U.S. patent application number 11/521575 was filed with the patent office on 2007-03-15 for methods and apparatus for a transport lift assembly.
This patent application is currently assigned to APPLIED MATERIALS, INC.. Invention is credited to Eric Andrew Englhardt, Jeffrey C. Hudgens, Sushant S. Koshti, Robert B. Lowrance, Michael R. Rice, Vinay Shah.
Application Number | 20070059153 11/521575 |
Document ID | / |
Family ID | 37865553 |
Filed Date | 2007-03-15 |
United States Patent
Application |
20070059153 |
Kind Code |
A1 |
Lowrance; Robert B. ; et
al. |
March 15, 2007 |
Methods and apparatus for a transport lift assembly
Abstract
Systems, methods and apparatus are provided for a transport lift
assembly that includes a chassis, at least one set of wheels
mounted on the chassis, a lift assembly mounted on the chassis, a
controller adapted to control the lift assembly, and a motor magnet
array mounted on the chassis. The transport lift assembly is
adapted to be driven in response to application of an external
magnetic field and to load and unload substrate carriers from
moving conveyors.
Inventors: |
Lowrance; Robert B.;
(Livermore, CA) ; Englhardt; Eric Andrew; (Palo
Alto, CA) ; Rice; Michael R.; (Pleasanton, CA)
; Shah; Vinay; (San Mateo, CA) ; Koshti; Sushant
S.; (Sunnyvale, CA) ; Hudgens; Jeffrey C.;
(San Francisco, CA) |
Correspondence
Address: |
DUGAN & DUGAN, PC
55 SOUTH BROADWAY
TARRYTOWN
NY
10591
US
|
Assignee: |
APPLIED MATERIALS, INC.
|
Family ID: |
37865553 |
Appl. No.: |
11/521575 |
Filed: |
September 13, 2006 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60717150 |
Sep 14, 2005 |
|
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|
60717335 |
Sep 14, 2005 |
|
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|
60717336 |
Sep 14, 2005 |
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Current U.S.
Class: |
414/809 |
Current CPC
Class: |
H01L 21/67715 20130101;
B65G 47/28 20130101; H01L 21/67706 20130101; B65G 29/00 20130101;
B65G 2203/025 20130101; B65G 47/52 20130101; Y10S 414/135 20130101;
Y10S 414/14 20130101 |
Class at
Publication: |
414/809 |
International
Class: |
B65F 9/00 20060101
B65F009/00 |
Claims
1. An apparatus comprising: a chassis; at least one set of wheels
mounted on the chassis; a lift assembly mounted on the chassis; a
controller adapted to control the lift assembly; and a motor magnet
array mounted on the chassis and adapted to drive the apparatus in
response to application of an external magnetic field.
2. The apparatus of claim 1 wherein the chassis includes at least
one bumper.
3. The apparatus of claim 1 wherein the at least one set of wheels
is adapted to cause the apparatus to roll in a circular path.
4. The apparatus of claim 3 wherein the circular path has a
diameter substantially equal to a diameter of a transfer station
track.
5. The apparatus of claim 1 wherein the lift assembly includes an
end effector with kinematic features adapted to support a substrate
carrier.
6. The apparatus of claim 1 wherein the controller further includes
a communication system adapted to receive commands directed to the
apparatus from a transfer station controller.
7. The apparatus of claim 1, further comprising a sensor for
determining a position of the apparatus on a transfer station
track.
8. A method comprising: traveling along a transfer station track;
receiving transfer station track position information from a
sensor; communicating track position and availability status to a
transfer station controller; receiving a load/unload instruction;
and executing the load/unload instruction.
9. The method of claim 8, further comprising transporting a
carrier.
10. The method of claim 8 wherein traveling along a transfer
station track includes rolling on a set of wheels adapted to roll
in a circular path having a diameter substantially equal to a
diameter of the transfer station track.
11. The method of claim 8 wherein communicating track position
includes determining track position based on the received transfer
station track position information and sending a wireless signal to
the transfer station controller indicating track position and
identifying information.
12. The method of claim 8 wherein communicating availability status
includes sending a wireless signal to the transfer station
controller indicating whether a carrier is present and identifying
information.
13. The method of claim 8 wherein executing the load/unload
instruction includes raising an end effector to contact a carrier
and disengaging the carrier from a cradle on a moving conveyor.
14. The method of claim 8 wherein executing the load/unload
instruction includes raising a carrier on an end effector and
engaging the carrier on a cradle on a moving conveyor.
15. A system comprising: a transport lift assembly adapted to be
individually controlled and including: a chassis, at least one set
of wheels mounted on the chassis, a lift assembly mounted on the
chassis, an onboard controller adapted to control the lift
assembly, and a motor magnet array mounted on the chassis and
adapted to drive the transport lift assembly in response to
application of an external magnetic field; a track including a
plurality of armature windings disposed along the track and adapted
to apply an external magnetic field to the transport lift assembly
when the transport lift assembly is on the track; and a control
system adapted to control the armature windings.
16. The system of claim 15 wherein the transport lift assembly
further includes a sensor for determining a position of the
transport lift assembly on the track.
17. The system of claim 15 wherein the chassis includes at least
one bumper.
18. The system of claim 15 wherein the at least one set of wheels
is adapted to cause the transport lift assembly to roll in a
circular path.
19. The system of claim 18 wherein the circular path has a diameter
substantially equal to a diameter of the track.
20. The system of claim 18 wherein an additional set of wheels is
horizontally oriented to roll along a wall surrounding the
track.
21. The system of claim 15 wherein the track includes an enclosure
adapted to contain particles.
22. The system of claim 21 wherein the enclosure includes a
negative air pressure.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] The present application claims priority to U.S. Provisional
Patent Application Ser. No. 60/717,150, filed Sep. 14, 2005 and
titled "METHODS AND APPARATUS FOR A TRANSPORT LIFT ASSEMBLY"
(Attorney Docket No. 9613/L2/SYNX/SYNX/JW), which is hereby
incorporated by reference herein in its entirety.
[0002] The present application also claims priority to U.S.
Provisional Patent Application Ser. No. 60/717,335, filed Sep. 14,
2005 and titled "METHODS AND APPARATUS FOR A TRANSFER STATION"
(Attorney Docket No. 9613/L/SYNX/SYNX/JW), which is hereby
incorporated by reference herein in its entirety.
[0003] The present application also claims priority to U.S.
Provisional Patent Application Ser. No. 60/717,336, filed Sep. 14,
2005 and titled "METHODS AND APPARATUS FOR A BAND TO BAND TRANSFER
MODULE" (Attorney Docket No. 9613/L3/SYNX/SYNX/JW), which is hereby
incorporated by reference herein in its entirety.
[0004] The present application is also related to the following
commonly-assigned, co-pending U.S. patent applications, each of
which is hereby incorporated herein by reference in its entirety
for all purposes:
[0005] U.S. patent application Ser. No. 10/650,310, filed Aug. 28,
2003 and titled "System For Transporting Substrate Carriers"
(Attorney Docket No. 6900);
[0006] U.S. patent application Ser. No. 10/764,982, filed Jan. 26,
2004 and titled "Methods and Apparatus for Transporting Substrate
Carriers" (Attorney Docket No. 7163);
[0007] U.S. patent application Ser. No. 10/650,480, filed Aug. 28,
2003 and titled "Substrate Carrier Handler That Unloads Substrate
Carriers Directly From a Moving Conveyor" (Attorney Docket No.
