U.S. patent application number 10/702998 was filed with the patent office on 2004-05-13 for methods for transporting wafers for vacuum processing.
Invention is credited to Barker, David A., Kitazumi, Barry, Kuhlman, Michael J., Niewmierzycki, Leszek, Setton, David A., Tabrizi, Farzad.
Application Number | 20040091349 10/702998 |
Document ID | / |
Family ID | 22075066 |
Filed Date | 2004-05-13 |
United States Patent
Application |
20040091349 |
Kind Code |
A1 |
Tabrizi, Farzad ; et
al. |
May 13, 2004 |
Methods for transporting wafers for vacuum processing
Abstract
A workpiece handling system with dual load locks, a transport
chamber and a process chamber. Workpieces may be retrieved from one
load lock for processing at vacuum pressure, while workpieces are
unloaded from the other load lock at the pressure of the
surrounding environment. The transport chamber has a transport
robot with two arms. Processed workpieces and new workpieces may be
exchanged by a simple under/over motion of the two robot arms. The
transport robot rotates about a central shaft to align with the
load locks or the process chamber. The robot may also be raised or
lowered to align the arms with the desired location to which
workpieces are deposited or from which workpieces are retrieved.
The two load locks may be positioned one above the other such that
a simple vertical motion of the robot can be used to select between
the two load locks. The two load locks and transport robot allow
almost continuous processing. Additional process chambers may be
added to the transport chamber to further increase throughput. Each
stage of the workpiece handling system may also be designed to
handle multiple workpieces, such as two side by side workpieces.
Throughput is increased while allowing shared machinery to be used.
Linear and rotational doors may be used for the load locks to
provide a simple, compact design.
Inventors: |
Tabrizi, Farzad; (Danville,
CA) ; Kitazumi, Barry; (Milpitas, CA) ;
Barker, David A.; (Walnut Creek, CA) ; Setton, David
A.; (Alameda, CA) ; Niewmierzycki, Leszek;
(San Jose, CA) ; Kuhlman, Michael J.; (Fremont,
CA) |
Correspondence
Address: |
WILSON SONSINI GOODRICH & ROSATI
650 PAGE MILL ROAD
PALO ALTO
CA
943041050
|
Family ID: |
22075066 |
Appl. No.: |
10/702998 |
Filed: |
November 5, 2003 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10702998 |
Nov 5, 2003 |
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09651453 |
Aug 30, 2000 |
|
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|
6647665 |
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09651453 |
Aug 30, 2000 |
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09200660 |
Nov 25, 1998 |
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6315512 |
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60067299 |
Nov 28, 1997 |
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Current U.S.
Class: |
414/804 ;
414/806 |
Current CPC
Class: |
Y10S 414/139 20130101;
H01L 21/67196 20130101; H01L 21/67126 20130101; H01L 21/67754
20130101; Y10S 414/135 20130101; H01L 21/67781 20130101; H01L
21/67745 20130101; H01L 21/67201 20130101; H01L 21/67178 20130101;
H01L 21/67742 20130101 |
Class at
Publication: |
414/804 ;
414/806 |
International
Class: |
B66C 017/08 |
Claims
We claim:
1. A method for processing semiconductor wafers comprising:
providing a first load lock and a second load lock above the first
load lock; providing a transport robot in a transport chamber;
providing a processing chamber adjacent to the transport chamber;
maintaining the transport chamber at a first pressure; providing an
external robot outside of the transport chamber in an environment
having a second pressure; adjusting the vertical position of the
transport robot to select between the first load lock and the
second load lock; removing at least one semiconductor wafer from
the load lock selected by the transport robot and using the
transport robot to transfer the semiconductor wafer to the
processing chamber; and using the external robot to access the load
lock that is not selected by the transport robot
2. The method of claim 1, wherein the step of removing at least one
semiconductor wafer from the load lock selected by the transport
robot further comprises removing at least two semiconductor wafers
at a time from the load lock selected by the transport robot.
3. The method of claim 1, wherein the transport robot has a first
arm and a second arm.
4. The method of claim 3, wherein the step of removing at least one
semiconductor wafer from the load lock selected by the transport
robot further comprises using the first arm to remove the at least
one semiconductor wafer.
5. The method of claim 4, further comprising placing at least one
semiconductor wafer in the load lock selected by the transport
robot using the second arm.
6. The method of claim 3, wherein the step of removing at least one
semiconductor wafer from the load lock selected by the transport
robot further comprises removing at least two semiconductor wafers
at a time using the first arm of the transport robot.
7. The method of claim 6, further comprising placing at least two
semiconductor wafers at a time in the load lock selected by the
transport robot using the second arm.
Description
1. REFERENCE TO RELATED APPLICATIONS
[0001] The present application is a continuation of co-pending U.S.
application Ser. No. 09/651,453, filed Aug. 30, 2000 which has been
allowed and will issue Nov. 18, 2003 as U.S. Pat. No. 6,647,665,
which is a divisional of U.S. Pat. No. 6,315,512, which claims
priority from U.S. provisional application No. 60/067,299 filed
Nov. 28, 1997, now abandoned. Provisional application No.
60/067,299 is hereby incorporated herein by reference in its
entirety.
2. FIELD OF THE INVENTION
[0002] The field of the present invention relates in general to
vacuum processing of workpieces. More particularly, the field of
the invention relates to systems and methods for low contamination,
high throughput handling of workpieces including processing at a
pressure different from atmospheric. Examples of such workpieces
might include semiconductor wafers or flat panels for displays for
which vacuum processing is usually required.
3. BACKGROUND OF THE INVENTION
[0003] The increased cost for semiconductor manufacturing equipment
and factory floor space has driven equipment vendors increasingly
to compete on the productivity of their products and thus to have
to increase the number of workpieces, such as wafers, that can be
processed in any piece of such equipment per hour (throughput).
