U.S. patent application number 12/124133 was filed with the patent office on 2008-11-27 for methods and apparatus for polishing a notch of a substrate by substrate vibration.
This patent application is currently assigned to APPLIED MATERIALS, INC.. Invention is credited to Sen-Hou Ko, Zhenhua Zhang.
Application Number | 20080293337 12/124133 |
Document ID | / |
Family ID | 40072856 |
Filed Date | 2008-11-27 |
United States Patent
Application |
20080293337 |
Kind Code |
A1 |
Zhang; Zhenhua ; et
al. |
November 27, 2008 |
METHODS AND APPARATUS FOR POLISHING A NOTCH OF A SUBSTRATE BY
SUBSTRATE VIBRATION
Abstract
Apparatus and methods are provided for polishing a notch on an
edge of a substrate. An exemplary apparatus may include a substrate
support adapted to support a substrate; a polishing head adapted to
contact a notch in an edge of the substrate; and a controller
adapted to oscillate the substrate between at least first and
second oscillatory positions while the polishing head contacts the
substrate notch. Numerous other aspects are provided.
Inventors: |
Zhang; Zhenhua; (San Jose,
CA) ; Ko; Sen-Hou; (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: |
40072856 |
Appl. No.: |
12/124133 |
Filed: |
May 20, 2008 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
60939228 |
May 21, 2007 |
|
|
|
Current U.S.
Class: |
451/44 ;
451/163 |
Current CPC
Class: |
B24B 9/065 20130101;
B24B 1/04 20130101 |
Class at
Publication: |
451/44 ;
451/163 |
International
Class: |
B24B 1/00 20060101
B24B001/00 |
Claims
1. An apparatus for polishing a notch in a substrate edge
comprising: a substrate support adapted to support a substrate; a
polishing head adapted to contact a notch in an edge of the
substrate; and a controller adapted to oscillate the substrate
between at least first and second oscillatory positions while the
polishing head contacts the substrate notch.
2. The apparatus of claim 1 wherein the polishing head includes a
backing pad.
3. The apparatus of claim 2 further comprising a polishing tape,
wherein the backing pad is adapted to contact the substrate notch
with the polishing tape.
4. The apparatus of claim 3 further comprising a motor adapted to
advance the polishing tape, thereby creating relative movement
between the polishing tape and the substrate notch.
5. The apparatus of claim 2 wherein the backing pad includes a
protruding member.
6. The apparatus of claim 5 wherein the protruding member is
adapted to be pressed into the substrate notch.
7. The apparatus of claim 5 wherein the protruding member is
conformable to the shape of the substrate notch.
8. The apparatus of claim 1 wherein the first oscillatory position
is at a first oscillatory angle to a neutral radius of the
substrate when the substrate is stationary.
9. The apparatus of claim 8 wherein the second oscillatory position
is at a second oscillatory angle to a neutral radius of the
substrate when the substrate is stationary.
10. The apparatus of claim 9 wherein the first oscillatory angle is
the same as the second oscillatory angle.
11. The apparatus of claim 9 wherein the frequency of oscillation
between the first and second oscillatory positions is varied.
12. The apparatus of claim 1 wherein the polishing head is adapted
to rock about an axis tangential to the substrate notch.
13. A system for polishing a notch in a substrate edge comprising:
a substrate support adapted to support a substrate; a polishing
head adapted to press a polishing tape against a notch in an edge
of the substrate; a controller adapted to oscillate the substrate
between at least first and second oscillatory positions while the
polishing head contacts the substrate notch and to control
polishing by the polishing head.
14. The system of claim 13 wherein the polishing head includes a
backing pad.
15. The system of claim 14, wherein the backing pad is adapted to
contact the substrate notch with the polishing tape.
16. The system of claim 15 further comprising a motor, wherein the
motor is adapted to advance the polishing tape, thereby creating
relative movement between the polishing tape and the substrate
notch.
17. The system of claim 13 wherein the first oscillatory position
is at a first oscillatory angle to a neutral radius of the
substrate when the substrate is stationary.
