U.S. patent application number 12/124151 was filed with the patent office on 2008-11-27 for methods and apparatus for substrate edge polishing using a polishing arm.
This patent application is currently assigned to APPLIED MATERIALS, INC.. Invention is credited to Paul D. Butterfield, Gary C. Ettinger, Antoine P. Manens.
Application Number | 20080293335 12/124151 |
Document ID | / |
Family ID | 40072854 |
Filed Date | 2008-11-27 |
United States Patent
Application |
20080293335 |
Kind Code |
A1 |
Ettinger; Gary C. ; et
al. |
November 27, 2008 |
METHODS AND APPARATUS FOR SUBSTRATE EDGE POLISHING USING A
POLISHING ARM
Abstract
Apparatus and methods adapted to polish an edge of a substrate
include (1) a polishing tape having a polishing surface and a
second surface and (2) a polishing arm having a longitudinal axis
and adapted to force the polishing surface of the polishing tape
into contact with an edge of a substrate. The polishing arm
includes i) a polishing head adapted to contact the second surface
of the polishing tape, ii) a rocker arm coupled to the polishing
head and adapted to rotate the polishing head around the
longitudinal axis of the polishing arm and iii) a load arm
extending adjacent to the rocker arm and adapted to move the
polishing head in a direction perpendicular to the longitudinal
axis of the polishing arm. Numerous other aspects are provided.
Inventors: |
Ettinger; Gary C.;
(Cupertino, CA) ; Butterfield; Paul D.; (San Jose,
CA) ; Manens; Antoine P.; (Sunnyvale, CA) |
Correspondence
Address: |
DUGAN & DUGAN, PC
245 Saw Mill River Road, Suite 309
Hawthorne
NY
10532
US
|
Assignee: |
APPLIED MATERIALS, INC.
Santa Clara
CA
|
Family ID: |
40072854 |
Appl. No.: |
12/124151 |
Filed: |
May 21, 2008 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60939333 |
May 21, 2007 |
|
|
|
Current U.S.
Class: |
451/41 ; 451/177;
451/296 |
Current CPC
Class: |
B24B 21/004 20130101;
B24B 9/065 20130101; B24B 27/0038 20130101 |
Class at
Publication: |
451/41 ; 451/296;
451/177 |
International
Class: |
B24B 1/00 20060101
B24B001/00 |
Claims
1. An apparatus adapted to polish an edge of a substrate
comprising: a polishing tape having a polishing surface and a
second surface; and a polishing arm having a longitudinal axis and
adapted to force the polishing surface of the polishing tape into
contact with an edge of a substrate, the polishing arm including: a
polishing head adapted to contact the second surface of the
polishing tape; a rocker arm coupled to the polishing head and
adapted to rotate the polishing head around the longitudinal axis
of the polishing arm; and a load arm extending adjacent to the
rocker arm and adapted to move the polishing head in a direction
substantially perpendicular to the longitudinal axis of the
polishing arm.
2. The apparatus of claim 1 wherein the polishing head is adapted
to oscillate as it forces the polishing surface of the polishing
tape into contact with the edge of the substrate.
3. The apparatus of claim 2, wherein the oscillation may be at
least one of continuous and intermittent.
4. The apparatus of claim 1 further comprising a polishing pad
coupled to the polishing head and adapted to contact the second
surface of the polishing tape.
5. The apparatus of claim 4 further comprising a backing block
adapted to couple the polishing pad to the polishing head.
6. The apparatus of claim 1 further comprising a rocker motor
coupled to the rocker arm.
7. The apparatus of claim 6 wherein the rocker motor is adapted to
rotate the rocker arm.
8. The apparatus of claim 1 further comprising an actuator coupled
to the load arm.
9. The apparatus of claim 8, wherein the actuator is adapted to
extend and retract the load arm, such that the polishing surface of
the polishing tape is forced into contact with the edge of the
substrate.
10. The apparatus of claim 9 further comprising a pivot mechanism
adapted to couple the actuator to the load arm.
11. A system adapted to polish an edge of a substrate comprising: a
housing; and one or more edge polishing apparatus, wherein the edge
polishing apparatus comprises: a polishing tape having a polishing
surface and a second surface; and a polishing arm having a
longitudinal axis and adapted to force the polishing surface of the
polishing tape into contact with an edge of a substrate, the
polishing arm including: a polishing head adapted to contact the
second surface of the polishing tape; a rocker arm coupled to the
polishing head and adapted to rotate the polishing head around the
longitudinal axis of the polishing arm; and a load arm extending
adjacent to the rocker arm and adapted to move the polishing head
in a direction substantially perpendicular to the longitudinal axis
of the polishing arm.
12. The system of claim 11 further comprising a central platform
positioned centrally to the one or more edge polishing
apparatus.
