U.S. patent application number 13/113655 was filed with the patent office on 2012-11-29 for polishing pad with homogeneous body having discrete protrusions thereon.
Invention is credited to William C. Allison, Rajeev Bajaj, Richard Frentzel, Ping Huang, Robert Kerprich, Diane Scott.
Application Number | 20120302148 13/113655 |
Document ID | / |
Family ID | 46147792 |
Filed Date | 2012-11-29 |
United States Patent
Application |
20120302148 |
Kind Code |
A1 |
Bajaj; Rajeev ; et
al. |
November 29, 2012 |
POLISHING PAD WITH HOMOGENEOUS BODY HAVING DISCRETE PROTRUSIONS
THEREON
Abstract
Polishing pads with homogeneous bodies having discrete
protrusions thereon are described. In an example, a polishing pad
for polishing a substrate includes a homogeneous body having a
polishing side and a back side. The homogeneous body is composed of
a material having a first hardness. A plurality of discrete
protrusions is disposed on and covalently bonded with the polishing
side of the homogeneous body. The plurality of discrete protrusions
is composed of a material having a second hardness different from
the first hardness. Methods of fabricating polishing pads with
homogeneous bodies having discrete protrusions thereon are also
described.
Inventors: |
Bajaj; Rajeev; (Fremont,
CA) ; Huang; Ping; (Eden Prairie, MN) ;
Kerprich; Robert; (Portland, OR) ; Allison; William
C.; (Beaverton, OR) ; Frentzel; Richard;
(Murrieta, CA) ; Scott; Diane; (Portland,
OR) |
Family ID: |
46147792 |
Appl. No.: |
13/113655 |
Filed: |
May 23, 2011 |
Current U.S.
Class: |
451/527 ;
264/255; 264/45.3 |
Current CPC
Class: |
B24B 37/24 20130101;
B29L 2009/00 20130101; B24D 18/0009 20130101; B24B 37/205 20130101;
B29L 2031/736 20130101; B24B 37/22 20130101; B29C 39/123 20130101;
B24B 37/26 20130101; B29K 2075/00 20130101 |
Class at
Publication: |
451/527 ;
264/255; 264/45.3 |
International
Class: |
B24D 11/00 20060101
B24D011/00; B29C 44/12 20060101 B29C044/12; B29C 39/12 20060101
B29C039/12 |
Claims
1. A polishing pad for polishing a substrate, the polishing pad
comprising: a homogeneous body having a polishing side and a back
side, the homogeneous body comprising a material having a first
hardness; and a plurality of discrete protrusions disposed on and
covalently bonded with the polishing side of the homogeneous body,
the plurality of discrete protrusions comprising a material having
a second hardness different from the first hardness.
2. The polishing pad of claim 1, wherein the polishing side of the
homogeneous body is substantially flat and is exposed between the
plurality of discrete protrusions.
3. The polishing pad of claim 1, wherein the homogeneous body is a
molded homogeneous body, and wherein the plurality of discrete
protrusions is a plurality of molded protrusions.
4. The polishing pad of claim 1, wherein the material of the
homogeneous body comprises a first thermoset polyurethane material,
and the material of the plurality of discrete protrusions comprises
a second, different, thermoset polyurethane material.
5. The polishing pad of claim 1, wherein the first hardness of the
material of the homogeneous body is less than the second hardness
of the material of the plurality of discrete protrusions.
6. The polishing pad of claim 5, wherein the first hardness is less
than approximately 40 Shore D, and the second hardness is greater
than approximately 30 Shore D.
7. The polishing pad of claim 6, wherein the first hardness is less
than approximately 25 Shore D, and the second hardness is greater
than approximately 40 Shore D.
8. The polishing pad of claim 1, wherein the first hardness of the
material of the homogeneous body is greater than the second
hardness of the material of the plurality of discrete
protrusions.
9. The polishing pad of claim 8, wherein the second hardness is
less than approximately 40 Shore D, and the first hardness is
greater than approximately 30 Shore D.
10. The polishing pad of claim 9, wherein the second hardness is
less than approximately 25 Shore D, and the first hardness is
greater than approximately 40 Shore D.
11. The polishing pad of claim 1, wherein the homogeneous body is
substantially circular, and one or more of the plurality of
discrete protrusions is a partial circumferential protrusion or an
arc-shaped protrusion.
12. The polishing pad of claim 1, wherein the plurality of discrete
protrusions comprises a plurality of tiles selected from the group
consisting of circular tiles, oval tiles, square tiles, hexagonal
tiles, and rectangular tiles.
13. The polishing pad of claim 1, wherein each of the plurality of
discrete protrusions has, in a global plane of the polishing side
of the homogeneous body, a shortest dimension approximately in the
range of 5-50 millimeters.
14. The polishing pad of claim 1, further comprising: a detection
region disposed in the back side of the homogeneous body.
15. The polishing pad of claim 1, further comprising: a local area
transparency (LAT) region disposed in the homogeneous body.
16. A polishing pad for polishing a substrate, the polishing pad
comprising: a homogeneous body having a polishing side and a back
side, the homogeneous body comprising a material having a first
hardness, and the polishing side comprising a plurality of
protrusions having a pattern; a plurality of discrete protrusions
disposed on and aligned with the plurality of protrusions of the
polishing side of the homogeneous body, the plurality of discrete
protrusions comprising a material having a second hardness
different from the first hardness, and the plurality of discrete
protrusions having the pattern; and a fill layer disposed on the
homogeneous body, around the plurality of protrusions of the
polishing side of the homogeneous body, the fill layer comprising
the material of the plurality of discrete protrusions.
17. The polishing pad of claim 16, wherein the fill layer is
discontinuous with the plurality of discrete protrusions.
18. The polishing pad of claim 16, wherein both the fill layer and
the plurality of discrete protrusions are covalently bonded with
the homogeneous body.
19. The polishing pad of claim 16, wherein the homogeneous body is
a molded homogeneous body, wherein the plurality of discrete
protrusions is a plurality of molded protrusions, and wherein the
fill layer is a molded fill layer.
20. The polishing pad of claim 16, wherein the material of the
homogeneous body comprises a first thermoset polyurethane material,
and the material of the plurality of discrete protrusions and the
fill layer comprises a second, different, thermoset polyurethane
material.
21. The polishing pad of claim 16, wherein the first hardness of
the material of the homogeneous body is less than the second
hardness of the material of the plurality of discrete protrusions
and the fill layer.
22. The polishing pad of claim 21, wherein the first hardness is
less than approximately 40 Shore D, and the second hardness is
greater than approximately 30 Shore D.
23. The polishing pad of claim 22, wherein the first hardness is
less than approximately 25 Shore D, and the second hardness is
greater than approximately 40 Shore D.
