Classifications

• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
  • H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
  • H01L21/67—Apparatus 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
  • H01L21/673—Apparatus 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 using specially adapted carriers or holders; Fixing the workpieces on such carriers or holders
  • H01L21/6735—Closed carriers
  • H01L21/67366—Closed carriers characterised by materials, roughness, coatings or the like
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C45/00—Injection moulding, i.e. forcing the required volume of moulding material through a nozzle into a closed mould; Apparatus therefor
  • B29C45/14—Injection moulding, i.e. forcing the required volume of moulding material through a nozzle into a closed mould; Apparatus therefor incorporating preformed parts or layers, e.g. injection moulding around inserts or for coating articles
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C45/00—Injection moulding, i.e. forcing the required volume of moulding material through a nozzle into a closed mould; Apparatus therefor
  • B29C45/16—Making multilayered or multicoloured articles

Definitions

• This invention relates to wafer carriers. More particularly it relates to fire retardant wafer carriers.
• Carriers are generally configured to axially arrange the wafers or disks in article supports in the form of shelves or slots, and to support the wafers or disks by or near their peripheral edges.
• the wafers or disks are conventionally removable from the carriers in a radial direction upwardly or laterally.
• Carriers may have supplemental top covers, bottom covers, or enclosures to enclose the wafers or disks. Examples of specialized carriers and methods for forming them are disclosed in U.S. Patent Nos.
• carrier includes, but is not limited to: semiconductor wafer carriers such as H-bar wafer carriers, Front Opening Unified Pods (FOUPs), and Standard Mechanical Interface Pods (SMIFs); reticle carriers; WTP boxes, and other carriers used in the micro-electronic industry for storing, transporting, fabricating, and generally holding small electronic components such as hard drive disks and other miscellaneous mechanical devices.
• semiconductor wafer carriers such as H-bar wafer carriers, Front Opening Unified Pods (FOUPs), and Standard Mechanical Interface Pods (SMIFs)
• reticle carriers reticle carriers
• the semiconductor industry is in the process of evolving fabrication facilities to use wafers having a diameter of 300 mm.
• the wafer carriers used for 300 mm wafers are normally configured as a Front Opening Unified Pod (FOUP).
• FOUP wafer carriers are disclosed in U.S. Patent Nos. 6,082,540, 6,206,196, 6,216,874 and 6,267,245, each commonly owned by the assignee of the present invention, and each of which is fully incorporated herein by reference.
• Carrier materials should also have minimal outgassing of volatile components as these may leave films which also constitute a contaminant which can damage wafers and disks.
• the carrier materials must have adequate dimensional stability, that is rigidity, when the carrier is loaded. Dimensional stability is necessary to prevent damage to the wafers or disks and to minimize movement of the wafers or disks within the carrier.
• the tolerances of the slots holding wafers and disks are typically quite small and any deformation of the carrier can directly damage the highly brittle wafers or increase the abrasion and thus the particle generation when the wafers or disks are moved into, out of, or within the carrier.
• Polycarbonate material is extensively used for the enclosure portion of carriers, because of its transparency, ease of molding, and favorable abrasion resistance, heat resistance, chemical resistance, outgassing containment, rigidity characteristics, creep reduction, fluid absorption containment, UV protection, and other performance characteristics.
• polycarbonate is typically dramatically less expensive than other polymers that are suitable for use in carriers, such as polyetheretherketone (PEEK).
• Wafer carriers are often stored in multi-tier storage racks known as "stackers".
• stackers In a stocker, carriers are stored side-by-side in vertically stacked tiers. These stockers are typically arranged in opposing fashion across an aisle, from which they may be accessed by robotic equipment. Each stocker may be multi-floors high and may contain hundreds of carriers.
• vertical stacking offers an efficient means of storing many types of devices and materials, including wafer carriers, it is well known that stacked arrangements of flammable materials present a heightened fire protection concern. This is due to the general tendency of fire to propagate more readily vertically through buoyant motion of pyrolysis products.
• fixed fire sprinkler protection covering all areas of stacked material is often very difficult and expensive to achieve.