7676);
[0008] U.S. patent application Ser. No. 10/764,820, filed Jan. 26,
2004, and titled "Overhead Transfer Flange and Support for
Suspending Substrate Carrier" (Attorney Docket No. 8092); and
[0009] U.S. patent application Ser. No. 10/987,955, filed Nov. 12,
2004, and titled "Break-Away Positioning Conveyor Mount For
Accommodating Conveyor Belt Bends" (Attorney Docket No. 8611).
FIELD OF THE INVENTION
[0010] The present invention relates generally to electronic device
manufacturing, and more specifically to transporting substrates
within an electronic device manufacturing facility.
BACKGROUND OF THE INVENTION
[0011] Manufacturing of electronic devices typically involves
performing a sequence of procedures with respect to a substrate
such as a silicon substrate, a glass plate, etc. (Such substrates
may also be referred to as wafers, whether patterned or
unpatterned.) These steps may include polishing, deposition,
etching, photolithography, heat treatment, and so forth. Usually a
number of different processing steps may be performed in a single
processing system or "tool" which includes a plurality of
processing chambers. However, it is generally the case that other
processes are required to be performed at other processing
locations within a fabrication facility, and it is accordingly
necessary that substrates be transported within the fabrication
facility from one processing tool to another. Depending upon the
type of electronic device to be manufactured, there may be a
relatively large number of processing steps required to be
performed at a considerable number of different processing
tools/locations within the fabrication facility.
[0012] It is conventional to transport substrates from one
processing location to another via substrate carriers such as
sealed pods, cassettes, containers, open trays, cassettes and so
forth. It is also conventional to employ automated substrate
carrier transport devices, such as automatic guided vehicles,
overhead transport systems, substrate carrier handling robots,
etc., to move substrate carriers from tool to tool within the
fabrication facility or to transfer substrate carriers from or to a
substrate carrier transport device.
[0013] For an individual substrate, the total device fabrication
process, from formation of the substrate to cutting of individual
electronic devices from the finished substrate, may require an
elapsed time that is measured in weeks or months. Accordingly it
would be desirable to reduce substrate transfer time in an effort
to reduce non-value added time.
SUMMARY OF THE INVENTION
[0014] In a first aspect of the invention, an apparatus is provided
that includes a chassis, at least one set of wheels mounted on the
chassis, a lift assembly mounted on the chassis, a controller
adapted to control the lift assembly, and a motor magnet array
mounted on the chassis and adapted to drive the apparatus in
response to application of an external magnetic field.
[0015] In a second aspect of the invention, a method is provided
that includes moving a transport lift assembly along a transfer
station track, receiving transfer station track position
information from a sensor, communicating track position and
availability status to a transfer station controller, receiving a
load/unload instruction, and executing the load/unload
instruction.
[0016] In a third aspect of the invention, a system is provided
that includes a transport lift assembly adapted to be individually
controlled, a track including a plurality of armature windings
disposed along the track and adapted to apply an external magnetic
field to the transport lift assembly when the transport lift
assembly is on the track, and a control system adapted to control
the armature windings. The transport lift assembly includes a
chassis, at least one set of wheels mounted on the chassis, a lift
assembly mounted on the chassis, an onboard controller adapted to
control the lift assembly, and a motor magnet array mounted on the
chassis and adapted to drive the transport lift assembly in
response to application of an external magnetic field.
[0017] Numerous other aspects are provided, as are apparatus,
systems and computer program products in accordance with these and
other aspects of the invention. Each computer program product
described herein may be carried by a medium readable by a computer
(e.g., a carrier wave signal, a floppy disc, a compact disc, a DVD,
a hard drive, a random access memory, etc.).
[0018] Other features and aspects of the present invention will
become more fully apparent from the following detailed description,
the appended claims and the accompanying drawings.
BRIEF DESCRIPTION OF THE FIGURES
[0019] FIG. 1 is a schematic representation of a electronic device
manufacturing facility employing transfer stations according to
embodiments of the present invention.
[0020] FIG. 2 is a perspective drawing of a transfer station and
conveyors according to embodiments of the present invention.
[0021] FIG. 3 is a perspective drawing of the transfer station of
FIG. 2.
[0022] FIG. 4 is a cross-sectional perspective drawing of the
transfer station of FIG. 2.
[0023] FIG. 5 is a block diagram of components of a transfer
station according to embodiments of the present invention.
[0024] FIG. 6 is a perspective drawing of a front view of a
transport lift assembly according to embodiments of the present
invention.
[0025] FIG. 7 is a perspective drawing of a rear view of a
transport lift assembly according to embodiments of the present
invention.
[0026] FIG. 8 is a block diagram of components of a transport lift
assembly according to embodiments of the present invention.
[0027] FIG. 9 is a flowchart depicting an example method according
to embodiments of the present invention.
[0028] FIG. 10A depicts position and velocity graphs illustrating a
carrier loading motion profile process according to embodiments of
the present invention.
[0029] FIG. 10B depicts a more detailed version of some of the
position and velocity graphs of FIG. 10A.
[0030] FIG. 10C depicts position and velocity graphs illustrating a
carrier unloading process according to embodiments of the present
invention.
[0031] FIG. 10D depicts a more detailed version of some of the
position and velocity graphs of FIG. 10C.
DETAILED DESCRIPTION
[0032] Aspects of the present invention provide methods and
apparatus for transferring carriers (e.g., substrate carriers)
between two or more conveyors (e.g., continuously moving high-speed
overhead transport systems (OHT systems)) within a electronic
device manufacturing facility (Fab). The invention includes a
transfer station with a plurality of independent transport lift
assemblies (TLAs) that are each adapted to align with a moving
carrier on a conveyor, disengage the carrier from the conveyor
(e.g., using a lift assembly), transport the carrier to a second
conveyor, and transfer (e.g., mount) the carrier to the second
conveyor. The inventive transfer station enables transfers between
conveyors without having to stop the conveyors or TLAs and also
enables continuous transfer of carriers as the carriers arrive at
the transfer station. In other words, as fast as the carriers
arrive on one conveyor, the transfer station of the present
invention can operate to move the arriving carriers to another
conveyor (e.g., with available or open carrier positions).
[0033] The transfer station may include a track that guides the
TLAs to align with the conveyors. In one or more embodiments, the
track may be a circular track that is disposed in close proximity
to each of the conveyors. In some embodiments, other shape tracks
may be used (e.g., elliptical). For example, a portion of each
conveyor may pass directly over a different portion of the track. A
drive system (e.g., a closed-path linear motor) may be provided to
propel the TLAs around the track. In addition, a control system may
be provided to receive information about arriving carriers and/or
cradles and control the drive system to adjust an individual TLA's
speed to align with an incoming carrier (e.g., in anticipation of
an unload operation) or incoming conveyor location such as a cradle
(e.g., in anticipation of a load operation). The control system may
also control the drive system to adjust an individual TLA's speed
as part of the actual unloading and loading process. In some
embodiments, the track and lower portion of the TLAs may be
surrounded by an enclosure within which a negative air pressure is
maintained to capture any potentially contaminating particles. The
enclosure may include one or more access doors that allow rapid
replacement of TLAs.
[0034] Each TLA may include, for example, wireless communication
facilities to receive control signals (e.g., using a protocol such
as Bluetooth.RTM., http://www.bluetooth.org/spec/) from the
transfer station control system that directs a TLA to remove a
carrier from a conveyor or mount a carrier on a conveyor. In
response to such instructions, an individual TLA controller on
board the TLAs may be preprogrammed to cause the TLAs to execute a
load or unload procedure as instructed by the transfer station
controller/control system.
