U.S. patent application number 13/517367 was filed with the patent office on 2013-04-25 for organic particulate loaded polishing pads and method of making and using the same.
This patent application is currently assigned to 3M Innovative Properties Company. The applicant listed for this patent is Brian D. Goers, William D. Joseph. Invention is credited to Brian D. Goers, William D. Joseph.
Application Number | 20130102231 13/517367 |
Document ID | / |
Family ID | 44227136 |
Filed Date | 2013-04-25 |
United States Patent
Application |
20130102231 |
Kind Code |
A1 |
Joseph; William D. ; et
al. |
April 25, 2013 |
ORGANIC PARTICULATE LOADED POLISHING PADS AND METHOD OF MAKING AND
USING THE SAME
Abstract
Polishing pads including organic particulates in a continuous
polymer phase, and methods of making and using such pads in a
polishing process. In one exemplary embodiment, the polishing pads
include a multiplicity of polishing elements integrally formed in a
sheet. In another exemplary embodiment, the polishing elements are
bonded to a support layer, for example by thermal bonding. In
certain embodiments, the polishing pad may additionally include a
compliant layer affixed to the support layer, and optionally, a
polishing composition distribution layer.
Inventors: |
Joseph; William D.;
(Maplewood, MN) ; Goers; Brian D.; (Minneapolis,
MN) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Joseph; William D.
Goers; Brian D. |
Maplewood
Minneapolis |
MN
MN |
US
US |
|
|
Assignee: |
3M Innovative Properties
Company
Saint Paul
MN
|
Family ID: |
44227136 |
Appl. No.: |
13/517367 |
Filed: |
December 28, 2010 |
PCT Filed: |
December 28, 2010 |
PCT NO: |
PCT/US10/62205 |
371 Date: |
June 20, 2012 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61291182 |
Dec 30, 2009 |
|
|
|
Current U.S.
Class: |
451/59 ; 451/527;
51/297; 51/298 |
Current CPC
Class: |
B24D 11/00 20130101;
B24B 37/26 20130101; B24B 37/245 20130101; B24B 37/22 20130101 |
Class at
Publication: |
451/59 ; 451/527;
51/298; 51/297 |
International
Class: |
B24D 11/00 20060101
B24D011/00; B24B 37/24 20060101 B24B037/24 |
Claims
1. A polishing pad comprising: a sheet having a first major side
and a second major side opposite the first major side, and a
plurality of polishing elements extending outwardly from the first
major side along a first direction substantially normal to the
first major side, wherein at least a portion of the polishing
elements are integrally formed with the sheet and laterally
connected so as to restrict lateral movement of the polishing
elements with respect to one or more of the other polishing
elements, but remaining moveable in an axis substantially normal to
a polishing surface of the polishing elements, wherein at least a
portion of the plurality of polishing elements comprise an organic
particulate filler in a continuous polymer phase.
2. A polishing pad comprising a support layer having a first major
side and a second major side opposite the first major side, and a
plurality of polishing elements bonded to the first major side of
the support layer, wherein each polishing element has an exposed
polishing surface, and wherein the polishing elements extend from
the first major side of the support layer along a first direction
substantially normal to the first major side, further wherein at
least a portion of the plurality of polishing elements comprise an
organic particulate filler in a continuous polymer phase.
3. The polishing pad of claim 2, wherein each polishing element is
affixed to the first major side by bonding to the support
layer.
4-16. (canceled)
17. The polishing pad of claim 2, wherein each polishing element is
thermally bonded to the support layer.
18. The polishing pad of claim 2, wherein the support layer
comprises a thermoplastic polyurethane
19. The polishing pad of claim 1 further comprising a compliant
layer affixed to the second major side opposite the plurality of
polishing elements.
20-23. (canceled)
24. The polishing pad of claim 1, wherein each polishing element
extends along the first direction at least about 0.25 mm above a
plane including the first major side.
25. The polishing pad of claim 1, wherein the continuous polymer
phase comprises a thermoplastic polyurethane, an acrylated
polyurethane, an epoxidized polyurethane, an epoxidized rubber, a
vinyl resin, a cyclopentadiene resin, a vinyl ether resin, and
combinations thereof.
26. The polishing pad of claim 1, wherein the organic particulate
filler comprises at least one of a thermoplastic polymer, a
thermoset polymer, a water soluble polymer, or combinations
thereof.
27. The polishing pad of claim 26, wherein the organic particulate
filler comprises at least one of a polyolefin, a cyclic polyolefin,
a polyolefinic thermoplastic elastomer, polyvinyl alcohol,
poly(ethylene oxide), poly (vinyl alcohol), poly (vinyl
pyrrolidone), polyacrylic acid, poly(meth)acrylic acid, or
combinations thereof.
28-42. (canceled)
43. The polishing pad of claim 2, wherein at least one of the
polishing elements is a transparent polishing element.
44-45. (canceled)
46. The polishing pad of claim 1, further comprising at least one
transparent polishing element affixed to a transparent portion of
the sheet.
47. A method of using a polishing pad comprising: contacting a
surface of a substrate with a polishing surface of the polishing
pad of claim 1; and relatively moving the polishing pad with
respect to the substrate to abrade the surface of the
substrate.
48. (canceled)
49. A method of making a polishing pad according to claim 1,
comprising: dispersing an organic particulate filler in a curable
composition comprising a curable polymer precursor material;
dispensing the curable composition into a mold; and curing the
curable composition in the mold to form a polymeric sheet
containing the organic particulate filler dispersed in the at least
partially cured polymer precursor material, the polymeric sheet
having a first major side and a second major side opposite the
first major side, and a plurality of polishing elements extending
outwardly from the first major side along a first direction
substantially normal to the first major side, wherein the polishing
elements are integrally formed with the sheet and laterally
connected so as to restrict lateral movement of the polishing
elements with respect to one or more of the other polishing
elements, but remaining moveable in an axis substantially normal to
a polishing surface of the polishing elements.
50. (canceled)
51. The method of claim 49, wherein dispensing the curable into the
mold comprises at least one of reaction injection molding,
extrusion molding, compression molding, or a combination
thereof.
52. (canceled)
53. A method of making a polishing pad according to claim 2,
comprising: forming a plurality of polishing elements comprising an
organic particulate filler dispersed in a continuous polymer phase;
and bonding the polishing elements to a first major side of a
support layer having a second major side opposite the first major
side to form a polishing pad.
54. The method of claim 49, further comprising forming a pattern
with the plurality of polishing elements on the first major
side.
55-69. (canceled)
Description
TECHNICAL FIELD
[0001] The present disclosure relates to polishing pads, and to
methods of making and using polishing pads in a polishing process,
for example, in a chemical mechanical planarization process.
BACKGROUND
[0002] During the manufacture of semiconductor devices and
integrated circuits, silicon wafers are iteratively processed
through a series of deposition and etching steps to form overlying
material layers and device structures. A polishing technique known
as chemical mechanical planarization (CMP) may be used to remove
surface irregularities (such as bumps, areas of unequal elevation,
troughs, and trenches) remaining after the deposition and etching
steps, with the objective of obtaining a smooth wafer surface
without scratches or depressions (known as dishing), with high
uniformity across the wafer surface.
[0003] In a typical CMP polishing process, a substrate such as a
wafer is pressed against and relatively moved with respect to a
polishing pad in the presence of a working liquid that is typically
a slurry of abrasive particles in water and/or an etching
chemistry. Various CMP polishing pads for use with abrasive
slurries have been disclosed, for example, U.S. Pat. Nos.
5,257,478; 5,921,855; 6,126,532; 6,899,598 B2; and 7,267,610. Fixed
abrasive polishing pads are also known, as exemplified by U.S. Pat.
No. 6,908,366 B2, in which the abrasive particles are generally
fixed to the surface of the pad, often in the form of precisely
shaped abrasive composites extending from the pad surface.
Recently, a polishing pad having a multiplicity of polishing
elements extending from a compressible underlayer and affixed to
the underlyer by a guide plate was described in PCT International
Pub. No. WO 2006/057714. Although a wide variety of polishing pads
are known and used, the art continues to seek new and improved
polishing pads for CMP, particularly in CMP processes where larger
die diameters are being used, or where higher levels of wafer
surface flatness and polishing uniformity are required.
SUMMARY
[0004] In one aspect, the present disclosure describes a polishing
pad including a sheet having a first major side and a second major
side opposite the first major side, and a multiplicity of polishing
elements extending outwardly from the first major side along a
first direction substantially normal to the first major side,
wherein at least a portion of the polishing elements are integrally
formed with the sheet and laterally connected so as to restrict
lateral movement of the polishing elements with respect to one or
more of the other polishing elements, but remaining moveable in an
axis substantially normal to a polishing surface of the polishing
elements, wherein at least a portion of the plurality of polishing
elements comprise an organic particulate filler dispersed in a
continuous polymer phase.
[0005] In another aspect, the present disclosure describes a
polishing pad including a support layer having a first major side
and a second major side opposite the first major side, and a
multiplicity of polishing elements bonded to the first major side
of the support layer, wherein each polishing element has an exposed
polishing surface, wherein the polishing elements extend from the
first major side of the support layer along a first direction
substantially normal to the first major side, further wherein at
least a portion of the plurality of polishing elements comprise an
organic particulate filler dispersed in a continuous polymer phase.
In some exemplary embodiments, each polishing element is affixed to
the first major side by bonding to the support layer, preferably
using direct thermal bonding. In some exemplary embodiments, the
polishing elements are arranged in a two-dimensional array pattern
on the first major side.
[0006] In additional exemplary embodiments, at least one of the
polishing elements is a porous polishing element, wherein each
porous polishing element includes a multiplicity of pores. In
certain exemplary embodiments, substantially all of the polishing
elements are porous polishing elements. In some particular
exemplary embodiments, the pores are distributed throughout
substantially the entire porous polishing element.
[0007] In certain presently preferred embodiments, at least one of
the polishing elements is a transparent polishing element. In some
exemplary embodiments, the support layer, the optional guide plate,
the optional polishing composition distribution layer, the optional
compliant layer, the optional adhesive, layer, at least one
polishing element, or a combination thereof is transparent. In
certain exemplary embodiments, at least one transparent polishing
element is affixed to a transparent portion of the sheet.
[0008] In other exemplary embodiments of polishing pads as
described above, the polishing pad includes an optional compliant
layer affixed to the second major side. In further exemplary
embodiments of polishing pads as described above, the polishing pad
includes an optional pressure sensitive adhesive layer affixed to
the compliant layer opposite the second major side. In additional
exemplary embodiments, the polishing pad includes a polishing
composition distribution layer overlaying the first major side of
the sheet or support layer.
[0009] In other exemplary embodiments of polishing pads as
described above, the polishing elements further comprise abrasive
particulates having a median diameter of less than one micrometer.
In further exemplary embodiments, at least a portion of the
polishing elements is substantially free of abrasive particulates.
In additional exemplary embodiments, the polishing pads as
described above are substantially free of abrasive
particulates.
