US20140157722A1 - Lid opening/closing system for closed container, and substrate processing method using the same - Google Patents

Lid opening/closing system for closed container, and substrate processing method using the same Download PDF

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Publication number
US20140157722A1
US20140157722A1 US14095173 US201314095173A US2014157722A1 US 20140157722 A1 US20140157722 A1 US 20140157722A1 US 14095173 US14095173 US 14095173 US 201314095173 A US201314095173 A US 201314095173A US 2014157722 A1 US2014157722 A1 US 2014157722A1
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Prior art keywords
aperture
gas
container
lid
pod
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US14095173
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Tadamasa Iwamoto
Jun Emoto
Toshihiko Miyajima
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TDK Corp
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TDK Corp
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    • BPERFORMING OPERATIONS; TRANSPORTING
    • B65CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
    • B65BMACHINES, APPARATUS OR DEVICES FOR, OR METHODS OF, PACKAGING ARTICLES OR MATERIALS; UNPACKING
    • B65B29/00Packaging of materials presenting special problems
    • HELECTRICITY
    • H01BASIC ELECTRIC ELEMENTS
    • H01LSEMICONDUCTOR DEVICES; ELECTRIC SOLID STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H01L21/00Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
    • H01L21/67Apparatus specially adapted for handling semiconductor or electric solid state devices during manufacture or treatment thereof; Apparatus specially adapted for handling wafers during manufacture or treatment of semiconductor or electric solid state devices or components ; Apparatus not specifically provided for elsewhere
    • H01L21/677Apparatus specially adapted for handling semiconductor or electric solid state devices during manufacture or treatment thereof; Apparatus specially adapted for handling wafers during manufacture or treatment of semiconductor or electric solid state devices or components ; Apparatus not specifically provided for elsewhere for conveying, e.g. between different workstations
    • H01L21/67763Apparatus specially adapted for handling semiconductor or electric solid state devices during manufacture or treatment thereof; Apparatus specially adapted for handling wafers during manufacture or treatment of semiconductor or electric solid state devices or components ; Apparatus not specifically provided for elsewhere for conveying, e.g. between different workstations the wafers being stored in a carrier, involving loading and unloading
    • H01L21/67772Apparatus specially adapted for handling semiconductor or electric solid state devices during manufacture or treatment thereof; Apparatus specially adapted for handling wafers during manufacture or treatment of semiconductor or electric solid state devices or components ; Apparatus not specifically provided for elsewhere for conveying, e.g. between different workstations the wafers being stored in a carrier, involving loading and unloading involving removal of lid, door, cover
    • HELECTRICITY
    • H01BASIC ELECTRIC ELEMENTS
    • H01LSEMICONDUCTOR DEVICES; ELECTRIC SOLID STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H01L21/00Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
    • H01L21/67Apparatus specially adapted for handling semiconductor or electric solid state devices during manufacture or treatment thereof; Apparatus specially adapted for handling wafers during manufacture or treatment of semiconductor or electric solid state devices or components ; Apparatus not specifically provided for elsewhere
    • H01L21/677Apparatus specially adapted for handling semiconductor or electric solid state devices during manufacture or treatment thereof; Apparatus specially adapted for handling wafers during manufacture or treatment of semiconductor or electric solid state devices or components ; Apparatus not specifically provided for elsewhere for conveying, e.g. between different workstations
    • H01L21/67763Apparatus specially adapted for handling semiconductor or electric solid state devices during manufacture or treatment thereof; Apparatus specially adapted for handling wafers during manufacture or treatment of semiconductor or electric solid state devices or components ; Apparatus not specifically provided for elsewhere for conveying, e.g. between different workstations the wafers being stored in a carrier, involving loading and unloading
    • H01L21/67775Docking arrangements

Abstract

The partial pressure of an oxidizing gas within a FOUP fixed to a FIMS system and placed in an open state is prevented from increasing with the lapse of time. To that end, a gas supply port is arranged in the bottom face of the FOUP to enable nitrogen supply into the FOUP through the gas supply port with a pod mounted on the FIMS system. A nitrogen supply system for supplying nitrogen with the FOUP mounted is controlled so as to make a nitrogen supply at such a low flow rate and pressure as to be able to prevent dust or the like having such sizes as to possibly cause problems in wiring lines to be formed on a wafer from being stirred up from the gas supply port or the like.

Description

  • This application claims the benefit of Japanese Patent Application Nos. 2012-264903 filed Dec. 4, 2012, 2013-129664 filed Jun. 20, 2013, U.S. provisional Application No. 61/842,600 filed Jul. 3, 2013 and Japanese Patent Application No. 2013-243838 filed Nov. 26, 2013, which are hereby incorporated by reference herein in their entirety.
  • BACKGROUND OF THE INVENTION
  • 1. Field of the Invention
  • The present invention relates to a so-called FIMS (Front-Opening Interface Mechanical Standard) system used when wafers held in a transfer container referred to as a pod are transferred between semiconductor processing apparatuses in a semiconductor manufacturing process or the like. More specifically, the present invention relates to a FIMS system, namely, a lid opening/closing system, in which a pod referred to as a FOUP (Front-Opening Unified Pod) which is a closed container for housing wafers is mounted and the lid of the pod is opened/closed to transfer wafers thereto/therefrom, and which includes a purge mechanism for purging the interior of the pod.
  • 2. Description of the Related Art
  • Conventionally, a semiconductor manufacturing process has been carried out in a so-called clean room in which semiconductor wafers are handled and the interior of which is highly cleaned up. From the viewpoint of coping with the increase of a wafer size and reducing costs required for the management of the clean room, however, there has recently been adopted a technique for keeping, in a highly clean state, only the interior of a processing apparatus, a pod (wafer container), and minute spaces, i.e., minienvironment where wafers are transferred from the pod to the processing apparatus.
  • The pod is comprised of a substantially cubic main body including shelves capable of holding a plurality of wafers inside the pod with the wafers placed parallel to and separately from one another and an aperture formed in one of faces constituting the outer face of the pod to take wafers in and out, and a lid for closing the aperture. The pod in which the face where this aperture is formed is located on one lateral side (a face right opposite a minute space) of the pod, rather than in the bottom face thereof, is generically referred to as a FOUP (front-opening unified pod). The present invention is primarily directed at a system configuration using this FOUP.
  • The abovementioned minute space includes a first aperture facing the aperture of the pod, a door for closing the first aperture, an aperture provided on the semiconductor processing apparatus side, and a transfer robot which steps into the pod from the first aperture to hold a wafer and passes through the processing apparatus-side aperture to carry the wafer to the processing apparatus side. The system configuration having the minute space formed therein also includes a mounting stage for supporting the pod so that the aperture of the pod faces the front of the door.
  • Positioning pins to be fitted into positioning holes provided in the bottom face of the pod to define the mounting position of the pod and a clamp unit to be engaged with a portion to be clamped provided in the bottom face of the pod to fix the pod onto the mounting stage are arranged on the top face of the mounting stage. Under normal conditions, the mounting stage can move back and forth over a predetermined distance in the direction of the door. When wafers inside the pod are transferred to the processing apparatus, the pod is moved, while being placed on the mounting stage, until the lid of the pod comes into contact with the door. After the contact, the lid is removed from the aperture of the pod by the door. By these operations, the interiors of the pod and the processing apparatus are communicated with each other through the minute space. Thereafter, wafer transfer operation is performed repeatedly. A system including the mounting stage, the door, the first aperture, the door opening/closing mechanism, and walls constituting part of the minute space in which the first aperture is formed is generically referred to as a FIMS (front-aperture interface mechanical standard) system.
  • Here, the interior of the pod in a state of containing wafers or the like is generally filled with dry nitrogen or the like controlled to a high degree of cleanness, thereby preventing the ingress of contaminants, oxidizing gases and the like into the pod. When wafers inside the pod are taken into various types of processing apparatus to perform predetermined treatments on the wafers, however, the interiors of the pod and the processing apparatus are constantly kept in a state of being communicated with each other. A fan and a filter are disposed in the upper section of a chamber in which the transfer robot is located to introduce clean air, the particles and like of which are controlled, into the chamber. If such air goes into the pod, however, there arises the possibility that a wafer surface is oxidized due to oxygen or moisture in the air. In addition, along with the miniaturization and performance enhancement of semiconductor devices, attention is being paid to oxidization due to oxygen or the like getting inside the pod which has been not so problematic before.