24. The polishing pad of claim 16, wherein the first hardness of
the material of the homogeneous body is greater than the second
hardness of the material of the plurality of discrete protrusions
and the fill layer.
25. The polishing pad of claim 24, wherein the second hardness is
less than approximately 40 Shore D, and the first hardness is
greater than approximately 30 Shore D.
26. The polishing pad of claim 25, wherein the second hardness is
less than approximately 25 Shore D, and the first hardness is
greater than approximately 40 Shore D.
27. The polishing pad of claim 16, wherein the homogeneous body is
substantially circular, and one or more of the plurality of
discrete protrusions is a partial circumferential protrusion or an
arc-shaped protrusion.
28. The polishing pad of claim 16, wherein the plurality of
discrete protrusions comprises a plurality of tiles selected from
the group consisting of circular tiles, oval tiles, square tiles,
hexagonal tiles, and rectangular tiles.
29. The polishing pad of claim 16, wherein each of the plurality of
discrete protrusions has, in a global plane of the polishing side
of the homogeneous body, a shortest dimension approximately in the
range of 5-50 millimeters.
30. The polishing pad of claim 16, further comprising: a detection
region disposed in the back side of the homogeneous body.
31. The polishing pad of claim 16, further comprising: a local area
transparency (LAT) region disposed in the homogeneous body.
32. A method of fabricating a polishing pad for polishing a
substrate, the method comprising: mixing a first set of
polymerizable materials to form a first mixture in the base of a
formation mold; at least partially curing the first mixture to form
a molded homogeneous body having a polishing side and a back side;
mixing a second set of polymerizable materials to form a second
mixture on the molded homogeneous body; placing a lid of the
formation mold into the second mixture, the lid having disposed
thereon a pattern of grooves; and, with the lid placed in the
second mixture, at least partially curing the second mixture to
form a plurality of discrete protrusions disposed on the polishing
side of the molded homogeneous body, the plurality of discrete
protrusions having a pattern corresponding to the pattern of
grooves of the lid.
33. The method of claim 32, further comprising: subsequent to
mixing the first set of polymerizable materials to form the first
mixture but prior to mixing the second set of polymerizable
materials to form the second mixture, placing the lid of the
formation mold into the first mixture and, with the lid placed in
the first mixture, performing the at least partially curing the
first mixture to form the molded homogeneous body with the
polishing side comprising a plurality of protrusions having a
pattern corresponding to the pattern of grooves of the lid, wherein
the plurality of discrete protrusions is formed on and aligned with
the plurality of protrusions of the polishing side of the molded
homogeneous body.
34. The method of claim 33, wherein forming the second mixture on
the molded homogeneous body comprises forming an amount of the
second mixture sufficiently large to form a fill layer disposed on
the molded homogeneous body, around the plurality of protrusions of
the polishing side of the molded homogeneous body, and wherein the
amount of the second mixture is sufficiently small to form the fill
layer discontinuous with the plurality of discrete protrusions
formed from the second mixture.
35. The method of claim 32, wherein the first set of polymerizable
materials comprises a first pre-polymer and a first curative, and
the second set of polymerizable materials comprises a second
pre-polymer and a second curative.
36. The method of claim 32, wherein the polishing side of the
molded homogeneous body is substantially flat and is exposed
between the plurality of discrete protrusions.
37. The method of claim 32, wherein the second mixture is different
from the first mixture, and wherein, upon fully curing the first
and second mixtures, the hardness of the plurality of discrete
protrusions is different from the hardness of the molded
homogeneous body.
38. The method of claim 32, wherein at least partially curing the
second mixture comprises covalently boding the plurality of
discrete protrusions with the molded homogeneous body.
39. The method of claim 32, wherein forming the molded homogeneous
body comprises forming a first thermoset polyurethane material, and
forming the plurality of discrete protrusions comprises forming a
second, different, thermoset polyurethane material.
40. The method of claim 32, wherein the mixing of the second set of
polymerizable materials further comprises adding a plurality of
porogens to the second set of polymerizable materials to form a
plurality of closed cell pores in the plurality of discrete
protrusions, each closed cell pore having a physical shell.
41. The method of claim 32, wherein the mixing of the second set of
polymerizable materials further comprises injecting a gas into the
second set of polymerizable materials, or into a product formed
there from, to form a plurality of closed cell pores in the
plurality of discrete protrusions, each closed cell pore having no
physical shell.
42. The method of claim 32, wherein the mixing of the second set of
polymerizable materials further comprises adding an opacifying
particle filler to the second set of polymerizable materials to
form an opaque plurality of discrete protrusions.
43. The method of claim 32, further comprising: further curing the
plurality of discrete protrusions and the molded homogeneous body
in an oven.
44. The method of claim 35, wherein mixing the first pre-polymer
and the first curative to form the first mixture comprises
degassing the first mixture, and wherein mixing the second
pre-polymer and the second curative to form the second mixture
comprises degassing the second mixture.
Description
TECHNICAL FIELD
[0001] Embodiments of the present invention are in the field of
chemical mechanical polishing (CMP) and, in particular, polishing
pads with homogeneous bodies having discrete protrusions
thereon.
BACKGROUND
[0002] Chemical-mechanical planarization or chemical-mechanical
polishing, commonly abbreviated CMP, is a technique used in
semiconductor fabrication for planarizing a semiconductor wafer or
other substrate.
[0003] The process uses an abrasive and corrosive chemical slurry
(commonly a colloid) in conjunction with a polishing pad and
retaining ring, typically of a greater diameter than the wafer. The
polishing pad and wafer are pressed together by a dynamic polishing
head and held in place by a plastic retaining ring. The dynamic
polishing head is rotated during polishing. This approach aids in
removal of material and tends to even out any irregular topography,
making the wafer flat or planar. This may be necessary in order to
set up the wafer for the formation of additional circuit elements.
For example, this might be necessary in order to bring the entire
surface within the depth of field of a photolithography system, or
to selectively remove material based on its position. Typical
depth-of-field requirements are down to Angstrom levels for the
latest sub-50 nanometer technology nodes.
[0004] The process of material removal is not simply that of
abrasive scraping, like sandpaper on wood. The chemicals in the
slurry also react with and/or weaken the material to be removed.
The abrasive accelerates this weakening process and the polishing
pad helps to wipe the reacted materials from the surface. In
addition to advances in slurry technology, the polishing pad plays
a significant role in increasingly complex CMP operations.
[0005] However, additional improvements are needed in the evolution
of CMP pad technology.
SUMMARY
[0006] Embodiments of the present invention include polishing pads
with homogeneous bodies having discrete protrusions thereon.
