U.S. patent application number 10/411750 was filed with the patent office on 2003-11-13 for planarization system with multiple polishing pads.
This patent application is currently assigned to Applied Materials, Inc.. Invention is credited to Sommer, Phillip R..
Application Number | 20030209320 10/411750 |
Document ID | / |
Family ID | 22682541 |
Filed Date | 2003-11-13 |
United States Patent
Application |
20030209320 |
Kind Code |
A1 |
Sommer, Phillip R. |
November 13, 2003 |
Planarization system with multiple polishing pads
Abstract
A chemical mechanical planarization system and method for
planarizing wafers is provided. The system generally includes a
transfer corridor, at least one corridor robot, one or more
polishing modules and at least one loading device. The corridor
robot is disposed in the transfer corridor and is positionable
between a first end and a second end of the transfer corridor. The
loading device is adapted to transfer workpieces between the
transfer corridor and the polishing modules. Generally, the loading
device includes at least one load cup. The one or more polishing
modules each include one or more polishing heads for holding
workpieces during processing.
Inventors: |
Sommer, Phillip R.; (Newark,
CA) |
Correspondence
Address: |
Patent Counsel
Applied Materials, Inc.
P.O. Box 450A
Santa Clara
CA
95052
US
|
Assignee: |
Applied Materials, Inc.
|
Family ID: |
22682541 |
Appl. No.: |
10/411750 |
Filed: |
April 10, 2003 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10411750 |
Apr 10, 2003 |
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09796303 |
Feb 27, 2001 |
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6562184 |
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60185812 |
Feb 29, 2000 |
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Current U.S.
Class: |
156/345.12 ;
156/345.22 |
Current CPC
Class: |
B24B 37/345 20130101;
H01L 21/67219 20130101; H01L 21/67751 20130101; H01L 21/67161
20130101; B24B 41/005 20130101; H01L 21/67766 20130101 |
Class at
Publication: |
156/345.12 ;
156/345.22 |
International
Class: |
H01L 021/306 |
Claims
What is claimed is:
1. A polishing system comprising: a plurality of polishing modules
arranged in a linear orientation; a substrate cleaner; and a first
robot positioned between the substrate cleaner and polishing
modules, the first robot laterally positionable in a direction
parallel to the linear orientation of the polishing modules and
adapted to transfer a substrate between at least two of the
plurality of polishing modules.
2. The polishing system of claim 1, wherein the plurality of
polishing modules further comprise four polishing heads, each
polishing head adapted to retain a substrate during processing.
3. The polishing system of claim 2, wherein the polishing modules
further comprise four load cups aligned parallel to the orientation
of the polishing modules, the load cups adapted to transfer
substrates between the polishing heads and the first robot.
4. The polishing system of claim 1 further comprising: factory
interface adapted to accept a plurality of substrate storage
cassettes; and a second robot disposed in the factory interface and
adapted to transfer substrates between the cassettes and the first
robot.
5. The polishing system of claim 1 further comprising a rail
disposed between the substrate cleaner and the plurality of
polishing modules, wherein the first robot is slidably coupled to
the rail and adapted to be selectively positioned along the
rail.
6. The polishing system of claim 5 further comprising a second
robot slidably coupled to the rail.
7. The polishing system of claim 1, wherein the substrate cleaner
has an orientation parallel to the orientation of the polishing
modules.
8. The polishing system of claim 4 further comprising: a third
robot disposed at an end of the substrate cleaner opposite the
factory interface.
9. A polishing system comprising: a plurality of polishing modules
defining a first linear orientation; four polishing heads adapted
to retain substrates during processing in the polishing modules; a
substrate cleaner having an orientation parallel to the first
orientation of the polishing modules; a first robot positioned
between the substrate cleaner and polishing modules, the first
robot laterally positionable in a direction parallel to the first
orientation of the polishing modules and adapted to selectively
position a substrate adjacent each of the plurality of polishing
modules; four load cups aligned parallel to the first orientation
of the polishing modules, and adapted to transfer substrates
between the polishing heads and the first robot; factory interface
adapted to accept a plurality of substrate storage cassettes; and a
second robot disposed in the factory interface and adapted to
transfer substrates between the cassettes and the first robot.
10. The polishing system of claim 9 further comprising a rail
disposed between the substrate cleaner and the plurality of
polishing modules, wherein the first robot is slidably coupled to
the rail and adapted to be selectively positioned along the
rail.
11. The polishing system of claim 10 further comprising a third
robot slidably coupled to the rail.
12. The polishing system of claim 9 further comprising: a third
robot disposed at an end of the substrate cleaner opposite the
factory interface.
13. A method of polishing a substrate, comprising: moving a
substrate, retained in a transfer device, in a first direction to
position the substrate proximate a first load cup selected from a
plurality of load cups aligned parallel to the first direction;
moving the substrate in a second direction perpendicular to the
first direction to a first polishing module; polishing the
substrate in the first polishing module; moving the substrate in a
third direction that is opposite the second direction to the
transfer device; moving the substrate retained in the transfer
device to position the substrate proximate a second load cup
selected from the plurality of load cups; moving the substrate in
the second direction to a second polishing module; and polishing
the substrate in the second polishing module.
14. The method of claim 13 further comprising: moving the substrate
in the third direction to the transfer device; and moving the
substrate in the third direction to a cleaning module.
15. The method of claim 14 further comprising: moving a substrate
through the cleaning module in a fourth direction that is opposite
the first direction.
16. The method of claim 13 further comprising: polishing a second
substrate in the second polishing module; polishing a third
substrate in a third polishing module; and polishing a fourth
substrate in a fourth polishing module, wherein the second, third
and fourth substrates are polished while the first substrate is
polished in the first polishing module.