13. The system of claim 12 wherein the central platform is adapted
to support the substrate.
14. The system of claim 11 further comprising a controller.
15. The system of claim 14 wherein the controller is adapted to
direct the operation of the system.
16. The system of claim 11 wherein the polishing head is adapted to
oscillate as it forces the polishing surface of the polishing tape
into contact with the edge of the substrate.
17. The system of claim 11 further comprising a rocker motor
coupled to the rocker arm and adapted to rotate the rocker arm.
18. The system of claim 11 further comprising an actuator coupled
to the load arm.
19. The system of claim 18 wherein the actuator is adapted to
extend and retract the load arm, such that the polishing surface of
the polishing tape is forced into contact with the edge of the
substrate.
20. A method for polishing an edge of a substrate comprising:
retracting an actuator in a direction substantially perpendicular
to the longitudinal axis of a polishing arm, and away from a
substrate; moving a pivot mechanism in a counter-clockwise
direction in response to the retraction of the actuator; extending
a load arm forward towards the substrate in response to the
movement of the pivot mechanism; and contacting an edge of the
substrate with a polishing tape in response to the forward movement
of the load arm.
21. The method of claim 20 further comprising contacting the
polishing tape with a backing pad in response to the forward
movement of the load arm such that the polishing tape contacts the
edge of the substrate.
22. The method of claim 21 wherein the backing pad is coupled to a
head portion of the polishing arm.
23. The method of claim 22 further comprising oscillating the
polishing head as it forces the polishing tape into contact with
the edge of the substrate.
24. The method of claim 20 wherein an actuator is coupled to the
load arm and adapted to extend the load arm.
25. The method of claim 20 wherein an actuator is coupled to the
load arm and adapted to retract the load arm.
Description
[0001] The present application claims priority from U.S.
Provisional Patent Application Ser. No. 60/939,333 filed May 21,
2007, entitled "METHODS AND APPARATUS FOR SUBSTRATE EDGE POLISHING
USING A POLISHING ARM" (Attorney Docket No. 11567/L) is hereby
incorporated herein by reference in its entirety for all
purposes.
CROSS-REFERENCE TO RELATED APPLICATIONS
[0002] The present application is related to the following
commonly-assigned, co-pending U.S. patent applications, each of
which is hereby incorporated herein by reference in its entirety
for all purposes:
[0003] U.S. patent application Ser. No. 11/299,295, filed on Dec.
9, 2005 and entitled "METHODS AND APPARATUS FOR PROCESSING A
SUBSTRATE" (Attorney Docket No. 10121);
[0004] U.S. patent application Ser. No. 11/298,555, filed on Dec.
9, 2005 and entitled "METHODS AND APPARATUS FOR PROCESSING A
SUBSTRATE" (Attorney Docket No. 10414);
[0005] U.S. Patent Application Ser. No. 60/939,351, filed May 21,
2007, entitled "METHODS AND APPARATUS FOR POLISHING A NOTCH OF A
SUBSTRATE USING AN INFLATABLE POLISHING WHEEL" (Attorney Docket No.
10674/L);
[0006] U.S. Patent Application Ser. No. 60/939,353, filed May 21,
2007, entitled "METHODS AND APPARATUS FOR FINDING A SUBSTRATE NOTCH
CENTER" (Attorney Docket No. 11244/L);
[0007] U.S. Patent Application Ser. No. 60/939,343, filed May 21,
2007, entitled "METHODS AND APPARATUS TO CONTROL SUBSTRATE BEVEL
AND EDGE POLISHING PROFILES OF EPITAXIAL FILMS" (Attorney Docket
No. 11417/L);
[0008] U.S. Patent Application Ser. No. 60/939,219, filed May 21,
2007, entitled "METHODS AND APPARATUS FOR POLISHING A NOTCH OF A
SUBSTRATE USING A SHAPED BACKING PAD" (Attorney Docket No.
11483/L);
[0009] U.S. Patent Application Ser. No. 60/939,342, filed May 21,
2007, entitled "METHODS AND APPARATUS FOR REMOVAL OF FILMS AND
FLAKES FROM THE EDGE OF BOTH SIDES OF A SUBSTRATE USING BACKING
PADS" (Attorney Docket No. 11564/L);
[0010] U.S. Patent Application Ser. No. 60/939,350, filed May 21,
2007, entitled "METHODS AND APPARATUS FOR USING A BEVEL POLISHING
HEAD WITH AN EFFICIENT TAPE ROUTING ARRANGEMENT" (Attorney Docket
No. 11565/L);
[0011] U.S. Patent Application Ser. No. 60/939,344, filed May 21,
2007, entitled "METHODS AND APPARATUS FOR USING A ROLLING BACKING
PAD FOR SUBSTRATE POLISHING" (Attorney Docket No. 11566/L);
[0012] U.S. Patent Application Ser. No. 60/939,333, filed May 21,
2007, entitled "METHODS AND APPARATUS FOR SUBSTRATE EDGE POLISHING
USING A POLISHING ARM" (Attorney Docket No. 11567/L);
[0013] U.S. Patent Application Ser. No. 60/939,212, filed May 21,
2007, entitled "METHODS AND APPARATUS FOR IDENTIFYING A SUBSTRATE
EDGE PROFILE AND ADJUSTING THE PROCESSING OF THE SUBSTRATE
ACCORDING TO THE IDENTIFIED EDGE PROFILE" (Attorney Docket No.