[0035] The TLAs may include a lift assembly that includes an end
effector with kinematic features to coupled to, support, and/or
align with substrate carriers. In some embodiments, the TLA may
include both horizontal and vertical oriented sets of wheels upon
which the TLA travels around the track. In a circular track
embodiment, the vertical oriented set of wheels may be canted so
that on its own, the TLA follows a circular path that matches the
diameter of the track. This feature of the TLA may reduce friction
on the wheels and thus, reduce particle generation.
[0036] Turning to FIG. 1, a schematic representation of an
electronic device manufacturing facility (Fab) 100 employing
transfer stations 102A-E is depicted. The Fab 100 includes numerous
processing tools 104A, 104B (only two of which are representatively
labeled) that are served by conveyors 106A-D. The transfer stations
102A-E and/or conveyors 106A-D may be coupled to and controlled by
one or more transport system controllers (TSC) 108.
[0037] In operation, the transfer stations 102A-E, conveyors
106A-D, and TSC 108 may be part of a continuously moving high-speed
overhead transport system (OHT system) that is adapted to deliver
carriers (not pictured) containing one or more substrates to the
processing tools 104A, 104B (and/or other processing tools of the
Fab 100). Each of the conveyors 106A-D may be implemented as a
closed loop band that is especially well suited for transporting
small lot size carriers, such as substrate carriers that hold a
single substrate or substantially fewer than twenty-five substrates
(e.g., less than thirteen and in some embodiments, five or less
substrates). The particular example Fab 100 depicted in FIG. 1
includes an OHT system with four independent conveyors 106A-D, each
including several features that make the example OHT system
particularly suitable for using small lot size carriers including:
high-speed, low maintenance, constantly moving conveyors 106A-D; a
carrier loading/unloading function that does not require stopping
or slowing the conveyors 106A-D; conveyors 106A-D that are able to
physically support many carriers at one time; and flexible
conveyors 106A-D that may be readily customized to a desired
transport path. These features are described further below.
[0038] Previously incorporated U.S. patent application Ser. No.
10/650,310, filed Aug. 28, 2003 and titled "System For Transporting
Substrate Carriers" (Attorney Docket No. 6900), discloses a
substrate carrier transport system or similar delivery system that
includes a conveyor for substrate carriers that is intended to be
constantly in motion during operation of the Fab which it serves.
The constantly moving conveyor is intended to facilitate rapid
transportation of substrates within the Fab so as to reduce the
total "dwell" time of each substrate in the Fab.
[0039] To operate a Fab in this manner, methods and apparatus are
provided for unloading substrate carriers from the conveyor, and
for loading substrate carriers onto the conveyor, while the
conveyor is in motion. Previously incorporated U.S. patent
application Ser. No. 10/650,480, filed Aug. 28, 2003 and titled
"Substrate Carrier Handler That Unloads Substrate Carriers Directly
From a Moving Conveyor" (Attorney Docket No. 7676), discloses a
substrate carrier handler at a substrate loading station or "tool
station" (e.g., adjacent a processing tool or integrated with a
processing tool) that may perform such loading/unloading operations
with respect to a moving conveyor. For example, a substrate loading
station or tool station may include a horizontal guide or crane
that is moveable vertically, and an end effector that is moveable
horizontally along the horizontal guide. Other configurations for
moving the end effector vertically and/or horizontally are
provided.
[0040] To unload a substrate carrier from a moving conveyor that
transfers substrate carriers (a "substrate carrier conveyor") and
that passes by the substrate loading station, the end effector is
moved horizontally at a velocity that substantially matches the
velocity of the substrate carrier as it is being transported by the
substrate carrier conveyor (e.g., by substantially matching
substrate carrier speed in a horizontal direction). In addition,
the end effector may be maintained in a position adjacent the
substrate carrier as the substrate carrier is being transported.
The end effector thus may substantially match a position of the
substrate carrier while substantially matching a velocity of the
substrate carrier. Likewise, conveyor position and/or velocity may
be substantially matched.
[0041] While the end effector substantially matches the substrate
carrier's velocity (and/or position), the end effector is raised so
that the end effector contacts the substrate carrier and disengages
the substrate carrier from the substrate carrier conveyor. A
substrate carrier similarly may be loaded onto the moving substrate
carrier conveyor by substantially matching end effector and
conveyor velocities (and/or positions) during loading. In at least
one embodiment, such substrate carrier handoffs between the end
effector and substrate carrier conveyor are performed at a
substantially zero relative velocity and/or acceleration between
the end effector and the substrate carrier.
[0042] Previously incorporated U.S. patent application Ser. No.
10/764,982, filed Jan. 26, 2004 and titled "Methods and Apparatus
for Transporting Substrate Carriers" (Attorney Docket No. 7163),
describes a conveyor system that may be employed with the
above-described substrate carrier transport system and/or tool
station for transporting substrate carriers between one or more
processing tools of a electronic device manufacturing facility. The
conveyor system may include a ribbon (or "band") that forms a
closed loop within at least a portion of the electronic device
manufacturing facility and that transports substrate carriers
therein. In one or more embodiments, the ribbon or band may be
formed from stainless steel, polycarbonate, composite materials
(e.g., carbon graphite, fiberglass, etc.), steel or otherwise
reinforced polyurethane, epoxy laminates, plastic or polymer
materials that include stainless steel, fabric (e.g., carbon fiber,
fiberglass, Kevlar.RTM. available from Dupont Corporation,
polyethylene, steel mesh, etc.) or another stiffening material,
etc. By orienting the ribbon so that a thick portion of the ribbon
resides within a vertical plane and a thin portion of the ribbon
resides within a horizontal plane, the ribbon is flexible in the
horizontal plane and rigid in the vertical plane. Such a
configuration allows the conveyor to be constructed and implemented
inexpensively. For example, the ribbon requires little material to
construct, is easy to fabricate and, due to its vertical
rigidity/strength, can support the weight of numerous substrate
carriers without supplemental support structure (such as rollers or
other similar mechanisms used in conventional,
horizontally-oriented belt-type conveyor systems). Furthermore, the
conveyor system is highly customizable because the ribbon may be
bent, bowed or otherwise shaped into numerous configurations due to
its lateral flexibility.
[0043] As indicated above, the example Fab 100 of FIG. 1 includes
four conveyors 106A-D (e.g., ribbons or bands) that each form a
loop through different quadrants of the example Fab 100. The
conveyors 106A-D may comprise, for example, the ribbons described
in previously incorporated U.S. patent application Ser. No.
10/764,982. Also as indicated above, the conveyors 106A-D may
transport carriers (not shown) between processing tools 104A, 104B
and each of the conveyors 106A-D comprise straight portions and
curved portions to form non-intersecting closed loops. Any number
of processing tools 104A, 104B, conveyors 106A-D, and/or loop
configurations may be employed.
[0044] The transfer stations 102A-E allow carriers to be moved from
one conveyor to another. For example, transfer station 102A may be
used to move carriers from conveyor 106A to conveyor 106B. In some
embodiments, a conveyor 102E may be adapted to allow direct
transfer of carriers between more than two conveyors. For example,
transfer station 102E may be used to move carriers from conveyor
106A to conveyor 106B, 106C, and/or 106D, from conveyor 106B to
conveyor 106A, 106C and/or 106D, from conveyor 106C to conveyor
106A, 106B, and/or 106D, and from conveyor 106D to conveyor 106A,
106B, and/or 106C. Any number of conveyors may be served by a
transfer station, not just two or four as depicted in the example
of FIG. 1. Also, although not shown in FIG. 1, in additional or
alternative embodiments, a transfer station may be adapted to
transfer carriers from a conveyor directly to a processing tool or
storage facility via a substrate loading station.
