The present invention relates generally to film insert molding, and more particularly to insert molding a thin protective containment polymer film during the molding of semiconductor component handlers or carriers.
Conventional film insert molding techniques are generally utilized in manufacturing processes to increase aesthetic appeal in various consumer products. Namely, decorative decals, instructions, logos, and other visual graphics are printed on one surface of a thin transparent polymer film for use in the insert molding process. Later developments expanded the use of the film to permanently fix functional features such as barcodes to the products. In both circumstances, the film is placed into a portion of the mold prior to the injection of the moldable material. This creates a bond between the film and the molded part such that inexpensive decoration or indicia can be selectively placed on the part, while at the same time simplifying the use of indicia around complicated contours and in difficult-to-reach locations. Similarly, such film insert molding or decorative molding simplifies the manufacturing process by eliminating the need to have the indicia etched or shaped into the actual surface of the mold itself. This increases design and manufacturing flexibility, and the level of detail that can be included in the final product.
The semiconductor industry introduces unique and unconventional purity and anti-contamination requirements into the development and implementation of product designs and manufacturing processes. Most importantly, material selection is essential in the manufacturing, storage, and transportation of components and assemblies. For instance, various polymer materials such as polyethylene (PE), polycarbonates (PC), perflueroalkoxy (PFA), polyetheretherketone (PEEK), and the like are generally utilized in the manufacturing of components and structures incorporated in constructing wafer carriers and chip trays.
Wafer Carriers
The processing of wafer disks into integrated circuit chips often involves several steps where the disks are repeatedly processed, stored and transported. Due to the delicate nature of the disks and their extreme value, it is vital that they are properly protected throughout this procedure. One purpose of a wafer carrier is to provide this protection. Additionally, since the processing of wafer disks is generally automated, it is necessary for disks to be precisely positioned relative to the processing equipment for the robotic removal and insertion of the wafers. A second purpose of a wafer carrier is to securely hold the wafer disks during transport.
Carriers are generally configured to axially arrange the wafers or disks in 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. There are a number of material characteristics which are useful and advantageous for wafer carriers depending on the type of carrier and the particular part of the carrier at issue.
During processing of semiconductor wafers or magnetic disks, the presence or generation of particulates presents very significant contamination problems. Contamination is accepted as the single largest cause of yield loss in the semiconductor industry. As the size of integrated circuitry has continued to be reduced, the size of particles which can contaminate an integrated circuit has also become smaller, making minimization of contaminants all the more critical. Contaminants in the form of particles may be generated by abrasion such as the rubbing or scraping of the carrier with the wafers or disks, with the carrier covers or enclosures, with storage racks, with other carriers, or with the processing equipment. A most desirable characteristic of a carrier is therefore a resistance to particle generation upon abrasion, rubbing, or scraping of the plastic molded material. U.S. Pat. No. 5,780,127 discusses various characteristics of plastics which are pertinent to the suitability of such materials for wafer carriers, and is 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. Dimensional stability is also extremely important when the carrier is loaded in some direction such as when the carriers are stacked during shipment or when the carriers integrate with processing equipment. The carrier material should also maintain its integrity under elevated temperatures which may be encountered during storage or cleaning.
Visibility of wafers within closed containers is highly desirable and may be required by end users. Transparent plastics suitable for such containers, such as polycarbonates, are desirable in that such plastic is low in cost but such plastics may not have sufficient performance characteristics such as abrasion resistance, heat resistance, chemical resistance, outgassing containment, rigidity characteristics, creep reduction, fluid absorption containment, UV protection, and the like.
Other important considerations include the cost of the carrier material and the ease of molding the material. Carriers are typically formed of injection molded plastics such as PC, acrylonitrile butadiene styrene (ABS), polypropylene (PP), PE, PFA, PEEK, and like materials.
