U.S. patent application number 09/847964 was filed with the patent office on 2002-05-16 for semiconductor polishing pad.
Invention is credited to Acevedo, Marco A., Eppert, Stanley E. JR., Freeman, Peter W., Vo, Tuyen.
Application Number | 20020058468 09/847964 |
Document ID | / |
Family ID | 22746600 |
Filed Date | 2002-05-16 |
United States Patent
Application |
20020058468 |
Kind Code |
A1 |
Eppert, Stanley E. JR. ; et
al. |
May 16, 2002 |
Semiconductor polishing pad
Abstract
A belt has a polishing pad with one or more polishing pad
sections joined to the belt by an adhesive layer. A seam joint is
reinforced with caulking material. Edge portions of the seam joint
are beveled or dovetailed. Parallel stress relief grooves in the
upper surface of the polishing pad prevent delamination of the
polishing pad from the belt.
Inventors: |
Eppert, Stanley E. JR.;
(Wilmington, DE) ; Acevedo, Marco A.; (Mesa,
AZ) ; Freeman, Peter W.; (Bear, DE) ; Vo,
Tuyen; (Fremont, CA) |
Correspondence
Address: |
Rodel Holdings, Inc.
Suite 1300
1105 North Market Street
Wilmington
DE
19899
US
|
Family ID: |
22746600 |
Appl. No.: |
09/847964 |
Filed: |
May 3, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60201629 |
May 3, 2000 |
|
|
|
Current U.S.
Class: |
451/489 ;
156/345.13 |
Current CPC
Class: |
B24D 11/06 20130101;
B24B 21/04 20130101; B24B 37/26 20130101 |
Class at
Publication: |
451/489 ;
156/345.13 |
International
Class: |
B24D 017/00 |
Claims
What is claimed is:
1. A polishing pad adapted for mounting on a belt, characterised
by: a seam joint between opposed edge portions of the polishing
pad, and a caulking material in the seam joint bonding to the
opposed edge portions, which decreases the likelihood of
stretching, bunching up, and/or delaminating of the pad from the
belt.
2. The polishing pad according to claim 1, wherein the polishing
pad has one polishing pad section with a length that corresponds to
the outer circumference of the belt, and wherein the polishing pad
section has the opposed edge portions.
3. The polishing pad according to claim 1, wherein the polishing
pad has multiple polishing pad sections having the opposed edge
portions.
4. The polishing pad according to claim 1, wherein the seam joint
is provided with a channel.
5. The polishing pad and belt according to claim 1, wherein the
opposed polishing pad edge portions have contours forming a
channel.
6. The polishing pad according to claim 5, wherein the depth of the
channel is half the thickness of the polishing pad.
7. The polishing pad according to claim 5, wherein the channel has
a triangular shape.
8. The polishing pad according to claim 5, wherein the contours
have angled slopes.
9. The polishing pad according to claim 1, wherein the caulking
material is polyurethane.
10. The polishing pad according to claim 1, and further comprising:
adhesive laminating the polishing pad to a belt, and the caulking
material prevents the polishing pad from delaminating from the belt
as the pad and the belt rotate over rollers in a semiconductor
polishing fixture.
11. The polishing pad according to claim 1, wherein a polishing
surface of the polishing pad includes stress relief grooves
oriented transversely relative to a direction of rotation of the
polishing pad in a polishing pad fixture.
12. A reinforced semiconductor polishing pad and belt comprising: a
belt; a polishing pad in adhesive connection with the belt, wherein
the polishing pad includes a polishing surface that is operative to
polish and planarize a semiconductor substrate, and wherein the
polishing pad includes at least one seam joint between two opposed
polishing pad edge portions, and wherein each of the opposed
polishing pad edge portions are cooperatively contoured in
overlapping relation.
13. The reinforced semiconductor polishing pad and belt according
to claim 12, wherein the polishing pad is comprised of one
polishing pad section with a length that corresponds to the outer
circumference of the belt, wherein the opposed polishing pad edge
portions correspond to the ends of the one polishing pad
section.