17. The method of claim 13, wherein the step of moving the
substrate proximate the second load cup further comprises moving
the transfer device in the first direction.
18. The method of claim 13, wherein the step of moving the
substrate proximate the second load cup further comprises moving
the transfer device in a third direction that is opposite the first
direction.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims the benefit of prior, co-pending
U.S. patent application Ser. No. 09/796,303, filed Feb. 27, 2001
which claims benefit of U.S. Provisional Application No.
60/185,812, filed Feb. 29, 2000, which are herein incorporated by
reference in their entirety.
BACKGROUND OF THE DISCLOSURE
[0002] 1. Field of Invention
[0003] The present invention relates generally to a system and
method for planarization of a workpiece such as a semiconductor
substrate or wafer.
[0004] 2. Background of Invention
[0005] In semiconductor wafer processing, the use of chemical
mechanical planarization, or CMP, has gained favor due to the
enhanced ability to increase device density on a semiconductor
workpiece, or substrate, such as a wafer. As the demand for
planarization of layers formed on wafers in semiconductor
fabrication increases, the requirement for greater system (i.e.,
tool) throughput with less wafer damage and enhanced wafer
planarization has also increased.
[0006] Two CMP systems that address these issues are described in
U.S. Pat. No. 5,804,507, issued Sep. 8, 1998 to Perlov et al. and
in U.S. Pat. No. 5,738,574, issued Apr. 15, 1998 to Tolles et al.,
both of which are hereby incorporated by reference in their
entirety. Perlov et al. and Tolles et al. disclose a CMP system
having a planarization apparatus that is supplied wafers from
cassettes located in an adjacent liquid filled bath. A transfer
mechanism, or robot, facilitates the transfer of the wafers from
the bath to a transfer station. From the transfer station, the
wafers are loaded to one of four processing heads mounted to a
carousel. The carousel moves the processing heads and wafers to
various planarization stations where the wafers are planarized by
moving the wafer relative to a polishing pad in the presence of a
slurry or other fluid medium. The polishing pad may include an
abrasive surface. Additionally, the slurry may contain both
chemicals and abrasives that aid in the removal of material from
the wafer. After completion of the planarization process, the wafer
is returned back through the transfer station to the proper
cassette located in the bath.
[0007] Another system is disclosed in U.S. Pat. No. 5,908,530,
issued Jun. 1, 1999 to Hoshizaki et al., which is hereby
incorporated by reference in its entirety. Hoshizaki et al. teaches
an apparatus for planarizing wafers wherein the wafer is subjected
to uniform velocity across the wafer surface with respect to the
abrasive surface. The uniform velocity across the wafer surface
coupled with a multi-programmable planarization pattern results in
a uniform rate of material removal from the wafer surface. In
addition, Hoshizaki et al. provides a number of optional routines
that allow a user to fine tune material removal from the wafer.
[0008] Another system is disclosed in U.S. patent application Ser.
No. 09/556,495, filed Apr. 21, 2000 to Sommer (hereinafter referred
to as "Sommer '495") which is hereby incorporated by reference in
its entirety. Sommer '495 describes a planarization system
comprising two polishing heads for retaining wafers coupled to a
drive system disposed over a single web. By polishing two wafers
simultaneously on a single web, the rate of wafer throughput is
enhanced.
[0009] The systems described above can generally utilize polishing
pads with and without abrasive finishes. The polishing pads may be
stationary or move relative to the wafer, e.g., rotationally or
linearly. Additionally, abrasive slurry, de-ionized water and other
fluids may be delivered to the polishing pad during processing.
[0010] Common to these and other systems is the need to reduce the
cost of ownership and to increase the wafer throughput. Both of
these attributes are highly desirably and necessary to remain
competitive in the semiconductor marketplace. The cost of ownership
can be effectively reduced by providing a system having a compact
footprint. Small system footprints allow for a greater number of
systems in a facility production area, thus decreasing the system
cost per unit factory area while contributing to an increase in
factory capacity by freeing floor space for other processing and
support systems. Additionally, increased throughput both
contributes to reducing the cost of ownership while reducing
manufacturing costs associated with production/machine time.
Increased throughput also decreases the cost per processed wafer
that allows for greater profitability and increased latitude on
product pricing, factors that greatly enhance the manufacturer's
market position relative to his competitors.
[0011] Therefore, there is a need for a chemical mechanical wafer
planarization system that provides increased wafer throughput while
minimizing the footprint of the system.
SUMMARY OF INVENTION
[0012] One aspect of the present invention provides a chemical
mechanical planarization system for planarizing wafers including a
wafer transfer corridor. In an exemplary embodiment, the system
includes a transfer corridor, at least one corridor robot, one or
more polishing modules and at least one loading device. The
corridor robot is disposed in the transfer corridor and is
positionable between a first end and a second end of the transfer
corridor. The one or more polishing modules each include one or
more polishing heads for holding workpieces during processing. The
polishing modules are disposed adjacent the transfer corridor. The
loading device is disposed between the transfer corridor and the
polishing modules and is adapted to transfer workpieces
therebetween. Generally, the loading device includes at least one
load cup.
[0013] In another embodiment of the invention, the planarization
system additionally comprises a first robot, a second robot, one or
more workpiece (e.g., wafer) storage cassettes, and a cleaning
module. The first robot is adapted to transfer the workpiece
between the storage cassettes, the cleaning module and the first
staging area. The second robot is adapted to transfer the workpiece
between the second staging area and the cleaning module.
