Subclass 7	Subclass 8	Subclass 9
Allocating resources or scheduling for an administrative function

Agent reactive scheduling in an automated manufacturing environment

6968248

Abstract

A method and apparatus for scheduling in an automated manufacturing environment, comprising are disclosed. The method includes detecting an occurrence of a predetermined event in a process flow; notifying a software scheduling agent of the occurrence; and reactively scheduling an action from the software scheduling agent responsive to the detection of the predetermined event. The apparatus is automated manufacturing environment including a process flow and a computing system. The computing system further includes a plurality of software scheduling agents residing thereon, the software scheduling agents being capable of reactively scheduling appointments for activities in the process flow responsive to a plurality of predetermined events.

Claims

1. A method for scheduling in an automated manufacturing environment, comprising:

automatically detecting an occurrence of a predetermined event in an integrated, automated process flow;

automatically notifying a software scheduling agent of the occurrence; and

reactively scheduling an action from the software scheduling agent responsive to the detection of the predetermined event.

2. The method of claim 1, wherein automatically detecting the occurrence of the predetermined event includes detecting an unplanned event or an unexpected event.

3. The method of claim 1, wherein automatically detecting the occurrence of the predetermined event includes detecting an occurrence of an appointment state change.

4. The method of claim 3, wherein automatically detecting the appointment state change includes detecting at least one of an appointment cancellation, an appointment expansion, an appointment shrinking, an appointment abort, an appointment changing status, an appointment shift, an appointment override, an transport time update, a load time update, an unload time update, a lot joining a batch, a lot leaving a batch, canceling a lot from a batch, and a commitment window update.

5. The method of claim 1, wherein automatically detecting the predetermined event includes detecting at least one of an appointment cancellation, an appointment expansion, an appointment shrinking, an appointment abort, an appointment becoming active, an appointment nearing completion, an appointment completing, an appointment shift, an appointment override, and a commitment window update, detection of a downtime occurrence; a machine becoming available; a PM/Qual being detected; a chamber going down; a chamber becoming available, a change in machine capabilities; a change in machine types; an addition of a process; an addition of a process operation; a lot arriving at a machine; a lot process changed, a lot placed on hold, a lot released from hold, a lot priority changed, a lot due date changed, a lot wafer count changed, a lot process operation changed, a lot departing a machine, an alarm firing for an appointment start time and an alarm firing for an appointment end time.

6. The method of claim 1, wherein automatically notifying the software scheduling agent of the occurrence includes:

sending an indication of the occurrence to a publisher;

publishing the occurrence from the publisher to a subscribing listener; and

calling the software scheduling agent from the subscribing listener.

7. The method of claim 1, wherein reactively scheduling the action includes at least one of aborting a scheduled appointment in progress; canceling a scheduled appointment duration of a scheduled appointment; shrinking the duration of a scheduled appointment; shifting a scheduled appointment; adding new processing capabilities; deleting old processing capabilities; setting an alarm; canceling an alarm; and changing the status of an appointment.

8. The method of claim 1, further comprising proactively scheduling an appointment with which the predetermined event is associated.

9. The method of claim 8, wherein proactively scheduling the appointment includes proactively scheduling the appointment from the software scheduling agent.

10. The method of claim 1, wherein detecting the occurrence of the predetermined event includes detecting an occurrence of a factory state change.

11. The method of claim 10, wherein automatically detecting the factory state change includes detecting at least one of detection of a downtime occurrence; a machine becoming available; a PM/Qual being detected; a chamber going down; a chamber becoming available, a change in machine capabilities; a change in machine types; an addition of a process; an addition of a process operation; a lot arriving at a machine; a lot process changed, a lot placed on hold, a lot released from hold, a lot priority changed, a lot due date changed, a lot wafer count changed, a lot process operation changed, and a lot departing a machine.

12. The method of claim 1, wherein detecting the occurrence of the predetermined event includes detecting an occurrence of an alarm event.

13. The method of claim 12, wherein automatically detecting the alarm event includes detecting at least one of an alarm firing for an appointment start time and an alarm firing for an appointment end time.

14. An automated manufacturing environment, comprising:

an integrated, automated process flow; and

a computing system, including a plurality of software scheduling agents residing thereon, the software scheduling agents being capable of reactively scheduling appointments for activities in the process flow responsive to an automatic detection and notification of a plurality of predetermined events.

15. The automated manufacturing environment of claim 14, further comprising a plurality of publishers and subscribers capable of detecting an occurrence of one of the predetermined events in the process flow and notifying one of the software scheduling agent of the occurrence.

16. The automated manufacturing environment of claim 15, wherein the automatic detection of the predetermined event includes detecting an unplanned event or an unexpected event.

17. The automated manufacturing environment of claim 15, wherein the automatic detection of the predetermined event includes detecting an occurrence of an appointment state change.

18. The automated manufacturing environment of claim 15, wherein the automatic notification of the software scheduling agent of the occurrence includes:

sending an indication of the occurrence to a publisher;

publishing the occurrence from the publisher to a subscribing listener; and

calling the software scheduling agent from the subscribing listener.

19. The automated manufacturing environment of claim 15, wherein reactively scheduling the action includes at least one of aborting a scheduled appointment in progress; canceling a scheduled appointment before it begins; scheduling a new appointment; starting a scheduled appointment; expanding the duration of a scheduled appointment; shrinking the duration of a scheduled appointment; shifting a scheduled appointment; adding new processing capabilities; deleting old processing capabilities; setting an alarm; canceling an alarm; and changing the status of an appointment.

20. The automated manufacturing environment of claim 15, further comprising proactively scheduling an appointment with which the predetermined event is associated.

21. The automated manufacturing environment of claim 15, wherein the automatic detection of the predetermined event includes detecting an occurrence of a factory state change.

22. The automated manufacturing environment of claim 15, wherein the automatic detection of the predetermined event includes detecting an alarm event.

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention pertains to automated manufacturing environments, and, more particularly, to scheduling in an automated manufacturing environment.

2. Description of the Related Art

Growing technological requirements and the worldwide acceptance of sophisticated electronic devices have created an unprecedented demand for large-scale, complex, integrated circuits. Competition in the semiconductor industry requires that products be designed, manufactured, and marketed in the most efficient manner possible. This requires improvements in fabrication technology to keep pace with the rapid improvements in the electronics industry. Meeting these demands spawns many technological advances in materials and processing equipment and significantly increases the number of integrated circuit designs. These improvements also require effective utilization of computing resources and other highly sophisticated equipment to aid, not only design and fabrication, but also the scheduling, control, and automation of the manufacturing process.

Turning first to fabrication, integrated circuits, or microchips, are manufactured from modern semiconductor devices containing numerous structures or features, typically the size of a few micrometers. The fabrication process generally involves processing a number of wafers through a series of fabrication tools. Layers of materials are added to, removed from, and/or treated on a semiconducting substrate during fabrication to create the integrated circuits. The fabrication essentially comprises the following four basic operations:

layering, or adding thin layers of various materials to a wafer from which a semiconductor is produced;
patterning, or removing selected portions of added layers;
doping, or placing specific amounts of dopants in selected portions of the wafer through openings in the added layers; and
heat treating, or heating and cooling the materials to produce desired effects in the processed wafer.

Although there are only four basic operations, they can be combined in hundreds of different ways, depending upon the particular fabrication process. See, e.g., Peter Van Zant, Microchip Fabrication A Practical Guide to Semiconductor Processing (3d Ed. 1997 McGraw-Hill Companies, Inc.) (ISBN 0-07-067250-4). Each fabrication tool performs one or more of four basic operations. The four basic operations are performed in accordance with an overall process to finally produce the finished semiconductor devices.

Controlling a semiconductor factory fabricating such integrated circuits, however, is a challenging task. A semiconductor factory ("fab") is a complex environment where numerous parts, typically 40,000 wafers or more, and numerous part types, typically 100 part types or more, are simultaneously being manufactured. As each wafer moves through the semiconductor factory (or, "fab"), it may undergo more than 300 processing steps, many of which use the same machines. A large factory may contain approximately 500 computer-controlled machines to perform this wafer processing. Routing, scheduling, and tracking material through the fab is a difficult and complicated task, even with the assistance of a computerized factory control system.

Efficient management of a facility for manufacturing products such as semiconductor chips requires monitoring various aspects of the manufacturing process. For example, it is typically desirable to track the amount of raw materials on hand, the status of work-in-process and the status and availability of machines and tools at every step in the process. One of the most important decisions is selecting which lot should run on each machine at any given time. Additionally, most machines used in the manufacturing process require scheduling of routine preventative maintenance ("PM") and equipment qualification ("Qual") procedures, as well as other diagnostic and reconditioning procedures that must be performed on a regular basis. These procedures should be performed such that they do not impede the manufacturing process itself.

One approach to this issue implements an automated "Manufacturing Execution System" ("MES"). An automated MES enables a user to view and manipulate, to a limited extent, the status of machines and tools, or "entities," in a manufacturing environment. In addition, an MES permits dispatching and tracking of lots or work-in-process through the manufacturing process to enable resources to be managed in the most efficient manner. Specifically, in response to MES prompts, a user inputs requested information regarding work-in-process and entity status. For example, when a user performs a PM on a particular entity, the operator logs the performance of the PM (an "event") into an MES screen to update the information stored in the MES database with respect to the status of that entity. Alternatively, if an entity is to be put down for repair or maintenance, the operator will log this information into the MES database, which then prevents use of the entity until it is subsequently logged back up.