18. The system of claim 19 wherein the second oscillatory position
is at a second oscillatory angle to a neutral radius of the
substrate when the substrate is stationary.
19. The system of claim 13 wherein the substrate oscillates at a
first amplitude for a first period of time and at a second
amplitude for a second period of time.
20. A method for polishing a notch in a substrate edge comprising:
supporting a substrate, wherein an edge of the substrate includes a
notch; pressing a polishing head against a surface of the notch;
and oscillating the substrate between first and second oscillatory
positions while the polishing head is pressed against the
notch.
21. The method of claim 20 further comprising pressing a polishing
tape against the notch via the polishing head.
22. The method of claim 21 further comprising advancing the
polishing tape as the polishing tape is pressed against the
notch.
23. The method of claim 20 further comprising rocking the polishing
head about the notch.
24. The method of claim 20 further comprising conforming the
polishing head to the shape of the notch.
25. The method of claim 20, wherein the polishing head includes a
backing pad adapted to conform to the shape of the notch.
Description
[0001] The present application claims priority from U.S.
Provisional 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),
which is hereby incorporated by reference herein in its
entirety.
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/PPC/CMP/CKIM);
[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/PPC/CMP/CKIM);
[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); and
[0015] 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
[0016] The present invention relates generally to substrate
processing, and more particularly to methods and apparatus for
cleaning a notch in an edge of a substrate.
BACKGROUND OF THE INVENTION
[0017] Substrates are used in semi-conductor device manufacturing.
During processing, the notch and edge of a substrate may become
dirty, which may negatively affect the semi-conductor devices
formed on the substrate. Conventional systems may not be able to
effectively clean a substrate notch in a cost-effective amount of
time. Accordingly, improved methods and apparatus for cleaning or
polishing notches in the edges of substrates are desired.
SUMMARY OF THE INVENTION
[0018] In a first aspect of the invention, an apparatus for
polishing a notch in a substrate edge is provided. The apparatus
comprises a substrate support adapted to support a substrate; a
polishing head adapted to contact a notch in an edge of the
substrate; and a controller adapted to oscillate the substrate
between at least first and second oscillatory positions while the
polishing head contacts the substrate notch.
[0019] In another aspect of the invention, a system for polishing a
notch in a substrate edge is provided. The system comprises a
substrate support adapted to support a substrate; a polishing head
adapted to press a polishing tape against a notch in an edge of the
substrate; a controller adapted to oscillate the substrate between
at least first and second oscillatory positions while the polishing
head contacts the substrate notch to control polishing by the
polishing head.
[0020] In yet another aspect of the invention, a method for
polishing a notch in a substrate edge is provided. The method
comprises supporting a substrate, wherein an edge of the substrate
includes a notch; pressing a polishing head against a surface of
the notch; and oscillating the substrate between first and second
oscillatory positions while the polishing head is pressed against
the notch.
[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 DRAWINGS
[0022] FIG. 1 is a schematic plan view of an embodiment of a system
for polishing parts of a substrate, including major surfaces, edge,
bevel, and notch in accordance with the present invention.
[0023] FIG. 2 is a perspective view of an embodiment of a polishing
apparatus for polishing a substrate notch in accordance with the
present invention.
[0024] FIG. 3 is a perspective view of part of the embodiment of a
polishing apparatus for polishing a substrate notch, shown in FIG.
2.
[0025] FIG. 4 is a schematic illustration of part of an exemplary
substrate, including a substrate notch.
[0026] FIG. 5 is a schematic cross-sectional view of an embodiment
of a supporting backing pad for polishing a substrate notch in
accordance with the present invention.
[0027] FIG. 6 is a top plan view of an exemplary substrate.
[0028] FIG. 7 is a flow chart of a method for polishing a substrate
notch according to an embodiment of the present invention.
DETAILED DESCRIPTION
[0029] Substrates used in semiconductor device processing often
have films and/or surface defects which typically should be removed
prior to subsequent processing steps. In some cases, these films
and defects may occur on the edge of a substrate, including a notch
formed thereon.
