GB2458746A

GB2458746A - Tracking apparatus

Info

Publication number: GB2458746A
Application number: GB0901700A
Authority: GB
Inventors: Gareth Rees; Owen Pullin; Jamie Roberts
Original assignee: Individual
Current assignee: Individual
Priority date: 2008-02-02
Filing date: 2009-02-02
Publication date: 2009-10-07
Also published as: GB0801961D0; WO2009095683A1; GB0901700D0; GB0815412D0

Abstract

A system for tracking the WIP storage location of each of a plurality of articles 11 between successive steps of a plurality of process operations there is provided a tracking system 10 and a storage tray 12 wherein a central processing unit comprises a data store 20, a plurality of individually identified storage sites 12, a plurality of first communication links each for two-way communication between the central processing unit and a storage site, a user interface associated with the central processing unit to display storage location information, and each storage tray comprising a detector 15 to receive information related to the identity of an article temporarily stored at that storage site and transmit said information and identity of that storage site to the central processing unit 34. The first communication links may be POE connections, and the storage tray may comprise a visual display 21 of information related to the identity of the article temporarily stored at that tray and a visual indicator 24 which is actuable to indicate that an article is due to be removed.

Description

TRACKING APPARATUS

This invention relates to tracking apparatus and to a tracking system which utilises said tracking apparatus for the purpose of tracking the location of articles and in particular, though not exclusively, for tracking the storage location of articles of type which require to be stored temporarily between successive manufacturing processes. The invention provides also a method of tracking the storage location of each of a plurality of articles and storage means for the temporary storage of tracked articles.

The need efficiently and reliably to track the storage location of artictes arises particularly in factories where semi-conductors are manufactured.

In the manufacture of semi-conductors silicone wafers need to be subjected to a considerable number of process operations over an extended period of time.

Thus a wafer typically may need to be subjected to at least thirty different process operations over a period of up to twenty weeks. For a significant part of that period the wafers need to be stored temporarily, awaiting the time that they are to be subject to the next stage of the manufacturing process -for example for availability of equipment for performing that next due process operation.

In contrast to many multi-stage manufacturing processes employed in other industries, the high degree of cleanliness required for the manufacture of semiconductors dictates that they cannot be stored in open conditions within the factory. Instead groups, known as "lots", typically comprising twenty five silicone wafers, are held in a cassette which in turn is stored in an air-tight manner in a sealed pod. The cassette is removed from the pod, in a manner that inhibits contamination, when silicone wafers are to be subject to one of the process operations, and then similarly returned to that pod for temporary storage until the next process operation is to be undertaken.

To assist in ensuring that the wafers in each pod are subjected to the correct sequence of process operations, and for quality control and product recall purposes, each pod, or cassette within a pod, carries a tag which has a unique "lot" identification number for the wafers contained in the pod. Each wafer held in the cassette has that lot identification number marked on it together with the individual number of the wafer within that cassette.

The identification number carried by the pod or cassette is logged by the manufacturers production equipment each time that the pod presents the cassette of wafers for a process operation. Accordingly the manufacturers "manufacturing execution system" (MES) can be employed to establish the location of each pod for which wafers are being subjected to a process operation. However, particularly because a semiconductor manufacturing facility typically will contain between 3,000 and 10,000 pods, much time often is wasted in physically locating pods which have been stored temporarily in readiness for the next process operation. Because of the different time intervals between different stages of manufacture it is not convenient simply to store the pods sequentially, for example on a moving conveyor as commonly employed in many other manufacturing facilities.

Various proposals have been advanced in an attempt to facilitate ease of location of temporarily stored pods but up to the time of making of the subject invention no efficient or reliable solution has been advanced.

The present invention seeks to provide an improved apparatus, system and method for the storage and tracking of the location of articles which require to be stored temporarily between successive manufacturing processes, and in particular which is suitable for use in a semiconductor manufacturing facility.

According to one aspect of the present invention a tracking system for tracking the storage location of each of a plurality of articles between successive steps of a plurality of process operations comprises:-a central processing unit comprising a data store; a plurality of individually identified storage sites; a plurality of first communication links each for communication between the central processing unit and a respective one of the storage sites; at least one user interface associated with said central processing unit and operable to receive an article storage location enquiry and to display storage location information, and each said storage site comprising detector means to receive information related to the identity of an article stored at that storage site and to transmit said information and the identity of that storage site to the central processing unit.