  • These oxidizing gases form ultrathin oxide films on various layers formed on a wafer surface or a surface of the wafer. Thus, there has been the possibility of fine elements failing to have desired performance due to the presence of such oxide films. As a countermeasure, it is conceivable to prevent the ingress of gases, the oxygen partial pressure and the like of which are not controlled, into the pod from the outside. As a specific method, Japanese Patent Publication Nos. 4301456 or 4309935 discloses a system configuration in which a nozzle for supplying an inert gas, such as nitrogen, is arranged in a region adjacent to the aperture of a pod in a FIMS system. The inert gas is supplied from the gas supply nozzle into the pod whose aperture is opened by removing the lid of the pod, thereby reducing oxygen concentration within the pod. In addition, in a system configuration disclosed in Japanese Patent Application Laid-Open No. 2012-019046 or 2012-135355, an inert gas is supplied from a gas port provided in a wall surface of a pod, thereby reducing oxygen concentration. Yet additionally, Japanese Patent Application Laid-Open No. 2009-290102 discloses a system configuration in which an inert gas is supplied from both an aperture and a wall surface of a pod.
  • In the system configuration disclosed in Japanese Patent Publication No. 4301456 or 4309935, a high-flow rate inert gas can be supplied using an aperture having a sufficiently wide frontage. Accordingly, an inert gas replacement within the pod can be made promptly to easily reduce oxygen concentration to or below a predetermined value. These system configurations require opening the lid in order to make inert gas replacement, however. Accordingly, oxygen concentration control during, for example, a standby time for the pod to wait for processing on the mounting stage is virtually impossible. Here, a high-flow rate inert gas supply is not allowed from cost and safety points of view if, for example, time taken to perform processing on a wafer alone is long. It is thus conceivable to apply a mode of waiting ready with the pod closed by the lid all the time, except the time of taking in and out the wafer. At that time, oxygen concentration in the environment under which each wafer immediately before processing is placed differs, if oxygen concentration within the pod rises due to leakage or the like, if ultrafine wiring lines are formed, or if processing using highly oxidative materials, gases and the like is performed. Accordingly, the characteristics of wafers may differ from one wafer to another. If the pod is increased in size to be compatible with large-diameter wafers, it is generally difficult to keep the internal space of the pod in an airtight state. Thus, there is concern that the leakage of internal gases or the ingress of external gases become increasingly likely to occur during such a standby time.
  • In the case of the system configuration disclosed in Japanese Patent Application Laid-Open No. 2012-019046 or 2012-135355, restrictions arise on the diameter of a gas pipe to be used for inert gas supply since a port has to be provided on a wall surface of the pod. Consequently, in order to supply an amount of inert gas for suitably lowering oxygen concentration, the inert gas has to be supplied at a high flow rate. Since the pod has been increased in size as described above, however, it is increasingly difficult to secure a sufficient amount of inert gas to be supplied. Even if a satisfactory supply of inert gas is possible, the pressure of the supplied gas has to be raised to increase the gas flow rate. This may cause dust or the like adhering to the vicinity of the port to be stirred up by the supplied gas, thus possibly contaminating wafers. In the system configuration disclosed in Japanese Patent Application Laid-Open No. 2009-290102, no consideration is given either to the above-described problems of rise in oxygen concentration during the standby time and to supply of a sufficient amount of inert gas.
  • The present invention has been accomplished in view of the above-described background. Accordingly, an object of the present invention is to provide a lid opening/closing system configured to open/close the lid of a pod which is a closed container and capable of controlling the partial pressure of an oxidizing gas, such as oxygen, within the pod to a predetermined low level and maintaining this level during a so-called standby time.
  • SUMMARY OF THE INVENTION
  • In order to solve the above-described problems, a lid opening/closing system according to the present invention includes a container provided with a substantially box-shaped main body capable of containing an object to be housed and having an aperture in one face of the container main body; a lid separable from the container main body and adapted to cover the aperture to form an enclosed space along with the container main body; and at least one supply port provided on a wall surface of the container main body and capable of supplying a gas from the outside, wherein the object to be housed is allowed to be taken in and out of the container by removing the lid from the container to open the aperture, the system including: a mounting stage on which the container is placed; a minute space located adjacent to the mounting stage to contain a mechanism for transporting the object to be housed with particles controlled; a substantially rectangular first aperture formed in a wall located adjacent to the mounting stage to define part of the minute space, the first aperture being provided in a position where the first aperture is able to face the aperture of the container placed on the mounting stage; a door capable of holding the lid and substantially closing the first aperture, and capable of causing the aperture and the first aperture to be communicated with each other by holding the lid and opening the first aperture; a supply valve for supplying a gas into the container in conjunction with the supply port; and a gas supply system for supplying a predetermined gas through the supply port and the supply valve at a total flow rate of 1 to 60 L/min, or respective flow rate of 1 to 20 L/min with the container placed on the mounting stage.
  • Note that the above-described lid opening/closing system preferably includes opening/closing detection means for detecting the opening/closing of the aperture by the door using the lid, and control means for starting the supply of the predetermined gas to the gas supply system in response to the closure of the aperture detected by the opening/closing detection means. More preferably, the lid opening/closing system further includes a purge nozzle capable of supplying the predetermined gas to the container through the aperture of the container, and the control means performs the start and stop of the supply of the predetermined gas by the purge nozzle in response to the detection of the opening/closing of the lid by the detection means. In addition, the container may further include at least one discharge port provided on a wall surface of the container main body and capable of discharging gases to the outside and the lid opening/closing system may further include a discharge valve for discharging gases from within the container in conjunction with the discharge port.
  • Alternatively, the above-described lid opening/closing system more preferably includes: an enclosure arranged in the minute space in series with the first aperture to cover the moving space of the door and constitute a second minute space, the enclosure having a second aperture through which the first aperture and the minute space communicate with each other and the mechanism for transporting the object to be housed is allowed to pass along with the object to be housed; and a curtain nozzle located in a portion above the upper edge of the first aperture inside the enclosure and capable of supplying the predetermined gas along a direction from the upper edge toward the lower edge of the first aperture, wherein the enclosure more preferably includes a gas outlet port from which the gas is allowed to flow out into the minute space along the direction in which the gas flows.
  • According to the present invention, it is possible to combine inert gas replacement based on a large flow from the aperture and inert gas replacement based on a small flow from a wall surface of the pod to rapidly make inert gas replacement within the pod, and effectively prevent a rise in oxygen concentration also during a standby time or the like with the pod placed on the mounting stage.
  • Further features of the present invention will become apparent from the following description of exemplary embodiments with reference to the attached drawings.
  • BRIEF DESCRIPTION OF THE DRAWINGS
  • FIG. 1 is a perspective view illustrating a schematic configuration of principal parts of a lid opening/closing system according to one embodiment of the present invention.
  • FIG. 2A is a schematic view illustrating a schematic configuration of the lid opening/closing system according to one embodiment of the present invention illustrated in FIG. 1, i.e., a load port, a pod, a lid for the pod, and part of an opener, viewed from a cutting plane thereof perpendicular to the aperture of the pod.
  • FIG. 2B is a schematic view illustrating a state of a first aperture 10 shown in FIG. 2A when viewed from the direction of arrows 2B.
  • FIG. 3 is a schematic view used to describe the direction of supply of a purge gas supplied from each purge nozzle into the pod.
  • FIG. 4A is a schematic view illustrating one step of operation to open/close the lid in the lid opening/closing system illustrated in FIG. 1.
  • FIG. 4B is another schematic view illustrating one step of operation to open/close the lid in the lid opening/closing system illustrated in FIG. 1.
  • FIG. 4C is a schematic view illustrating a state of the first aperture 10 when viewed in the same manner as in FIG. 2B under the condition shown in FIG. 4B.
  • FIG. 5 is an overall side view illustrating a schematic configuration of a commonly-used semiconductor wafer processing apparatus to which the present invention is applied.