One major benefit of particular specialized polymers is their abrasion-resistant qualities. Typical inexpensive conventional plastics release tiny particles into the air when abraded or even when rubbed against other material or objects. While these particles are typically invisible to the naked eye, they result in the introduction of potentially damaging contaminants that may adhere to semiconductor components being processed, and into the necessarily controlled environments. However, specialized thermoplastic polymers are dramatically more expensive than conventional polymers. In fact, the various specialized thermoplastic polymers themselves can vary greatly—i.e., PEEK is more expensive than PC.
Conventional practices include constructing an entire wafer carrier/handler component of a material to obtain any one of the listed performance characteristics. As stated, however, the manufacturing and use of materials such as PEEK is dramatically more expensive and it is often undesirable and even infeasible to utilize the material in the construction of large handler components. Additionally, PEEK can be difficult to manipulate and mold in the manner required in manufacturing such semiconductor handlers. Currently, a manufacturer of wafer carriers is forced to make a decision between the benefits of functional performance characteristics of a particular thermoplastic, and the cost to manufacture all, or a substantial portion, of the product out of the material. While functional thermoplastic materials may only be needed in particular applications on particular part or component surfaces of the carrier that touch delicate semiconductor components or processing equipment, the entire section or part of the handler is typically constructed of the functional polymer. As stated, this is inefficient in terms of both cost and manufacturing integrity.
As a result, there is a need in the semiconductor industry for manufacturing techniques that substantially reduce unnecessary manufacturing processes and permit targeted and localized implementation of functional thermoplastic materials to provide enhanced performance characteristics at the targeted handler surface. Such an innovation would significantly reduce the costs of manufacturing and design by permitting selective use of desirable, but often expensive, thermoplastics polymers.
The present invention relates generally to a system and method for including a thin protective containment thermopolymer film in the molding process for handlers, transporters, carriers, trays and like devices utilized in the semiconductor processing industry. The thermoplastic film of predetermined size and shape is selectively placed along a shaping surface in a mold cavity for alignment with a desired target surface of a moldable material. The molding process causes a surface of the film to bond to a contact surface of the moldable material such that the film is permanently adhered to the moldable material. As a result, a compatible polymer film can be selectively bonded only to those target surfaces where performance characteristics such as abrasion resistance, heat resistance, chemical resistance, outgassing containment, rigidity enhancement, hardness, creep reduction, fluid absorption containment, and the like is needed. For instance, semiconductor wafer carrier support structures can include such a polymer film along at least a portion to provide an abrasion resistance contact surface for receivably securable wafers. Further, the protective containment film can include addition film layers to comprise a film laminate for bonding to the semiconductor component handling devices, and to add polymer layers having different functional performance characteristics.
An object and feature of particular embodiments of the present invention is that it provides a cost-efficient method of selectively utilizing desirable polymers, and the polymers' corresponding functional characteristic, wherein it is not necessary to utilize more of the polymer than is required.
Another object and feature of particular embodiments of the present invention is that a functional thermoplastic film can be selectively bonded to a portion of a wafer carrier, chip tray, or other semiconductor component handler or transporter that contacts sensitive parts, components, or processing equipment.
A further object and feature of particular embodiments of the present invention is the selective use of preferred abrasion-resistant polymer films on parts being used in the semiconductor processing industry.
Still another object and feature of particular embodiments of the present invention is forming a semiconductor component handling device with a polymer filmed surface area that is transparent or translucent while still providing functional performance advancements for the selected surface. Such a handling device is formed by utilizing a thin enough layer of a material on a selected target structure of the device, and overmolding the structure, with or without an intermediate layer, to the substantially transparent or translucent device body constructed of a material such as PC.