11695/L);
[0014] U.S. Patent Application Ser. No. 60/939,337, filed May 21,
2007, entitled "METHODS AND APPARATUS FOR HIGH PERFORMANCE
SUBSTRATE BEVEL AND EDGE POLISHING IN SEMICONDUCTOR MANUFACTURE"
(Attorney Docket No. 11809/L);
[0015] U.S. Patent Application Ser. No. 60/939,228, filed May 21,
2007, entitled "METHODS AND APPARATUS FOR POLISHING A NOTCH OF A
SUBSTRATE BY SUBSTRATE VIBRATION" (Attorney Docket No. 11952/L);
and
[0016] U.S. Patent Application Ser. No. 60/939,209, filed May 21,
2007, entitled "METHODS AND APPARATUS FOR CONTROLLING THE SIZE OF
AN EDGE EXCLUSION ZONE OF A SUBSTRATE" (Attorney Docket No.
11987/L).
FIELD OF THE INVENTION
[0017] The present invention relates generally to substrate
processing, and more particularly to methods and apparatus for
polishing an edge of a substrate.
BACKGROUND OF THE INVENTION
[0018] In preparing a substrate for semiconductor device
manufacturing, the edge of the substrate is generally cleaned
and/or polished. Typically, an abrasive tape is applied with some
degree of force to polish bevels on the edge of the substrate. A
fluid may be supplied to assist in the polishing and/or to wash
away dislodged particles. It has proven to be difficult to
consistently control the force applied to the abrasive tape in such
polishing processes. Additionally, the wet environment on the edge
of the substrate due to the supply of fluid may contaminate
portions of the polishing apparatus. Accordingly, improved methods
and apparatus for polishing an edge of a substrate are desired.
SUMMARY OF THE INVENTION
[0019] In a first aspect of the invention, an apparatus adapted to
polish an edge of a substrate is provided. The apparatus includes
(1) a polishing tape having a polishing surface and a second
surface and (2) a polishing arm having a longitudinal axis and
adapted to force the polishing surface of the polishing tape into
contact with an edge of a substrate. The polishing arm includes i)
a polishing head adapted to contact the second surface of the
polishing tape, ii) a rocker arm coupled to the polishing head and
adapted to rotate the polishing head around the longitudinal axis
of the polishing arm and iii) a load arm extending adjacent to the
rocker arm and adapted to move the polishing head in a direction
approximately perpendicular to the longitudinal axis of the
polishing arm.
[0020] In another aspect of the invention, a system adapted to
polish an edge of a substrate is provided. The system includes a
housing; and one or more edge polishing apparatuses. The one or
more apparatuses include (1) a polishing tape having a polishing
surface and a second surface and (2) a polishing arm having a
longitudinal axis and adapted to force the polishing surface of the
polishing tape into contact with an edge of a substrate. The
polishing arm includes i) a polishing head adapted to contact the
second surface of the polishing tape, ii) a rocker arm coupled to
the polishing head and adapted to rotate the polishing head around
the longitudinal axis of the polishing arm and iii) a load arm
extending adjacent to the rocker arm and adapted to move the
polishing head in a direction approximately perpendicular to the
longitudinal axis of the polishing arm.
[0021] In yet another aspect of the invention, a method for
polishing an edge of a substrate is provided. The method includes
retracting an actuator in a direction generally perpendicular to
the longitudinal axis of a polishing arm, and away from a
substrate; rotating a pivot mechanism (e.g., in a counter-clockwise
direction) in response to the retraction of the actuator; extending
a load arm forward towards the substrate in response to the
movement of the pivot mechanism; and contacting an edge of the
substrate with a polishing tape in response to the forward movement
of the load arm.
[0022] Other features and aspects of the present invention will
become more fully apparent from the following detailed description,
the appended claims and the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0023] FIG. 1 is a schematic top view of an exemplary system for
edge polishing according to an embodiment of the present
invention.
[0024] FIG. 2 is a perspective view of an edge polishing apparatus
according to an embodiment of the present invention.