The present invention is of particular benefit as an intelligent work-in-progress (WIP) tracking system in a semiconductor manufacturing facility and in which each article typically is an enclosure which houses in a cassette a plurality of individual semiconductor wafers which are subjected to a sequence of different process operations. Thus in the case of the typical procedure for manufacture of semiconductors it is the contents of the article, i.e. the wafers within an enclosure such as a pod, which are subjected to process operations but more generally the present invention may be applied also to articles which are themselves subject to process operations.

It is known that for use in identification during successive manufacturing stages in the production of semiconductor wafers each pod or cassette will carry a unique lot identification for a group of wafers and typically that may be presented in the form of a bar code, a liquid crystal display (LCD) tag or a radio frequency identification (RFID) tag.

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The work-in-progress tracking system of the present invention may comprise at each storage site a detector of a kind specifically adapted to receive identification information from a source in the particular form in which it is to be presented by the pods or cassettes with which the work-in-process system is to be used or some or all of the storage sites may be provided with multi-functional detector means thereby to be able to receive identification information presented by a pod or cassette in any one of two or more different forms. Thus a storage site may comprise a detector means which comprises one or more of a bar code reader, an infra red receiver for reading an LCD tag and an RFID reader for reading an RFID tag, thereby to establish the identification of an article received at the storage site.

The invention further envisages that each storage site comprises electronic processor means, such as an SBC (single board computer), which may be remotely programmed and configured to function with different types of detector means.

A storage site may be provided with a multi-functional detector means as described above or it may be provided with attachment means, such as one or more sockets, whereby different types of detector means may be secured relative to the storage site.

Each storage site may be provided with guide means, such as a recessed region, whereby an article such as a pod placed at that site for temporary storage is held in a position at which the detector means at that site is able effectively to read the identification information carried by that article.

A storage site may be in the form of a tray comprising an integral assembly of guide means and detector means and typically a plurality of trays may be secured to shelves or mounted on open racks.

In an alternative arrangement a support structure such as a storage shelf may comprise a plurality of detector means each secured to the support structure at spaced positions whereby an article for temporary storage may be aligned with the detector means at a vacant storage site. The support structure preferably also comprises a plurality of guide means each secured to the support structure and adapted to tend to align an article with a detector means when the article is placed on the support structure.

Preferably each of the first communication links if a two-way communication link operable both to transmit information to the central processing unit and to receive information from the central processing unit. Thus in addition to sending information from a storage site to the central processing unit, the communication link may serve also to send a signal to the storage site when an article is due to be removed from the storage site. That signal may be employed at the storage site to activate an indicator, e.g. to illuminate a lamp thereby to make readily apparent to an operator the particular location from which an article such as a pod is to be removed. Preferably a sensor means is provided to de-activate the indicator when the article has been removed, and more preferably to transmit a signal to the central processing unit to indicate that that storage site has become vacant. The sensor means may be operable also to sense arrival of an article at a storage site and transmit that information to the central processing unit.

To further assist in ensuring that a correct article is removed at a time when several articles are due to be removed from storage, for example for submitting of the articles or their contents to further process operations, the central processing unit may be adapted to restrict the number of indicators that can be activated at any one time. Thus, for example, it may be ensured that at any one moment in time only one indicator may be in operation, or if storage sites are positioned at two or more physically or visually separated zones of a manufacturing facility, only one indicator at each said zone is in operation at any one moment in time.

The present invention teaches that each or at least some of said first communication links are ethernet connections, but alternative one or more of the first communication links may be a wireless type of communication link.

Preferably each first communication link is a POE (power over ethernet) connection operable to allow two-way communication between the central processing unit and a storage site, e.g. each storage tray, and to provide power to the storage site.

Preferably the tracking system comprises a POE interface, e.g. a PC terminal, which allows only a user with administrator status to re-configure and or upgrade the software of processor means at a plurality of storage trays. More preferably the system allows a plurality of storage sites to be re-configured and or upgraded simultaneously. Thus, for example, if a number of trays fitted with RFID pills have those pills replaced by others having different characteristics, the trays fitted with the different REID pills may readily be simultaneously re-configured by a user having "administrator" status.

A particular function of the central processing unit is to act as a data source and for that purpose preferably it comprises a database store to store updated information regarding the identity of all articles stored at the storage sites from which the central processing unit receives information, and the location of the site at which each article is stored. The database may store a unique identification code for each storage site and information relating to the physical location of the site. That database is employed by the central processing unit in order to respond to a request for location information received from a user at one or more of the user interfaces, and to provide that user with the required storage site location information.

It is not essential that the central processing unit comprises a data store. In an alternative configuration it may be operable sequentially to interrogate information held at each storage site to locate a site at which a particular article is situated.