[0007] In an embodiment, a polishing pad for polishing a substrate
includes a homogeneous body having a polishing side and a back
side. The homogeneous body is composed of a material having a first
hardness. A plurality of discrete protrusions is disposed on and
covalently bonded with the polishing side of the homogeneous body.
The plurality of discrete protrusions is composed of a material
having a second hardness different from the first hardness.
[0008] In another embodiment, a polishing pad for polishing a
substrate includes a homogeneous body having a polishing side and a
back side. The homogeneous body is composed of a material having a
first hardness. The polishing side includes a plurality of
protrusions having a pattern. A plurality of discrete protrusions
is disposed on and aligned with the plurality of protrusions of the
polishing side of the homogeneous body. The plurality of discrete
protrusions is composed of a material having a second hardness
different from the first hardness. The plurality of discrete
protrusions has the pattern. A fill layer is disposed on the
homogeneous body, around the plurality of protrusions of the
polishing side of the homogeneous body. The fill layer is composed
of the material of the plurality of discrete protrusions.
[0009] In another embodiment, a method of fabricating a polishing
pad for polishing a substrate includes mixing a first set of
polymerizable materials to form a first mixture in the base of a
formation mold. The first mixture is at least partially cured to
form a molded homogeneous body having a polishing side and a back
side. A second set of polymerizable materials is mixed to form a
second mixture on the molded homogeneous body. A lid of the
formation mold is placed into the second mixture. The lid has
disposed thereon a pattern of grooves. With the lid placed in the
second mixture, the second mixture is at least partially cured to
form a plurality of discrete protrusions disposed on the polishing
side of the molded homogeneous body. The plurality of discrete
protrusions has a pattern corresponding to the pattern of grooves
of the lid.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] FIG. 1 illustrates a cross-sectional view of a polishing pad
with a homogeneous body having discrete protrusions thereon, in
accordance with an embodiment of the present invention.
[0011] FIG. 2 illustrates a cross-sectional view of another
polishing pad with a homogeneous body having discrete protrusions
thereon, in accordance with an embodiment of the present
invention.
[0012] FIG. 3 illustrates a top-down view of a polishing pad with a
homogeneous body having discrete hexagonal tile protrusions
thereon, in accordance with an embodiment of the present
invention.
[0013] FIG. 4 illustrates a top-down view of a polishing pad with a
homogeneous body having discrete arc-shaped protrusions thereon, in
accordance with an embodiment of the present invention.
[0014] FIG. 5 illustrates a top-down view of a polishing pad with a
homogeneous body having discrete linear segment protrusions
thereon, in accordance with an embodiment of the present
invention.
[0015] FIG. 6 illustrates a top-down plan view of a polishing pad
with a homogeneous body having discrete protrusions thereon and
including a local area transparency (LAT) region and/or an
indication region, in accordance with an embodiment of the present
invention.
[0016] FIGS. 7A-7G illustrate cross-sectional views of operations
used in the fabrication of a polishing pad with a homogeneous body
having discrete protrusions thereon, in accordance with an
embodiment of the present invention.
[0017] FIGS. 8A-8D illustrate cross-sectional views of operations
used in the fabrication of another polishing pad with a homogeneous
body having discrete protrusions thereon, in accordance with an
embodiment of the present invention.
[0018] FIG. 9 illustrates an isometric side-on view of a polishing
apparatus compatible with a polishing pad with a homogeneous body
having discrete protrusions thereon, in accordance with an
embodiment of the present invention.
DETAILED DESCRIPTION
[0019] Polishing pads with homogeneous bodies having discrete
protrusions thereon are described herein. In the following
description, numerous specific details are set forth, such as
specific polishing pad compositions and designs, in order to
provide a thorough understanding of embodiments of the present
invention. It will be apparent to one skilled in the art that
embodiments of the present invention may be practiced without these
specific details. In other instances, well-known processing
techniques, such as details concerning the combination of a slurry
with a polishing pad to perform CMP of a semiconductor substrate,
are not described in detail in order to not unnecessarily obscure
embodiments of the present invention. Furthermore, it is to be
understood that the various embodiments shown in the figures are
illustrative representations and are not necessarily drawn to
scale.
[0020] Polishing pads for CMP operations may have trade-offs in
performance such as between across-wafer polishing uniformity
versus within die polishing uniformity. For example, hard polishing
pads may exhibit good die-level planarization, but poor
across-wafer uniformity. On the other hand, soft polishing pads may
exhibit poor die-level planarization (e.g., they may cause dishing
within die), but good wafer-level uniformity. An approach to
mitigating the above performance trade-off may be to decouple
within-wafer and within-die polishing effects.
[0021] In one attempt, a soft subpad has been paired with a hard
polishing layer. However, the structures that make of the hard
polishing layer, such as tile structures, tend to unfavorably lean
over when compressed into the soft subpad during a polishing
operation. Furthermore, delamination of the features of the hard
polishing layer from the soft subpad can significantly reduce the
life of the polishing pad.
[0022] In accordance with embodiments of the present invention,
approaches to mitigating the above described performance trade-off
include the formation of polishing pads having hard discrete
protrusions covalently bonded with a soft homogeneous body. Other
polishing pads have hard discrete protrusions disposed on a soft
homogeneous body having hard lateral supporting, yet discontinuous,
features to inhibit toppling of the discrete protrusions during
compression into the underlying homogeneous body. It is to be
understood that reverse arrangements, e.g., soft polishing
protrusions disposed on hard underlying homogeneous bodies are also
contemplated herein.
[0023] Such multi-layer polishing pads may be fabricated with a
molding process to ensure chemical bonding between the protrusions
and the underlying homogeneous body. For example, in one
embodiment, a multi-layer CMP pads is fabricated in-situ by forming
a second pad precursor above a partially cured first pad precursor
and further curing both portions together. The first material may
be pre-pressed or may not be not-pressed. In either case, the whole
pad is pressed and post-cured as an integral polishing pad. By
using such an in-situ approach, chemical bonding between layers may
be very strong, reducing or eliminating any potential for
delamination. In an embodiment, pre-pressing or pressing involves
the moving together of upper and lower portions of a molding
apparatus.
[0024] In an aspect of the present invention, a polishing pad is
provided with a substantially flat homogeneous body having discrete
protrusions thereon. For example, FIG. 1 illustrates a
cross-sectional view of a polishing pad with a homogeneous body
having discrete protrusions thereon, in accordance with an
embodiment of the present invention.