[0025] FIG. 3 is a perspective view of a polishing arm and
polishing head according to an embodiment of the present
invention.
[0026] FIG. 4 is a schematic illustration depicting an example
embodiment of a portion of an edge polishing apparatus in contact
with the edge of the substrate according to the present
invention.
[0027] FIGS. 5A through 5D are close-up perspective views of
different embodiments of backing pads adapted for use with
embodiments of the present invention.
[0028] FIG. 6A is a top cross-sectional view depicting the load arm
in position to apply force on the edge of the substrate according
to an embodiment of the present invention.
[0029] FIG. 6B is a top cross-sectional view depicting the load arm
in a retracted position according to an embodiment of the present
invention.
DETAILED DESCRIPTION
[0030] The present invention provides improved methods and
apparatus for cleaning and/or polishing the edge of a substrate.
The edge of a substrate may be polished by application of an
abrasive polishing tape onto the edge as the substrate is rotated
or otherwise moved (e.g., oscillated). The abrasive polishing tape
may be applied to the edge of the substrate by a polishing head.
According to the present invention, the polishing head may be
positioned at an end of a polishing arm. The polishing arm may
include a rocker arm, adapted to rotate the polishing head about an
axis tangential to the edge of the substrate, providing control
over the contact between the polishing tape and the edge of the
substrate; the polishing arm may also include a pivotable load arm,
adapted to drive the polishing head toward the substrate, forcing
(`loading`) the polishing tape to contact the edge of the
substrate, when pivoted in a first direction, and to retract the
polishing head away from contacting the edge of the substrate when
pivoted in a second, opposite direction.
[0031] It has been found that loading the polishing tape in this
manner improves force control, and provides for rapid
removal/withdrawal of the polishing head from the edge of the
substrate so as to prevent accumulation of particles and/or fluid
on the polishing head, which may otherwise result from prolonged
contact with the edge of the substrate.
[0032] FIG. 1 shows a top view of an exemplary substrate edge
polishing system or `module` (`edge polishing module`) according to
the present invention. The edge polishing module 100 may be
integrated within a larger substrate preparation system (not shown)
for use in an electronic device manufacturing facility. For
example, the substrate preparation system may include a factory
interface for receiving new, unprepared/unprocessed substrates, and
one or more cleaning modules for removing any dust or particles
from the substrate, in addition to polishing modules, such as the
edge polishing module 100. The substrate preparation system may be
used to condition substrates for subsequent processes, such as
etching, deposition, etc.
[0033] The edge polishing module 100 may include a housing 101 in
which one or more edge polishing apparatuses 102, 104, 106 are
positioned. Although the embodiment shown includes three (3)
apparatuses, other numbers of apparatus may be used (e.g., 1, 2, 4,
5, 6, or more). The edge polishing apparatuses 102, 104, 106 may be
positioned surrounding a central platform 108 (shown in FIG. 2)
upon which a substrate 110 may be mounted and supported. The
central platform 108 may be rotatable by a driver 111 (e.g., motor,
gear, belt, chain, etc.) (also shown in FIG. 2) and may include a
vacuum chuck or other mechanism for holding the substrate 110 in
place during rotation of the central platform 108. In the depicted
embodiment, the substrate 110 is disk-shaped having major surfaces
oriented in the horizontal plane. However, in alternative
embodiments, the substrate 110 may have other shapes and
orientations.
[0034] Each edge polishing apparatus 102, 104, 106, may be coupled
to, and supplied with, an abrasive polishing tape (shown in FIG. 2)
by a corresponding set of polishing tape spools 112, 114, 116. Each
set of polishing tape spools 112, 114, 116 may include a supply
spool and a take-up spool (shown in FIG. 2). The supply spools may
store unused polishing tape available to be unwound and pulled into
the corresponding polishing apparatus 102, 104, 106, positioned
adjacent the substrate 110, while the take-up spools may be adapted
to receive used and/or worn polishing tape. One or both of the
supply and take-up spools may be indexed to precisely control the
amount of polishing tape that is advanced to the corresponding edge
polishing apparatus 102, 104, 106. In some embodiments, the
polishing tape may be moved continuously between the spools.
[0035] The edge polishing module 100 may also include a controller
120 (e.g., a software driven computer, a programmed processor, a
microcontroller, a gate array, a logic circuit, an embedded real
time processor, etc.), adapted to direct the operation of the
components of the edge polishing module, including the polishing
apparatuses 102, 104, 106, the driver 111, and the sets of spools
112, 114, 116. In one or more embodiments, each polishing apparatus
102, 104, 106 may be equipped with its own controller. The
controller 120 may include, or be coupled to, memory resources
(e.g., RAM, ROM, flash memory, optical disk, local area network
(LAN) storage) (not shown). In one or more embodiments, the
controller 120 may be adapted to access data related to operation
of the edge polishing module 100, which may be stored in
query-accessible databases stored within the memory resources.
