U.S. patent application number 12/124147 was filed with the patent office on 2008-11-27 for methods and apparatus for using a rolling backing pad for substrate polishing.
This patent application is currently assigned to APPLIED MATERIALS, INC.. Invention is credited to Paul D. Butterfield, Shou-Sung Chang, Gary C. Ettinger, Sen-Hou Ko, Eashwer Kollata, Antoine P. Manens, Ricardo Martinez, Zhenhua Zhang.
Application Number | 20080293341 12/124147 |
Document ID | / |
Family ID | 40072859 |
Filed Date | 2008-11-27 |
United States Patent
Application |
20080293341 |
Kind Code |
A1 |
Kollata; Eashwer ; et
al. |
November 27, 2008 |
METHODS AND APPARATUS FOR USING A ROLLING BACKING PAD FOR SUBSTRATE
POLISHING
Abstract
An apparatus and method are provided to polish an edge of a
substrate. The invention includes a polishing head including a
backing pad, wherein a width of the backing pad that contacts the
substrate edge is larger than a width of a notch in the substrate
edge. Numerous other aspects are provided.
Inventors: |
Kollata; Eashwer;
(Sunnyvale, CA) ; Chang; Shou-Sung; (Stanford,
CA) ; Zhang; Zhenhua; (San Jose, CA) ;
Butterfield; Paul D.; (San Jose, CA) ; Ko;
Sen-Hou; (Sunnyvale, CA) ; Manens; Antoine P.;
(Sunnyvale, CA) ; Ettinger; Gary C.; (Cupertino,
CA) ; Martinez; Ricardo; (Manteca, 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: |
40072859 |
Appl. No.: |
12/124147 |
Filed: |
May 21, 2008 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
60939344 |
May 21, 2007 |
|
|
|
Current U.S.
Class: |
451/285 ;
451/289; 451/44 |
Current CPC
Class: |
B24B 21/002 20130101;
B24B 9/065 20130101 |
Class at
Publication: |
451/285 ;
451/289; 451/44 |
International
Class: |
B24B 5/00 20060101
B24B005/00; B24B 1/00 20060101 B24B001/00 |
Claims
1. An apparatus for polishing an edge of a substrate comprising: a
polishing head including a backing pad, wherein a width of the
backing pad that contacts a substrate edge is larger than a width
of a notch in the substrate edge.
2. The apparatus of claim 1 wherein the backing pad is
cylindrically shaped.
3. The apparatus of claim 2 wherein the backing pad includes a bore
therethrough.
4. The apparatus of claim 3 further comprising a roller.
5. The apparatus of claim 4 wherein the backing pad is mounted on
the roller via the bore.
6. The apparatus of claim 5 wherein the backing pad is adapted to
rotate about the roller.
7. The apparatus of claim 1, wherein the backing pad is adapted to
conform to the substrate edge.
8. The apparatus of claim 1 wherein the polishing head is adapted
to rock about the substrate edge.
9. The apparatus of claim 1 wherein the backing pad is adapted to
press a polishing tape against the substrate edge.
10. A system for polishing an edge of a substrate comprising: a
substrate support adapted to rotate a substrate; a polishing head
including a backing pad, wherein a width of the backing pad that
contacts the substrate edge is larger than a width of a notch in
the substrate edge; and a controller adapted to operate the
rotation of the substrate and the polishing head.
11. The system of claim 10 wherein the backing pad is cylindrically
shaped.
12. The system of claim 11 wherein the backing pad includes a bore
therethrough.
13. The system of claim 12 further comprising a roller.
14. The system of claim 13 wherein the backing pad is mounted on
the roller via the bore.
15. The system of claim 10, wherein the backing pad is adapted to
conform to the substrate edge.
16. The system of claim 10 wherein the polishing head is adapted to
rock about the substrate edge.
17. The system of claim 10 wherein the backing pad is adapted to
press a polishing tape against the substrate edge.
18. A method for polishing an edge of a substrate comprising:
rotating a substrate; and contacting an edge of the substrate with
a backing pad, wherein a width of the backing pad that contacts the
substrate edge is larger than a width of a notch in the substrate
edge the backing pad.
19. The method of claim 18 further comprising: pressing a polishing
tape against the substrate edge with the backing pad.
20. The method of claim 19 further comprising: advancing the
polishing tape in increments.