[0025] Referring to FIG. 1, a polishing pad 100 is provided for
polishing a substrate. The polishing pad 100 includes a homogeneous
body 102 having a polishing side 104 and a back side 106. The
homogeneous body 102 is composed of a material having a first
hardness. The polishing pad 100 also includes a plurality of
discrete protrusions 108 disposed on the polishing side 104 of the
homogeneous body 102. The plurality of discrete protrusions 108 is
composed of a material having a second hardness, different from the
first hardness. In an embodiment, the polishing side 104 of the
homogeneous body 102 is substantially flat and is exposed between
the plurality of discrete protrusions 108, as depicted in FIG. 1.
In one such embodiment, each of the plurality of discrete
protrusions 108 has, in a global plane of the polishing side 104 of
the homogeneous body 102, a shortest dimension approximately in the
range of 5-50 millimeters.
[0026] In accordance with an embodiment of the present invention,
the hardness of the material of the homogeneous body 102 (first
hardness) is less than the hardness of the material of the
plurality of discrete protrusions 108 (second hardness). In one
such embodiment, the first hardness is less than approximately 40
Shore D, and the second hardness is greater than approximately 30
Shore D. In a specific such embodiment, the first hardness is less
than approximately 25 Shore D, and the second hardness is greater
than approximately 40 Shore D.
[0027] In accordance with another embodiment of the present
invention, the hardness of the material of the homogeneous body 102
(first hardness) is greater than the hardness of the material of
the plurality of discrete protrusions 108 (second hardness). In one
such embodiment, the second hardness is less than approximately 40
Shore D, and the first hardness is greater than approximately 30
Shore D. In a specific such embodiment, the second hardness is less
than approximately 25 Shore D, and the first hardness is greater
than approximately 40 Shore D.
[0028] In another aspect of the present invention, a polishing pad
is provided with a topographically patterned homogeneous body
having discrete protrusions thereon. For example, FIG. 2
illustrates a cross-sectional view of another polishing pad with a
homogeneous body having discrete protrusions thereon, in accordance
with an embodiment of the present invention.
[0029] Referring to FIG. 2, a polishing pad 200 is provided for
polishing a substrate. The polishing pad 200 includes a homogeneous
body 202 having a polishing side 204 and a back side 206. The
homogeneous body 202 is composed of a material having a first
hardness. The polishing side 204 of the homogeneous body 202
includes a plurality of protrusions 207 having a pattern. The
polishing pad 200 also includes a plurality of discrete protrusions
208 disposed on and aligned with the plurality of protrusions 207
of the polishing side 204 of the homogeneous body 202. The
plurality of discrete protrusions 208 has the pattern of the
plurality of protrusions 207 and is composed of a material having a
second hardness, different from the first hardness. Polishing pad
200 also includes a fill layer 210 disposed on the homogeneous body
202, around the plurality of protrusions 207 of the polishing side
204 of the homogeneous body 202. The fill layer is composed the
material of the plurality of discrete protrusions 208. In one such
embodiment, each of the plurality of protrusions 207 and each of
the plurality of discrete protrusions 208 has, in a global plane of
the polishing side 204 of the homogeneous body 202, a shortest
dimension approximately in the range of 5-50 millimeters.
[0030] In an embodiment, the fill layer 210 is discontinuous with
the plurality of discrete protrusions 208. That is, referring to
FIG. 2, the fill layer is not bonded to or continuous with the
plurality of discrete protrusions 208 at locations 212. Such an
arrangement may enable freedom of compression of each of the
plurality of discrete protrusions 208 into the homogeneous body 208
during a polishing process. Yet, the presence of discontinuous fill
layer 210 may guide and support either side of each of the
plurality of discrete protrusions 208 as they are compressed into
the homogeneous body 208. However, in an alternative embodiment,
the fill layer 210 is continuous with the plurality of discrete
protrusions 208.
[0031] In accordance with an embodiment of the present invention,
the hardness of the material of the homogeneous body 202 (first
hardness) is less than the hardness of the material of the
plurality of discrete protrusions 208 and the fill layer 210
(second hardness). In one such embodiment, the first hardness is
less than approximately 40 Shore D, and the second hardness is
greater than approximately 30 Shore D. In a specific such
embodiment, the first hardness is less than approximately 25 Shore
D, and the second hardness is greater than approximately 40 Shore
D.
[0032] In accordance with another embodiment of the present
invention, the hardness of the material of the homogeneous body 208
(first hardness) is greater than the hardness of the material of
the plurality of discrete protrusions 208 and the fill layer 210
(second hardness). In one such embodiment, the second hardness is
less than approximately 40 Shore D, and the first hardness is
greater than approximately 30 Shore D. In a specific such
embodiment, the second hardness is less than approximately 25 Shore
D, and the first hardness is greater than approximately 40 Shore
D.
[0033] Portions of differing materials within the polishing pads
100 and 200 may be covalently bonded with one another. For example,
referring to FIG. 1, in an embodiment, the plurality of discrete
protrusions 108 is disposed on and covalently bonded with the
polishing side 104 of the homogeneous body 102. In another example,
referring to FIG. 2, in an embodiment, both the fill layer 210 and
the plurality of discrete protrusions 208 are covalently bonded
with the homogeneous body 202. Specifically, the fill layer 210 is
covalently bonded within the pattern of the polishing side 204,
while the plurality of discrete protrusions 208 is covalently
bonded on top of the pattern of the polishing side 204.
[0034] In an embodiment, the term "covalently bonded" refers to
arrangements where atoms from a first material (e.g., the material
of homogeneous body 102 or 202) are cross-linked or share electrons
with atoms from a second material (e.g., the material of the
plurality of discrete protrusions 108 or 208) to effect actual
chemical bonding. Such covalent bonding is distinguished from
electrostatic interactions that may result if a portion of a
polishing pad is cut out and replaced with an insert region of s
differing material. Covalent bonding is also distinguished from
mechanical bonding, such as bonding through screws, nails, glues,
or other adhesives. As described in detail below, the covalent
bonding may be achieved by co-curing, at least to some extent, a
polishing body with a plurality of discrete protrusions, as opposed
to through separate formation of the polishing body and the
plurality of discrete protrusions.
[0035] The materials of polishing pads 100 or 200 may be molded.
For example, referring to FIG. 1, in an embodiment, the homogeneous
body 102 is a molded homogeneous body, and the plurality of
discrete protrusions 108 is a plurality of molded protrusions. In
another example, referring to FIG. 2, in an embodiment, the
homogeneous body 208 is a molded homogeneous body, the plurality of
discrete protrusions 208 is a plurality of molded protrusions, and
the fill layer 210 is a molded fill layer.
[0036] The term "molded" may be used to indicate that a homogeneous
body and/or discrete protrusions thereon are formed in a formation
mold, as described in more detail below in association with FIGS.