[0036] Each edge polishing apparatus 102, 104, 106 may be adapted
to load the polishing tape forcibly into contact with the edge of
the substrate 110 when supplied with polishing tape from
corresponding sets of spools 112, 114, 116. The sets of spools 112,
114, 116 may be oriented vertically so that the footprint occupied
(i.e., the area occupied and allocated to the equipment within a
manufacturing facility) by the sets of spools 112, 114, 116 is
minimized.
[0037] Turning to FIG. 2, a schematic view of an edge polishing
apparatus, e.g., 102, is depicted. The apparatus 102 may include a
polishing arm 201, aligned in the horizontal plane approximately
tangential to the edge 202 of the substrate 110 and supported by a
frame 203. In other embodiments, the polishing arm 201 may be
aligned differently, for example, vertically or at an angle with
respect to the horizontal plane. The polishing arm 201 may include
a polishing head section 204 (`head`), adapted to forcibly apply
the polishing tape 206 to the substrate edge 202 as the substrate
110 is rotated by the central platform 108, or by some other
mechanism (e.g., drive rollers). The head 204 may be rotated and/or
angularly translated around an axis tangential to the substrate
edge 202 so as to apply force onto the substrate edge 202 at
different angles. The angular translation may be oscillatory, such
that the head 204 `rocks` back and forth over and under the
substrate edge 202. By such rotation and/or angular translation,
the head 204 may bring the polishing tape 206 in contact with top
and bottom bevels (i.e., angled surfaces) on the edge 202 of the
substrate 110, as well as top and bottom exclusion regions, which
may serve as buffers between the edge 202 and the portion of the
substrate 110 allocated for device fabrication, without contacting
portions of the substrate 110 allocated for device fabrication. The
head 204 may include a backing and/or inflatable pad (`backing
pad`) 208, adapted to contact the polishing tape 206 as the
polishing arm 201 forces the head 204 against the rotating
substrate edge 202 via an actuator (not shown). The backing pad 208
may be soft and/or include or develop contours adapted to conform
to the profile of the substrate edge 202. Exemplary embodiments of
backing pads 208 are shown in FIGS. 5A-5D, and described below.
[0038] Edge polishing may be performed using one or more polishing
apparatuses (e.g., 200). In one or more embodiments, a plurality of
polishing apparatuses 200 may be employed, in which each polishing
apparatus 200 may have similar or different characteristics and/or
mechanisms. In the latter case, particular polishing apparatuses
200 may be employed for specific operations. For example, one or
more of a plurality of polishing apparatuses 200 may be adapted to
perform relatively rough polishing and/or adjustments, while
another one or more of the plurality of polishing apparatuses 200
may be adapted to perform relatively fine polishing and/or
adjustments. Polishing apparatuses 200 may be used in sequence so
that, for example, a rough polishing procedure may be performed
initially and a fine polishing procedure may be employed
subsequently to make adjustments to a relatively rough polish as
needed or according to a polishing recipe. The plurality of
polishing apparatuses 200 may be located in a single chamber or
module (e.g., 100), or alternatively, one or more polishing
apparatuses 200 may be located in separate chambers or modules.
Where multiple chambers are employed, a robot or another type of
transfer mechanism may be employed to move substrates between the
chambers so that polishing apparatuses 200 in the separate chambers
may be used in series or otherwise.
[0039] FIG. 3 shows a close-up view of an exemplary embodiment of
the polishing arm 201 according to the present invention. The head
204 is positioned at a first, distal end of the polishing arm 201.
As shown, the head 204 includes a backing block 302 (not visible in
FIG. 3, but see FIG. 4) having an exposed, external surface (not
shown) to which the backing pad 208 is firmly coupled. The head 204
is coupled (e.g., rigidly) to a rocker arm 304, which extends
longitudinally along the polishing arm 201. The rocker arm 304 may
be rotated or `rocked` back and forth in a continuous or
intermittent oscillatory motion around the longitudinal axis 306
(as shown by the curved arrow around axis 306) of the polishing arm
201. In the embodiment depicted, the rocker arm 304 is C-shaped in
cross-section, and thus has a hollow interior. The rocker arm 304
may have other cross-sectional shapes. The rocker arm 304 may be
coupled to a rocker motor 308, via a mounting bracket 310, and
driven by the rocker motor 308 to rotate approximately plus and
minus 90 degrees with respect to a `home` (zero degree) position in
which the backing pad 208 of the head 204 is oriented approximately
perpendicular to the edge 202 of the substrate 110. The rocker arm
304 may be rotated at other angles.