Although MES systems are sufficient for tracking lots and machines, such systems suffer several deficiencies, the most obvious of which are their passive nature, lack of advance scheduling and inability to support highly automated factory operations. Current MES systems largely depend on manufacturing personnel for monitoring factory state and initiating activities at the correct time. For example, a lot does not begin processing until a wafer fab technician ("WFT") issues the appropriate MES command. And, prior to processing, a WFT must issue an MES command to retrieve the lot from the automated material handling system ("AMHS") with sufficient advance planning that the lot is available at the machine when the machine becomes available. If the WFT does not retrieve the lot soon enough, or neglects to initiate processing at the earliest available time, the machine becomes idle and production is adversely impacted.

These types of deficiencies in the typical automated MES emphasize the importance of the WFT in the efficient operation of the manufacturing process. WFTs perform many vital functions. For instance, WFTs initiate dispatching, transport, and processing as their attention and time permits. They make scheduling decisions such as whether to run an incomplete batch, as opposed to waiting for additional approaching lots, or performing PM or qualification procedures instead of processing lots. WFTs perform non-value added MES transactions and utilize conventional factory control systems that are passive. In this context, the term "passive" means activities in the control system must be initiated by the WFT, as opposed to being self-starting or self-initiating.

However, the presence of WFTs also inevitably introduces some inefficiencies. There typically is a large difference between the performance of the best WFT and the performance of the worst WFT. A WFT typically simultaneously monitors the processing of multiple tools and lots, making it difficult to focus on an individual lot or tool. Furthermore, the size and complexity of the modern fabrication process flows makes it exceedingly difficult for a WFT to foresee and prevent downstream bottlenecks or shortages arising from upstream activities. Shift changes, rest breaks, and days off for the WFT also create inefficiencies or machine idle time that adversely impact the manufacturing process flow. Just as the importance of the WFT is magnified by the deficiencies of the automated MES, so are the inefficiencies of the WFT magnified by his importance.

Thus, factory control systems utilized in today's wafer tabs are passive and do not enable a high degree of automation. These systems are very dependent on WFTs and other factory staff to monitor the state of the factory, to continuously react to change, to make rapid logistical decisions, and to initiate and coordinate factory control activity in a timely manner. These WFTs are agents, providing the active element that is lacking in factory control systems. As a result, factory effectiveness in the highly competitive semiconductor industry is quite dependent on the availability, productivity, skill level, and consistency of these human agents. WFTs must monitor and operate a number of tools located in various bays in a fab. They are forced to multiplex across tools, bays, material handling systems and a variety of factory control systems. As a fab's production ramps and more complex processes are introduced, it becomes more difficult to meet the increased complexity and volume without increasing staff or system capabilities. WFTs visibility of upstream and downstream operations, tool state, work-in-process and resource availability is limited.

However, key logistical decisions are frequently based on this limited and dated information, which is only partially provided by factory control systems. WFTs spend a significant amount of time interacting with systems, monitoring factory events and state changes, and performing other non-value added functions, such as MES logging. Shift changes disrupt the operation of the fab as the technicians are temporarily unable to provide required monitoring and coordination. Despite the best efforts of the technicians, utilization of tools suffer, adversely impacting other key factory metrics including cycle time, inventory levels, factory output and mix. With the need for intrabay material handling to transport 12-inch wafers in new 300 mm wafer fabs, significant additional complexity is introduced. Conventional factory control systems are not capable of providing this level of detailed scheduling and execution control.

The present invention is directed to resolving, or at least reducing, one or all of the problems mentioned above.

SUMMARY OF THE INVENTION

The invention, in its various aspects and embodiments, is a method and apparatus for scheduling in an automated manufacturing environment. In one embodiment, a method comprises detecting an occurrence of a predetermined event in a process flow; notifying a software scheduling agent of the occurrence; and reactively scheduling an action from the software scheduling agent responsive to the detection of the predetermined event. Alternative embodiments include a computing system programmed to perform this method and a computer-readable program storage medium encoded with instructions to implement this method. In still another embodiment, the invention includes automated manufacturing environment, comprising a process flow and a computing system. The computing system further includes a plurality of software scheduling agents residing thereon, the software scheduling agents being capable of reactively scheduling appointments for activities in the process flow responsive to a plurality of predetermined events.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention may be understood by reference to the following description taken in conjunction with the accompanying drawings, in which like reference numerals identify like elements, and in which:

FIG. 1 conceptually depicts a portion of one particular embodiment of a process flow constructed and operated in accordance with the present invention;

FIG. 2 conceptually depicts, in a partial block diagram, selected portions of the hardware and software architectures, respectively, of the computing devices in FIG. 1;

FIG. 3 conceptually depicts one particular implementation of the apparatus of FIG. 1, i.e., in a portion of a process flow from a semiconductor fabrication facility, and the manner in which it schedules appointments for the consumption of resources;

FIG. 4 conceptually depicts a calendar of booked appointments;

FIG. 5 conceptually illustrates three related calendars of booked appointments;

FIG. 6A and FIG. 6B conceptually illustrates the changing of booked appointments to take advantage of early start times; and

FIG. 7A and FIG. 7B conceptually illustrate two circumstances in which booked appointments are changed to accommodate unexpectedly long durations for preceding booked appointments.

While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof have been shown by way of example in the drawings and are herein described in detail. It should be understood, however, that the description herein of specific embodiments is not intended to limit the invention to the particular forms disclosed, but on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention as defined by the appended claims.

DETAILED DESCRIPTION OF THE INVENTION

Illustrative embodiments of the invention are described below. In the interest of clarity, not all features of an actual implementation are described in this specification. It will of course be appreciated that in the development of any such actual embodiment, numerous implementation-specific decisions must be made to achieve the developers' specific goals, such as compliance with system-related and business-related constraints, which will vary from one implementation to another. Moreover, it will be appreciated that such a development effort, even if complex and time-consuming, would be a routine undertaking for those of ordinary skill in the art having the benefit of this disclosure.

FIG. 1 conceptually illustrates a portion of one particular embodiment of a process flow 100 constructed and operated in accordance with the present invention. The process flow 100 fabricates semiconductor devices. However, the invention may be applied to other types of manufacturing processes. Thus, in the process flow 100 discussed above, the lots 130 of wafers 135 may be more generically referred to as "work pieces." The process tools 115 and any process operations performed thereon need not necessarily be related to the manufacture of semiconductor devices in all embodiments. However, for the sake of clarity and to further an understanding of the invention, the terminology pertaining to semiconductor fabrication is retained in disclosing the invention in the context of the illustrated embodiments.

The illustrated portion of the process flow 100 includes two stations 105, each station 105 including a computing device 110 communicating with a process tool 115. The stations 105 communicate with one another over communications links 120. In the illustrated embodiment, the computing devices 110 and the communications links 120 comprise a portion of a larger computing system, e.g., a network 125. The process tools 115 in FIG. 1 are processing lots 130 of wafers 135 that will eventually become integrated circuit devices. The process flow 100 also includes portions of a MES and an automated materials handling system ("AMHS"), neither of which is shown for the sake of clarity, and other integrated factory controls. The AMHS "handles" the lots 130 and facilitates their transport from one station 105 to another, as well as other locations in the process flow 100.

As mentioned above, the computing devices 110 may be part of a larger computing system 125 by a connection over the communications links 120. Exemplary computing systems in such an implementation would include local area networks ("LANs"), wide area networks ("WANs"), system area networks ("SANs"), intranets, or even the Internet. The computing system 125 employs a networked client/server architecture, but alternative embodiments may employ a peer-to-peer architecture. Thus, in some alternative embodiments, the computing devices 110 may communicate directly with one another. The communications links 120 may be wireless, coaxial cable, optical fiber, or twisted wire pair links, for example. The computing system 125, in embodiments employing one, and the communications links 120 will be implementation specific and may be implemented in any suitable manner known to the art. The computing system 125 may employ any suitable communications protocol known to the art, e.g., Transmission Control Protocol/Internet Protocol ("TCP/IP").

FIG. 2 depicts selected portions of the hardware and software architectures of the computing devices 110. Some aspects of the hardware and software architecture (e.g., the individual cards, the basic input/output system ("BIOS"), input/output drivers, etc.) are not shown. These aspects are omitted for the sake of clarity, and so as not to obscure the present invention. As will be appreciated by those of ordinary skill in the art having the benefit of this disclosure, however, the software and hardware architectures of the computing devices 110 will include many such routine features.

In the illustrated embodiment, the computing device 110 is a workstation, employing a UNIX-based operating system 200, but the invention is not so limited. The computing device 110 may be implemented in virtually any type of electronic computing device such as a notebook computer, a desktop computer, a mini-computer, a mainframe computer, or a supercomputer. The computing device 110 may even be, in some alternative embodiments, a processor or controller embedded in the process tool 115. The invention also is not limited to UNIX-based operating systems. Alternative operating systems (e.g., Windows™-, Linux™-, or disk operating system ("DOS")-based) may also be employed. The invention is not limited by the particular implementation of such features in the computing device 110.

