafers in the FOUP 10 to the wafer cassette C stored in the wafer cassette rack 3, and transfers the wafers in the wafer cassette C to the FOUP 10.

[0060] In the wafer storage X, the first layer mounting space of the wafer cassette rack 3 (specifically, the upper surface 31a of the wafer cassette rack base 31) is set as the transfer position for transferring wafers to / from the wafer cassette C by the wafer transfer robot 4. Therefore, before the wafer transfer process (the process of transferring the wafers in the FOUP 10 to the wafer cassette C), the wafer storage X performs the following process. First, for example, as Figure 6 shown, when viewed from the front, the wafer cassette C is not placed on the first layer of the left column of the wafer cassette rack 3 (idle state). In this state, the wafer storage X transports the wafer cassette C stored in the layer above the second layer in the same column (the third layer in the illustrated example) to the first layer of the wafer cassette rack 3 by the wafer cassette transfer device 5 (wafer cassette transfer process) (see Figure 7 ).

[0061] In Figure 6 , the transport path of the wafer cassette C carried by the wafer cassette transfer arm 51 is schematically shown by an arrow.

[0062] As Figure 7As shown, during the wafer transfer process of transferring wafers between the wafer cassette C set on the first layer of the wafer cassette rack 3 and the FOUP 10, the wafer storage X performs the following "next-use wafer cassette transfer process". That is, the wafer storage X transports the wafer cassette C to be used in the next wafer process to the free space in the installation space on the first layer of the wafer cassette rack 3 through the wafer cassette transfer device 5. Figure 7 The state is shown where the wafer cassette C stored in the layer above the second layer in the central column of the wafer cassette rack 3 (the third layer in the example shown) is transported to the center of the installation space on the first layer of the wafer cassette rack 3 as the "next-use wafer cassette". In Figures 7 to 9 , the transfer path of the wafer cassette C carried by the wafer cassette transfer arm 51 is schematically shown by a thicker arrow, and the transfer path of the wafer carried by the wafer transfer robot 4 is schematically shown by a relatively thinner arrow. The wafer transfer robot 4 transports wafers between the FOUP 10 installed on the loading device 2 and the wafer cassette C arranged in multiple layers of the wafer cassette rack 3 and facing the height of the transfer container in the front-rear direction.

[0063] The wafer storage X performs the following sealing process on the FOUP 10 that has completed the wafer transfer process. First, the wafer storage X moves the loading device door 23 to the fully closed position (C) through the door moving mechanism 27 of the loading device 2, and closes the opening 22a of the upright base 22 and the device / unloading port Y1 of the FOUP 10. Subsequently, the loading device 2 performs a process of switching the connection mechanism 26 from the cover connection state to the cover connection release state (cover connection release process). Through this process, the internal space YS of the FOUP 10 enters the sealed state.

[0064] Subsequently, the loading device 2 performs a clamping release process to release the fixed state (clamped state) of the FOUP 10 held by the movement restricting member. Next, the loading device 2 performs a process of moving the mounting table 21 away from the upright base 22 (docking release process), and then releases the state of locking the FOUP 10 by the locking claws on the mounting table 21 (unlocking process). As a result, the FOUP 10 is transported from the mounting table 21 of each loading device 2 to the container transfer device and is transported to, for example, the mounting table of the loading port constituting the EFEM (Equipment Front End Module).

[0065] On the other hand, at an appropriate time after the sealing process is performed by the loading device 2, the wafer cassette C that has undergone the wafer transfer process is transported from the installation space on the first layer of the wafer cassette rack 3 to the original layer installation space through the wafer cassette transfer device 5 (wafer cassette return process). As Figure 8 shown, the wafer cassette return process can be performed during the wafer transfer process using another wafer cassette C different from the target of the wafer cassette return process.

[0066] As described above, the wafer storage X can repeatedly perform a wafer transfer process as needed in a state where a large number of cassette C accommodating wafers in multiple layers or a large number of cassette C not accommodating wafers are stored in the housing 1. Figure 9 The state shown in the FOUP 10 on the loading device 2 is transported to the next process, and the cassette C that has completed the wafer transfer process returns from the first-layer installation space of the cassette rack 3 to the original-layer installation space. Figure 8 The wafer transfer process using the wafer transfer robot 4 is a process of transferring the wafers in the FOUP 10 to the cassette C on the cassette rack 3, or a process of transferring the wafers stored in the cassette C to the FOUP 10. The process to be performed can be appropriately selected. In addition, the wafers in the FOUP 10 can be transferred to the cassette C via the wafer aligner A installed in the wafer transfer chamber 4S, or the wafers in the cassette C can be transferred to the FOUP 10 via the wafer aligner A (see

[0067] and Figure 7 and Figure 8 ). The operation of the wafer storage X is controlled by a controller (not shown).

