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SEMI E32-0997 © SEMI 1994 , 1997 40 15. The secon d atomic transfer n ow proceeds in a simil ar fash io n th rough steps 4–12 above. That done, sin ce t here are no f urther moves requ ired, the restore stag e begins, in…

SEMI E32-0997 © SEMI 1994, 199739

6. The AGV (as primary transfer partner) begins the

transfer.

7. The AGV performs the transfer. Notice that no

HOCommand messages are needed since this is a

passive transfer.

8. The AGV sends an HOVerify message to the

equipment via the host.

9. The equipment ensures that the cassette is no

longer sensed in its port and then sends an

HOVerify Response message (via the host) to the

AGV, followed by an “Atomic Transfer Complete”

event to the host.

10. Upon receipt of the HOVerify Response message,

the AGV sends an “Atomic Transfer Complete”

event to the host.

11. Each partner completes its RESTORE operations

and then sends a Transfer Job Complete message to

the host.

The transfer is now complete. The host may now direct

the AGV to deliver the cassette to a new destination.

A1-4.2 Active Transfer/Exchange of Cassettes — This

example addresses the situation where the factory

control system needs to remove a processed lot from an

equipment and immediately replace it with an

unprocessed lot. The assumptions are that the

processing of the lot on the equipment is nearing

completion and that the AGV has already acquired the

unprocessed lot that will next be placed on the

equipment. Direct micro level communications exist

between the AGV and the equipment. This will be an

interactive transfer.

The setup operations for the equipment are opening the

port door, driving the cassette indexer to the home

position, and checking for the presence of the proper

cassette. AGV setup is movement to the transfer

location for that equipment. During the transfer, the

equipment acts as the primary transfer partner, and will

unclamp/clamp the cassette (clamps hold the cassette in

the proper position). The AGV will interact with the

equipment as the secondary transfer partner.

The transfer proceeds as follows:

1. The host sends Transfer Job Create requests to the

equipment and to the AGV. The timing is chosen

so that the time required for the AGV to travel to

the equipment is approximately equal to the time

left to complete processing of the lot to be

transferred. The Transfer Job Create message to

each contains two atomic transfers, the first dealing

with the removal of the processed cassette from the

equipment and the second dealing with the loading

of the unprocessed cassette onto the equipment.

2. The AGV accepts the transfer job and begins the

first atomic transfer immediately, sending a

Transfer Job Started message to the host. Setup

begins — the AGV begins traveling toward its

transfer partner. The equipment accepts the transfer

job and retains it for later execution.

3. When processing completes on the lot, the

equipment begins the transfer job. It sends a

Transfer Job Started message to the host and

begins its setup operations for the first atomic

transfer.

4. The AGV completes its setup activity and sends a

“Committed To Transfer” event to the host. It also

sends a HOReady message to the equipment.

5. The equipment completes its setup, then sends a

“Committed to Transfer” event to the host and an

HOReady message to the AGV.

6. Since the AGV had previously declared itself

ready, the equipment sends an Atomic Transfer

Started event to the host and starts the transfer.

7. The equipment begins by sending an HOCommand

that results in the AGV reaching out and grasping

the cassette.

8. Upon receiving the Command Complete message

from the AGV, the equipment unclamps the

cassette, allowing its removal.

9. The equipment sends an HOCommand that results

in the AGV removing the cassette from the

equipment. The material sent and material received

events are sent to the host by the respective

partners.

10. When the equipment receives the Command

Complete message from the AGV, it considers the

transfer to be complete. It sends the HOVerify

message to the AGV.

11. The AGV sends the HOVerify Response message

to the equipment.

12. Each of the transfer partners now determines that

another atomic transfer is required in order to

complete the transfer job.

13. Each transfer partner now transitions to the second

atomic transfer. They each send “Atomic Transfer

Complete” events.

14. Each transfer partner now begins the new setup

phase. The AGV determines that it has already

reached the transfer point and has the unprocessed

cassette to be transferred. The equipment

determines that the port is now empty, and that the

door is open. This setup time was saved.

SEMI E32-0997 © SEMI 1994, 1997 40

15. The second atomic transfer now proceeds in a

similar fashion through steps 4–12 above. That

done, since there are no further moves required, the

restore stage begins, including “Atomic Transfer

Complete” events to the host.

16. Once restore operations are complete, each sends a

Transfer Job Complete message to the host. The

transfer is now complete.