The computing device 110 also includes a processor 205 communicating with storage 210 over a bus system 215. The storage 210 typically includes at least a hard disk (not shown) and random access memory ("RAM") (also not shown). The computing device 110 may also, in some embodiments, include removable storage such as an optical disk 230, or a floppy electromagnetic disk 235, or some other form, such as a magnetic tape (not shown) or a zip disk (not shown). The computing device 110 includes a monitor 240, keyboard 245, and a mouse 250, which together, along with their associated user interface software 255 comprise a user interface 260. The user interface 260 in the illustrated embodiment is a graphical user interface ("GUI"), although this is not necessary to the practice of the invention.

Each computing device 110 includes, in the illustrated embodiment, a software agent 265 residing in the storage 210. Note that the software agents 265 may reside in the process flow 100 in places other than the computing devices 110. The situs of the software agent 265 is not material to the practice of the invention. Note also that, since the situs of the software agents 265 is not material, some computing devices 110 may have multiple software agents 265 residing thereon while other computing devices 110 may not have any. Thus, there need not be a one-to-one correspondence between the computing devices 100 and the process tools 115. Software component(s) 270, 280 of an automated MES, such as WORKSTREAM™, and of an AMHS, respectively, also reside on at least one computing device 110. As with the software agent(s) 265, the software components 270, 280 may reside anywhere within the process flow 100.

Referring now to FIG. 1 and FIG. 2, the software agents 265 each represent some "manufacturing domain entity," e.g., a lot 130, a process tool 115, a resource, a PM, or a Qual. A process tool 115 may be a fabrication tool used to fabricate some portion of the wafers 135, i.e., layer, pattern, dope, or heat treat the wafers 135. Or, the process tool 115 may be a metrology tool used to evaluate the performance of various parts of the process flow 100. The software agents 265, collectively, are responsible for efficiently scheduling and controlling the lots 130 of wafers 135 through the fabrication process. In furtherance of these objectives, the software agents 265 interface with the software components 270, 280 of the MES and AMHS, respectively, and are integrated with other existing factory control systems (not shown). The software agents 265, where appropriate, also interface with the process tools 115 and other equipment through a software implemented "equipment interface" ("EI") (not shown). As will be apparent to those skilled in the art having the benefit of this disclosure, the manner in which this interface and integration occurs is implementation specific, depending upon the makeup and configuration of the MES, the AMHS, and the other factory control systems.

Of particular interest to the present invention, the software agents 265 reactively schedule, initiate, and execute activities on behalf of their respective manufacturing domain entities. In the illustrated embodiment, the software agents 265 also proactively schedule activities. Collectively, the software agents 265, among other things, schedule ahead for each lot 130 one or more operations on a specific qualified process tool 115, including transports and required resources, as discussed further below. This includes making optimizing decisions such as running an incomplete batch, as opposed to waiting for an approaching lot 130, and scheduling opportunistic preventive maintenance ("PM") procedures or qualification tests ("Quals") to meet specifications. The software agents 265 schedule and initiate activities such as lot transport and processing; perform MES transactions; monitor processing and transport; and react to unscheduled activities or deviations from scheduled activities. Furthermore, in the illustrated embodiment, the software agents 265 are configurable in a manner that allows a user to influence their behavior in order to tune the performance of the process flow 100.

In the illustrated embodiment, the scheduling agents 265 are typed by the manufacturing domain entities they represent. There may be many different types of scheduling agents 265, depending on the implementations. The principle types of scheduling agents 265 in the illustrated embodiment, shown in FIG. 3, include:

a Lot Scheduling Agent ("LSA") 305 that schedules activities on behalf of lots 130 of wafers 135;
a Machine Scheduling Agent ("MSA") 310 that schedules activities on behalf of process tools 115;
a PM Scheduling Agent ("PMSA") 315 that schedules activities on behalf of PMs and Quals (not shown); and
a Resource Scheduling Agent ("RSA") 320 that schedules activities on behalf of resources (not shown).
However, other types may be employed in addition to, or in lieu of, those shown. The roles and functions of each of these of scheduling agents 265 in the illustrated embodiment will be more fully discussed below.

Some of these activities are scheduled reactively, i.e., in response to events occurring in, e.g., the process flow 100, in accordance with the present invention. In one particular embodiment, this includes:

detecting an occurrence of a predetermined event in a process flow, e.g., the process flow 100;
notifying a subscribing software scheduling agent, e.g., the LSA 305, the MSA 310, the PMSA 315, or the RSA 320, of the occurrence; and
reactively scheduling an action responsive to the detection of the predetermined event.
The predetermined event and the reactively scheduled action will be implementation specific. Several exemplary events and reactively scheduled actions are discussed further below.

Note that this type of reactive scheduling implies a knowledge that such events are occurring within the process flow 100. To this end, the software agents 265 respond to additional software components, not shown, known as "publishers" (or, "notifiers") and "subscribers." Agents create listeners which subscribe to one or more notifiers. Notifiers "publish" events to their subscribing listeners when changes occur within the factory. Listeners, in turn, call their subscribing software agent 265. For example, when a MSA is created, the agent will create a machine listener that subscribes to specific machine events. The MSA is interested in receiving any changes that occur to a particular machine. For example, if the availability of the machine changes, the publisher will publish the event to all of its listeners. The machine listener will then notify the subscribing MSA about the event. The subscribing MSA will then react appropriately.

More particularly, when the software agents 265 are created, they create listeners and subscribe to published events by adding the listeners to the event publisher. Listeners enable the software agents 265 to react to events in the process flow 100 in an appropriate manner. Table 1, below, lists the relevant software agents 265 employed in the illustrated embodiment, the listeners they create, and a description of their function. Note that the use of publishers and subscribers via listeners and notifiers in this manner is known to the art, and any suitable technique may be employed.

TABLE 1

Software Agents and Associated Listeners

Software Agent	Associated Listeners	Reason for Subscribing
RSA (e.g., a	Equipment Event	Listens to events from the Equip-
resource load-	Listener	ment Interface. Events may include
ing agent)		loading started, charging started,
		loading completed, charging
		completed, etc.
	Machine Listener	Listens to MES events that occur
		on the machine. For example, it
		listens when a machine is not
		available and reacts appropriately.
	Process Operation	Listens to changes within a process
	Listener	operation since it might change the
		processing capability of a machine.
	Process Listener	Listens to changes within a process
		since it might change the process-
		ing capability of a machine.
	Alarm Listener	Listens to alarms that have been set
		at start or end times for scheduled
		activities.
	Schedule Advertise-	Listens to "advertised" time slots
	ment Listener	for scheduled appointments that
		have not started.
	Appointment State	Listens to any corresponding
	Change Listener	appointments on scheduling
		calendars of other agents that
		might affect its calendar.
LSA	Alarm Listener	Listens to alarms that have been
		set at start or end times for
		scheduled activities.
	Lot Listener	Listens to MES events that occur
		on the lot, such as product change,
		priority change, wafer count, and
		so on.
	AMHS Listener	Listens to changes in the location
		of the lot of represented by the
		LSA.
	Appointment State	Listens to any corresponding
	Change Listener	appointments on scheduling
		calendars of other agents that
		might affect its calendar.
MSA	Alarm Listener	Listens to alarms that have been set
		at start or end times for scheduled
		activities.
	Process Operation	Listens to changes within a process
	Listener	operation since it might change the
		processing capability of a machine.
	Machine Listener	Listens to MES events occurring
		on the machine. For example, it
		listens when a machine is not
		available.
	Appointment State	Listens to any corresponding
	Change Listener	appointments on scheduling
		calendars of other agents that
		might affect its calendar.
	Chamber Listener	Listens to MES events that occur at
		chamber level, such as downtime,
		PM, or Quals.
	Process Listener	Listens to changes within a process
		since it might change the process-
		ing capability of a machine.
	Equipment Event	Listens to events from the Equip-
	Listener	ment Interface. Events may include
		carrier arriving at the machine port,
		processing started, processing near
		complete, carrier departed, etc.
PM Scheduling	Chamber Listener	Listens to MES events that occur at
Agent		chamber level, such as downtime,
("PMSA")		PM, or Quals.
	Machine Listener	Listens to MES events that occur
		on the machine. For example, it
		listens when a machine is not
		available.
	Qual Collection	Listens to any new Quals or
	Listener	deleted Quals.
	PM Collection	Listens for any new PMs or deleted
	Listener	PMs.
	Appointment State	Tracks changes to any appoint-
	Change Listener	ments that might affect his
		calendar.

As is evident from Table 1, the software agents 265 listed therein listen to appointment changes that might affect their calendar. Consider, for example, FIG. 5 (discussed in more detail below) in conjunction with Table 1. FIG. 5 illustrates different appointments (SETUP₁, LOT₁, MOVE₁, TOOL₁, PM, QUAL, etc.) that are contained within the calendars for each of several agents (the MSA for TOOL₁, the LSA for LOT₁, a PMSA, and a RSA). FIG. 5 also illustrates corresponding appointments between those calendars. Fe: example, the MSA calendar contains a processing appointment LOT₁ that corresponds with the processing appointment TOOL₁on the LSA calendar. These two appointments are actually for the same event (i.e., the processing of LOT₁on TOOL₁) made by two different entities (i.e., the MSA and the LSA, respectively) for two different entities (i.e., the lot LOT₁and the processing tool TOOL₁).

