US20030234208A1

US20030234208A1 - Container with magnifying identification lens

Info

Publication number: US20030234208A1
Application number: US10/175,611
Authority: US
Inventors: Hsin-Chieh Huang
Original assignee: Taiwan Semiconductor Manufacturing Co TSMC Ltd
Current assignee: Taiwan Semiconductor Manufacturing Co TSMC Ltd
Priority date: 2002-06-20
Filing date: 2002-06-20
Publication date: 2003-12-25

Abstract

A wafer pod or container fitted with at least one magnifying lens for magnifying the size of a lot number or other identifying indicia typically inscribed on a wafer inside the pod or container. The magnifying lens enables quick and accurate visual identification of the wafers by lot number or other identifying indicia as the wafers are transported in a semiconductor wafer fabrication facility.

Description

FIELD OF THE INVENTION

The present invention relates to containers used in the storage and transport of semiconductor wafers in a semiconductor fabrication facility. More particularly, the present invention relates to a wafer container fitted with a magnifying lens or lenses to facilitate quick and accurate identification of wafers in the container.

BACKGROUND OF THE INVENTION

A standardized mechanical interface (SMIF) system is disclosed in U.S. Pat. Nos. 4,532,970 and 4,534,389. Such a SMIF system is designed to reduce particle fluxes onto semiconductor wafers and/or reticles in a semiconductor production facility. The SMIF system prevents or minimizes particle contamination of the wafers during transport and storage of the wafers by ensuring that gaseous media surrounding the wafers is essentially stationary relative to the wafers, and further, by preventing exposure of the wafers to particles from the ambient environment.

The SMIF concept is based on the use of a small volume of motion- and contamination-controlled, particle-free gas to provide a clean environment for semiconductor wafers and other articles. Further details of one such system are described in a paper entitled, “SMIF: A TECHNOLOGY FOR WAFER CASSETTE TRANSFER IN VLSI MANUFACTURING”, by Mihir Parikh and Ulrich Kaempf, Solid State Technology, July 1984, pp. 111-115.

SMIF systems are designed to prevent contamination by particles which range from below 0.02 μm to above 200 μm. Due to the small geometries of the components in modern semiconductor integrated circuits, particles falling within this size range can significantly adversely affect semiconductor processing. Current geometry sizes for semiconductor integrated circuits have reached less than half a micron, and those circuits are adversely affected by particles having a size as small as 0.01 μm. In the future, semiconductor integrated circuits will be marked by increasingly smaller geometry sizes, requiring protection from contamination by correspondingly smaller particles.

In a typical SMIF system, semiconductor wafers are stored and transported in wafer cassette containers, or pods, and are transferred from the pod to processing or testing equipment typically in the following manner. First, the pod is placed at the interface port of a processing tool. Each pod includes a box and a box door designed to mate with doors on the interface ports of the processing equipment enclosures. Then, latches release the box door, and the box door and the interface port door are opened simultaneously such that particles which may have adhered to the external door surfaces are trapped or sandwiches between the box and interface port doors. A mechanical elevator lowers or translates the two doors, with the cassette riding on top, into the enclosure-covered space. The cassette is transferred by gravity or a manipulator and placed onto the cassette platform of the equipment. After processing, the reverse operation takes place.

FIG. 1 illustrates a typical

conventional SMIF pod

10 used in conjunction with a port assembly 12 on a canopy of a semiconductor processing tool or station (not illustrated). The SMIF pod 10 includes a pod cover 14 having multiple cover sides 16, a flanged cover base 20 and a cover top 22. When removably attached to the cover base 20 of the pod cover 14, a pod door 18 of the SMIF pod 10 supports a wafer cassette 24 (FIG. 2) holding multiple semiconductor wafers 1 inside the pod cover 14. The SMIF pod 10 is used to transport the wafers 1 such as from one processing or testing tool or station to another in the semiconductor production facility, typically by the use of overhead transport vehicles (OHTs) or automatic guided vehicles (AGVs).

After it arrives at the appropriate processing tool or station in the facility, the SMIF

pod

10 is initially placed on a port door 28 of the port assembly 12. An elevator assembly (not illustrated) then lowers the port door 28, which lowers the pod door 18 and the wafer cassette 24 supported on the pod door 18 from the interior of the pod cover 14, through a port plate 26 of the port assembly 12 and into a minienvironment (not illustrated) beneath the canopy of the processing tool. After processing of the wafers 1, the port door 28 is actuated by the elevator to lift the pod door 18 and wafer cassette 24 upwardly through the port plate 26, at which time the pod door 18 is re-attached to the cover base 20 of the pod cover 14 with the wafer cassette 24 and wafers 1 sealed in the reassembled SMIF pod 10.

