|Veröffentlichungsdatum||23. Sept. 2008|
|Eingetragen||4. Dez. 2002|
|Prioritätsdatum||6. Jan. 1999|
|Auch veröffentlicht unter||US6082540|
|Veröffentlichungsnummer||10190430, 190430, US RE40513 E1, US RE40513E1, US-E1-RE40513, USRE40513 E1, USRE40513E1|
|Erfinder||Dennis J. Krampotich, D. Kerry Kiser|
|Ursprünglich Bevollmächtigter||Entegris, Inc.|
|Zitat exportieren||BiBTeX, EndNote, RefMan|
|Patentzitate (15), Referenziert von (7), Klassifizierungen (8), Juristische Ereignisse (4)|
|Externe Links: USPTO, USPTO-Zuordnung, Espacenet|
This invention relates to carriers for wafers that are processed into semiconductor units, more particularly, the invention relates to sealable enclosures for holding wafers in a horizontal orientation.
Semiconductor wafers are subjected to numerous steps during processing in various pieces of processing equipment. The wafers must be transported from workstation to workstation and often must be temporarily stored in order to accommodate the necessary processing steps. Usually such transport and storage is accomplished by putting the wafers into sealed containers to minimize exposure of the wafers to environmental contaminants.
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.
Numerous configurations of carriers have been previously known for handling, storing, and shipping wafers. A common component in carriers configured as closable containers is a molded plastic member known as a cushion to stabilize the positioning of wafers in the container. Such shipping containers with cushions have been previously known as disclosed, for example, in U.S. Pat. Nos. 4,043,451; 4,248,346; 4,555,024; 5,253,755; 5,273,159 and 5,586,658. These types of containers typically include vertical wafer-receiving channels and cushions at the upper and/or lower ends. Various configurations of cushions have been utilized for securing the vertically oriented wafers in the channels. For example, the cushions may comprise fingers that extend from or attach to the cover for gripping the wafer edges. These cushions conventionally have a wafer engaging portion with a V-shaped cross section. An integral finger portion connects to the wafer engaging portion and also connects to a base attached to the cover.
Such conventional cushions are manufactured from relatively pliable plastic such as polyethelene, or even more pliable plastics, to minimize the pressure exerted on each wafer edge. Such materials are subject to creep and the loss of resiliency and cushioning performance. These cushions may be integral with the container closure (see for example U.S. Pat. No. 5,586,658 assigned to owner of the instant invention) or may be attached to the closure by various means such as a snap-in arrangement (see U.S. Pat. No. 4,880,116 to Kos). Highly stable and precise attachment of cushions to door have been elusive. Metallic fasteners, due to their potential of creating metal particulars are to be avoided.
These shipping devices have typically been designed to transport wafers or disks in a vertical orientation from place to place, whereas most processing workstations require that wafers processing carriers retain wafers horizontally. Thus wafers must be reoriented for many processing steps. Where the entire container is reoriented with wafers in place, the wafers can shift and scrape against the wafer pockets producing particulates.
Corresponding with the increase in the size of wafers being processed into semiconductor chips, the industry is also shifting from vertically oriented containers to containers that maintain the wafers horizontally. Forward wafer restraints for such carriers have comprised a cushion member attached to the door and extending vertically and transverse to the planes of the wafers to engage each wafer along a vertical line. The cushions may be fixed to the inside surface of the door such that they engage the stack of wafers as the door is inserted into the door frame or alternatively, the cushions may be attached to mechanisms in the door to extend and retract the cushions independently of the movement of the door into and out of the door frame. Known cushions for such horizontal containers consist of a vertically positioned resilient rod or bar or a vertically oriented elongate base member with a plurality of fingers extending therefrom to engage the edge of each sequential wafer. See U.S. Pat. No. 5,711,427 which is incorporated herein by reference.