Referring now to both FIG. 3 and FIG. 5, when corresponding appointments (e.g., LOT₁, TOOL₁) are created, the appointments themselves may contain a collection of listeners, e.g., the listeners 356, 358 in FIG. 3. Listeners are added to the appointment when other software agents 265 want to be notified that the appointment has changed. In this case, the lot processing appointment LOT₁ on the MSA calendar 370 contains a listener 356 that notifies the LSA 305 through a notifier 354 when the processing appointment LOT₁changes. On the other hand, the lot appointment TOOL₁contains a listener 358 that notifies the MSA 310 through a notifier 352 when it changes. If the MSA 310 changes the processing appointment LOT₁, the LSA 305 will be notified of the appointment change and it will modify the appointment TOOL₁accordingly. Thus, listeners enable the software agents 265 to synchronize the corresponding appointments. Also, the software agents 265 can schedule reactively to such predetermined events when appropriate and can then keep their calendars updated as changes are instituted by other software agents 265.

When the software agents 265 react to appointment changes, they carefully manipulate the corresponding appointments. In some cases, it would be inappropriate for two software agents 265 to manipulate their respective corresponding appointments at the same time. Thus, a single software agent 265 is responsible for manipulating its respective corresponding appointment, which will then prompt the software agent 265 of the corresponding appointment to manipulate its respective corresponding appointment. For example, in FIG. 5, the LSA 305 contains a move appointment MOVE₁ followed by the lot processing appointment TOOL₁. If the end time for the move appointment MOVE₁arrives but the appointment is not finished, an alarm listener notifies the LSA 305. ("Alarms" are one type of event listened for, and are discussed further below.) The LSA 305 then expands the duration of the move appointment MOVE₁by a configurable amount of time, but also shifts the lot processing appointment TOOL₁to accommodate the expansion of the move appointment MOVE₁.

At the same time, the alarm listener for the MSA 310 will notify it that the start of the lot processing appointment TOOL₁ has arrived. Since the LSA 305 can best determine when the lot LOT₁should arrive at the process tool 115, the LSA 305 shifts the start time of the lot processing appointment TOOL₁after expanding the move appointment. The MSA 310 will wait for its appointment state change listener to notify it of the shift to the lot processing appointment, will find its counterpart lot processing appointment, and shift it accordingly. In this circumstance, the MSA 310 will ignore its own start time alarm. Although not shown, the lot 130, process tool 115, resources, and PMs and Quals all have corresponding "processing" agents, also not shown, that are notified by the scheduling agents when significant events occur that may require processing.

In furtherance of their proactive and reactive scheduling duties, the software agents 265 maintain calendars, such as the calendar conceptually illustrated in FIG. 4, of scheduled "appointments." FIG. 4 conceptually illustrates a calendar containing information concerning appointments for, e.g., a process tool 115 for a number of lots 130. An "appointment" is a time period certain in which the process tool 115 has obligated itself to perform the process operation, and is defined by an Appointment Start Time ("TS") and an Appointment End Time ("TE"). In the illustrated embodiment, the appointments are booked within "commitment windows" ("CW"), or time windows defined by an Earliest Start Time for processing ("EST") and a Latest Delivery Time ("LDT_p"). The client lot 130 commits to arrive at the process tool 115 no later than the EST and the process tool 115 commits to complete the processing no later than the LDT. Note, however, that the use of commitment windows are not necessary to the practice of the invention.

In FIG. 4, the process tool 115 has booked appointments APP₁-APP₄ for lots Lot₁-Lot₄, respectively. Thus, the calendaring information for Lot₁-Lot₄is as follows:

Lot₁: APP₁[t₁₀, t₁₂], CW₁[t₈, t₁₄]
Lot₂: APP₂[t₁₃, t₁₅], CW₂[t₉, t₁₆]
Lot₃: APP₃[t₅, t₇], CW₃[t₂, t₁₁]
Lot₄: APP₄[t₃, t₄], CW₄[t₁, t₆]

Note that, in the illustrated embodiment, several of the commitment windows overlap, but none of the appointments overlap. Appointments may be shifted within their commitment window, so long as they do not overlap other appointments, or may be expanded, shrunk, canceled and rescheduled as is discussed more fully below. However, in some embodiments, parts of the appointments may overlap.

Thus, returning to FIG. 3, appointments, e.g., the processing appointment 375, are proactively booked on calendars, e.g., the calendars 385, 370, maintained by each scheduling agent, e.g., the scheduling agents 305, 310. Note, however, that not all appointments are processing appointments. Whenever the processing appointment 375 is booked, the LSA 305 schedules move appointments for moving the lots 130 to the location of the newly booked processing appointment 375. For instance, referring to FIG. 1 again, assume the lots 130 processing on the first process tool 115 exits from a port 140 and needs to arrive at the port 145 of the second process tool 115 for the scheduled processing appointment 375. Each LSA 305 schedules the appointments for the lot 130 to transit between the source and destination locations, e.g., the port 140 of the first process tool 115 and the port 145 of the second process tool 115.

FIG. 5 conceptually illustrates three related calendars maintained for three different types of entities—a lot 130, a process tool 115, and a preventive maintenance ("PM")—on which different types of appointments are booked. In the illustration of FIG. 5, as opposed to the illustration of FIG. 4, all appointments for a given calendar are collapsed onto a single timeline. The commitment windows for each appointment are omitted to facilitate this collapse and to keep from unduly cluttering the illustration. More particularly, FIG. 5 illustrates:

a calendar for a process tool TOOL₁ maintained by a MSA for the process tool TOOL₁, including appointments booked for setups (e.g., SETUP₁, SETUP₂);
lot processing appointments (e.g., LOT₁, LOT₂, LOT₃); PMs (e.g., PM); and
Quals (e.g., QUAL);
a calendar for a lot LOT₁ maintained by a LSA for the lot LOT₁on which are booked appointments for moves (e.g., MOVE₁, MOVE₂, MOVE₃, MOVE₄, MOVE₅) and lot processing appointments (e.g., TOOL₁, TOOL₂); and
a calendar for a PM maintained by a PMSA on which are booked appointments for PMs (e.g., PM), and Quals (e.g., QUAL).
Still other types of appointments may be booked. For instance, if the process tool TOOL₁ goes down, i.e., is no longer available for processing, a "downtime appointment" may be booked on its calendar to represent the expected repair time. Note that each of these appointments in the calendar of FIG. 5 is for an event that, in the first instance, the software agents 265 proactively schedule according to the manufacturing domain entity they represent.

An appointment, e.g., the processing appointment 375 in FIG. 3, exists in one of several "states", or have a certain "status," at any given time. In the illustrated embodiment, the status may be:

tentative—the appointment has been created, but not booked (which is discussed further below);
unready—the tentative appointment has been booked, but is not ready for execution;
ready—the lot 130 involved in the appointment has arrived at the process tool 115 for which it is booked;
active—the start time for the appointment has arrived and all participants are ready;
active PM/Qual—the start time for a following Qual portion of a PM appointment has arrived;
processing—the scheduled activity has started, i.e., the start command has been confirmed by the process tool 115, or the PM or Qual has started;
processing PM/Qual—the follow-up Qual portion of a PM has started;
near complete—the appointment is nearing completion as defined by predetermined parameters (e.g., processing time remaining, wafer count);
complete—processing is completed;
canceled—booked appointment is removed from a calendar before it enters the processing status; and
aborted—appointment was stopped during processing in a processing status.
A tentative appointment remains tentative until it is booked, whereupon it enters the unready status. The appointment is unready until the lot 130 arrives at the process tool 115. The appointment is then ready until the start time for the appointment arrives. The appointment then becomes active (i.e., the appointment commences) until the process tool 115 confirms it has started processing. Once the appointment is processing, it retains that status until it nears completion and then is complete. If the appointment is removed from the calendar before entering the processing state, it is "canceled" and removed from the system. Once in the processing status, the appointment is "aborted" if halted. A completed appointment or an aborted appointment retains this status until it is removed from the system.

However, in accordance with the present invention, the software agents 265 also reactively schedule events for their respective manufacturing domain entities resulting from developments in the process flow 100. Typically, reactive scheduling by the software agents 265 effects changes to appointments that were, in the first instance, proactively scheduled. However, this is not necessary to the practice of the invention. For instance, in one particular embodiment, the software agents 265 schedule activities in reaction to a machine failure which causes the machine to stop processing and requires a period of downtime in order to repair the machine. There usually would not be any proactively scheduled appointment for such an event since a machine failure usually cannot be predicted in advance.

More particularly, the software agents 265 usually react to different events that occur within the process flow 100. These events are identified beforehand, i.e., are "predetermined," so that appropriate activities in reaction to those events can be defined. The appropriate actions will depend on a number of factors including not only the type of manufacturing domain involved, but also the type of event that is involved. The predetermined events are categorized, in the illustrated embodiment, as one of three types: appointment state change, a factory state change, or an alarm event.

Appointment state changes usually occur when a software agent 265, e.g., the scheduling agents 305, 310 change an appointment, e.g., the processing appointment 375. A software agent 265 may change the status of the appointment, expand or shrink the appointment, cancel the appointment, shift the appointment, or perform other manipulations to the calendar or appointments on the calendar. When an appointment is changed, the appropriate agents 265 react to the change. For example, the MSA 310 may expand the scheduled duration of the appointment 375 on its calendar 370 due to the appointment 375 running late. The LSA 305 reacts to that change by expanding the corresponding appointment 375 on its calendar 385 to keep the appointments 375 synchronized across the two calendars 370, 385. Appointment state changes may include, for instance, appointment cancellations, appointment expansions, appointment shrinkage, appointment aborts, appointments changing status, appointments shifting, and commitment window updates.