[0040] The polishing arm 201 may further include one or more
mechanical couplings (e.g., washers, rotating bearings, etc.,) (not
shown) positioned within the mounting bracket 310, or between the
mounting bracket 310 and the rocker arm 304, to facilitate the
operation of the rocker motor 308. A sealing plate 312 may be
positioned between the rocker arm 304 and the mechanical couplings
to protect the mechanical couplings and the rocker motor 308 from
contamination (e.g., substrate particles, cleaning fluids)
resulting from the polishing process.
[0041] A load arm 314 may extend longitudinally along the polishing
arm 201 adjacent to the rocker arm 304. In one or more embodiments
in which the rocker arm 304 has a C-shaped cross-sectional profile,
the load arm 314 may be positioned within the interior of the
rocker arm 304. In such embodiments, the rocker arm 304 may rotate
with the load arm 314 around the longitudinal axis 306 of the
polishing arm 201. The distal end of the load arm 314 may be
coupled (e.g., rigidly) to the backing block 302 and the proximal
end of the load arm 314 may be coupled, via a pivot mechanism 316
(shown in FIG. 6A), to an actuator 318. The actuator 318 may
comprise a pneumatic cylinder (as shown), a piezoelectric element,
an electromagnetically-driven piston or any other device capable of
extending or retracting in a linear direction. In one or more
embodiments, the actuator 318 may be positioned at the proximal end
of the polishing arm 201 some distance away from the substrate 110.
It has been found that this configuration protects the actuator 318
from exposure to the wet environment and contaminants resulting
from the polishing process.
[0042] As discussed below, with reference to FIGS. 6A and 6B, the
movement of the actuator 318 may cause the load arm 314 to pivot in
a direction opposite to the direction of movement of the actuator
318, toward or away from the edge 202 of the substrate 110. Due to
the coupling between the load arm 314 and the backing block 302,
the pivoting of the load arm 314 toward the substrate 110 moves the
head 204 (e.g., the backing pad 208 of head 204) into contact with
the edge 202 of the substrate 110, and the pivoting of the load arm
314 away from the substrate 110 causes the head 204 to retract and
move away from the edge 202 of the substrate 110. It has been found
that use of a longitudinally-extending load arm 314 to press the
head 204 against the substrate edge 202 provides a more uniform
angle between the head 204 and the substrate 110 during a stroke of
the load arm 314 compared to conventional techniques.
[0043] Referring again to FIG. 2, as noted above, the polishing
tape 206 may be supplied to the head 204 by a set of spools
including a supply spool 209 and a take-up spool 210. The spools
209, 210 may be driven by one or more drivers (e.g., servo motors)
which may provide an indexing capability to allow a specific amount
of unused polishing tape 206 to be advanced or continuously fed to
the substrate edge, and/or a tensioning capability to allow the
polishing tape 206 to be stretched taught and to apply pressure to
the substrate edge 202. Additionally, the polishing tape 206 may
further be pulled taught by one or more tensioning rollers 212
positioned on the head 204 (as shown), or in other locations. The
tensioning roller(s) 212 may be adapted to apply a variable amount
of tension to the polishing tape 206, and thereby the substrate
edge 202, so as to attain precise control over an edge polishing
process which may be used to compensate for different edge
geometries and changes in the substrate 110 as material is removed
from the substrate edge 202.
[0044] In one or more embodiments, the abrasive component of the
polishing tape 206 may be made from one or more different materials
including, for example, diamond, aluminum oxide, silicon oxide,
silicon carbide, etc. Other materials may also be used. In some
embodiments, the abrasives used in the polishing tape 206 may range
from about 0.25 microns up to about 3 microns in size, although
other sizes may be used. Different widths of polishing tape 206,
ranging from about 0.2 inches to about 1.5 inches, may be used
(although other widths may be used). In one or more embodiments,
the polishing tape 206 may be about 0.002 to about 0.02 of an inch
thick, and be able to withstand about 1 to 5 lbs. of tension in
embodiments that use a pad, and from about 3 to about 8 lbs. of
tension in embodiments without a pad. Other tapes having different
thicknesses and strengths may be used. In some embodiments, the
spools 209, 210 may be approximately 1 inch to approximately 4
inches in diameter, hold up to approximately 5000 inches of
polishing tape 206, and may be constructed from any practicable
materials such as polyurethane, polyvinyl difloride (PVDF), etc.
Other materials may be used. The spools 209, 210 may also have
other dimensions and hold other amounts of polishing tape 206.
[0045] In some embodiments, the polishing apparatuses 102, 104, 106
of the edge polishing module 100 may support different types of
polishing tapes (e.g., tapes of different abrasive grits) which may
be used concurrently, in a predefined sequence, or at different
times. The heads 204 of the polishing apparatuses 102, 104, 106 may
also be disposed in different positions to allow the supported
tapes to polish different portions of the edge 202 of the rotating
substrate 110.