  • FIG. 6A is a schematic view illustrating a schematic configuration of the apparatus shown in FIG. 5 when a configuration of a door opening/closing mechanism and the vicinity thereof is enlarged and viewed from a lateral side of the apparatus.
  • FIG. 6B is a schematic view illustrating a schematic configuration of the apparatus when the configuration shown in FIG. 6A is viewed from the transfer chamber side.
  • FIG. 7 is a schematic view illustrating a vertical cross section of the mounting stage, including a gas supply valve, in the lid opening/closing system illustrated in FIG. 1.
  • FIG. 8 is a schematic view illustrating another embodiment of the present invention and a schematic configuration thereof when a configuration of the top face of the mounting stage is viewed from thereabove.
  • DESCRIPTION OF THE EMBODIMENTS
  • Preferred embodiments of the present invention will now be described in detail in accordance with the accompanying drawings.
  • FIG. 1 illustrates a schematic configuration of principal parts of a lid opening/closing apparatus (FIMS, which is hereinafter referred to as the load port) according to a first embodiment of the present invention. FIG. 1 is a schematic perspective view when only the abovementioned mounting stage, the door, the first aperture, part of the door opening/closing mechanism, walls constituting part of the minute space in which the first aperture is formed, the enclosure newly added in the present invention, and components associated therewith are viewed from the minute space side. FIG. 2A is a schematic view illustrating a schematic configuration of the cross sections of the load port and the pod, with the pod mounted on the load port (mounting stage) and the lid of the pod placed in abutment with the door. FIG. 2B illustrates a state of a cross section along the line 2B-2B of FIG. 2A viewed from the minute space side. Note that various components associated with the mounting stage and the like will be described later by referring to FIG. 7.
  • Here, a description will first be made of the pod to be mounted on the load port and a wafer to be housed in the pod (see FIG. 2A). A space for containing a wafer 1, which is an object to be processed, in the pod is formed within a main body 2 a of the pod 2. The pod main body 2 a has a substantially box-like shape having an aperture in one of faces present in a horizontal direction. The pod 2 is provided with a lid 4 for hermetically closing the aperture 2 b of the pod main body 2 a. A rack having a plurality of selves (not illustrated) for vertically stacking wafers 1 horizontally held within the pod main body 2 a is arranged in the pod. The wafers 1 placed on this rack are housed in the pod 2 while being uniformly spaced. The wafers 1 correspond to the objects to be housed in the present invention, the pod 2 corresponds to the container, the pod main body 2 a corresponds to a pod main body defined as having a substantially box-like shape since the basic shape of the pod main body 2 a is boxy, and the aperture 2 b of the pod 2 corresponds to an aperture defined as being substantially rectangular since the basic shape of the aperture 2 b is rectangular. In addition, in the present embodiment, the pod 2 includes a supply port 2 d for gas supply in the bottom face of the pod.
  • The load port 51 according to the present invention includes a mounting stage 53, a door 6, a first aperture 10 functioning as the aperture of the load port, a door opening/closing mechanism 60, a wall 11 which is a member for constituting a minute space (a transfer chamber 52 to be described later) in which the first aperture is formed, and an enclosure 31 newly added in the present invention. The mounting stage 53 includes a movable plate 54 having a flat surface in the upper portion thereof on which the pod 2 is actually mounted and capable of moving the mounted pod toward or away from the first aperture 10. Positioning pins 54 a are embedded in the flat surface of the movable plate 54. The positioning pins 54 a fit into positioning recesses 2 c provided in the bottom face of the pod main body 2 a, thereby uniquely determining the positional relationship between the pod 2 and the movable plate 54.
  • In addition, the mounting stage 53 includes a gas supply valve 53 a located on the front surface of the mounting stage, so as to enable the valve to work in conjunction with a gas supply port 2 d provided in the bottom face of the pod 2 to supply a purge gas to the port. FIG. 7 illustrates a vertical cross section of the mounting stage 53 including the gas supply valve 53 a. The gas supply valve 53 a is comprised of a check valve capable of gas supply in one direction only. In the present embodiment, the gas supply valve 53 a is arranged so as to form a pair in combination with the gas supply port 2 d provided in the bottom face of the pod 2. An inert gas is supplied from an unillustrated inert gas supply system for controlling the pressure and flow rate of the gas to supply or stop supplying the gas to the gas supply valve 53 a trough a gas supply pipe 57. The gas supply valve 53 a is fixed to the mounting stage 53 through a valve up-and-down mechanism 55. The gas supply valve 53 a is moved by the valve up-and-down mechanism 55 between a supply position where the valve can make an inert gas supply to the pod 2 and a standby position below the mounting stage where the valve does not make an inert gas supply and is prevented from contact with the bottom face of the pod 2.
  • The first aperture 10 provided in the wall 11 is formed into such a size, i.e., a rectangular shape one size larger than the rectangular outline of the lid 4, as to allow the lid 4 for closing the pod aperture 2 b to fit into the first aperture 10 when the pod 2 positioned in place on the movable plate 54 is brought closest to the first aperture 10 by the plate. Note that the position at which the movable plate 54 stops the pod 2 may be any position where the door 6 can remove the lid 4 of the pod 2 from the pod main body 2 a. The door 6 is supported to a door opening/closing mechanism 60 through a door arm 6 a. The door opening/closing mechanism 60 allows the door 6 to move between a position at which the door substantially closes the first aperture 10 and a retreat position at which the door completely opens the aperture 10 and an unillustrated transport mechanism can take each wafer 1 in and out of the pod 2 through the aperture 10.
  • The door opening/closing mechanism 60 is comprised of a plurality of unillustrated air cylinders and the like and rotates the door 6 around a fulcrum 61 in conjunction with the door arm 6 a. The rotational operation is performed between the closed position of the first aperture 10 and a position at which the door 6 takes the posture of retreat when driven vertically downward to the retreat position. A surface 6 b of the door 6 on the opposite side of a surface thereof opposed to the first aperture 10 is formed into a rectangular flat surface having such a size as to enable a later-described second aperture 31 a to be closed. The flat surface 6 b is inclined with respect to a surface for closing the first aperture 10. The angle of the inclination is set so as to be parallel to a surface in which the second aperture 31 a is formed, when the door 6 rotates to open the first aperture 10 and takes the posture of retreat. The door opening/closing mechanism 60 includes lid opening/closing detection means for sensing the attachment/detachment of the lid to/from the pod 2 by detecting the position of the door 6 and the retention/non-retention of the lid 4 by the door 6.
  • The enclosure 31 is comprised of an upper edge-side straightening vane 31 e and two lateral edge-side straightening vanes 31 f and 31 g and has a rectangular solid shape whose one surface facing the wall 11 is an open surface. The lateral length (length in the direction of a side of the first aperture 10 extending in the horizontal direction thereof, i.e., the width) of a space formed in the enclosure 31 is set so as to allow the enclosure to accommodate the door 6 and a later-described curtain nozzle 12. In addition, the longitudinal length (length in the direction of a side of the first aperture 10 extending in the vertical direction thereof) of the space is defined as the minimum length which allows the enclosure to accommodate the door 6 even if the door 6 is placed in either the retreat position or the closure position of the first aperture 10, and also accommodate the later-described purge nozzles 21 located in a portion outside the side edges of the first aperture 10. Note that a reinforcing plate material may be located between the two lateral edge-side straightening vanes 31 f and 31 g to couple these vanes together.
  • As a thickness (length in the operating direction of the movable plate 54, i.e., a depth), the space has a length which prevents the flat surface 6 b on the opposite of a surface of the door 6 on the first aperture 10 side and the enclosure 31 from interfering with each other, and allows the flat surface 6 b to substantially close the second aperture 31 a when the door 6 rotates around the fulcrum 61 to take the posture of retreat and stops at the time of opening the first aperture 10. The enclosure 31 is located in a position best suited for the enclosure to accommodate the purge nozzles 21, the curtain nozzle 12 and the door 6 and, along with the wall 11, forms a second minute space 30 having a substantially rectangular solid shape.
