Abstract:
A system of moving magnets for sealing a container may include a plurality of moveable magnets disposed near a perimeter of a container door and a rotatable linkage hub positioned within the perimeter of the container door. In addition, the system may include a plurality of control linkages connecting each of the plurality of moveable magnets to the linkage hub so that rotating the linkage hub causes the control linkages to move the moveable magnets between a sealed position and an open position. Alternatively, the moveable magnets may be connected to each other by a magnet positioning mechanism to physically move the magnets along a path near the perimeter. A plurality of static magnets may be disposed near an opening sized to receive the container door and positioned to form a magnetic seal with the moveable magnets when the moveable magnets are positioned at the sealed position.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of the following provisional applications, each of which is hereby incorporated by reference in its entirety: 
     U.S. Provisional Application Ser. No. 61/049,440 filed May 1, 2008 and U.S. Provisional Application Ser. No. 61/057,170 filed May 29, 2008. 
     This application is a continuation-in-part of U.S. application Ser. No. 12/131,024 filed May 30, 2008 which is hereby incorporated by reference in its entirety. 
    
    
     BACKGROUND 
     1. Field 
     The methods and systems disclosed herein relate to magnetically sealable substrate containers. 
     2. Description of the Related Art 
     Currently, standards for the semiconductor industry describe mechanically sealing boxes (Front Opening Unified Pods—FOUPs, SEMI E47.1, E57). While techniques are generally known for mechanically operating seals, a mechanical seal has a number of disadvantages. The physical mechanisms for sealing can generate particles where latches engage. It is also difficult to achieve a uniform seal on a mechanically secured door, and any force transmission can damage the weakest part of a transmission chain. While magnetic seals have been proposed to avoid some of these disadvantages, there remains a need for controllable magnetic seals for substrate containers. 
     SUMMARY 
     A substrate container may provide an air-tight enclosure for storing or transporting substrates. The environment of the substrate container may include a vacuum atmosphere, an air atmosphere, an inert gas atmosphere (e.g. Argon or Nitrogen), and the like. An arrangement of moveable magnets in a door of the container and corresponding magnets or magnetically attractive elements in the container body may facilitate securing the container door to the container body to enable the air-tight seal. 
     In an aspect of the invention, methods and systems for sealing a container include a plurality of moveable magnets disposed near a perimeter of a container door; a linkage hub positioned within the perimeter of the container door; and a plurality of control linkages connecting each of the plurality of moveable magnets to the linkage hub so that operating the linkage hub causes the control linkages to move the moveable magnets between a sealed position and an open position. In the aspect, operating the linkage hub comprises rotating the linkage hub. Further in the aspect, rotating the linkage hub clockwise causes the moveable magnets to move to the sealed position. Also, rotating the linkage hub counter-clockwise may cause the moveable magnets to move to the open position. 
     In the aspect, the system for sealing a container is sealed within the container door. 
     Further in the aspect, the linkage hub is magnetically attractive. The methods and systems may also include a magnet for positioning over the rotatable linkage hub and for operating the linkage hub via magnetic attraction of the magnet to the hub. 
     In the aspect, the moveable magnets are disposed to provide an evenly distributed sealing force when the moveable magnets are positioned in the sealed position. 
     The aspect may further include at least one return spring positioned to return the moveable magnets to the sealed position. The return spring acts on at least one of the plurality of magnets or the linkage hub. 
     In another aspect of the invention, methods and systems may include a plurality of moveable magnets disposed near a perimeter of a container door; a magnet positioning mechanism connecting to each of the magnets to control movement of the magnets in relation to a sealing position; a container with an opening shaped to receive the door thereby closing the opening; and a plurality of magnetically attractive elements disposed near the opening and positioned to form a magnetic seal with the moveable magnets when the moveable magnets are positioned at the sealing position. 
     In the aspect, the magnet positioning mechanism includes a linkage hub connected to the plurality of moveable magnets with linkages. The magnet positioning mechanism may include a rotating hub for moving the moveable magnets to the sealed position in response to a clockwise rotation of the rotating hub. The magnet positioning mechanism may include a rotating hub for moving the moveable magnets from the sealed position in response to a counter-clockwise rotation of the rotating hub. 