Referring to
Protective/Containment Film
The at least one protective or containment film 10 is a thermoplastic polymer having a functional performance characteristic. Functional performance characteristics can include abrasion resistance, heat resistance, chemical resistance, outgassing containment, fluid absorption containment, UV protection, and the like concerns known to be considered in the field of semiconductor processing. Additional functional performance characteristics can include rigidity characteristics, creep reduction, hardness, and a myriad of other dimensionally stabilizing characteristics. The film 10 is at least partially defined by a limited thickness. For instance, a single film layer thickness equal to or less than approximately 0.040 inches (forty thousandths) is envisioned. Preferably, the single film layer is less than or equal to approximately 0.030 inches (thirty thousandths). Of course, the implementation of laminates of multiple layers will alter this preferred thickness criteria. Any compatible material can be utilized for the film 10 to achieve these functional performance characteristics. For example, polyester, polyimide (PI), polyether imide (PEI), PEEK, perfluoroalkoxy resin (PFA), fluorinated ethylene propylene copolymer (FEP), polyvinylidene fluoride (PVDF), polymethyl methacrylate (PMMA), polyether sulfone (PES), polystyrene (PS), polyphenylene sulfide (PPS), and a myriad of other compatible polymers are available. To employ the performance enhancing film 10 in manufacturing of semiconductor component handling devices 12, the film 10 is generally cut to a predetermined shape and size depending on the particular needs of the bonding application. After cutting, the film 10 can then be thermoformed. The film 10 is generally thin and sheet-like to better facilitate moldability and to capitalize on the transparent or translucent characteristics of the material. Co-pending U.S. application Ser. No. ______, owned by the present Applicant and entitled “SEMICONDUCTOR COMPONENT HANDLING DEVICE HAVING AN ELECTROSTATIC DISSIPATING FILM” is incorporated herein by reference in its entirety.
In addition to insert molding a single film 10, a plurality of films 10 can be laminated to comprise a composite film structure for moldable bonding to the semiconductor component handling devices 12. For instance, various film layers can include differing performance or containment characteristics listed herein, or to provide a combination thereof. A myriad of film lamination techniques known to one skilled in the film lamination art are envisioned for use with the present invention. For instance, U.S. Pat. Nos. 3,660,200, 4,605,591, 5,194,327, 5,344,703, and 5,811,197 disclose thermoplastic lamination techniques and are incorporated herein by reference.
Performance Film Insert Molding
Referring primarily to
In one embodiment, the cover portion 24 is removably securable to the mold cavity 22 to facilitate film 10 insertion, and removal of the finished handling device portion or part 32. The molded part 32 is generally something less than a completed handling device 12. For example, it is common for sidewall inserts and shelves of wafer carriers to be separately molded, and often to be molded of dissimilar plastics in comparison to the main body of the carrier. Various injection and insert molding techniques are commonly known to those skilled in the art and can be implemented without deviating from the spirit or scope of the present invention.
The moldable material 30 is preferably a substantially non-conductive thermoplastic material commonly used in molding parts for any handling device used in the semiconductor processing industry. Again, the material 30 can be PFA, PE, PC, and like known materials. More specifically, the moldable material 30 can be the material conventionally used to construct wafer carriers, chip trays, and components and parts thereof.
In operation, the performance film 10 is generally cut to a predetermined shape and then thermoformed to a required form. The thermoformed film 10 is placed into the molding unit 20 such that the film 10 is in surface contact with at least a portion of the at least one shaping surface 26 of the mold cavity 22. As indicated herein, various techniques such as vacuum, static, and forceable securement can be implemented to facilitate proper positioning of the film 10 to the cavity 22 or the shaping surface 26. The cover portion 24 may then be closed in preparation for injection of the material 30. At this stage of the process, the moldable material 30 is injected in a substantially molten state into the cavity through the at least one injection channel 28. After waiting a requisite cooling period, the moldable material 30 within the molding unit 20 cools to form the substantially solidified molded part 32. The molten injection combined with the cooling process forms a permanent adhering bond between the at least one film 10 and the molded part 32.
After completion of the molding process, the molded part 32 can be ejected from the molding unit 32 with the part 32 having a performance enhancing film 10 permanently bonded to a selective target surface. Conventional tooling, techniques, and practices known by those skilled in the art can be used in injecting the material 30 and ejecting the part 32.