  • A rectangular second aperture 31 a is formed in a surface of the enclosure 31 opposed to the first aperture 10. The second aperture 31 a is arranged oppositely to the first aperture 10. The rectangular shape of the aperture preferably has such a minimum size as to prevent the enclosure 31 from interfering with the operation of an unillustrated transport mechanism arranged in the minute space to take each wafer 1 in and out of the pod 2. This way of enclosure configuration is intended to bring the second minute space 30 within the enclosure 31 as close to the enclosed space as possible, and obtain a state in which the interiors of the space 30 and minute space 52 are substantially isolated from each other. The side of the enclosure 31 facing in the retreat direction of the door 6 is open. A purge gas is supplied vertically downward from the later-described purge nozzles 21 within the enclosure 31. Since a bottom face 31 b is open, a state of a so-called downflow being constantly formed can be obtained also within the enclosure 31.
  • The curtain nozzle 12 is located in the uppermost portion of a space (the upper side of the upper edge of the first aperture) in the interior of the enclosure 31 immediately before the first aperture 10. The curtain nozzle 12 is arranged in order to form a downflow inside the second minute space 30 and a gas curtain immediately before the first aperture 10. In the present embodiment, the curtain nozzle 12 is located as close as possible to an upper end face 31 d (face opposed to the abovementioned bottom face 31 b) of the enclosure 31. The curtain nozzle has a rectangular solid shape having upper and lower faces one size smaller than the upper end face 31 d. A plurality of nozzle apertures 12 b is formed in a lower face 12 a of the curtain nozzle 12.
  • The purge nozzles 21 for supplying a purge gas to purge the interior of the pod 2 are also located inside the enclosure 31. Each purge nozzle 21 includes a tubular purge nozzle main unit 21 a extending in one direction and is connected to an unillustrated purge gas supply system. The purge nozzle main units 21 a are disposed in a pair and adjacently to outer sides of the two lateral edges of the aperture 10 on a side of the load port aperture 10 different from the side of the mounting stage on which the pod 2 is placed, so as to extend parallel to the lateral edges.
  • FIG. 3 illustrates a schematic configuration when the purge nozzle main units 21 a, the pod 2, the wafers 1 and the enclosure 31 are viewed from thereabove. In each purge nozzle main unit 21 a, a plurality of purge nozzle apertures 21 b is preferably disposed at equal intervals in the extending direction thereof, so as to agree with an interval at which the wafers 1 are housed in the pod 2 and with a spacing between respective wafers 1. In addition, the purge nozzle apertures 21 b are formed so as to be directed at the central part of each wafer 1. That is, the direction of gas supply from each purge nozzle is preferably parallel to a plane extending perpendicularly to the direction of gas supply from the curtain nozzle and toward a point at an equal distance from the two purge nozzles within the plane.
  • The purge gas can be reliably supplied into the pod 2 by setting the direction of gas supply from the purge nozzles perpendicularly to the flow direction of a curtain gas. Originally, the purge gas is most effectively ejected so as to head to a wafer surface. For such a reason that the wafers 1 are narrowly spaced within the pod 2, however, a gas supply is made parallel to the wafer surface. Note that in practice, the purge nozzles 21 and the abovementioned curtain nozzle 12 are connected to an unillustrated gas supply system. For ease of understanding the configuration of the present invention, however, the drawing shows these nozzles without including the gas supply system. Also note that this gas supply system is a common system comprised of a gas source, a regulator and the like, and therefore, will not be discussed here.
  • In the present embodiment, the nozzle apertures 12 b are formed over almost the entire surface of the bottom face 12 a of the curtain nozzle 12. Accordingly, a so-called downflow based on a curtain gas supplied from the curtain nozzle 12 is constantly formed in the space between the first aperture 10 and the second aperture 31 a within the enclosure 31 when the door 6 is in the retreat position. In a state of being in communication with the interior of the pod 2, the second minute space 30 is communicated with the minute space 52 by the second aperture 31 a, through-holes in the bottom face 31 b of the enclosure, and the like. That is, the bottom face 31 b of the enclosure serves as a gas outlet port and an outflow path of the curtain gas. In the present invention, the gas outlet port is located in a position opposite to the flow direction of the curtain gas and perpendicularly to the gas flow. By locating the outflow path of the curtain gas in the bottom face 31 b of the enclosure, it is possible to reliably extend the downflow up to the lower portion of the second minute space 30 in a stable state of flow.
  • In addition, the curtain gas is easier to control in terms of so-called contaminants, such as particles, than a gas (atmospheric air) supplied into the minute space 52 through a later-described fan filter unit. Accordingly, it is possible to more effectively prevent the inflow of contaminants from the minute space 52 side into the pod 2, compared with a conventional load port, by locating the curtain gas-based downflow in a position immediately before the first aperture 10.
  • Here, a so-called downflow 63 a based on clean air is formed in the minute space 52 by a fan filter unit (FFU) 63 located in the upper portion of the space, in order to maintain cleanness in the interior of the space at a high level. That is, the minute space 52 is placed under particle control and used as a space where the transport mechanism is arranged. An unillustrated gas outflow path is provided in the lower portion of the minute space 52. Pressure inside the minute space 52 is kept slightly higher than pressure in a space outside the minute space, however, by adjusting the amount of air blow of the fan filter unit 63. By adjusting the amount of curtain gas flowing out of the gas outflow path communicated with the minute space 52 and the amounts of curtain gas and purge gas supplied from the curtain nozzle 12 and the purge nozzles 21, it is possible to easily create an environment in which internal pressure lowers in the order of the second minute space 30, the minute space 52 and the outer space.
  • Note that in practice, pressure differences among these spaces are marginal. If, for example, the second minute space 30 is arranged in a specific exhaust path and gases are discharged by the exhaust path, it is in fact difficult to provide such pressure differences. In the present invention, a path communicated with the minute space 52 in the lower portion of the space is used as a main path of gas outflow from the second minute space 30 serving as a gas outlet port by arranging a communicating part in the downstream of a linear flow of purge gas. Thus, the exhaust resistance of the path is adjusted to an appropriate value to make it easy to create the abovementioned pressure differences.
  • In the present embodiment, the second aperture 31 a is arranged so that the direction in which the second aperture 31 a is open is parallel to the direction of the downflow 63 a from the fan filter unit 63. In addition, the curtain nozzle 12 is arranged so that the flow direction of purge gas supplied from the curtain nozzle 12 is also parallel to the direction in which the second aperture 31 a is open. Since the flow of the purge gas and the flow of the downflow 63 a are parallel to each other and a slight flow velocity difference is kept therebetween from the viewpoint of maintaining a fine pressure difference, the action of a so-called venturi effect is marginal. Accordingly, atmospheric air drawn from the minute space 52 into the second minute space 30 by the venturi effect is kept to a small amount. On the other hand, gases present within the pod 2 are inherently stationary, and therefore, largely differ in flow velocity from the curtain gas. Consequently, there can be expected an effect of drawing out the gases inside the pod 2 to the second minute space 30 side by the venturi effect. The above-described effect, along with the supply of purge gas, enables purge operation within the pod 2 to be performed more efficiently.
  • It is conceivable that gases used during processing and attached to wafer surfaces desorb therefrom to contaminate the minute space 52 when, for example, processed wafers are housed in the pod and taken in and out of the pod. In the present invention, the desorbed gases are driven out from the vicinity of the wafer surfaces by the purge gas and carried by the curtain gas from the second minute space 30 to the minute space 52 through the abovementioned gas outlet port. The gases can be carried out of the minute space 52 through an unillustrated exhaust part (formed in the lower portion or bottom face of the minute space 52) for discharging the downflow 63a from within the minute space 52 to the outer space. Accordingly, the gases deriving from the wafers are driven out into the outer space through the second minute space which is narrow and high in downflow velocity, rather than from a minute space which is wide and low in downflow velocity in a conventional system configuration, while minimizing the time taken for the gases to go through the minute space. That is, the interior of the pod 2 containing the processed wafers can be purged more efficiently by allowing the curtain gas and the purge gas flowing in different directions to be simultaneously present in the pod.