• one important fire protection strategy is to retard, or preferably even prevent, the vertical propagation of fire from material in one tier of storage to next tier that is immediately vertically adjacent. To the extent that propagation of a fire beyond the area of ignition can be slowed, more time is provided for detection and suppression of the fire in its incipient stages, thus minimizing damage and process disruption.
• Wafer carriers Two important variables that can have a significant effect on fire propagation in vertical storage are the geometry of the stored items and the flame propagation characteristics of the material composition of the items. In common fire protection engineering practice, these variables may sometimes be altered so as to obtain an optimal result from a fire protection standpoint. Wafer carriers, however, present a unique challenge in this regard in that the requirements of the semiconductor industry for wafer carriers are very stringent and process critical. For instance, in a wafer carrier, there may be over 200 precise dimensions required to hold wafers in place repeatably, and there are also stringent material standards for mechanical strength, structural integrity, and chemical stability of the materials used in the carrier as mentioned above. Any modifications made to carriers for the purposes of fire safety must not compromise these standards. Because of these difficulties, previous efforts to improve the fire safety of wafer carriers, both existing and new, have proceeded slowly and have not produced significant changes in wafer carrier design to date.
• the present invention substantially meets the needs of the industry for a relatively low cost carrier having performance characteristics sufficient to meet the needs of the semiconductor processing industry while also having significantly improved fire resistance charactistics. Further, the present invention meets the need for a wafer carrier that is resistant to the vertical propagation of fire, especially when multiple wafer carriers are stored in a vertical stocker arrangement. In addition, the present invention permits the use of less-expensive, more easily formable, polycarbonate plastic for the carrier, while still offering resistance to the vertical propagation of fire.
• a carrier includes an enclosure portion formed substantially from polycarbonate plastic.
• Selected portions of the enclosure have an outer surface portion formed substantially from a plastic material having a Fire Propagation Index of not greater than 9.0 (m/s 1/2 )(kW/m) "2/3 .
• Suitable plastic materials include polyimide, polyether imide, polyamide imide, polyketone, polyetherketone, polyetheretherketone, polyetherketoneketone, polyether sulphone, and polytetrafluoroethylene.
• An advantage of the invention is that a carrier enclosure may have significant portions formed from relatively low-cost, easily formable, transparent polycarbonate.
• Much higher cost fire resistive polymer materials may be selectively positioned on the enclosure where necessary to impact spread of fire on the carrier and to other adjacent carriers.
• Another advantage of the invention is that the fire retardancy of existing polycarbonate carriers may be improved.
• a carrier for articles includes an enclosure having an outer surface and an article support in the enclosure.
• the enclosure has a first portion formed substantially from polycarbonate plastic, and a second portion formed from a fire retardant plastic material having a flame propagation index of not greater than 9.0 (m/s 1 2 )(kW/m) "2/3 .
• the second portion forms at least a portion of the outer surface of the enclosure, whereby the outer surface portion is relatively retardant to vertical propagation of flame.
• the fire retardant plastic material may be selected from the group of plastic materials consisting of polyimide, polyether imide, polyamide imide, polyketone, polyetherketone, polyetheretherketone, polyetherketoneketone, polyether sulphone, and polytetrafluoroethylene.
• the invention may also include a wafer carrier having an enclosure portion formed substantially from polycarbonate plastic having at least a top, a bottom, a pair of opposing sides, a back, and an open front.
• the carrier further includes a door to close the open front, wherein the door has an outer surface portion formed substantially from a plastic material selected from the group of plastic materials consisting of polyimide, polyether imide, polyamide imide, polyketone, polyetherketone, polyetheretherketone, polyetherketoneketone, polyether sulphone, and polytetrafluoroethylene, and wherein the plastic material has a Fire Propagation Index of not greater than 9.0 (m/s )(kW/m) " '.
• FIG. 1 is an elevation view of a plurality of wafer carriers arrayed in stockers
• FIG. 2 is a perspective view of a wafer carrier
• FIG. 3 is an elevation view of a wafer carrier door according to a preferred embodiment of the present invention.
• FIG. 4 is a perspective, partially exploded view of a wafer carrier and door according to the present invention.