21. The method of claim 19 further comprising: advancing the
polishing tape continuously.
22. The method of claim 18 wherein the polishing pad is coupled to
a polishing head.
23. The method of claim 22 further comprising: rocking the
polishing head about the edge of the substrate.
24. The method of claim 18 further comprising: rotating the backing
pad about a roller.
25. The method of claim 18 further comprising: determining that a
pre-set amount of film has been removed from the substrate edge.
Description
[0001] The present application claims priority from U.S.
Provisional 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) which 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. 11/693,695, filed on Mar.
29, 2007, and entitled "METHODS AND APPARATUS FOR POLISHING AN EDGE
OF A SUBSTRATE" (Attorney Docket No. 10560);
[0006] 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);
[0007] 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);
[0008] 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);
[0009] 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);
[0010] 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);
[0011] 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);
[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
cleaning an edge of a substrate.
BACKGROUND OF THE INVENTION
[0018] Substrates are used in semi-conductor device manufacturing.
During processing, the edge of the substrate may become dirty which
may negatively affect the semi-conductor devices on the substrate.
Conventional systems may contact a substrate edge with an abrasive
film or tape, as the substrate rotates, to clean the edge. However,
the substrate may include a notch in the edge to aide in the proper
alignment of the substrate during processing. Conventional systems
may not take the notch into account when cleaning the substrate
edge, and the impact of the abrasive tape on the rotating substrate
may result in damage to the notch. Accordingly improved methods and
apparatus for cleaning an edge of a substrate are desired.
SUMMARY OF THE INVENTION
[0019] In aspects of the invention, an apparatus is provided for
polishing an edge of a substrate. The apparatus comprises a
polishing head including a backing pad, wherein a width of the
backing pad that contacts the substrate edge is larger than a width
of a notch in the substrate edge. In some other aspects of the
invention, a system is provided for polishing an edge of a
substrate. The system comprises a substrate support adapted to
rotate a substrate; a polishing head including a backing pad,
wherein a width of the backing pad that contacts the substrate edge
is larger than a width of a notch in the substrate edge; and a
controller adapted to control rotation of the substrate and the
polishing head.
[0020] In yet other aspects of the invention, a method is provided
for polishing an edge of a substrate. The method comprises rotating
a substrate and contacting an edge of the substrate with a backing
pad, wherein a width of the backing pad that contacts the substrate
edge is larger than a width of a notch in the substrate edge the
backing pad.
[0021] Other features and aspects of the present invention will
become more fully apparent from the following detailed description,
the appended claims and the accompanying drawings.
BRIEF DESCRIPTION OF THE FIGURES
[0022] FIG. 1 is a schematic illustration of a cross-section of a
portion of a substrate, including a notch.
[0023] FIG. 2 is a schematic plan view of an example embodiment of
an edge cleaning system according to the present invention.
[0024] FIG. 3 is a schematic perspective view of an embodiment of a
polishing apparatus for polishing a substrate edge according to the
present invention.
[0025] FIG. 4 is a perspective view of a backing pad according to
the present invention.
[0026] FIG. 5 is a schematic illustration of the backing pad
according to the present invention.
[0027] FIG. 6 is a flowchart depicting an example application of
the present invention.
DETAILED DESCRIPTION
[0028] 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 pad or abrasive polishing tape contacting the
substrate edge via a polishing pad or head, for example, as the
substrate is rotated or otherwise moved (e.g., oscillated).
According to the present invention, the width of the polishing or
backing pad may be large enough such that the backing pad spans
beyond the width of the notch in the substrate edge. This extended
width may prevent the backing pad from entering into and/or
damaging the notch as the substrate edge is polished.
[0029] With reference to FIG. 1, a substrate 100 may include two
major surfaces 102, 102' and an edge 104. Each major surface 102,
102' of the substrate 100 may include a device region 106, 106' and
an exclusion region 108, 108'. (Typically however, only one of the
two major surfaces 102, 102' will include a device region and an
exclusion region.) The exclusion regions 108, 108' may serve as
buffers between the device regions 106, 106' and the edge 104. The
edge 104 of a substrate 100 may include an outer edge 110 and
bevels 112, 114. The bevels 112, 114 may be located between the
outer edge 110 and the exclusion regions 108, 108' of the two major
surfaces 102, 102'. A notch 116 may be located in the outer edge
110 of the substrate 100 and be used to align/position the
substrate 100 during various processing steps (e.g., lithography,
deposition, etching, cleaning, etc.). The present invention is
adapted to clean and/or polish the outer edge 110 and at least one
bevel 112, 114 of a substrate 100 without affecting the notch 116
or the device regions 106, 106'. In some embodiments, all or part
of the exclusion regions 108, 108' may be cleaned or polished as
well.