Additionally the central processing unit may be inter-linked with a manufacturer's control system, such as a manufacturing execution system (MES) and which typically holds information regarding which articles, e.g. pods, are the subject of a process operation at any one moment in time. That inter-linking will enable the storage location information held on the central processing unit of the tracking system to be inputted into the manufacturer's system. Thus the manufacturer's system is able to make available a more complete body of information regarding the instantaneous location of each of the articles within the manufacturing facility.

According to another aspect of the present invention there is provided storage means for the location of an article of a type which bears an identification tag and whereby said article may be stored between successive manufacturing operations, said storage means comprising guide means to assist in location of the article in a pre-determined position, or in a range of positions, relative to the storage means, and said storage means further comprising a detector means to read an identification tag carried by the article, said storage means comprising an output to a communication link for communicating to a remote processing unit the arrival of an article and the information read by the detector means and to communicate to the remote processing unit the removal of the article from the storage means, said storage means further comprising a visual display to display the identity tag information received by said detector means.

The storage means may comprise a sensor which may be independent of the detector means and operable to detect the arrival of an article at the storage means and removal of that article from the storage means.

Preferably the storage means additionally comprises an indicator, such as a lamp, which is activated when the storage means receives, via a communication link with an remote processing unit, a signal that the article at said storage means is due to be removed for a further processing operation.

Preferably the storage means additionally comprises a status indicator such as an LED or similar illumination means which, when illuminated, confirms that the storage means is in a fully operational, defect free condition.

The indicator for indicating that an article is due to be removed from the storage means may, for example, comprise a high intensity and/or flashing lamp, such as an LED light.

In addition to displaying identity information regarding an article stored at the storage means, said storage means may display information related to the identity of that storage means, and/or the position of that storage means amongst an array of other such storage means.

Typically the storage means may be in the form of a tray having a recess region shaped to accommodate an article, such as a pod containing a cassette of silicone wafers, and to locate that pod in a manner such that an identification tag carried by the pod is correctly positioned for reading by the detector means of the storage means.

The storage tray or like means may comprise addressing means which may be adjusted to provide the tray with a unique identity, and means may be provided for communicating that identity to a central data store and or for visually displaying that identity on the tray. An example of a suitable addressing means is a group of four 16-position rotary switches each adjustable such that in a collection of a considerable number of trays, for example up to 65,536 trays per operator terminal, each tray may be given a unique hexadecimal network address. Typically that address is one which corresponds with the physical location of the tray -e.g. rack unit A, shelf B and position C on that shelf.

The tray may comprise an integral RFID antenna or a socket for an external antenna.

According to a further of its aspects the present invention provides a method for tracking the location of work-in-progress articles, said method comprising use of a tracking system in accordance with the present invention and a plurality of storage means each of a kind in accordance with the present invention.

One embodiment of the present invention will now be described, by way of example only, with reference to the accompanying diagrammatic drawings in which:-Figure 1 illustrates part of a work-in-progress tracking system in accordance with the present invention; Figure 2 is a front perspective view of a storage tray in accordance with the present invention; Figure 3 is a rear perspective view of the storage tray of Figure 2; Figure 4 is a perspective view of a semiconductor pod for use with the tray of Figure 2, and Figure 5 shows schematically the communication links within the storage tray of Figure 2.

A work-in-progress tracking system 10 (see Figure 1) for use in a semiconductor manufacturing facility for tracking the temporary, random storage location of storage pods 11 comprises a plurality of storage trays 12, typically between 3,000 and 10,000 storage trays at each of which any one of the manufacturing pods may be stored, each storage tray being in two-way communication with a remote, central database store 20.

The storage trays are each secured to shelving units in the form of racks 13 (two part shown in Figure 1) positioned at various locations within the manufacturing facility.

Each tray 12, see Figures 2 and 3, comprises a plastics moulding shaped to define a recess 14 for location of the base 9 of a manufacturing pod (see Figure 4) which in turn contains a cassette containing a group of silicone wafers. Each pod is of a kind having a standardised mechanical interface (SMIF) system so that the wafers may be stored in the pod, in an environmentally sealed manner, until they need to be transferred, via an air lock system, to apparatus for performing a manufacturing operation.

An LCD reader 15 is positioned at the rear 16 of the front panel 17 of the tray so as to face the confronting pod region 18 at which the pod bears an LCD display of the lot identification number of the cassette contained within the pod. The tray incorporates a POE terminal 19 for communication of the lot identity information to the remote data store 20, for supply of power to the tray, and for enabling a processor 26', such as a single board type computer, contained within the tray (see Figure 5) to be remotely programmed and or re-configured. The front panel 17 of the tray, incorporates an LCD display 21 which displays the information read by said LCD reader 15.