[0068] As described above, according to the wafer storage X of the present embodiment, an inert gas is supplied into the housing 1 through the gas introduction device 6, and a plurality of cassette C can be stored in the housing 1 maintained at a positive pressure with a low oxygen concentration, a low water concentration, and high cleanliness in multiple layers. As a result, it is possible to prevent the atmosphere from entering from the outside, and the outgassing generated from the wafers after semiconductor processing can be blown downward by the downward airflow generated by the fan filter unit 8, and can be discharged to the outside of the housing 1 through the exhaust device 7. In particular, since the wafer storage X can store a large number of wafers, it is difficult to supply all the inert gas from the outside to form a laminar flow. Therefore, it is effective to suppress an increase in operating costs by forming a circulation path for the inert gas in the internal space 1S of the housing 1.

[0069] In addition, the wafer storage X according to the present embodiment has a structure in which wafers are stored in units of a cassette C capable of accommodating wafers in multiple layers. Therefore, compared with the related-art FOUP storage that houses the entire FOUP 10 therein, dust attached to the outer surface of the FOUP 10 and moisture introduced onto the outer surface of the FOUP can be prevented from being released into the storage. Accordingly, a decrease in the cleanliness of the storage can be suppressed. In addition, with such a structure, it is possible to prevent or suppress the entry of exhaust gas or the like generated from the wafers after semiconductor processing into the storage and the diffusion thereof in the storage. As a result, it is possible to prevent or suppress the contamination of the wafers in the housing 1 of the wafer storage X or in the internal space YS of the FOUP 10 communicating with the internal space 1S of the housing. That is, the wafer storage X according to the present embodiment can always maintain a high cleanliness around the wafers and can prevent or suppress the attachment of particles and moisture to the wafer surfaces. Therefore, the atmosphere around the wafers in the storage can be further improved.

[0070] In addition, the wafer storage X of the present embodiment has a structure in which a cassette C smaller than the FOUP 10 is generally used to store wafers. Therefore, compared with the related-art storage that houses the entire FOUP therein, the size of the entire wafer storage X can be reduced and the occupied area of the wafer storage X can be decreased. Alternatively, compared with the related-art storage that houses the entire FOUP therein, the number of wafers that can be accommodated in the wafer storage X can be increased while suppressing an increase in the size of the entire device. In addition, the wafer storage X according to the present embodiment has a structure in which the cassette C stored in the cassette rack 3 is transported within the housing 1. Therefore, compared with the related-art storage that transports the entire FOUP in the housing, the transport space in the housing can be made compact.

[0071] In addition, the wafer storage X is configured such that the cassettes C can be stored in multiple columns along the width direction W in the cassette rack 3, and includes a loading device 2 and a cassette transfer arm 51 corresponding to the number of columns. Therefore, the transport process of the cassettes C and the wafer transfer process can be effectively performed.

[0072] In addition, in the cassette C stored in the cassette rack 3, the cassette C disposed at the height position facing the FOUP 10 mounted on the mounting table 21 of the loading device 2 in the front-rear direction D (specifically, the cassette C mounted in the first-layer mounting space) is set as the cassette C to which the wafer is transported by the wafer transfer robot 4. That is, the wafer transfer robot 4 transports the wafer between the FOUP 10 mounted on the loading device and the cassette C in the layer of the multi-layer of the cassette rack 3 that faces the height of the FOUP 10 in the front-rear direction. Therefore, for example, compared with a configuration in which the wafer is transported from the FOUP 10 to a cassette C stored in the cassette rack 3 by the wafer transfer robot 4 and the cassette C is not at the height position facing the FOUP 10 mounted on the mounting table 21 of the loading device 2 in the front-rear direction, the height of the transport position of the wafer transported by the wafer transfer robot 4 can be limited within a predetermined range. Therefore, the time taken by the wafer transfer robot 4 to transfer the wafer between the FOUP 10 and the cassette C can be shortened.

[0073] As a specific storage form of the cassette C in the cassette rack 3 serving as the wafer storage X, there may be a form in which the cassette C accommodating frequently used wafers is stored in a mounting space closer to the first-layer mounting space. As a result, the access time of the wafers that are desired to be used preferentially can be shortened. In addition, wafers with a relatively high degree of contamination (wafers that generate a large amount of outgassing) are set to be stored in the mounting space below the wafers with a relatively low degree of contamination, which can suppress the spread of contamination. In addition, wafers that have degassed by long-term storage in the housing can be moved to the upper layer.

[0074] According to the wafer storage X of the present embodiment, the storage positions in the cassette rack 3 can be divided according to the type and state of the wafers, the semiconductor processing process applied to the wafers, and the like. Appropriate partition plates can be installed in the cassette rack 3 to define the partition range.