[0014] In another aspect of the invention, a method of processing a
workpiece is disclosed. In an exemplary embodiment, the method
generally comprises the steps of gripping one or more workpieces
from a first staging area by a first robot, transferring the one or
more workpieces gripped by the first robot to one or more load
cups, transferring the one or more workpieces in the load cups into
respective polishing heads of a first chemical mechanical polishing
module, processing the one or more workpieces, transferring the one
or more workpieces from the respective polishing heads into the one
or more load cups, gripping one or more workpieces from the one or
more load cups by the first robot, and, transferring the one or
more workpieces gripped by the first robot to a second staging
area. In another embodiment, the method additionally comprises the
steps of simultaneously processing a second set of one or more
workpieces in a second polishing module in a loading sequence
similar to the first.
BRIEF DESCRIPTION OF DRAWINGS
[0015] The teachings of the present invention can be readily
understood by considering the following detailed description in
conjunction with the accompanying drawings, in which:
[0016] FIG. 1 is a schematic plan view of a chemical mechanical
planarization system of the present invention;
[0017] FIG. 2 depicts an elevation of a transfer robot;
[0018] FIG. 3 depicts a staging platform;
[0019] FIG. 4 is a side elevation of a corridor robot;
[0020] FIG. 5 is a plan view of the corridor robot taken along
section line 5--5 of FIG. 4;
[0021] FIG. 6 is an elevation depicting the transfer of workpieces
between the corridor robot and the staging platform;
[0022] FIG. 7 is an elevation of a shuttle table;
[0023] FIG. 8 is an exploded view of the shuttle table of FIG.
7;
[0024] FIG. 9 is an elevation of a polishing module;
[0025] FIG. 10 is a perspective view of a drive system; and,
[0026] FIG. 11 is an elevation of the drive system of FIG. 10.
[0027] To facilitate understanding, identical reference numerals
have been used, where possible, to designate identical elements
that are common to the figures.
DETAIL DESCRIPTION OF INVENTION
[0028] FIG. 1 depicts a schematic view of a chemical mechanical
planarization system 100 that generally includes a factory
interface 101, one or more polishing modules 106 (illustratively
shown as a first polishing module 106A and a second polishing
module 106B) and a wafer transfer corridor 104. Generally, the
wafer transfer corridor 104 is disposed between the polishing
modules 106 and the factory interface 101 to facilitate wafer
transfer therebetween. The embodiment of the system 100 shown in
FIG. 1 is configured to process two wafers at a time on each
polishing module 106. However, the system 100 may alternatively be
configured to process single wafers or more than two wafers on each
polishing module 106.
[0029] The factory interface 101 generally comprises one or more
wafer storage cassettes 102, a first transfer robot 110, a second
transfer robot 154 and a cleaning module 108. The cleaning module
108 is typically disposed between the first transfer robot 110 and
the second transfer robot 154. The first transfer robot 110 is
disposed in an enclosure 114 proximate the cleaning module 108. The
enclosure 114 has at least a first port 116, a second port 118 and
a third port 120. The first port 116 is adapted to accept the one
or more wafer cassettes 102. The second port 118 is typically
disposed opposite the first port 116 and defines the exit of the
cleaning module 108. The third port 120 is typically disposed
between the first port 116 and the second port 118. The third port
120 provides access to a first end 122 of the wafer transfer
corridor 104. The enclosure 114 may additionally comprise a Class
10,000 environment within the enclosure 114 to minimize particulate
contamination during wafer transfer. Such an environment may be
provided utilizing HEPA air filters such as those available from
Camfil-Farr Corporation, of Riverdale, N.J.
[0030] The first transfer robot 110 is configured to transfer
workpieces or wafers 126 between the exit of the cleaning module
108, the one or more wafer storage cassettes 102 and the first end
122 of the wafer transfer corridor 104. The second transfer robot
154 is configured to handle wafers in a "wet" condition after
polishing and is generally configured similarly to the first
transfer robot 110. One skilled in the art will recognize that
other types of wafer transfer robots having a suitable range of
motion may be alternatively utilized.
[0031] FIG. 2 depicts one embodiment of the first transfer robot
110. The first transfer robot 110 is generally a multi-link, single
blade robot having a range of motion suitable to transfer the wafer
126 between the cleaning module 108, the storage cassettes 102 and
the wafer transfer corridor 104. In one embodiment, the first
transfer robot 110 includes a first arm 202 having a proximate end
204 coupled to a cylinder 206 that can be actuated through a
vertical range of motion from a base 208 of the first transfer
robot 110. A second arm 210 has a proximate end 212 coupled to a
distal end 214 of the first arm 202. A vacuum blade 216 is coupled
to the distal end 218 of the second arm 210. Typically, the vacuum
blade 216 is coupled to the second arm 210 via a rotary actuator
220 so that the wafer 126 may be orientated "feature-side down" for
processing. The vacuum blade 216 provides a gripping means for
securing the wafer 126 to the first transfer robot 110 during wafer
transfer. Optionally, other types of gripping means may be
utilized, such as edge clamps, electrostatic chucks and the like.
The second transfer robot 154 is similarly configured.
[0032] Referring back to FIG. 1, the second transfer robot 154 is
positioned to transfer wafers 126 between a second end 124 of the
wafer transfer corridor 104 and an entrance 172 of the cleaning
module 108. The second transfer robot 154 is configured to load
wafers from the wafer transfer corridor 104 into the cleaning
module 108. Optionally, a metrology device 103, such as available
from Nova Measuring Instruments, Ltd., of Phoenix, Ariz., may be
disposed adjacent the second transfer robot 154 to provide
information regarding layer thickness or other processing metric
such as defect scanning.