     In the aspect, the system sealing a container is sealed within the container door. 
     Also, in the aspect, the moveable magnets are disposed to provide an evenly distributed sealing force when the moveable magnets are positioned in the sealed position. 
     In yet another aspect of the invention, methods and systems for magnetically sealing a substrate container may include connecting a plurality of moveable magnets with a mechanism for simultaneously moving the moveable magnets among a sealed position, a neutral position, and an opened position, wherein neighboring moveable magnets have opposing magnetism; positioning a plurality of static magnets to align with each of the moveable magnets when the moveable magnets are in one of the sealed position and the opened position, wherein the static magnets attract the moveable magnets when they are moved to the sealed position and the static magnets repel the moveable magnets when they are moved to the opened position; positioning a first portion of the substrate container that includes the moveable magnets against a second portion of the substrate container that includes the static magnets to form a closed container; and actuating the mechanism to move the moveable magnets to the sealed position. The aspect may further include unsealing the substrate container by actuating the mechanism to move the moveable magnets to the neutral position. The aspect may further include opening the substrate container by actuating the mechanism to move the moveable magnets to the opened position. In the aspect, opening the substrate container is facilitated by the static magnets repelling the moveable magnets. 
     In yet another aspect of the invention, methods and systems may include a plurality of first magnets disposed near a perimeter of a container door; a plurality of electromagnets disposed near a perimeter of a container door counteracting each of the first magnets to physically cancel the magnetic force of the first magnets; a container with an opening shaped to receive the door thereby sealing the opening; and a plurality of static magnets or magnetic material disposed near the opening and positioned to align with the first magnets, wherein each static magnet or magnetic material is next to an opposing first magnet. In the aspect, a power supply may activate the electromagnets in order to remove the container door. 
     In yet another aspect of the invention, methods and systems may include at least one moveable magnet disposed near each edge of a container door; a plurality of mechanical springs connecting the moveable magnets to the container door, the springs for positioning the moveable magnets in a sealing position; a magnet positioning mechanism connecting to each of the moveable magnets to facilitate opposing the plurality of springs thereby moving the magnets from the sealing position; a container with an opening shaped to receive the door thereby sealing the opening; and at least one magnetically attractive element disposed near each edge of the opening and positioned to form a magnetic seal with the moveable magnets when the moveable magnets are positioned at the sealing position. In the aspect, the magnet positioning mechanism controls the movement of the magnets between the sealing position and an open position. 
     In yet another aspect of the invention, methods and systems may include a plurality of magnets moveably disposed near a perimeter of a container door, wherein each magnet is next to an opposing magnet; a magnet positioning mechanism connecting each of the magnets to physically move the magnets along a path near the perimeter; a container with an opening shaped to receive the door thereby sealing the opening; and a plurality of static magnets disposed near the opening and positioned to align with the moveable magnets, wherein each static magnet is next to an opposing magnet. In the aspect, the magnet position mechanism includes a chain to connect each of the magnets and a gear train engaged with the chain to move the magnets. 
     In yet another aspect of the invention, methods and systems may include accessing an interior of a substrate container that may include a five sided body forming a container with an opening sized to accept a top for sealing an interior of the sealed container; a gasket for sealing the top to the body to form an air-tight seal; a pressure sensitive membrane in a side of the body for exhausting the interior atmosphere; and an intake membrane in the top separating the interior atmosphere from an exterior environment and for receiving a hollow needle for accessing the interior atmosphere from the exterior environment while maintaining the air-tight seal. In the aspect, the pressure sensitive membrane facilitates exhausting the interior atmosphere to the exterior environment based on an interior atmosphere pressure threshold. In the aspect, the interior atmosphere pressure threshold is based on a difference between the interior atmosphere and the exterior environment. 
     In the aspect, the hollow needle is further connected to a pressurized gas supply for introducing the gas into the container thereby causing the interior atmosphere to be exhausted through the pressure sensitive membrane so that the interior atmosphere is replaced with the gas. The gas is an inert gas and may be one of air, argon, and nitrogen. 