7A-7G and 8A-8D. In an embodiment, the molded discrete protrusions,
upon conditioning and/or polishing, have a polishing surface
roughness approximately in the range of 1-5 microns root mean
square. In one embodiment, the molded discrete protrusions, upon
conditioning and/or polishing, have a polishing surface roughness
of approximately 2.35 microns root mean square. In an embodiment,
the molded discrete protrusions have a storage modulus at 25
degrees Celsius approximately in the range of 30-500 megaPascals
(MPa). In another embodiment, the molded discrete protrusions have
a storage modulus at 25 degrees Celsius approximately less than 30
megaPascals (MPa). In an embodiment, as described in association
with FIGS. 7A-7G and 8A-8D, a polishing pad is composed of a molded
polishing body and molded discrete protrusions thereon.
[0037] The polishing pads 100 or 200 may include a homogeneous body
composed of a thermoset polyurethane material. In an embodiment,
the homogeneous body is composed of a thermoset, closed cell
polyurethane material. In an embodiment, the term "homogeneous" is
used to indicate that the composition of a thermoset, closed cell
polyurethane material is consistent throughout the entire
composition of the body. For example, in an embodiment, the term
"homogeneous" excludes polishing pad bodies composed of, e.g.,
impregnated felt or a composition (composite) of multiple layers of
differing material.
[0038] In an embodiment, the term "thermoset" is used to indicate a
polymer material that irreversibly cures, e.g., the precursor to
the material changes irreversibly into an infusible, insoluble
polymer network by curing. For example, in an embodiment, the term
"thermoset" excludes polishing pads composed of, e.g.,
"thermoplast" materials or "thermoplastics"--those materials
composed of a polymer that turns to a liquid when heated and
returns to a very glassy state when cooled sufficiently. It is
noted that polishing pads made from thermoset materials are
typically fabricated from lower molecular weight precursors
reacting to form a polymer in a chemical reaction, while pads made
from thermoplastic materials are typically fabricated by heating a
pre-existing polymer to cause a phase change so that a polishing
pad is formed in a physical process. Polyurethane thermoset
polymers may be selected for fabricating polishing pads described
herein based on their stable thermal and mechanical properties,
resistance to the chemical environment, and tendency for wear
resistance.
[0039] In one embodiment, referring to FIG. 1, the material of the
homogeneous body 102 is composed of a first thermoset polyurethane
material, and the material of the plurality of discrete protrusions
108 is composed of a second, different, thermoset polyurethane
material. In one embodiment, referring to FIG. 2, the material of
the homogeneous body 202 is composed of a first thermoset
polyurethane material, and the material of the plurality of
discrete protrusions 208 and the fill layer 210 is composed of a
second, different, thermoset polyurethane material.
[0040] In an embodiment, polishing pads described herein, such as
polishing pads 100 or 200, include a polishing body and/or discrete
protrusions thereon having a plurality of closed cell pores
therein. In one embodiment, the plurality of closed cell pores is a
plurality of porogens. For example, the term "porogen" may be used
to indicate micro- or nano-scale spherical or somewhat spherical
particles with "hollow" centers. The hollow centers are not filled
with solid material, but may rather include a gaseous or liquid
core. In one embodiment, the plurality of closed cell pores is
composed of pre-expanded and gas-filled EXPANCEL.TM. distributed
throughout (e.g., as an additional component in) a polishing body
and/or discrete protrusions of a polishing pad. In a specific
embodiment, the EXPANCEL.TM. is filled with pentane. In an
embodiment, each of the plurality of closed cell pores has a
diameter approximately in the range of 10-100 microns. In an
embodiment, the plurality of closed cell pores includes pores that
are discrete from one another. This is in contrast to open cell
pores which may be connected to one another through tunnels, such
as the case for the pores in a common sponge. In one embodiment,
each of the closed cell pores includes a physical shell, such as a
shell of a porogen, as described above. In another embodiment,
however, each of the closed cell pores does not include a physical
shell. In an embodiment, the plurality of closed cell pores is
distributed essentially evenly throughout a thermoset polyurethane
material of a homogeneous body or of a homogeneous plurality of
discrete protrusions disposed thereon.
[0041] In an embodiment, the density or concentration of the
plurality of closed cells differs between the homogeneous body
(e.g., 102 or 202) and the plurality of discrete protrusions (e.g.,
108 or 208). In one such embodiment, the density or concentration
of closed cells in the homogeneous body is less than that in the
plurality of discrete protrusions. In a specific such embodiment,
there are no closed cells in the homogeneous body while there are
closed cells in the plurality of discrete protrusions. In an
alternative embodiment, the density or concentration of closed
cells in the homogeneous body is greater than that in the plurality
of discrete protrusions. In another embodiment, the type of closed
cells differs between the homogeneous body and the plurality of
discrete protrusions.
[0042] In an embodiment, polishing pads described herein, such as
polishing pads 100 or 200, include a polishing body and/or discrete
protrusions that are opaque. In one embodiment, the term "opaque"
is used to indicate a material that allows approximately 10% or
less visible light to pass. In one embodiment, the polishing body
and/or discrete protrusions are opaque in most part, or due
entirely to, the inclusion of an opacifying particle filler, such
as a lubricant, throughout (e.g., as an additional component in)
the polishing body and/or discrete protrusions. In a specific
embodiment, the opacifying particle filler is a material such as,
but not limited to: boron nitride, cerium fluoride, graphite,
graphite fluoride, molybdenum sulfide, niobium sulfide, talc,
tantalum sulfide, tungsten disulfide, or Teflon.RTM..
[0043] In an embodiment, the degree of opaqueness or the
concentration of particle filler differs between the homogeneous
body (e.g., 102 or 202) and the plurality of discrete protrusions
(e.g., 108 or 208). In one such embodiment, the concentration of
particle filler in the homogeneous body is less than that in the
plurality of discrete protrusions. In a specific such embodiment,
there is no particle filler included in the homogeneous body while
particle filler is included in the plurality of discrete
protrusions. In an alternative embodiment, the concentration of
particle filler in the homogeneous body is greater than that in the
plurality of discrete protrusions. In another embodiment, the type
of particle filler differs between the homogeneous body and the
plurality of discrete protrusions.
[0044] In an aspect of the present invention, the plurality of
discrete protrusions 108 or 208 may have a pattern suitable for
polishing during a CMP operation. In a first general example, some
embodiments of the present invention include a plurality of
discrete protrusions having a pattern of tiles. In a specific such
embodiment, FIG. 3 illustrates a top-down view of a polishing pad
300 with a homogeneous body having discrete hexagonal tile
protrusions 302 thereon, in accordance with an embodiment of the
present invention. Other specific such embodiments include, but are
not limited to, pluralities of circular tiles, oval tiles, square
tiles, rectangular tiles, or a combination thereof.