Factory state changes usually occur when the state of the factory, e.g., the process flow 100, changes. Factory state change events may originate from the MES 270 (shown in FIG. 2), the AMHS 280 (also shown in FIG. 2), or from the Equipment Interface ("EI", not shown) for the process tools 115. Factory state changes may include lot due date changes, a lot being put on hold, changing the process or process operation of a lot, a lot's location changing, a carrier arriving at a machine port, etc. For every factory state change that is a "predetermined event," the software agents 265 react accordingly. Exemplary factory state changes might include a downtime occurrence; a machine becoming available; a PM/Qual being detected; a chamber going down; a lot departing a machine; a move completed; and a wafer completed.

Alarm events occur, in this particular embodiment, when a specific alarm has expired. Agents react when an alarm event is received—for example, when the appointment end time has arrived for a lot appointment. If the machine agent does not receive notification that the appointment has ended, the machine agent will expand the appointment based on a configurable percentage of the appointment's total duration. Once the appointment is expanded, the machine agent will set a new alarm for the new, predicted end time of the appointment. An alarm event might be, for instance, an alarm firing for an appointment start time or an alarm firing for an appointment end time.

Note that some events are unplanned, or unexpected. For instance, there is no reliable way to actually know when a machine or chamber goes down unless it is going down for a scheduled PM or a Qual period. Some of these events are expected. For instance, the time at which a lot 130 arrives at the port 145 of the process tool 115 should be known if it arrives on time since the move was scheduled. Some embodiments may therefore choose not to schedule reactively to such an event, instead preferring to schedule proactively on the assumption the schedule will be met and scheduling reactively only if the schedule is not met. Note that other embodiments may schedule reactively to events not listed either in addition to or in lieu of those set forth herein.

The reactive scheduling performed upon the occurrence of any particular event will depend on the nature of the event and, to some degree, upon the particular implementation. Generally speaking, the reactive scheduling typically includes changing appointments, e.g., the appointment 375 in FIG. 3, previously scheduled and booked. Booked processing appointments and PM/Qual appointments may be shifted, expanded, aborted, shrunk, canceled, and re-scheduled. Move and setup appointments are modified as needed at the time lot processing appointments are modified. In the illustrated embodiment, these appointment modifications are performed by the LSA 305 or the MSA 310.

For example, booked processing appointments may be shifted, which may cause booked move appointments to be canceled, aborted, or rescheduled. Appointments are viewed as "beads on a string". Existing appointments are permitted to slide backward or forward in time (i.e., "right" or "left" in FIG. 4 and FIG. 5) within their respective commitment windows as desired to accommodate changes in scheduling. In the illustrated embodiment, to simplify the logic, appointments are not permitted to shift past the next appointment in either direction.

Consider the circumstance where a lot processing appointment for a lot 130 completes earlier than expected. This provides an opportunity for the MSA 310 to reactively schedule what is known as an "early start." Because the MSA 310 in FIG. 3 is idle, the MSA 310 will attempt to shift the next appointment to an earlier start time and start it immediately. When the lot 130 completes the processing appointment early, the MSA 310 reacts by shifting subsequent scheduled appointments earlier in time to take advantage of the early start opportunity. The LSA 305 will react differently to the event of the lot processing completing early.

This instance is shown in FIG. 6A, wherein the current time t_c falls within the commitment window CW₁for the next appointment APP₁. The next appointment APP₁is then shifted left, or earlier in time, so that its processing can begin immediately. If the next booked appointment cannot be shifted to start at the current time, the MSA 310 will search for any other booked appointments that may have commitment windows starting at the current time or earlier. If one of these booked appointments can be moved to start immediately without causing cancellation of any other booked appointments, the booked appointment will be moved in a "jump over" fashion and other booked appointments will be shifted as required. This scenario is shown in FIG. 6B, wherein the current time t_cat which the provider is idle is outside the commitment window CW₁for the next booked appointment APP₁, but falls within the commitment window CW₃of the third booked appointment APP₃. Hence, the third appointment APP₃performs a "jump over" operation, jumping over appointments APP₁and APP₂and appointment APP₁is shifted right to a later start time immediately following appointment APP₃.

In either situation, the LSAs 305 for the affected lots 130 are notified by that their appointments have been changed. The difference in start times and end times may also change the appropriateness of scheduled moves. For instance, if a booked appointment is shifted left, the earlier start time means the lot 130 must arrive earlier than may be provided for by the currently scheduled moves. Conversely, a later start time means the lot 130 should move later. In either circumstance, modified moves may be appropriate to achieve the correct arrival time for the lot 130.

Consider also the circumstance where the software agents 265 reactively schedule because the duration of a current appointment, or an appointment immediately preceding it, is longer than expected. When the LSA 305 and MSA 310 book appointments, they set an "end-time alarm" (not shown) that notifies them when the appointment is scheduled to be completed. When the task is completed, the scheduling agents 305, 310 are notified and these alarms are canceled. Thus, if the alarm fires, then the scheduling agents 305, 310 know the appointment did not complete at the scheduled time, and that the appointment needs to be expanded.

FIG. 7A and FIG. 7B illustrate two such situations. The timelines for the appointments in each have been collapsed and the commitment windows are omitted as was the case for the calendars in FIG. 5. In FIG. 7A, the move MOVE₃ had a longer duration than was expected, and so the moves MOVE₄, MOVE₅and the appointment APP₂were shifted later in time to accommodate this longer duration. In FIG. 7B, the appointment APP₃took longer than was expected, and so the appointments APP₄and APP₅were shifted later in time. Note that in both FIG. 7A and FIG. 7B, the illustrated changes necessarily imply that, in ooth circumstances, the commitment windows for the changed appointments were wide enough to accommodate the changes. Otherwise, some appointments would have to be canceled.

As can be seen from these two examples, the reactive scheduling will vary according to the circumstance. In general, in the illustrated embodiment, the following scheduling activities may occur responsive to a predetermined event:

aborting a scheduled appointment in progress;
canceling a scheduled appointment before it begins;
scheduling a new appointment;
starting a scheduled appointment;
expanding the duration of a scheduled appointment;
shrinking the duration of a scheduled appointment;
shifting a scheduled appointment to an earlier or later time;
changing a commitment window;
changing an appointment attribute (e.g., transport start time, remaining transport time, etc.);
setting an alarm;
canceling an alarm; and
changing the status of an appointment.
The "predetermined events" provoking such reactive scheduling may include, for an appointment state change:
canceling an appointment;
expanding an appointment;
shrinking an appointment;
aborting an appointment;
an appointment changing status;
shifting an appointment;
an unexpected carrier arrival;
a transport time update;
a load time update;
an unload time update;
a lot joining a batch;
a lot leaving a batch;
canceling a lot from a batch; and
updating a commitment window.
For a factory state change, the predetermined event might be, for example:
detection of downtime;
a machine becoming available;
a PM/Qual being detected;
a chamber going down or coming up;
a change in machine capabilities;
a change in machine types;
addition of a process;
addition of a process operation;
a lot process changed;
a lot placed on hold;
a lot relesed from hold;
a lot priority changed;
a lot due date changed;
a lot wafer count changed;
a lot process operation changed, and
a lot departing from or arriving at a machine.
And, for an alarm event, the predetermined event might be:
an alarm firing for an appointment start time; and
an alarm firing for an appointment end time.
Note that these lists are not exhaustive, but illustrative only. The identity of predetermined events will be implementation-specific, and so may vary among embodiments. Typically, depending on the event provoking the reactive scheduling, these activities will be employed in combination, or in the alternative, conditionally. Tables 2-5 list the predetermined events, their type, and their reactive scheduling activities for machine, lot, PM, and resource scheduling agents, respectively, for one particular implementation of the present invention.

Tables 2, Table 3, and Table 5 refer one or more of load/unload operations and appointments and charge/discharge operations and appointments. As will be appreciated by those skilled in the art having the benefit of this disclosure, some process tools 115 perform lot batch process operations in which multiple lots 130 are simultaneously processed in a batch. Some of these process tools 115 use load, charge, discharge and unload steps. For instance, a process tool 115 may first load all the batch participants, i.e., lots 130, from the tool I/O ports (not shown) to the tool internal stocker (also not shown). Usually this type of process tool 115 has multiple I/O ports, and the load/unload operations are also performed in batches. After all the batch participants are loaded, the process tool 115 performs a batch charge operation to move the batch participants from the internal stocker into, e.g., a furnace tube (not shown) before the processing can actually begin. After the process tool 115 completes the batch process operation, it discharges the batch participants, e.g., from the furnace tube back into the internal stocker. Finally when the lots 130 are ready to be moved to the tool I/O ports, a sequence of batch unload operations is performed.