14. The reinforced semiconductor polishing pad and belt according
to claim 12, wherein the polishing pad is comprised of at least two
polishing pad sections, wherein the opposed polishing pad edge
portions correspond to adjacent ends of the two polishing pad
sections.
15. The reinforced semiconductor polishing pad and belt according
to claim 12, wherein the opposed polishing pad edge portions are
cooperatively beveled.
16. The reinforced semiconductor polishing pad and belt according
to claim 12, wherein the opposed polishing pad edge portions are
cooperatively dove-tailed.
17. The reinforced semiconductor polishing pad and belt according
to claim 12, wherein the belt is comprised of a stainless steel
mesh.
18. The reinforced semiconductor polishing pad and belt according
to claim 12, wherein seam joint is orientated in a generally
transverse direction with respect to the direction of rotation of
the belt in a polishing pad fixture.
19. The reinforced semiconductor polishing pad and belt according
to claim 12, wherein the polishing surface includes a plurality of
parallel stress relief grooves in an upper surface of the polishing
pad, wherein the parallel stress relief grooves are oriented in a
generally transverse direction with respect to the direction of
rotation of the belt in a polishing pad fixture.
20. A delamination resistant semiconductor polishing pad and belt
characterised by: a belt; and a polishing pad in adhesive
connection with the belt, wherein the polishing pad includes a
polishing surface that is operative to polish and planarize a
semiconductor substrate, wherein the polishing surface includes a
plurality of parallel stress relief grooves therein.
21. The delamination resistant semiconductor polishing pad and belt
according to claim 20, wherein the parallel stress relief grooves
are oriented in a generally transverse direction with respect to
the direction of rotation of the belt across at least one belt
roller 16 of a polishing pad fixture.
22. The delamination resistant semiconductor polishing pad and belt
according to claim 21, wherein the parallel stress relief grooves
each have a depth of generally between 5 and 45 mils.
23. The delamination resistant semiconductor polishing pad and belt
according to claim 22, wherein the parallel stress relief grooves
each have a width of generally between 5 and 60 mils.
24. The delamination resistant semiconductor polishing pad and belt
according to claim 23, wherein the distance between parallel stress
relief grooves along the upper surface of the polishing pad is
generally between 50 and 500 mils.
25. The delamination resistant semiconductor polishing pad and belt
according to claim 21, wherein the stress relief grooves have a
generally rectangular cross-sectional shape.
26. The delamination resistant semiconductor polishing pad and belt
according to claim 20, wherein the stress relief grooves span the
width of the polishing pad.
Description
CROSS REFERENCE TO RELATED APPLICATION
[0001] This application claims the benefit of provisional
application serial No. 60/201,629 filed May 3, 2000.
FIELD OF THE INVENTION
[0002] This invention relates to a polishing pad and belt for
polishing and planarizing semiconductor substrate surfaces.
DISCUSSION OF RELATED ART
[0003] According to U.S. Pat. No. 5,593,344, a known polishing
fixture includes a continuous belt, a polishing pad adhered to the
belt, and multiple rollers over which the belt revolves in a
continuous belt movement. The polishing pad is comprised of a
single piece pad or, alternatively, multiple, individual pad
sections that are positioned adjacent to one another across an
outer surface of the belt. As the belt revolves, the polishing pad
moves to polish and planarize one or more semiconductor wafers that
are held against the polishing pad. Unfortunately as the belt
revolves over the curved surface on each the rollers, each pad
section bends to correspond to the curvature of the belt rollers.
Repeated bending of the pad sections places a significant amount of
stress on the pad. This stress results in stretching and bunching
up of an adhesive layer between the belt and each of the pad
sections, which can lead to delamination of the pad sections from
the belt. Consequently, a need exists for a polishing belt with a
polishing pad that is less likely to stretch, bunch up, and/or
delaminate when curved around rollers or other non-planar features
of a semiconductor polishing fixture.
SUMMARY OF THE INVENTION
[0004] According to the invention, a polishing pad adapted for
mounting on a belt is provided with a seam joint between opposed
edge portions of the pad, which decreases the likelihood of
stretching, bunching up, and/or delaminating of an adhesive layer
between the belt and the pad.