There are three central factors that determine workpiece
throughput: the time spent actually processing the workpieces (e.g.
removing photoresist, implanting ions, etc.), the number of
workpieces that can be simultaneously processed, and the amount of
time that elapses between removing processed workpieces from a
processing chamber and inserting unprocessed workpieces into the
chamber.
[0004] In some conventional workpiece processing systems, there may
be a significant delay between the time when processed workpieces
are removed from a process chamber and the time when the new
unprocessed workpieces are provided to the process chamber. For
instance, some systems use a single robot arm to remove and insert
workpieces. The robot arm must first align with the processed
workpiece, remove the processed workpiece from the processing
chamber, move to align with a storage area for processed workpieces
(which may involve a 180 degree rotation), deposit the processed
workpiece, move to align with a storage area containing unprocessed
workpieces, retrieve an unprocessed workpiece, move to align with
the processing chamber (which may involve a 180 degree rotation)
and deposit the unprocessed workpiece in the processing chamber.
The cumulative time required for all such steps may be large
resulting in a substantial delay between the time when a processed
workpiece is removed from the processing chamber and the time when
a new unprocessed workpiece is provided to the processing chamber.
In addition, each time that a batch containing a given number of
workpieces is processed, these workpieces must be removed through a
load lock to transit the pressure differential between atmosphere
and process pressure and a new batch must be loaded into the
processing environment. The time required for removing and loading
batches and for pressurizing or evacuating the load lock also
decreases throughput.
[0005] One system that has been designed to overcome some of the
disadvantages of conventional systems is the currently available
Aspen.TM. system available from Mattson Technology, Inc. which is
used to process semiconductor workpieces. In the current Aspen.TM.
system, a workpiece handling robot has two pairs of workpiece
support paddles facing in opposite directions as shown in FIG. 1.
Two new workpieces are loaded on the paddles on one side of the
robot. Then two processed workpieces are removed from the process
chamber on the paddles on the opposite side of the robot. The robot
rotates once and then deposits the new workpieces in the process
chamber and puts the processed workpieces back in the cassette
which may hold from 13 to as many as 26 workpieces. Once a cassette
of workpieces is processed, the cassette is removed and a new
cassette is provided through the load lock mechanism shown in FIG.
2. As shown in FIG. 2, a rotation mechanism is used to exchange
cassettes quickly in an outer load lock indicated at 202.
[0006] Another system designed to overcome some of the
disadvantages of conventional systems is shown in FIGS. 3A and 3B
and is described in U.S. Pat. No. 5,486,080. In this system two
separate robots 62 and 64 move independently of one another to
transport workpieces between an implantation station 25 and load
locks 22aand 22b. An intermediate transfer station 50 is used to
transfer the workpieces. FIG. 3B is a workpiece path diagram
showing the transport steps used to move workpieces in the system.
While a first robot transports an unprocessed workpiece from the
transfer station 50 to the implantation station 25, a second robot
transports a processed workpiece from the implantation station 25
to one of the load locks 22a or 22b. While one load lock is being
used for processing, the other load lock can be pressurized,
reloaded and evacuated.
[0007] While the above systems improve throughput and decrease down
time for pressurizing and evacuating load locks, reductions in
system size, complexity, and cost while maintaining or improving
throughput are still needed. For instance, the system of FIGS. 3A
and 3B uses two separate robots and a transfer station all of which
take up space. However, it is desirable to decrease the size of
workpiece processing systems to the extent possible, because the
clean room area used for the system is very expensive to maintain.
In addition, separate drive mechanisms which may be used for the
two robots would be expected to be more complicated and expensive
than a system that employs only one drive mechanism.
[0008] In addition to throughput, size, complexity and cost, a
fundamental constraint on workpiece handling systems is the
necessity to avoid contaminating workpieces. Very small amounts of
contaminants, such as dirt or dust can render a workpiece unusable
and the size and number tolerance for particulate contaminants
continues to decrease as workpiece geometries decrease. Workpiece
processing equipment may introduce contaminants in a variety of
ways. For example, particles may be shed when two pieces of
machinery rub or touch. It is important to minimize the exposure of
the workpieces to such contaminants during handling and
processing.
[0009] It is a particular challenge to design doors that minimize
particles generated by friction. Doors open and close to allow
workpieces to pass between the ambient (usually a clean room
environment) to a sealed (and possibly evacuated) chamber or
between two chambers. Opening and closing the doors may involve
mechanical mechanisms that create particles or may generate
particles when two surfaces are pushed together to close the door.
It is desirable to decrease the number of particles generated by
such doors to reduce the likelihood of contaminating workpieces. In
addition to avoiding contamination, it is desirable in many
instances to use a door that does not occupy much space, thereby
reducing the overall size of the system and conserving valuable
clean room space.
[0010] In summary, there is a need for a workpiece handling system
with high throughput but that does not entail relatively
complicated or expensive mechanisms, or mechanisms that occupy a
relatively large amount of space. There is a further need for a
workpiece processing system with reduced particle generation and
workpiece contamination. Without limiting the foregoing, there is a
need for door assemblies for use in such systems which reduce the
potential for contamination and occupy a relatively small space.
Preferably a workpiece handling and processing system would satisfy
all of the foregoing needs.
SUMMARY OF THE INVENTION
[0011] Aspects of the present invention provide a workpiece
processing system including multiple load locks, a workpiece
transfer chamber and one or more process chamber(s). In these
aspects of the invention, the core of the system consists of the
aforementioned multiple load lock stations, which may be stacked
vertically and act as buffers between a workpiece handler at
atmospheric pressure and another workpiece handler at another
pressure typically closer to the pressure at which the processes
are done. In another embodiment each load lock may function
independently from the other(s). Hence, one may be open to
atmosphere where a handler unloads or reloads workpieces while
other(s) operate, for example, impartial vacuum, allowing a vacuum
handler to supply workpieces to and from the process chamber(s).