     In the aspect, the pressure sensitive membrane allows for small pressure differentials between the interior atmosphere and the exterior environment 
     These and other systems, methods, objects, features, and advantages of the present invention will be apparent to those skilled in the art from the following detailed description of the preferred embodiment and the drawings. All documents mentioned herein are hereby incorporated in their entirety by reference. 
    
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
       The invention and the following detailed description of certain embodiments thereof may be understood by reference to the following figures: 
         FIG. 1  depicts a section view of a substrate container with a mechanically operated seal. 
         FIG. 2A  depicts a section view of a door of the embodiment of  FIG. 1  with the mechanically operated seal in an open or unsealed position. 
         FIG. 2B  depicts a section view of a door of the embodiment of  FIG. 1  with the mechanically operated seal in a closed or sealed position. 
         FIG. 3  depicts a top view of a magnetically operated latch. 
         FIG. 4  depicts a section view of a magnetic door seal. 
         FIG. 5A  depicts a section view of a door with spring positioned magnets in an unsealed position. 
         FIG. 5B  depicts a section view of a door with magnets in a sealed position. 
         FIG. 6  depicts a mechanism for mechanical actuation of a magnetic door seal. 
         FIG. 7  depicts an electronic control for magnetically sealing a substrate container. 
         FIG. 8  depicts a top view of an electronically controlled magnetically sealed door of a substrate container. 
         FIG. 9  depicts a top view of a door with moveable magnets for sealing the door to a container. 
         FIG. 10  depicts the embodiment of  FIG. 9  with the magnets moved to an alternate position. 
         FIG. 11A  depicts aligned magnets from the embodiment of  FIG. 9 . 
         FIG. 11B  depicts non-aligned magnets from the embodiment of  FIG. 10 . 
         FIG. 12A  depicts aligned attracting magnets. 
         FIG. 12B  depicts non-aligned magnets. 
         FIG. 12C  depicts aligned opposing magnets. 
         FIG. 13  depicts a magnetically sealed container with a nitrogen purge port. 
         FIG. 14  depicts an application of the embodiment of  FIG. 13 . 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  is a side view of a Front Opening Unified Pod (“FOUP”) container with a mechanically operated seal. In general the FOUP container  1000  has a gasket  1010  that maintains an air tight seal, and a door latch mechanism that secures a door  1020 . Wafers or similar substrates may be stored within the FOUP container  1000 . 
       FIG. 2A  shows a mechanical door latch in an open position. A seal device  2010  or the like is coupled by a linkage  2020  to an engagement disk  2030  operative to collectively apply a closing force to the door  1020 . 
       FIG. 2B  shows the mechanical door latch in a closed position, with applied latch forces and the resulting closing force indicated by arrows. 
     In general, the various mechanisms for sealing and opening a FOUP door may be activated by application of magnetic force. 
       FIG. 3  shows a magnetically operated latch. A magnet positioning mechanism that may include a linkage hub  3010  and linkages  2020  may provide physical access to the linkage hub  301  to control the linkages  2020  that physically control movement of seal devices  2010 . Seal device  2010  may be formed of a magnetic material. By operating the linkage hub  3010 , the seal devices  2010  may be moved into and out of position to magnetically seal the door to a FOUP or the like. The magnet positioning mechanism and seal devices  2010  may be enclosed entirely within the door, thus mitigating risks of particle generation/contamination within the FOUP. By distributing a number of magnetic seal devices  2010  about the perimeter of a door, a more constant, evenly distributed closing force can be applied to the door perimeter and consequently to the gasket  1010 . Corresponding magnets or magnetically attractive elements within the FOUP around the perimeter of an opening for the door may optionally be employed to provide greater closing force. In embodiments, electrical coils or the like may be positioned about the seal devices  2010  so that local magnetic forces can be temporarily reduced to unseal the door. Although the embodiment of  FIG. 3  depicts the magnet positioning mechanism as a hub with linkages, other magnet positioning mechanism, such as electronically controlled motors, mechanical slides, springs, magnetically controlled positioning devices, and the like may be used in place of the hub and linkages. 