[0010] In yet another aspect, the present disclosure describes a
method of using a polishing pad as described above, the method
including contacting a surface of a substrate with a polishing
surface of the polishing pad, and relatively moving the polishing
pad with respect to the substrate to abrade the surface of the
substrate. In some exemplary embodiments, the method further
includes providing a polishing composition to an interface between
the polishing pad surface and the substrate surface.
[0011] In a further aspect, the present disclosure describes a
method of making a polishing pad as described above, the method
including forming a plurality of polishing elements comprising an
organic particulate filler dispersed in a continuous polymer phase,
and bonding the polishing elements to a first major side of a
support layer having a second major side opposite the first major
side to form a polishing pad.
[0012] In an additional aspect, the present disclosure describes a
method of making a polishing pad as described above, the method
including dispersing an organic particulate filler in a curable
composition comprising a polymeric precursor material, dispensing
the curable composition into a mold, curing the curable composition
in the mold to form a polymeric sheet containing the dispersed
organic particulate filler, the polymeric sheet having a first
major side and a second major side opposite the first major side,
and a plurality of polishing elements extending outwardly from the
first major side along a first direction substantially normal to
the first major side, wherein the polishing elements are integrally
formed with the sheet and laterally connected so as to restrict
lateral movement of the polishing elements with respect to one or
more of the other polishing elements, but remaining moveable in an
axis substantially normal to a polishing surface of the polishing
elements.
[0013] In some exemplary embodiments, dispersing the organic
particulate filler in the continuous polymer phase comprises melt
mixing, kneading, extrusion, or combinations thereof. In certain
exemplary embodiments, dispensing the fluid molding composition
into the mold comprises at least one of reaction injection molding,
extrusion molding, compression molding, vacuum molding, or a
combination thereof. In some particular exemplary embodiments,
dispensing comprises continuously extruding the fluid molding
composition through a film die onto a casting roller, further
wherein the surface of the casting roller comprises the mold.
[0014] In further exemplary methods of making a polishing pad as
described above, the mold comprises a three-dimensional pattern,
and the first major surface comprises a multiplicity of polishing
elements corresponding to an impression of the three-dimensional
pattern, wherein the plurality of polishing elements extend
outwardly from the first major side along a first direction
substantially normal to the first major side, further wherein the
polishing elements are integrally formed with the sheet and
laterally connected so as to restrict lateral movement of the
polishing elements with respect to one or more of the other
polishing elements, but remaining moveable in an axis substantially
normal to a polishing surface of the polishing elements.
[0015] In some exemplary methods of making a polishing pad as
described above, the method further includes affixing a compliant
layer to the second major side. In further exemplary embodiments,
the method further includes affixing a polishing composition
distribution layer covering at least a portion of the first major
side. In certain exemplary embodiments, the method additionally
includes forming a pattern with the polishing elements on the first
major side. In certain exemplary embodiments, forming a pattern
comprises reaction injection molding the polishing elements in the
pattern, extrusion molding the polishing elements in the pattern,
compression molding the polishing elements in the pattern,
arranging the polishing elements within a template corresponding to
the pattern, or arranging the polishing elements on the support
layer in the pattern. In some particular exemplary embodiments,
bonding the polishing elements to the support layer comprises
thermal bonding, ultrasonic bonding, actinic radiation bonding,
adhesive bonding, and combinations thereof.
[0016] In certain presently preferred exemplary embodiments, at
least a portion of the polishing elements comprise porous polishing
elements. In some exemplary embodiments, at least some of the
polishing elements comprise substantially non-porous polishing
elements. In some particular exemplary embodiments, the porous
polishing elements are formed by injection molding of a gas
saturated polymer melt, injection molding of a reactive mixture
that evolves a gas upon reaction to form a polymer, injection
molding of a mixture comprising a polymer dissolved in a
supercritical gas, injection molding of a mixture of incompatible
polymers in a solvent, injection molding of porous thermoset
particulates dispersed in a thermoplastic polymer, injection
molding of a mixture comprising microballoons, and combinations
thereof. In additional exemplary embodiments, the pores are formed
by reaction injection molding, gas dispersion foaming, and
combinations thereof.
[0017] Exemplary embodiments of polishing pads according to the
present disclosure have various features and characteristics that
enable their use in a variety of polishing applications. In some
presently preferred embodiments, polishing pads of the present
disclosure may be particularly well suited for chemical mechanical
planarization (CMP) of wafers used in manufacturing integrated
circuits and semiconductor devices. In certain exemplary
embodiments, the polishing pad described in this disclosure may
provide some or all of the following advantages.
[0018] For example, in some exemplary embodiments, a polishing pad
according to exemplary embodiments of the present disclosure may
act to better retain a working liquid used in the CMP process at
the interface between the polishing surface of the pad and the
substrate surface being polished, thereby improving the
effectiveness of the working liquid in augmenting polishing. In
other exemplary embodiments, a polishing pad according to the
present disclosure may reduce or eliminate dishing and/or edge
erosion of the wafer surface during polishing.
[0019] In further exemplary embodiments, use of a polishing pad
with porous elements according to exemplary embodiments of the
present disclosure may permit processing of larger diameter wafers
while maintaining the required degree of surface uniformity to
obtain high chip yield, processing of more wafers before
conditioning of the pad surface is needed in order to maintain
polishing uniformity of the wafer surfaces, or reducing process
time and wear on the pad conditioner. In certain embodiments, CMP
pads with porous polishing elements may also offer the benefits and
advantages of conventional CMP pads having surface textures such as
grooves, but may be manufactured more reproducibly at a lower cost.
In additional embodiments, bonding of the polishing elements to the
support layer may eliminate the need to use a guide plate or an
adhesive to affix the elements to the support layer.
[0020] Various aspects and advantages of exemplary embodiments of
the disclosure have been summarized. The above Summary is not
intended to describe each illustrated embodiment or every
implementation of the present certain exemplary embodiments of the
present disclosure. The Drawings and the Detailed Description that
follow more particularly exemplify certain preferred embodiments
using the principles disclosed herein.
BRIEF DESCRIPTION OF DRAWINGS
[0021] Exemplary embodiments of the present disclosure are further
described with reference to the appended figures, wherein:
[0022] FIG. 1 is a cross-sectional side view of a polishing pad
including a sheet of integrally formed polishing elements according
to one exemplary embodiment of the present disclosure.
[0023] FIG. 2 is a cross-sectional side view of a polishing pad
including a plurality of polishing elements bonded to a support
layer according to another exemplary embodiment of the present
disclosure.
[0024] FIG. 3A is a perspective view of a polishing pad with
polishing elements arranged in a pattern according to an exemplary
embodiment of the present disclosure.
[0025] FIG. 3B is a top view of a polishing pad with polishing
elements arranged in a pattern according to another exemplary
embodiment of the present disclosure.
[0026] Like reference numerals in the drawings indicate like
elements. The drawings herein are not drawn to scale, and in the
drawings the components of the polishing pads are sized to
emphasize selected features.
DETAILED DESCRIPTION
[0027] In a typical CMP slurry process for wafer polishing, a wafer
possessing a characteristic topography is put in contact with a
polishing pad and a polishing solution containing an abrasive and a
polishing chemistry. If the polishing pad is compliant, the
phenomenon of dishing and erosion may occur due to the soft pad
polishing the low areas on the wafer at the same rate as the raised
areas. If the polishing pad is rigid, dishing and erosion may be
greatly reduced; however, even though rigid polishing pads may
advantageously yield good within die planarization uniformity, they
may also disadvantageously yield poor within wafer uniformity, due
to a rebound effect which occurs on the wafer perimeter. This
rebound effect results in poor edge yield and a narrow CMP
polishing process window. In addition, it may be difficult to
develop a stable polishing process with a rigid polishing pad,
because such pads are sensitive to different wafer topographies,
and are completely dependent upon use of a pad conditioner to
create an optimal polishing texture which holds the polishing
solution and interfaces with the wafer.
[0028] Thus, in some exemplary embodiments, the present disclosure
is directed to improved CMP polishing pads which, in various
embodiments, combine some of the advantageous characteristics of
both compliant and rigid polishing pads, while eliminating or
reducing some of the disadvantageous characteristics of the
respective pads.
[0029] Various exemplary embodiments of the disclosure will now be
described with particular reference to the Drawings. Exemplary
embodiments of the present disclosure may take on various
modifications and alterations without departing from the spirit and
scope of the disclosure. Accordingly, it is to be understood that
the embodiments of the present disclosure are not to be limited to
the following described exemplary embodiments, but are to be
controlled by the limitations set forth in the claims and any
equivalents thereof.
[0030] Referring to FIG. 1, in one exemplary embodiment the present
disclosure provides a polishing pad 2 comprising a sheet 13' having
a first major side 32 and a second major side 33 opposite the first
major side 32, and a plurality of polishing elements 4 extending
outwardly from the first major side 32 along a first direction
substantially normal to the first major side 32 as shown in FIG. 1,
wherein at least a portion of the polishing elements 4 are
integrally formed with the sheet 13' and laterally connected so as
to restrict lateral movement of the polishing elements 4 with
respect to one or more of the other polishing elements 4, but
remaining moveable in an axis substantially normal to a polishing
surface 14 of the polishing elements 4, wherein at least a portion
of the plurality of polishing elements 4 comprise an organic
particulate filler 15 in a continuous polymer phase.
[0031] In the particular exemplary embodiment illustrated by FIG.
1, sheet 13' is affixed to an optional compliant layer 16
positioned on a side opposite the plurality of polishing elements 4
(i.e. on second major side 33). Furthermore, an optional adhesive
layer 12 is shown at an interface between compliant layer 16 and
the sheet 13'. Optional adhesive layer 12 may be used to affix the
second major side 33 of the sheet 13' to the compliant layer 16.
Additionally, an optional pressure sensitive adhesive layer 18,
affixed to the compliant layer 16 opposite the plurality of
polishing elements 4, may be used to temporarily (e.g. removably)
secure the polishing pad 2 to a polishing platen (not shown in FIG.
1) of a CMP polishing apparatus (not shown in FIG. 1).
[0032] In some exemplary embodiments, the polishing pad 2 further
includes an optional polishing composition distribution layer 8
covering at least a portion of the first major side, as shown in
FIG. 1. During a polishing process, the optional polishing
composition distribution layer 8 aids distribution of the working
liquid and/or polishing slurry to the individual polishing elements
4. A plurality of apertures 6 are provided extending through the
polishing composition distribution layer 8. A portion of each
polishing element 4 extends into a corresponding aperture 6.
[0033] In an alternate embodiment shown in FIG. 2, the present
disclosure provides a polishing pad 2' including a support layer 10
having a first major side 34 and a second major side 35 opposite
the first major side 34, and a plurality of polishing elements 4
bonded to the first major side 34 of the support layer 10, wherein
each polishing element 4 has an exposed polishing surface 14, and
wherein the polishing 4 elements extend from the first major side
34 of the support layer 10 along a first direction substantially
normal to the first major side 34, further wherein at least a
portion of the plurality of polishing elements 4 comprise an
organic particulate filler 15 in a continuous polymer phase.