Additionally, the load locks may provide the capability to cool
post process workpieces prior to or during their pressure
transition from the reduced pressure of the load lock to
atmospheric pressure. This functional independence makes such a
system capable of providing a steady supply of pre-processed
workpieces for the vacuum handler thus achieving high throughput in
nearly continuous workpiece processing.
[0012] In another embodiment, a controlled mini-environment can be
created on the atmospheric side of the load locks to provide a
clean, particle free volume for loading or unloading workpieces.
Air filtration systems and/or laminar flow hoods can be
incorporated for the purpose of contamination control. Multiple
workpiece-holder docking stations can be mounted to the enclosure,
creating a supply of pre-processed workpieces to the system.
[0013] In another embodiment, a robotics handler can operate in the
mini-environment and bring workpieces from their holders (which may
be called cassettes) to the load locks and back again. This handler
can utilize any combination of compound or individual rotational,
vertical, and horizontal movements to selectively align with the
workpiece cassettes or load locks for the purpose of transferring
workpieces. The robot handler can have two sets of paddles, or
other devices intended for retaining the workpieces during said
transport. One set may consist of multiple, vertically stacked
paddles, while the other may be a single paddle situated below the
others. Each set is capable of independent or dependent linear
motion such that any combination of the two can be used to
transport workpieces to and from the load locks. Additional
components can be mounted to the robot, or be made accessible in
the mini-environment. These stations could provide operations such
as workpiece identification or any other pre- or post-process
inspection.
[0014] In another embodiment, a linear door mechanism may be used
to seal one doorway of each load lock. An extractable door plate
contained in a housing may be extended against the doorway for
sealing or retracted for unsealing. The door plate and housing may
then be raised or lowered to provide access for workpieces to pass
through the doorway. If load locks are positioned above one
another, the door of the upper load lock might raise when opened
and, conversely, the lower door might drop to provide a pathway for
workpiece transfer.
[0015] In another embodiment, dual or multiple load locks can be
stacked vertically to minimize the system footprint. Each load lock
may contain shelves adjacent to which workpieces can be placed and
staged. These shelves may be situated such that workpieces are
contained next to and on top of one another. Workpiece temperature
could be controlled through thermal contact with the shelves which
may be heated or cooled by gaseous conduction and radiation. Gases
might also be directed over the workpieces, prior to or after
processing, to achieve desired temperatures.
[0016] In another embodiment, a rotational door may be used to seal
the other doorway of each load lock. This door may be extended
against the doorway for sealing or retracted for unsealing. Once
decoupled from the doorway, the door may rotate up or down to allow
workpieces to pass through. The door of the upper load lock may
rotate upward when opened and the lower load lock door may rotate
downward. The compactness of the door's operation allows for
vertically stacked load locks occupying minimal space.
[0017] In one embodiment a robot handler residing in a central
transfer chamber, with pressure closer to process chamber pressure
than atmospheric pressure may be utilized to transport workpieces
from the load locks to the process chamber(s) and back to the load
locks after processing. Such duties may be shared by two robotic
arms utilizing common compound or individual vertical and
rotational movements, but acting independently when extending or
retracting to pick or place workpieces. Additionally, two or
possibly more workpieces may be located side by side on paddles or
other devices fixed to each robot arm. Furthermore, the robots may
operate in an over/under fashion to reduce their geometrical
profile and minimize the transfer time of post- and pre-processed
workpieces. The robot arm structure can be made to avoid any
bearing surfaces passing directly over a workpiece and thus helping
ensure cleaner, lower-particle-on workpiece contamination during
operation.
[0018] In another embodiment, a slit door could be used to isolate
the process chamber environment from that of the transfer chamber.
Such a door could work utilizing vertical motions to allow passage
of workpieces through the process chamber doorway. Small horizontal
motion could be used to seal or unseal the door from the doorway.
Both motions allow for a very compact door and contribute to
minimizing the footprint of the system. Such a door could be made
to seal off positive pressure in the process chamber while the
transfer chamber operated at negative pressure. In another
embodiment, a process chamber could be serviced at atmospheric
pressure while the transfer chamber remained at partial or
near-vacuum.
[0019] In another embodiment, the transfer chamber could be
designed to dock three or more process chambers, each capable of
processing two or more workpieces side by side. Each process
chamber could be designed as a modular entity, requiring a minimum
amount of effort to mount to and communicate with the main transfer
chamber and its elements. Additionally, multiple process chambers
mounted to the transfer chamber might each provide the same or
different process capability.
[0020] In another embodiment, pre- or post-process stations could
be located in the transfer chamber and made accessible to the
vacuum robot handler. Examples of such processes include, but are
not limited to, preheating or cooling of workpieces and workpiece
orientation and alignment.
BRIEF DESCRIPTION OF THE DRAWINGS
[0021] These and other features and advantages of the present
invention will become more apparent to those skilled in the art
from the following detailed description in conjunction with the
appended drawings in which:
[0022] FIG. 1 illustrates the workpiece transport path of a prior
art workpiece handling system.
[0023] FIG. 2 illustrates a load lock transfer system of a prior
art workpiece handling system.
[0024] FIG. 3A illustrates a prior art workpiece handling system
with two robots.
[0025] FIG. 3B illustrates the workpiece transport path in the
prior art system of FIG. 3A.
[0026] FIG. 4 is a simplified side cross-sectional view of a
workpiece handling system according to an exemplary embodiment of
the present invention.
[0027] FIG. 5 is a simplified top cross-sectional view of a
workpiece handling system according to an exemplary embodiment of
the present invention.
[0028] FIG. 6A is a top, front perspective view of a workpiece
handling system according to an exemplary embodiment of the present
invention.
[0029] FIG. 6B is a top, rear perspective view of a workpiece
handling system according to an exemplary embodiment of the present
invention.
[0030] FIG. 7A is a top plan view of a vacuum transfer robot
according to an exemplary embodiment of the present invention.