[0033] The cleaning module 108 generally comprises an enclosure 174
having the entrance port 172 proximate the second transfer robot
154 and the exit port defined by the second port 118 of the
enclosure 114. The cleaning module 108 may comprise any number or
combination of known processes utilized for cleaning residual
slurry, contamination and other polishing residues from the
surfaces of the polished wafer. Generally, the cleaning module 108
includes a conveyor (not shown) that receives processed wafers from
the second transfer robot 154. The conveyor transports the wafers
126 through one or more cleaning zones 171 where the wafer is
cleaned by spraying the wafers with a cleaning fluid or de-ionized
water, scrubbing the wafers using brushes 173, and/or by using
ultra and megasonic energy. The wafers can be cleaned either in a
horizontal or vertical position. Those wafers cleaned vertically
benefit from the assistance of gravity in removing the slurry and
other contaminants from the wafer. Once the wafer has been cleaned
it can be introduced into a spin-rinse-dry device 175 where the
wafer can be rinsed and dried. The wafer is then positioned
adjacent the second port 118 where the cleaned wafer is removed
from the cleaning module by the first transfer robot 110 and
returned to one of the wafer cassettes 102. One cleaning module
that can be used to advantage in the invention is a MESA.TM. wafer
cleaner available from Applied Materials, Inc., located in Santa
Clara, Calif.
[0034] The wafer transfer corridor 104 is generally positioned
between the factory interface 101 and the polishing modules 106.
The wafer transfer corridor 104 generally comprises at least one
corridor robot and at least one loading device. The corridor robot
generally moves wafers between staging areas disposed between the
first end 122 and the second end 124 of the wafer transfer corridor
104. Typically, each staging area includes one or more staging
platforms that facilitate queuing and transferring of wafers
between the corridor robot and the wafer transfer robots 110, 154.
The loading device generally transfers the wafers between the
corridor robot and the polishing module 106.
[0035] In one embodiment, the wafer transfer corridor 104 comprises
a first corridor robot 138, a second corridor robot 140 and at
least one loading device 112. The corridor transfer robots 138, 140
travel between the first end 122 and the second end 124 of the
wafer transfer corridor 104. The wafer transfer corridor 104
includes a first staging area 128, a second staging area 136 and a
third staging area 134 that is disposed between the first and
second staging areas 128, 136. Typically, one loading device 112 is
disposed between each staging area 128, 136, 134 and the polishing
modules 106. Alternatively, the system 100 may utilize one or more
loading devices 112 positioned remotely from the transfer corridor
104.
[0036] The first staging area 128 is disposed at the first end 122
of the wafer transfer corridor 104 adjacent the third port 120. In
one embodiment, the first staging area 128 includes a first staging
platform 130 and a second staging platform 132 disposed therein.
The platforms 130, 132 allow both the first transfer robot 110 and
the first corridor robot 138 to access wafers disposed thereon.
[0037] The third staging area 134 is disposed between the first and
second staging areas 128, 136. In one embodiment, the third staging
area 134 includes a third staging platform 150 and a fourth staging
platform 152 disposed therein. The platforms 150, 152 allow both
the first corridor robot 138 and the second corridor robot 140 to
access wafers disposed thereon.
[0038] The second staging area 136 is disposed at the second end
124 of the wafer transfer corridor 104 adjacent a port 170 that
allows the second transfer robot 154 access to the staging area
136. In one embodiment, the second staging area 136 includes a
fifth staging platform 156 and a sixth staging platform 158
disposed therein. The platforms 156, 158 allow both the second
transfer robot 154 and the second corridor robot 140 to access
wafers disposed thereon.
[0039] FIG. 3 depicts a perspective view of the first staging
platform 130. Illustrative of other staging platforms, the first
staging platform 130 comprises a circular base 302 that has a
raised peripheral rim 304. The raised rim 304 prevents a wafer (not
shown) that is set on the base 302 from sliding off. The first
staging platform 130 is additionally coupled to an actuator 306
that provides vertical movement to the base 302. Optionally, the
first staging platform 130 further comprises one or more fluid
nozzles 308 that maintain the wafer in a "wet" condition by bathing
the wafer with a fluid such as de-ionized water. Alternatively, the
one or more nozzles 308 may be remotely located form the first
staging platform 130 or additionally in other locations throughout
the system 100 to prevent drying of contaminants (i.e., slurry
and/or other materials) on the wafer's surface.
[0040] The first staging platform 130 has cut-outs 310 in the
raised rim 304 that extend at least partially into the base 304.
The cut-outs 310 permit the wafer to be set on and removed from the
base 302 of the staging platform by the corridor robots 112 without
interfering with the gripping mechanism of the corridor robots
112.
[0041] Each staging platform of the first and the second staging
areas 128, 136 has a slot 312 in the raised rim 304 that extend at
least partially into base 302. The cut-out 312 allows the wand 216
of the transfer robots 110, 154 to set and retrieve the wafer from
the base 302 of the staging platforms 130, 132 156, 158.
[0042] FIGS. 4 and 5 depict a side elevation and a bottom plan view
of the first corridor robot 138. The reader is encouraged to
simultaneously refer to FIGS. 1, 4 and 5 to best understand the
first corridor robot 138. The first corridor robot 138 generally
includes at least one edge gripper 408 coupled to a guide 404 that
moves along a rail 406. Typically, the first corridor robot 138 is
configured with the same number of grippers as staging platforms
present in the respective area serviced by the robot. An actuator
402, generally a linear motion device moves the first corridor
robot 138 along the rail 406. The actuator 402 may comprise a
linear motion devices such as a pneumatic cylinder, hydraulic
cylinder, ball screw, servo/stepper motor coupled with belt drives
or the like able to position the first corridor robot 138 along the
rail 406. The second corridor robot 140 may be driven independently
from the first corridor robot 138 by a separate actuator (not
shown). Optionally, the movement of the corridor robots 138, 140
may be linked. The actuator 402, rail 406 and guide 404 are
configured to provide a range of motion such that the edge gripper
408 may access at least two staging areas (e.g., the first staging
area 130 and the third staging area 134).
