Wafer restraining system

Abstract

Disclosed is an apparatus and method for restraining flat objects such as semiconductor wafers within a cassette placed inside a box or pod to prevent movement or vibration of the flat objects during storage or transport. A flexible or inflatable tube contacts and conforms to the edge of the objects to eliminate movement and provide vibrational damping without hard surface contact or damage. The tube may be deflated or removed from contact with the wafers to allow removal of the wafers from the cassette.

What is claim is: 
     
       1. Apparatus for holding a plurality of semiconductor wafers having edges to be transported in a clean room environment comprising: a holder for holding said plurality of semiconductor wafers; and   an elastically deformable member having a conforming surface which deforms upon contact with said edges to form bulges in said surface around the edges of said semiconductor wafers to dampen movement of said semiconductor wafers.   
     
     
       2. Apparatus of claim 1, wherein said elastically deformable member comprises an inflatable tube. 
     
     
       3. Apparatus of claim 2, wherein said tube is adapted to be inflated at atmospheric pressure and deflated by application of a vacuum. 
     
     
       4. Apparatus of claim 1, wherein said holder comprises a cassette for holding said semiconductor wafers. 
     
     
       5. Apparatus of claim 1, further comprising a pod containing said holder; wherein said pod comprises a removable door having an internal surface and said deformable member is attached to said internal surface of said door; and wherein said deformable member comprises an inflatable tube having an internal cavity, and said apparatus further comprises a valve passing through said door, into said internal cavity of said tube, said valve operable to vent the internal cavity of said tube. 
     
     
       6. Apparatus for containing a plurality of semiconductor wafers having edges, said apparatus comprising: a) a cassette having a plurality of slots positioned to hold said semiconductor wafers in a parallel, stacked configuration;   b) a pod having a plurality of sides and a door, and designed to contain one or more of said cassettes; and   c) a flexible tube attached inside said pod in a position to contact one or more said wafers, said tube having a surface deforming upon contact with said one or more wafers to form bulges around one or more said edges and to provide vibration damping to said plurality of semiconductor wafers when said cassette holding said wafers is contained in said pod.   
     
     
       7. Apparatus of claim 6, wherein said tube is an inflatable tube having an internal cavity. 
     
     
       8. Apparatus of claim 7, further comprising a valve extending through one of said sides, and providing fluid communication between said internal cavity of said inflatable tube and the outside of said box; and wherein said valve is operable to control inflation and deflation of said inflatable tube. 
     
     
       9. Apparatus of claim 7 further comprising a valve extending through said door, and providing fluid communication between said internal cavity of said inflatable tube and the outside of said box; and wherein said valve is operable to control inflation and deflation of said inflatable tube. 
     
     
       10. A method for transporting semiconductor wafers having edges in a clean room environment comprising: holding said semiconductor wafers having edges in a slotted cassette; and   dampening vibrational movement in said semiconductor wafers by contacting said semiconductor wafers with a pliant member having a surface deformable upon contact with said edges to conform and deform around said edges to prevent motion in directions parallel and perpendicular to the plane of said semiconductor wafers by means of bulges formed in said surface of said pliant member around the edges of said semiconductor wafers.   
     
     
       11. The method of claim 10, wherein said pliant member comprises an inflatable tube. 
     
     
       12. An apparatus for transporting a plurality of semiconductor wafers comprising: a container holding an array of parallel slots adapted to receive a semiconductor wafer in each slot with an edge of each semiconductor wafer protruding from its slot, said container having an opening and including a closure member to close the opening, said container and opening adapted to receive said semiconductor wafers with a space between the edges of the semiconductor wafers and an opposing surface of the container; and   an elastically deformable member interposed between said protruding edges and said opposing surface, said deformable member having a surface deformable upon contact with said edges to form bulges around said edges when the container is closed to restrain movement of said semiconductor wafers in said slots.   
     
     
       13. The apparatus of claim 12 wherein said elastically, deformable member comprises an inflatable member inflatable from outside said container. 
     
     
       14. The apparatus of claim 12 wherein said opening lies opposite said protruding edges, and said elastically deformable member is supported by said closure member. 
     
     
       15. Apparatus for transporting a plurality of semiconductor wafers in a clean room environment, comprising: a slotted cassette adapted to hold a plurality of semiconductor wafers side-by-side in an array with edges of the semiconductor wafers protruding form the slots;   a box having enclosing surfaces and an opening in one of said enclosing surfaces;   said box adapted to receive said cassette through said opening with said edges facing an opposite enclosing surface and defining a space between said edges and said opposite enclosing surface;   said box including a closure member adapted to close said opening; and   an elastically compliant member adapted to be positionable in the space between said edges and said opposite enclosing surface, said compliant member having a conforming surface adapted to contact and correspondingly form bulges around said edges when said opening is closed to dampen movements of said semiconductor wafers in said slots.   
     
     
       16. The apparatus of claim 15 wherein said elastically compliant member comprises a plastic tube. 
     
     
       17. The apparatus of claim 16 wherein said compliant member is hollow and inflatable and said apparatus includes a conduit extending from said inflatable member. 
     
     
       18. The apparatus of claim 17 in which the container comprises a cassette. 
     
     
       19. A method of transporting in a clean room environment a slotted holder containing semiconductor wafers in the slots of the holder which comprises: enclosing the holder and semiconductor wafers in a pod having enclosing surfaces with edges of the semiconductor wafers protruding from the slots in spaced relation with an opposite enclosing surface of the pod to define a space between the opposite enclosing surface and the edges; and   contacting the protruding edges from within said space with a member having a pliant surface such that said pliant surface deforms to form bulges around said edges to dampen movements of the semiconductor wafers within the slots.   
     
     
       20. An apparatus for restraining a plurality of semiconductor wafers having edges comprising: a holder for holding said semiconductor wafers; and   a soft elastomeric restraining member adapted to conform and deform around edges of a plurality of semiconductor wafers upon contact with said edges and to return to an original shape when removed from said edges.   
     
     
       21. Apparatus of claim 20, wherein said member conforms to dimensional variations of said edges of said plurality semiconductor wafers.