With the vertically oriented carrier, wafer receiving channels are designed to hold wafers firmly with a minimum of horizontal movement. With the horizontally oriented carrier, wafer receiving slots are larger than the thickness of wafers to enable wafers to be inserted horizontally into containers and lowered onto a seating position on wafer shelves. To avoid particulate generation, there will ideally be no sliding of the wafer on the wafer shelves. In such carriers, now known as transport modules, contact with the wafers by the carrier is desirably kept to a minimum. For example, as disclosed in U.S. Pat. No. 5,788,082, which is incorporated herein by reference, see
The 300 mm wafers are significantly heavier than previous 200 mm and smaller wafers. Although this weight operates to effectively maintain the wafers seated on the wafer shelves, the weight also renders traditional resilient cushioning fingers, such as made from polyethelene, ineffective to maintain the radial position of the wafers on the shelves. Any sliding of the wafer on the shelves has the potential of creating damaging particulates. Thus a more rigid cushion is needed beyond conventional polyethelene. Use of stiffer materials which would have a correspondingly greater spring constant would require greater precision in manufacturing. Deflection of the fingers would need to be less and more carefully controlled to avoid putting excessive force on the edge of the wafers subjecting them to risk of damage. Moreover, the cushioning members would need to be securely anchored to the closure to maintain the controlled deflection and controlled force on the wafers. These requirements are difficult to accomplish in the sizes associated with 300 mm transport modules.
Conventional individual resilient fingers for engaging wafers, whether for horizontal or vertically oriented wafers, have a configuration of a V-shape with a bottom wafer seating portion that is sized to the thickness of the wafer to hold the same securely. Moreover, each wafer is supported at the same circumferential position. That is, the cushions are arranged in a linear row or column. The spacing between horizontal wafers in 300 mm front opening carriers has been standardized by the industry to allow maximum density in the carriers while still allowing insertion room for a robotic arm for insertion and removal. This minimal amount of vertical space makes it extremely difficult to manufacture cushions with vertically aligned wafer engaging fingers and wafer engaging portions that have any allowance for slight vertical misalignments in the wafer engaging portions such as might be caused by variation in manufacture of the cushions or wafers misaligned on the shelves. Thus, a wafer cushion system for providing a forward constraint for sealable wafer enclosures is needed that provides a precise control of wafer engagement, that is stiffer than traditional cushions, that provides for manufacturing variations, wafer-cushion engagement portion misalignments, and that has minimal contact with the wafers.
In a preferred embodiment of the invention, a transport module suitable for 300 mm wafers has a cushioning system that attaches to the interior of an enclosure door having a pair of upright parallel cushions, each comprising an elongate base portion with a plurality of integral fingers extending at an acute angle from the base members. Each sequential finger of each cushion engaging every other wafer. Each finger having an finger portion and a wafer engaging portion. The wafer engaging portion comprising a curved convex surface to provide minimal vertical line contact with the circumferential outer surface of the wafer without providing axial constrainment of the wafer. The base portions are attached to the inside facing door panels by a plurality of attachment portions each comprising a split shank portion that extends through the aperture and a plurality of flange portions on the ends of the split shank portions for securing the base portions to the inside panel. An O-ring may be positioned on the shank portion for sealing the connection. Additional extension members may extend intermediate the finger portions to provide a contact point laterally displaced from the base member such that when the wafer engagement portions are loaded by engagement with the wafers, the connection of the attachment portion to the interior door panel operates as a fulcrum to precisely control the positioning, holding force, and deflection of the fingers.
It is an object of the particular embodiments of the invention to provide forward constraint of wafers in a front opening wafer enclosure with minimal wafer contact by the cushion.
It is an object of particular embodiments of the present invention to provide a wafer carrier with cushions steadfastly secured to the inside panel of the wafer container door to provide precise control of the engagement of the wafers.
Another object and advantage of particular embodiments of the invention is to provide minimal contact with the wafer to reduce contamination of wafers during transport and storage.
Additional objects, advantages, and novel features of the invention will be set forth in part in the description which follows, and in part will become apparent to those skilled in the art upon examination of the following or may be learned by practice of the invention. The objects and advantages of the invention may be realized and attained by means of the instrumentalities and combinations particularly pointed out in the appended claims.
Another object and advantage of particular embodiments is that the wafer engagement portions allow for misalignment between the wafers and said wafer engagement portions.
It is understood that the above figures are for illustrative purposes only and are not meant to limit the scope of the claimed invention.
Details of the construction of a preferred embodiment of the cushions and the attachment of the cushions to the door are disclosed in
The cushions are each vertically oriented with the wafer engaging fingers extending in a lateral direction from the base portion at an acute angle relative to the inside surface 38. Also extending laterally in the same lateral direction are a plurality of extension members 76 which each include an intermediate section 78 and a contact portion 80 which is in contact engagement with the inwardly facing surface 38 of the wall 42.
Extending from the base portion 64 of each cushion is a pair of attachment portions 86 each of which comprises a shank portion 88 and a flange 90. The shank portion is configured as a split shank to define a plurality of prongs 92 and a plurality of flange portions 93 on the ends of the split shank portions 94.