  • When a gas is supplied toward a specific space by a commonly-used nozzle or the like, gases in the vicinity of the nozzle get involved in the gas by the earlier-mentioned venturi effect. As a result, the purity of the gas supplied degrades from the time immediately after the gas is released from the nozzle or the like. In the present invention, a wall constituting the enclosure 31 is located at the back of both the curtain nozzle 12 and the purge nozzles 21. Consequently, atmospheric air is unlikely to be supplied from outside the enclosure 31 to the vicinity of these nozzles. Thus, gases, other than a predetermined gas, present in the vicinity of the nozzles can be reduced as much as possible by performing gas release operation for a certain period of time. That is, it is also possible to supply gases kept at a high level of purity from the nozzles.
  • It is also an object of the present invention to prevent a rise in the partial pressure of an oxidizing gas within the pod 2 in a so-called standby state in which the lid is fixed to the pod 2. In the present embodiment, a high-flow rate supply of an inert gas from each purge nozzle 21 is primarily applied in so-called purge operation on the interior of a commonly-used pod 2. The flow rate is, for example, 300 L/min. With this flow rate, it is possible to decrease the partial pressure of the oxidizing gas within the pod 2 to or below a predetermined value in a short period of time. In the standby state, a rise in the partial pressure of the oxidizing gas is attributable to inherently-unacceptable minor leakage or the like. There is therefore no need for a supply of an inert gas at a high flow rate. In the present embodiment, the inert gas is supplied through the gas supply valve 53 a and the gas supply port 2 d at a low flow rate of, for example, 1 to 60 L/min, which is a total flow rate of the inert gas from all of the gas supply valves 53 a and the gas supply ports 2 d and at which it is less likely to stir up dust and the like having potentially problematic sizes from the valve or the port. Note that if, for example, the flow rate of a gas supplied from each purge nozzle is high, the abovementioned low flow rate may alternatively be set lower than this flow rate. Regarding the above flow rate, a flow rate of the inert gas from one set of the gas supply valve 53 a and the gas supply port 2 d is preferably set to 1 to 20 L/min. In a case of setting the gas flow rate from one set to 1 to 20 L/min, the dust and the like stirred up by the gas flow in the area on which the gas supply valve 53 a and the gas supply port 2 d, is suppressed or prevented.
  • With the flow rate mentioned above, it is possible to prevent a rise in the partial pressure of an oxidizing gas by applying such a low flow velocity at which dust can be prevented from being stirred up, even if the diameter of the gas supply pipe 57 is small. More specifically, since dust or the like having such sizes as to possibly cause problems in wiring lines to be formed on a wafer will become problematic, control is performed so as to make a nitrogen supply at such a low flow rate and pressure as to be able to prevent dust or the like having these sizes from being stirred up from the gas supply port 2 d or the like. In the present embodiment, the abovementioned flow rate is selected on the basis of the above-described conditions and the minimum amount of gas supplied to maintain the interior of the pod 2 at a constant positive pressure (pressure higher than the pressure of the outer space) during a standby time.
  • Note that in the present embodiment, any significant effects cannot be expected from inert gas supply from the abovementioned path in a state of the lid 4 being removed. Instead, inert gas supply from the purge nozzles 21 is suitable. Accordingly, the present embodiment is intended to make an inert gas supply at suitable points in time by unillustrated control means. More specifically, the present embodiment is adapted so that the closure of the aperture 2 b with the lid 4 is detected by the earlier-mentioned lid opening/closing detection means and then, in response, the control means allows the inert gas supply system to start inert gas supply. In the present embodiment, a mode of using only one combination of constituent parts comprised of the gas supply valve 53 a is shown by way of example. As will be described later, however, the number of combinations may be increased according to the inner volume of the pod 2 or the required partial pressure of an oxidizing gas. Alternatively, it is also possible to configure the system of the present embodiment such that an exhaust port for discharging gases within the pod 2 is newly added to further reduce the partial pressure of the oxidizing gas also during a standby time.
  • According to the present invention, it is possible to prevent a rise in the partial pressure of an oxidizing gas by continuing gas supply from the port even under a sealed condition in which a gas within the pod leaks even in a state of the lid thereof being closed, and the ingress of external gases is likely to occur. For example, a case is conceivable in which if the processing time of a wafer alone is long, the lid is closed as appropriate to wait for the end of one cycle of processing in a standby state. Conventionally, the partial pressure of the oxidizing gas within the pod rises as the standby time is prolonged, and therefore, wafer surface oxidation may progress. According to the present invention, however, the partial pressure of the oxidizing gas is constantly kept to or below a predetermined value even if the standby state is prolonged. Thus, there can be obtained an effect of maintaining the quality of all of wafers within the pod.
  • By arranging a quasi-second minute space where not only particles but also the partial pressure of the oxidizing gas is controlled between a minute space where particles are controlled but the partial pressure of the oxidizing gas is not controlled and the interior of the pod, it is possible to more significantly suppress the amount of oxidizing gas diffusing from the minute space to the pod, compared with a conventional system configuration. In addition, the system is configured such that the second minute space and the minute space are communicated with each other by a gas outlet port and gases within the second minute space flow out into the minute space according to the pressure difference between these spaces. Yet additionally, an inert gas is supplied from a wall surface of the pod thereinto. It is therefore possible to easily generate atmospheric pressure differences among the second minute space, the minute space, and the vicinity of the minute space with a simple system configuration. Consequently, it is possible to effectively prevent the diffusion of an oxidizing gas from the minute space into the pod.
  • In addition, a downflow based on a purge gas is created within the second minute space and a so-called gas curtain is formed by the downflow. Consequently, it is possible to effectively prevent the diffusion of atmospheric air, the scatter of particles, and the like from the minute space toward the pod. Yet additionally, by combining the abovementioned effect and the above-described effect of generating pressure differences, it is possible to obtain the same or higher effect of maintaining the low partial pressure of a oxidizing gas using a small amount of purge gas, compared with a case in which a large amount of purge gas is required to prevent the ingress of an oxidizing gas into the pod simply by supplying the purge gas into the pod or with a conventional system configuration in which a gas curtain is formed by supplying a large amount of purge gas from one direction and suctioning and discharging the gas from another direction.
  • Note here that it is known that when a gas is ejected from a nozzle, the gas involves other gases present in the vicinity of a nozzle aperture to turn into a mixed gas, thus forming a gas flow. That is, as the result of the gas involving other gases present in the vicinity of the nozzle aperture when a gas curtain is formed, the concentration of a purge gas, such as an inert gas, forming the gas curtain decreases. Thus, there is the possibility of an oxidizing gas being supplied from the gas curtain into the pod. According to the present invention, the small-volume second minute space substantially closed by the enclosure and the door is filled to some degree with a purge gas using the gas curtain, and then the purge gas is supplied from the purge nozzles different from the curtain nozzle. Accordingly, even if the purge gas supplied from the purge nozzles involves gases around the purge nozzles, it only means that the purge gas involves gases originally low in the partial pressure of an oxidizing gas. Thus, it is possible to prevent a degradation in the purity of the purge gas.
  • In addition, the periphery of the curtain nozzle is also surrounded by the enclosure and can therefore be also easily filled with a purge gas having purity above a certain level. The same is true for the purge nozzles. The periphery of each purge nozzle is surrounded by the enclosure and can therefore be also easily filled with a purge gas having purity above a certain level. By the effects described above, it is possible to also obtain an effect of keeping the partial pressure of an oxidizing gas contained in gases introduced to the periphery of the pod lower than before.
  • Next, a description will be made of the operation of the above-described system configuration when the wafer 1 is actually taken in and out of the pod 2. The door 6 substantially closes the first aperture 10 at the time the pod 2 is placed on the mounting stage 53. Note that in the present embodiment, the door 6 is sized so as to form such a gap therearound as to cause the minute space 52 and the outer space to be communicated with each other when the door is in a position to close the first aperture 10. Accordingly, in the present embodiment, the door 6 is only capable of approximately closing the first aperture 10. After the placement of the pod 2, the movable plate 54 moves toward the first aperture 10 and stops at a position to cause the lid 4 to abut on the door 6. The door 6 holds the lid 4 with an unillustrated engaging mechanism. Note here that from the time before the pod 2 is placed, downflows are constantly formed within the minute space 52 by means of the fan filter unit 63 and within the second minute space 30 by gas supply from the curtain nozzle 12.