[0045] In a second general example, some embodiments of the present
invention include a plurality of discrete protrusions having a
pattern of curved features. In a specific such example, FIG. 4
illustrates a top-down view of a polishing pad 400 with a
homogeneous body having discrete arc-shaped protrusions 402
thereon, in accordance with an embodiment of the present invention.
Other specific such embodiments include, but are not limited to, a
plurality of partial circumferential protrusions disposed on a
substantially circular homogenous body of the polishing pad.
[0046] In a third general example, some embodiments of the present
invention include a plurality of discrete protrusions having a
pattern of linear features. In a specific such example, FIG. 5
illustrates a top-down view of a polishing pad 500 with a
homogeneous body having discrete linear segment protrusions 502
thereon, in accordance with an embodiment of the present invention.
The discrete linear segment protrusions shown are essentially
orthogonal to radii of the polishing surface. It is to be
understood, however, that embodiments of the present invention may
also include discrete linear segments that are not precisely
orthogonal to radii of the polishing surface. In such embodiments,
the discrete linear segments may form a portion of a, but not a
complete, concentric or approximately concentric polygon
arrangement. The relative association with the corresponding radius
in not precisely 90 degrees but rather, perhaps, a fraction of a
degree to a few degrees off of 90 degrees. Nonetheless, such
near-orthogonal or approximately orthogonal discrete linear
segments are considered to be within the spirit and scope of the
present invention.
[0047] In an embodiment, polishing pads described herein, such as
polishing pads 100, 200, 300, 400 or 500, are suitable for
polishing substrates. The substrate may be one used in the
semiconductor manufacturing industry, such as a silicon substrate
having device or other layers disposed thereon. However, the
substrate may be one such as, but not limited to, a substrates for
MEMS devices, reticles, or solar modules. Thus, reference to "a
polishing pad for polishing a substrate," as used herein, is
intended to encompass these and related possibilities.
[0048] The sizing of the homogeneous body and the discrete
protrusions disposed thereon may be varied according to
application. Nonetheless, certain parameters may be used to make
polishing pads including such a homogeneous body with discrete
protrusions disposed thereon compatible with conventional
processing equipment or even with conventional chemical mechanical
processing operations. For example, in accordance with an
embodiment of the present invention, the combination of the
homogeneous body and the discrete protrusions disposed thereon has
a thickness approximately in the range of 0.075 inches to 0.130
inches, e.g., approximately in the range of 1.9-3.3 millimeters. In
one embodiment, the homogeneous body has a diameter approximately
in the range of 20 inches to 30.3 inches, e.g., approximately in
the range of 50-77 centimeters, and possibly approximately in the
range of 10 inches to 42 inches, e.g., approximately in the range
of 25-107 centimeters. In one embodiment, the homogeneous body
and/or the discrete protrusions disposed thereon have a pore
density approximately in the range of 6%-36% total void volume, and
possibly approximately in the range of 15%-35% total void volume.
In one embodiment, the combination of the homogeneous body and the
discrete protrusions disposed thereon has a compressibility of
approximately 2.5%. In one embodiment, the homogeneous body has a
density approximately in the range of 0.70-1.05 grams per cubic
centimeter.
[0049] In another aspect of the present invention, a polishing pad
with a homogeneous body having discrete protrusions thereon further
includes a detection region for use with, e.g., an eddy current
detection system. For example, FIG. 6 illustrates a top-down plan
view of a polishing pad 600 with a homogeneous body having discrete
protrusions thereon and including a local area transparency (LAT)
region and/or an indication region, in accordance with an
embodiment of the present invention.
[0050] Referring to FIG. 6, the polishing surface 602 of polishing
pad 600 includes an indication region 604 indicating the location
of a detection region disposed in the back surface of the polishing
pad 600. In one embodiment, the indication region 604 interrupts a
pattern of protrusions 606 with a second pattern of protrusions
608, as depicted in FIG. 6. Examples of suitable detection regions,
such as eddy current detection regions, are described in U.S.
patent application Ser. No. 12/895,465 filed on Sep. 30, 2010,
assigned to NexPlanar Corporation.
[0051] In another aspect, a polishing pad with a homogeneous body
having discrete protrusions thereon further includes further
includes a local area transparency (LAT) region disposed in the
polishing pad. For example, referring again to FIG. 6, a LAT region
610 is disposed in the polishing body of polishing pad 600. As
depicted in FIG. 6, the LAT region 604 interrupts the pattern of
protrusions 606. In an embodiment, the LAT region 610 is disposed
in, and covalently bonded with, a homogeneous body of the polishing
pad 600. Examples of suitable LAT regions are described in U.S.
patent application Ser. No. 12/895,465 filed on Sep. 30, 2010,
assigned to NexPlanar Corporation.
[0052] In another aspect of the present invention, polishing pads
having a homogeneous body with a plurality of discrete protrusions
disposed thereon may be fabricated in a molding process. In a first
such example, FIGS. 7A-7G illustrate cross-sectional views of
operations used in the fabrication of a polishing pad with a
homogeneous body having discrete protrusions thereon, in accordance
with an embodiment of the present invention.
[0053] Referring to FIG. 7A, a formation mold 700 is provided.
Referring to FIG. 7B, a pre-polymer 702 and a curative 704 are
mixed to form a first mixture 706 in the formation mold 700, as
depicted in FIG. 7C. In an embodiment, mixing the pre-polymer 702
and the curative 704 includes mixing an isocyanate and an aromatic
diamine compound, respectively. In one embodiment, the mixing
further includes adding an opacifying particle filler to the
pre-polymer 702 and the curative 704 to ultimately provide an
opaque molded homogeneous body of a polishing pad. In a specific
embodiment, the opacifying particle filler is a material such as,
but not limited to: boron nitride, cerium fluoride, graphite,
graphite fluoride, molybdenum sulfide, niobium sulfide, talc,
tantalum sulfide, tungsten disulfide, or Teflon.
[0054] In an embodiment, the first mixture 706 is used to
ultimately form a molded homogeneous body composed of a thermoset,
closed cell polyurethane material. In one embodiment, the first
mixture 706 is used to ultimately form a hard homogeneous body and
only a single type of curative is used. In another embodiment, the
first mixture 706 is used to ultimately form a soft homogeneous
body and a combination of a primary and a secondary curative is
used. For example, in a specific embodiment, the pre-polymer
includes a polyurethane precursor, the primary curative includes an
aromatic diamine compound, and the secondary curative includes a
compound having an ether linkage. In a particular embodiment, the
polyurethane precursor is an isocyanate, the primary curative is an
aromatic diamine, and the secondary curative is a curative such as,
but not limited to, polytetramethylene glycol, amino-functionalized
glycol, or amino-functionalized polyoxypropylene. In an embodiment,
the pre-polymer, a primary curative, and a secondary curative have
an approximate molar ratio of 100 parts pre-polymer, 85 parts
primary curative, and 15 parts secondary curative. It is to be
understood that variations of the ratio may be used to provide a
homogeneous body with varying hardness values, or based on the
specific nature of the pre-polymer and the first and second
curatives.