[0005] Embodiments of the invention will now be described by way of
example with reference to the accompanying drawings, according to
which:
[0006] FIG. 1 is a perspective view representative of a polishing
belt fixture that includes a known polishing pad;
[0007] FIG. 2 is a top plan view of a known polishing pad adhered
to a polishing belt;
[0008] FIG. 3 is a side plan view of a known polishing pad adhered
to a polishing belt.
[0009] FIG. 4 is a side plan view of a known polishing pad of which
polishing pad sections have become delaminated from the belt;
[0010] FIG. 5 is a side plan view of an exemplary polishing pad
fixture that includes an exemplary polishing pad and belt;
[0011] FIGS. 6-8 are respective side plan views of reinforced seam
joints between pad sections or between pad ends of exemplary
embodiments of the polishing pad and belt of the present
invention.
[0012] FIGS. 9 and 10 are respective side plan views of alternative
configurations of seam joints for exemplary embodiments of the
polishing pad;
[0013] FIG. 11 is representative of a side plan view of an
exemplary embodiment of a polishing pad that includes parallel
stress relief grooves.
DETAILED DESCRIPTION
[0014] FIG. 1 discoses that integrated circuits are typically
fabricated from semiconductor substrates or semiconductor wafers
18. The surfaces of semiconductor wafers 18 are finely polished and
planarized using chemical mechanical polishing (CMP) processes.
Many of these polishing CMP processes use a polishing fixture 10
that includes a polishing belt 14. FIG. 1 discloses a polishing
fixture 10 that includes a polishing belt 14 that is configured to
revolve over a plurality of belt rollers 16. The belt 14 includes a
polishing pad 12 adhered thereto. The polishing pad 12 has
individual pad sections 20 that are adjacent to each other across
the outer surface of the belt 14. As the belt 14 moves, each of the
sections 20 is operative to polish and planarize one or more
semiconductor wafers 18 that are held adjacent the polishing pad
12.
[0015] FIG. 2 discloses a known polishing belt 14 with a polishing
pad 12 adhered thereto. The polishing pad 12 includes independent
sections 20. FIG. 3 discloses that each prior art polishing pad
section 20 includes a corresponding independent adhesive layer 32
that is operative to adhere the polishing pad section 20 to the
surface of the belt 14. Unfortunately the revolving configuration
of the belt 14 over belt rollers 16 requires that each of the pad
sections 20 periodically bend to correspond to the curvature of the
belt rollers 16. Bending of the pad 12 and of the pad sections 20
places a significant amount of stress on the pad 12. This stress
results in stretching and bunching up of the adhesive layers 32
between the pad 12 and the belt 14 which can lead to delamination
of the sections 20 of the pad 12 from the belt 14.
[0016] FIG. 4 discloses the belt 14 curving around a roller 16,
which has caused delamination. The opposed edge portions 38 and 40
of the sections 20 have lost their adhesive connection with the
belt 14. Such delamination can significantly reduce the expected
operational lifetime of the polishing pad 12 and can degrade the
polishing performance of the pad 12. Consequently, there exists a
need for an improved polishing belt 14 with a polishing pad 12 that
is less likely to stretch, bunch up, and/or delaminate when curved
around rollers 16 or other non-planar features of a semiconductor
polishing fixture 10.
[0017] The invention provides a polishing pad 12 and belt 14 for
polishing semiconductor wafers 18, which includes features for
maintaining a strong bond with the polishing pad 12 and belt 14.
Further, features of the invention are operative to reduce the
likelihood of stretching the adhesive layer 32 between the
polishing pad 12 and the belt 14. Further, features of the
invention reduce the likelihood of bunching up of an adhesive layer
32 between the polishing pad 12 and the belt 14. Further, features
of the invention reduce the likelihood of delamination of portions
of the polishing pad 12 from the belt 14. Further, features of the
invention maintain adhesion between the polishing pad 12 and the
belt 14 as the belt 14 and polishing pad 12 bend around a belt
roller 16.