During processing of semiconductor wafers at the various processing tools or stations, groups or “lots” of wafers are manufactured together in batches. Each wafer within a lot is processed at the same time and under the same conditions as all the other wafers in the lot. Each wafer lot is assigned a serial number, or “lot number”, and within each lot, each wafer is assigned a unique serial number.

For a number of reasons including quality control, wafer manufacturers find it useful to track wafer lots as they travel from one station or tool to another in the facility. A reliable method of identifying the wafers by lot number is therefore very important for accurate tracking of the wafers. To properly identify the wafers by lot throughout the fabrication process, identification marks must be placed on each wafer. Because all of the wafers in a SMIF pod are in the same lot, the pod cover is typically constructed of a clear or transparent material to facilitate visual lot identification of the wafers therein by facility personnel without requiring removal of the pod cover from the pod door.

FIG. 2 illustrates a wafer 1 supported by a wafer cassette 24 inside a SMIF pod 10. The wafer 1 is visible through the clear or transparent cover top 22 of the pod cover 14. Typically, a lot number 8 is inscribed by a laser adjacent to the wafer edge 4 in the silicon layer on the patterned side of the wafer 1 where electronic devices are built. Facility personnel can thus visually read the lot number 8 through the transparent cover top 22 of the pod cover 14 and thus, monitor or track the course of the SMIF pod 10 through the facility and make any necessary adjustments in transport of the SMIF pod 10. Alternatively, the lot number 8 may be provided on the wafer cassette 24 or on the inside surface of one of the cover sides 16 or on any other suitable element inside the SMIF pod 10.

Because the

lot number

8 inscribed on the wafer 1 or provided elsewhere inside the SMIF pod 10 is typically small, however, it is often difficult for facility personnel to accurately visually read and identify the lot number 8 through the pod cover 14 without first removing the SMIF pod 10 from a transporting vehicle or stocker. In some cases, a magnifying glass (not illustrated) may be held adjacent to the pod cover 14 after removal of the SMIF pod 10 from the transport vehicle or stocker to render the lot number 8 easier to read. This procedure is time-consuming and interrupts orderly and timely transport of the wafers 1 throughout the facility.

Accordingly, a device is needed for facilitating quicker and more accurate visual determination of the lot number on a semiconductor wafer or elsewhere in a wafer container.

SUMMARY OF THE INVENTION

An object of the present invention is to provide a device for the accurate identification of items in a container.

Another object of the present invention is to provide a device and method for the timely and accurate identification of an identification number inside a container for an item or items in the container.

Another object of the present invention is to provide a device for the accurate identification of semiconductor wafers in a wafer pod or container.

Still another object of the present invention is to provide a mechanism for the accurate identification of semiconductor wafers in a standard mechanical interface (SMIF) pod without the need for interrupting orderly and timely transport of the SMIF pod from one location to another in a semiconductor fabrication facility.

Yet another object of the present invention is to provide a mechanism which contributes to orderly and accurate transport of semiconductor wafers in a semiconductor fabrication facility.

Still another object of the present invention is to provide a mechanism for quick and accurate identification of semiconductor wafers in a wafer container or pod without first requiring removal of the wafer container or pod from a transport vehicle or stocker in a semiconductor fabrication facility.

A still further object of the present invention is to provide a mechanism which facilitates quick and accurate identification of the lot number of semiconductor wafers in a wafer pod or container.

Yet another object of the present invention is to provide a method of facilitating quick and accurate identification of semiconductor wafers by lot number or other category as the wafers travel from one processing tool or station to another or as the wafers are stored in a stocker in a semiconductor fabrication facility.

In accordance with these and other objects and advantages, the present invention comprises a wafer pod or container fitted with at least one magnifying lens for magnifying the image of a lot number or other identifying indicia typically inscribed on a wafer inside the pod or container. The magnifying lens enables quick and accurate visual identification of the wafers by lot number or other identifying indicia as the wafers are transported in a semiconductor wafer fabrication facility.