[0030] FIG. 2 is a schematic plan view of an embodiment of a system
200 for polishing parts of the substrate 100, including the major
surfaces 102, 102' and the substrate edge 104.
[0031] The system 200 of FIG. 2 includes three polishing
apparatuses 202, each including a polishing head 204. However, any
number and type of apparatus 202/heads 204 may be used in any
practicable combination. In addition, in such multi-head
embodiments, each head 204 may use a differently configured or
different type of a polishing tape (e.g., different grits,
materials, tensions, pressures, etc.) to contact and polish the
substrate edge 104. Any number of heads 204 may be used
concurrently, individually, and/or in any sequence. The heads 204
may be disposed in different positions and in different
orientations (e.g., aligned with the substrate edge 104, normal to
the substrate edge 104, angled relative to the substrate edge 104,
etc.) to allow polishing tape, pushed by a pad in some embodiments
(e.g., as depicted in FIG. 3), to polish different portions of the
edge 104 of the substrate 100. In some embodiments, one or more of
the heads 204 may be adapted to be oscillated or moved (e.g.,
angularly translated about a tangential axis of the substrate 100
and/or circumferentially relative to the substrate 100) around or
along the substrate edge 104 so as to polish different portions of
the substrate edge 104. In some embodiments, one or more of the
heads 204 may be adapted to continuously or intermittently
oscillate between the various positions. Alternatively, one or more
of the heads 204 may be fixed and/or only adjusted while the
substrate 100 is not being rotated. In yet other embodiments, the
substrate 100 may be held fixed while one or more of the heads 204
oscillate (as described above) as well as rotate circumferentially
around the substrate 100. This movement may be under the direction
of a programmed or user operated controller 205, further described
below. Different heads 204 may be used for different substrates 100
or different types of substrates 100. As described above, the
system 200 may further include the controller 205, (e.g., a
programmed computer, a programmed processor, a microcontroller, a
gate array, a logic circuit, an embedded real time processor,
etc.), which may control the driver(s) used to rotate the substrate
100 and/or the actuator(s) used to push a polishing pad(s) (FIG. 3)
against the substrate edge 104. Note that the controller 205 may be
coupled (e.g., electrically, mechanically, pneumatically,
hydraulically, etc.) to each of a plurality of actuators. Likewise,
the controller 205 may be adapted to receive feedback signals from
one or more drivers and/or actuators, that indicate the amount of
energy being exerted to rotate the substrate 100 (e.g., rotate a
vacuum chuck holding the substrate 100) and/or actuate the
actuator(s) to push the polishing pad(s) against the substrate 100.
These feedback signals may be employed to determine when a
particular layer of film has been removed and/or whether a
sufficient amount of polishing has occurred.
[0032] As mentioned above, substrate polishing may be performed
using one or more polishing apparatuses 202. In one or more
embodiments, a plurality of polishing apparatuses 202 may be
employed, in which each polishing apparatus 202 may have similar or
different characteristics and/or mechanisms. In the latter case,
particular polishing apparatuses 202 may be employed for specific
operations. For example, one or more polishing apparatuses 202 may
be adapted to perform relatively rough polishing and/or adjustments
while another one or more polishing apparatus 202 may be adapted to
perform relatively fine polishing and/or adjustments. Polishing
apparatuses 202 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 202 may
be located in a single chamber or module, as shown herein, or
alternatively, one or more polishing apparatuses 202 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 100 between the chambers so that
polishing apparatuses 202 in the separate chambers may be used in
series or otherwise.
[0033] FIG. 3 is a schematic perspective view of an embodiment of a
polishing apparatus 300 for polishing a substrate edge 104. The
polishing apparatus 300 may include a substrate driver 302 (e.g., a
servomotor, gear, belt, chain, etc.), which may be mounted on a
pedestal 304. A support 306 (e.g., a vacuum chuck) may be coupled
(e.g., rigidly) to a shaft (not shown) of the substrate driver 302.