[0030] One method of cleaning and polishing a substrate notch
includes applying an abrasive film or tape to the notch, and moving
the abrasive tape relative to the notch, while the substrate is
fixed in a particular position. The force, or pressure, applied to
the abrasive tape while contacting the notch, as well as the degree
of contact between the abrasive tape and the notch, may contribute
to polishing efficiency. Another factor that may contribute to
polishing efficiency is the degree of movement of the abrasive tape
relative to the substrate notch. In some embodiments, the relative
movement may be provided by advancing the abrasive tape over a
surface of the notch. However, the degree of relative movement
between the abrasive tape and the substrate notch may be increased
by moving the substrate as the abrasive tape is advanced over the
notch surface, thereby increasing the notch polishing efficiency
and the cost-effectiveness thereof.
[0031] The present invention provides apparatus and methods that
enhance contact between the polishing or abrasive tape and all
sections of a substrate notch region to efficiently and
cost-effectively remove thin films and surface defects from the
substrate notch. In one or more embodiments, a notch backing pad
may be provided. The notch backing pad may be adapted to press a
moving polishing tape against the substrate notch. In some
embodiments, the notch backing pad may include a protruding portion
that substantially conforms to the shape of the substrate notch.
The protruding portion may be made of an elastically deformable
material adapted to effectively conform the notch backing pad to
the shape of the notch (e.g., when pressed against the notch), and
to press the polishing tape into contact with all surfaces of the
notch. The notch backing pad may include slots to guide the
polishing tape over the notch backing pad.
[0032] In some embodiments, the substrate may be rotated and/or
oscillated about a center of rotation as the polishing tape is
advanced over the notch. The rotation and/or oscillation may
increase the degree of relative movement between the polishing tape
and the substrate notch, thereby increasing the polishing
efficiency and cost-effectiveness thereof.
[0033] FIG. 1 is a schematic plan view depicting an exemplary
embodiment of a substrate polishing system 100 according to the
present invention. The system 100 of FIG. 1 may be adapted to
polish a substrate 102, including, for example, a substrate edge
101 and/or notch 244 (shown in FIG. 3) positioned in the substrate
edge 101. In some embodiments, the notch 244 may be used to align
the substrate 102 in the system 100. The substrate 102 may also
include two major surfaces 103, (one of which is shown). Each major
surface 103 of the substrate 102 may include a device region (not
shown) upon which devices may be fabricated, and edge exclusion
regions (not shown) upon which device fabrication is not meant to
occur. (Typically however, only one of the two major surfaces 103
will include a device region and an edge exclusion region). The
edge exclusion regions or zones may serve as a buffer between the
device regions and the substrate edge 101. In an edge polishing
process, the substrate edge 101, including the notch 244, may be
polished to remove defects or contaminants, to reduce film
thickness and more generally to improve surface uniformity.
[0034] The system 100 of FIG. 1 includes three polishing heads 104
which, in turn, may each include a plurality of polishing apparatus
for cleaning and polishing the above-mentioned parts of the
substrate 102. Any number and type of polishing heads 104 may be
used in any practicable combination. Any number of heads 104 may be
used concurrently, individually, and/or in any sequence. The one or
more heads 104 may be disposed in different positions, and in
different orientations (e.g., aligned with the substrate edge or
notch, normal to the substrate edge or notch, angled relative to
the substrate edge or notch, etc.), to allow the one or more
polishing heads 104 (and backing pads and/or polishing tape
described further below) to polish different portions of the edge
and/or notch of the substrate 102. The substrate 102 may be
stationary or rotate as it is polished. The one or more heads 104
may be adapted to be oscillated or moved (e.g., angularly
translated about a tangential axis of the substrate 102 and/or
circumferentially translated relative to the substrate 102) around
or along the substrate edge 101 and/or notch 244 by any suitable
means so as to polish different portions of the substrate 102.
Different heads 104 may be used for different substrates 102,
different types of substrates 102, or different polishing
operations.
[0035] The system 100 may also include a programmed or user
operated controller 106. The controller 106 may direct the
operation and movement of the one or more heads 104, as well as the
other system components, as will be further described below.