Table 2 also refers to appointments that are "locked." To help prevent undesirable appointment shifting, the illustrated embodiment employs an appointment locking mechanism. Generally speaking, when a lot 130 starts its final move from a source location to a process tool 115, it is undesirable to have a new appointment jumping in front of it by canceling or shifting that appointment to the right, or later in time. To prevent this from occurring, the MSA "locks" the lot processing appointment when the lot 130 starts its final move. Note that locked appointments nevertheless sometimes do need to be shifted. For instance, assume two appointments are booked on the calendar for a particular process tool 115, and the first one is processing while the lot 130 for the second one has started the final move to the process tool 115. The second appointment is locked because it is in its "final" move to the process tool 115. If the first appointment runs long and must be expanded, the second one must first be shifted to permit the first one to expand. Thus, the locked second appointment must be shifted even though this is generally undesirable. In general, however, appointments may be "locked" in certain circumstances to prevent them from being shifted or canceled.

TABLE 2

Reactive Scheduling Activities for MSAs

Event	Event Type	Reactive Scheduling Activities
Downtime	Factory State	A downtime event may indicate the machine
Detected	Change	is currently not available for processing or
	(MES)	that an error has occurred during processing.
		If the MSA detects that the machine is not
		currently available for processing, the MSA
		will abort and shrink any lot processing
		appointment that is processing. It will then
		book a downtime appointment after the
		aborted lot processing appointment or after
		the unload appointment. If the downtime
		event occurred due to an error during
		processing, the MSA will book a downtime
		appointment after the lot processing
		appointment that is processing or the unload
		appointment. Booked processing
		appointments overlapping the downtime
		appointment are shifted later in time, if
		possible, or are otherwise cancelled.
Machine	Factory State	Any active PM, QUAL, or downtime
Available	Change	appointments are completed. The next
Detected	(MES)	appointment on the machine's calendar is
		then shifted and started, if possible.
PM/Qual	Factory State	A PM/Qual appointment is booked after any
Detected	Change	active appointments. Any booked
	(MES)	appointments overlapping the PM/Qual
		appointment are shifted after the PM/Qual
		appointment. If any overlapping booked
		appointment cannot shift, it is cancelled.
Chamber	Factory State	All unready appointments for the machine or
Down	Change	chamber that has not started are canceled.
Detected	(MES)
Chamber Up	Factory State	The duration for any appointment is
Detected	Change	shrunken to the expected completion time
	(MES)	based on the new throughput rate and shifted
		to the right, or later in time, if possible.
Lot Not At a	Alarm State	If the lot has "reserved" a port with the
Port At a	Change	machine, the MSA will wait until the LSA
Scheduled		expands the move appointment. The
Start Time		expansion of the move appointment will
		cause the LSA to shift the lot appointment to
		the right. The MSA will then react
		appropriately to the shifting of the lot
		appointment. If the lot has not reserved the
		port, the appointment is cancelled.
Lot Arrived	Factory State	If the lot arrived at the right location, the
at Machine	Change (EI)	MSA will make the appointment active if it
Port		is not a participant of a batch appointment. If
		the appointment is a participant of a batch
		appointment, the MSA will make the
		appointment ready. If the machine is idle and
		the appointment is active, the MSA will start
		processing the appointment. (Note: a
		participant of a batch appointment is made
		active when all of the participants have
		arrived at the machine.) If the lot arrived at
		the right machine but the wrong port, the
		MSA will check to see if a different lot
		reserved the port. If a different lot reserved
		the port, the MSA will assign that lot the
		next available port. If the appointment for
		the arriving lot is active, the MSA will start
		processing the appointment. If the lot arrived
		at the wrong machine, the MSA will check
		to see if a different lot reserved the port. If a
		different lot reserved the port, the MSA will
		assign that lot the next available port. The
		machine will then book an appointment for
		the lot just arrived. Any overlapping
		appointments will be shifted to a later time.
		If an overlapping appointment cannot shift
		later in time, it will be cancelled.
Lot Process-	Alarm State	If a lot processing appointment is running
ing Appoint-	Change	late, it is expanded and any overlapping
ment Run-		booked appointments are shifted to the right,
ning Late		or later in time. If any overlapping booked
		appointment cannot shift right and the
		appointment is not locked, it is cancelled. If
		the appointment is locked and cannot shift
		right, the appointment's commitment
		window will be expanded to allow the shift
		to occur.
Lot Process-	Factory State	If a lot processing appointment completes
ing Complet-	Change (EI)	earlier than expected, the appointment is
ing Early		shrunk and completed and, if possible, the
		next appointment is shifted earlier in time. If
		the next appointment can shift to the current
		time, it will start that appointment.
Lot Process-	Factory State	The MSA calculates the remaining
ing Near	Change (EI)	processing time for the lot. If it is going to
Complete		finish early, the appointment is shrunken to
Detected		the new end time and any following
		appointments are shifted left, or earlier in
		time. If it is going to finish late, the
		appointment is expanded to the new end time
		and any overlapping appointment are shifted
		to a later time or cancelled.
Lot	Appointment	If processing or near complete, the
Appointment	State Change	appointment is aborted or, if unready, simply
Cancelled		canceled. Upon cancellation of an
		appointment, the next appointment is shifted
		earlier in time, if possible, to reduce any
		gaps between appointments.
Lot Depart-	Factory State	If the lot was still processing at the time of
ing Machine	Change (EI)	its departure, the appointment is aborted and
Port		the end time shifted earlier in time. The next
		appointment is shifted earlier as much as
		possible.
Shift	Appointment	The appointment is shifted right. If it cannot
Appointment	State Change	be shifted right, it is canceled, unless it is
Right		locked. If it is locked, any appointment
		blocking the right shift are cancelled

Table 3 refers to "feeder operations." In a partially automated fab, only a portion of the process operations may be scheduled and controlled by the software agents 265. Thus, only a subset of the process tools 115 in the fab are under the control of the software agents 265 and the fab is not fully under the control of this system. Those process operations controlled by the software agents 265 are called "control process operations." Immediately before each control process operation, a sequence of "feeder" operations can be derived from a configurable percentage of the process time of the controlled process operation. Feeder appointments are used in determining the earliest start time for an appointment being scheduled ahead. More particularly, feeder appointments are used when a LSA is scheduling ahead and the time has not yet arrived for scheduling the feeder operation with an actual process tool 115. Feeder appointments are used to represent processing activities for those feeder operations with the duration equal to the cycle time of the respective feeder operations.

Table 3 also refers to "maxMove" appointments. For a feeder operation, the specific process tool 115 that will perform the final feeder operation is not known until the lot 130 begins processing at the final feeder operation. A "maximum move" appointment represents transport activities from the last feeder process tool 115 to a controlled process tool 115. In one embodiment, the duration of the maximum move appointment is derived by the worst case transport time between the last feeder process tool station 105 and the controlled process tool station 105. When the last feeder appointment is activated, the actual process tool 115 performing the last feeder operation is known, and thus the maximum move appointment will be replaced by a move appointment or a sequence of move appointments.

Table 3 furthermore refers to a "bid request." In the illustrated embodiment, the process flow 100 employs a protocol for scheduling appointments that begins with a "bid request." The LSA 305 publishes a "request bid" message to a capable MSA 310. The MSA 310 submits one or more bids to the LSA 305. The LSA 305 selects one from among several such bids, which typically results in one or more "appointments" associated with performing the operation the LSA 305 is seeking for its lot 130 of wafers 135. Note, however, that other protocols may be employed in which there is no "bid request." Thus, the bid request is an implementation specific feature that may not be found in all embodiments.