Details of the attachment of the cushions 58 to the inwardly facing wall 42 are shown in
Note that in particular embodiments the wafer engagement portions of each particular cushion only engage every other wafer. This allows the extended width 124 of the wafer contact surface 120 which would not be possible with conventional aligned wafer engagement portions.
Another aspect of the invention is provided by the extension members 76. For manufacturing and assembly ease, each cushion is attached to the inside-facing wall of the door at only two connection points 170. Said connection points are positioned in a vertical line at the base portion 64. To provide precise positioning and control of the engagement of the wafers by the wafer engagement portions of the cushions and additional support displaced from the vertical line of the connection points is provided by said extension member. The wafer engaging fingers 72 is cantilevered outwardly from the base member. The extension member also is cantilevered out from the base member but is loaded in the opposite direction. The extension member may be preloaded or stressed before wafer engagement such as by molding the cushion with the contact portion having an interference fit with the interiorly facing wall 42. Alternatively, the cushion can be molded with the contact portion positioned approximately at the interiorly facing surface.
The extended width 124 of the contact surface of the wafer engagement portion allows for variations in the positioning of said engagement portions that might occur during molding or due to other factors such as wear. Additionally, the extended width allows for slight misalignment of the door.
In configurations where both the extension member and wafer engagement portion are laterally displaced from the connections 170, precise deflection of the wafer engaging fingers is provided. The connection point 170 operates as a fulcrum relative to the extension member and the wafer engagement arm.
In the ideal situation, the cushion may be molded principally of polyetheretherketone (PEEK). Polytetrafluorethylene (PTFE) may be added in small quantities, for example, 5% PEEK provides a fairly stiff and resilient cushion. An ideal deflection of the wafer engagement portion has been found to be 0.040 inches.
The present invention may be embodied in other specific forms without departing from the spirit or essential attributes thereof; and it is, therefore, desired that the present embodiment be considered in all respects as illustrative and not restrictive, reference being made to the appended claims rather than to the foregoing description to indicate the scope of the invention.
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|Zitiert von Patent||Eingetragen||Veröffentlichungsdatum||Antragsteller||Titel|
|US7806642 *||20. Apr. 2005||5. Okt. 2010||Panasonic Corporation||Receiver for component feed plates and component feeder|
|US7971722 *||8. Aug. 2008||5. Juli 2011||Gudeng Precision Industral Co, Ltd||Wafer container with restrainer|
|US8474626||23. Apr. 2010||2. Juli 2013||Gudeng Precision Industrial Co., Ltd.||FOUP and robotic flange thereof|
|US8556079||29. März 2010||15. Okt. 2013||Texchem Advanced Products Incorporated Sdn Bhd||Wafer container with adjustable inside diameter|
|US20070227941 *||20. Apr. 2005||4. Okt. 2007||Shoriki Narita||Receiver for Component Feed Plates and Component Feeder|
|US20090032433 *||8. Aug. 2008||5. Febr. 2009||Chin-Ming Lin||Wafer container with restrainer|
|US20110005966 *||13. Jan. 2011||Ming-Chien Chiu||Foup and robotic flange thereof|
|US-Klassifikation||206/445, 206/711, 206/454|
|Internationale Klassifikation||B65D85/86, H01L21/673, B65D85/30|
|9. März 2009||AS||Assignment|
Owner name: WELLS FARGO BANK, NATIONAL ASSOCIATION, AS AGENT,
Free format text: SECURITY AGREEMENT;ASSIGNOR:ENTEGRIS, INC.;REEL/FRAME:022354/0784
Effective date: 20090302
Effective date: 20090302
Owner name: WELLS FARGO BANK, NATIONAL ASSOCIATION, AS AGENT,M
Free format text: SECURITY AGREEMENT;ASSIGNOR:ENTEGRIS, INC.;REEL/FRAME:022354/0784
|17. Aug. 2011||AS||Assignment|
Owner name: ENTEGRIS, INC., MASSACHUSETTS
Free format text: RELEASE BY SECURED PARTY;ASSIGNOR:WELLS FARGO BANK NATIONAL ASSOCIATION;REEL/FRAME:026764/0880
Effective date: 20110609
|11. Jan. 2012||FPAY||Fee payment|
Year of fee payment: 12
|11. Jan. 2012||SULP||Surcharge for late payment|
Year of fee payment: 11