• FIG. 5 is a perspective, partially exploded view of an alternative embodiment of a carrier according to the invention.
• FIG. 5a is a cross-sectional view of one embodiment of the invention taken at section 5a-5a of Figure 5;
• FIG. 5b is a cross-sectional view of an alternative embodiment of the invention taken at section 5b-5b of Figure 5;
• FIG. 6 is a perspective view of a shipping box according to the invention.
• FIG. 1 depicts a plurality of FOUP wafer carriers 100 arrayed in typical vertical stockers 150.
• a typical semiconductor processing facility may have multiple rows of stockers 150 arranged in parallel fashion with aisles 180 between the rows as shown.
• Robotic handling equipment may be used in aisles 180 to transfer wafer carriers 100 to and from stockers 150.
• wafer carriers 100 are supported side-by-side by horizontal supports 160, forming vertically stacked tiers 162 of wafer carriers 100.
• Wafer carriers 100 are normally arranged in stockers 150 so that the door of the carrier faces outward into aisle 180.
• a typical FOUP wafer container 100 as used in the art has an enclosure portion 102, constructed of polycarbonate plastic, and having a top 104, a bottom 106, a pair of opposing sides 108 and 110, and a back 112.
• a door 114 closes the open front 116 of the enclosure portion 102, fitting into door recess 118.
• Wafer supports 122 are provided to support semi-conductor wafers within the enclosure.
• Kinematic coupling 124 mounted to the exterior surface of enclosure bottom 106 is provided to facilitate automated handling of the container during use and to provide a reference datum for locating the wafers in the housing during processing.
• Robotic lifting flange 126 is mounted on the exterior surface of enclosure top 104 and is provided to facilitate automated handling and transport of container 100 during use.
• vertical propagation of fire within stockers 150 may be retarded between tiers 162 at the sides 108, 110 and back 112 of wafer carriers 100 by providing solid portions in horizontal supports 160, blocking any vertical openings between tiers.
• doors 114 are vertically aligned, forming a pathway for vertical propagation of fire between tiers 162.
• AT g is the ignition temperature of the material above ambient in K°
• k is the material thermal conductivity in kW/m-K°
• p is the material density in g/m 3
• c p is the material specific heat in kJ/g-K°.
• Materials may be generally classified according to their FPI value. Materials having an FPI of under 7.0 (m/s 1 2 )(kW/m) "2 3 are classified as Group N-l "Non- Propagating" materials, those having an FPI of less than 10.0 (m s 1 2 )(kW/m) "2 3 but at least 7.0 (m/s )(kW/m) ⁇ are classified as Group D-l "Decelerating" materials, those having an FPI of between 10.0 (m/s 1 2 )(kW/m) "2/3 and 20.0 (m s 1/2 )(kW/m) "2/3 are Group 2 "Non- Accelerating Propagation” materials and those having an FPI of over 20.0 (m/s 1 2 )(kW/m) "2 3 are Group 3 "Accelerating Propagation" materials.
• Polycarbonate plastic as is commonly used for the enclosure and doors of wafer carriers, normally has a Fire Propagation Index (FPI) of greater than about 10.0 (m/s 1/2 )(kW/m) "2/3 , which classifies it as a Group 2 or Group 3 fire propagating material.
• FPI Fire Propagation Index
• at least the outer surface portion 130 of door 114 of each wafer carrier is formed substantially from a Group N-l or Group D-l fire retardant plastic material that has an FPI of 9.0 (m/s 1 2 )(kW/m) "2/3 or less.
• any fire retardant plastic material having an appropriate FPI may be suitable for the purpose
• plastics that are known to be acceptable for use in wafer carriers and that have the appropriate FPI are polyimide (PI), polyether imide (PEI), polyamide imide (PAI), polyketone (PK), polyetherketone (PEK), polyetheretherketone (PEEK), polyetherketoneketone (PEKK), polyether sulphone (PES), and polytetrafluoroethylene (PTFE).
• the currently most preferred material is PEI having an FPI from between about 8.1 (m/s 1 2 )(kW/m) "2 3 to about 8.6(m/s 1/2 )(kW/m) "2/3 , such as for example, Ultem 1000 made by GE Plastics, Inc. of Pittsfield, Massachusetts.
• At least outer surface portion 130 of door 114 is formed from PEI material. It is currently most preferred that the thickness of outer surface portion 130 formed from the fire retardant plastic material be at least the typical thickness of enclosure portion 102, which is generally about 0.3 mm. It is currently most preferred that outer surface portion 130 is the exterior panel 132 of door 114 alone as shown in FIG. 2, but may also be a separate fire-retardant layer 134 laid over exterior panel 132 of door 114 as shown in FIG. 3. Such a fire retardant layer 134 may be overmolded on exterior panel 132, forming a thermal as well as a mechanical bond with exterior panel 132, or may be a separate shield panel 136 as shown in FIG. 4, attached by any suitable method, including adhesives or mechanical fasteners. As an alternative, shield panel 136 may have structures allowing it to removably "snap" on and off suitable receiving structures on door 114.