A1-4.3 Sequential Moves — In this example, the

factory control system desires to move a cassette from

equipment “A” to equipment “B” using a fixed robot

stationed within reach of the two. Each piece of

equipment has a static port and will act as passive

transfer partners in all cases. The robot will act as the

primary partner for all transfers. The host system must

do the high-level planning of this move, determining

that the lot to be transferred will be ready to go, that the

robot is available, and that the receiving equipment is

available to receive the cassette.

To accomplish the transfer, two atomic moves are

required. First, the robot picks up the cassette at “A.”

Second, the robot deposits the cassette on “B.” The

gripper on the robot is considered its port in this case,

since that is the point at which ownership of the cassette

changes.

Since the step–by–step transfer details are similar to the

first two examples, they will be omitted. However, a

higher-level sequence will be given.

1. The host will send Transfer Job Create messages to

“A,” “B,” and the robot. The robot will be given

two sequential atomic moves to perform, the

equipment one each. Note that the Transfer Job

Create request to “B” could be delayed, if desired,

until the completion of the first atomic move.

2. The first atomic transfer is performed: the robot

removes the cassette from “A.” Note that no

HOCommands are issued, since the secondary

partner is passive.

3. The second atomic transfer is performed: the robot

places the cassette on “B.”

4. Both “A,” “B,” and the robot deliver Transfer Job

Complete messages to the host.

The transfer is complete.

An intelligent robot control system could combine the

two atomic moves discussed above into a single robot

program, achieving a more efficient transfer (e.g., no

redundant movement during the transfer). In such a

case, both “A” and “B” would need to be ready for

transfer before the robot program was executed. The

only limitation is that this combination would have to

match the model and messaging discussed above.

A1-4.4 Linked Lithography — The final example is

one where the micro level of material movement might

be used without the macro level messaging described in

this document. The linked lithography system described

below is not patterned after any existing system and

may not be the optimal implementation for such a

system.

For this example, the challenge is to transfer wafers

from a typical track system (following the coat/bake

process) into a stepper for imaging, and then back to the

track system for the develop process. In this example,

the stepper acts as a slave to the track system, accepting

wafers as they are given. The non–transfer-related

communications will not be discussed.

In the wafer transfer process, the track takes on the

macro level duties of the host. It is responsible for

informing the stepper that a wafer is to be transferred,

which wafer, and by what path and mechanism. It will

initiate the transfer in a method analogous to the

Transfer Job Create request. There is no transfer agent

in this case. Either equipment might act as the primary

transfer partner — it is irrelevant to this example.

The stepper and track will then exchange the normal

micro communications. First, the HOReady messages

will be sent. Next, the track will issue HOCommands to

cause the wafer to be physically transferred. Finally, the

HOVerify message transaction would occur.

Meaningful events would be reported to the host as

appropriate.

An alternative would be to design the system such that

the track system tells the stepper system, in effect, “I'll

be sending a series of wafers to you.” Since the

HOReady message contains sufficient information to

describe the transfer (assuming a specific transfer

recipe is not required), no specifics about the individual

transfers need be exchanged until the HOReady is sent.

In such a scheme, the stepper would take the HOReady

message as description of the specific transfer and

respond with an HOReady to match.

A1-4.5 Non–Compliant Transfer Partner — There will

be situations where only one of the transfer partners is

compliant with this standard. It is reasonable to use this

transfer methodology in some such cases, especially

those involving passive transfer. The host would be

responsible for emulating a compliant transfer partner

on behalf of the non–compliant partner (for the benefit

of the compliant partner). Examples of non–compliant

transfer partners might include a WIP rack, a human

transfer agent, an older process equipment, or any

material handling systems that support other protocols.

NOTICE: These standards do not purport to address

safety issues, if any, associated with their use. It is the

responsibility of the user of these standards to establish

appropriate safety and health practices and determine

the applicability of regulatory limitations prior to use.

SEMI makes no warranties or representations as to the

suitability of the standards set forth herein for any

particular application. The determination of the

suitability of the standard is solely the responsibility of

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other relevant literature respecting any materials

mentioned herein. These standards are subject to

change without notice.

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compliance with this standard may require use of

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takes no position respecting the validity of any patent

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item mentioned in this standard. Users of this standard

are expressly advised that determination of any such

patent rights or copyrights, and the risk of infringement

of such rights, are entirely their own responsibility.

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