The support 306 may support the substrate 100, for example. The
substrate driver 302 may rotate the substrate 100, via the support
306, about a center 308 of the substrate 100 or another suitable
axis. The substrate driver 302 may be connected to a substrate
driver control unit, such as the controller 205, for example, which
may control the angular displacement, angular velocity, and angular
acceleration of the substrate 100.
[0034] Additionally, unlike some embodiments which may include one
or more drive rollers (not shown) and guide rollers (not shown)
that are adapted to rotate the edge 104 of the substrate 100
against the polishing tape 318, described below, an advantage of an
embodiment using a vacuum chuck is that the apparatus 300 does not
need to contact the substrate edge 104 being polished. Thus, the
potential of particles accumulating on drive rollers, used in other
embodiments to rotate the substrate, and being re-deposited on the
substrate edge 104 is eliminated. The need to clean rollers also is
eliminated. Further, the possibility of rollers damaging or
scratching the edge is also eliminated. By holding the substrate
100 in a vacuum chuck, high speed rotation without significant
vibration may be achieved.
[0035] The polishing apparatus 300 may further include a polishing
arm 310 aligned in the horizontal plane approximately tangential to
an edge of the substrate 100, and supported by a frame 312. The
frame 312 may be coupled at one end to a polishing head driver 309.
In other embodiments, the polishing arm 310 may be aligned
differently, for example, vertically, or at an angle, with respect
to the horizontal plane. The polishing arm 310 may include a
polishing head section 314 (`head`). The polishing head 314 may
include a backing or polishing pad 316 and/or inflatable pad. In
either case, the pad 316 and/or inflatable pad may be soft and/or
include or develop contours to conform to the shape of the
substrate edge 104. The polishing pad 316 may be wheel-shaped, as
shown herein, for example. Other shapes may be used. The polishing
pad 316 may be moved towards or away from the substrate 100 by an
actuator (e.g., hydraulic actuator, pneumatic actuator, servomotor,
etc.) (not shown). The actuator may be under the control of the
controller 205, for example. The actuator may rock the head 314
between a desired angle, including for example .+-.90 degrees,
thereby contacting the entire edge 104 of the substrate 100 with
the polishing tape 318. Other angles may be used. In operation,
this is achieved by angularly translating the head 314 and
consequently, a portion of polishing tape 318 in contact with and
contoured to the substrate edge 104, around an axis that is
tangential to the outer edge 110 of the substrate 100 as it is
rotated. Alternatively, a biasing device (e.g., a spring) may be
employed to mount the polishing pad 316 to the head 314 to provide
flexible/dynamic counter pressure to the polishing pad 316.
Polishing tape 318, may wrap around the polishing head 314, and
guide rollers 320, 322 and over the polishing pad 316, and be
tensioned between spools 324, 326. The spools 324, 326 may be
driven by spool drivers 328, 330 (e.g., servomotors), respectively.
The spool drivers 328, 330, may be moved continuously or indexed to
precisely control the amount of the polishing tape 318 that is
advanced over the polishing head 314 from, for example, the spools
324, 326, in order to polish the substrate edge 104. The substrate
100 may contact the abrasive tape 318 for 15 to 150 seconds
depending on the type of tape 318 used, the grit of the tape, the
rate of rotation, the amount of polishing required, etc. More or
less time may be used.
[0036] Depending on the amount of force applied by the actuator,
the resiliency of the pad selected, the amount of inflation of an
inflatable pad, and/or the amount of tension on the tape, a
controlled amount of pressure may be applied to polish the edge
104. Thus, the present invention provides precise control of an
edge polish process, which may be used to compensate for different
edge geometries and changes in the substrate 100 as material is
removed from the edge 104.