[0055] Referring to FIG. 7D, the mixture 706 is at least partially
cured to form a molded homogeneous body 708 having a polishing side
710 and a back side 712. The partial curing may be performed by
heating the mold 700 in the presence or absence of a formation mold
lid. A second pre-polymer and a second curative are then mixed to
form a second mixture 714 on the molded homogeneous body 708, as
depicted in FIG. 7E. In an embodiment, the second mixture 714 is
for forming a hard material, and a pre-polymer along with a single
curative is used (2-tank process), while the first mixture 706 is
for forming a soft material, and a pre-polymer along with a primary
curative and a secondary curative is used (3-tank process). In an
alternative embodiment, the first mixture 706 is for forming a hard
material, and a pre-polymer along with a single curative is used
(2-tank process), while the second mixture 714 is for forming a
soft material, and a pre-polymer along with a primary curative and
a secondary curative is used (3-tank process). Thus, in an
embodiment, the second mixture 714 is different from the first
mixture 706. However, in an alternative embodiment, the two
mixtures are the same. Also, in an embodiment, the second mixture
is dispensed on a partially or completely cured first mixture 706.
However, in an alternative embodiment, the pouring or dispensing of
the second mixture 714 may be poured in situ into the first mixture
706 to be applied for the same layer, but in a different region. In
a specific such embodiment, the center ring and outer ring have
different formulations. In an embodiment where two distinct layers
are formed, in order to strengthen the chemical bonding between
layers, the ratio of functional group within different layers is
different, e.g., one layer is --NCO rich and the other layer is
--NH.sub.2 and/or --OH rich. In an embodiment, a coating is applied
between different layers. In an embodiment, penetration occurs
between layers and strengthens the chemical bonding, such as the
covalent bonding.
[0056] In an embodiment, the mixing of the second pre-polymer and
the second curative further includes adding an opacifying particle
filler to the second pre-polymer and the second curative to form an
opaque plurality of discrete protrusions 718. In an embodiment,
mixing the first pre-polymer and the first curative to form the
first mixture 706 includes degassing the first mixture 706, and
mixing the second pre-polymer and the second curative to form the
second mixture 714 includes degassing the second mixture 714.
[0057] Referring to FIG. 7F, a lid 716 of the formation mold 700 is
placed into the second mixture 714. A top-down plan view of lid 716
is shown on top, while a cross-section along the a-a' axis is shown
below in FIG. 7F. The lid 716 has disposed thereon a pattern of
grooves, such as a pattern of grooves corresponding to the pattern
of protrusions described in association with FIG. 3, as depicted in
FIG. 7F. Alternatively, however, lid 716 has disposed thereon a
pattern of grooves corresponding to the patterns of protrusions
described in association with FIGS. 4 and 5.
[0058] It is to be understood that embodiments described herein
that describe lowering the lid 716 of a formation mold 700 need
only achieve a bringing together of the lid 716 and a base of the
formation mold 700. That is, in some embodiments, a base of a
formation mold 700 is raised toward a lid 716 of a formation mold,
while in other embodiments a lid 716 of a formation mold 700 is
lowered toward a base of the formation mold 700 at the same time as
the base is raised toward the lid 716.
[0059] With the lid 716 placed in the second mixture 714, the
second mixture 714 is at least partially cured to form a plurality
of discrete protrusions 718 disposed on the polishing side 710 of
the molded homogeneous body 708. The pattern of grooves of the lid
716 is used to stamp a pattern of protrusions from the second
mixture 714 in the formation mold 700. The second mixture 714 may
be heated under pressure (e.g., with the lid 716 in place) to
provide the molded discrete protrusions 718. In an embodiment,
heating in the formation mold 700 includes at least partially
curing in the presence of lid 716, which encloses the second
mixture 714 in formation mold 700, at a temperature approximately
in the range of 200-260 degrees Fahrenheit and a pressure
approximately in the range of 2-12 pounds per square inch.
[0060] In an embodiment, the second mixture 714 is different from
the first mixture 706, and, upon fully curing the first 706 and
second 714 mixtures, the hardness of the plurality of discrete
protrusions 718 is different from the hardness of the molded
homogeneous body 708. In an embodiment, at least partially curing
the second mixture 714 includes covalently boding the plurality of
discrete protrusions 718 with the molded homogeneous body 708. In
an embodiment, forming the molded homogeneous body 708 includes
forming a first thermoset polyurethane material, and forming the
plurality of discrete protrusions 718 includes forming a second,
different, thermoset polyurethane material.
[0061] Referring to FIG. 7G, a polishing pad 720 is provided upon
removal of the molded homogeneous body 708 with the plurality of
discrete protrusions 718 disposed thereon from the formation mold
700. The plurality of discrete protrusions 718 has a pattern
corresponding to the pattern of grooves of the lid 716. A top-down
plan view of the polishing pad 720 is shown below, while a
cross-section taken along the b-b' axis is shown above in FIG. 7G.
In an embodiment, the polishing side 710 of the molded homogeneous
body 708 is substantially flat and is exposed between the plurality
of discrete protrusions 718, as depicted in the cross-sectional
view of FIG. 7G.
[0062] It is noted that further curing through heating may be
desirable and may be performed by placing the polishing pad 720 in
an oven and heating. Thus, in one embodiment, curing the first and
second mixtures 706 and 714 includes first partially curing in the
formation mold 700 and then further curing in an oven. Either way,
a polishing pad 720 is ultimately provided, wherein a molded
homogeneous body 708 of the polishing pad 720 has a polishing side
710 with a plurality of molded protrusions 718 disposed thereon. In
an embodiment, both the molded homogeneous body 708 and the
plurality of molded protrusions 718 are composed of thermoset
polyurethane materials and a plurality of closed cell pores
disposed in the thermoset polyurethane materials.
[0063] A similar method to the one described in association with
FIG. 7A-7G may be used to fabricate a polishing pad with a
topographically patterned homogeneous body having discrete
protrusions thereon. For example, FIGS. 8A-8D illustrate
cross-sectional views of operations used in the fabrication of
another polishing pad with a homogeneous body having discrete
protrusions thereon, in accordance with an embodiment of the
present invention.