Wafer Handler/Carrier
Various conventional wafer handling devices 34 and device 34 components or parts are shown in
U.S. Pat. Nos. 6,428,729 6,039,186, 5,485,094, and 5,944,194, and disclose particular configurations and processes for constructing wafer handling devices 34, and are incorporated herein by reference. In one embodiment the wafer handler 34 includes at least a body portion 38, and a support structure 40 having a plurality of axial support shelves 42 capable of receivably supporting the wafers or disks by, or near, their peripheral edges. The wafers or disks are conventionally removable from the carriers 34, at the shelves 42, in a radial direction upwardly or laterally. The shelves 42 serve as the primary point of contact between the wafers and the carrier 34. As a result, one embodiment of the present invention includes insert molding a protective film 10 to at least a portion of this support structure 40 and/or the supporting shelves 42. The protective film 10 can be selectively placed within the mold cavity 22 of the molding unit 20 such that it covers an entire surface or side of the molded part, wherein the molded part 32 is the support 40, the support shelves 42, a limited predefined portion of the shelves 42, or various other combinations. Further, the film 10 can be specifically bonded for alignment with other adjacent and abuttable components of the wafer handler 23 to provide for extended protection. By advancing selective bondable placement of the film 10 to nearly any surface or component surface of the wafer handler 34 to introduce or increase abrasion resistance, heat resistance, chemical resistance, outgassing containment, UV protection, rigidity characteristics, creep reduction, hardness, fluid absorption containment, and the like
In other embodiments of the present invention, the wafer handler 34 can include flanges 44 (
In certain instances, the insert molded performance film 10 may not adhere sufficiently to other polymers. For example, PEEK (i.e., film 10) does not adhere in all cases to overmolded PC (i.e., wafer handler 34 components such as the body 38). Referring to
With such selective bonding of the at least one performance or functional film 10, selective use of specific materials at specific target surface and handler components is possible. This selective targeting promotes manufacturing and costs efficiencies as the desired or even required film 10 material may be quite different than what is needed in the construction of the remainder of the wafer carrier 34, or even the specific part 32.
Chip Handler/Tray
In another embodiment, the handling device 12 is a chip tray 36 including a plurality of seating recesses 50 or recess assemblies adapted to secure a plurality of chips, and peripheral side walls 52, as shown in
One embodiment of the present invention includes insert molding the performance film 10 to a selected portion or surface of the chip tray 36, such as the seating recesses 50. Other embodiments can include insert molding the film 10 to the entire top surface of the tray 36 including the recesses 50, the side walls 52, and combinations thereof. For instance, the film 10 can be selectively bonded to portions of the side walls 52 to enhance abrasion resistance from contact or engagement with processing equipment or automated machinery and robotics.
Further, the peripheral side walls 52 of the chip trays 36 are generally shaped for stackable engagement with other chip trays 36. Stacking posts/members and/or peripheral wall ledges on the bottom portion of the trays 36 can be sized and shaped for alignment with corresponding grooves or lips on the top surfaces of the trays 36. Other stacking techniques and tray designs known to one skilled in the art are also envisioned for implementation with the present invention. To provide a layer of protection, film 10 can be molded to the stackable engagement regions of the peripheral side walls 52.
As with the wafer handlers 34, selective bonding of the at least one protective performance film 10 to selected target surfaces of the chip tray 36 provides a preferred employment of performance enhancing thermoplastics while still allowing a manufacturer to construct the remaining portions of the tray 36 of other preferred polymers.
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.
The present invention claims priority to Provisional Application No. 60/333,689, filed Nov. 27, 2001, entitled PERFORMANCE POLYMER FILM INSERT MOLDING FOR WAFER CARRIERS and is incorporated herein by reference.
Filing Document | Filing Date | Country | Kind | 371c Date |
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PCT/US02/37860 | 11/26/2002 | WO | 6/1/2005 |
Number | Date | Country | |
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60333689 | Nov 2001 | US |