[0018] An exemplary embodiment of the invention includes, a
semiconductor polishing belt 14 that includes a delamination
resistant polishing pad 12 bonded thereto. In one exemplary
embodiment the polishing pad 12 includes a plurality of adjacent
polishing pad sections 20 that are bonded to the outer surface of
the belt 14. In an alternative exemplary embodiment the polishing
pad 12 is comprised of a single polishing pad section 20 that is
bonded to the outer surface of the belt 14. Such a single polishing
pad section 20 has a length that corresponds to the outer
circumference of the belt 14.
[0019] In another exemplary embodiment the belt 14 is comprised of
a stainless steel mesh in the shape of a continuous loop that is
operatively flexible for traveling around rollers 16 of a polishing
pad fixture. The polishing pad sections 20 in the exemplary
embodiment are comprised of a flexible and elastic polymer such as
a polyurethane. The polishing pad sections 20 are machine laminated
to the outer surface of the belt 14 with an adhesive layer 32
comprised of an adhesive such as a flexible double-sided pressure
sensitive or contact adhesive. In the exemplary embodiment with
multiple pad sections 20 bonded to the belt 14, the seam joints 56
between adjacent pad sections 20, include features which decrease
the likelihood of the adhesive layer 32 stretching, bunching up,
and/or delaminating. In the exemplary embodiment of the present
invention with a single polishing pad 12 bonded to the belt 14, the
seam joint 56 between adjacent ends of the pad 12, include features
which decrease the likelihood of the adhesive layer 32 stretching,
bunching up, and/or delaminating
[0020] In one exemplary embodiment these features include a
polishing pad 12 with adjacent edges of pad sections 20 or pad ends
that are cooperatively beveled or dovetailed to interlock and/or
overlap with each other. In another exemplary embodiment the seam
joints 56 between adjacent pad sections 20 or pad ends are
reinforced with a caulking material such as an elastic polymer. By
reinforcing the seam joints 56, with interlocking or overlapping
seams and/or caulking the present exemplary invention is operative
to prevent the adhesive layer 32 from stretching and/or
delaminating from the belt 14 as the polishing pad 12 of the belt
14 curves around belt rollers 16 or other non-planar features of a
polishing fixture 10.
[0021] In other exemplary embodiments of the present invention, the
polishing pad 12 includes a plurality of parallel grooves spaced
across the width of the pad 12 in a transverse direction with
respect to the direction of movement of the polishing belt 14. The
grooves are operative to further relieve stress on the polishing
pad 12 and minimize the occurrence of pad 12 delamination as the
polishing pad 12 bends responsive to the curvature of a belt roller
16.
[0022] Referring now to the drawings and particularly to FIG. 5,
there is shown therein a a side plan view representative of an
exemplary semiconductor polishing fixture 10 that includes an
exemplary polishing pad 12 and belt 14 of the present invention.
This described polishing fixture 10 is representative of a
polishing pad apparatus, which includes two belt rollers 16.
However, alternative exemplary embodiments of the pad 12 and belt
14 may be used with other polishing fixtures with a plurality of
belt rollers 16 of various sizes, configurations, and orientations,
including the polishing fixture 10 shown in FIG. 1.
[0023] The polishing fixture 10 further includes a semiconductor
support 208, that is operative to place a semiconductor wafer 18
adjacent the polishing pad 12 and belt 14 of the present invention.
The exemplary polishing fixture 10 further includes a base 212 on
the opposite side of the pad 12 and belt 14 as the semiconductor
wafer 18. The base 212 is operative to prevent the relatively
planer surface of the pad 12 and belt 14 that is adjacent the
semiconductor wafer 18 from being deformed by the downward force of
the semiconductor support 208.