  • As described above, the flat portion 6 b located at the back of the door 6 is arranged at a tilt with respect to the flow of a gas forming a gas curtain, so as to come closer to the second aperture 31 a as the flat portion moves away from the curtain nozzle 12. In addition, the lower end of the flat portion 6 b is positioned below the lower edge thereof constituting the second aperture 31 a. The internal pressure of the second minute space 30 divided off by the enclosure 31 is made higher than pressure inside the minute space 52 by gas supply from the gas curtain nozzle 12. The inflow of particles and the like from the minute space 52 into the second minute space 30 is more effectively prevented by applying, in addition to the pressure difference, a system configuration in which the inclined surface of the flat portion 6 b changes the direction of the gas curtain and flows part thereof into the minute space 52.
  • Subsequently, the door opening/closing mechanism 60 rotates the door arm 6 a around the fulcrum 61, causes the door 6 to take the posture of retreat illustrated in FIG. 4A, and makes the pod 2 partially open to the second minute space 30. Note that FIGS. 4A and 4B to be discussed later illustrate states of the enclosure 31 when the periphery of the enclosure 31 is viewed from the lateral side thereof in the same way as in FIG. 2A. From this state of the system, purge gas supply from the purge nozzle is initiated. The door opening/closing mechanism 60 retreats the door 6 down to the retreat position which is the lowermost end within the enclosure 31, while allowing the door 6 to maintain this posture of retreat. FIG. 4B illustrates a state of the door 6 being placed in the retreat position. In this state, the aperture 2 b of the pod 2 is made open, thereby enabling operation by an unillustrated transport mechanism arranged in the minute space 52 to transfer the wafer 1 into the pod 2 through the second aperture 31 a.
  • FIG. 4C illustrates a schematic configuration in which the first aperture 10 is viewed from the minute space 52 side in the same way as in FIG. 2B. A gas, such as a purge gas, is supplied from the curtain nozzle 12, so as to form a downflow parallel to the wall 11. In addition, the purge gas is supplied from each of a pair of the purge nozzles 21, so that the flow of each purge gas heads for the central part of the wafer 1 housed in the pod 2. Under the above-described condition, the wafer 1 is transferred. Purge operation on the interior of the pod 2 is performed continuously during the transfer operation to keep low the partial pressure of an oxidizing gas within the pod. After carry-in operation on the wafer 1 to be housed in the pod 2 is completed, the closing operation of the lid 4 is performed as described below.
  • In the closing operation, the door opening/closing mechanism 60 raises and brings back the door 6 up to the position illustrated in FIG. 4A where the door 6 stopped rotating to take the posture of retreat. Under this condition, the door opening/closing mechanism 60 stops operation once and maintains the door 6 in that posture before its rotation. At that time, the flat surface 6 b located at the back of the door 6 comes into substantially close contact with the periphery of the second aperture 31 a of the enclosure 31, thereby increasing the degree of closure of the second minute space 30. In addition, the lid 4 held on the door 6 is positioned at a certain flow angle with the gas curtain, thereby changing the direction of gas flow from downward from the enclosure toward the interior of the pod.
  • By an increase in the degree of closure of the enclosure 31, it is possible to easily raise the partial pressure of a purge gas present in a space including the second minute space 30 and the inner space of the pod 2. In addition, purge efficiency within the pod 2 is further enhanced since the curtain gas can be directly used to purge the interior of the pod 2. After the interior of the pod 2 is fully purged and the amount of oxidizing gas present in the abovementioned space is sufficiently reduced by maintaining the condition shown in FIG. 4A for a predetermined period of time, the door opening/closing mechanism 60 rotates the door 6 and closes the aperture 2 b of the pod main body 2 a with the lid 4. By the operations described above, it is possible to enclose the wafer 1 in the pod 2 at such a low concentration of an oxidizing gas as is not available with a conventional configuration.
  • Subsequently, the lid opening/closing detection means detects the closure of the aperture 2 b with the lid 4, and notifies this to the control means. In response to the notification of the detection of closure, the control means instructs the inert gas supply system to supply an inert gas. The inert gas supply system begins supplying an inert gas into the pod 2 through the gas supply valve 53 a and the gas supply port 2 d at a predetermined flow rate or flow velocity. The control means also instructs a mechanism for supplying an inert gas to the purge nozzle 21 to lower the flow rate or stop inert gas supply. This operation prevents or suppresses unnecessary use of the inert gas. By performing the operations described above, it is possible to satisfy both a decrease in the partial pressure of an oxidizing gas inside the pod 2 and the maintenance of that condition in an atmospheric state through the use of a necessary and sufficient amount of inert gas.
  • Note that in the above-described operations, the door 6 is kept being retreated from the start to the end of carrying in and out the wafers, while the wafers are being taken in and out. Here, if an attempt is made to promptly and effectively purge the interior of the pod 2, a large amount of purge gas needs to be supplied into the space being purged to raise the pressure thereof and rapidly drive out gases previously present therein. It is difficult, however, to extremely raise the internal pressure of the second minute space 30 if the second aperture 31 a is in an open state as in the above-described operation. In addition, if the open time is long, the partial pressure of an oxidizing gas within the pod 2 may conceivably increase gradually due to the diffusion of atmospheric air from the minute space 52. In such a case, it is desirable to purge the pod 2 by raising the door 6 from the retreat position to the position shown in FIG. 4A where the second aperture 31 a is substantially closed, and placing the interiors of the second minute space 30 and the pod 2 in a substantially airtight state each time one wafer 1 is taken in and out. Consequently, it is possible to effectively prevent a rise in the partial pressure of the oxidizing gas.
  • Note that in the embodiment described above, the curtain nozzle 12 has a rectangular solid shape and gas ejection holes are arranged on the entire lower surface of the nozzle. It is desirable, however, to change the shape, the layout and the number of ejection holes as appropriate, according to the flow rate of a gas to be supplied, the volume of the second minute space 30, and the like. It is also preferable to change the shape, the layout and the like of the gas-ejecting apertures 21 b of the purge nozzles 21 as appropriate. Also note that in the above-described embodiment, the door 6 substantially closes the first aperture 10. Alternatively, the door 6 may be configured to completely close the first aperture 10. Also note that in the above-described embodiment, the bottom face 31 b of the enclosure is made open to serve as a gas outlet port arranged oppositely to the flow direction of a curtain gas. Alternatively, the bottom face 31 b may have, for example, a mesh structure, a structure provided with certain slits, a structure comprised of punched, perforated metal, or the like which does not disturb the formation of a downflow and the operation of the door 6 and exhibits a certain degree of exhaust resistance.
  • From the viewpoint of preventing the generation of particles and the like, the amount of rotation of the door 6 is determined so that walls around the second aperture 31 a of the enclosure 31 and the flat surface 6 b come close to but not into contact with each other. More preferably, however, the space between the flat surface 6 b and the enclosure 31 is sealed up when the interiors of both the second minute space 30 and the pod 2 are purged at the same time. In this case, the door 6 may have a two-step range of rotation to differentiate the position of the door 6 between purge operation and retreat, so that these constituent components temporarily come into close contact with each other only at the time of purge operation. Alternatively, a sealing member which expands or shrinks due to fluid introduction or discharge, for example, may be arranged in the outer circumference of the flat surface 6 b. In this case, the sealing member may be structured so that the above-described degree of close contact can be achieved by expanding and bringing the member into close contact with the enclosure 31 only at the time of purge operation, and the contact with the enclosure 31 can be canceled by shrinking the sealing member.
  • Next, a description will be made of other embodiments of the present invention. In the above-described embodiment, a system configuration has been shown by way of example in which a gas supply is made from the gas supply valve 53 a located in the mounting stage 53 to the pod 2 through the supply port 2 d. In the present embodiment, not only a gas is supplied to the pod 2 but also the gas is discharged from within the pod 2 in a state of being high in internal pressure due to the gas supply, thereby forming a flow of clean gas within the pod 2. Thus, the partial pressure of an oxidizing gas is lowered more effectively. FIG. 8 is one example of the present embodiment and illustrates gas supply valves 53 a and a gas exhaust valve 53 b arranged in the upper surface of a mounting stage 53. Note that in FIG. 8, a first aperture 10 is arranged above the figure. In addition, these valves respectively have structures consistent with the structures illustrated by way of example in FIG. 7, and ports adapted respectively to use with these valves are also arranged in the bottom face of the pod 2. In the present embodiment, an example is shown in which these valves are comprised of three gas supply valves 53 a and one gas exhaust valve 53 b.