[0031] FIG. 7B is a top, rear perspective view of a vacuum transfer
robot according to an exemplary embodiment of the present
invention.
[0032] FIG. 8A is a top plan view of a rotational door according to
an exemplary embodiment of the present invention.
[0033] FIG. 8B is a simplified side view of load locks having
rotational doors in a closed position according to an exemplary
embodiment of the present invention.
[0034] FIG. 8C is a simplified side view of load locks having
rotational doors in an open position according to an exemplary
embodiment of the present invention.
[0035] FIG. 8D is a simplified side view illustrating the
rotational and linear motions used to open and close rotational
doors according to an exemplary embodiment of the present
invention.
[0036] FIG. 9A is a top plan view of a linear door assembly
according to an exemplary embodiment of the present invention.
[0037] FIG. 9B is a simplified side view of a linear door assembly
according to an exemplary embodiment of the present invention.
[0038] FIG. 9C is a top cross-sectional view of a linear door
assembly according to an exemplary embodiment of the present
invention.
[0039] FIG. 9D is a side view of a linear door assembly according
to an exemplary embodiment of the present invention.
[0040] FIG. 10A is a side cross-sectional view of a linear door
assembly according to an alternate embodiment of the present
invention.
[0041] FIG. 10B is a side cross-sectional view of a linear door
assembly according to an alternate embodiment of the present
invention.
[0042] FIG. 11 illustrates a side view of a rotary mechanism.
[0043] FIG. 12 illustrates an alternative embodiment of a rotary
mechanism.
DESCRIPTION
[0044] The following description is presented to enable any person
skilled in the art to make and use the invention. Descriptions of
specific designs are provided as examples. Various modifications to
the embodiment will be readily apparent to those skilled in the
art, and the generic principles defined herein may be applied to
other embodiments and applications without departing from the
spirit and scope of the invention. Thus, the present invention is
not intended to be limited to the embodiment shown, but is to be
accorded the widest scope consistent with the principles and
features disclosed herein.
[0045] FIG. 4 is a simplified side cross-sectional view of a
semiconductor workpiece handling system, generally indicated at
400, according to an embodiment of the present invention. As shown
in FIG. 4, system 400 includes a workpiece cassette holder 402
which may be in a clean room environment, an atmospheric robot 404,
an upper load lock 406a, a lower load lock 406b, a vacuum transport
chamber 408 and a process chamber 410. System 400 allows workpieces
to be transported from cassette holder 402 to process chamber 410
for processing using a compact and simplified load lock and
robotics design with high throughput and a low potential for
contamination. Cassettes of workpieces to be processed are
initially provided at cassette holder 402. Atmospheric robot 404
includes one or more paddle(s) 412 for supporting and transporting
workpieces and a shaft 414 for rotating and/or raising or lowering
paddle(s) 412. When the robot retrieves workpieces from a cassette,
the shaft is rotated and positioned so paddle(s) 412 faces the
cassette. Paddle(s) 412 extends horizontally to retrieve one or
more workpieces and then retracts with the workpieces on paddle(s)
412. Shaft 414 then rotates and moves so paddle(s) 412 face load
locks 406a and 406b. The shaft is raised or lowered to align the
paddle with shelves in either load lock 406a or 406b in the course
of which all motions due to independent control may occur
simultaneously or in sequence. Generally, at any given time one of
the load locks will be open to atmospheric robot 404, while
workpieces in the other load lock are being processed at vacuum
pressures. Paddle(s) 412 then may extend horizontally to deposit
the workpiece(s) in the appropriate load lock. Atmospheric robot
404 also removes workpiece(s) from the load locks and deposits the
processed workpiece(s) in a cassette in a similar manner.
[0046] The load locks contain one or more shelves 416a and 416b to
hold workpieces. The shelves may be cooled to provide a cooling
station for workpieces after processing. In alternate embodiments,
a cassette-like holder may be loaded into the load lock rather than
providing a shelf or shelves in the load lock. The load locks are
sealed on the outside by linear doors 418a and 418b. The top linear
door 418a may be raised to expose an opening through which
workpieces may be loaded into, or unloaded from, upper load lock
406a. The bottom linear door 418bmay be lowered to expose a similar
opening through which workpieces may be loaded into, or unloaded
from, lower load lock 406b.
[0047] After atmospheric robot 404 removes processed workpieces
from a load lock and reloads it with new workpieces, the linear
door is closed and the load lock is evacuated to vacuum pressure to
match the pressure of the vacuum transport chamber 408. A
rotational door 420a or 420b is then opened to allow a vacuum
transport robot 422 to access the workpieces. An upper rotational
drive (not shown) moves upper rotational door 420a linearly a
slight distance away from the inner wall 424a of the upper load
lock and rotates it. The rotational drive raises or lowers the door
to expose an opening through which workpieces may be retrieved from
shelves 416a before processing and returned after processing. A
lower rotational drive (not shown) moves lower rotational door 420b
in a similar manner back and upward or downward from wall 424b to
allow access to workpieces in lower load lock 406b.
[0048] The dual load lock system shown in FIG. 4 allows almost
continuous processing without significant down time for providing
new workpieces from the atmospheric clean room to the vacuum
processing environment. When workpieces are being loaded into one
of the load locks (for example upper load lock 406a), the other
load lock 406b is at vacuum pressure. For the upper load lock 406a,
linear door 418awould be open and atmospheric robot 404 would
remove processed workpieces and reload the load lock with new
workpieces. Rotational door 420a would be closed to provide a seal
against the vacuum pressure of vacuum transport chamber 408. At the
same time, rotational door 420b would be open and linear door 418b
would be closed to allow workpieces in lower load lock 406b to be
accessed for processing.