The lot number or other wafer-identifying indicia may be inscribed on a wafer or wafers inside the container or pod or provided on a wafer cassette or other element inside the wafer container or pod. Accordingly, the magnifying lens or lenses may be provided in the top or one or more sides, or both, of the wafer container or pod to facilitate magnification of the identifying indicia inside the container or pod and accurate and timely tracking and/or correction in the course of travel or storage of the wafers throughout the semiconductor production process, as necessary. The magnifying lens or lenses may have any desired magnification power, typically but not necessarily in the range of from about 2× to about 50× magnification power.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will now be described, by way of example, with reference to the accompanying drawings, in which: [0023]
FIG. 1 is an exploded, perspective view of a typical conventional SMIF pod, used in conjunction with a port assembly of a standard mechanical interface on a wafer processing tool or station; [0024]
FIG. 2 is a top view of the wafer cassette container or pod illustrated in FIG. 1, with a wafer substrate contained inside the container or pod and a lot number inscribed on the wafer visible through the transparent pod cover thereof; [0025]
FIG. 3 is a perspective view of an illustrative embodiment of a wafer container or pod of the present invention; [0026]
FIG. 4 is a cross-sectional view, taken along section line [0027] 4-4 in FIG. 3; and
FIG. 5 is a top view of the wafer container or pod of the present invention, in typical application of the invention. [0028]

DESCRIPTION OF THE PREFERRED EMBODIMENTS

When used herein, the term cover shall be understood to mean any object capable of partially or completely enclosing one or more articles. When used herein, the term identifying indicia shall be understood to mean any marking, writing or inscription consisting of numbers, letters or both, provided on a surface to identify an article or articles. When used herein, the term magnifying lens shall be understood to mean any plastic or glass lens capable of magnifying an image of an object. [0029]
The present invention has particularly beneficial utility in the quick, accurate and convenient identification of semiconductor wafers inside a wafer container or pod used to transport or store the wafers in a semiconductor production facility. However, the invention is not so limited in application, and while references may be made to such wafer container or pods, the invention may be applicable to the quick and accurate identification of items in a closed container in a variety of industrial and product applications. [0030]
In an illustrative embodiment, the present invention is directed to a wafer pod or container having at least one magnifying lens provided in the top or side thereof, or both, for magnifying the image of a lot number or other identifying indicia either inscribed on a wafer inside the pod or container or provided on a wafer cassette or other element in the container. The magnifying lens or lenses enable facility personnel to quickly and accurately identify the wafers by lot number or other identifying indicia inside the pod or container as the wafers are transported or stored in a semiconductor wafer fabrication facility. [0031]
Referring to FIGS. [0032] 3-5, an illustrative embodiment of the wafer container of the present invention is generally indicated by reference numeral 35 and may be a SMIF pod or any other type of wafer transport or storage container known by those skilled in the art. The wafer container 35 typically includes a pod cover 37 having multiple cover sides 40 and a cover top 39. The pod cover 37 may be constructed of clear polycarbonate, Lexan or any other clear or transparent material. Alternatively, the pod cover 37 may be constructed of an opaque or colored plastic or other material. A cover base 47 may be provided at the bottom end of the pod cover 37 for removably receiving a pod door 38. A latch mechanism (not illustrated), which may be conventional, is used to removably latch the pod door 38 on the cover base 47 and seal a wafer cassette 43 (FIG. 5) holding multiple semiconductor wafers 45 inside the pod cover 37.
A magnifying [0033] lens 41, which may be oval, as illustrated, or any other suitable shape, is typically seated in a lens opening 42 which extends through the cover top 39, as illustrated in FIG. 4. It is understood that various other configurations may be used to seat or attach each magnifying lens 41 to the pod cover 37. The magnifying lens 41 may be formed of Lexan or any other transparent magnifying glass or plastic. A magnifying lens 41 is typically located adjacent to one or more cover edges 44 where the cover top 39 meets the respective cover sides 40 of the pod cover 37. In the embodiment illustrated in FIG. 3, a pair of magnifying lenses 41 is provided in the cover top 39, adjacent to opposite cover edges 44. However, it is understood that either one magnifying lens 41 or multiple magnifying lenses 41 may be provided in the cover top 39 at any location or locations therein to facilitate visual image magnification and identification of identifying indicia 49 inside the wafer container 35, as illustrated in FIG. 5 and hereinafter further described. A magnifying lens or lenses 41 may alternatively or additionally be provided in one or more of the cover sides 40, as illustrated in phantom in FIG. 3. The magnifying lens or lenses 41 may be provided anywhere on the pod cover 37 in sufficient viewing proximity to identifying indicia 49 for the wafers 45 inside the wafer container 35. Each of the magnifying lenses 41 may have any desired magnification power or strength, but the magnification power of the magnifying lenses 41 is typically in the range of from about 2× to about 50×.
Application of the [0034] wafer container 35 of the present invention is as follows. Identifying indicia 49, typically including a lot identification number, is inscribed by a laser (not illustrated) adjacent to the wafer edge 46 of each of the multiple semiconductor wafers 45 in a common lot at the beginning of the semiconductor production process. Multiple wafers 45 in the same lot are loaded onto a wafer cassette 43, which is supported on the pod door 38 of the wafer container 35. The pod door 38 is then removably attached to the cover base 47 preparatory to transporting the wafers 45 in the wafer container 35 throughout the semiconductor fabrication facility. Instead of being inscribed or otherwise imprinted upon the wafers 45, the identifying indicia 49 may be provided on the wafer cassette 43, on the inside surface of one of the cover sides 40, or on any other suitable supporting element inside the wafer container 35. In the case of the wafer container 35 illustrated in the drawings, the identifying indicia 49 inscribed on the top wafer 45 on the wafer cassette 43 is positioned beneath one of the magnifying lenses 41 provided in the cover top 39 upon placement of the wafer cassette 43 and wafers 45 in the wafer container 35. Accordingly, the image of the identifying indicia 49 is magnified and rendered easily visible through the magnifying lens 49 in such a manner that the identifying indicia 49 can be readily, accurately and conveniently identified by facility personnel tracking the lot of wafers 45 throughout the facility. This identification procedure can be performed without first requiring the removal of the wafer container 35 from the transport vehicle or stocker (not illustrated) and then replacement of the wafer container 35 back on the transport vehicle or stocker after identification, which would significantly reducing lag time in the transport of the wafer container 35 and wafers 45 throughout the facility.
While the preferred embodiments of the invention have been described above, it will be recognized and understood that various modifications can be made in the invention and the appended claims are intended to cover all such modifications which may fall within the spirit and scope of the invention. [0035]

