Wafer shipper with orientation control

An injection molded container for storing and transporting wafers includes a base having a wafer area upon which to place a stack of a plurality of wafer assemblies, wherein each wafer assembly includes a wafer frame upon which is mounted a wafer. A protective wall apparatus is positioned around the wafer area, and includes at least one wall contour artifact. Each wafer frame according to the invention includes a corresponding opposite/mating artifact. The wall apparatus and wafer frame are configured so that the wafer frame must be oriented to mate the wall and frame artifacts in order for the wafer frame to be installed in the container.

This application is related to U.S. patent application Ser. No. 10/623131 entitled “Wafer Storage Container With Wafer Positioning Posts”.

BACKGROUND OF THE INVENTION

Field of the Invention

The present invention is related generally to containers for storage and shipment of wafers, and more particularly to a container for use with wafer frames upon which wafers are mounted wherein the container is configured to assure a single orientation of wafer frames when placed in the container.

Description of the Prior Art

Semiconductor wafer storage and shipping containers are generally designed for ease of access and/or wafer safety. U.S. Pat. No. 4,043,451 by Johnson describes a shipping container for semiconductor wafers in the form of an elongated enclosure and lid, with interior ribs for locating the wafers lined with resilient curved wafer support material. Rotational positioning of the wafers is not addressed. A container with similar features is disclosed in U.S. Pat. No. 6,499,602 B2 by Yajima et al., providing a slot for each wafer, but not addressing wafer rotational positioning. U.S. Pat. No. 6,550,619 B2 by Bores et al. discloses a container for stacked wafers with improved resistance to shock. U.S. Pat. No. 6,218,727 B 1 by Merkl et al. discloses a container, and describes a wafer frame. The container has parallel slots on either of two interior opposing walls for holding a wafer frame with linear sections on opposite edges for achieving support when placed in the container slots.

SUMMARY

An advantage of this invention is that provides for an automatic alignment of wafers in a wafer container.

A further advantage of this invention is that in providing alignment of wafers in a storage container, it reduces the degree of effort required in procedures requiring transferring of wafers from a container and into an aligned position for processing.

In one embodiment of the present invention, an injection molded container for storing and transporting wafers includes a base having a wafer area upon which to place a stack of wafer assemblies, wherein each wafer assembly includes a wafer frame and an attached wafer. A protective wall apparatus is positioned around the wafer area, and includes at least one wall wafer orientation artifact. Each wafer frame according to the invention includes a corresponding opposite/mating artifact. The wall apparatus and wafer frame are configured so that the wafer frame must be oriented to mate the wall and frame artifacts in order for the wafer frame to be installed in the container.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

While the present invention will be described herein with reference to particular embodiments thereof, a latitude of modifications, various changes and substitutions are intended, and it will be appreciated that in some instances some features of the invention will be employed without a corresponding use of other features without departing from the spirit and scope of the invention as described with respect to the preferred embodiments set forth herein.

The concept of the present invention is illustrated inFIG. 1Awhich is a simplified drawing for use in describing the invention. A container10has a protective wall apparatus12extending upward from a base14, and includes at least one wafer orientation artifact16which can be either a protrusion16as shown or a recess, or other apparatus for an engagement with a corresponding opposite mating alignment artifact18, which is an artifact in a wafer element which can be a wafer frame20as shown, or it can be an artifact in a wafer, in either case for determining the position orientation of the wafer element (wafer or wafer frame) in the container10. In this case where a wafer frame20is used, a wafer22can be secured to each of the frames20, and the orientation artifact16and alignment artifact18can therefore be used to determine the orientation of the wafer22when the wafer22is placed in the wafer frame with a known orientation relative to the artifact18. A wafer and frame, or just a wafer without a frame will be referred to generally/generically as a wafer element. The wall apparatus12can be of any configuration for providing protection to the wafers22in the container10. The wall can be continuous, as shown, or it can be a plurality of sections.