[0046] Turning to FIG. 4, a schematic close-up illustration of a
polishing contact between the polishing tape 206 and the edge 202
of the substrate 110 is depicted. As shown, the polishing tape 206
may be pressed against (e.g., as indicated by arrow 402) and
contour to the edge 202 of the substrate 110. The substrate 110 may
be rotated against the polishing tape 206 at a rate ranging from
about 50 to about 1000 RPM, for example, although other rates may
be used. The polishing tape 206 may contact the edge 202 of the
substrate 110 for about 15 to 150 seconds, depending on the type of
tape used, the grit of the tape, the rate of rotation, the amount
of polishing required, etc. More or less time may be used. As
shown, the polishing tape 206 is supported by the backing pad 208,
disposed adjacent a backside (e.g., a non-abrasive side) of the
polishing tape 206. The backing pad 208 may be pressed toward the
substrate edge 202 by the backing block 302 (which may, in turn, be
forced by an actuator 318 (shown in FIG. 3)). The pressure on the
backing pad 208 may cause the backing pad 208 and/or the polishing
tape 206 to contour to the substrate edge 202. Thus, the friction
(i.e., abrading contact) between the polishing tape 206 and the
substrate edge 202 may include two elements: the torque exerted
during rotation of the substrate 110 against the polishing tape
206, and the force exerted in pressing the polishing tape 206 onto
the edge 202 of the substrate 110. In some embodiments, the
combined force at the point(s) of contact may range from about 0.5
lbs. to about 4 lbs. Other amounts of force may be used.
[0047] In some embodiments, one or more fluid channels 404 (e.g., a
spray nozzle or bar) may be provided to deliver chemicals and/or
water to aid in the polishing/cleaning of the substrate edge 202,
lubricate the substrate 110, and/or to wash away removed material.
The fluid channel 404 may be adapted to deliver fluid to the
substrate 110, to the polishing tape 206, and/or to the pad 208.
The fluids may include deionized water which may serve as a
lubricant and to flush particles away. A surfactant and/or other
known cleaning chemistries may also be included. In some
embodiments, sonic (e.g., megasonic) nozzles may be used to deliver
sonicated fluids to the substrate edge 202 to supplement the
cleaning. Fluid may also be delivered through the polishing tape
206 and/or pad 208 to the substrate edge 202.
[0048] Turning to FIGS. 5A-5D, different exemplary embodiments of
backing pads 208A, 208B, 208C and 208D are depicted. In addition to
the backing pad 208 (as shown FIG. 4) that has a flat surface
co-planar with the polishing tape 206 when the substrate 110 is not
present, the backing pad 208A (shown in FIG. 5A) may include a
concave surface that matches the contour of the edge 202 of the
substrate 110. Alternatively, as shown in FIG. 5B, the backing pad
208B (shown in FIG. 5B) may include a double concave surface to
better match the contour of the edge 202 of the substrate 110.
[0049] In some embodiments, as shown in FIG. 5C, the backing pad
208C may have an adjustable amount of ability to conform to the
substrate's edge 202. For example, the backing pad 208C may include
an inflatable bladder 501, such that by adding more air or liquid
or other fluid, the pad 208C may become harder, and by reducing the
amount of air or liquid or other fluid in the bladder 501, the pad
208C may become more conforming. The bladder 501 may be filled
(and/or emptied) via a fluid channel 502 with fluid from a fluid
supply 504. In some embodiments, the fluid supply 504 may
inflate/deflate the bladder 501 under the direction of an operator
or a programmed and/or user operated controller. In such
embodiments, an elastomeric material, such as silicon rubber or the
like, may be used for the bladder 501 to further enhance the pad's
208C ability to stretch and conform to the substrate edge 202. Such
an embodiment may allow an operator/controller to precisely control
the surface area of contact between the polishing tape 206 and the
substrate edge 202 by, e.g., limiting the amount of fluid pumped
into the bladder 501. For example, once the substrate edge 202 is
placed against the pad 208C with a deflated bladder 501, the
bladder 501 may be inflated so that the pad 208C is forced to wrap
around, and conform to, the polished and/or cut surfaces of the
substrate edge 202, such as bevels or outer edges, and excluded
regions (`edge exclusion zone`) without wrapping around, or
extending to, regions of the substrate 110 reserved for device
fabrication. Note that in some embodiments, multiple bladders may
be used in the pad 208, and that differently shaped inflatable
bladders 501 may be used within differently shaped pads (e.g., 208,
208A, 208B).
