Data processing: generic control systems or specific application – Specific application – apparatus or process – Product assembly or manufacturing
Reexamination Certificate
1999-08-31
2001-10-23
Grant, William (Department: 2121)
Data processing: generic control systems or specific application
Specific application, apparatus or process
Product assembly or manufacturing
C414S937000, C414S940000, C700S112000, C700S099000
Reexamination Certificate
active
06308107
ABSTRACT:
FIELD OF THE INVENTION
The present invention generally relates to automated material handling systems and, more particularly, to a system and a method for reducing transportation time delays via a real time decision making system as part of an automated material handling systems.
BACKGROUND OF THE INVENTION
Automated material handling systems are used in a variety of industries to move various materials from one location to another location. Semiconductor fabrication facilities, in particular, commonly utilize automated material handling systems for fabricating integrated circuits on semiconductor wafers.
A conventional semiconductor fabrication plant typically includes multiple fabrication areas or bays interconnected by a path, such as a conveyor belt. Each bay generally includes the requisite fabrication tools (interconnected by a subpath) to process semiconductor wafers for a particular purpose, such as photolithography, chemical-mechanical polishing, or chemical vapor deposition, for example. Material stockers or stocking tools generally lie about the plant and store semiconductor wafers waiting to be processed. The wafers are usually stored in cassettes each of which typically hold up to 25 wafers. A lot is a logical grouping of wafers in a cassette. The lot can migrate from cassette to cassette as it progresses through the chain of production processes Each material stocker typically services two or more bays and can hold hundreds of cassettes.
Once a lot has been retrieved, and the equipment has been set up, the operation on the wafers by a particular piece of equipment, or “tool,” can begin. At this point, the lot is moved-in to the operation. This state is indicated to the host application by the operator for the lot. The lot remains in this state until the operation is completed. Once the operation is completed, the operator must perform tests and verifications on the wafers. When all tests and verifications have been performed, the host computer application program must be notified. Wafers may have moved from one cassette to another as a result of the operation. The host application has to be notified of this. The operator then places the cassette of “moved-out” wafers in the material stocker, to await orders as to the location of the next piece of equipment that will perform operations on the wafers.
Some present material handling systems exhibit excess movement of materials through the system that negatively impacts manufacturing throughput. In an example system, there are multiple locations that are available for a particular manufacturing process step. However, the system only provides mappings for one location per manufacturing process step. Therefore, the system does not know that there are alternate locations available for performing the processing step. When the AMHS dispatches material to a particular location, and the stocker associated with that location is unavailable, the material is redirected to an adjacent stocker or temporary storage. If other locations are available to perform the processing step, a move request is required to transfer the material from a stocker, such as the adjacent stocker, to the desired location. The AMHS then moves the material to the stocker at the specified location, and the material is then removed and processed.
The semiconductor fabrication plant, including the bays, material stockers and the interconnecting path, typically operates under control of a distributed computer system running a factory management program, such as WorkStream Open sold by Consilium, Inc. In this environment, the automated material handling system (AMHS) may conceptually include the cassettes, the transportation system (e.g., paths) and control system (e.g., the distributed computer system). You may also have an empty carriers management system as well as a separate test wafer management system that form part of the AMHS. Currently these are handled as subsystems and must be manually coordinated by the operators on the line, which has led to delays in the system in processing the wafers. It would be desirable, therefore, to reduce processing delays and increase throughput efficiency by pre-positioning material at the different stocker locations through the use of current automated material handling systems.
SUMMARY OF THE INVENTIONS
Semiconductor fabrication facilities have material handling systems that manage production and test wafers as well as empty carriers separately throughout the system. Currently these are handled as subsystems and must be manually coordinated by the operators on the line, which has led to delays in the system in processing the wafers. It would be desirable to have an automated and integrated system to reduce delays due to products not being pre-positioned at a particular process location just before the prior lot is finished. It would be also desirable to have advanced notice of a downstream change in the system due to a malfunction or upstream command that will have a lot idling at a stocker location when it could have been re-routed where there is available capacity.
An example embodiment of the present invention is directed to a method for pre-positioning routed objects in a computer controlled manufacturing arrangement having alternate locations for predetermined ones of a plurality of manufacturing process steps and predetermined types of objects to be routed into alternate locations. The method includes establishing a distribution of events indicative of the alternate locations at which the object is processed for a manufacturing process step with respect to the objects to be routed and documenting the distribution of events in a database with respect to the type of objects to be routed and the alternate locations in terms of routing times, therein establishing a historical routing time for the type of object to be routed. In addition, there is established the actual mix of objects to be routed to the alternate locations and their historical routing time and an actual routing time for the type of routed objects are compared. Further, one of a plurality of substates is selected that include: pre-position routed objects when historical and actual times are substantially the same, hold routed object when the times are different and re-route object when time comparison is not available. Finally, one of a plurality of alternate locations is selected to which to route the object for the next manufacturing process step as a result of a one of the substates selected.
Another example embodiment of the present invention is directed to an apparatus for routing objects in a computer controlled manufacturing arrangement having alternate locations for predetermined ones of a plurality of manufacturing process steps and predetermined types of objects to be routed into alternate locations. The apparatus includes a mechanism for establishing a distribution of events indicative of the alternate locations at which object is processed for a manufacturing process step with respect to the objects to be routed and a mechanism for documenting the distribution of events in a database with respect to the type of objects to be routed and the alternate locations in terms of routing times, therein establishing a historical routing time for the type of object to be routed. The apparatus further includes a mechanism for establishing the actual mix of objects to be routed to the alternate locations and a mechanism for comparing historical routing time with actual routing time for a type of routed object. A mechanism is included that selects one of a plurality of substates that include: pre-position routed object when historical and actual times are substantially the same, hold routed object when the times are different and re-route object when comparison is not available and another mechanism is included that selects one of a plurality of alternate locations to which to route the object for the next manufacturing process step as a result of a one of the substates selected.
In accordance with another embodiment of the present invention there i
Conboy Michael R.
Coss Elfido
Ryan Patrick J.
Advanced Micro Devices , Inc.
Grant William
Hartman Jr. Ronald D
LandOfFree
Realtime decision making system for reduction of time delays... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Realtime decision making system for reduction of time delays..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Realtime decision making system for reduction of time delays... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2575977