The middle of the tray 14 incorporates an optical sensor 22 which senses arrival and removal of a pod and provides a signal for transmitting that information, via POE output 19, to the remote data store 20.

The front panel 17 additionally is provided with a power-on lamp 23 which, when illuminated, confirms that the tray is functionally connected to the tracking system. The front face also is provided with an alert indicator 24 in the form of a high intensity LED lamp which is operable to flash when a pod is due to be removed from that tray.

The rear boundary of the tray is provided, at a position not normally visible from the front of the tray, with four 16-position rotary switches 25 which can be set to assign to that tray a unique tray identification code corresponding to the identity of the rack, shelf and shelf position at which that tray is installed. Said switches communicate with the output 19 whereby that identification code may be transmitted to the remote data store.

The rear boundary of the tray also incorporates an auxiliary pcb program port 26, an external RFID antenna port 27, a pcb reset switch 28, a test port 29, a display contrast control 35, and a group 36 of output LED's responsive to status of network functions and pod-in-place status, The interconnection of the aforementioned components of the tray 12 is shown by broken lines on Figure 5.

Referring again to Figure 1, the output of each storage tray 12 communicates via a power over ethernet (POE) type connection 30 with a proprietary type POE switch 31 and in turn via an ethernet connection 32 and network switch 33 to the remote database store 20 of a central processing unit 34.

In a typical semiconductor factory there will be several physically separate sites at which storage racks are provided. In accordance with the present invention the trays at each site have a power over ethernet connection with one or more POE hubs 31, and an ethernet connection then communicates between the or each hub at each site and the central data store 20.

From the forgoing it will be apparent that the central database store 20 holds information concerning which storage trays 12 are occupied by a pod 11, the identity of that tray, i.e. the physical location of the tray on one of the racks, and the identification code of a pod or the pod contents, stored at that tray.

The information held by the central data store 20 is accessible from each of a plurality of remote computer terminals 40 -40n connected to the central processing unit 34. The central processing unit is operable to respond to requests from each terminal for the physical location of any one of the pods which may be stored in one of the trays 12. The central processing unit may then automatically, or subject to confirmation of the request from the user at the remote terminal, send a signal to the tray to activate the high intensity LED lamp 24. Subsequent removal of the pod from a tray is sensed by the optical sensor 22. In response to receipt of that removal information by the central processing unit, the central processing unit switches off power to the LED lamp and updates the display at the front of the tray to a blank screen until the next pod arrives and causes the display to display a new lot identification..

The information held in the data store 20 is also accessible by the manufacturer's MES 50 via link 51. Additionally information in the MES is also available at the aforementioned terminals 40 -40n via link 52.

Accordingly it will be understood that the aforedescribed storage tray and storage tracking system facilitate the speedy and reliable identification of the location of any temporarily stored pod and that by a substitution of the LED reader 15 for a barcode reader or RFID reader the tray and system may readily be employed in manufacturing facilities which employ pods of the type that carry a barcode, or for example, contain a wafer cassette to which an RFID tag is attached.