[0024] The exemplary embodiment of the polishing pad 12 and belt 14
for use with the polishing fixture 10 has an inner circumference of
between 90 and 110 inches. The exemplary width of the belt 14 is
between 20 and 40 inches. However, it is to be understood that
alternative embodiments of the pad 12 and belt 14 may have other
sizes based on the relative dimensions of the polishing fixture 10
that the pad 12 and belt 14 is installed thereon. For example the
exemplary polishing fixture 10 is shown with one semiconductor
support 208; however, alternative embodiments of the exemplary pad
12 and belt 14 may have sufficient width and length to be mounted
on a polishing fixture 10 that is operative to simultaneously
polish a plurality of semiconductor wafers 18.
[0025] FIG. 6 shows an exemplary embodiment of a polishing pad 12.
The polishing pad 12 includes pad portions 20 that are adhesively
bonded to a belt 14. In one exemplary embodiment the pad portions
20 are representative of discrete pad sections 20 that are placed
adjacent to one another along the outer surface of the belt 14.
Such pad sections 20 have lengths between 20 and 40 inches. In
another exemplary embodiment the pad portions 20 are representative
of opposite ends of a single polishing pad section 20 that is
bonded to the outer surface of the belt 14. Such a single polishing
pad section 20 has a length that corresponds to the outer
circumference of the belt 14.
[0026] The exemplary belt 14 is constructed of a flexible stainless
steel mesh that is operative to rotate about the belt rollers 16 at
a rate of between 400 and 1000 linear feet per minute. However,
alternative embodiments of the belt 14 may be comprised of other
flexible materials that are resistant to stretching. The exemplary
polishing pad 12 is comprised of a polyurethane, however,
alternative embodiments of the polishing pad 12 may be comprised of
other elastic polymer materials.
[0027] In the exemplary embodiment of the present invention a seam
joint 56 between the polishing pad portions 20 is reinforced with a
caulking material 58. The caulking material 58 is operative to
create a flexible bond between polishing pad portions 20, which
reinforces the seam joint 56. In the exemplary embodiment the
caulking material 58 is comprised of an elastic polymer such as
polyurethane or a uv-urethane. However, it is to be understood that
the present invention encompasses any flexible caulking material 58
that is operative to bind pad portions 52 and 54 of the polishing
pad 12.
[0028] By caulking the seam joints 56 between two or more polishing
pad sections 20, the polishing pad 12 may be manufactured as a
continuous sheet which subsequently is bonded to the belt 14,
rather than bonding multiple independent pad sections 20 to the
belt 14 as is done in the prior art. In one exemplary embodiment
the polishing pad 12 is machine laminated with an adhesive layer 32
that spans two or more pad sections 20 of the polishing pad 12. The
adhesive layer 32 is comprised of a flexible double sided pressure
sensitive or contact adhesive that is operative to bond the
polishing pad 12 to the belt 14.
[0029] To provide sufficient surface area for the caulking material
58 to reinforce the seam joint 56, the pad edge portions 40 and 38
are manufactured with contours which provide a channel 68 for
receiving the caulking material 58. As shown in FIG. 6, one
exemplary embodiment of the present invention includes a channel 68
that is rectangular in shape. In this described exemplary
embodiment the width of the rectangular channel 68 is between 30
and 100 mils. Also in this described exemplary embodiment the depth
of the channel 68 is between 20 and 30 mils, which is generally
half the thickness of the pad 12. However, it is to be understood
that the present invention encompasses any suitable dimensions for
the channel 68 that are operative to provide sufficient surface
area for the caulking material 58 to reinforce the seam joint
56.
[0030] FIG. 7 shows an alternative exemplary embodiment of a
polishing pad 12 with pad edge portions 38 and 40 that are
partially beveled or angled. These exemplary contours of the pad
edge portions 38 and 40 form a triangular shaped channel 68 between
the upper surface 81 of the polishing pad 12 and the adhesive layer
32, which is operative to receive a caulking material 58 for
reinforcing seam joint 56. FIG. 8 shows another alternative
exemplary embodiment of a polishing pad 12 with pad edge portions
38 and 40 that are beveled or angled between the upper surface 81
of the polishing pad 12 and the adhesive layer 32.
[0031] Although rectangular and triangular channels 68 have been
described, it is to be understood that the present invention
encompasses any other shape or contour of channels 68 between pad
sections 20 which are operative to receive a caulking material 58
for reinforcing the section joints of polishing pads 12.