[0050] FIG. 5D shows an embodiment of a `rolling` backing pad 208D,
which is formed in the shape of a wheel. The rolling backing pad
208D may be inflatable and/or rigid or inflatable and/or
conforming. The rolling backing pad 208D may affect (e.g., increase
or decrease) the frictional forces acting on the motion of the
polishing tape 206 by rotating as the polishing tape 206 is
indexed, and may thereby improve polishing performance.
[0051] The backing pads 208, 208A, 208B, 208C, 208D may be made of
materials such as, for example, an acetal resin (e.g., Delrin.RTM.
manufactured by DuPont Corporation), PVDF, polyurethane closed cell
foam, silicon rubber, etc. Other materials may be used. Such
materials may have resilience, or an ability to conform, that is a
function of the thickness or density of the pad 208. The material
may be selected based upon its resilience. The desired resilience
may be selected based upon the type of polishing required. Any or
all of the backing pads 208, 208A, 208B, 208C and 208D may be
mounted off-center on the polishing head 204 to, for example,
polish different areas on top and bottom surface of the substrate
110 or substrate edge 202.
[0052] As noted above with respect to FIG. 5C, in some embodiments,
fluids used to aid in the polishing may be delivered to the
substrate edge 202 via the pads 208, 208A, 208B, 208C, 208D. While
the fluid channel 502 shown in FIG. 5C is coupled to the bladder
501, in alternate embodiments, the fluid channel 502 may be
provided to drip or spray the fluid on or into the pads.
Alternatively, the bladder 501 shown in FIG. 5C may have a
semi-permeable membrane that allows fluid to be slowly released and
transmitted to the polishing tape 206 (e.g., through the pad). In
such embodiments, the pads 208, 208A, 208B, 208C, 208D may be
covered by, made of, and/or include material that absorbs and/or
retains the fluids used (e.g., polyvinyl alcohol (PVA), etc.).
[0053] FIG. 6A is a cross-sectional top view illustrating the load
arm 314 of the polishing arm 201 according to an embodiment of the
present invention, positioned to apply force onto the polishing
tape 206 (not shown) and substrate edge 202 via the polishing head
204 and backing pad 208. As shown, in operation, when the actuator
318 (e.g., pneumatic cylinder) retracts in a direction (shown by
the arrow on the right hand side of FIG. 6A) generally
perpendicular to the longitudinal axis of the polishing arm 201 and
away from the substrate 110 (for example, in response to an
electrical or electromechanical signal), the retraction may cause a
counter-clockwise motion of the pivot mechanism 316. In turn, the
counter-clockwise motion of the pivot mechanism 316 may cause a
forward motion of the load arm 314 towards the substrate 110 (as
shown by the arrow on the left hand side of FIG. 6A). The forward
motion of the load arm 314 may bring the head 204, backing pad 208,
and polishing tape 206 (not shown) into contact with the edge 202
of the substrate 110. In other words, the load arm 314 may move the
head 204 in a direction perpendicular, or substantially
perpendicular, to the longitudinal axis 306 of the polishing arm
201. In some embodiments, the perpendicular motion may be achieved
with a linear load arm, or may be approximated by a rotary load
arm.
[0054] FIG. 6B is a cross-section top view illustrating the load
arm 304 in a retracted position. In operation, when the actuator
318 extends in a direction perpendicular to the longitudinal axis
of the polishing arm 201 and towards the substrate 110 (for
example, in response to an electrical or electromechanical signal),
the extension may cause a clockwise motion of the pivot mechanism
316. In turn, the clockwise motion of the pivot mechanism 316 may
cause a backward motion of the load arm 314 away from the substrate
110, retracting the head 204 and backing pad 208. In this retracted
position, no force is applied by the head 204 onto the polishing
tape 206, and polishing does not occur.
[0055] The operation of the actuator 318 may be directed by the
controller 120, which may be adapted to determine an amount of
force to apply to the substrate 110, and amount of time to apply
such force, etc.
[0056] The foregoing description discloses only exemplary
embodiments of the invention. Modifications of the above disclosed
apparatus and methods which fall within the scope of the invention
will be readily apparent to those of ordinary skill in the art. For
example, while the rotational axis of the rocker arm 304 has been
shown to be coplanar and tangential to the edge 202 of the
substrate 110, the rotational axis may be offset towards or away
from the center of the substrate 110 to change polishing
characteristics at or near the edge exclusion zone of the substrate
110.
[0057] Moreover, although only examples of cleaning a round
substrate are disclosed, the present invention could be modified to
clean substrates having other shapes (e.g., a glass or polymer
plate for flat panel displays). Further, although processing of a
single substrate by the module is shown above, in some embodiments,
the module may process a plurality of substrates concurrently.
[0058] Accordingly, while the present invention has been disclosed
in connection with exemplary embodiments thereof, it should be
understood that other embodiments may fall within the spirit and
scope of the invention, as defined by the following claims.
* * * * *