TABLE 3

Reactive Scheduling Activities for LSAs

Event	Event Type	Reactive Scheduling Activities
Appointment End	Alarm Event	The alarm indicates that the scheduled
Time Alarm Fired		end time of the move appointment has
For Move		arrived. The LSA determines if the
Appointment		move appointment should be expanded.
		If the move originates from a machine
		port, move appointment expansion is
		always permitted to clear the port.
		Otherwise, the move appointment is
		expanded a percentage (i.e., 25%) of
		the originally scheduled duration until a
		maximum expansion percentage has
		been reached (i.e., 175%). When the
		maximum expansion percentage has
		been reached, the appointment is
		aborted. If the move appointment
		is expanded, subsequent booked
		appointments are shifted later in
		time. A new end time alarm is
		then set for the expanded move
		appointment.
Appointment End	Alarm Event	The alarm indicates that the scheduled
Time Alarm Fired		end time of the feeder appointment has
For Feeder		arrived. The LSA will expand the
Appointment		appointment by a configurable
		percentage. Any subsequent feeder
		appointments (if any) will be shrunk by
		the amount that this feeder appointment
		expanded (can't shrink a feeder duration
		to be less than the process time for the
		operation). As a last resort,
		appointments after the final feeder
		appointment will be shifted to a later
		time.
Appointment	Alarm Event	This alarm indicates that the scheduled
Start Time		start time of the specified move
Arrived For		appointment has occurred. The LSA
Move		will make the appointment active if it is
Appointment		not active and the AMHS move will be
		initiated. If the appointment is the
		final move before a lot appointment,
		the LSA will ask a MSA to reserve a
		port and lock the appointment. It will
		also appropriately update the total
		transport time and remaining transport
		time. The LSA will then create an
		appointment end time alarm.
Appointment	Alarm Event	This alarm indicates that the scheduled
Start Time		start time of the specified feeder
Arrived For		appointment has occurred. The LSA
Feeder		will make the appointment active if it is
Appointment:		not active. The LSA will then create an
		appointment end time alarm.
Lot Appointment	Appointment	The LSA cancels the lot appointment
Completed		and any non-also cancel the end time
		alarm, appropriately updates the
		transport start time, and initiates the
		next appointment.
Make Lot	Appointment	The MSA initiates this change when it
Appointment	State Change	receives an equipment event stating that
Near Complete		the lot processing is near complete. The
		LSA will change the status of the
		appointment to near complete. It will
		then schedule the post control move
		appointment and invokes scheduling for
		the next process operation if
		appropriate.
Shift Lot	Appointment	The LSA will try to move the lot
Appointment Left	State Change	appointment to the left, or earlier in
		time. If it is unable to shift left, the
		system will cancel all non-active move,
		load, and unload appointments and then
		cancels the lot appointment.
Shift Load	Appointment	The LSA will try to move the load
Appointment Left	State Change	appointment to the left. If it is unable to
		shift left, the system will cancel all non-
		active move appointments, cancels
		unload/load appointments, cancels the
		lot appointment.
Shift Unload	Appointment	The LSA will try to move the unload
Appointment Left	State Change	appointment to the left. If it is unable to
		shift left, the system will cancel all non-
		active move appointments, cancels
		unload/load appointments, and cancels
		the lot appointment.
Shift Lot	Appointment	The LSA will check to see if the first
Appointment	State Change	appointment is a move appointment. If
Right		it is a move appointment and it is not
		active or on a machine or machine port,
		it will shift that move appointment to
		make it arrive at the start of the lot
		appointment or load appointment (if the
		move appointment is active, it will
		expand the end to the start of the lot
		appointment or load appointment). It
		will then shift any preceding
		appointments to the right. If the system
		is unable to shift the appointments right,
		it will cancel all non-active move
		appointments, any load/unload
		appointment, and the lot appointment.
Shift Load	Appointment	The LSA will check to see if the
Appointment	State Change	previous appointment is a move
Right		appointment. If it is a move
		appointment and it is not active or on a
		machine or machine port, it will shift
		that move appointment to make it arrive
		at the start of the load appointment (if
		the move appointment is active, it will
		expand the end to the start of the load
		appointment). It will then shift any
		preceding appointments to the right. If
		the system is unable to shift the
		appointments right, it will cancel all
		non-active move appointments, any
		load/unload appointments, and the lot
		appointment.
Shift Unload	Appointment	The LSA will shift appointments to the
Appointment	State Change	right. If the system is unable to shift the
Right		appointments right, it will cancel the lot
		appointment, which will cancel all
		move, load, and unload appointments
		association with the lot appointment.
Shrink Lot	Appointment	The LSA will shrink the lot
Appointment	State Change	appointment to the specified time and
		shift subsequent move appointments
		earlier in time.
Shrink Load	Appointment	The LSA will shrink the load
Appointment	State Change	appointment to the specified time.
Shrink Unload	Appointment	The LSA will shrink the unload
Appointment	State Change	appointment to the specified time.
Unscheduled	Factory State	If the current location of the lot is a
Move Completed	Change	machine port, then the system will
	(AMHS)	cancel all appointments except the lot
		appointment. The lot appointment will
		only be cancelled if the appointment
		was for a different machine. If the
		appointment was for a different
		machine, the LSA will cancel all
		appointments and wait for the MSA to
		invoke override scheduling. Otherwise,
		the system will determine how long it
		will take for the lot to get back to the
		next processing appointment
		destination. If the lot can still make its
		processing start time, then the system
		will reschedule the appropriate move
		appointments. If the lot is unable to
		make the start time, it will cancel all
		move, load, unload, and lot
		appointments and will initiate
		scheduling.
Update	Appointment	The LSA will update the lot
Commitment	State Change	appointment commitment window
Window For Lot		appropriately. The commitment window
Appointment		represents the lots earliest start time
		and latest delivery time for a given
		appointment. The commitment window
		is updated if an appointment is
		processing late and the new end time
		exceeds the latest delivery time of the
		appointment.
Update Load	Appointment	The LSA will update the load start time
Time For Load	State Change	and remaining load time appropriately
Appointment		on the load appointment.
Wrong Move	Appointment	If the current location of the lot is a
Completed	State Change	machine port, then the system will
		cancel all appointments except for the
		lot appointment. The lot appointment
		will only be cancelled if the
		appointment was for a different
		machine. If the appointment was for a
		different machine, the LSA will cancel
		all appointments and wait for the MSA
		to invoke override scheduling.
		Otherwise, the system will determine
		how long it will take for the lot to get
		back to the next processing appointment
		destination. If the lot can still make its
		original processing start time, then the
		system will reschedule the appropriate
		move appointments. If the lot is unable
		to make the start time, it will cancel all
		move, load, unload, and lot
		appointments and will initiate
		scheduling.
Lot Due Date	Factory State	If the lot has a processing appointment
Change	Change	active, cancel appointments after either
	(MES)	current appointment or following unload
		appointment (if present). If the
		appointment is in "near complete"
		status and the next process operation is
		not a control operation or there is no
		next operation in the process, schedule a
		move appointment after the current lot
		processing appointment. Otherwise,
		attempt to schedule the next process
		operation. If the lot has a move
		appointment active and the move is to a
		machine port destination, cancel
		appointments after the following load
		appointment (if present) and following
		lot processing appointment. Otherwise,
		cancel all appointments after the move
		appointment and reschedule the current
		process operation. If the lot has a feeder
		appointment active, cancel all
		appointments after the feeder
		appointment and reschedule the next
		process operation. If the lot has a load
		appointment active, cancel
		appointments after the following lot
		appointment or load appointment (if
		present.) If the lot has an unload
		appointment active, cancel
		appointments after the current time. If
		the next operation is not a control
		operation or there are no more
		operations, schedule a move
		appointment after the unload
		appointment. Reschedule for the next
		process operation. If no appointments
		are active, cancel all future
		appointments and reschedule current
		process operation.
Lot put on Hold	Factory State	If lot is processing, cancel appointment
	Change	after post move appointment. If lot is
	(MES)	moving to control machine port, cancel
		all appointments after the move and
		schedule a move to the nearest stocker
		as soon as the lot arrives at the machine
		port. If unload appointment is
		processing, cancel all appointments
		after and schedule post move. If feeder
		appointment is processing, shrinks and
		aborts the appointment and then cancels
		all appointments after feeder
		appointment. If load appointment is
		processing, it cancels all appointments
		after except for the unload appointment.
		It will then schedule a post move
		appointment. If the lot has a processing
		appointment active, and it is in a status
		of processing or near complete, it is
		allowed to complete. If the next
		appointment is an unload appointment,
		all subsequent appointments are
		cancelled and a move is scheduled after
		the unload. If the next appointment is a
		move appointment, it and subsequent
		appointments are cancelled and another
		move is scheduled. If there are no
		subsequent appointments, a move is
		scheduled after the processing
		appointment. If the lot appointment is
		active but not processing or complete, it
		is shrunk and aborted. If the next
		appointment is an unload appointment,
		subsequent appointments are cancelled
		and a move appointment is scheduled. If
		the next appointment is a move
		appointment, it is cancelled and another
		move appointment is scheduled. If there
		are no next appointments, a move
		appointment is scheduled. If the lot is in
		a feeder appointment, it is shrunk and
		aborted and all subsequent appointments
		cancelled. If the lot is in a load
		appointment and it is in a processing
		status, the subsequent lot processing
		appointment is cancelled. The following
		unload appointment is left and all
		subsequent appointments cancelled. A
		move appointment is scheduled after
		the unload appointment (both will later
		shift earlier in reaction to
		appointment changes initiated by the
		RSA). If the load appointment is not
		processing, it and subsequent
		appointments are cancelled and a move
		appointment is scheduled. If the lot is in
		an unload appointment, all subsequent
		appointments are cancelled and a move
		appointment is scheduled after the
		unload appointment. If the lot is in a
		move appointment and the move has
		started, all subsequent appointments
		are cancelled. If the move is to a
		machine port, a move is scheduled to
		subsequently transport the lot off the
		machine port. If the lot is on a move
		appointment that has not started, the
		move appointment is aborted and all
		subsequent appointments cancelled.
Process Changed	Factory State	If the lot has a processing appointment
	Change	active, cancel appointments after either
	(MES)	current appointment or following unload
		appointment (if present). If the
		appointment is in "near complete"
		status and the next process operation is
		not a control operation or there is no
		next operation in the process, schedule a
		move appointment after the current lot
		processing appointment. If the
		appointment is near complete and the
		next operation is a control operation,
		attempt to schedule the next process
		operation. If the lot has a move
		appointment active and the move is to a
		machine port destination, cancel
		appointments after the following load
		and unload appointments (if present)
		and following lot processing
		appointment. Otherwise, cancel all
		appointments after the move
		appointment and reschedule the current
		process operation. If the lot has a feeder
		appointment active, cancel all
		appointments after the feeder
		appointment and reschedule the next
		process operation as well as any
		preceding feeder appointments. If the
		lot has a load appointment active,
		cancel appointments after the following
		unload appointment. If the lot has an
		unload appointment active, cancel
		appointments after the current time. If
		the next operation is not a control
		operation or there are no more
		operations, schedule a move
		appointment after the unload
		appointment. Reschedule for the next
		process operation. If no appointments
		are active, cancel all future
		appointments and reschedule current
		process operation.
Process Operation	Factory State	The LSA will remove all non-active
Changed	Change	appointments. The LSA will then check
	(MES)	to see if the new process operation is a
		control or feeder process operation. If
		the process operation is a feeder, then
		the agent will schedule the next process
		operation. If the process operation is a
		control and the agent doesn't have an
		appointment for this process operation,
		it will schedule this process operation.
		If the lot has a processing appointment
		active, cancel appointments after either
		current appointment or following unload
		appointment (if present). If the
		appointment is in "near complete"
		status and the next process operation is
		not a control operation or there is no
		next operation in the process, schedule a
		move appointment after the current lot
		processing appointment. If the
		appointment is near complete and the
		next operation is a control operation,
		attempt to schedule the next process
		operation. If the lot has a move
		appointment active and the move is to a
		machine port destination, cancel
		appointments after the following load
		and unload appointments (if present)
		and following lot processing
		appointment. Otherwise, cancel all
		appointments after the move
		appointment and reschedule the current
		process operation. If the lot has a
		feeder appointment active, cancel all
		appointments after the feeder
		appointment and reschedule the next
		process operation as well as preceding
		feeder appointments. If the lot has a
		load appointment active, cancel
		appointments after the following unload
		appointment. If the lot has an unload
		appointment active, cancel
		appointments after the current time. If
		the next operation is not a control
		operation or there are no more
		operations, schedule a move
		appointment after the unload
		appointment. Reschedule for the next
		process operation. If no appointments
		are active, cancel all future
		appointments and reschedule current
		process operation.
Wafer Count	Factory State	If the wafer count for a lot decreases,
Decreased	Change	the MSA shrinks lot appointments on its
	(MES)	calendar that have not yet started. The
		MSA will try to shrink the appointment
		by the proper amount. The MSA
		cancels any unstarted lot appoitment
		that cannot be shrunk. The LSA
		subsequently reacts to the appointment
		changes made by the MSA, depending
		on the what the changes are.
Wafer Count	Factory State	If the wafer count for a lot increases,
Increased	Change	the MSA expands lot appointments on
	(MES)	its calendar that have not yet started.
		The MSA will try to expand the
		appointment by the proper amount. The
		MSA cancels any unstarted lot
		appoitment that cannot be expanded.
		The LSA subsequently reacts to the
		appointment changes made by the
		MSA, depending on the what the
		changes are.
Lot Terminated	Factory State	The system will cancel all appointments
	Change	for the lot.
	(MES)
Lot Moved In	Factory State	If the lot moves in to a feeder operation
	Change	that is not the first feeder operation of
	(MES)	the segment, the LSA will adjust the
		appointment's end time to equal the
		current time plus the process time for
		that operation. It will then set an end
		time alarm. If the feeder operation is
		the last feeder, the LSA will replace the
		max move appointment with an
		appropriate move appointment and
		updates the remaining transport time.
Lot Moved Out	Factory State	If the operation that the lot changed
	Change	from is a feeder operation, the LSA will
		completely shrink the feeder
		appointment and cancel subsequent
		feeder and maxMove appointments, and
		schedule the next operation and any
		preceding feeder appointments. If the
		operation that the lot changed from is a
		control operation, no action is taken
		(next operation would have been
		scheduled at near completion). If the
		operation the lot changed from is a
		normal (not control or feeder) operation,
		the LSA will schedule the operation to
		which the lot changed.
Experimental	Factory State	An ERF includes special instructions on
Request Form	Change	how to process a particular lot. An ERF
("ERF") Status	(MES)	may be attached to or removed from a
Change		lot, and the LSA is notified when this
		happens. The LSA will notify each lot
		processing appointment's MSA and
		subsequently react to appointment state
		changes (if lot no longer compatible
		with any future batch appointments in
		which it may be participating).
Override Lot	Factory State	A bid request and an appointment
Appointment	Change	change listener are created and returned
		to the MSA. (This is in response to an
		unscheduled lot being placed on a
		machine port.)
Machine	Appointment	LSA will determine if it can improve its
Advertises a	State Change	processing appointment for the
Time Slot		operation at the new time slot. If so,
		then the LSA cancel the appointment
		and publishes a submit bid message in
		attempt to reschedule the appointment
		for the advertised time slot.

