Seal for a joint or juncture – Seal between fixed parts or static contact against... – Contact seal for other than internal combustion engine – or...
Reexamination Certificate
1999-01-06
2002-03-12
Browne, Lynne H. (Department: 3626)
Seal for a joint or juncture
Seal between fixed parts or static contact against...
Contact seal for other than internal combustion engine, or...
C277S630000, C277S644000, C220S378000, C220S795000, C206S710000
Reexamination Certificate
active
06354601
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to enclosures. More particularly, it relates to sealable enclosure for holding wafers to be manufactured into semiconductors.
Semiconductor wafers are subjected to numerous steps during processing. This usually entails transporting a plurality of wafers from one workstation to another for processing by specialized equipment. As part of the processing procedure, wafers may be temporarily stored or shipped in containers to other plants or to end users. Such intra and extra movements may generate or expose the wafers to potential wafer ruining contaminants. In order to reduce the deleterious effect of contaminants on wafers, specialized containers have been developed to minimize the generation of contaminants and to isolate wafers from contaminants exterior to the containers. A principal feature common to these devices is that they are provided with removable doors or closures which seal or are sealed such as by tape when closed.
As semiconductors have become larger in scale, that is, as the number of circuits per unit area has increased, contaminants in the form particulates have become more of an issue. The size of particulates that can destroy a circuit has decreased and is approaching the molecular level. Particulate control is necessary during all phases of manufacturing, processing, transporting, and storage of semiconductor wafers. The industry is moving toward processing larger and larger wafers into semiconductors. Three hundred millimeter (300 mm) wafers are now commonplace.
Wafer carriers may be made of a variety of materials which in almost all cases comprised thermoplastics. Early containers including, enclosures and closures, were made of highly moldable plastics such as polyethelene, see U.S. Pat. No. 4,248,346, and some held rigid h-bar carriers such as disclosed in U.S. Pat. No. 5,273,159, and some comprise polycarbonate enclosure portions with molded in slots and with softer more resilient covers. See for example U.S. Pat. No. 5,586,658.
Such containers typically relied on an enclosure portion to cover contact for providing the sealing of the container. Other containers, primarily for use within semiconductor fabrication facilities, have both a door to enclosure portion seal and also have the capability to sealingly engage to process equipment. Such container have been termed “SMIF pods” (sealed mechanical interface) where the door closes an open bottom of the container portion, or transport modules, where the door closes an open bottom. These containers are subjected to very demanding structural requirements and performance requirements. For example, they must mechanically latch by robotic or manual means and must of course provide exceptional isolation, such as being hermetically sealable simply by closing the door. For containers for 300 mm wafers that are utilized in fabs, front opening modules are being utilized. Conventional seals for both SMIF pods and transport modules have been relatively simple elastomeric seals that are simply compressed between the door and enclosure portion in an axial direction to provide the seal. As such, the seal contact with the door is aligned with the seal contact with the door frame. Such sealing, particularly where polycarbonate is the contacted by the elastomeric seal, tend to stick excessively and provide inconsistent opening, reduced life expectancy of the seal and inadequate sealing.
A seal is needed for wafer enclosures that is not subjected to direct compression as it seals.
Better performing and longer lasting seals are needed for wafer enclosures.
SUMMARY OF THE INVENTION
A wafer container comprising an enclosure portion with a door frame defining an opening for insertion and removal of wafers and a door for insertion into the door frame for closing the opening and sealing with the door frame has an improved elastomeric seal. In a preferred embodiment of the invention an elastomeric seal encircles the door, is partially inset in a groove in the door, and has a cantilevered portion extending laterally outwardly from the door to engage a sealing surface of the door and a laterally displaced sealing surface of the door frame when the door is seated. Thus a seal can be provided that is effected almost totally by flexure of the cantilevered portion rather than by compression of the seal.
An object and advantage of preferred embodiments of the invention is that a desired sealing force between the door frame and the seal can be easily designed into the cushion by shifting the position of the pedestal portion.
A further object and advantage of preferred embodiments of the invention is that the sealing is not provided by compressing an elastomeric seal, rather it is provided by flexing a cantilevered portion by the insertion of the door.
A further object and advantage of particular embodiments of the invention is that a very soft seal of high integrity is provided which essentially eliminates sticking between the door and door frame.
A further object and advantage of preferred embodiments of the invention is that the seal can be easily replaced when it is worn out or when different sealing characteristics are desired.
REFERENCES:
patent: 4434909 (1984-03-01), Ott
patent: 4804086 (1989-02-01), Grohrock
patent: 5024329 (1991-06-01), Grohrock
patent: 5199369 (1993-04-01), Meyer et al.
patent: 5611452 (1997-03-01), Bonora
patent: 5743424 (1998-04-01), Murata et al.
patent: 5971191 (1999-10-01), Yamada et al.
patent: 826 702 (1952-01-01), None
Kiser D. Kerry
Krampotich Dennis J.
Peterson Michael D.
Browne Lynne H.
Fluoroware, Inc.
Patterson Thuente Skaar & Christensen P.A.
Peavey Enoch
LandOfFree
Seal for wafer containers does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Seal for wafer containers, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Seal for wafer containers will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2842009