Claims

What is claimed is:

1. A container for containing an article and identifying indicia for the article, said container comprising:

a cover for containing the article; and

at least one magnifying lens provided in said cover for viewing the indicating indicia from outside said cover.

2. The container of claim 1 wherein said at least one magnifying lens comprises a plurality of magnifying lenses.

3. The container of claim 1 wherein said cover comprises a plurality of cover sides and a cover top provided on said plurality of cover sides and said at least one magnifying lens is provided in said cover top.

4. The container of claim 3 wherein said at least one magnifying lens comprises a plurality of magnifying lenses.

5. The container of claim 1 wherein said container comprises a SMIF pod and further comprising a pod door for removably engaging and closing said cover.

6. The container of claim 5 wherein said at least one magnifying lens comprises a plurality of magnifying lenses.

7. The container of claim 5 wherein said cover comprises a plurality of cover sides and a cover top provided on said plurality of cover sides and said at least one magnifying lens is provided in said cover top.

8. The container of claim 7 wherein said at least one magnifying lens comprises a plurality of magnifying lenses.

9. A container for containing an article and identifying indicia for the article, said container comprising:

a cover for containing the article;

a cover base provided on said cover;

a cover door for removably engaging said cover base; and

10. The container of claim 9 wherein said at least one magnifying lens comprises a plurality of magnifying lenses.

11. The container of claim 9 wherein said cover comprises a plurality of cover sides and a cover top provided on said plurality of cover sides and said at least one magnifying lens is provided in said cover top.

12. The container of claim 9 wherein said at least one magnifying lens has a power of from about 2× to about 50×.

13. A method of enhancing speed and accuracy of identifying semiconductor wafers located inside a container from outside the container, said method comprising the steps of:

providing identifying indicia for said semiconductor wafers inside said container;

providing at least one magnifying lens on said container; and

magnifying said identifying indicia by visually observing said identifying indicia through said at least one magnifying lens.

14. The method of claim 13 wherein said providing identifying indicia for said semiconductor wafers inside said container comprises the step of providing said identifying indicia on at least one of said semiconductor wafers.

15. The method of claim 13 wherein said container comprises a cover having a plurality of cover sides and a cover top provided on said plurality of cover sides and wherein said providing at least one magnifying lens on said container comprises the step of providing at least one magnifying lens on said cover top.

16. The method of claim 15 wherein said providing identifying indicia for said semiconductor wafers inside said container comprises the step of providing said identifying indicia on at least one of said semiconductor wafers.

17. The method of claim 15 wherein said providing at least one magnifying lens on said container comprises the step of providing at least one magnifying lens on at least one of said plurality of cover sides, respectively.

18. The method of claim 13 further comprising the steps of providing a wafer cassette in said container and providing said semiconductor wafers on said wafer cassette, and wherein said providing identifying indicia for said semiconductor wafers inside said container comprises the step of providing said identifying indicia on said wafer cassette.

19. The method of claim 18 wherein said container comprises a cover having a plurality of cover sides and a cover top provided on said plurality of cover sides and wherein said providing at least one magnifying lens on said container comprises the step of providing at least one magnifying lens on said cover top.

20. The method of claim 19 wherein said providing at least one magnifying lens on said container further comprises the step of providing at least one magnifying lens on at least one of said plurality of cover sides, respectively.