[0034] In some exemplary embodiments of a polishing pad 2', each
polishing element 4 is affixed to the first major side 34 by direct
thermal bonding to the support layer 10, or by using an adhesive
(not shown in FIG. 2) to bond the polishing elements 4 to the
support layer 10. In certain exemplary embodiments, the polishing
pad further includes an optional guide plate 28 opposite the
support layer 10 on the first major side 34, wherein the guide
plate 28 comprises a plurality of apertures 6 extending through the
guide plate 28, and further wherein at least a portion of each
polishing element 4 extends into a corresponding aperture 6. In
certain exemplary embodiments, a portion of each polishing element
4 passes through the corresponding aperture 6. In some particular
exemplary embodiments, each polishing element has a flange 17, and
each flange 17 has a perimeter greater than the perimeter of the
corresponding aperture 6, as shown in FIG. 2.
[0035] In the particular exemplary embodiment illustrated by FIG.
2, support layer 10 is affixed to an optional compliant layer 16
positioned on the second major side 35 of the support layer 10
opposite the plurality of polishing elements 4 affixed to the first
major side 34 of the support layer 10. Furthermore, an optional
adhesive layer 12 is shown at an interface between compliant layer
16 and the support layer 10. Optional adhesive layer 12 may be used
to affix the second major side 35 of the support layer 10 to the
compliant layer 16. Additionally, an optional pressure sensitive
adhesive layer 18, affixed to the compliant layer 16 opposite the
plurality of polishing elements 4, may be used to temporarily (e.g.
removably) secure the polishing pad 2' to a polishing platen (not
shown in FIG. 2) of a CMP polishing apparatus (not shown in FIG.
2).
[0036] An optional guide plate 28 is also shown in the exemplary
embodiment of FIG. 2. The optional guide plate 28, which may also
serve as an alignment template for arranging the plurality of
polishing elements 4 on the first major side of support layer 10,
is not generally required in order to produce polishing pads 2'
according to the present disclosure. In certain exemplary
embodiments, the optional guide plate 28 may be entirely eliminated
from the polishing pad, as illustrated by polishing pad 2 of FIG.
1. Such embodiments may advantageously be easier and less expensive
to fabricate than other known polishing pads comprising a
multiplicity of polishing elements.
[0037] An optional polishing composition distribution layer 8',
which may also serve as a guide plate for the polishing elements 4,
is additionally shown in FIG. 2. During a polishing process, the
optional polishing composition distribution layer 8' aids
distribution of the working liquid and/or polishing slurry to the
individual polishing elements 4. When used as a guide plate, the
polishing composition distribution layer 8 may be positioned on the
first major side 34 of the support layer 10 to facilitate
arrangement of the plurality of polishing elements 4, such that a
first major surface of the polishing composition distribution layer
8' is distal from the support layer 10, and a second major surface
of the polishing composition distribution layer 8' opposite the
first major surface of the polishing composition distribution layer
8' is proximate the support layer 10, as shown in FIG. 2. A
plurality of apertures 6 may also be provided extending through at
least the optional guide plate 28 (if present) and/or the optional
polishing composition distribution layer 8' (if present), as shown
in FIG. 2.
[0038] As illustrated by FIG. 2, each polishing element 4 extends
from the first major surface of the optional guide plate 28 along a
first direction substantially normal to the first major side of
support layer 10. In some embodiments shown in FIG. 2, each
polishing element 4 has a mounting flange 17, and each polishing
element 4-4' is bonded to the first major side of the support layer
10 by engagement of the corresponding flange 17 to the first major
side 34 of the support layer 10, and optionally, the second major
surface of optional polishing composition distribution layer 8' or
the optional guide plate 28. Consequently, during a polishing
process, the polishing elements 4 are free to independently undergo
displacement in a direction substantially normal to the first major
side 34 of support layer 10, while still remaining bonded to the
support layer 10, and optionally additionally affixed to the
support layer 10 by the optional polishing composition distribution
layer 8' and/or optional guide plate 28.
[0039] In such embodiments, preferably at least a portion of each
polishing element 4 extends into a corresponding aperture 6, and
more preferably, each polishing element 4 also passes through the
corresponding aperture 6 and extends outwardly from the first major
surface of the optional guide plate 28. Thus, the plurality of
apertures 6 of optional guide plate 28 and/or optional polishing
composition distribution layer 8', may also serve as a template to
guide the lateral arrangement of polishing elements 4 on the first
major side 34 of support layer 10. In other words, optional guide
plate 28 and/or optional polishing composition distribution layer
8' may be used as a template or guide to arrange the plurality of
polishing elements 4 on the first major side 34 of support layer 10
during the polishing pad fabrication process.
[0040] In the particular embodiment illustrated by FIG. 2, the
optional guide plate 28 may comprise an adhesive (not shown)
positioned at the interface between the support layer 10 and the
polishing composition distribution layer 8'. The optional guide
plate 28 may thus be used to adhere the optional polishing
composition distribution layer 8' to the support layer 10, thereby
securely affixing the plurality of polishing elements 4 to the
first major side 34 of support layer 10. However, other bonding
methods may be used, including direct thermal bonding of the
polishing elements 4 to the support layer 10 using, for example,
heat and pressure.
[0041] In a related exemplary embodiment of the polishing pad 2' of
FIG. 2, the plurality of apertures may be arranged as an array of
apertures, wherein at least a portion of the apertures 6 comprise a
main bore formed by optional polishing composition distribution
layer 8', and an undercut region formed by optional guide plate 28,
and the undercut region forms a shoulder that engages with the
corresponding polishing element flange 17, thereby securely
affixing polishing elements 4 to support layer 10 without requiring
direct bonding of the polishing elements 4 to support layer 10. In
addition, in some exemplary embodiments not illustrated by FIG. 2,
the multiplicity of polishing elements 4 may be arranged in a
pattern, for example, as a two-dimensional array of elements
arranged on a major surface of the support layer 10, or in a
template or jig used to arrange the polishing elements 4 before
bonding to the support layer 10.
[0042] In any of the embodiments of polishing pads 2-2' illustrated
in FIGS. 1-2, at least a portion of the polishing elements 4 may be
porous polishing elements, and some portion of the polishing
elements 4' may be substantially nonporous polishing elements. It
will be understood, however, that in other exemplary embodiments,
all of the polishing elements 4 may be selected to be porous
polishing elements, or all of the polishing elements may be
selected to be substantially nonporous polishing elements 4'. In
some exemplary embodiments, at least one of the polishing elements
is a porous polishing element, wherein each porous polishing
element includes a plurality of pores. In certain exemplary
embodiments, substantially all of the polishing elements are porous
polishing elements. In some particular exemplary embodiments, the
pores are distributed throughout substantially the entire porous
polishing element.
[0043] Suitable porous polishing elements are disclosed in PCT
International Pub. No. WO 2009/158665, the entire disclosure of
which is incorporated herein by reference. In certain presently
preferred embodiments, the plurality of pores is created by at
least partially removing at least a portion of the organic
particulate filler 15 from at least a portion of the polishing
elements 4 of polishing pad 2-2', thereby leaving a void or pore
volume corresponding to the volume previously occupied by the
organic particulate filler 15. In some exemplary embodiments, the
organic particulate filler 15 may be soluble in a solvent in which
the remaining polymer phase of the polishing element 4 is
substantially insoluble or only partially soluble.
[0044] In some exemplary embodiments, the organic particulate
filler 15 comprises a water soluble, water swellable or hydrophilic
polymer, and water or an aqueous solvent is used to dissolve and
thereby remove at least a portion of the organic particulate filler
15 from one or more polishing elements 4, thereby creating one or
more porous polishing elements. In certain exemplary embodiments,
the aqueous solvent is selected to be the working liquid used in a
chemical mechanical polishing process, and this working liquid is
used to dissolve and thereby remove at least a portion of the
organic particulate filler 15 from one or more polishing elements
4, thereby creating one or more porous polishing elements.
[0045] In the particular embodiment illustrated by FIGS. 1-2, two
porous polishing elements 4 are shown along with one substantially
nonporous polishing element 4'. However, it will be understood that
any number of polishing elements 4 may be used, and that any number
of polishing elements 4 may be selected to be porous polishing
elements 4 or substantially nonporous polishing elements 4'.
[0046] In some presently preferred embodiments, at least a portion
of the polishing elements 4 are porous polishing elements, which in
certain embodiments at least have a porous polishing surface (14 in
FIGS. 1-2), which may make sliding or rotational contact with a
substrate (not shown in FIG. 1) to be polished. Referring again to
FIGS. 1-2, the polishing surface 14 of polishing elements 4 may be
a substantially flat surface, or may be textured. In certain
presently preferred embodiments, at least the polishing surface of
each polishing element 4 is made porous, for example with
microscopic surface openings or pores 15, which may take the form
of orifices, passageways, grooves, channels, and the like. Such
pores 15 at the polishing surface may act to facilitate
distributing and maintaining a polishing composition (e.g., a
working liquid and/or abrasive polishing slurry not shown in the
figures) at the interface between a substrate (not shown) and the
corresponding porous polishing elements.
[0047] In certain exemplary embodiments, the polishing surface 14
comprises pores 15 that are generally cylindrical capillaries. The
pores 15 may extend from the polishing surface 14 into the
polishing element 4. In a related embodiment, the polishing surface
comprises pores 15 that are generally cylindrical capillaries
extending from the polishing surface 14 into the porous polishing
element 4. The pores need not be cylindrical, and other pore
geometries are possible, for example, conical, rectangular,
pyramidal, and the like. The characteristic dimensions of the pores
can, in general, be specified as a depth, along with a width (or
diameter), and a length. The characteristic pore dimensions may
range from about 25 .mu.m to about 6,500 .mu.m in depth, from about
5 .mu.m to about 1000 .mu.m in width (or diameter), and from about
10 .mu.m to about 2,000 .mu.m in length.
[0048] In some exemplary embodiments, the porous polishing elements
may not have a porous polishing surface 14, but in these and other
exemplary embodiments, pores 15 may be distributed throughout
substantially the entire porous polishing element 4. Such porous
polishing elements may be useful as compliant polishing elements
exhibiting some of the advantageous characteristics of a compliant
polishing pad. In certain presently preferred embodiments, the
polishing elements 4 may comprise a plurality of pores distributed
throughout substantially the entire polishing element 4 in the form
of a porous foam. The foam may be a closed cell foam, or an open
cell foam. Closed cell foams may be preferred in some embodiments.
Preferably, the plurality of pores 15 in the foam exhibits a
unimodal distribution of pore size, for example, pore diameter.