[0043] In the illustrative embodiment, the first corridor robot 138
comprises at least a first gripper 142 and a second gripper 146.
The first corridor robot 138 has a range of motion that allows the
wafers 126 in the first and second staging platforms 130, 132 to
the transferred to a third staging platform 150 and a fourth
staging platform 152 of the third staging area 134. Similarly, the
second corridor robot 140 has a range of motion that allows the
wafers in the third and a fourth staging platforms 150, 152 to be
transferred to a fifth staging platform 156 and a sixth staging
platform 158 of the second staging area 136.
[0044] Each gripper 142, 146 generally comprises a first member 502
and an opposing second member 504 as shown in FIG. 5. The first and
second member 502, 504 can be actuated to move towards each other.
The first member 502 includes a first post 506 and a second post
508 extending perpendicularly therefrom in a spaced-apart relation.
The second member 504 includes a third post 510 and a fourth post
512 extending perpendicularly therefrom in a spaced-apart relation.
Each post (506, 508, 510 and 512) contains a co-planar notch 410
slightly greater in width than the thickness of the wafer. The
first member 502 and the second member 504 are normally in a
position such that the posts 506, 508, 510 and 512 are positioned
outside of the circumference of the wafer. When the first gripper
142 is actuated, the first member 502 moves closer to the second
member 504, closing the first gripper 142. As the first gripper 142
closes, the notches 410 of the respective posts retain the wafer
126 by its perimeter (i.e., edge contact). The second corridor
robot 140 is typically configured similarly to the first corridor
robot 138.
[0045] Referring back to FIG. 1, the first transfer robot 110
typically retrieves an unprocessed wafer 126 from one of the wafer
cassettes 102 and places the wafer on either platform 130, 132
residing in first staging area 128. After loading one of the
platforms 130, 132, the first transfer robot 110 may retrieve a
cleaned, processed wafer exiting the cleaning module 108 and return
the cleaned wafer to the wafer cassettes 102 or the robot 110 may
retrieve and load another unprocessed wafer on the remaining
platform in the first staging area 128.
[0046] The wafer transfer corridor 104 is generally positioned
between the factory interface 101 and the polishing modules 106.
The wafer transfer corridor 104 is orientated such that wafers
being transferred along the transfer corridor 104 may be loaded
into any of the polishing modules 106. In one embodiment, wafers
126 are transferred between the first staging area 128 and the
third staging area 134 via a first corridor robot 138, while wafers
126 are transferred between the third staging area 134 and the
second staging area 136 by a second corridor robot 140.
[0047] Referring to FIG. 6, transfer of wafers from the first
staging platform 130 to the first corridor robot 138 is
accomplished by first positioning the first gripper 142 and second
gripper 146 above the second staging platform 132 and first staging
platform 130, respectively, that are in a lowered position (the
second staging platform 132 is shown in a raised position to
illustrate securing of the wafer 126 by the first gripper 142). As
illustrated by the first gripper 142, second staging platform 132
is raised to align the wafer 126 disposed on the base 302 in a
co-planar position with the notches 410 of the posts of the first
gripper 142. The first member 502 and the second member 504 are
actuated to secure the wafer 126 in the notches 410. The second
staging platform 132 is then lowered to allow the posts of the
first gripper 142 to clear the raised rim 304 of the second staging
platform 132, allowing the first corridor robot 138 to move away
from the first staging area 128. In practice, the first and second
staging platforms 130, 132 typically move in unison allowing both
of the wafers in the first staging area 128 to be transferred
simultaneously thus increasing system throughput. Wafers are loaded
onto the staging platforms from the grippers in the reverse manner.
The other corridor robots interface similarly with the other
staging platforms.
[0048] Returning to FIG. 1, the one or more loading devices 112 are
generally positioned between adjoining staging areas to transfer
wafers to and from the polishing modules 106. Alternately, one
loading device 112 may service the entire transfer corridor 104.
Typically, the loading devices 112 include a positioning mechanism
(described below with reference to FIGS. 7 and 8) and one or more
load cups 166. The positioning mechanism transfers the one or more
load cups 166 between a first position and a second position. In
the first position, wafers may be loaded and unloaded from the load
cups 166 by one of the corridor robots 138, 140. In the second
position, the load cups 166 may transfer the wafers to and from the
polishing heads 164 of the polishing modules 106.
[0049] In one embodiment, each loading device 112 includes a
shuttle table. A first shuttle table 160 is positioned between the
first staging area 128 and the third staging area 134, and a second
shuttle table 162 is positioned between the third staging area 134
and the second staging area 136.
[0050] FIGS. 7 and 8 are a side elevation and an exploded
perspective view of the first shuttle table 160. The reader should
note the illustrated first shuttle table 160 depicts an exemplary
device for transferring wafers between the transfer corridor 104
and the processing modules 106. The first shuttle table 160 may
alternatively comprise other devices capable of transferring wafers
between a plurality of processing modules while having the
positional accuracy to enable transfer of the wafer into a
polishing head.