[0045] Each processing tool may include a substrate carrier handler
at a substrate loading station or "tool station" (not pictured) of
the processing tool 104A for unloading a substrate carrier from or
for loading a substrate carrier onto a respective conveyor 106A-D
as the conveyor passes by the tool station (as described in
previously incorporated U.S. patent application Ser. No.
10/650,480). For example, an end effector (not shown) of a tool
station of the processing tool 104A may be moved horizontally at a
velocity that substantially matches a velocity of the substrate
carrier as it is being transported by the conveyor 106A, maintained
in a position adjacent the substrate carrier as the substrate
carrier is being transported and raised so that the end effector
contacts the substrate carrier and disengages the substrate carrier
from the conveyor 106A. The substrate carrier then may be delivered
to the processing tool 104A. A substrate carrier similarly may be
loaded onto the moving conveyor 106A by substantially matching end
effector and ribbon velocities (and/or positions) during
loading.
[0046] Each tool station may include one or more load ports or
similar locations where substrates or substrate carriers are placed
for transfer to and/or from a processing tool (e.g., one or more
docking stations, although transfer locations that do not employ
docking/undocking movement may be employed). Various substrate
carrier storage locations also may be provided at each tool station
for substrate carrier buffering at a processing tool.
[0047] The example OHT system depicted in FIG. 1 includes a
transport system controller (TSC) 108 for monitoring, controlling
and/or directing operation of the conveyors 106A-D, the tool
station at each processing tool 104A, 104B, and/or the transfer
stations 102A-E. Although not shown in FIG. 1, the TSC 108 may be
coupled to and/or in communication with each tool station at each
processing tool 104A, 104B, and/or each transfer station 102A-E.
For example the TSC 108 may control/monitor the speed and/or status
of the conveyors 106A-D, allocate cradles of the conveyors 106A-D
that are used to support/transport substrate carriers, monitor the
status of such cradles, provide such information to each tool
station and/or transfer station 102A-E, or the like. Likewise, each
tool station may include tool station software (TSS) for
controlling tool station operation (e.g., loading or unloading of
substrate carriers to/from the conveyors 106A-D, transporting of
substrate carriers to/from load ports or storage locations of the
tool station and/or processing tool serviced by the tool station,
etc.). A material control system (MCS) (not shown) may be coupled
to and/or in communication with the TSC 108, the transfer stations
102A-E, and/or the tool station software of each tool station of
each processing tool for affecting operation of the same. The TSC
108, the transfer stations 102A-E, each TSS and/or the MCS may
include a scheduler (not shown) for controlling scheduling of the
operations performed by the TSC 108, the transfer stations 102A-E,
the TSS and/or the MCS.
[0048] The topology of the Fab 100 depicted in FIG. 1 is designed
to make the Fab 100 more fault tolerant while at the same time,
enhance performance characteristics, particularly in terms of
substrate throughput. In some embodiments, a single conveyor may be
used throughout a Fab. However, if the conveyor fails or must be
stopped in a single conveyor Fab, all carrier transfers via the
conveyor are stopped. However, through the use of multiple
conveyors 106A-D and multiple transfer stations 102A-E, transport
of carriers may continue even if one or more of the conveyors
102A-D are stopped. For example, if a carrier needs to be
transported from processing tool 104A to processing tool 104B and
both conveyor 106B and transfer station 102E have been stopped for
repair, the carrier may still be transported between the processing
tools 104A, 104B via conveyor 106A, transfer station 102D, conveyor
106D, transfer station 102C, and conveyor 106C.
[0049] Turning to FIG. 2, a perspective drawing of an example
embodiment of a transfer station 102A and conveyors 106A, 106B
(only the bands 200 are shown) is depicted. Cradles 202 are coupled
to each of the bands 200 of the conveyors 106A, 106B and are
adapted to support substrate carriers 204. TLAs 206 which may each
include a lift assembly (described below) are also adapted to
support substrate carriers 204. In the embodiment depicted in FIG.
2, cradles 202 support the carriers 204 from above and TLAs 206
support carriers 204 from below. However, other alternative
configurations are possible including TLAs that support carriers
from above and/or cradles that support carriers from below.
[0050] A transfer station 102A may also include sensors 208 coupled
to the transfer station and/or the conveyors 106A, 106B. The
sensors 208 may include cameras, through-beam detectors, or other
devices suitable for detecting/determining the arrival and/or
velocity of a carrier 204 and/or an empty cradle 202. In addition,
sensors 208 may be used to determine/detect the position of a lift
assembly on a TLA (e.g., up or down), the speed and/or position of
a TLA, and/or the relative position, speed, and/or acceleration of
a TLA/carrier to a cradle/carrier and vice versa. Such information
may be provided to the TSC 108 (FIG. 1) and employed to
control/affect substrate carrier transfers.
[0051] As indicated above, the particular depiction of the
conveyors 106A, 106B in FIG. 2 omits the support, guide, and drive
apparatus that may be used in conjunction with the depicted bands
200. Support apparatus may be used to hold or support the bands 200
in a horizontal plane at a desired height above the transfer
station 102A. Guide apparatus may be used to direct the bands 200
in a path that substantially matches a portion of the track of the
transfer station 102A. Drive apparatus may be used to move the
bands 200 through the guide apparatus. In some embodiments, a
series of motor driven rollers mounted to a frame may be used to
support, guide, and drive the bands 200. The bands 200 are dispose
so that carriers 204 brought to the transfer station 102A via the
conveyors 106A, 106B may be unloaded from cradles 202 of the
conveyors 106A, 106B by TLAs 206 of the transfer station 102A.
Likewise, empty cradles 202 arriving at the transfer station 102A
on the bands 200 may be loaded with carriers 204 by the TLAs
206.
[0052] FIG. 2 depicts a transfer station 102A suitably sized to
accommodate two conveyors 106A, 106B. Depending on various factors
including the speeds of the bands, the spacing of cradles on the
bands, and the amount of time needed to remove/mount a carrier, the
size of a transfer station may be altered to accommodate transfers
from/to any number of bands. For two bands 200 as depicted in FIG.
2 that are moving at approximately the same speed, for example, the
diameter of a transfer station that accommodates carriers spaced
approximately 500 mm apart and arriving at a rate of approximately
180 carriers per minute, may be as small as approximately 2.5
meters. Transfer stations having smaller diameters are possible,
particularly with slower moving bands and/or with different
configurations. TLAs on the example transfer station described
above may circulate at approximately 12 revolutions per minute and
such a transfer station is capable of transferring 10,800 carriers
per hour from one band to another.
[0053] In operation, the TLAs 206 continuously circulate in the
transfer station 102A, independently unloading, transporting, and
loading carriers 204 as directed by the TSC 108 (FIG. 1). For
example, the TSC 108 may receive information from sensors 208 or
the transfer station 102A indicating the arrival of a carrier 204.
The TSC 108 may then direct the transfer station 102A to align an
available TLA 206 with the arriving carrier 204 by matching speed
with the carrier 204. The TLA 206 may receive instructions from the
TSC 108 and/or the transfer station 102A, and unload the carrier
204 from the band 200 and transport the carrier 204 to the other
side of the transfer station 102A. The TLA 206 then may load the
carrier 204 onto an arriving empty/available cradle 202 detected by
the sensor 208.