[0037] In one or more embodiments, the polishing tape 318 may be
made from many different materials, such as aluminum oxide, silicon
oxide, silicon carbide, etc. Other materials may also be used. In
some embodiments, abrasives used may range, for example, from about
0.5 microns up to about 3 microns in size or 0.1 microns to 10
microns in size, although other sizes may be used. Different widths
of polishing tape 318 ranging from about 0.2 inches to about 1.5
inches may be used, although other polishing tape widths may be
used. In one or more embodiments, the polishing tape 318 may be
about 0.002 to about 0.02 inches thick and withstand about 1 to 5
lbs. in tension. Other tapes having different thicknesses and
tensile strengths may be used. The spools 324, 326 may have a
diameter of approximately 1 inch and be capable of holding about
500 inches of polishing tape 318, for example, or may have a
diameter of approximately 3 inches and be capable of holding about
30,000 inches of polishing tape 318, for example. Other spool
dimensions may be used. The spools 324, 326 may be constructed from
materials such as nylon, polyurethane, polyvinyl difluoride (PVDF),
etc. Other materials may also be used.
[0038] The polishing pad 316 may be made of material 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 a
resilience or an ability to conform that is a function of the
thickness or density of the polishing pad. The material may be
selected based upon its resilience. The material may be selected
based upon other qualities. The desired resilience may be selected
based upon the type of polishing required. The desired resilience
may be selected based upon other criteria.
[0039] In some embodiments, fluids used to aid in the polishing or
washing away of accumulated particles, may be delivered to the
substrate edge 104. The chemicals may be sprayed directly onto the
substrate 100, at the substrate/abrasive tape interface, and/or may
be applied to and/or through the tape and/or the polishing pad 316.
A fluid channel may be provided to drip or spray the fluid on or
into the polishing pads 316. Alternatively, an inflatable pad may
include a bladder with a semi-permeable membrane that allows fluid
to be slowly released and transmitted to the abrasive tape (e.g.,
through the pad). In such embodiments, the pad 316 may be covered
by, made of, and/or include material that absorbs and/or retains
the fluids used (e.g., polyvinyl alcohol (PVA), etc.).
Additionally, the present invention may employ gravity or suction
to cause the runoff not to contaminate or contact other parts of
the substrate 100 or apparatus of the invention. Further, energy
(e.g., megasonic energy) may be applied to the substrate edge 104
via fluid carrying such energy.
[0040] The substrate 100 may be rotated in a horizontal plane. The
edge 104 of the substrate 100 may be aligned with or normal to the
polishing tape 318, polishing pad 316 and/or polishing head 314. In
additional or alternative embodiments, the substrate 100 may be
rotated in a vertical plane, other non-horizontal plane, and/or be
moved between different planes of rotation.
[0041] Turning to FIG. 4, the present invention provides an
exemplary backing pad 400 for use with an abrasive polishing film
or tape 500, shown in FIG. 5, to clean the edge 104 of the
substrate 100. In the embodiment shown herein, the backing pad 400
is contoured in a concave shape forming essentially a concave
cylinder. Other shapes may be used. In some embodiments, the
backing pad 400 may have a radius of approximately 150 mm, for
example. Other suitable radii may be used. The backing pad 400 may
be designed to be wide enough that it spans beyond the width of the
notch 116 as it polishes the substrate edge 104, as shown in FIG.
5. This may ensure that the backing pad 400 does not "fall" or
enter into the notch 116 during polishing, and cause damage to the
notch 116 or edge 104 of the substrate 100 as a result of the
impact. Additionally, to further prevent damage to the substrate
100, the backing pad 400 may be made from a soft material, for
example, with less than Shore A 70 durometer, such as polueurethene
70 which has a hardness of Shore A 60 durometer. Other degrees of
softness may be used. The softness of the backing pad material may
also permit compression of the backing pad 400, which may aid in
polishing the bevels 112, 114 of the substrate 100.
[0042] The backing pad 400 may be hollow or may include a bore
therethrough, which may permit the backing pad 400 to be mounted on
a cylindrical roller 402. Other roller shapes may be used. The
backing pad 400 and the roller 402 may be positioned in the
polishing head 314, shown in FIG. 3. When the roller 402 is
positioned in the polishing head 314, a clearance of 0.5 mm, for
example, on each side of the roller 402 adjacent the backing pad
400 may be included to allow for adjustments in case of errors in
the alignment of the notch 116 with the backing pad 400. Other
measurements providing sufficient clearance may be used.