[0049] After loading, linear door 418a is closed and upper load
lock 406a is evacuated by a vacuum pump (not shown). When the
appropriate pressure is obtained, rotational door 420a may be
opened. In order to allow near continuous processing, upper load
lock 406a may be evacuated and rotational door 420a may be opened
before or just as the penultimate processed workpiece is returned
to lower load lock 406b. A new workpiece from upper load lock 406a
is then exchanged with the last processed workpiece in process
chamber 410 which is returned to lower load lock 406b. The
rotational door 420b is then closed and the pressure in lower load
lock 406b is raised to equilibrium with the surrounding environment
(which may be a clean room at atmospheric pressure). Linear door
418b is then opened and atmospheric robot 404 removes processed
workpieces and reloads new workpieces in lower load lock 406b. The
process then continues such that new workpieces are always or
nearly always available from one of the load locks for processing
in the vacuum environment.
[0050] The vacuum transport robot 422 retrieves new workpieces from
whichever load lock is open and places the workpieces in process
chamber 410 for processing. The vacuum transport robot 422 also
removes processed workpieces from process chamber 410 and returns
them to the respective load lock. Vacuum transport robot 422 is
designed to minimize the transport time required to remove a
processed workpiece from, and reload a new workpiece into, the
process chamber 410. The transport time is down time for process
chamber 410 which reduces throughput, so it is important to keep
the transport time short.
[0051] The transport robot has one or more upper paddle(s) 426a and
lower paddle(s) 426b for supporting and transporting workpieces and
a shaft 428 for rotating and/or raising or lowering the paddles.
The robot has upper arms 430a and lower arms 430b affixed to a
four-bar linkage for extending and retracting paddles 426a and
426b, respectively. For purposes of the following discussion, it
will be assumed that rotational door 420a is open and that new
workpieces are available in upper load lock 406a, although it is
understood that a similar process is used when workpieces are
available in lower load lock 406b. Initially, it is assumed that
the last workpiece from lower load lock 406b is being processed in
process chamber 410 and that the second to last processed workpiece
was just returned to lower load lock 406b. At this time, both upper
and lower rotational doors 420a and 420b are open and upper load
lock 406a contains new workpieces to be processed. Shaft 428 is
then raised to align one of the paddles (for example upper paddle
426a) with a new workpiece on a shelf in upper load lock 406a. Arm
430a then extends and paddle 426a retrieves a new workpiece from
the upper load lock. The arm 430a then retracts and shaft 428
rotates 180 degrees so the arms and paddles face the process
chamber. Both arms are fully retracted when the shaft rotates. This
minimizes the rotation diameter and allows a relatively compact
transport chamber to be used. This is particularly desirable when
300 millimeter or larger workpieces are being handled. After
rotation, the shaft is raised or lowered as necessary to align
paddle 426b with the processed workpiece in process chamber 410. Of
course, in some embodiments, this alignment may occur prior to or
during rotation. The processed workpiece may remain at or near a
process station 432 for removal or, in some process chambers, the
workpiece may be raised on pins or other mechanisms for removal. A
door 434 may be opened to allow the processed workpiece to be
removed and a new workpiece to be placed in the process chamber.
The door may be a linear or rotational door as described above or
may be a conventional door system. The door 434 may be opened as
the transport robot 422 rotates and aligns, so there is no extra
delay (or the robot may be fully rotated and aligned prior to
completion of processing, in which case the door is opened at the
completion of processing).
[0052] Arm 430b then extends and paddle 426b retrieves the
processed workpiece. Arm 430b then retracts and shaft 428 is
lowered to align paddle 426a with the desired position for
depositing a new workpiece in the process chamber. Arm 430a extends
and a new workpiece is deposited in process chamber 410 from paddle
426a. Arm 430a then retracts. The shaft then rotates 180 degrees
with both arms in the retracted position.
[0053] Shaft 428 is then lowered or raised to align with the
respective shelf in lower load lock 406b. Arm 430b extends and
returns the last processed workpiece to lower load lock 406b. Arm
430b retracts and rotational door 420b is closed. The pressure in
lower load lock 406b is then raised so the processed workpieces can
be removed as described above. Shaft 428 then raises paddle 426a to
align with a new workpiece in upper load lock 406a. Arm 430a
extends, picks up and retracts with a new workpiece. Transport
robot 422 rotates and the empty lower paddle 426b is aligned to
retrieve the processed workpiece from process chamber 410. When
processing is complete, door 434 opens and arm 430b extends and
retracts with the processed workpiece. The new workpiece is then
deposited in the process chamber as described above. The robot
rotates again and arm 430b extends and retracts to deposit the
processed workpiece on the applicable shelf of upper load lock
406a. Arm 430a extends and retracts to obtain a new workpiece and
the process continues until the last workpiece from upper load lock
406a is in process chamber 410. By that time, lower load lock 406b
has been unloaded and reloaded with new unprocessed workpieces and
then pumped down, after which lower rotational door 420b is
opened.
[0054] FIG. 5 is a top cross-sectional view of a workpiece handling
system according to an embodiment of the present invention which
allows for dual side-by-side workpiece processing. The robots, load
locks and process chamber are all designed to handle two (or
possibly more) workpieces at a time. As a result, a significant
amount of the machinery and control mechanisms are shared while
throughput is doubled (or more). As shown in FIG. 5, two or more
workpiece cassette holders 402 and 502 may be provided
side-by-side. Atmospheric robot 404 may be positioned on a track
505 which allows the robot to move horizontally to align with
either cassette holder 402 or 502. Upper load lock 406a and lower
load lock 406b (not shown in FIG. 5) each have side by side
positions for workpieces on each of the shelves 416a or 416b (not
shown in FIG. 5). Transport robot 422 has dual paddles on each arm
430a and 430b. Upper arm 430a supports paddles 426a and 526a. Lower
arm 430b supports paddles 426b and 526b. The robot is thereby
capable of depositing or retrieving two workpieces at a time from
shelves 416a or 416b. For instance, arm 430b may extend to deposit
two processed workpieces in a respective load lock. Shaft 428 may
then be raised or lowered to align paddles 426a and 526a with new
workpieces on a different shelf. Arm 430a may then extend to
retrieve the two new workpieces for processing. Once both of the
arms are retracted, shaft 428 may rotate, so the paddles face the
process chamber 410. The process chamber is designed to contain at
least two process stations 432 and 532. Door 434 is raised and arm
430b extends to retrieve the two processed workpieces from the
process chamber 410. After arm 430b retracts with the processed
workpieces, the shaft is raised or lowered to align the new
workpieces with the desired position in the process chamber. Arm
430a then extends to deposit the new workpieces for processing. The
process continues as described above with two workpieces processed
at a time.