[0054] Turning to FIG. 3, a perspective drawing of the transfer
station 102A of FIG. 2 is shown without conveyors. A single carrier
204 is shown supported by a TLA 206 (obscured) under the carrier
204. The transfer station 102A includes a track 300 that is
surrounded by an enclosure 302. The track 300 is supported by a
frame 304. A drive system 306 may surround the perimeter of the
track 300 and a controller 308 may be coupled to the transfer
station 102A. The controller 308 may be a local controller.
[0055] In operation, the TLAs 206 transport carriers 204 around the
track 300. As will be described in detail below, the TLAs 206 can
also load and unload carriers 204 from an overhead transport (OHT)
system by raising and lowering a lift assembly while aligning with
a cradle 202 on a conveyor 106A (of FIG. 2). The TLAs 206 are each
driven by the drive mechanism 306, which, in some embodiments, may
include a closed-path linear motor. As shown in FIG. 3, the linear
motor may include an array of side-by-side armature windings or
motor coils that can each be individually energized to each create
a magnetic field to push or pull permanent magnets mounted on the
TLAs 206. The present invention may be implemented so that the
speed of the TLAs 206 may be independently controlled and adjusted
via control of the drive mechanism 306. The drive mechanism 306 may
be controlled by the TSC 108 (FIG. 1) directly or, alternatively,
by a local controller 308 and, in some embodiments, under the
direction of the TSC 108. Thus, the speed and position of each TLA
206 may be independently controlled via the drive mechanism 306 in
response to signals from the controller 308 and/or the TSC 108. The
controller 308 may control the speed and position of TLAs 206 in
response to information from the sensors 208 (of FIG. 2) and/or in
response to signals from the TLAs themselves. Further details
regarding the construction and operation of linear motors may be
found in U.S. Pat. No. 6,713,902 to Chitayat which is hereby
incorporated herein by reference for all purposes.
[0056] The enclosure 302 may include a series of panels on both
sides of the track 300 that define a volume within which the TLAs
206 travel. The enclosure 302 depicted in FIG. 3 includes an
opening or slot 310 at the top from which the lift assembly of each
TLA protrudes. In addition to supporting the track 300, the frame
304 may include an integral particle control system. For example,
the frame 304 may be constructed of hollow, tubular members that
are coupled to openings (not shown) in the bottom of the enclosure
302 and a vacuum source 312. Through the frame members, vacuum
pressure may be applied to the volume defined by the enclosure 302.
Any particles generated by the motion of the TLAs may thus be
removed from the transfer station 102A via the openings in the
bottom of the enclosure 302 and carried away via the frame 304. A
separate particle control system (not shown) may alternatively or
additionally be coupled directly to the enclosure 302 for removing
particles therefrom.
[0057] Turning to FIG. 4, a cross-sectional perspective drawing
showing more details of the transfer station 102A of FIG. 2 is
provided. As with FIG. 3, a single carrier 204 is shown supported
by a TLA 206 under the carrier 204. The transfer station 102A
includes the track 300 that is surrounded by the enclosure 302. The
track 300 is supported by the frame 304 and the drive system 306
surrounds the perimeter of the track 300. In addition to the track
300, the TLAs 206 may contact an upper roadway 400 and lower
roadway 402 that both run along the inner surface of the exterior
portion of the enclosure 302. One or more access port doors 404 may
be included in the interior portion of the enclosure 302. As shown
through the opening of the access port door 404, the TLA 206 may
include a set of two vertical wheels 406 and a set of four
horizontal wheels 408. In some embodiments, more or less vertical
and/or horizontal wheels may be included on a TLA. The transfer
station 102A may further include a power transfer system 410 that
also may run along the inner surface of the exterior portion of the
enclosure 302 proximate to the TLAs.
[0058] As indicated above, the enclosure 302 may be a particle
containment enclosure adapted to prevent potentially contaminating
particles generated by moving parts within the enclosure 302 from
being deposited or released into the atmosphere of the Fab 100. In
some embodiments, a negative air pressure (e.g., vacuum pressure)
may be maintained within the enclosure 302. In such embodiments,
the negative air pressure may be applied via the frame 304 of the
transfer station 102A and/or directly to the enclosure 302. The
frame 304 may be embodied as a series of interconnected hollow
members that provide a number of suction paths from the bottom of
the enclosure 302 by which a vacuum may draw away any particles
generated within the transfer station 102A. Thus, a down draft may
be created within the enclosure 302 from top to bottom such that
particles are pulled from the TLAs 206 and out of the transfer
station 102A via the frame 304. Such a particle containment system
may be used to adhere to a better than class 1000 cleanroom rating
(e.g., maintain a particle density less than one thousand particles
larger than 0.5 microns in each cubic foot of air space in
compliance with Federal Standard 209) which is desirable within a
Fab 100.
[0059] In operation, as the drive system 306 propels the TLAs 206
around the transfer station 102A, the vertical wheels 406 roll
along the track 300. The vertical wheels 406 may be canted or
otherwise adapted to cause the TLA 206 to naturally roll in a
circle that matches the shape of the track 300. Thus, lateral
rolling friction is minimized and particle generation is greatly
reduced. Note that a circular track 300 that has a constant radius
of curvature further allows the TLAs 206 with matched, canted
vertical wheels 406 to roll with minimum friction and particle
creation, thereby providing for a reduction in particulate
contaminants being introduced into the manufacturing environment.
In additional or alternative embodiments, the track 300 may be
angled or banked at a constant pitch to minimize friction and
particle generation.
[0060] To provide a balancing centripetal force, the horizontal
wheels 408 also roll on the upper roadway 400 and lower roadway 402
as the TLAs 206 are propelled around the transfer station 102A. The
track 300, the upper roadway 400, and the lower roadway 402 may
each include a thin polycarbonate top layer that helps resist
particle generation. Any other practicable material may
alternatively be used as a surface for the track 300 and/or
roadways 400, 402.
[0061] In some embodiments, the TLAs 206 may receive power to
operate on-board functions (e.g., the lift assembly, wireless
communications, sensors, etc.) from the transfer station 102A. The
power transfer system 410 may include a slip ring that provides an
electrical contact to each of the TLAs 206. Alternatively,
transformers may be used to transfer power to the TLAs 206 without
using a contact. In either embodiment, on-board batteries may be
installed in the TLAs 206 to store energy received from the power
transfer system 410.
[0062] As mentioned above, the enclosure 302 may include any number
of access port doors 404 which can be opened on hinges as shown in
FIG. 4 or completely removed so as to expose other components of
the transfer station 102A. The access port doors 404 may be opened
to perform any cleaning, maintenance, or repair operations. The
access port door opening may be sufficiently large to allow a TLA
206 to be easily removed from the track 300 and replaced with a
substitute TLA 206 within a matter of a seconds.
[0063] Turning to FIG. 5, various components of an example
embodiment of a transfer station 102A are depicted in a block
diagram. A controller 308 may be in wireless two-way communication
with a number of TLAs 206. The controller 308 may also be coupled
to a drive system 506, a particle control system 508, a power
transfer system 510, and a sensor system 512. The controller 308
may also include a communications port 514 to communicate with a
TSC and/or a MCS within the Fab.
[0064] The controller 308 may be implemented as any computer,
microprocessor, or computer system which may be adapted or
programmed to provide control over the operation of the transfer
station 102A. In some embodiments, the controller 308 may be a
network computer equipped with a communications port 514 for
facilitating communications with other computers and/or systems.
For example, the controller 308 can be controlled by, or provide
information regarding the operation of the transfer station 102A or
any system or component of the same, to an external computer or
control system, such as, for example, a manufacturing execution
system (MES) for a Fab.