[0075] In addition, in the present embodiment, the loading device 2 of the wafer storage X has the same or similar configuration as the loading port constituting the EFEM, which can save the labor and time for designing and manufacturing a new loading device.

[0076] Although the embodiments of the present invention have been described above, the present invention is not limited to the configurations of the above embodiments. For example, the number of layers of the cassette rack (the number of wafer mounting spaces in the height direction) and the number of columns of the cassette rack (the number of wafer mounting spaces in the width direction) can be appropriately changed.

[0077] As a cassette transfer device, a device provided with a cassette transfer arm can be used. In addition to being able to move up and down, the cassette transfer arm can also move in the width direction of the housing. By using such a cassette transfer device, the cassette stored in the cassette rack can be moved to different columns by the cassette transfer arm.

[0078] In addition, as the cassette rack, a rotating rack that rotates in a horizontal plane can be used. In this case, for example, a plurality of cassette mounting spaces can be provided at a predetermined angular pitch in the circumferential direction orthogonal to the height direction H (for example, four cassette mounting spaces are provided at an interval of 90 degrees). Then, the cassette mounted in each cassette mounting space can be configured to take a rotational angle posture facing the wafer transfer robot or the cassette transfer arm. In this way, the wafer transfer robot or the wafer transfer arm can enter the cassette mounting space. In this way, the wafer transfer process and the cassette transfer process can be effectively performed.

[0079] In addition, as the cassette stored in the cassette rack, a cassette that can be accessed from a total of four directions (that is, one side and the other side in the width direction W and one side and the other side in the front-rear direction D) can also be used.

[0080] The cassette transfer device can be capable of storing cassettes in multiple layers along the height direction of one column.

[0081] In addition, the cassette mounted in the mounting space of the layer other than the first layer of the cassette rack can be configured to be located at the height position facing the transfer container mounted on the loading device in the front-rear direction. In this configuration, the cassette located at this height position can also be set as the "cassette to be transferred by the wafer transfer robot". That is, the wafer storage of the present invention also has the function of setting the cassette placed in the second layer or higher layer as the "cassette to be transferred by the wafer transfer robot".

[0082] In the above embodiment, a FOUP is used as the transfer container. However, in the present invention, transfer containers other than FOUP can also be used, such as MAC (Multi-Application Carrier), H-MAC (Horizontal MAC), FOSB (Front-Opening Shipping Box), etc.

[0083] In addition, as the container transfer device, an appropriate transfer device other than OHT can be used. OHS (Overhead Hoist Shuttle), RGV (Rail Guided Vehicle), AGV (Automated Guided Vehicle), etc. can also be used. RGV and AGV are container transfer devices that run on the floor side of the factory. When the container transfer device is an RGV, rails (tracks) are installed on the floor of the factory or the like.

[0084] In addition, the wafer transfer robot may have a traveling axis capable of traveling in the width direction of the housing (parallel direction of the loading device). For example, when the number of columns of the loading devices arranged side by side in the width direction of the housing is large, it is preferable to use a wafer transfer robot having a traveling axis extending in the width direction of the housing.

[0085] In the above embodiment, nitrogen is taken as an example of the inert gas supplied into the housing. However, the present invention is not limited thereto. Dry gas, argon, etc. can be used. Similarly, the inert gas used for the bottom cleaning process is not limited to nitrogen. Alternatively, the gas supplied into the housing does not necessarily have to be an inert gas and can be, for example, dry air. Accordingly, a low-humidity environment that is not an environment with a low oxygen concentration can be achieved.

[0086] In addition, in the process of moving from the fully closed position to the fully open position, the container door (FOUP door) can be temporarily in an inclined posture (accompanied by an operation of drawing a partial arc trajectory).

[0087] If the wafer alignment process can be omitted, the cost can be reduced by adopting a configuration in which no wafer aligner is provided in the wafer transfer space.

[0088] In addition, the gas introduction device can be configured by using an appropriate device other than the mass flow controller (MFC) that controls the flow rate while measuring the mass flow rate of the fluid. In addition, the exhaust device can be constituted by using an appropriate device other than the automatic pressure control device (APC) that maintains a positive pressure inside according to the exhaust volume. For example, a configuration in which the inert gas is introduced through the return pipe constituting the gas circulation path can be adopted. If the inert gas is introduced through the return pipe, when the flow rate is large, a backflow may be generated in the housing. Therefore, by introducing the inert gas into the housing from a position higher than the fan filter unit, the problem of backflow can be solved. In addition, by introducing the inert gas into the housing from a position higher than the fan filter unit, the air pressure at the position higher than the fan filter unit is locally increased, and thus the laminar flow is not disturbed.

[0089] The gas circulation path does not necessarily have to be formed in the housing. That is, the wafer storage can be configured such that the gas does not circulate and all the gas supplied into the housing through the gas introduction device is exhausted through the exhaust device.