[0055] FIG. 6A is a top front perspective view and FIG. 6B is a top
back perspective view of a workpiece handling system according to
an embodiment of the present invention which illustrate portions of
a frame structure which may be used to support and expand the
workpiece handling system. As shown in FIGS. 6A and 6B cassette
holders 402 and 502 are part of a cassette auto loader system 602.
An operator interface panel 601 is provided adjacent to the auto
loader system 602 and another may be positioned on the main frame
assembly 608. The operator interface panel 601 allows an operator
to program the system and adjust operational parameters. It will be
understood that the various robots, doors and other mechanisms may
be controlled by programmable software executed by a processing
unit. Accordingly, the particular order and process steps used to
manipulate workpieces may be modified for a particular application
using software controls. For instance, it may be desirable in some
embodiments to have the upper paddles 426a and 526a handle
processed workpieces, so a robot arm does not pass over the
workpieces after processing which could expose the underlying
workpieces to shed particles. In such an embodiment, the software
would cause the lower arm 430b to be used for new workpieces prior
to processing. It will be readily apparent that any variety of
process steps and sequences may be implemented by modifying the
software controlling the robots, doors and other mechanisms.
[0056] In the embodiment shown in FIGS. 6A and 6B a
mini-environment 604 with a Hepa or Ulpa filter may positioned
between the auto loader system 602 and the load locks 406a and 406b
for atmospheric robot 404. The track 505 for the atmospheric robot
is also thereby contained in the mini-environment.
[0057] As shown in FIG. 6A, linear door 418a is raised to expose
slit 618a to access upper load lock 406a and linear door 418b is
lowered to expose slit 618b to access lower load lock 406b.
Although both doors are open in FIG. 6A for purposes of
illustration, normally only one door would be open at a time as
described above. The linear doors are aligned on rail 619 as shown
in FIG. 6B which allows the doors to be raised and lowered. The
linear doors are attached to load lock frame 606.
[0058] Upper rotational door 420a is also shown in the open
position in FIG. 6A for illustrative purposes, although as
described above normally doors 420a and 418a would not be open at
the same time. The rotational drive mechanism for opening the
rotational doors is positioned adjacent to load lock frame 606 as
shown at position 620 in FIGS. 6A and 6B. As will be described
further below, the rotational drive mechanism moves the rotational
door 420a linearly slightly back from the doorway prior to
rotation. Rotational door 420a is then rotated up (or down) to open
it. When it is closed, it is rotated down (or up) and then moved
linearly slightly forward to seal the opening. Lower rotational
door 420b uses a similar motion, although it is rotated down (or
up) when it is open. While the drive mechanisms and motions for
these doors is more complex than for the linear doors, they allow
for two very compact doors to be used one above the other for the
two load locks.
[0059] Main frame assembly 608 provides a support for transport
chamber 408. Transport robot 422 is shown in FIGS. 6A and 6B with
upper arm 430a extended into upper load lock 406a. Lower arm 430b
is retracted.
[0060] The transport chamber shown in FIGS. 6A and 6B supports
multiple process chambers through multiple docks. Process chamber
410 is connected to one of the docks and is supported by process
module frame 610. Additional docks are shown at 635 (in FIG. 6A)
and 636 (in FIG. 6B). An additional process chamber may be
connected to each dock 635 and 636. As shown in FIG. 6A, each dock
may be provided with slit door 634. With additional process
chambers attached to docks 635 and 636, as many as six workpieces
may be processed at a time. When process chambers are connected to
docks 635 and 636, a similar process to that described above is
used to load and unload workpieces, but the robot is programmed to
rotate only 90 degrees when aligning with the additional process
chambers. The processing may be staggered, so vacuum transport
robot 422 can remove and load workpieces in each process chamber
without delaying processing in the other chambers.
[0061] For instance, the robot may first rotate to align with a
process chamber at dock 635 and then remove two processed
workpieces and load two new workpieces. The robot then rotates 90
degrees back to the load locks to deposit the processed workpieces
and retrieve two new workpieces. The robot may then rotate 180
degrees to process chamber 410, remove two processed workpieces and
load the new workpieces. The robot then rotates 180 degrees back to
the load locks to deposit the processed workpieces and retrieve two
new workpieces. The robot then rotates 90 degrees to align with a
process chamber at dock 636, remove two processed workpieces and
load the new workpieces. The robot then rotates 90 degrees back to
the load locks to deposit the processed workpieces and retrieve two
new workpieces. The process then continues back to the process
chamber at dock 635. With such a configuration, a very high
throughput may be achieved.
[0062] In addition, if the process chambers at each dock were
different, the robot might be programmed to move workpieces from
one process chamber to another process chamber. For instance, it
may be desired to process new workpieces in a process chamber at
dock 635 and then move the processed workpieces from dock 635 to a
second process in process chamber 410. In such an embodiment, the
robot would retrieve workpieces from dock 635 and rotate 90 degrees
to process chamber 410 rather than returning to the load locks.
Workpieces from process chamber 410 may be removed and the
workpieces from dock 635 may be deposited using the under/over
transport robot arms 430a and 430b as described above. The robot
could then move the workpieces from process chamber 410 back to the
load lock, or in some embodiments, the workpieces may be moved to
dock 636 for further processing. Through programmable software
control any variety of processes may be supported with high
throughput.