[0065] The TLAs 206 (described in detail below) may communicate
wirelessly with the controller 308 using any practicable protocol
such as, for example, Bluetooth.RTM. or wireless Ethernet. In some
embodiments, the TLAs 206 may provide status information to the
controller 308, for example, indicating the completion of a
transfer, a need for service, a current track position, an error
condition, speed, "lift up," "lift down," "carrier centered," "low
battery," "battery full," "power transfer disabled," "power
transfer enabled", or the like. In some embodiments, the TLAs 206
may signal to the controller a need to accelerate or slow down to
match the speed of a cradle or to remove a carrier from a cradle,
for example. The controller 308 may, in response, control the drive
system 506 to energize or de-energize an appropriate motor coil to
achieve the desired effect on the TLA 206. In alternative or
additional embodiments, the controller 308 may signal instructions
to the TLAs 206 based on information received from the sensor
system 512 and/or from a TSC (e.g., via the communication port
515). For example, the controller 308 may assign a TLA 206 to
unload a carrier from a particular incoming cradle or to load a
carrier onto an arriving cradle.
[0066] In another example, the controller 308 may signal a TLA 206
to unload a carrier from a conveyor, hold it for a specific amount
of time (e.g., three revolutions around the transfer station 102A),
and then load the carrier back onto the same conveyor. In this
example, the transfer station 102A may serve to merely delay or
relocate a particular carrier on a conveyor, for example, to give a
downstream tool station more time to prepare for the arrival of the
particular carrier. This may allow the carrier's substrates to be
processed sooner instead of having to complete another full circuit
on the conveyor because the tool station would not have been ready
at the original arrival time.
[0067] In some embodiments, the particle control system 508, which
may include a vacuum pump or other vacuum supply, may be controlled
and/or monitored by the controller 308. For example, if a loss of
vacuum pressure within the enclosure 302 (FIG. 3) is detected by
the sensor system 512, the controller 308 may attempt to restart
the particle control system 508. Likewise, the power transfer
system 510 may, for example, be activated by the controller 308 in
response to a signal from the TLAs 206 that onboard battery power
is running low.
[0068] Turning to FIGS. 6 and 7, perspective drawings of a front
view (FIG. 6) and rear view (FIG. 7) of an example embodiment of a
transport lift assembly (TLA) 206 are provided. The TLA 206
includes a chassis 602 that supports a lift assembly 604 (shown in
a lowered position). The lift assembly 604 includes a lift platform
606 (also referred to herein as an end effector) mounted on a lift
slide 608 that is driven up and down by a linear lift actuator 610
within a lift tube 612. In addition to the lift assembly 604, a set
of two vertical wheels 614, a set of four horizontal wheels 616, a
power supply 618, a battery 620, a TLA controller 622, and front
and rear bumpers 624 are supported by or mounted to the chassis
602. Referring to FIG. 7, a linear motor magnet array 700 and power
pick-up contacts 702 are mounted on the rear side of the chassis
602. A position sensor 704 is mounted to the rear bottom edge of
the chassis 602 and coupled to the TLA controller 622 depicted in
FIG. 6.
[0069] With reference once again to both FIGS. 6 and 7, the chassis
602 may be constructed of any suitable material such as cast
aluminum. In an exemplary embodiment, the chassis may be a single
or integrated structure having the above-described components
integrated therewith and/or attached thereto. In another exemplary
embodiment, the chassis 602 may be formed of two or more
structures.
[0070] In operation, the lift platform 606, which may include
kinematic features 626, is adapted to engage mating kinematic
features in the bottom of a substrate carrier 204 (FIG. 2) and to
provide support when raising and lowering the carrier 204. When
either loading a carrier onto a conveyor or unloading a carrier
from a conveyor, the lift assembly 604 (and TLA 206) may follow a
predetermined/preprogrammed motion profile (described in detail
below with respect to FIGS. 11A-D) under the control of the TLA
controller 622 and/or the controller 308. When loading a carrier
onto a conveyor, the linear lift actuator 610 pushes the lift slide
608 up through the lift tube 612. This raises the lift platform 606
supporting the carrier to be loaded, up to the cradle so that a
flange on top of the carrier engages the cradle. Likewise, when
unloading a carrier from a conveyor, the linear lift actuator 610
pushes the lift slide 608 up through the lift tube 612 to raise the
lift platform 606 so as to engage the kinematic features 626 in the
mating recesses in the bottom of the carrier. The carrier is then
lifted off of the cradle attached to the conveyor and lowered clear
of the cradle.
[0071] As described above, a TLA 206 may include two sets of wheels
614, 616. The axels of the vertical wheels 614 may be angled
relative to each other so that the TLA 206 tends to roll in a
circular path. The angle of the axels relative to each other may be
set such that the circular path that the TLA follows, matches the
track 300 of the transfer station 102A. Alternatively or
additionally, the vertical wheels 614 may themselves be angled such
that the diameter of the wheel on one side is smaller than the
diameter of the same wheel on the other side. Such a wheel
naturally follows a circular path and the diameter of the circular
path is a function of the relative difference in the diameters of
the two sides of the wheel. The difference may be selected such
that the wheels follow a circular path that matches the track 300
of the transfer station 102A. As indicated above, by angling the
vertical wheels 614 and/or selecting angled wheels for use as the
vertical wheels 614 (e.g., wheels adapted to follow a circular path
that matches the track 300 of the transfer station 102A), rolling
friction is reduced and potentially contaminating particle
generation is minimized. Two vertical wheels 614 are depicted as
being used in the TLA embodiment of FIG. 6, however, one, three,
four, or more wheels 614 may be used in alternative embodiments.
The vertical wheels may be made from a polyurethane or polyethylene
material or any other practicable material. Polyurethane may be
selected, for example, because of its characteristics including
providing a quiet rolling surface.
[0072] Because each TLA 206 is operated independently of the other
TLAS, in some embodiments, the possibility exists that two or more
TLAs may contact each other while circulating within the transfer
station 102A. Bumpers 624 may be provided on either end of the TLA
206 to protect the vertical wheels 614 (and the TLA 206) from other
TLAs that may collide with the TLA 206 within the transfer station
102A. The bumpers 624 may be made from a shock absorbing material
such as a low derometer polyurethane or any other practicable
material.
[0073] The TLA 206 may also use horizontal wheels 616 to guide the
TLA 206 in the transfer station 102A and provide centripetal
support to the TLA 206 as it travels on the roadways 400, 402 of
the transfer station 102A. The horizontal wheels 616 also serve to
maintain the linear motor magnet array 700 and power pick-up
contacts 702 on the rear of the TLA 206 at a constant distance from
the drive system 306 and power transfer system 410, respectively.
Four horizontal wheels 616 are depicted as being used in the TLA
embodiment of FIG. 6, however, one, two, three, five, or more
wheels 616 may be used in alternative embodiments. The horizontal
wheels 616 may be made from a ultra high molecular weight (UHMW)
polyethylene material or any other practicable material. UHMW
polyethylene may be chosen, for example, because of its lubricity
and high abrasion resistance.
[0074] In embodiments where the TLA 206 receives energy via power
pick-up contacts 702, the contacts 702 are located on the TLA 206
so as to align with a slip ring in the transfer station 102A which
embodies the power transfer system 410. The contacts 702 are
coupled to the power supply 618 which is coupled to the battery
620, the TLA controller 622, and the linear lift actuator 610 via
the TLA controller 622. In addition to supplying power to the TLA
controller 622, the power supply 618 is operative to charge and
maintain the battery 620 when the power transfer system 410 is
enabled/supplying power and to draw power from the battery 620 when
the power transfer system 410 is disabled/not supplying power.