[0051] The illustrative first shuttle table 160 comprises a yoke
802, support members 804, and load cups 166 that include a first
load cup 806 and a second load cup 808. The load cups 806, 808 are
disposed in the yoke 802, and protrude through a yoke cover 810
fastened to the yoke 802. The support members 804 are coupled to
the yoke 802 at one end and are coupled to one or more positioning
mechanisms 702 at the other end. The positioning mechanisms 702
permit the load cups 806, 808 to be moved between the transfer
corridor 104 and the first polishing module 106A. Generally, the
movement of the first shuttle table 160 is typically perpendicular
to the movement of the corridor robots 138, 140. The positioning
mechanism 702 may comprise any number of linear motion devices,
including pneumatic cylinders, hydraulic cylinders, ball screws,
servo/stepper motors coupled with belt drives and the like. The
support member 804 is of sufficient strength to maintain the load
cups 806, 808 in a substantially parallel relation to the polishing
heads 164 of the first polishing module 106A during wafer transfer
therebetween. The second shuttle table 162 is similarly
configured.
[0052] The load cups 166 may comprise any number of devices known
in the art suitable for positioning the wafer 126 into a polishing
head 164. Examples of such load cups are disclosed in the
previously incorporated U.S. patent application Ser. No. 09/718,522
and U.S. patent application Ser. No. 09/414,907, filed Oct. 8, 1999
by Tobin, which is hereby incorporated by reference in it
entirety.
[0053] Alternatively, one or more loading devices 112 may be
positioned adjacent the wafer transfer corridor 104 such that the
loading device 112 may transfer wafers between the wafer transfer
corridor 104 and one or more load cups 166 positioned on or
proximate to a respective polishing modules 106. The load cups 166
are positioned on the polishing module 106 such that wafers within
the load cup 166 may be loaded into the polishing heads 164 of the
polishing module 106 without damage.
[0054] Generally, the loading devices 112 are positioned in a first
position proximate the transfer corridor 104 when wafers are to be
transferred to or from the corridor robots 138, 140. In an example
of a transfer sequence, the corridor robots 138, 140 generally
position the wafers held therein concentric to the loading device
112 that is positioned proximate the transfer corridor 104. The
load cups 806, 808 are then actuated to rise to a height wherein
the wafers are substantially disposed in the load cups. The
grippers 142, 146 then release the wafers into the load cups 806,
808. The load cups 806, 808 are lowered to clear the grippers 142,
146 and the loading device is actuated to move away from the
transfer corridor 104 and into a position where the wafers may be
transferred to the polishing module 106.
[0055] Referring back to FIG. 1, the plurality of polishing modules
106 are positioned proximate the wafer transfer corridor 104 so
that wafers 126 may be loaded into the polishing modules 106 from
the wafer transfer corridor 104 by one or more loading devices 112.
The plurality of polishing modules 106, shown as the first
polishing module 106A and 106B, are respectively disposed adjacent
to the first shuttle table 160 and the second shuttle table 162 of
the wafer transfer corridor 104. Each polishing module 106A, 106B
is positioned to receive and return wafers to the wafer transfer
corridor 104 from a respective loading device 112. The polishing
modules 106A, 106B may comprise buffing, polishing, rinsing,
cleaning and/or other processes associated with planarizing a
workpiece. The polishing modules 106A, 106B may provide either a
linear polishing motion or a rotational polishing motion to the
wafer relative a polishing surface 168 of the polishing modules
106A, 106B.
[0056] FIG. 9 depicts a simplified elevation of one embodiment of
the first polishing module 106A including a polishing media
magazine 902, a polishing table 904, and a drive system 906. The
second polishing module 106B can be similarly configured.
[0057] The polishing media magazine 902 generally comprises an
unwind 908 and a winder 910. A web 912 of polishing media is run
between the unwind 908 and the winder 910. The web 912 can be
substantially "rolled-up" at either the unwind 908 and the winder
910, or partially wound on both the unwind 908 and the winder 910
such that various portions of the web 912 may be selectively
exposed upon the polishing table 904, thus defining the polishing
surface 168. The web 912 may be indexed or advanced, between or
during wafer processing.
[0058] The web 912 of polishing media is generally comprised of a
thin polymeric film having a working surface 914 comprising either
a polishing pad or fixed abrasive covering at least a portion of
the width of the web 912. The web 912 of polishing media may be
substantially impermeable to the polishing fluid (i.e., a slurry,
deionized water or other fluid media that assists in polishing).
The working surface 914 may optionally comprise an abrasive
coating, finish, covering, texture or combination thereof.
[0059] The polishing table 904 supports the web 912 during
processing when the polishing head 164 and the wafer 126 are
disposed against the working surface of the web 912. At least one
nozzle 916 is disposed on the polishing table 904 adjacent each web
912 to introduce a polishing fluid or other fluid to the working
surface 914 of the web 912 during wafer processing. Generally, the
polishing fluid provides chemical activity that assists in the
polishing process. The polishing fluid is typically selected
dependant on the material being polished and may contain an
abrasive component. Optionally, the working surface 914 may
comprise an abrasive coating, finish, covering and/or texture. An
example of such a polishing media magazine 902 is described in U.S.
patent application Ser. No. 08/833,278, filed Apr. 4, 1997 by
Donohue et al., which is hereby incorporated by reference in its
entirety.
[0060] The polishing media magazine 902 may further comprise one or
more conditioning devices 918 that may be actuated to contact and
condition the working surface 914 of the web 912. Generally, the
conditioning device 918 comprises two rollers driving in opposing
directions that are selectively actuated against with the working
surface 914 of the web 912 to condition the working surface 914.