[0049] In some particular exemplary embodiments, the plurality of
pores exhibits a mean pore size of at least about 1 nanometer (nm),
at least about 100 nm, at least about 500 nm, or at least about 1
.mu.m. In other exemplary embodiments, the plurality of pores
exhibits a mean pore size of at most about 300 .mu.m, at most about
100 .mu.m, at most about 50 .mu.m, at most about 10 .mu.m, or at
most about 1 .mu.m. In certain presently preferred embodiments, the
plurality of pores exhibits a mean pore size from about 1 nm to
about 300 .mu.m, about 0.5 .mu.m to about 100 .mu.m, about 1 .mu.m
to about 100 .mu.m, or about 2 .mu.m to about 50 .mu.m.
[0050] In additional exemplary embodiments of polishing pads 2-2'
including substantially nonporous polishing elements 4' as
described above, at least one of the nonporous polishing elements
4' is preferably a transparent polishing element. In some exemplary
embodiments, the sheet 13' or support layer 10, the optional guide
plate 28, the optional polishing composition distribution layer
8-8', the optional compliant layer 16, the optional adhesive 12,
layer, at least one substantially nonporous polishing elements 4',
or a combination thereof is transparent. In certain exemplary
embodiments illustrated in FIG. 1, at least one transparent
nonporous polishing element 4' is affixed to a transparent portion
of the first major side 32 of sheet 13', e.g. using direct thermal
bonding or with an adhesive (not shown in FIG. 1).
[0051] Furthermore, it will be understood that the polishing pads
2-2' need not comprise only substantially identical polishing
elements 4. Thus, for example, any combination or arrangement of
porous polishing elements and non-porous polishing elements may
make up the plurality of polishing elements 4. It will also be
understood that any number, combination or arrangement of porous
polishing elements and substantially nonporous polishing elements
4' may be used advantageously in certain embodiments to form a
polishing pad having a plurality of polishing elements 4.
[0052] In some exemplary embodiments, the polishing elements (4-4'
in FIGS. 1-2) may be distributed on the first major side of sheet
13' (FIG. 1) or support layer 10 (FIG. 2) in a wide variety of
patterns, depending on the intended application, and the patterns
may be regular or irregular. Thus, in some exemplary embodiments of
a polishing pad 2-2', the plurality of polishing elements 4 may be
arranged in a pre-determined regular pattern, for example, on a
major surface of the support layer 10, or in a template or jig (not
shown in the FIGs.) used to arrange the polishing elements before
bonding to the support layer 10. After arranging the plurality of
polishing elements 4 in the pattern using the template or jig, the
first major side 34 of the support layer 10 may be contacted with
and bonded to the plurality of polishing elements 4, for example,
by direct thermal bonding to the support layer 10, or by using an
adhesive, or other bonding material.
[0053] The polishing elements may reside on substantially the
entire surface of the sheet 13' or support layer 10, or there may
be regions of the sheet 13' or support layer 10 that include no
polishing elements. In some embodiments, the polishing elements
have an average surface coverage of the support layer of at least
30%, at least 40%, or at least 50%. In further embodiments, the
polishing elements have an average surface coverage of the support
layer of at most about 80%, at most about 70%, or at most about 60%
of the total area of the major surface of the support layer, as
determined by the number of polishing elements, the cross-sectional
area of each polishing element, and the cross-sectional area of the
polishing pad.
[0054] In an exemplary embodiment of a presently preferred
polishing pad 2 illustrated by FIG. 3A-3B, the polishing elements 4
are integrally formed with sheet 13' and arranged in a
two-dimensional array pattern on the first major side 32 of sheet
13'. It will be understood that any of the optional layers (e.g.
the optional polishing composition distribution layer 8, the
optional adhesive 12, the optional compliant layer 16, the optional
pressure sensitive adhesive layer 18, and the at least one
substantially nonporous/transparent polishing element 4'), as
described above as suitable for use in a polishing pad 2 may be
combined to form the polishing pad shown in FIG. 3A-3B.
[0055] FIG. 3A illustrates one particular shape of a polishing
element 4. It will be understood that the polishing elements 4 may
be formed in virtually any shape, and that a plurality of polishing
elements 4 having two or more different shapes may be
advantageously used and optionally arranged in a pattern to form a
polishing pad 2-2' as described above. It will be further
understood that the same shape or a different shape may be used to
produce a porous polishing element or alternatively, a
substantially nonporous polishing element.
[0056] In some exemplary embodiments, the cross-sectional shape of
the polishing elements 4, taken through a polishing element 4 in a
direction generally parallel to the polishing surface 14, may vary
widely depending on the intended application. Although FIG. 3A
shows a generally cylindrical polishing element 4 having a
generally circular cross section, other cross-sectional shapes are
possible and may be desirable in certain embodiments. Thus, in
further exemplary embodiments of polishing pads 2-2' including
polishing elements 4-4' as previously described, the polishing
elements are selected to have a cross-section, taken in the first
direction, selected from circular, elliptical, triangular, square,
rectangular, and trapezoidal, and combinations thereof.
[0057] For generally cylindrical polishing elements 4 having a
circular cross section as shown in FIGS. 3A-3B, the cross-sectional
diameter of the polishing element 4 in a direction generally
parallel to the polishing surface 14 is, in some embodiments, at
least about 50 .mu.m, more preferably at least about 1 mm, still
more preferably at least about 5 mm. In certain embodiments, the
cross-sectional diameter of the polishing element 4 in a direction
generally parallel to the polishing surface 14 is at most about 20
mm, more preferably at most about 15 mm, still more preferably at
most about 12 mm. In some embodiments, the diameter of the
polishing element, taken at the polishing surface 14, may be from
about 50 .mu.m to about 20 mm, in certain embodiments the diameter
is from about 1 mm to about 15 mm, and in other embodiments the
cross-sectional diameter is from about 5 mm to about 12 mm.
[0058] In additional exemplary embodiments of polishing pads 2-2',
the polishing elements 4 may be characterized by a characteristic
dimension in terms of a height, width, and/or length. In certain
exemplary embodiments, the characteristic dimension may be selected
to be at least about 50 .mu.m, more preferably at least about 1 mm,
still more preferably at least about 5 mm. In certain embodiments,
the cross-sectional diameter of the polishing element 4 in a
direction generally parallel to the polishing surface 14 is at most
about 20 mm, more preferably at most about 15 mm, still more
preferably at most about 12 mm. In additional exemplary
embodiments, the polishing elements are characterized by at least
one of a height from 250 to 2,500 .mu.m, a width 1 mm to 50 mm, a
length from 5 mm to 50 mm, or a diameter of from 1 mm to 50 mm. In
certain exemplary embodiments, one or more of the polishing
elements 4-4' may be hollow.
[0059] In other exemplary embodiments, the cross-sectional area of
each polishing element 4 in a direction generally parallel to the
polishing surface 14, may be at least about 1 mm.sup.2, in other
embodiments at least about 10 mm.sup.2, and in still other
embodiments at least about or 20 mm.sup.2. In other exemplary
embodiments, the cross-sectional area of each polishing element 4
in a direction generally parallel to the polishing surface 14, may
be at most about 1,000 mm.sup.2, in other embodiments at most about
500 mm.sup.2, and in still other embodiments at most about 250
mm.sup.2.
[0060] The cross-sectional area of the polishing pad in a direction
generally parallel to a major surface of the polishing pad may, in
some exemplary embodiments, range from about 100 cm.sup.2 to about
300,000 cm.sup.2, in other embodiments from about 1,000 cm.sup.2 to
about 100,000 cm.sup.2, and in yet other embodiments, from about
2,000 cm.sup.2 to about 50,000 cm.sup.2.
[0061] Prior to the first use of the polishing pad (2 in FIG. 1, 2'
in FIG. 2) in a polishing operation, in some exemplary embodiments,
each polishing element (4-4' in FIGS. 1-2) extends along the first
direction substantially normal to the first major side of the
support layer (10 in FIGS. 1-2). In certain exemplary embodiments,
the polishing elements extend along the first direction at least
about 0 mm, at least about 0.1 mm, at least about 0.25 mm, at least
about 0.3 mm, or at least about 0.5 mm above a plane including the
optional polishing composition distribution layer (8 in FIG. 1, 8'
in FIG. 2) and/or optional guide plate (28 in FIG. 2). In other
exemplary embodiments, the polishing elements extend along the
first direction at most about 10 mm, at most about 7.5 mm, at most
about 5 mm, at most about 3 mm, at most about 2 mm, or at most
about 1 mm above a plane including the optional polishing
composition distribution layer (8 in FIG. 1, 8' in FIG. 2) and/or
optional guide plate (28 in FIG. 2).
[0062] In other exemplary embodiments (not shown in the FIGs.), the
polishing surfaces of the polishing elements may be made flush with
the exposed major surface of the optional polishing composition
distribution layer. Tn other exemplary embodiments, the polishing
surfaces of the polishing elements may be made recessed below the
exposed major surface of the optional polishing composition
distribution layer, and subsequently made flush with, or made to
extend beyond, the exposed major surface of the optional polishing
composition distribution layer, for example, by removal of a
portion of the optional polishing composition distribution layer.
Such embodiments may be advantageously used with polishing
composition distribution layers that are selected to be abraded or
eroded during the polishing process or in optional conditioning
processes applied to the polishing pad before, during, or after
contact with a workpiece.
[0063] In further exemplary embodiments, each polishing element 44'
extends along the first direction at least about 0.25 mm, at least
about 0.3 mm, or at least about 0.5 mm above a plane including the
sheet 13' (FIG. 1) or support layer 10 (FIG. 2). In additional
exemplary embodiments, the height of the polishing surface (14 in
FIGS. 1-2) above the base or bottom of the polishing element, that
is, the height (H) of the polishing element may be 0.25 mm, 0.5 mm,
1.0 mm, 1.5 mm, 2.0 mm, 2.5 mm, 3.0 mm, 5.0 mm, 10 mm or more,
depending on the polishing composition used and the material
selected for the polishing elements.
[0064] Referring again to FIGS. 1-2, the depth and spacing of the
apertures (6 in FIG. 1-2) throughout the optional polishing
composition distribution layer (8 in FIG. 1, 8' in FIG. 2) and/or
optional guide plate 28 (FIG. 2) may be varied as necessary for a
specific CMP process. In some embodiments, the polishing elements
(4-4' in FIGS. 1-2) are each maintained substantially in planar
orientation with respect to one other and the polishing composition
distribution layer (8 in FIG. 1, 28 in FIG. 2) and guide plate 31,
and project above the surface of the optional polishing composition
distribution layer (8 in FIG. 1, 8' in FIG. 2) and/or optional
guide plate 28.
[0065] In some exemplary embodiments, the void volume created by
the extension of the polishing elements 4 above any optional guide
plate (28 in FIG. 2) and any optional polishing composition
distribution layer (8 in FIG. 1, 8' in FIG. 2) may provide room for
distribution of a polishing composition on the surface of the
optional polishing composition distribution layer (8 in FIG. 1, 8'
in FIG. 2). The polishing elements 4 protrude above the polishing
composition distribution layer (8 in FIG. 1, 8' in FIG. 2) by an
amount that depends at least in part on the material
characteristics of the polishing elements and the desired flow of
polishing composition (working liquid and or abrasive slurry) over
the surface of the polishing composition distribution layer (8 in
FIG. 1, 8' in FIG. 2).