       FIG. 4  shows a magnetic door seal. Magnets may be attracted to other magnets or magnetically attractive material such as iron, steel, and the like. In the embodiment of  FIG. 4 , magnetically attractive elements  4010  within the FOUP  1000  may be positioned along the perimeter of an entrance thereto. Movable magnets  4020  may be provided within the door  1020  in positions that correspond to the magnetically attractive elements  4010 . The door  1020  may be configured with any suitable mechanical system to move the movable magnets  4020  into and out of alignment with the magnetically attractive elements  4010  to seal the door  1020  through magnetic attraction of the movable magnets  4020  and the corresponding magnetically attractive elements  4010 . 
       FIG. 5A  shows a door with moveable magnets in an unsealed position. A return spring  5010  or the like may be provided to assist in physical positioning of the magnets  4020 . 
       FIG. 5B  shows the door  1020  with magnets in a sealing or closed position. It will be understood that many magnet positioning mechanism including without limitation mechanical, electromechanical, or magneto-mechanical systems may be suitably adapted to move the magnets  4020  into and out of alignment with the magnetically attractive elements  4010  of the FOUP  1000  under user control. 
       FIG. 6  shows a mechanical control for magnetically sealing a FOUP door. In this embodiment, a linkage hub  6010  provides access for a user to physically operate the magnetic latch. Return springs  6020  may be provided to draw the magnets  6030  within the door into a position aligned with corresponding magnets (not shown) in a FOUP. Alternatively, return spring  6020  may be positioned to return the linkage hub  6010  to a home location that returns the magnets  6030  to a position aligned for sealing the FOUP. Linkages  6040  may be provided to mechanically couple the linkage hub  6010  and associated hardware to the magnets  6030  to permit movement of the magnets into and out of alignment with the FOUP magnets. It will be understood that, while magnets within the FOUP may be employed to increase the applied force of the magnetic seal, the FOUP may also, or instead, employ non-magnetized materials such as any suitable metal to attract the magnets of the door and provide a closing force to seal the FOUP. 
       FIG. 7  shows an electrical control for magnetically sealing a FOUP door. In this embodiment, an electrical coil  7010  provides a reverse magnetic field when current is applied through electrical contacts  7020  (wiring to coils not shown), thereby temporarily relieving the closing force of magnets  4020  that have a fixed position within the door  1020 . 
       FIG. 8  shows an electrical control for magnetically sealing a FOUP door. In this embodiment, permanent magnets  8010  may be positioned within or behind electrical coils  8020  that selectively create an opposing magnetic field when current is applied. Each coil  8020  may be wired to contacts  8030  on the door  1020  where a suitable control circuit and current source may be connected to control operation of the coils  8020  to selectively relieve closing force from the permanent magnets  8010 . It will be understood that in other embodiments, the coil may create a magnetic field to seal the door, although the desirability of this arrangement may depend on the length of time the door remains sealed in typical usage conditions. It will be understood that a combination of permanent magnets and electromagnets may be used in a suitable arrangement. 
       FIG. 9  shows a magnetically sealed wafer transport container including movable magnets. The movable magnets  4020  may be mounted to a magnet transport  9010 , such as a chain, cable, wire, or similar linkable device. The magnet transport  9010  may be mounted inside a box door enclosure. A gear, sheave, pulley, or similar device  9020  may allow the magnet transport  9010  to make a 90-degree turn. A linkage hub and gear train  9030  may drive the chain. The gear  9020  may be part of the gear train  9030 . The magnetically attractive elements  4010  may be mounted in the box frame. In some embodiments, the magnetically attractive elements  4010  and the magnets  4020  may be permanent magnets. As shown, the movable magnets  4020  may be positioned over the magnetically attractive elements  4010  resulting in a relatively high net force between the magnetically attractive elements  4010  and the magnets  4020  that holds the door closed. 