The conditioning device 918 conditions (i.e., dresses) the working
surface 914 of the web 912 to create a uniformly textured surface
that removes material from the surface of the wafer at a uniform
rate. Other types of conditioning devices 918 may optionally be
utilized alone or in conjunction with the rollers. Examples of such
devices are described in U.S. patent application Ser. No.
09/651,659, filed Aug. 29, 2000 by Sommer et al., which is hereby
incorporated by reference in its entirety.
[0061] FIGS. 10 and 11 are a perspective view and an elevation of
one embodiment of the system 100 illustrating the drive system 906
found on each polishing module 106A, 106B. The drive system 906 is
coupled to the polishing table 904. The drive system 906 typically
comprises a first linear motion device 1002, a second linear motion
device 1004 and one or more polishing heads 164. The polishing head
164 is movably positioned above the working region 168 of the web
912. The first linear motion device 1002 and the second linear
motion device 1004 (which could be replaced by one device providing
at least an equivalent range of motion) couples the polishing head
164 to the polishing table 904. The linear motion devices 1002,
1004 move the polishing head 164 in programmable pattern in
relation to the polishing table 904. Optionally, more than one
polishing head 164 may be positioned on each drive system 906.
[0062] The first linear motion device 1002 generally comprises a
stage 1006, a roller bearing guide 1008 and a driver 1010. The
stage 1006 is fabricated from aluminum or other light weight
material. The stage 1006 may comprise stiffening ribs to minimize
the deflection in a direction normal to the polishing table 904.
The use of light weight materials minimizes the inertia of the
stage 1006 that effects stage motion. The guide 1008 is coupled to
the stage 1006 and interfaces with a rail 1012 disposed on a
support 1014 fixed to the polishing table 904. The guide 1008
allows the stage 1006 to move along the support 1014 in a linear
motion generally parallel to the length of the webs 912. The guide
1008 may alternatively comprise solid bearings, air bearings or
similar devices. The driver 1010 provides motion to the stage 1006
relative the polishing table 904. The driver 1010 may comprise
"Sawyer" motors, ball screws, cylinders, belts, rack and pinion
gears, servo motors, stepper motors and other devices for creating
and controlling linear motion. Generally, one portion of the driver
1010 is connected to the support 1014 while a second portion is
connected to the stage 1006.
[0063] The second linear motion device 1004 generally comprises a
carrier 1016, a roller bearing guide 1018 and a driver 1020. The
carrier 1016 is also fabricated from aluminum or other light weight
material. The guide 1018 is coupled to the carrier 1016 and
interfaces with a rail 1022 disposed on stage 1006. The guide 1018
allows the carrier 1016 to move along the stage 1006 in a linear
motion substantially perpendicular to the motion of the stage 1006.
The guide 1018 may alternatively comprise solid bearings, air
bearings or similar bearing devices. The driver 1020 provides
motion to the carrier 1016 relative the stage 1006. The driver 1020
may comprise "Sawyer" motors, ball screws, cylinders, belts, rack
and pinion gears, servo motors, stepper motors and other devices
for creating and controlling linear motion.
[0064] The one or more polishing heads 164 are disposed on the
carrier 1016. In one embodiment, the polishing head 164 is a
DIAMOND HEAD.TM. wafer carrier 1016, available from Applied
Materials, Inc., Santa Clara, Calif. The one or more polishing
heads 164 are coupled to the carrier 1016 in a position such that
the polishing head 164 is disposed above the web 912. Each
polishing head 164 is coupled to the carrier 1016 via one or more
actuators 1024 that provides motion to the polishing heads 164 in a
direction normal to the working surface 914 of the web 912. The
range of motion of the polishing head 164 allows a wafer 126
disposed in the polishing head 164 to contact the working surface
168 of the web 912. An example of a drive system that may be
modified to benefit from the invention is described in U.S. patent
application Ser. No. 08/961,602, filed Oct. 31, 1997 by Sommer,
which is hereby incorporated by reference in its entirety.
[0065] Referring back to FIG. 1, wafers 126 returning to the wafer
transfer corridor 104 from the first polishing module 106A are
either processed in the polishing module 106B or transported to the
second staging area 136 where the wafers are set on the fifth and
sixth staging platforms 156, 158. From the fifth and sixth staging
platforms 156, 158, the second transfer robot 154 retrieves the
wafers (from one platform, then the other) through a port 170 at
the second end 124 of the wafer transfer corridor 104. The wafers
are then loaded through the entrance port 172 into the cleaning
module 108.
[0066] Once the wafer has been cleaned, rinsed and dried, the wafer
is then positioned adjacent the second port 118 where the cleaned
wafer is removed from the cleaning module 108 by the first transfer
robot 110 and returned to one of the one or more wafer cassettes
102.
[0067] The relative position of multiple polishing modules 106
along the transfer corridor 104 in concert with the utilization of
the cleaning module 108 as a return path to the wafer cassettes 102
provides a compact system 100 footprint that allows for multiple
wafer processing. Moreover, the system 100 may be configured with
additional polishing modules 106 with minimal additional
consumption of floor space.
[0068] Referring primarily to FIG. 1, an illustrative processing
sequence is described demonstrating one possible processing
sequence. One skilled in the art will recognize that other
processing sequences are envisioned and readily accommodated. In
operation, a first unpolished wafer is removed from one of the
wafer cassettes 102 by the first transfer robot 110, flipped and
placed on either the first or second staging platform 130, 132 in
the first staging area 128. Typically, the first transfer robot 110
then retrieves a second unpolished wafer to fill the other staging
platform so that both the first and the second staging platforms
130, 132 contain unpolished wafers.