[0066] In another alternative exemplary embodiment (not illustrated
in the FIGs.), the present disclosure provides a textured polishing
pad including an organic particulate filler and a second continuous
polymer phase, wherein the polishing pad has a first major side and
a second major side opposite the first major side, and further
wherein at least one of the first and second major sides comprises
a multiplicity of grooves extending into the side. In certain
exemplary embodiments, the grooves have a depth of from about 1
micrometer (.mu.m) to about 5,000 .mu.m. In further exemplary
embodiments, the polishing pad has a circular cross-section in a
direction substantially normal to the first and second sides,
wherein the circle defines a radial direction, and further wherein
the plurality of grooves are circular, concentric, and spaced apart
in the radial direction.
[0067] In other exemplary embodiments (not illustrated in the
FIGs.), the polishing surface of the textured polishing pad
comprises pores in the form of a plurality of channels, wherein
each channel extends across at least a portion of the polishing
surface, preferably in a direction generally parallel to the
polishing surface. Preferably, each channel is a circular channel
that extends radially around a circumference of the polishing
surface in a direction generally parallel to the polishing surface.
In other embodiments, the plurality of channels form a series of
radially spaced concentric circular grooves in the polishing
surface. In other exemplary embodiments (not illustrated), the
pores may take the form of a two-dimensional array of channels in
which each channel extends across only a portion of the polishing
surface.
[0068] In further exemplary embodiments (not illustrated in the
FIGs.), the channels may have virtually any shape, for example,
cylindrical, triangular, rectangular, trapezoidal, hemispherical,
and combinations thereof. In some exemplary embodiments, the depth
of each channel in a direction substantially normal to the
polishing surface of the polishing elements is selected to be in
the range of at least about 10 .mu.m, 25 .mu.m, 50 .mu.m, 100
.mu.m; to about 10,000 .mu.m, 7,500 .mu.m, 5,000 .mu.m, 2,500
.mu.m, 1,000 .mu.m. In other exemplary embodiments, the
cross-sectional area of each channel in a direction substantially
parallel to the polishing surface of the polishing elements is
selected to be in the range from about 75 square micrometers
(.mu.m.sup.2) to about 3.times.10.sup.6 .mu.m.sup.2.
[0069] The composition of the polishing pads as described above
includes a continuous polymeric phase filled with a non-interactive
organic filler. The continuous polymeric phase is characterized as
being a thermoplastic or thermoset elastomer, while the dispersed
phase is characterized as a thermoplastic or thermoset polymer. In
some exemplary embodiments of polishing pads as described above, at
least a portion of the polishing surface comprises a thermoplastic
polyurethane, an acrylated polyurethane, an epoxidized
polyurethane, an epoxidized rubber, a vinyl resin, a
cyclopentadiene resin, a vinyl ether resin, and combinations
thereof. In some exemplary embodiments of polishing pads including
a plurality of polishing elements 4, at least some of the polishing
elements comprise, as a continuous polymer phase, a thermoplastic
polyurethane, an acrylated polyurethane, an epoxidized
polyurethane, an epoxidized rubber, a vinyl resin, a
cyclopentadiene resin, a vinyl ether resin, a polyacrylate, or
combinations thereof.
[0070] In certain exemplary embodiments, the organic particulate
filler comprises at least one of a thermoplastic polymer or a
thermoset polymer. In some exemplary embodiments, the organic
particulate filler comprises at least one of a polyolefin, a cyclic
polyolefin, or a polyolefinic thermoplastic elastomer. In some
particular exemplary embodiments, the polyolefin is selected from
polyethylene, polypropylene, polybutylene, polyisobutylene,
polyoctene, copolymers thereof, and combinations thereof. In other
exemplary embodiments, the organic particulate filler comprises a
water soluble or water swellable polymer, such as, for example,
polyvinyl alcohol, poly(ethylene oxide), poly (vinyl alcohol), poly
(vinyl pyrollidone), polyacrylic acid, poly(meth)acrylic acid,
combinations thereof, and the like.
[0071] In further exemplary embodiments, the organic particulate
filler comprises from about 5% to about 90% by weight of each
polishing element. In additional exemplary embodiments, the organic
particulate filler is characterized by at least one of a length
from 5 to 5,000 micrometers, a width from 5 to 250 micrometers, an
equivalent spherical diameter of from 5 to 100 micrometers, or a
combination thereof.
[0072] The polishing elements may also comprise a reinforced
polymer or other composite material, including, for example, metal
particulates, ceramic particulates, polymeric particulates, fibers,
combinations thereof, and the like. In certain embodiments,
polishing elements may be made electrically and/or thermally
conductive by including therein fillers such as, carbon, graphite,
metals or combinations thereof. In other embodiments, electrically
conductive polymers such as, for example, polyanilines (PANI) sold
under the trade designation ORMECOM (available from Ormecon Chemie,
Ammersbek, Germany) may be used, with or without the electrically
or thermally conductive fillers referenced above.
[0073] In some exemplary embodiments, to generate the polishing
elements, a continuous phase polymer resin precursor system may be
milled with a micronized organic particulate powder to generate a
reactive slurry containing the dispersed organic particulate phase.
The filled reactive slurry may then be cast directly into a mold or
b-staged and molded under pressure to generate a patterned surface
comprising integrally molded polishing elements. Upon at least
partially curing the polymer resin precursor, a sheet having the
desired pattern of polishing elements may be obtained, and the
sheet may subsequently be secured to a compliant support layer to
form a compliant polishing pad. Alternatively the compliant support
layer may be laminated to the integrally molded polishing surface
during film casting or molding operations. A pressure sensitive
adhesive my also be used to adhere the bottom surface of the
compliant material to the surface of the polishing plate used in
semiconductor polishing.
[0074] In any of the exemplary embodiments of polishing pads as
described above, the polishing surface is formed by a phase
separated polymer blend comprising a continuous polymer phase and
an organic particulate filler immiscible in the continuous polymer
phase at room temperature. The size of the dispersed organic
particulate phase can be controlled by controlling the particle
size of the dispersed organic particulates, for example, by
controlling the milling conditions and/or duration. Polymeric films
generated from these type of immiscible blend systems
characteristically shed the dispersed organic particulate phase
when subjected to fracture or scoring. Therefore if a pad surface
is generated from this type of polymeric blend, the surface would
be characterized has having porosity resulting from the shedding or
release of the dispersed organic particulate phase.
[0075] In other exemplary embodiments, a plurality of pores is
created in at least some of the polishing elements by at least
partially removing at least a portion of the organic particulate
filler 15 from at least a portion of the polishing elements 4 of
polishing pad 2-2', thereby leaving a void or pore volume
corresponding to the volume previously occupied by the organic
particulate filler 15. In some exemplary embodiments, the organic
particulate filler may be soluble in a solvent in which the first
continuous polymer phase 13 is substantially insoluble or only
partially soluble.
[0076] In some exemplary embodiments, the organic particulate
filler comprises a water soluble, water swellable or hydrophilic
thermoplastic polymer, and water or an aqueous solvent is used to
dissolve and thereby remove at least a portion of the organic
particulate filler 15 from one or more polishing elements 4,
thereby creating one or more porous polishing elements. Suitable
water soluble polymers include poly(ethylene oxide), poly (vinyl
alcohol), poly (vinyl pyrollidone), polyacrylic acid,
poly(meth)acrylic acid, copolymers thereof with other monomers, and
combinations thereof.
[0077] In certain exemplary embodiments, the aqueous solvent is
selected to be the working liquid used in a chemical mechanical
polishing process, and this working liquid is used to dissolve and
thereby remove at least a portion of the organic particulate filler
15 from one or more polishing elements 4, thereby creating one or
more porous polishing elements.
[0078] In further exemplary embodiments of polishing pads as
described above, the organic particulate filler comprises from
about 1%, 2.5%, 5%, or 10%; to about 50%, 60%, 70%, 80%, or 90% by
weight of each polishing element. In certain exemplary embodiments,
the organic particulate filler is characterized by at least one of
a length from 5 to 5,000 .mu.m, a width from 5 to 250 .mu.m, an
equivalent spherical diameter of from 5 to 100 .mu.m, or a
combination thereof. Preferable, the organic particulate filler has
a substantially uniform spherical shape, and exhibits a median
diameter of at least 5 .mu.m, 10 .mu.m, 20 .mu.m, 30 .mu.m, 40
.mu.m, 50 .mu.m; and at most 200 .mu.m, 150 .mu.m, 100 .mu.m, 90
.mu.m, 80 .mu.m, 70 .mu.m, or 60 .mu.m.
[0079] In further exemplary embodiments of any of the polishing
pads described above, the sheet 13', support layer 10 or textured
polishing pad may be substantially incompressible, such as a rigid
film or other hard substrate, but is preferably compressible to
provide a positive pressure directed toward the polishing surface.
In some exemplary embodiments, the sheet or support layer may
comprise a flexible and compliant material, such as a compliant
rubber or polymer. In other exemplary embodiments, the sheet,
support layer or pad is preferably made of a compressible polymeric
material, foamed polymeric materials being preferred. In certain
embodiments, closed cell foams may be preferred, although in other
embodiments, and open cell foam may be used. In additional
exemplary embodiments, the polishing elements may be formed with
the support layer as a unitary sheet of polishing elements affixed
to the support layer, which may be a compressible or compliant
support layer.
[0080] The sheet or support layer is preferably liquid impermeable,
to prevent penetration or permeation of a working liquid into or
through the support layer. However, in some embodiments, the sheet
or support layer may comprise liquid permeable materials, alone or
in combination with an optional barrier that acts to prevent or
inhibit liquid penetration or permeation through the support layer.
Furthermore, in other embodiments, a porous sheet or support layer
may be used advantageously, for example, to retain a working liquid
(e.g. a polishing slurry) at the interface between the polishing
pad and a workpiece during polishing.
[0081] In certain exemplary embodiments, the sheet or support layer
may comprise a polymeric material selected from silicone, natural
rubber, styrene-butadiene rubber, neoprene, polyurethane,
polyester, polyethylene, and combinations thereof. The sheet or
support layer may further comprise a wide variety of additional
materials, such as fillers, particulates, fibers, reinforcing
agents, and the like.
[0082] Polyurethanes have been found to be particularly useful
sheet or support layer materials, with thermoplastic polyurethanes
(TPUs) being particularly preferred. In some presently preferred
embodiments, the support layer is a film comprising one or more
TPU, for example, an ESTANE TPU (available from Lubrizol Advanced
Materials, Inc., Cleveland, Ohio), a TEXIN or DESMOPAN TPU
(available from Bayer Material Science, Pittsburgh, Pa.), a
PELLETHANE TPU (available from Dow Chemical Company, Midland,
Mich.), and the like.