[0036] FIG. 2 is a perspective view of an embodiment of a polishing
apparatus 200 for polishing a substrate notch 244 (shown in FIG.
3). The polishing apparatus 200 may include a substrate driver 210
(e.g., a servomotor, gear, belt, chain, etc.), which may be mounted
on a pedestal 212. A support 214 (e.g., a vacuum chuck) may be
coupled (e.g., rigidly) to a shaft (not shown) of the substrate
driver 210. The support 214 may support a substrate 216, for
example. The substrate driver 210 may rotate the substrate 216, via
the support 214, about a center 218 of the substrate 216 or another
suitable axis. The substrate driver 210 may be connected to a
substrate driver control unit (not shown), which may control the
angular displacement, angular velocity, and angular acceleration of
the substrate 216. The polishing apparatus 200 may further include
a polishing arm 220 aligned in the horizontal plane approximately
tangential to the edge 103 (shown in FIG. 1) of the substrate 216
and supported by a frame 224. In other embodiments, the polishing
arm 220 may be aligned differently, for example, vertically or at
an angle with respect to the horizontal plane. The polishing arm
220 may include a polishing head section 222. The polishing head
222 may include a notch backing pad 226, which may be moved toward
or away from the substrate 216 by an actuator (e.g., hydraulic
actuator, pneumatic actuator, servomotor, etc.) (not shown).
Polishing tape 228, may wrap around the polishing head 220, and
over the notch backing pad 226, and be tensioned between spools
230, 232. The spools 230, 232 may be driven by spool drivers 234,
236 (e.g., servomotors), respectively. The spool drivers 234, 236,
may be indexed to precisely control the amount of the polishing
tape 228 that is advanced over the polishing head 220 from, for
example, spool 230 to spool 232 in order to polish the notch 244 in
the substrate 216.
[0037] In one or more embodiments, the polishing tape 228 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 from about 0.5 microns
up to about 3 microns in size, although other sizes may be used.
Different widths of polishing tape 228 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 228 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
230, 232 may have a diameter of approximately 1 inch and be capable
of holding about 500 inches of polishing tape 228. Other spool
dimensions may be used. The spools 230, 232 may be constructed from
materials such as polyurethane, polyvinyl difluoride (PVDF), etc.
Other materials may also be used.
[0038] FIG. 3 is a perspective view of part of the embodiment of
the polishing apparatus 200 shown in FIG. 2 for polishing the
substrate notch 244. The polishing head 222, supported by the
polishing arm 220, may include the notch backing pad 226 and one or
more guide rollers 238, 240. In some embodiments, the polishing
tape 228 may wrap around the polishing head 222 by wrapping around
one of the guide rollers 238, the notch backing pad 226 and another
of the guide rollers 240. As described above, the polishing tape
228 may be tensioned between spool 230 and 232. In some embodiments
the notch backing pad 226 may include a protruding portion 242,
having a cross section similar in shape to the substrate notch 244.
The polishing tape 228 may be positioned to conform to the shape of
the protruding portion 242 of the notch backing pad 226 when
wrapped around the polishing head 220, and tensioned between the
spools 230, 232.
[0039] As described above, the notch backing pad 226 may be moved
toward, or away from, the substrate 216 by an actuator (not shown).
Any other suitable means to move the notch backing pad 226 may be
used. When the notch backing pad 226 is moved toward the substrate
216, the protruding portion 242 of the notch backing pad 226 may be
pressed into the substrate notch 244. As the protruding portion 242
is pressed into the notch 244, the section of polishing tape 228
conforming to the shape of the protruding portion 242 of the notch
backing pad 226 is also pressed into, and conforms to, the
substrate notch 244, and thereby contacts the entire substrate
notch 244 surface. As the polishing tape 228 may contact the entire
surface of the substrate notch 244, as the polishing tape 228 is
advanced, it may clean and polish the entire surface of the
substrate notch 244.