FIG. 1Bis a cross sectional view A—A of a wafer element23that includes a wafer frame20and a wafer. The wafer frame is in the general shape of a ring with a hole25there-thru into which is placed a wafer22.FIG. 1Bis presented in order to describe a method of attaching a wafer22to a frame20. The attachment as shown inFIG. 1Bis accomplished using an adhesive film25, placed with an adhesive surface in contact with a bottom surface of the frame20, as well as with a bottom surface of the wafer22. The use of tape25is well understood by those skilled in the art for the purpose of securing a wafer22within a frame20. The tape25generally covers substantially all of the bottom surface of the frame, as well as the entire bottom surface of the wafer. The tape normally used has a characteristic (example blue color) that it does not absorb laser energy used to cut a wafer. In some applications, the tape is applied to the frame, then a wafer is placed in the hole25on the adhesive of the tape. If the wafer is to be diced, a laser is then used to cut the wafer into separate parts. The tape remains undisturbed by the cutting of the wafer. A typical thickness of the wafer frame is 0.030 inches.

In one embodiment of the present invention the container is formed by an injection molding process. In this case, the walls would generally include a draft angle. This is described below and illustrated in reference toFIGS. 2A and 2B.

FIG. 2Ashows an alternate embodiment of a container24wherein the wall apparatus includes a draft angle, simply illustrated as angle26of the interior surface and angle27of the exterior surface of wall28. Lines30and31represent lines orthogonal to a plane, referred to as a wafer area32, upon which the stack of wafer elements are placed. The use of a draft angle26is in conformance with standard practice in injection molding, and is often a small angle in the range of 1–5 degrees. This method of construction applies as one embodiment of the container of the present invention. The draft angle is generally required in order for a product to be easily separated from a mold. A container that has walls with a draft angle has an interior width that is wider at the top than at the bottom of the container. As a result of the interior wall37having a draft angle, the distance between a wafer element i.e., a wafer, or wafer frame if a frame is used, and the wall increases in proportion to the distance of the wafer element from the wafer area32. This increased spacing in prior art containers allows more movement of the wafer elements, and is undesirable.FIG. 2Bis a cross sectional view B—B that more clearly shows the draft angles26and27of the interior and exterior walls respectively.

FIG. 2Aserves to illustrate an alternate embodiment of the present invention for solving the problem of the increased spacing with increased wafer element distance from the wafer area when the wall has a draft angle. Columns36are placed around the wafer area32providing a vertical line of contact for restricting movement of wafer elements in the container that would otherwise occur due to the draft angle causing a larger distance between the wall28and wafer elements as described above. A dashed-line38is used inFIG. 2Aon one of the columns36to illustrate a surface line of contact on the column for restricting movement of all of the wafer elements in a stack equally from the bottom of the stack to the top of the stack. The columns can be of various configurations of any structure that provides a vertical line of contact, and can for example be integrally molded with the wall structure. The wall28can be a continuous wall, or a plurality of wall sections of various possible configurations. Although the vertical line of contact does not have a draft angle, the resulting vertical area is very small, i.e. insubstantial compared to the total wall area, and as a result the vertical portion does not cause sufficient resistance to defeat removal of the container from the mold.

FIG. 3shows a container40designed according to the present invention and a container cover42. The wall apparatus44of container40has four sections,46,48,50and52. According to the present invention, specific irregular contours that will be referred to as orientation artifacts are integrally formed with walls of this embodiment and mate with corresponding alignment artifacts in the wafer elements to be placed in the container. The particular embodiment as shown inFIGS. 3,4and5is for use with a wafer element that includes a frame with a wafer (whole or diced). The present invention also applies to wafer elements including only a wafer with at least one artifact. In this latter case, the container would be configured to conform to the wafer which would generally be round, with at least one artifact. Referring now to the specific embodiment, the artifacts, as will be described assure that all of the wafer elements, each including a wafer frame and a wafer in this particular embodiment, are oriented the same in the container40, therefore making it possible for all of the wafers to be in known orientations, assuming that they are oriented relative to the wafer frame alignment artifact.