[0083] In some exemplary embodiments, the polishing pad further
comprises a compliant layer 16 affixed to the support layer
opposite the polishing elements. The compliant layer may be affixed
to the support layer by any means of bonding surfaces, but
preferably, an adhesive layer positioned at an interface between
the compliant layer and the support layer is used to affix the
support layer to the compliant layer opposite the polishing
elements.
[0084] In certain embodiments, the compliant layer is preferably
compressible to provide a positive pressure directing the polishing
surfaces of the polishing elements toward a workpiece during
polishing. In some exemplary embodiments, the support layer may
comprise a flexible and compliant material, such as a compliant
rubber or polymer. In other exemplary embodiments, the support
layer is preferably made of a compressible polymeric material,
foamed polymeric materials being preferred. In certain embodiments,
closed cell foams may be preferred, although in other embodiments,
and open cell foam may be used.
[0085] In some particular embodiments, the compliant layer may
comprise a polymeric material selected from silicone, natural
rubber, styrene-butadiene rubber, neoprene, polyurethane,
polyethylene and its copolymers, and combinations thereof. The
compliant layer may further comprise a wide variety of additional
materials, such as fillers, particulates, fibers, reinforcing
agents, and the like. The compliant layer is preferably liquid
impermeable (although permeable materials may be used in
combination with an optional barrier to prevent or inhibit liquid
penetration into the compliant layer.
[0086] Presently preferred polymeric materials for use in the
compliant layer are polyurethanes, with TPUs being particularly
preferred. Suitable polyurethanes include, for example, those
available under the trade designation PORON from Rogers Corp.,
Rogers, Conn., as well as those available under the trade
designation PELLETHANE from Dow Chemical, Midland, Mich.,
particularly PELLETHANE 2102-65D. Other suitable materials include
polyethylene terepthalates (PET), such as, for example biaxially
oriented PET widely available under the trade designation MYLAR, as
well as bonded rubber sheets (e.g. rubber sheets available from
Rubberite Cypress Sponge Rubber Products, Inc., Santa Ana, Calif.,
under the trade designation BONDTEX).
[0087] In some exemplary embodiments, polishing pads 2-2' according
to the present disclosure may have certain advantages when used in
a CMP process, for example, improved within wafer polishing
uniformity, a flatter polished wafer surface, an increase in edge
die yield from the wafer, and improved CMP process operating
latitude and consistency. While not wishing to be bound by any
particular theory, these advantages may result from decoupling of
the polishing surfaces of the polishing elements from the compliant
layer underlying the support layer, thereby allowing the polishing
elements to "float" in a direction substantially normal to the
polishing surface of the elements when contacting the polishing pad
to a workpiece during a polishing process.
[0088] In some embodiments of polishing pads 2', decoupling of the
polishing surfaces of the polishing elements from the compliant
underlayer may be augmented by incorporating into the polishing
article an optional guide plate 28 including a plurality of
apertures extending through the guide plate from a first major
surface to a second major surface, wherein at least a portion of
each polishing element extends into a corresponding aperture, and
wherein each polishing element extends outwardly from the second
major surface of the guide plate. The optional guide plate, which
preferably comprises a stiff or non-compliant material, may be used
to maintain the spatial orientation of polishing surface, as well
as to maintain lateral movement of the elements on the polishing
pad. In other embodiments, however, the optional guide plate is not
required, because the spatial orientation of the polishing elements
is maintained and lateral movement is prevented by bonding the
elements to the support layer, preferably by thermally bonding the
polishing elements directly to the support layer.
[0089] The optional guide plate 28 can be made of a wide variety of
materials, such as polymers, copolymers, polymer blends, polymer
composites, or combinations thereof. A rigid, non-compliant,
non-conducting and liquid impermeable polymeric material is
generally preferred, and polycarbonates have been found to be
particularly useful.
[0090] In further embodiments, polishing pads of the present
disclosure may further comprise an optional polishing composition
distribution layer 8-8' covering at least a portion of a first
major side of the sheet or support layer, as well as the first
major surface of the optional guide plate (if present). The
optional polishing composition distribution layer may be made of a
wide variety of polymeric materials. The optional polishing
composition distribution layer may, in some embodiments, comprise
at least one hydrophilic polymer. Preferred hydrophilic polymers
include polyurethanes, polyacrylates, polyvinyl alcohols,
polyoxymethylenes, and combinations thereof. In one particular
embodiment, the polishing composition layer may comprise a hydrogel
material, such as, for example a hydrophilic polyurethane or
polyacrylate, that can absorb water, preferably in a range of about
5 to about 60 percent by weight, to provide a lubricious surface
during polishing operations.
[0091] In additional exemplary embodiments, the optional polishing
composition distribution layer comprises a compliant material, for
example, a porous polymer or foam, to provide a positive pressure
directed toward to substrate during polishing operations when the
polishing composition distribution layer is compressed. In certain
exemplary embodiments, the compliance of the polishing composition
distribution layer is selected to be less than the compliance of
the optional compliant layer. Porous or foamed materials with open
or closed cells may be preferred compliant materials for use in an
optional polishing composition distribution layer in certain
embodiments. In some particular embodiments, the optional polishing
composition distribution layer has between about 10 and about 90
percent porosity.
[0092] In certain exemplary embodiments, the compliant layer is
affixed to the second major side by an adhesive layer at an
interface between the compliant layer and the second major
side.
[0093] In further exemplary embodiments, the polishing surfaces of
the polishing elements may be made flush with or recessed below the
exposed major surface of the optional polishing composition
distribution layer. Such embodiments may be advantageously employed
to maintain a working liquid, for example a polishing slurry, at
the interface between the exposed polishing surfaces of the
polishing elements and a workpiece. In such embodiments, the
polishing composition distribution may be advantageously selected
to comprise a material that is abraded or eroded during the
polishing process or in optional conditioning processes applied to
the polishing surface of the polishing pad before, during, or after
contact with a workpiece.
[0094] In additional exemplary embodiments, the polishing
composition distribution layer may act to substantially uniformly
distribute a polishing composition across the surface of the
substrate undergoing polishing, which may provide more uniform
polishing. The polishing composition distribution layer may
optionally include flow resistant elements such as baffles, grooves
(not shown in the figures), pores, and the like, to regulate the
flow rate of the polishing composition during polishing. In further
exemplary embodiments, the polishing composition distribution layer
can include various layers of different materials to achieve
desired polishing composition flow rates at varying depths from the
polishing surface.
[0095] In some exemplary embodiments, one or more of the polishing
elements may include an open core region or cavity defined within
the polishing element, although such an arrangement is not
required. In some embodiments, as described in PCT International
Pub. No. WO 2006/055720, incorporated herein by reference, the core
of the polishing element can include sensors to detect pressure,
conductivity, capacitance, eddy currents, and the like. In yet
another embodiment, the polishing pad may include a window
extending through the pad in the direction normal to the polishing
surface, or may use transparent layers and/or transparent polishing
elements, to allow for optical end-pointing of a polishing process,
as described in PCT International Pub. No. WO 2009/140622, which is
incorporated herein by reference in its entirety.
[0096] The present disclosure is further directed to a method of
using a polishing pad as described above in a polishing process,
the method including contacting a surface of a substrate with a
polishing surface of a polishing pad comprising a plurality of
polishing elements, at least some of which are porous, and
relatively moving the polishing pad with respect to the substrate
to abrade the surface of the substrate. In certain exemplary
embodiments, a working liquid may be provided to an interface
between the polishing pad surface and the substrate surface.
Suitable working liquids are known in the art, and may be found,
for example, in U.S. Pat. Nos. 6,238,592 B1; 6,491,843 B1; and PCT
International Publication No. WO 2002/33736, the entire disclosures
of which are incorporated herein by reference.
[0097] The polishing pads described herein may, in some
embodiments, be relatively easy and inexpensive to manufacture. A
brief discussion of some exemplary methods for making polishing
pads according to the present disclosure is described below, which
discussion is not intended to be exhaustive or otherwise
limiting.
[0098] Thus, in another exemplary embodiment, the present
disclosure provides a method of making polishing pads as described
above, the method including mixing a first polymer with a second
polymer with application of heat to form a fluid molding
composition, dispensing the fluid molding composition into a mold,
cooling the fluid molding composition to form a polishing pad
including a first continuous polymer phase comprising the first
polymer, and a organic particulate filler comprising the second
polymer, wherein the polishing pad has a first major side or
surface and a second major side or surface opposite the first major
side or surface.
[0099] In an additional embodiment, the present disclosure provides
a method of making a polishing pad as described above, the method
including dispersing an organic particulate filler in a curable
composition comprising a polymeric precursor material, dispensing
the curable composition into a mold, curing the curable composition
in the mold to form a polymeric sheet containing the dispersed
organic particulate filler, the polymeric sheet having a first
major side and a second major side opposite the first major side,
and a plurality of polishing elements extending outwardly from the
first major side along a first direction substantially normal to
the first major side, wherein the polishing elements are integrally
formed with the sheet and laterally connected so as to restrict
lateral movement of the polishing elements with respect to one or
more of the other polishing elements, but remaining moveable in an
axis substantially normal to a polishing surface of the polishing
elements.
[0100] In some exemplary embodiments, dispersing the organic
particulate filler in the continuous polymer phase comprises melt
mixing, kneading, extrusion, or combinations thereof. In certain
exemplary embodiments, dispensing the fluid molding composition
into the mold comprises at least one of reaction injection molding,
extrusion molding, compression molding, vacuum molding, or a
combination thereof. In some particular exemplary embodiments,
dispensing comprises continuously extruding the fluid molding
composition through a film die onto a casting roller, further
wherein the surface of the casting roller comprises the mold.
[0101] In additional exemplary embodiments of making a textured
polishing pad as described above, the method further includes
milling at least one of the first and second major sides to form a
multiplicity of grooves extending into the side. In certain
exemplary embodiments, the grooves have a depth of from about 1
.mu.m to about 5,000 .mu.m. In some particular exemplary
embodiments, the polishing pad has a circular cross-section in a
direction substantially normal to the first and second sides,
wherein the circle defines a radial direction, and further wherein
the plurality of grooves are circular, concentric, and spaced apart
in the radial direction.
[0102] In an alternative exemplary embodiment of making a polishing
pad 2 wherein at least a portion of the plurality of polishing
elements comprise an organic particulate filler dispersed in a
continuous polymer phase as described above, the mold includes
comprises a three-dimensional pattern, and the first major surface
comprises a multiplicity of polishing elements corresponding to an
impression of the three-dimensional pattern, wherein the plurality
of polishing elements extend outwardly from the first major side
along a first direction substantially normal to the first major
side, further wherein the polishing elements are integrally formed
with the sheet and laterally connected so as to restrict lateral
movement of the polishing elements with respect to one or more of
the other polishing elements, but remaining moveable in an axis
substantially normal to a polishing surface of the polishing
elements.