Alternative embodiments of the present invention may have channels
68 with other shapes and contours including convex and concave
curvatures, or any other shape that is operative to provide
sufficient surface area for a caulking material 58 to provide a
strong and flexible bond between pad edge portions 38 and 40 of a
seam joint 56.
[0032] For the exemplary embodiment of the polishing pad 12 that is
comprised of multiple polishing pad sections 20, each of the seam
joints 56 between polishing pad sections 20 may be reinforced as
previously described. For the exemplary polishing pad 12 that is
comprised of a single polishing pad section 20 bonded to the outer
circumference of the belt 14, the seam joint 56 between the opposed
ends of the polishing pad 12 may be reinforced as previously
described.
[0033] FIGS. 9 and 10 show alternative exemplary embodiments of a
reinforced polishing pad 12. In these exemplary embodiments, the
polishing pad 12 includes pad edge portions 38 and 40 that are
cooperatively contoured to mate in an interlocking and/or
overlapping relation with each other. For example in FIG. 9,
polishing pad 12 includes two pad portions 20 with corresponding
pad edge portions 38 and 40 which are cooperatively beveled or
angled to interlock or overlap. Such an exemplary configuration is
operative to reinforce the seam joint 56 between pad portions 20
and prevent the polishing pad 12 from delaminating from the belt
14.
[0034] FIG. 10 is representative of another exemplary embodiment of
a polishing pad 12 with pad edge portions 38 and 40 which are
cooperatively dovetailed. Each of these described exemplary
interlocking and/or overlapping features of the present invention
are operative to reinforce the seam joints 56 between adjacent pad
sections 20 or pad ends which minimizes the stretching, bunching up
and delamination of the polishing pad 12.
[0035] In these described exemplary interlocking and/or overlapping
seam joint 56 embodiments an adhesive layer 32 may not only be used
to bond the polishing pad 12 to the belt 14, but may further be
applied between adjacent pad edge portions 38 and 40 of the seam
joints 56. Also as previously described a caulking material 58
comprised of an elastic polymer such as a polyurethane for example
may also be applied between the adjacent pad edge portions 38 and
40 of each interlocking and/or overlapping seam joint 56. In
addition, the present invention further comprises other
configurations and contours of interlocking and/or overlapping edge
portions 38 and 40 including cooperatively concave and convex
curved contours and shapes.
[0036] FIG. 11 is representative of another exemplary embodiment of
a polishing pad 12 bonded to a belt 14 of the present invention.
Here the polishing pad 12 includes a polishing layer 118 with a
plurality of parallel grooves 122 in an upper surface 124 of the
polishing layer 118. As with the previously described embodiments,
the polishing pad 12 includes an adhesive layer 32 that is
operative to bond the polishing pad 12 to a belt 14. In the
exemplary embodiment each of the grooves 122 are orientated
transversely with respect to the direction of movement 130 of the
belt 14. However alternative exemplary embodiments of the polishing
pad 12 may include grooves that are orientated along the surface
124 of the polishing pad 12 at other angles. As the polishing pad
12 curves around a belt roller 16, the grooves 122 enable the
polishing pad 12 to relieve stresses on the adhesive bond between
the polishing pad 12 and belt 14. Relief of this stress minimizes
the stretching, bunching up and delamination of the adhesive layer
32 that occurs in prior art designs.
[0037] In the exemplary embodiment the grooves range between about
5 and 45 mils in depth. The width of the grooves range between
about 5 and 60 mils and each groove is spaced every 50 to 500 mils
along the top surface 124 of the polishing pad 12. In this
described exemplary embodiment the grooves have planar vertical
side walls that are normal to the top surface of the pad 12.
However, alternative embodiments may have angled and/or curved
walls depending on the dimensions of the pad 12 and the expected
amount of curvature that the pad 12 will undergo when moving over a
belt roller 16.
[0038] Although embodiments of the invention have been described,
other embodiments and modifications of the invention are intended
to be covered by the spirit and scope of the appended claims.
* * * * *