FABDE4

Claims

Claims 1. A tracking system 10 for tracking the storage location of each of a plurality of articles 11 between successive steps of a plurality of process operations comprises a central processing unit 34 comprising a data store 20; a plurality of individually identified storage sites 12; a plurality of first communication links 32 each for communication between the central processing unit 34 and a respective one of the storage sites 12; at least one user interface 40 associated with said central processing unit and operable to receive an article storage location enquiry and to display storage location information, and each said storage site 12 comprising detector means 15 to receive information related to the identity of an article 11 stored at that storage site and to transmit said information and the identity of that storage site to the central processing unit 34.
2. A tracking system according to claim I wherein each said first communication link 32 is a power over ethernet (POE) connection.
3. A tracking system according to claim I or claim 2 wherein each first communication link 32 is a two-way communication link operable both to transmit information to the central processing unit 34 and to receive information from the central processing unit.
4. A tracking system according to claim 3 wherein said communication link 32 is operable to send a signal to a storage site 12 when an article 11 is due to be removed from that storage site.
5. A tracking system according to claim 4 wherein said signal causes activation of an indicator light 24.
6. A tracking system according to claim 5 and comprising means 22 to de-activate said indicator light 24 when the storage site had become vacant. w
7. A tracking system according to any one of claims 4 to 6 wherein the central processing unit 34 is operable to restrict the number of indicators 24 that can be activated at any one time.
8. A tracking system according to any one of the preceding claims wherein the central processing unit 34 comprises a data base store 20 containing updated information regarding the identity of all articles 11 stored at the storage sites 12 from which the central processing unit receives information, and the location of the site at which each article is stored.
9. A tracking system according to claim 8 wherein the data base 20 is operable to respond to a request for location information and provide to the requester the required storage site location information.
10. A tracking system according to any one of the preceding claims wherein each storage site 12 comprises processor means 26', such as a single board computer, which is remotely programmable and or re-configurable.
11. A tracking system according to claim 10 wherein the central processing unit is operable simultaneously to re-program and or re-configure each of the processor means at said storage sites 12.
12. A tracking system according to any one of the preceding claims wherein each storage site comprises a detector means 15 which comprises one or more of a bar code reader, an infra-red receiver for reading an LCD tag and an RFID reader for reading an RFID tag. S..
13. A tracking system according to any one of the preceding claims wherein each storage site 12 comprises guide means for selective positioning of an article at said storage site. *5 *Sp *S S SS
14. A tracking system according to any one of the preceding claims wherein each storage site 12 comprises a tray 12 comprising an integral assembly of guide means and detector means 15.
15. A tracking system according to claim 14 wherein each tray 12 comprises a remotely programmable and or re-configurable processor means 26.
16. A tracking system according to claim 14 or claim 15 wherein each tray 12 is provided with an indicator light 24 which is arranged to illuminate when an article 11 is due to be removed from the tray.
17. A tracking system according to any one of claims I to 13 and comprising a support structure comprising a plurality of detector means each secured to the support structure at spaced positions whereby an article 11 for temporary storage may be aligned with the detector means 15 at a vacant storage site.
18. A tracking system according to claim 17 wherein said support structure comprises a plurality of guide means adapted to tend to align an article with a detector means when an article is placed on the support structure.
19. A tracking system according to claim I and substantially as hereinbefore described.
20. Storage means 12 for the location of an article 11 of a type which bears an identification tag and whereby said article may be stored between successive manufacturing operations, said storage means comprising guide means to assist in location of the article in a pre-determined position, or in a range of positions, relative to the storage means, and said storage means further comprising a detector means 15 to read an identification tag carried by the article, said storage means comprising an output 19 to a communication link for communicating to a remote processing unit 20 the arrival of an article and the information read by the detector means and to communicate to the remote processing unit the removal of the article from the storage means, said storage means further comprising a visual display 21 to display the identity tag information received by said detector means 15.
21. Storage means according to claim 20 wherein said detector means 15 is operable also to sense the arrival of an article at the storage means and the removal of an article from the storage means.
22. Storage means according to claim 20 and comprising a sensor means 22 separate from said detector means 15 and operable to detect the arrival of an article 11 at the storage means and removal of that article 11 from the storage means.
23. Storage means according to any one of claims 20 to 22 and comprising an indicator 24 remotely actuable to indicate that an article at said storage means is due to be removed for a further processing operation.
24. Storage means according to claim 23 wherein said indicator 24 comprises an LED light.
25. Storage means according to any one of claims 20 to 24 and comprising a status indicator 23 operable to confirm that the storage means is in a fully operational condition.
26. Storage means according to any one of claims 20 to 25 and comprising display means 21 operable to display information related to the identity of that storage means and/or the position of that storage means amongst an array of other such storage means.
27. Storage means according to any one of claims 20 to 26 and comprising a tray 12 having a recess region 14 shaped to accommodate and locate an article 11 in a manner in which a pre-determined part 9 of that article is correctly positioned relative to said detector means.
28. Storage means according to any one of claims 20 to 27 and comprising addressing means 25 adjustable to provide the storage means with a unique address identity.
29. Storage means according to claim 28 and comprising means whereby said unique address identity may be communicated to a data store external of the storage means.
30. Storage means according to claim 28 or claim 29 and comprising means for visually displaying said address identity.
31. Storage means according to claim 30 wherein said address identity is displayed by said visual display which displays identity tag information received by the detector means 15.
32. Storage means according to any one of claims 20 to 31 and comprising a processor means 26'.
33. Storage means according to claim 32 wherein said processor means is a remotely programmable and or re-configurable processor means 26'.
34. Storage means according to any one claims 20 to 33 and comprising a POE terminal for connecting the storage means 12 to said communication link.
35. Storage means according to claim 20 and substantially as hereinbefore described.
36. A method for tracking the location of work-in-process articles 11, said method comprising use of a tracking system 10 according to claim I and a plurality of storage means 12 each of a kind in accordance with claim 20.
37. A method according to claim 36 and substantially hereinbefore described.FABCL3