[0103] The plurality of polishing elements may be formed from a
molten polymer continuous phase containing the dispersed organic
particulates using, for example, extrusion molding or compression
molding. To generate the polishing elements using extrusion
molding, a mixture of molten polymer containing the dispersed
organic particulates could be fed into a twin screw extruder
equipped with a film die and casting rolls possessing the desired
pre-determined pattern of polishing elements. Alternatively, a
polymeric film comprising the dispersed organic particulates could
be made and compression molded in a second operation with molding
plates possessing the desired pre-determined pattern of polishing
elements. Upon creation of the desired pattern of polishing
elements on the sheet, the sheet could be secured to a compliant
support layer, for example, by thermal bonding to a thermal bonding
film or by use of an adhesive. Alternatively the compliant support
layer could be laminated to the polishing surface during film
casting or compression molding.
[0104] In one particularly advantageous embodiment illustrating a
unitary polishing pad, a multi-cavity mold may be provided with a
back-fill chamber, wherein each cavity corresponds to a polishing
element. A plurality of polishing elements, which may include
porous polishing elements and nonporous polishing element as
described herein, may be formed by injection molding a suitable
polymer melt into the multi-cavity mold, and back-filling the
back-fill chamber with the same polymer melt or another polymer
melt to form a support layer. The polishing elements remain affixed
to the support layer upon cooling of the mold, thereby forming a
plurality of polishing elements as a unitary sheet of polishing
elements with the support layer. The mold may, in some embodiments,
comprise a rotating roll mold.
[0105] In another embodiment, the integrally molded sheet of
polishing elements could be scored between the individual raised
polishing elements to generate a polishing surface of individually
floating polishing elements. Alternatively, the segregation could
also be accomplished in the molding process by incorporating raised
areas in the mold between the individual raised elements.
[0106] Suitable molding materials, molds, apparatus and methods of
forming an integral sheet of polishing elements are described in
the Examples below and in PCT International Pub. No. WO
2009/158665.
[0107] In a further alternative embodiment, the present disclosure
provides a method of making a polishing pad 2' as described above,
the method including forming a multiplicity of polishing elements
including a first continuous polymer phase and an organic
particulate filler dispersed therein, and bonding the polishing
elements to a first major side of a support layer having a second
major side opposite the first major side to form a polishing pad.
In some exemplary embodiments, the method further includes affixing
a compliant layer to the second major side. In further exemplary
embodiments, the method further includes affixing a polishing
composition distribution layer covering at least a portion of the
first major side.
[0108] In some exemplary embodiments, the method additionally
includes forming a pattern with the polishing elements on the first
major side. In certain exemplary embodiments, forming a pattern
comprises reaction injection molding the polishing elements in the
pattern, extrusion molding the polishing elements in the pattern,
compression molding the polishing elements in the pattern,
arranging the polishing elements within a template corresponding to
the pattern, or arranging the polishing elements on the support
layer in the pattern. In some particular exemplary embodiments,
bonding the polishing elements to the support layer comprises
thermal bonding, ultrasonic bonding, actinic radiation bonding,
adhesive bonding, and combinations thereof.
[0109] In certain presently preferred embodiments, the polishing
elements are thermally bonded to the support layer. Thermal bonding
may be achieved, for example, by contacting a major surface of the
support layer with a surface of each polishing element to form a
bonding interface, and heating the polishing elements and the
support layer to a temperature at which the polishing elements and
support layer soften, melt, or flow together to form a bond at the
bonding interface. Ultrasonic welding may also be used to effect
thermal bonding of the polishing elements to the support layer. In
some presently preferred embodiments, pressure is applied to the
bonding interface while heating the polishing elements and the
support layer. In further presently preferred embodiments, the
support layer is heated to a temperature greater than the
temperature to which the polishing elements are heated.
[0110] In other exemplary embodiments, bonding the polishing
elements to the support layer involves using a bonding material
that forms a physical and/or chemical union at an interface between
the polishing elements and a major surface of the support layer.
Such a physical and/or chemical union may, in certain embodiments,
be formed using an adhesive positioned at the bonding interface
between each polishing element and the major surface of the support
layer. In other embodiments, the bonding material may be a material
that forms a bond by curing, for example, by thermally curing,
radiation curing (e.g. curing using actinic radiation such as
ultraviolet light, visible light, infrared light, electron beams or
other radiation sources), and the like.
[0111] Suitable bonding film materials, apparatus and methods are
described in PCT International Application No. PCT/US2009/051032,
filed Jul. 17, 2009, which is incorporated herein by reference in
its entirety.
[0112] In additional presently preferred exemplary embodiments, at
least a portion of the polishing elements comprise porous polishing
elements. In some exemplary embodiments, at least some of the
polishing elements comprise substantially non-porous polishing
elements. In some particular exemplary embodiments, the porous
polishing elements are formed by injection molding of a gas
saturated polymer melt, injection molding of a reactive mixture
that evolves a gas upon reaction to form a polymer, injection
molding of a mixture comprising a polymer dissolved in a
supercritical gas, injection molding of a mixture of incompatible
polymers in a solvent, injection molding of porous thermoset
particulates dispersed in a thermoplastic polymer, injection
molding of a mixture comprising microballoons, and combinations
thereof. In additional exemplary embodiments, the pores are formed
by reaction injection molding, gas dispersion foaming, and
combinations thereof.
[0113] In some exemplary embodiments, the porous polishing elements
have pores distributed substantially throughout the entire
polishing element. In other embodiments, the pores may be
distributed substantially at the polishing surface of the porous
polishing elements. In some additional embodiments, the porosity
imparted to the polishing surface of a porous polishing element may
be imparted, for example, by injection molding, calendaring,
mechanical drilling, laser drilling, needle punching, gas
dispersion foaming, chemical processing, and combinations
thereof.
[0114] It will be understood that the polishing pad need not
comprise only substantially identical polishing elements. Thus, for
example, any combination or arrangement of porous polishing
elements and non-porous polishing elements may make up the
plurality of porous polishing elements. It will also be understood
that any number, combination or arrangement of porous polishing
elements and substantially nonporous polishing elements may be used
advantageously in certain embodiments to form a polishing pad
having floating polishing elements bonded to a support layer.
[0115] In further exemplary embodiments, the polishing elements may
be arranged to form a pattern. Any pattern may be advantageously
employed. For example, the polishing elements may be arranged to
form a two-dimensional array, for example, a rectangular,
triangular, or circular array of polishing elements. In additional
exemplary embodiments, the polishing elements may include both
porous polishing elements and substantially nonporous polishing
elements arranged in a pattern on the support layer. In certain
exemplary embodiments, the porous polishing elements may be
advantageously arranged with respect to any substantially nonporous
polishing elements to form an arrangement of porous polishing
elements and nonporous polishing elements on the major surface of
the support layer. In such embodiments, the number and arrangement
of porous polishing elements relative to substantially nonporous
polishing elements may be selected advantageously to obtain
desirable polishing performance.
[0116] For example, in some exemplary embodiments, porous polishing
elements may be arranged substantially near the center of a major
surface of the polishing pad, and substantially nonporous polishing
elements may be arranged substantially near the peripheral edge of
the major surface of the polishing pad. Such exemplary embodiments
may desirably more effectively retain a working liquid, for example
an abrasive polishing slurry, in the contact zone between the
polishing pad and the wafer surface, thereby improving wafer
surface polishing uniformity (e.g. reduced dishing at the wafer
surface) as well as reducing the quantity of waste slurry generated
by the CMP process. Such exemplary embodiments may also desirably
provide more aggressive polishing at the edges of the die, thereby
reducing or eliminating the formation of an edge ridge, and
improving yield and die polish uniformity.
[0117] In other exemplary embodiments, porous polishing elements
may be arranged substantially near the edge of a major surface of
the polishing pad, and substantially nonporous polishing elements
may be arranged substantially near the center of the major surface
of the polishing pad. Other arrangements and/or patterns of
polishing elements are contemplated as falling within the scope of
the present disclosure.
[0118] In certain embodiments of making a polishing pad 2' as
described above, the polishing elements may be arranged in a
pattern by placement on a major surface of the support layer. In
other exemplary embodiments, the polishing elements may be arranged
in a pattern using a template of the desired pattern, and the
support layer may be positioned over or under the polishing
elements and the template prior to bonding, with a major surface of
the support layer contacting each polishing element at a bonding
interface.
[0119] Exemplary embodiments of polishing pads having polishing
elements according to the present disclosure may have various
features and characteristics that enable their use in a variety of
polishing applications. In some presently preferred embodiments,
polishing pads of the present disclosure may be particularly well
suited for chemical mechanical planarization (CMP) of wafers used
in manufacturing integrated circuits and semiconductor devices. In
certain exemplary embodiments, the polishing pad described in this
disclosure may provide advantages over polishing pads that are
known in the art.
[0120] For example, in some exemplary embodiments, a polishing pad
according to the present disclosure may act to better retain a
working liquid used in the CMP process at the interface between the
polishing surface of the pad and the substrate surface being
polished, thereby improving the effectiveness of the working liquid
in augmenting polishing. In other exemplary embodiments, a
polishing pad according to the present disclosure may reduce or
eliminate dishing and/or edge erosion of the wafer surface during
polishing. In some exemplary embodiments, use of a polishing pad
according to the present disclosure in a CMP process may result in
improved within wafer polishing uniformity, a flatter polished
wafer surface, an increase in edge die yield from the wafer, and
improved CMP process operating latitude and consistency.
[0121] In further exemplary embodiments, use of a polishing pad
with porous elements according to exemplary embodiments of the
present disclosure may permit processing of larger diameter wafers
while maintaining the required degree of surface uniformity to
obtain high chip yield, processing of more wafers before
conditioning of the pad surface is required in order to maintain
polishing uniformity of the wafer surface, or reducing process time
and wear on the pad conditioner.
[0122] Another advantage of using dispersed organic particulates in
a continuous polymer phase in forming textured polishing pads is
the apparent ease of machining or milling of the surface.
Commercially available CMP pads are typically composed of
cross-linked polyurethane foams which resist milling, and which are
extremely difficult to mill without tearing or damaging the foam. A
solid thermoplastic textured polishing pad material as described
herein deforms less during the milling operations, therefore making
it easier to mill and to generate a clean surface.
[0123] Exemplary polishing pads according to the present disclosure
will now be illustrated with reference to the following
non-limiting examples.
EXAMPLES
[0124] The following non-limiting examples illustrate various
methods for preparing both porous and non-porous polishing elements
which may be used to prepare polishing pads comprising a plurality
of polishing elements bonded to a support layer.
Example 1
[0125] Fabrication of a polishing pad 2 according to an exemplary
embodiment of the present disclosure was accomplished using the
following procedure. In a container, 14.9 g of a micronized
synthetic wax, MP-22.times.F (from Micro Powders, Inc., Tarrytown,
N.Y.) was mixed with 92.5 g of a TDI-polyether prepolymer,
Airthane.RTM. PHP-75D (from Air Products and Chemicals, Inc.,
Allentown, Pa.), forming a dispersion. In a 1 pint, metal
container, 12.0 g of oligomeric diamine,
polytetramethylene-oxide-di-p-aminobenzoate, VERSALINKP-650.RTM.