       FIG. 10  shows a magnetically sealed wafer transport container including movable magnets. The linkage hub  9030  may be rotated into an open position. This rotation may move the chain  9010  so as to position the movable magnets  4020  in a neutral position above gaps between the magnetically attractive elements  4010 . This may result in a relatively low net force between the magnetically attractive elements  4010  and the magnets  4020  that allows the door to be opened. 
       FIGS. 11A and 11B  show magnets from a door of a magnetically sealed wafer transport container. The magnetic direction  11020  of the movable magnets  11002  may be oriented in a first direction. The magnetic direction  11010  of the static magnets  11004  may be oriented in a second direction. The first direction may be substantially opposite the second direction so that aligning the moveable magnets  11002  and the static magnets  11004  may result in a relatively high net force between the magnets  11002  and  11004  that seals the door. When the magnets  11002  are moved to a non-aligned or neutral position relative to the static magnets  11004  as shown in  FIG. 11B , there may result a relatively low net force between the magnets  11002  and  11004  that allows the door to be opened. 
       FIGS. 12A ,  12 B, and  12 C show magnets from a door of a magnetically sealed wafer transport container. The movable magnets  11002  may be oriented in alternating, opposite directions  12020 . The static magnets  11004  may be oriented in alternating, opposite directions  12010 . Rotation of the gear  9020  may position the movable magnets  11002  to produce the depicted arrangements. 
     In  FIG. 12A , the movable magnets  11002  may be positioned over the static magnets  11004  and the coinciding directions  12020 ,  12010  may be substantially opposite each other. In this configuration, a relatively high net force between the magnets  11002  and  11004  may hold the door closed. 
     In  FIG. 12B , the movable magnets  11002  may be above the gaps between the static magnets  11004  in a neutral position, resulting in a relatively low net force between the magnets  11002  and  11004  that allows the door to be opened. 
     In  FIG. 12C  the movable magnets  11002  may be moved over the static magnets  11004  and the coinciding directions  12020 ,  12010  may be substantially the same as each other. In this configuration, an opposing force between the magnets  11002  and  11004  may assist in opening the door. 
     Current FOUPs are manufactured out of plastics. Wafers in the FOUP are exposed to air, which can have an impact on wafer surface conditions. Water vapor can react with the wafer surface. Oxygen can react with the wafer surface. Airborne Molecular Contaminants (primarily Hydrocarbons emitted by the plastics) can react with the wafer surface. For these reasons, the semiconductor industry is presently considering standards for purging FOUP enclosures with Nitrogen. There remains a need for a FOUP nitrogen purge technique that prevents over- or under pressurization and reliably couples and uncouples Nitrogen to a plastic FOUP enclosure. 
       FIG. 13  shows a nitrogen purging system for a FOUP. A FOUP  1000  may generally include a seal gasket  1010 , a FOUP door  1020 , and an exhaust permeable membrane  1030 , which allows for small pressure differentials to exist while venting excess pressure through the membrane. An intake gasket  1040 , which may be similar to gaskets used in pharmacy applications to remove liquid from vials, selectively receives a needle  1050  coupled to a nitrogen source. The needle  1050  may be movable under robotic or other electromechanical control to move into and out of the intake gasket  1040 . 
       FIG. 14  shows the needle  1050  of  FIG. 9  inserted into the intake gasket  1040 , after which nitrogen may be supplied through the needle  1050  into the FOUP  1000  interior to purge air or other gasses therefrom. 
     Having thus described several illustrative embodiments, it is to be appreciated that various alterations, modifications, and improvements will readily occur to those skilled in the art. Such alterations, modifications, and improvements are intended to form a part of this disclosure, and are intended to be within the spirit and scope of this disclosure. While some examples presented herein involve specific combinations of functions or structural elements, it should be understood that those functions and elements may be combined in other ways according to the present invention to accomplish the same or different objectives. In particular, acts, elements, and features discussed in connection with one embodiment are not intended to be excluded from similar or other roles in other embodiments. Accordingly, the foregoing description and attached drawings are by way of example only, and are not intended to be limiting. 
     All documents referenced herein are hereby incorporated by reference.