As shown inFIG. 3, the artifacts that assure only one orientation for a wafer frame, are portions54and56.FIG. 3also shows four prongs58for insertion through slot60in the cover42for holding the cover42onto the container40.

FIG. 4Ashows a stack62of wafer elements, including frames64with wafers66attached. Each wafer frame64has an alignment artifact68for mating with an orientation artifact54of container40, and an alignment artifact70for mating with a corresponding container mating orientation artifact56. The stack62of wafer elements ofFIG. 4A, and generally for any stack, will include some form of separators between each wafer element. The separators may be for example thin disks constructed of paper or foam, and/or a carbon/carbon impregnated material. Such an arrangement using all of the above is illustrated inFIG. 4B, wherein a container90has a wafer element92placed therein, with a carbon interleaf94, a foam interleaf96, and a paper interleaf98in position for placement on top of the wafer element92. A cover100is also shown.

FIG. 5is a top view of the container40ofFIGS. 3 and 4A, and illustrates more clearly various features of the present invention. An outline71of a frame, such as frame64ofFIG. 4, is shown in the container40. Frame contour artifacts68and70are shown mated with the wall structure/apparatus contour artifacts54and56respectively. It should be noted that only one of the container orientation artifacts54or56and corresponding wafer frame alignment artifacts68or70are needed in order to assure only one orientation possible for a frame in the container. Alternatively, if the wall sections46,48,50and52conform to a common circle, then a single irregularity/artifact would need to be asymmetrical, i.e., lacking in symmetry in order to assure that a frame could not be inserted upside down. The particular wall sections46,48,50and52, as shown each have flat surfaces which by themselves would force orientation of the frame to be in one of four positions. For example, flat surfaces72and74of the wall structure conform to a flat portion76of the frame. In such a configuration, it is still necessary for there to be at least one artifact such as54or56placed asymmetrically, in order to assure only one orientation of the frame in the container, and to assure that the frame could not be installed upside down. Various configurations for accomplishing the objective of the present invention as disclosed will be apparent to those skilled in the art, and these are to be included in the spirit of the present invention.

According to an alternate embodiment, as described above the container can also include walls with a draft angle, and with columns for restricting movement of the wafer assemblies.FIG. 5also illustrates these alternate embodiments, including 16 columns78shown as structures that are integrally molded with the wall sections46–52. The columns78all have a surface designed to provide a vertical line of contact, i.e., orthogonal to the plane of the wafer area80for restraining lateral movement of the wafer assemblies over the entire stack height. The lines of contact have a vertical orientation extending upward at a right angle relative to the plane of the wafer area80upon which a stack of wafer assemblies are to be placed. Because the columns78inFIG. 3are integrally molded with the wall sections, and due to the vertical/orthogonal direction of the lines of contact i.e. no draft angle on the line of contact, the columns78appear wider in the view ofFIG. 5near the top of the wall structures than at the bottom of the wall at the base80level. The top surfaces82of each column provide a substantial point of contact for pressuring the container for removal from a mold.

The draft angle of the wall sections46,48,50and52is evident by the line84indicating the inside perimeter of the wall section at the level of the bottom of the wall sections. Line86indicates the inner perimeter of the wall section at the top of the wall, which clearly lies outside the line84, therefore indicating the draft angle. This detail is more clearly shown in the enlargened section A

Section A also shows columns78more clearly. Note that the top view ofFIG. 5shows only a single line88passing across the line of contact i.e. the vertical line which would contact a wafer or wafer frame. The single line88indicates that the line of contact is perpendicular to the base80, and therefore the line of contact does not show in the top view ofFIG. 5. In contrast, the two lines84and86indicate the draft angle of the wall sections46,48,50,52.

While the present invention has been described herein with reference to particular embodiments thereof, a latitude of modifications, various changes and substitutions are intended in the foregoing disclosure, and it will be appreciated that in some instances some features of the invention will be employed without a corresponding use of other features without departing from the spirit and scope of the invention as set forth in the appended claims.