  • In the present embodiment, gases are discharged from an unillustrated gas exhaust system to the gas exhaust valve 53 b through a gas exhaust pipe arranged in the same way as the gas supply pipe 57. It is also possible to exclude the gas exhaust system and discharge gases by taking advantage of pressure within the pod 2. In addition, the control means arranged in the earlier embodiment may operate the gas exhaust valve 53 b according to the operation of the gas supply valves 53 a. In another aspect of the present embodiment, the gas exhaust valve 53 b may be a so-called differential pressure valve or the like, and the valve goes into an open state at the moment the internal pressure of the pod 2 exceeds a predetermined pressure. In order to prevent dust or the like from getting inside the gas supply pipe through the gas supply valves 53 a, filters or the like may be arranged in the gas supply valves 53 a. By arranging filters or the like in gas supply lines as described above, it is possible to avoid bringing dust into the pod 2 at the time of supplying an inert gas from the lines into the pod.
  • Note that various modifications can be made according to, for example, a mode in which only some of these valves are used, a mode in which the number of valves is varied between supply and exhaust purposes, the inner volume of the pod 2, or the required partial pressure of an oxidizing gas. For example, it is possible to adopt a mode in which one valve is used as a gas supply valve 53 a, another valve is used as a gas exhaust valve 53 b, and other two valves are not used. It is also possible to change the total number of valves and the layout thereof. For example, a mode is conceivable in which the number of valves itself is increased to eight or the gas supply valve 53 a is positioned in the deepest part of the pod 2 and located in immediate proximity to a sidewall thereof. Yet additionally, in these embodiments, valves and ports are located only in the bottom face of the pod 2 in consideration of compatibility with an existing load port apparatus. The same effect can be obtained, however, even if some or all of the valves and ports are arranged on the lateral side, the upper surface, or the lid side of the pod 2.
  • In the above-described embodiment, a case is illustrated by way of example in which the amount of inert gas supplied from each purge nozzle 21 is 300 L/min, and the total amount of the inert gas supplied of all of the gas supply valves 53 a is 1 to 60 L/min and amount of inert gas supplied from each gas supply valve 53 a is 1 to 20 L/min. In practice, however, an actual amount of the inert gas supplied from each purge nozzle 21 is controlled within a range from 60 to 300 L/min, according to a required inner volume of the pod, a required partial pressure of an oxidizing gas, and the like. Accordingly, the amount supplied is in practice controlled within a range from 1 to 60 L/min according to these conditions and to variations in the number of gas supply valves 53 a, the layout thereof, or the like as in the case of the present embodiment. Taking into consideration the time required to decrease the partial pressure of an oxidizing gas to or below a desired value, the amount of inert gas supplied through each gas supply valve 53 a should preferably be as large as possible. Taking into consideration the stirring up of dust and the like due to gas supply, however, the amount should preferably be as small as possible. In consideration of the characteristics of the above-described respective inert gas supply systems, the amount of inert gas supplied from each gas supply valve 53 a is most preferably controlled within a range from 1 to 45 L/min.
  • Note that in above described embodiment, is described a case where both the inert gas supplied from the purge nozzle and the inert gas supplied from the gas supply valve and the gas supply port are used. However, the present invention is not limited by the above described aspect. It is preferable that the inert gas is not supplied from the purge nozzle but the inert gas is only supplied from the gas supply valve and the gas supply port. In such aspect, an effect of suppressing the dust and the like stirred up by the gas flow can be obtained by setting a flow rate of the inert gas from one unit of the gas supply valve and the gas supply port to 1 to 20 L/min, and setting the total flow rate of the inert gas from the gas supply valves and the gas supply ports to 1 to 60 L/min. Further, by satisfying the both requirements of each inert gas flow of 1 to 20 L/min and total inert gas flow to 1 to 60 L/min, the stirring the dust and the like can be preferably suppressed. Note that although the combination of the purge nozzle and the gas supply valve and the gas supply port improve the working efficiency of purge operation, in a case of considering the prevention of stirring up the dust and the like the inert gas supply from the gas supply valve and the gas supply port is mainly used o as to shorten the time required for the purge operation and to suppress the influence of the dust and the like effectively.
  • EXAMPLE EMBODIMENT
  • Next, a description will be made of a FIMS system which is an actual lid opening/closing system and for which the present invention is carried out, and a semiconductor wafer processing apparatus using the system. FIG. 5 is a schematic view illustrating a schematic configuration of a semiconductor wafer processing apparatus 50 compliant to a so-called mini-environment method. The semiconductor wafer processing apparatus 50 is comprised mainly of a load port unit (a FIMS system and a lid opening/closing apparatus) 51, a transfer chamber (minute space) 52, and a processing chamber 59. Interfaces among these respective component parts are defined by a load port-side partition and cover 58 a and a processing chamber-side partition and cover 58 b. In the transfer chamber 52 of the semiconductor wafer processing apparatus 50, an aerial flow (downflow) is generated from above to below the transfer chamber 52 by a fan filter unit 63 arranged in the upper portion of the transfer chamber 52, in order to drive out dust and maintain a high degree of cleanness. In addition, a downflow exhaust path is provided in the bottom face of the transfer chamber 52. The above-described apparatus configuration causes dust to be constantly driven out downward.
  • A pod 2 which is a container for housing silicon wafers or the like (hereinafter simply referred to as wafers) is placed on a mounting stage 53 of the load port unit 51. As described earlier, the interior of the transfer chamber 52 is kept at a high degree of cleanness in order to process wafers 1. In addition, in the transport mechanism, a robot arm 55, which can actually hold a wafer, is arranged within the transfer chamber 52. By this robot arm 55, each wafer is transferred between the interiors of the pod 2 and the processing chamber 59. In general, various types of mechanisms used to perform treatments, such as thin-film formation and thin-film processing, on a wafer surface or the like are contained in the processing chamber 59. These constituent parts are not directly relevant to the present invention, however, and therefore will not be discussed here.
  • As described above, the pod 2 is comprised of a box-shaped main body 2 a having a space for containing the wafer 1 which is an object to be processed and including an aperture in one of the faces of the pod, and a lid 4 for hermetically closing the aperture. A rack including a plurality of shelves to stack wafers 1 in one direction is arranged within the main body 2 a. Wafers 1 to be placed on these shelves are housed in the pod 2 while being regularly spaced. Note that in the example shown here, the direction in which the wafers 1 are stacked is defined as the vertical direction thereof. The aperture 10 and the abovementioned enclosure 31 are arranged on the load port unit 51 side of the transfer chamber 52. The aperture 10 is located in a position to face the aperture of the pod 2 when the pod 2 is placed on the load port unit 51 so as to come close to the aperture 10. Note that the main configuration of the enclosure 31, the door 6 and the like according to the present invention will not be discussed and illustrated here for reasons that they have already described in the foregoing embodiments and from the viewpoint of making the drawings in question easy to understand.
  • FIGS. 6A and 6B respectively illustrate an enlarged cross-sectional side view of the door 6 and the door opening/closing mechanism 60 of the apparatus and a front view when these constituent parts are viewed from the transfer chamber 52 side. A fixing member 46 is attached to the door 6, and the door 6 is pivotally coupled with one end of the door arm 6 a through the fixing member 46. The other end of the door arm 6 a is supported to the leading end of a rod 37 which is part of an air-driven cylinder, through an axis 40, so as to be rotatable around the axis 40.
  • A through-hole is provided between the one and the other ends of the door arm 42. An unillustrated pin penetrates through the through-hole and a hole of the fixing member 39 fixed to a supporting member 60 of a movable unit 56 for raising/lowering constituent parts, such as the door arm 42, for opening/closing the door, thereby forming a fulcrum 61. Accordingly, the door arm 42 can rotate around the fulcrum 61 in response to the cylinder-driven extension and contraction of the rod 37. The fulcrum 61 of the door arm 42 is fixed to the supporting member 60 provided in the movable unit 56 capable of up-and-down movement.