[0075] In alternative embodiments, the power transfer system 410
may include a transformer coupled power transfer mechanism. The TLA
206 may be equipped with a transformer (e.g., in place of the power
pick-up contacts 702) that generates electricity for the TLA 206 as
it is moved through magnetic fields created by energized
transformers disposed around the circumference of the transfer
station 102A.
[0076] The linear motor magnet array 700 mounted on the TLA 206
provides magnets that are acted upon by the drive system 306. The
array 700 may use very strong permanent magnets such as those made
from neodemium or neodemium-boron. The drive system 306, which may
include a closed-path linear motor, creates magnetic fields
adjacent the TLA's linear motor magnet array 700 by energizing
selected windings of the linear motor to push or pull the TLA's
linear motor magnet array 700, and consequently the TLA 206. In
this manner, the speed and position of the TLA 206 can be
accurately controlled via the drive system 306. The drive system
306 may be controlled in response to TLA position information that
is determined via the position sensor 704. The position sensor 704
may be a linear position sensor which allows accurate determination
of the TLA's position in the transfer station 102A. The position
sensor 704 may communicate with the drive system 306 directly or
may be coupled to the TLA controller 622 to facilitate providing
feedback to the transfer station controller 308/drive system 306
for positioning the TLA 206 below an arriving carrier to be
unloaded, for example. In some embodiments, the position sensor may
include several sensors disposed around the circumference of the
track 300 and the TLAs 206 may merely include a linear scale that
the position sensors detect to determine TLA position. Thus, the
position of the TLAs may be determined by either the transfer
station 102A or the TLAs themselves.
[0077] Turning now to FIG. 8, a block diagram illustrating
components of a transport lift assembly 206, and particularly the
TLA controller 622, is provided. The TLA controller 622 may include
a processor 800, associated memory 802 for storing executable code
804, communications facilities (e.g., a communications port 806),
and a sensor system 808 for monitoring various sensors 810, 704 for
controlling the TLA 206 and particularly the lift assembly 604. The
processor 800 may be any suitable microprocessor or CPU that may be
adapted for real time control of the TLA 206. The executable code
804 stored within the memory 802 may include sequences of lift
assembly control commands that implement motion profile processes
for loading and unloading carriers from conveyors. The
communication port 806 may include a transmitter and receiver
adapted to wirelessly exchange information with the transfer
station controller 308 or other systems using any practicable
protocol such as, for example, Bluetooth.RTM. or wireless Ethernet.
Sensors 810, 704 coupled to the sensor system 808 for controlling
the lift assembly 604 may include one or more sensors for detecting
the position (e.g., up or down) of the lift platform 606, one or
more sensors for detecting whether a carrier is currently on the
lift platform 606, one or more sensors for determining that the
lift platform 606 is centered below a carrier or cradle and ready
to unload or load a carrier, and the like.
[0078] The TLA controller 622 may also be connected to the lift
assembly 604 to actually signal the lift actuator 610 to execute
motion profile processes. The TLA controller 622 may also be
connected to the power system 812 to receive electrical power from
the battery 620 and/or the power supply 618.
[0079] Turning to FIG. 9, a flowchart depicting an example method
900 of transferring a carrier from one conveyor to a second
conveyor is provided. The method 900 commences at step 902. At step
904, the TLAs 206 are propelled along the transfer station track
300 by the drive system 506. In step 906, transfer station track
position information is received by each individual TLA 206 from a
respective onboard position sensor 704. In step 908, the TLAs'
identity, track position, and availability status are communicated
wirelessly to the transfer station controller 308. In step 910, a
transfer instruction for a particular target carrier is
communicated from the transfer station controller 308 to a
particular available TLA 206. In step 912, the TLA 206 is aligned
with the target carrier to be transferred that is arriving on the
first conveyor. Aligning the TLA 206 with the target carrier may
include sensing the position of the arriving carrier using sensor
208 and changing the speed of the TLA 206 to match the speed of the
arriving carrier. Changing the speed of the TLA 206 may be affected
by the transfer station controller 308 by signaling to the drive
system 506 in response to alignment information determined by and
received from the TLA 206.
[0080] In step 914, the target carrier is removed from the first
conveyor by the TLA 206. Removing the carrier may include raising
an end effector (e.g., the lift platform 606) of the TLA 206 once
the TLA 206 has been aligned with the carrier to be transferred.
The lift platform 606 may be raised to contact the carrier and
execute an unload motion profile process (described in detail below
with respect to FIGS. 10C-D) to disengage the carrier from the
moving conveyor.
[0081] In step 916, the carrier is transported to the second
conveyor. Transporting the carrier includes propelling the TLA 206
around the track 300 of the transfer station 102A via the drive
system 506 (e.g., using a linear drive motor 306). In some
embodiments, the TLA 206 bearing the carrier may simply circulate
on the track 300 until an available cradle arrives, or, in
additional or alternative embodiments, the TLA 206 may be
instructed to load the carrier back onto the first conveyor to
merely relocate the carrier on the first conveyor. This may be done
to delay a carrier's arrival at a tool station at another location
in the Fab until the tool station is ready for the carrier.
[0082] Returning to the method 900 of FIG. 9, in step 918, the TLA
is aligned with an arriving (available) target cradle on the second
conveyor. The target cradle may be a particular cradle previously
identified or it may simply be the next available cradle on the
second conveyor to arrive at the transfer station 102A when the TLA
206 is ready to unload. As above, aligning the TLA with the
arriving target cradle may include sensing the position of the
arriving cradle on the second conveyor and changing the speed of
the TLA to match the speed of the arriving cradle.
[0083] In step 920, the carrier is mounted onto the second
conveyor. Mounting or loading the carrier may include raising the
carrier to the target cradle on the second conveyor via the end
effector (e.g., the lift platform 606) of the TLA 206 once the TLA
206 has been aligned with the target cradle. A load motion profile
process (described in detail below with respect to FIGS. 10A-B) may
be executed to engage the carrier on the cradle on the moving
conveyor. The method 900 completes at step 922.
[0084] FIGS. 10A-D depict exemplary motion profile processes for
the lift assembly 604. In at least one embodiment of the invention,
when such motion profiles are employed, only the TLA's position
sensor 704 need be employed (e.g., the other sensors 208, 810 may
be eliminated). With reference to FIG. 10A, curve C1 illustrates
lift assembly 604 velocity along the x-axis (horizontal direction
in which the conveyor 106A travels) during a load operation. Curve
C2 illustrates lift assembly 604 velocity along the z-axis
(vertical direction) during a load operation. Curve C3 illustrates
lift assembly 604 z-axis position and curve C4 illustrates lift
assembly 604 x-axis position during a load operation. FIG. 10B is
similar to FIG. 10A, but shows the z-axis position data enlarged.
FIGS. 10C-D are similar to FIGS. 10A-B, but illustrate x-axis
velocity (curve C1'), z-axis velocity (curve C2'), z-axis position
(curve C3') and x-axis position (curve C4') for the lift assembly
604 during an unload operation. Note that FIGS. 10A-B show the
z-axis position data (curve C3) at a lower z-position during a
start of a substrate carrier load operation (e.g., to compensate
for the size of a substrate carrier).