[0040] With reference to FIG. 4, a part of the substrate 216
including the notch 244 is schematically illustrated. The size of
the notch 244 is exaggerated for clarity purposes. The notch 244
may include one or more notch sides 400. The notch 244 may also
include one or more notch corners 402. Each notch corner 402 may be
positioned at the intersection of a notch side 400 and the outer
perimeter of the substrate 216. The notch 244 may further include a
notch center 404, positioned at the intersection of the one or more
notch sides 400. A notch depth 406 may be calculated as the length
or distance between the horizontal plane of the notch center 404
and the horizontal plane of the notch corners 402. In some
embodiments, for example, in the embodiment shown herein, the notch
244 may exhibit a large change in curvature as it is traced from
one notch corner 402 to another notch corner 402, via the notch
sides 400 and notch center 404. The change in curvature of the
notch 244 geometry may make it desirable to maintain consistent
contact between the polishing tape 228 and all regions (e.g., notch
sides 400, notch corners 402, and notch center 404) of the notch
244 during polishing, such that the entire notch 244 may be
polished/cleaned.
[0041] FIG. 5 is a schematic cross-sectional view of an exemplary
embodiment of the notch backing pad 226 adapted to polish the
substrate notch 244. As described above, the notch backing pad 226
may include the protruding portion 242, whose shape roughly
corresponds to the shape of the substrate notch 244. In some
embodiments, the protruding portion 242 may be made of a soft
conforming material, such as polyurethane, or any other suitable
material. In other embodiments, the protruding portion 242 may be
made of a rigid material. The rest of the notch backing pad 226 may
be made of soft, conforming materials, or rigid materials. The
notch backing pad 226 may also include one or more slots 246, 248.
The slots 246, 248 may guide the polishing tape 228 over the
protruding portion 242, as the polishing tape 228 is advanced and
contacts the substrate notch 244. When the protruding portion 242
of the notch backing pad 226 is pressed into the notch 244, the
protruding portion 242 may conform to the shape of the notch 244,
and thereby cause the polishing tape 228 to contact the notch sides
400, the notch corners 402 and the notch center 404 (FIG. 4).
[0042] Turning to FIG. 6, a top plan view of an exemplary
embodiment of substrate oscillating in the notch polishing
apparatus of the present invention. It should be noted that the
notch 244 shown herein is not drawn to scale, and is enlarged for
illustrative purposes. As described above with respect to FIGS. 1
and 2, the substrate 216 may be supported by the support 214, and
rotated and/or oscillated about the substrate center 218 by the
substrate driver 210. For example, the controller 106 (FIG. 1) or
another controller may cause the substrate driver 210 to rotate
back and forth so as to rotate (e.g., oscillate) the substrate 216
back and forth. To polish the substrate notch 244, the polishing
tape 228 may be advanced over the notch backing pad 226, as the
polishing tape 228 contacts the notch 244, via pressure from the
notch backing pad 226. The direction of polishing tape 228
advancement as the polishing tape 228 contacts the notch 244 may be
approximately perpendicular to a plane of rotation of the substrate
216, i.e., approximately normal to the figure. However, the
polishing tape 228 may be advanced at other angles with respect to
the plane of rotation of the substrate 216.
[0043] In some embodiments, as the polishing tape 228 is advanced,
the substrate 216 may be rotated or oscillated sinusoidally or
otherwise about its center 218. For example, the controller 106
(FIG. 1) may cause the substrate driver 210 to rotate back and
forth. In the exemplary embodiment shown herein, the substrate 216
is oscillated about its center of rotation 218. Radius R indicates
a direction in which the substrate notch 244 is aligned with, or
approximately centered with respect to, the polishing head 222 (not
shown in FIG. 6, shown in FIG. 2) and, specifically, the protruding
portion 242 of the notch backing pad 226 (see FIG. 5). As the
substrate 216 is oscillated, radius R may indicate a neutral
position or direction of the substrate 216, and radii R.sub.1 and
R.sub.2 may indicate limits of travel of the notch center 204
(shown in FIG. 4) as the substrate is oscillated through angles
.theta..sub.1 and .theta..sub.2, respectively. Dotted line 244a
indicates an outline of the notch 244 at one limit of travel
R.sub.1, and dotted line 244b indicates an outline of the notch 244
at another limit of travel R.sub.2. The angles of rotation
.theta..sub.1 and .theta..sub.2 of the substrate 216 may be set
approximately equal to one another, or they may be set different
from one another. Each angle .theta..sub.1, .theta..sub.2 may range
between approximately 0 degrees and approximately 1 degree during
polishing in some embodiments. Other angles may be used. A
frequency of oscillation of the substrate 216 between radii R.sub.1
and R.sub.2 may be varied, for example, from approximately 0
cycles/min to approximately 50,000 cycles/min during polishing, and
preferably from approximately 1000 cycles/min to approximately
50,000 cycles/min during polishing. Other and/or a constant number
of cycles per minute may be used.