[0063] FIG. 7A is a top plan view, and FIG. 7B is a top, rear
perspective view, of a vacuum transfer robot according to an
exemplary embodiment of the present invention. The robot is shown
with upper arm 430a extended and lower arm 430b retracted. As shown
in FIGS. 7A and 7B, upper arm 430a has four bars connected by
rotational joints. Thin base bar 702a is connected to shaft 428 by
rotational joint 712a. The other end of thin base bar 702a is
connected to rotational joint 716a. A wide base bar 704a is
adjacent on the inside of thin base bar 702a and is connected to
shaft 428 by rotational joint 714a. The other end of the wide base
bar 704a is connected to rotational joint 718a. Thin fore bar 706a
is connected to rotational joint 716a and extends to a split
support 725a which supports paddles 426a and 526a. Thin fore bar
706a is connected to split support 725a at rotational joint 720a. A
wide fore bar 708a is adjacent on the outside of thin fore bar 706a
and is connected to rotational joint 718a. The wide fore bar 708a
connects to the split support at rotational joint 722a.
[0064] A driving shaft may be directly coupled to wide base bar
704a through rotational joint 714a. Rotation of the shaft results
in an equal rotation of wide base bar 704a. An opposite rotational
movement is transmitted through wide base bar 704a into thin fore
bar 706a by counter rotating elements hard-coupled to each through
rotational joints 718a and 716a respectively. Both thin base bar
702a and wide fore bar 708a follow the rotation of wide base bar
704a and thin fore bar 706a, respectively. Hence, a purely linear
motion is provided to the split support 725a. The arrangement of
the bars ensures that the center of the split support stays aligned
so the paddles move linearly when they extend or retract.
[0065] Arm 430b has a similar structure. The corresponding parts
are labeled with the same number as used to describe arm 430a
except that a suffix of "b" has been used instead of "a". It will
be noted, however, that split support 725a is mounted above bars
706a and 708a while split support 725b is mounted below bars 706b
and 708b. It will also be noted that bars 706a and 708a are mounted
above rotational joints 718a and 716a which provides a clearance
for the lower split support 725b to pass under upper arm 430a. This
structure allows the arm to use an over/under motion to deposit and
retrieve workpieces. This structure also allows arm 430b to be
extended and retracted without passing paddles 426b and 526b
directly under any of the rotational joints of upper arm 430a. This
helps minimize the potential of shed particles from the rotational
joints from dropping onto workpieces supported by paddles 426b and
526b.
[0066] The operation of rotational doors 420a and 420b will now be
described with reference to FIGS. 8A-8D. FIG. 8A is a top view of
rotational door 420a in the closed position and portions of
rotational drive mechanism 620. The arrows indicate that a linear
motion and a rotational motion may be imparted on rotational door
420a by rotational drive mechanism 620. FIG. 8B is a side
cross-section of load locks 406a and 406b showing rotational doors
420a and 420b in the closed position. The rotational drive
mechanism has pushed the doors against inner walls 424a and 424b to
seal the doors closed. An o-ring or other mechanism may be provided
at the interface of the doors and inner walls to provide a seal.
FIG. 8C illustrates rotational doors 420a and 420b in the open
position. As indicated by the arrows, rotational drive mechanism
620 moves the doors linearly slightly away from inner walls 424a
and 424b and then rotates rotational door 420a up and rotational
door 420b down to open the doors. FIG. 8D is a side cross-sectional
view further illustrating the motions which may be imparted on
rotational door 420a. As shown in FIG. 8D, when the rotational door
420a is rotated to the closed position it may still be a short
distance from wall 424a. Rotational drive mechanism 620 can then
move the door linearly toward wall 424a to seal the door.
[0067] The advantage of having such rotational doors 420a and 420b
within the load locks comes from the fact that the load lock
pressure is often greater than that in the transfer chamber (during
workpiece loading/unloading to atmosphere) but never significantly
less than it. Therefore, this rotational door is held shut by the
pressure differential when the workpieces are being loaded or
unloaded from that load lock. This insures that the pressure seal
is well made and that the mechanism which translates the rotating
door does not bear a heavy load. Further, the door mechanism is
housed within the load lock and does not allow particles to fall
directly into the workpiece transfer chamber or onto the load lock
chamber below.
[0068] The motion of linear doors 418a and 418b are also shown in
FIGS. 8B and 8C. The linear doors will now be further described in
conjunction with FIGS. 9A-9D. FIG. 9A is a top cross-sectional view
of upper load lock 406a and a top view of linear door 418a. Linear
door 418a is mounted on a linear motion track or rail 619 along
which the door is guided when it is moved into open or closed
position. FIG. 9D is a side view of upper load lock 406a and linear
door 418a which shows rail 619. Linear door 418a further may
include sensor 901 to sense the presence or absence of workpieces.
When a workpiece is sensed, a signal is provided by the sensor 901
to a mechanism for sliding linear door 418a upward along rail 619
to a position that allows workpieces to pass through the doorway of
upper load lock 406a. The motion of the door in the embodiment
shown in FIG. 9D is accomplished by a pneumatic cylinder but it
will be appreciated that many alternatives, such as linear
bearings, lead screws, and motors also may be employed to move
linear door 418a.
[0069] FIG. 9B is a side cross-section of upper load lock 406a and
linear door 418a with arrows indicating the directions in which
linear door 418a may be moved. FIG. 9C is a top cross-section of
upper load lock 406a and linear door 418a which shows the mechanism
used to seal the door when it is closed. As shown in FIG. 9C,
linear door 418a includes door frame 902 which forms a recess. A
door plate 904 is positioned in the recess and is connected to the
door frame 902 by an extendable connector, such as spring 906. When
door frame 902 is lowered over the doorway, door plate 904 may be
extended to seal the door. When vacuum processing pressures are
used, the pressure differential may then cause door plate 904 to
seal the doorway. O-rings 908 or other mechanisms may be used to
provide a good seal. Electromagnets 910 may also be used to attract
door plate 904 and seal the doorway. In such embodiments, door
plate 904 could comprise a magnetic material capable of being
attracted to electromagnets 910 or such material could be mounted
to door plate 904, if it is non-magnetic, for the same result. Such
magnets could be mounted outside the o-ring seal such that they are
not in vacuum when the load lock is evacuated.