[0090] The number of wafers that each wafer cassette can accommodate is, for example, 25, but a wafer cassette capable of accommodating a number other than 25 in a multi-layer manner can also be used.

[0091] A chemical filter can be installed around the return pipe and the blower. In addition, the return pipe can be installed on the side surface of the housing.

[0092] In the wafer storage, the fan filter unit is configured to generate a downward air flow as a laminar flow. However, the present invention is not limited thereto. The wafer storage may be configured to generate a laminar flow flowing in a horizontal direction in, for example, a wafer transfer space and a cassette transfer space.

[0093] As a loading device, a dedicated loading device different from the loading port used in the EFEM may be used.

[0094] The wafer storage according to the present invention may also be used as a sorter. In this case, it is preferable to provide a wafer front / back flipper together with a wafer aligner in the wafer transfer space.

[0095] A configuration may be adopted in which wafers are stored in the housing without having to use a cassette, or a configuration in which the hand of the wafer transfer device can hold and transfer a plurality of wafers at the same time. In addition, by providing a vertical movement mechanism for the wafer transfer robot, the wafer transfer robot can enter each shelf and replace wafers. Specifically, as Figure 10 shown, the transfer system 1a may include a movement mechanism 80. For example, the movement mechanism 80 may include a pair of columnar members 81 erected on the front side and the left and right sides of the cassette shelf 3, and a bottom plate member 82 arranged substantially horizontally so as to be movable up and down along the columnar members 81 by a motor (not shown) or the like. A wafer transfer robot 4, a wafer aligner A, and a buffer storage 83 capable of temporarily storing a plurality of wafers may be arranged on the bottom plate member 82. The wafer transfer robot 4 can move wafers between the FOUP 10 and the buffer storage 83, and further move wafers between the buffer storage 83 and the cassette shelf 3. The transfer system 1a may not include a cassette transfer device 5 (see Figure 2 ), but may include a vertical plate 91 formed with a passage 92 through which gas can pass. A fan filter unit 84 that generates a downward air flow (laminar flow) may be attached to the bottom plate member 82. As a result, for example, the diffusion of dust generated when the bottom plate member 82 moves up and down can be suppressed.

[0096] In addition, as another modification of the transfer system 1a, as Figure 11 shown, in the transfer system 1b, a wafer transfer robot 4, a movement mechanism 80, etc. may be additionally installed on the rear side of the cassette shelf 3.

[0097] In addition, the specific configuration of each component is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit of the present invention.

[0098] Description of reference numerals

[0099] 1: Housing

[0100] 2: Loading device

[0101] 3: Wafer cassette rack

[0102] 4: Wafer transfer robot

[0103] 4S: Wafer transfer chamber (wafer transfer space)

[0104] 5: Cassette transfer device

[0105] 5S: Cassette transfer chamber (cassette transfer space)

[0106] 8: Fan filter unit

[0107] 10: FOUP (transfer container)

[0108] X: Wafer storage

Claims

1. A wafer storage device, which comprises: a housing; a loading device, which is mounted on the front surface of the housing and is configured to mount a transfer container capable of accommodating a plurality of wafers; a cassette rack, which is arranged in the housing and is configured to store a plurality of cassettes in a multi-layer manner, and the plurality of cassettes are configured to store a plurality of wafers in a multi-layer manner; a wafer transfer robot, which is configured to load and unload wafers between the transfer container mounted on the loading device and the cassettes stored in the cassette rack; a cassette transfer device, which is configured to move a cassette stored in a predetermined layer among the multi-layers of the cassette rack to a layer at least different in height from the predetermined layer; a fan filter unit, which is configured to generate a laminar flow in a wafer transfer space of the housing where the wafer transfer robot is arranged and in a cassette transfer space of the housing where the cassette transfer device is arranged; a return space, which is mounted in the housing between the rear wall of the housing and the cassette transfer device; and a blower, which is mounted in the return space and is configured to generate an upward airflow that flows toward the fan filter unit in the return space, wherein the fan filter unit is mounted in the housing, wherein a circulation path for gas circulation is formed in the housing, and the circulation path includes the wafer transfer space, the cassette transfer space, and the return space, and wherein when the transfer container mounted on the loading device is in close contact with the upright base of the loading device, the door of the transfer container opens, and the wafer transfer robot only unloads wafers from the transfer container and loads the wafers into the cassette.

2. The wafer storage device according to claim 1, wherein the wafer transfer robot is configured to transfer wafers between the transfer container mounted on the loading device and the cassette in a layer of the multi-layers of the cassette rack that faces the height of the transfer container in the front-rear direction.

3. The wafer storage device according to claim 1, wherein the front wall of the housing, the wafer transfer space, the cassette transfer space, the return space, and the rear wall are sequentially arranged in the internal space of the housing in the front-rear direction.

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