[0069] The first corridor robot 138 moves over the first staging
area 128, aligning the grippers 142, 146 concentrically above the
wafers disposed in the staging platforms 130, 132. The first
staging platform 130 and the second staging platform 132 are
actuated, elevating the wafers residing on the base 302 of the
staging platforms to a position co-planar with the notches 410 of
the posts extending from the grippers 142, 146. The grippers 142,
146 are then actuated to grasp the perimeter of the wafers in the
notches 410 of the gripper 142, 146. The staging platforms 130, 132
are subsequently lowered to permit the grippers 142, 146 securing
the wafers 126 to be transported away from the first staging area
128. Once the wafers are cleared from the first staging area 128, a
second pair of wafers is queued for processing in the first staging
area 128.
[0070] The wafers carried by the first corridor robot 138 are moved
over the first shuttle table 160 and positioned concentrically
above the load cups 166 disposed on the first shuttle table 160.
The load cups 166 are then vertically actuated to a level where the
wafers may be released by the first corridor robot 138 into the
load cups 166 without damage. The wafers are released from the
first corridor robot 138 by de-actuating the grippers 142, 146
(i.e., spreading the first and second members 502, 504 apart). Once
the wafers are in the load cups 166, the load cups 166 are
retracted, allowing the first shuttle table 160 to move free of the
first corridor robot 138.
[0071] The first shuttle table 160 containing the wafers in the
load cups 166 are moved from the wafer transfer corridor 104 to a
position proximate the first polishing module 106A. The drive
system 906 of the first polishing module 106A positions the
polishing heads 164 concentrically above the load cups 166. The
load cups 166 are actuated to load the wafers into the polishing
heads 164. The drive system 906 then moves the wafers over the
polishing web 912. The wafers are brought into contact with the
polishing web 912 in the presence of the polishing fluid, and moved
in a predetermined polishing pattern, polishing the wafers surface
against the polishing web 912.
[0072] After polishing is complete, the wafers are returned to the
load cups 166 of the first shuttle table 160. The first shuttle
table 160 then returns the processed wafers to the wafer transfer
corridor 104 wherein the wafers are again retained by the grippers
142, 146 of the first corridor robot 138.
[0073] The processed wafers are transferred by the first corridor
robot 138 to the third staging area 134. Once the wafers in the
grippers 142, 146 of the first corridor robot 138 are
concentrically aligned with the third and the fourth staging
platforms 150, 152, the third and the fourth staging platforms 150,
152 are vertically actuated to place the base 302 of the staging
platforms 150, 152 proximate the wafers. The grippers 142, 146 are
de-actuated and the wafers are positioned on the third and fourth
staging platforms 150, 152. The staging platforms 150, 152 are then
lowered to permit the first corridor robot 138 to exit the third
staging area 134 and retrieve the queued set of wafers from the
first staging area 128 for processing in the first polishing module
106A. The wafers in the third staging area 134 are queued for
polishing in the second polishing module 106B.
[0074] The second corridor robot 140 retrieves the wafers processed
in the first polishing module 106A from the third staging area 134
in a manner similar to the sequence described above for the first
corridor robot 138. The second corridor robot 140 moves the wafers
to the second staging area 136 if no further polishing is required,
or to a position where the wafers may be loaded in to the second
shuttle table 162. If the wafers are to be polished by the second
polishing module 106B, the wafers are transferred by the second
shuttle table 162 to the second polishing module 106B wherein the
wafers are polished and returned back to the second corridor robot
140 similar to the sequence as described above with reference to
the first polishing module 106A.
[0075] The queuing of wafer pairs awaiting polishing minimizes the
dwell time between polishing. Additionally, the second polishing
module 106B may polish a wafer pair as the first polishing module
106A polishes another wafer pair, thus enhancing wafer throughput.
Optionally, the second corridor robot 140 may retrieve the wafers
from the first shuttle 160 allowing a second set of wafers to be
sequentially loaded into the first shuttle 160 to further minimize
the dwell time of the polishing module 160A.
[0076] The wafers polished by the second polishing module 106B are
transferred by the second corridor robot 140 to the second staging
area 136. At the second staging area 136, the wafers are placed on
the fifth and sixth staging platforms 156, 158. Once in the second
staging area 136, the wafers are sequentially retrieved by the
second transport robot 154. The second transport robot 154 remove
the wafers from the staging platforms 156, 158 and place the wafers
on the conveyor 176 within the cleaning module 108. Optionally, all
or a sample of polished wafers may be loaded by the second robot
154 into the metrology device 103 for data acquisition before
entering the cleaning module 108.
[0077] Once in the cleaning module 108, the wafers 126 are then
transported by the conveyor 176 from the entrance 172 of the
cleaning module 108 to the second port 118 proximate the first
transfer robot 110. While passing through the cleaning module 108,
the wafers are cleaned of debris, residual slurry and other
contamination residing on the wafer's surface.
[0078] When the wafer 126 reaches the exit of the cleaning module
108, the first transfer robot 110 retrieves the wafer from the
cleaning module 108 and returns the wafer to one of the wafer
cassettes 102.
[0079] One skilled in the art will appreciate that the
illustratively described processing sequence is but one possible
variation of a processing sequence that may be performed by the
system 100. For example, the wafers may be routed through the
polishing stations in any sequence, the wafers may be passes
through the cleaning module before, after, or in between polishing
operations, the wafers may be routed through one or more polishing
stations and returned to the cassettes without cleaning, and so
forth.
[0080] Although the teachings of the present invention that have
been shown and described in detail herein, those skilled in the art
can readily devise other varied embodiments that still incorporate
the teachings and do not depart from the spirit of the
invention.
* * * * *