[0070] When workpieces have been loaded into the load lock and it
is desired to seal upper load lock 406a, the linear door 428a,
which is positioned above the doorway, is lowered to cover the
doorway. Electromagnets 910 are activated and door plate 904
extends toward the electromagnets to form a seal against o-rings
908. When it is desired to transfer workpieces out of upper load
lock 406a, upper load lock 406a is re-pressurized to equalize with
the pressure of the surrounding environment. If electromagnets 910
are being used, they are deactivated or made to provide a repelling
force. Spring 906 or other extension device in conjunction with the
repulsive electromagnetic force then retracts door plate 904 to
unseal the doorway. Linear door 418a is then raised along rail 619
to open the doorway and allow workpieces to be removed from upper
load lock 406a. It will be understood that a similar mechanism is
used for lower linear door 418b except that the door is lowered
when it is opened.
[0071] Many alternatives to the embodiment shown in FIGS. 9A-9D are
possible. For example, instead of an electromagnet, other devices
may be employed to extend door plate 904 to seal the doorway. As
shown in FIG. 10A, inflatable tube 1006 may be inflated to push
door plate 904 against the doorway. The inflatable tube 1006 is
deflated to unseal and open the door. As shown in FIG. 10B, a
pneumatic cylinder 1008 may also be used to push door plate 904
against, and retract door plate 904 from, the doorway. The ease
with which door plate 904 may be extended and retracted allows the
door to function as an over-pressure valve and a "back to
atmosphere" switch.
[0072] FIG. 11 illustrates a side view of rotary mechanism 620.
Rotary mechanism 620 is used to rotate and translate rotational
doors 420a and 420b for opening and sealing the system. The
mechanism operates on the outside of load locks 406a and 406b. The
following discussion describes mechanism 620 of the lower load lock
406b. A similar discussion applies to the mechanism of upper load
lock 406a. Rotational door 420b and shaft 421b are secured to slide
block 1101 and allowed to rotate therein. Outside slide block 1101,
rotary stop 1102 and gear 1103 are rigidly fixed to and rotate with
the shaft. The slide block 1101 is allowed to translate on linear
slide 1104 and is acted on by spring 1105 so that it rests against
hard stop 1106. Interacting with and engaging gear 1103 is a linear
rack 1107 which can translate on slide 1108 and is motivated by
piston 1109. As shown, linear rack 1107 is being pulled into piston
1109 such that rotary stop 1102 is pushed against block 1110. This
position of the mechanism places rotational door 420b in the
orientation shown in FIG. 8C. When piston 1109 pushes on linear
rack 1107, gear 1103 is rotated clockwise as are rotary stop 1102
and rotational door 420b. Spring 1105 reacts against any impending
translation of slide block 1101 and keeps it pushed against hard
stop 1106. Once rotary stop 1102 comes into contact with stop 1111,
rotary motion stops. Piston 1109, however, continues to push linear
rack 1107 into gear 1103. By virtue of rotational impedance, slide
block 1101 is translated on linear slide 1104 into spring 1105.
This motion is coupled to rotational door 420b which pushes against
a sealing mechanism the doorway and isolates lower load lock 406b
from vacuum transport chamber 408. In this mode, the door is
considered closed. Both slide block 1101 and the shaft of
rotational door 420b are sealed by means of O-rings or other
devices such as bellows to isolate lower load lock 406b from the
surrounding environment.
[0073] When rotational door 420b is opened, piston 1109 retracts.
In doing so, spring 1105 pushes slide block 1101 into hard stop
1106. Since there is no relative motion between linear rack 1107
and gear 1103 during this movement, pure translation is realized
and rotational door 420b moves away from the doorway and its seal.
Once slide block 1101 hard stops, linear rack 1107 continues to be
pulled by piston 1109 and rotational motion is imparted to
rotational door 420b through gear 1103. Finally, rotary stop 1102
makes contact with bock 1110 and rotation stops. Again, rotational
door 420b is now in the open position.
[0074] In alternative embodiments, piston 1109 could be replaced by
a motor driven lead screw or any other translational driving
mechanism. Linear rack 1107 and gear 1103 could interface through
friction and eliminate tooth contacts. Spring 1105 could be
replaced by a piston or inflatable bladder.
[0075] In another embodiment shown in FIG. 12, rotation and
translation could be controlled separately by linkage 1201 and
wedge 1202. Sensors on control pistons 1203 and 1204 could indicate
the position of the rotary door and coordinate the motions. To
close, piston 1203 would extend and rotate linkage 1201 counter
clockwise which is attached to rotational door 420a or 420b and is
contained in slide block 1101. Once proper position was achieved,
which could be through the use of a hard stop, control piston 1204
would extend pushing wedge 1202 into roller 1205. Since roller 1205
is fixed to slide block 1101, translation and sealing of rotational
door 420a or 420b to their respective doorways is achieved. To
open, control piston 1204 is retracted and spring 1105 pushes back
on slide block 1101. Once in proper horizontal position, piston
1203 retracts and rotates rotational door 420a or 420b to an open
position.
[0076] The foregoing description is presented to enable any person
skilled in the art to make and use the invention. Descriptions of
specific designs are provided only as examples. Various
modifications to the exemplary embodiments will be readily apparent
to those skilled in the art, and the generic principles defined
herein may be applied to other embodiments and applications without
departing from the spirit and scope of the invention. Thus, the
present invention is not intended to be limited to the embodiments
shown, but is to be accorded the widest scope consistent with the
principles and features disclosed herein.
* * * * *