  • When each wafer 1 is processed using these constituent parts, the pod 2 is first placed on the mounting stage 53, so as to come close to the aperture 10 of the transfer chamber, and the lid 4 is held by the door 6. Note that an unillustrated engaging mechanism and an unillustrated mechanism to be engaged are arranged on surfaces of the door 6 and the lid 4, respectively. These mechanisms operate with the surfaces of the lid 4 and the door 6 abutting on each other, thereby allowing the door 6 to close the lid 4. When the rod of the cylinder is contracted under this condition, the door arm 42 rotates around the fulcrum 61, so that the door 6 moves away from the first aperture 10. This operation causes the door 6 to rotate along with the lid 4 and remove the lid 4 from the pod 2. Thereafter, the movable unit 56 is lowered to carry the lid 4 to a predetermined retreat position. This carrying operation has already been described in the foregoing embodiments, and therefore, will not be discussed here.
  • Note that although the present example embodiment is described with FOUPs and FIMS systems as targets, applications of the present invention are not limited to these. As far as a front open type container for containing a plurality of objects to be held and a system for opening/closing the lid of the container to take the objects to be held in and out of the container are concerned, it is possible to apply a lid opening/closing apparatus according to the present invention to the container and the system and keep low the partial pressure of an oxidizing atmosphere within the container. In cases where a specific gas having desired properties, rather than an inert gas, is used as a gas to be filled in the container, it is also possible to use the lid opening/closing apparatus according to the present invention to keep the partial pressure of the specific gas within the container at a high level.
  • According to the present invention, there are obtained an effect of shielding a space with an enclosure and an effect of preventing the ingress of external gases from a gas curtain or the like due to purge gas supply. In addition, by supplying a purge gas toward a wafer separately from the gas curtain, it is possible to effectively suppress a rise in the partial pressure of an oxidizing gas among gases within a pod. Yet additionally, the present invention can be carried out simply by adding an enclosure, a curtain nozzle, a purge nozzle and the like to an existing FIMS system. Consequently, the present invention can be inexpensively, simply and conveniently applied to any standardized systems.
  • While the present invention has been described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. The scope of the following claims is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures and functions.

Claims (10)

    What is claimed is:
  1. 1. A lid opening/closing system including a container, the container being provided with: a substantially box-shaped main body capable of containing an object to be housed and having an aperture in one face of the container main body; a lid separable from the container main body and adapted to cover the aperture to form an enclosed space along with the container main body; and at least one supply port provided on a wall surface of the container main body and capable of supplying a gas from the outside, wherein the object to be housed is allowed to be taken in and out of the container by removing the lid from the container to open the aperture, the system comprising:
    a mounting stage on which the container is placed;
    a minute space located adjacent to the mounting stage to contain a mechanism for transporting the object to be housed with particles controlled;
    a substantially rectangular first aperture formed in a wall located adjacent to the mounting stage to define part of the minute space, the first aperture being provided in a position where the first aperture is able to face the aperture of the container placed on the mounting stage;
    a door capable of holding the lid and substantially closing the first aperture, and capable of causing the aperture and the first aperture to be communicated with each other by holding the lid and opening the first aperture;
    a supply valve for supplying a gas into the container in conjunction with the supply port; and
    a gas supply system for supplying a predetermined gas through the supply port and the supply valve at a total flow rate of 1 to 60 L/min with the container placed on the mounting stage.
  2. 2. The lid opening/closing system according to claim 1, further comprising: opening/closing detection means for detecting the opening/closing of the aperture by the door using the lid; and control means for starting the supply of the predetermined gas to the gas supply system in response to the closure of the aperture detected by the opening/closing detection means.
  3. 3. The lid opening/closing system according to claim 2, further comprising a purge nozzle capable of supplying the predetermined gas to the container through the aperture of the container, wherein the control means performs the start and stop of the supply of the predetermined gas by the purge nozzle in response to the detection of the opening/closing of the lid by the detection means.
  4. 4. The lid opening/closing system according to claim 1, wherein the container further includes at least one discharge port provided on a wall surface of the container main body and capable of discharging gases to the outside, and the system further comprises a discharge valve for discharging gases from within the container in conjunction with the discharge port.
  5. 5. The lid opening/closing system according to claim 1, further comprising:
    an enclosure arranged in the minute space in series with the first aperture to cover the moving space of the door and constitute a second minute space, the enclosure having a second aperture through which the first aperture and the minute space communicate with each other and the mechanism for transporting the object to be housed is allowed to pass along with the object to be housed; and
    a curtain nozzle located in a portion above the upper edge of the first aperture inside the enclosure and capable of supplying the predetermined gas along a direction from the upper edge toward the lower edge of the first aperture,
    wherein the enclosure includes a gas outlet port from which the gas is allowed to flow out into the minute space along a direction in which the gas flows.
  6. 6. A lid opening/closing system including a container, the container being provided with: a substantially box-shaped main body capable of containing an object to be housed and having an aperture in one face of the container main body; a lid separable from the container main body and adapted to cover the aperture to form an enclosed space along with the container main body; and a plurality of supply ports provided on a wall surface of the container main body and capable of supplying a gas from the outside, wherein the object to be housed is allowed to be taken in and out of the container by removing the lid from the container to open the aperture, the system comprising:
    a mounting stage on which the container is placed;
    a minute space located adjacent to the mounting stage to contain a mechanism for transporting the object to be housed with particles controlled;
    a substantially rectangular first aperture formed in a wall located adjacent to the mounting stage to define part of the minute space, the first aperture being provided in a position where the first aperture is able to face the aperture of the container placed on the mounting stage;
    a door capable of holding the lid and substantially closing the first aperture, and capable of causing the aperture and the first aperture to be communicated with each other by holding the lid and opening the first aperture;
    a plurality of supply valves for each supplying a gas into the container in conjunction with each of the plurality of supply ports; and
    a gas supply system for supplying a predetermined gas through one unit of the supply port and the supply valve at a flow rate of 1 to 20 L/min with the container placed on the mounting stage.
  7. 7. The lid opening/closing system according to claim 6, further comprising: opening/closing detection means for detecting the opening/closing of the aperture by the door using the lid; and control means for starting the supply of the predetermined gas to the gas supply system in response to the closure of the aperture detected by the opening/closing detection means.
  8. 8. The lid opening/closing system according to claim 7, further comprising a purge nozzle capable of supplying the predetermined gas to the container through the aperture of the container, wherein the control means performs the start and stop of the supply of the predetermined gas by the purge nozzle in response to the detection of the opening/closing of the lid by the detection means.
  9. 9. The lid opening/closing system according to claim 6, wherein the container further includes at least one discharge port provided on a wall surface of the container main body and capable of discharging gases to the outside, and the system further comprises a discharge valve for discharging gases from within the container in conjunction with the discharge port.
  10. 10. The lid opening/closing system according to claim 6, further comprising:
    an enclosure arranged in the minute space in series with the first aperture to cover the moving space of the door and constitute a second minute space, the enclosure having a second aperture through which the first aperture and the minute space communicate with each other and the mechanism for transporting the object to be housed is allowed to pass along with the object to be housed; and
    a curtain nozzle located in a portion above the upper edge of the first aperture inside the enclosure and capable of supplying the predetermined gas along a direction from the upper edge toward the lower edge of the first aperture,
    wherein the enclosure includes a gas outlet port from which the gas is allowed to flow out into the minute space along a direction in which the gas flows.
US14095173 2012-12-04 2013-12-03 Lid opening/closing system for closed container, and substrate processing method using the same Pending US20140157722A1 (en)

Priority Applications (8)

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JP2012-264903 2012-12-04
JP2012264903 2012-12-04
JP2013129664 2013-06-20
JP2013-129664 2013-06-20
US201361842600 true 2013-07-03 2013-07-03
JP2013-243838 2013-11-26
JP2013243838A JP6206126B2 (en) 2012-12-04 2013-11-26 A substrate processing method using the cover opening and closing system and the system of the sealed container
US14095173 US20140157722A1 (en) 2012-12-04 2013-12-03 Lid opening/closing system for closed container, and substrate processing method using the same

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Effective date: 20140212