• the outer fire resistant layer can be a thin film that has been insert molded on the forward facing surface of the front door.
• a suitable method of film insert molding is disclosed in U.S. Patent Application Serial Number 10/304,775, entitled “SEMICONDUCTOR COMPONENT HANDLING DEVICE HAVING A PERFORMANCE FILM", commonly owned by the owners of the present invention and hereby fully incorporated herein by reference.
• Co-pending U.S. Patent Application 09/317,989 owned by the present applicant discloses the use of overmolding to manufacture carriers and components and is also herein incorporated by reference.
• Other portions of door 114, such as the chassis 140, latching components, and inner surface 142 may also be formed from the same fire retardant material used for outer surface portion 130, and this may serve to improve the overall fire retardancy of wafer carrier 100.
• Existing wafer carriers with polycarbonate outer surfaces may be retrofitted using the apparatus and methods of the present invention. Such a retrofit may be accomplished in the case of a FOUP by replacing the polycarbonate door with a door 114 manufactured according to the present invention, or by overlaying exterior panel 132 with shield panel 136 as described above. Such a shield panel may be a flexible sheet material suitably adhered to existing door structure. It will be appreciated that the materials and methods of the present invention could be applied to other surfaces on a FOUP and to any other type of carrier.
• a SMIF pod carrier 200 has a base portion 202 and a cover portion 220, with sides 222, front 224, and back 228.
• Cover portion 220 engages base portion 202 at recessed region 282, with the bottom periphery of cover portion 220 fitting aroung and covering periphery 280 of base 202.
• a article support in the form of H-bar wafer carrier 260 having wafer shelves 262 is engaged with base 202 inside the enclosure.
• selected portions 230 of the outer surface 232 of cover portion 220 may be made from a polymer material having an FPI of 9.0 (m/s 1/2 )(kW/m) "2 3 or less.
• cover portion 220 may be entirely formed from the fire resistant material as depicted in Figure 5a.
• a first portion 234 of the enclosure is formed from polycarbonate
• a second portion 236 is formed from the fire retardant polymer material.
• the first and second portions may be molded together using conventional molding techniques.
• a layer of the fire resistant material 238 may be applied at selected portions 230 over a layer 240 of lower cost polymer such as polycarbonate as depicted in Figure 5b, by any suitable method, such as film insert molding, overmolding, or welding as described above. Again, it is anticipated that layer 238 should be at least about 0.3 mm in thickness for best fire retardancy results.
• separate shield panels may be affixed over a polycarbonate cover portion 220 by welding, fasteners, or adhesive as described above.
• cover portion 302 may have selected portions 304 of the outer surface 306 made from a polymer material having an FPI of 9.0 (m/s 1 2 )(kW/m) "2/3 or less. Again at selected portions 304, cover portion 302 may be entirely formed from the fire resistant material or a layer of the fire resistant material may be applied over a layer of lower cost polymer such as polycarbonate by film insert molding, overmolding, or welding as described above. It is anticipated that it may be especially advantageous to form overhanging lip portions 310 from fire retardant plastic material.
• Hot pyrolysis products from a burning base portion 312 of the container 300 will be deflected outward by overhanging lip portions 310, away from vertical surfaces 314, thereby inhibiting vertical propagation of fire.
• cover portion 302 may settle downward, tending to suppress the fire underneath.

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• Engineering & Computer Science (AREA)
• Physics & Mathematics (AREA)
• Condensed Matter Physics & Semiconductors (AREA)
• General Physics & Mathematics (AREA)
• Manufacturing & Machinery (AREA)
• Computer Hardware Design (AREA)
• Microelectronics & Electronic Packaging (AREA)
• Power Engineering (AREA)
• Packaging Frangible Articles (AREA)
• Container, Conveyance, Adherence, Positioning, Of Wafer (AREA)

Applications Claiming Priority (5)

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• 2003
  • 2003-07-04 TW TW92118305A patent/TW200403796A/zh unknown
  • 2003-07-07 EP EP03763268A patent/EP1539614A1/en not_active Withdrawn
  • 2003-07-07 AU AU2003249731A patent/AU2003249731A1/en not_active Abandoned
  • 2003-07-07 WO PCT/US2003/021161 patent/WO2004005163A1/en active Application Filing
  • 2003-07-07 CN CN 03821230 patent/CN1681723A/zh active Pending
  • 2003-07-07 JP JP2004519941A patent/JP2006505921A/ja active Pending

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