TABLE 4

Reactive Scheduling Activities for PM Scheduling Agents

Event	Event Type	Reactive Scheduling Activities
PM/Qual	Appointment	The PM appointment is canceled and
Appointment	State Change	rescheduled.
Cancelled
Expand PM/	Appointment	The MSA initiates this change when the PM
Qual	State Change	appointment is running long. The PMSA will
Appointment		react to this change by shifting all
		appointments to the right of the PM
		processing appointment being expanded. The
		appointments that cannot be shifted are
		canceled and rescheduled. It will then
		expand the PM appointment to the specified
		time.
Make PM/	Appointment	The MSA initiates this change when the
Qual	State Change	processing of the PM has been interrupted.
Appointment		The MSA will change the status of the
Aborted		appointment to aborted. The PMSA will
		reschedule the appointment.
Make PM/	Appointment	The MSA initiates this change when the
Qual	State Change	MSA learns the PM has started. The MSA
Appointment		will change appointment to a processing
Processing		status.
Make PM/	Appointment	The MSA initiates this change when the PM
Qual	State Change	has completed processing and may shrink the
Appointment		appointment if appropriate. The PMSA will
Completed		notify the processing agent, change the status
		to completed, and update the last occurrence
		of the PM with the current wafer count on
		the machine or current time.
Make PM	Appointment	The MSA initiates this change when it is
Appointment	State Change	time for the following Qual to start. The
Active PM/		PMSA will change the status of the
Qual		appointment to "active".
Make PM	Appointment	The MSA initiates this change when it
Appointment	State Change	receives a Factory State Change indicating
Processing		the Qual portion of the PM appointment has
PM/Qual		started. The PMSA will change the status of
		the appointment to processing PM/Qual.
Shift PM/	Appointment	The PMSA will try to move the PM
Qual	State Change	appointment to the left. If it is unable to shift
Appointment		left, the system will cancel the appointment
Left		and reschedule it.
Shift PM/	Appointment	The PMSA will try to move the PM
Qual	State Change	appointment to the right. If it is unable to
Appointment		shift right, the system will cancel the
Right		appointment and reschedule it.
Shrink PM/	Appointment	The PMSA will shrink the PM appointment
Qual	State Change	to the specified time.
Appointment
Update	Appointment	The PM appointment commitment window is
Commitment	State Change	updated. The commitment window
Window For		represents the PMs earliest start time and
PM/Qual		latest delivery time for a given appointment.
Appointment
Override	Appointment	The PM appointment is cancelled
PM/Qual	State Change	within the calendar if it exist. It will
Appointment		then create a bid request and appointment
		change listener and return it to the MSA.
		This is in response to an unscheduled PM
		being started.
MES	Factory State	The PMSA will appropriately update the
Machine	Change	number of occurrences of the event within
Event		any PM or Qual that depends on this event.
Detected		It will then schedule any PMs or Quals
		triggered by the event occurrence what are
		not currently scheduled on its calendar.
Lot	Factory State	The PMSA will reevaluate the commitment
Processing	Change	windows for all PMs or Quals that are
Completed		scheduled based on a count of material
on Machine		processed. If the commitment window is
		invalid, the PMSA will either update the
		commitment window if the PM or Qual is
		scheduled within the new window, or it will
		cancel the existing appointment and
		reschedule within the new window. It will
		also schedule any PMs or Quals based on a
		count of material processed that have
		reached their trigger point and have not
		been schedule previously.
Alarm Fired	Alarm Event	The PMSA will schedule any time-based PM
		or Qual that has reached its trigger point and
		was not previously scheduled.

TABLE 5

Reactive Scheduling Activities for Resource Scheduling Agents

Event	Event Type	Reactive Scheduling Activities
Appointment Start	Alarm Event	This alarm indicates that the
Time Alarm Fired		scheduled start time of the specified
for Load (Unload)		load (unload) appointment has
Appointment		arrived. The resource appointment
		scheduler will make the appointment
		active if it is not active. It will
		also create an appointment end time
		alarm if needed. The resource
		appointment scheduler will inform
		the processing agent to start
		processing the appointment.
Appointment Start	Alarm Event	This alarm indicates that the
Time Alarm Fired		scheduled start time of the specified
for Discharge		discharge appointment has arrived.
Appointment		The resource appointment scheduler
		will make the appointment active if it
		is not active. It will also create an
		appointment end time alarm if
		needed. The resource appointment
		scheduler will inform the processing
		agent to start processing the
		appointment.
Appointment End	Alarm Event	This alarm indicates that the
Time Alarm Fired		scheduled end time of the specified
for Load (Unload)		load (unload) appointment has
Appointment		arrived. The resource appointment
		scheduler will expand the
		appointment with a percentage (e.g.,
		25%) of the originally scheduled
		duration until a maximum expansion
		percentage has been reached (e.g.,
		175%). Before expanding the
		appointment, the subsequent booked
		appointments may be shifted later in
		time. A new end time alarm is then
		set for the expanded load (unload)
		appointment.
Appointment End	Alarm Event	This alarm indicates that the
Time Alarm Fired		scheduled end time of the specified</