OLIGOMERIC DIAMINE (from Air Products and Chemicals, Inc.), and
50.0 g of 4,4'-methylene-bis(3-chloro-2,6-diethylaniline),
Versalink.RTM. MCDEA Curative (from Air Products and Chemicals,
Inc.), were combined. By placing the metal container on a hot
plate, the mixture was warmed to a temperature such that the
mixture became molten. The MP-22.times.F/Airthane.RTM. PHP-75D
dispersion was then added to the 1 pint container forming a resin
based slurry. The resulting resin based slurry was mixed at 1,000
rpm for 25 seconds and degassed at 1,500 rpms for 1 minute in an
Awatori-Rentaro AR-500 Thinky Mixer (from Thinky Corporation,
Tokyo, Japan).
[0126] Using a knife coater having a width of about 21 inch (53.3
cm), the slurry was coated between a 12 inch (30.5 cm) wide, 51
micron thick PET film liner and a 19 inch (48 cm) wide release
liner, 3M.TM. Secondary Liner 4935 (from 3M Company, St. Paul,
Minn.), and allowed to b-stage cure for 10 minutes at ambient
temperature. The side of the release liner having the release
characteristic was in contact with the slurry. The thickness of the
resin based slurry coating was about 1,016 .mu.m. The release liner
was rapidly removed, exposing the surface of the partially cured
resin.
[0127] A Teflon.RTM. coated metal screen about 12 inch.times.18
inch (30.5 cm.times.45.7 cm) and about 0.0625 inch (1.6 mm) in
thickness, having a hexagonal array of circular holes each about
6.2 mm in diameter and a center to center distance of about 8 mm,
was placed on top of the b-stage cured resin. The PET liner,
b-stage cured resin and metal screen were placed on a 12
inch.times.18 inch (30.5 cm.times.45.7 cm) by 0.125 inch (3.2 mm)
thick aluminum plate. A 12 inch.times.18 inch (30.5 cm.times.45.7
cm) by 0.0625 inch (1.6 mm) thick Teflon.RTM. sheet was placed on
top of the screen. The entire stack was then run through a two roll
laminator having rubber rolls loaded to 0.23 kg/cm (mass per lineal
inch of film width) and a speed of 0.6 msec.
[0128] The stack was placed in an air flow through oven set at
125.degree. C. The resin was cured in the oven for 2 hours. The
power to the oven was turned off and the resin was allowed to cool
overnight in the oven. After removing from the oven, the metal
screen was removed from the cured resin, forming a textured pad
surface adhered to the original PET liner. Using a 127 .mu.m thick
transfer adhesive, 3M Adhesive Transfer Tape 9672 (from 3M
Company), the PET liner of the structured pad surface was hand
laminated to a 12 inch.times.12 inch (30.5 cm.times.30.5 cm) by
0.0625 (1.59 mm) thick piece of polyurethane foam, Rogers Poron
urethane foam, part #4701-50-20062-04 (from American Flexible
Products, Inc., Chaska, Minn.). A 9 inch (23 cm) diameter pad was
die cut from the resulting laminate, forming an exemplary polishing
pad 2 of the present disclosure.
Example 2
[0129] Fabrication of another exemplary polishing pad 2 of the
present disclosure was ccomplished using the following procedure.
In a container, 67.25 g of a 45-75 .mu.m spherical polyethylene
beads (from Cospheric, LLC, Santa Barbara, Calif.) were mixed with
185.00 g of a TDI-polyether prepolymer, Airthane.RTM. PHP-75D (from
Air Products and Chemicals, Inc.), forming a homogeneous
dispersion. In a 1 pint, metal container, 24.0 g of oligomeric
diamine, polytetramethyleneoxide-di-p-aminobenzoate,
VERSALINKP-650.RTM. OLIGOMERIC DIAMINE (from Air Products and
Chemicals, Inc.), and 60.0 g of
4,4'-methylene-bis(3-chloro-2,6-diethylaniline), Versalink.RTM.
MCDEA Curative (from Air Products and Chemicals, Inc.), were
combined. By placing the metal container on a hot plate, the
mixture was warmed to a temperature such that the mixture became
molten. The polyethylene bead/Airthane.RTM. PHP-75D dispersion was
then added to the 1 pint container forming a resin-based slurry.
The resulting resin based slurry was mixed at 1,000 rpm for 1
minute and degassed at 2,000 rpms for 30 seconds in an
Awatori-Rentaro AR-500 Thinky Mixer (from Thinky Corporation).
[0130] Using a knife coater having a width of about 21 inch (53
cm), a 1,448 .mu.m thick, 21 inch (53 cm) cm wide coating of the
slurry was prepared on a 26 .mu.m thick support layer formed by
extrusion of a thermoplastic polyurethane (TPU), ESTANE 58887-NAT02
(available from Lubrizol Advanced Materials, Inc., Cleveland, Ohio)
into film form at 182.degree. C. onto a paper release liner. The
coated slurry and support layer were placed on a 24 inch.times.24
inch (61 cm.times.61 cm) by 0.25 inch (6.35 mm) thick aluminum
plate. Thirty-six magnets, 0.5 inch (1.25 cm) in diameter by 3/16
inch (0.48 cm) thick were fitted into recesses in the back of the
aluminum plate. The magnets were evenly distributed in a square
array.
[0131] A Teflon.RTM. coated metal screen, as described in Example
1, was placed on top of the resin and the entire stack was placed
in an air flow through oven set at 125.degree. C. The resin was
cured in the oven for 2 hours. After removing from the oven, the
metal screen was removed from the cured resin, forming a textured
pad surface adhered to the original paper backed polyurethane
support layer. The paper was removed exposing the opposite side of
the polyurethane support layer.
[0132] Using a 127 .mu.m thick transfer adhesive, 3M Adhesive
Transfer Tape 9672 (from 3M Company), the polyurethane support
layer of the textured pad surface was hand laminated to a 24
inch.times.24 inch (61 cm.times.61 cm) by 0.0625 inch (1.59 mm)
thick piece of polyurethane foam, Rogers Poron urethane foam, part
#4701-50-20062-04 (from American Flexible Products, Inc). A 20 inch
(51 cm) diameter pad was die cut from the laminate forming the pad
of the present disclosure.
[0133] The foregoing Examples 1-2 are directed to producing a
polishing pad including a sheet having a first major side and a
second major side opposite the first major side, and a plurality of
polishing elements extending outwardly from the first major side
along a first direction substantially normal to the first major
side, wherein at least a portion of the polishing elements are
integrally formed with the sheet and laterally connected so as to
restrict lateral movement of the polishing elements with respect to
one or more of the other polishing elements, but remaining moveable
in an axis substantially normal to a polishing surface of the
polishing elements, wherein at least a portion of the plurality of
polishing elements comprise an organic particulate filler in a
continuous polymer phase.
[0134] However, it will be understood that any of the foregoing
molded or roller embossed films of Examples 1-2 may be used to
create polishing elements 4 for use in producing a polishing pad 2'
including a support layer having a first major side and a second
major side opposite the first major side, and a multiplicity of
polishing elements bonded to the first major side of the support
layer, wherein each polishing element has an exposed polishing
surface, and wherein the polishing elements extend from the first
major side of the support layer along a first direction
substantially normal to the first major side, further wherein at
least a portion of the plurality of polishing elements comprise a
first continuous polymer phase and an organic particulate filler.
The molded or embossed elements polishing may, for example be cut
out of the film (e.g. using die cutting) and subsequently bonded to
the first major side of the support layer, preferably using direct
thermal bonding, as described above.
[0135] It will be further understood that the relative order and
arrangement of elements in the exemplary polishing pads and methods
may be varied without deviating from the scope of the disclosure.
Thus, for example, the support layer may be placed on a temporary
release layer and overlaid with a template bearing a desired
patterns for the polishing elements before arranging the polishing
elements in a two-dimensional array pattern in the template, and
thermally bonding the polishing elements to an overlaid support
layer (i.e. a thermal bonding film), for example, as described in
PCT International Application No. PCT/US2009/051032.
[0136] It will also be understood that the relative order and
arrangement of elements in the exemplary polishing pads and methods
described above may be varied without deviating from the scope of
the disclosure. It will be additionally understood that polishing
pads of exemplary embodiments the present disclosure need not
comprise only substantially identical polishing elements. Thus, for
example, any combination or arrangement of porous polishing
elements and non-porous polishing elements may make up the
plurality of porous polishing elements. It will also be understood
that any number, combination or arrangement of porous polishing
elements and substantially nonporous polishing elements may be used
advantageously in certain embodiments to form a polishing pad
having floating polishing elements bonded to a support layer.
Furthermore, porous polishing elements may be substituted for
nonporous polishing elements in any number, arrangement or
combination. Thus, using the teachings provided in the Detailed
Description and Examples hereinabove, individual porous and
optionally, nonporous polishing elements may be affixed to (or
integrally formed with) a support layer to provide polishing pads
of various additional embodiments of the present disclosure.
[0137] Lastly, it will be understood that polishing pads as
disclosed herein may generally include optional elements disclosed
herein in any combination, for example, an optional compliant layer
affixed to the second major side with an optional adhesive layer,
an optional pressure sensitive adhesive layer affixed to the
compliant layer opposite the second major side, an optional guide
plate (for polishing pad embodiments like 2'), an optional
polishing composition distribution layer, and the like.
[0138] Reference throughout this specification to "one embodiment",
"certain embodiments", "one or more embodiments" or "an
embodiment", whether or not including the term "exemplary"
preceding the term "embodiment", means that a particular feature,
structure, material, or characteristic described in connection with
the embodiment is included in at least one embodiment of the
certain exemplary embodiments of the present disclosure. Thus, the
appearances of the phrases such as "in one or more embodiments",
"in certain embodiments", "in one embodiment" or "in an embodiment"
in various places throughout this specification are not necessarily
referring to the same embodiment of the certain exemplary
embodiments of the present disclosure. Furthermore, the particular
features, structures, materials, or characteristics may be combined
in any suitable manner in one or more embodiments.
[0139] While the specification has described in detail certain
exemplary embodiments, it will be appreciated that those skilled in
the art, upon attaining an understanding of the foregoing, may
readily conceive of alterations to, variations of, and equivalents
to these embodiments. Accordingly, it should be understood that
this disclosure is not to be unduly limited to the illustrative
embodiments set forth hereinabove. In particular, as used herein,
the recitation of numerical ranges by endpoints is intended to
include all numbers subsumed within that range (e.g. 1 to 5
includes 1, 1.5, 2, 2.75, 3, 3.80, 4, and 5). In addition, all
numbers used herein are assumed to be modified by the term `about`.
Furthermore, all publications and patents referenced herein are
incorporated by reference in their entirety to the same extent as
if each individual publication or patent was specifically and
individually indicated to be incorporated by reference.
[0140] Various exemplary embodiments have been described. These and
other embodiments are within the scope of the following claims.
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