[0044] The force or pressure at which the polishing tape 228 is
pressed against the notch 244, as well as the relative movement of
the polishing tape 228 and the notch 244 may account for the degree
and/or efficiency of polishing. The advancement of the polishing
tape 228, for example, in a direction perpendicular to the major
surface of the substrate 216, as it contacts the notch 244 may
provide relative movement between the polishing tape 228 and the
notch 244, thereby aiding in the polishing process. In addition,
oscillation of the substrate 216 about the substrate center 218
during the advancement of the polishing tape 228 may provide
further relative movement between the polishing tape 228 and a
surface of the notch 244, thereby aiding in the polishing process.
In some embodiments, the combination of substrate oscillation with
polishing tape advancement may result in more effective notch
polishing than the use of polishing tape advancement alone, as the
oscillation creates greater contact between the polishing tape 228
and the notch surfaces.
[0045] Turning to FIG. 7, an exemplary method 700 for cleaning and
polishing the notch 244 in the substrate 216 is depicted. In step
S702, the substrate 216 may be positioned and secured on the
support 214. Then, in step S704, the substrate 216 may be rotated
until the notch 244 is aligned with the polishing head 222, e.g.,
aligned with the protruding portion 242 of the notch backing pad
226. In step S706, the protruding portion 242 of the notch backing
pad 226 contacts the substrate notch 244, and presses the polishing
tape 228 against the notch 244. In step S708, the polishing tape
228 may be advanced by spool driver 234 or spool driver 236, e.g.,
either of spools 230, 232 may be used as a take-up spool or a
supply spool. In step S710, the substrate 216 may be oscillated
about its center 218 or another suitable point. This step may be
performed simultaneously with, before, or after step S708.
Advancement of the polishing tape 228 as it contacts the notch 244,
in combination with the oscillation of the substrate 216, removes
and eliminates films and imperfections on the notch 244 via
abrasion.
[0046] In addition, in step S712, the polishing head 222 may be
vertically rotated or rocked about the notch 244, e.g., the
polishing head 222 may rotate about an axis tangential to the
substrate 216 (and hence notch 244), as the polishing tape 228 is
advanced, in order to more effectively clean and polish parts of
the notch 244 adjacent to major surfaces 103 (shown in FIG. 1) of
the substrate 216. Step S712 may be performed simultaneously with,
before or after step S708 and/or S710. The speed, direction,
tension, pressing force, etc., of the polishing tape 228, the
rotational displacement, speed, and acceleration of the substrate
216, and the rotational displacement, speed, and acceleration of
the polishing head 222 about the substrate 216, may be adjustable,
via, for example, the controller 106 (FIG. 1). For instance, the
polishing tape 228 may be advanced at one speed for a certain
length, and then another speed for another length. In addition, the
polishing tape 228 may be at least one of translated and
oscillated, with constant or variable tensions and pressing forces.
Furthermore, the substrate 216 may be oscillated at a first
amplitude for a first period of time and a second amplitude for a
second period of time. Additionally or alternatively, the substrate
216 may alternate between time periods of oscillation and time
periods of simple or no rotation. Substrate oscillation may also be
employed during cleaning of an edge region of a substrate which
does not include a notch (e.g., using similar or other
oscillations).
[0047] The foregoing description discloses only exemplary
embodiments of the invention. Modification 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.
[0048] 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 claim.
* * * * *