[0043] Turning to FIG. 5, a schematic illustration of the backing
pad 400 shown in FIG. 4 is provided. In operation, the backing pad
400, pushed by an actuator (not shown), may press the polishing
tape 500 (only a portion shown in cross-section) against the
substrate edge 104 to polish the substrate edge 104. Both the
backing pad 400 and the roller 402 may be able to rotate freely
with the polishing tape 500, to aid the polishing tape 500 in
polishing the edge 104. In other words, the rotation of the backing
pad 400 with the polishing tape 500 may create less friction
therebetween than with a non-rotating backing pad, for example,
which may drag the polishing tape 500. The decreased friction may
result in less wear and tear on the polishing tape 500, for
example, thereby increasing the usable life of the polishing tape
500. Additionally, the decreased friction may result in a decrease
of particle formation. Particle formation may be undesirable due to
its ability to interfere with the polishing system components and
substrate production.
[0044] In some embodiments, as described above, the backing pad 400
may be concave. In such embodiments, the radius of curvature of the
concavity may be selected to match the curvature of the
circumference of the substrate 104 to be polished. Thus, for
example, for a 300 mm substrate, the radius of curvature of the
concavity may be approximately 150 mm, for a 200 mm substrate, the
radius of curvature of the concavity may be approximately 100 mm,
and for a 400 mm substrate, the radius of curvature of the
concavity may be approximately 200 mm. Other radii of curvature may
be used for these various example sizes of substrates. For example,
a radius of curvature that is slightly larger than the radius of
curvature of the substrate may be selected to account for the
polishing tape 500 and/or allow the notch 116 to move past the
backing pad 116 more easily (e.g., without catching an edge of the
polishing tape). In some embodiments, the ends of the backing pad
400 may be rounded as depicted in FIG. 5. By having the ends of the
backing pad 400 rounded, the notch 116 may more easily pass by the
backing pad 400. In addition, the edges of the polishing tape 500
may conform to the rounded ends of the backing pad 400 so that the
notch 116 has less of an opportunity to catch an edge of the
polishing tape 500 as the notch 116 passes the backing pad 400.
[0045] The entire substrate 100 may be rotated as the polishing
tape 500 is pressed against the substrate edge 104, such that the
entire circumference of the substrate edge 104 is polished.
[0046] As described above, the backing pad 400 may be wide enough
to span beyond the notch 116 and polish the substrate edge 104 as
well. If the backing pad 400 was too narrow, when the backing pad
400 contacts the notch 116 as the substrate 100 rotates, the
backing pad 400 may "fall" into or contact the notch 116 at an
angle, and may damage the sides of the notch 116. Additionally, if
the backing pad 400 were to "fall" entirely within the notch 116,
the backing pad 400 may damage the notch 116 as the backing pad 400
is moved out of the notch 116 as the substrate 100 rotates.
[0047] Turning to FIG. 6, an exemplary method 600 for polishing the
edge of a substrate is provided. In step S102, the substrate 100 is
rotated. In step S104, the backing pad 400 presses the polishing
tape 500 against the substrate edge 104. In step S106, the
polishing head 314 (and consequently the backing pad 400) rocks
about the substrate edge 104. In step S108, the polishing tape 500
is advanced. As described above, the polishing tape 500 may be
advanced continuously or in increments. In step S110 the backing
pad is rotated about the roller 402. As described above, the
rotation of the backing pad 400 with the polishing tape 500 may
create less friction therebetween than with a non-rotating backing
pad, for example, which may drag the polishing tape 500. The
decreased friction may result in less wear and tear on the
polishing tape 500, for example, thereby increasing the usable life
of the polishing tape 500. Additionally, the decreased friction may
result in a decrease of particle formation, as particle formation
may be undesirable due to its ability to interfere with the
polishing system components and substrate production. In step S112,
it is determined whether a pre-set amount of film has been removed
from the substrate edge. As described above, the controller 205 may
receive feedback signals from the driver and/or actuator. The
feedback signals may be used to determine when a particular layer
of film has been removed and/or whether a sufficient amount of
polishing has occurred.
[0048] It should be understood that the inventive edge polishing
apparatus described herein may be employed in apparatuses other
than those adapted for bevel and edge polishing and/or removal of
films on substrates. Further, as will be apparent to those of
ordinary skill in the art, the apparatus describe herein may be
employed to polish and/or remove films on an edge of a substrate
supported in any orientation (e.g., horizontal, vertical, diagonal,
etc).
[0049] Further, it should be understood that 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 apparatus is shown above,
in some embodiments, the apparatus may process a plurality of
substrates concurrently.
[0050] 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.
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.
* * * * *