[0085] With reference to FIGS. 10A-B and curves C1-C4, the lift
assembly 604 may perform similar raisings, lowerings, and
accelerations as described above with reference to a load
operation. For example, after receiving a signal to perform a load
operation, the lift assembly 604 (via the TLA 206) accelerates to
match the velocity of the conveyor 106A in the x-direction (curve
C1) between times T1 and T2. Thereafter, between times T3 and T4,
the lift assembly 604 (curve C3) is raised to the level of the
conveyor 106A; for example, such that a flange on the top of the
substrate carrier 204 to be loaded onto the conveyor 106A is above
the cradle 202 that is to receive the substrate carrier 204.
[0086] Between times T5 and T6, the lift assembly 604 is
accelerated (curve C1) above the speed of the conveyor 106A (and
then is decelerated back to the speed of the conveyor 106A) so that
the flange of the substrate carrier 204 is positioned above the
cradle 202. At time T7, with the flange of the substrate carrier
204 positioned above the cradle 202, the lift assembly 604 lowers
(curve C3) and stops as the flange contacts the cradle 202 (as
shown at time T8). The lift assembly 604 then lowers until time T9
and the substrate carrier 204 remains on the cradle 202. The
substrate carrier 204 thereby is transferred to the conveyor 106A
with substantially zero relative velocity and/or acceleration
(e.g., at time T8) between the lift assembly 604 and the cradle
202. For example, because the lift assembly 604 stops as the flange
engages the cradle 202, transfer of the substrate carrier 204
occurs with substantially zero velocity and acceleration in the
z-direction (curve C2). Likewise, because lift assembly 604
velocity in the x-direction is constant and matched to that of the
conveyor 106A during carrier exchange (curve C1), transfer of the
substrate carrier 204 occurs with substantially zero acceleration
in the x-direction. Further, the only motion occurring in the
y-direction during substrate carrier transfer is to accommodate the
constant radius of curvature of the transfer station 102A. However,
since both the lift assembly 604 and conveyor 106A follow
substantially the same path, the relative motion in the y-direction
is zero between the lift assembly 604 and conveyor 106A.
Accordingly, substrate carrier transfer may be performed with
substantially zero relative acceleration in three directions and
substantially zero relative velocity in at least two directions.
Following time T9, the lift assembly 604 decelerates (curve C1) to
the steady state speed of the TLA 206.
[0087] With reference to FIGS. 10C-D and curves C1-C4, the lift
assembly 604 may perform similar raisings, lowerings, and
accelerations as described above with reference to an unload
operation. For example, after receiving a signal to perform an
unload operation, the lift assembly 604 via the TLA 206 is
accelerated to match the velocity of the conveyor 106A in the
x-direction (curve C1') between times T1 and T2. Thereafter,
between times T3 and T4, the lift assembly 604 is raised (curve
C3') so that the kinematic features 626 engage the bottom of the
substrate carrier 204 to be unloaded from the conveyor 106A. At
time T4, the lift assembly 604 stops raising as the kinematic
features 626 engage the bottom of the carrier 204 (curves C2' and
C3'). Between times T4 and T5, the lift assembly 604 is raised
further so as to lift the flange of the substrate carrier 204 off
of the cradle 202. The substrate carrier 204 thereby is unloaded
from the cradle 202 with substantially zero relative velocity
and/or acceleration (e.g., in the x, y and/or z-directions due to
the halting of z-axis motion at time T4 prior to lifting the
substrate carrier 204 from the cradle 202 and due to speed matching
between the lift assembly 604 and the conveyor 106A). Following
time T5, the lift assembly 604 decelerates and reaccelerates (curve
C1') and lowers (curve C3') to clear the cradle 202 as previously
described and as shown in FIGS. 10C-D.
[0088] Accordingly, unloading/loading of substrate carriers
from/onto a moving conveyor may occur with substantially zero
relative velocity and/or acceleration in one or more directions,
more preferably in two directions, and most preferably in all
directions. Substantially zero velocity and acceleration in a
vertical direction are preferred; and zero velocities and/or
accelerations, rather than substantially zero velocities and/or
accelerations, during unloading/loading are more preferred. As used
herein, "zero velocity" or "zero acceleration" mean as close to
zero as possible given system variations such as conveyor height,
conveyor speed, actuator repeatability, etc., system limitations
such as controller resolution, actuator resolution, TLA position
tolerances, etc., and/or the like. "Substantially zero velocity" or
"substantially zero acceleration" mean sufficiently close to zero
so that a substrate carrier may be unloaded from and/or loaded onto
a moving conveyor and/or cradle without damaging a substrate
contained within the substrate carrier and/or generating
potentially damaging particles. For example, a substrate carrier
may be contacted with a relatively small velocity. In one
embodiment, a lift assembly may raise vertically rapidly, and then
slow down to a relatively small or substantially zero velocity
prior to contacting a substrate carrier. A similar small (or
substantially zero) acceleration also may be employed. Similar load
operations may be performed. In one embodiment, substrates or
substrate carriers are contacted in a vertical direction with less
than about 0.5 G of force, and in another embodiment with less than
about 0.15 G of force. Other contact force values may be
employed.
[0089] While the present invention has been described primarily
with reference to unloading/loading substrate carriers that contain
only a single substrate or a small lot carrier from/onto a moving
conveyor, it will be understood that substrate carriers that
contain multiple substrates similarly may be unloaded from or
loaded onto a moving conveyor. Further, the present invention may
be employed within systems that transport both single substrate
carriers and multiple substrate carriers (e.g., 25 substrate
carrier front opening unified pods). Likewise, the present
invention may be employed to unload individual substrates from
and/or load individual substrates onto a moving conveyor (e.g.,
substrates that are not contained within a closed substrate
carrier). For example, substrates may be transported via a conveyor
using an open substrate carrier, a substrate support, a substrate
tray or another substrate transport device that allows the lift
assembly 604 (or a modified version thereof) to directly place a
substrate on or remove a substrate from the substrate transport
device of the conveyor using similar lift assembly movements and/or
motion profiles. In some embodiments, the transfer station may be
located adjacent a storage rack or processing tool station.
Individual substrates may be transferred from a conveyor via a
transfer station to a docking station or other load port, or
directly into a load lock chamber and/or processing tool if
desired. For example, a substrate may be transferred directly from
the lift assembly 604 to a substrate handling robot of a factory
interface and/or processing tool (e.g., via a direct "lift
platform-to-end effector" transfer or via an intermediate transfer
location). Multiple individual substrates similarly may be
unloaded/loaded from/onto a moving conveyor.
[0090] The present invention makes it possible to unload individual
substrates and/or substrate carriers from a conveyor, to load
individual substrates and/or substrate carriers onto a conveyor,
and to transfer individual substrates and/or substrate carriers
from one conveyor to any number of other conveyors, without
stopping the conveyors. Consequently, the conveyors can run
continuously during operation of the Fab. These features provide
more efficient operation of the Fab, including a reduced total
elapsed time for fabricating each substrate, reduced work in
progress for a given level of substrate throughput, and a lower
manufacturing cost per electronic device produced in the Fab.
[0091] The foregoing description discloses only particular
embodiments of the invention; modifications of the above disclosed
methods and apparatus which fall within the scope of the invention
will be readily apparent to those of ordinary skill in the art. It
will be understood that the invention may be employed with any type
of substrates such as a silicon substrate, a glass plate, a mask, a
reticule, etc., whether patterned or unpatterned; and/or with
apparatus for transporting and/or processing such substrates.
[0092] Accordingly, while the present invention has been disclosed
in connection with specific embodiments thereof, it should be
understood that other embodiments may fall within the spirit and
scope of the invention, as defined by the following claims.
* * * * *
References