[0064] Referring again to FIG. 7C, and now to FIG. 8A, instead of
at least partially curing the first mixture 706 to provide a
substantially flat surface for a homogeneous body 708, the lid 716
(described in association with FIG. 7F) is used to first form
molded homogeneous body 800 with a polishing side 802 having a
plurality of protrusions 804 with a pattern corresponding to the
pattern of grooves of the lid 716. For example, subsequent to
mixing the first pre-polymer and the first curative to form the
first mixture 706 but prior to mixing the second pre-polymer and
the second curative to form the second mixture 714, the lid 716 of
the formation mold 700 is placed into the first mixture 706. With
the lid placed in the first mixture 706, the first mixture 706 is
at least partially cured, as depicted in FIG. 8B.
[0065] Referring to FIG. 8C, the second pre-polymer and the second
curative are then mixed to form the second mixture 714 on the
molded homogeneous body 800. The lid 716 of the formation mold 700
is then placed into the second mixture 714, as depicted in FIG. 8D.
With the lid 716 placed in the second mixture 714, the second
mixture 714 is at least partially cured to form a plurality of
discrete protrusions 718 disposed on and aligned with the plurality
of protrusions 804 of the polishing side 802 of the molded
homogeneous body 800. The pattern of grooves of the lid 716 is used
to stamp a pattern of protrusions from the second mixture 714 in
the formation mold 700. The second mixture 714 may then be heated
under pressure (e.g., with the lid 716 in place) to provide the
molded discrete protrusions 718. In an embodiment, heating in the
formation mold 700 includes at least partially curing in the
presence of lid 716, which encloses the second mixture 714 in
formation mold 700, at a temperature approximately in the range of
200-260 degrees Fahrenheit and a pressure approximately in the
range of 2-12 pounds per square inch. A polishing pad such as the
polishing pad 200 described in association with FIG. 2 may thus be
formed.
[0066] Referring again to FIG. 8D, in an embodiment, forming the
second mixture 714 on the molded homogeneous body 800 includes
forming an amount of the second mixture 714 sufficiently large to
form a fill layer 806 disposed on the molded homogeneous body 800,
around the plurality of protrusions 804 of the polishing side 802
of the molded homogeneous body 800. In one such embodiment, the
amount of the second mixture 714 is sufficiently small to form the
fill layer 806 discontinuous with the plurality of discrete
protrusions 718 formed from the second mixture 714. An example of
such discontinuity is described above in association with polishing
pad 200 of FIG. 2. In an embodiment, a spin plate is used to
control the amount and thickness of the second mixture 714
dispensed on the polishing side 802 of the molded homogeneous body
800.
[0067] In an embodiment, the plurality of discrete protrusions 718
is formed on and aligned with the plurality of protrusions 804 of
the polishing side 802 of the molded homogeneous body 800. The
alignment may tolerate some slight misalignment. For example, a
slippage approximately in the range of up to 1/1000.sup.th on an
inch may be acceptable between separate introduction of the lid 716
into the first mixture 706 and the second mixture 714,
respectively.
[0068] In an embodiment, referring again to FIG. 7B, the mixing
further includes adding a plurality of porogens 722 to the
pre-polymer 702 and the curative 704 to provide closed cell pores
in the ultimately formed body of the polishing pad. Thus, in one
embodiment, each closed cell pore has a physical shell. In another
embodiment, referring again to FIG. 7B, the mixing further includes
injecting a gas 724 into to the pre-polymer 702 and the curative
704, or into a product formed there from, to provide closed cell
pores in the ultimately formed body of the polishing pad. Thus, in
one embodiment, each closed cell pore has no physical shell. In a
combination embodiment, the mixing further includes adding a
plurality of porogens 722 to the pre-polymer 702 and the curative
704 to provide a first portion of closed cell pores each having a
physical shell, and further injecting a gas 724 into the
pre-polymer 702 and the curative 704, or into a product formed
there from, to provide a second portion of closed cell pores each
having no physical shell. In yet another embodiment, the
pre-polymer 702 is an isocyanate and the mixing further includes
adding water (H.sub.2O) to the pre-polymer 702 and the curative 704
to provide closed cell pores each having no physical shell. In an
embodiment, referring to FIGS. 7E and 8C, a plurality of porogens
may similarly be included in a molded discrete plurality of
protrusions 718.
[0069] Thus, protrusion patterns contemplated in embodiments of the
present invention may be formed in-situ. For example, as described
above, a compression-molding process may be used to form polishing
pads with a molded homogeneous body having molded discrete
protrusions disposed thereon. By using a molding process, highly
uniform protrusion dimensions within-pad may be achieved.
Furthermore, extremely reproducible protrusion dimensions along
with very smooth, clean protrusion surfaces may be produced. Other
advantages may include reduced defects and micro-scratches and a
greater usable protrusion depth.
[0070] Polishing pads described herein may be suitable for use with
a variety of chemical mechanical polishing apparatuses. As an
example, FIG. 9 illustrates an isometric side-on view of a
polishing apparatus compatible with a polishing pad with a
homogeneous body having discrete protrusions thereon, in accordance
with an embodiment of the present invention.
[0071] Referring to FIG. 9, a polishing apparatus 900 includes a
platen 904. The top surface 902 of platen 904 may be used to
support a polishing pad with a homogeneous body having discrete
protrusions thereon. Platen 904 may be configured to provide
spindle rotation 906 and slider oscillation 908. A sample carrier
910 is used to hold, e.g., a semiconductor wafer 911 in place
during polishing of the semiconductor wafer with a polishing pad.
Sample carrier 910 is further supported by a suspension mechanism
912. A slurry feed 914 is included for providing slurry to a
surface of a polishing pad prior to and during polishing of the
semiconductor wafer. A conditioning unit 990 may also be included
and, in one embodiment, includes a diamond tip for conditioning a
polishing pad.
[0072] Thus, polishing pads with homogeneous bodies having discrete
protrusions thereon have been disclosed. In accordance with an
embodiment of the present invention, a polishing pad for polishing
a substrate includes a homogeneous body having a polishing side and
a back side. The homogeneous body is composed of a material having
a first hardness. A plurality of discrete protrusions is disposed
on and covalently bonded with the polishing side of the homogeneous
body. The plurality of discrete protrusions is composed of a
material having a second hardness different from the first
hardness. In one embodiment, the polishing side of the homogeneous
body is substantially flat and is exposed between the plurality of
discrete protrusions. In one embodiment, a fill layer is disposed
on the homogeneous body, around a plurality of protrusions of the
polishing side of the homogeneous body, the fill layer composed of
the material of the plurality of discrete protrusions. In one
embodiment, the homogeneous body is a molded homogeneous body, and
the plurality of discrete protrusions is a plurality of molded
protrusions.
* * * * *