U.S. patent application number 13/034213 was filed with the patent office on 2011-11-10 for cmp pad dressers with hybridized conditioning and related methods.
Invention is credited to Chien-Min Sung.
Application Number | 20110275288 13/034213 |
Document ID | / |
Family ID | 44902244 |
Filed Date | 2011-11-10 |
United States Patent
Application |
20110275288 |
Kind Code |
A1 |
Sung; Chien-Min |
November 10, 2011 |
CMP PAD DRESSERS WITH HYBRIDIZED CONDITIONING AND RELATED
METHODS
Abstract
The present invention provides CMP pad dressers and methods for
dressing or conditioning CMP pads. In one aspect, for example, a
CMP pad conditioner is provided. Such a conditioner can include a
support matrix, and a plurality of smooth superabrasive particles
disposed in the support matrix, where the smooth superabrasive
particles are operable to cut large asperities in a CMP pad. The
conditioner also includes a plurality of rough superabrasive
particles disposed in the support matrix, where the rough
superabrasive particles operable to cut slurry channels on the
large asperities, and wherein the slurry channels are cut in such a
way as to facilitate slurry movement across the large asperities
during a CMP polishing process.
Inventors: |
Sung; Chien-Min;
(US) |
Family ID: |
44902244 |
Appl. No.: |
13/034213 |
Filed: |
February 24, 2011 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61333162 |
May 10, 2010 |
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Current U.S.
Class: |
451/56 ; 451/443;
451/527 |
Current CPC
Class: |
B24B 53/12 20130101;
B24B 53/017 20130101 |
Class at
Publication: |
451/56 ; 451/443;
451/527 |
International
Class: |
B24B 1/00 20060101
B24B001/00; B24D 11/00 20060101 B24D011/00; B24B 53/12 20060101
B24B053/12 |
Claims
1. A CMP pad conditioner, comprising: a support matrix; a plurality
of smooth superabrasive particles disposed in the support matrix,
the smooth superabrasive particles operable to cut large asperities
in a CMP pad; and a plurality of rough superabrasive particles
disposed in the support matrix, the rough superabrasive particles
operable to cut slurry channels on the large asperities, wherein
the slurry channels are operable to facilitate slurry movement
across the large asperities during a CMP polishing process.
2. The CMP pad conditioner of claim 1, wherein cutting tips of the
plurality of rough and the plurality of smooth superabrasive
particles are substantially leveled to an RA of from about 1 to
about 10 microns.
3. The CMP pad conditioner of claim 1, wherein the plurality of
smooth superabrasive particles are divided into one or more
discrete smooth superabrasive particle regions, and wherein the
plurality of rough superabrasive particles are divided into one or
more discrete rough superabrasive particle regions.
4. The CMP pad conditioner of claim 4, wherein the discrete smooth
superabrasive particle regions and the discrete rough superabrasive
particle regions are arranged in an alternating pattern.
5. The CMP pad conditioner of claim 1, wherein the plurality of
smooth superabrasive particles and the plurality of rough
superabrasive particles are interspersed across the support
matrix.
6. The CMP pad conditioner of claim 1, wherein the smooth
superabrasive particles are single crystal superabrasive
particles.
7. The CMP pad conditioner of claim 6, wherein the single crystal
superabrasive particles are single crystal diamond.
8. The CMP pad conditioner of claim 1, wherein the rough
superabrasive particles are polycrystalline superabrasive
particles.
9. The CMP pad conditioner of claim 8, wherein the polycrystalline
superabrasive particles are polycrystalline diamond.
10. The CMP pad conditioner of claim 1, wherein the rough
superabrasive particles are single crystal superabrasive particles
having broken tips, edges, faces, or a combination thereof.
11. The CMP pad conditioner of claim 1, wherein the smooth
superabrasive particles have a configuration sufficient to press at
least about 15 microns into a CMP pad before cutting occurs.
12. The CMP pad conditioner of claim 1, wherein the rough
superabrasive particles have a configuration sufficient to begin
cutting when pressed into a CMP pad less than or equal to about 10
microns.
13. The CMP pad conditioner of claim 1, wherein the support matrix
is a braze metal matrix.
14. The CMP pad conditioner of claim 1, wherein the support matrix
is an organic matrix.
15. The CMP pad conditioner of claim 14, wherein the organic matrix
includes a member selected from the group consisting of: amino
resins, acrylate resins, alkyd resins, polyester resins, polyamide
resins, polyimide resins, polyurethane resins, phenolic resins,
phenolic/latex resins, epoxy resins, isocyanate resins,
isocyanurate resins, polysiloxane resins, reactive vinyl resins,
polyethylene resins, polypropylene resins, polystyrene resins,
phenoxy resins, perylene resins, polysulfone resins,
acrylonitrile-butadiene-styrene resins, acrylic resins,
polycarbonate resins, polyimide resins, and combinations
thereof.
16. A method of conditioning a CMP pad, comprising: cutting large
asperities into a CMP pad surface using smooth superabrasive
particles; and cutting slurry channels on the large asperities of
the CMP pad surface using rough superabrasive particles, wherein
the slurry channels facilitate slurry movement across the large
asperities.
17. The method of claim 16, wherein the large asperities and the
slurry channels are cut simultaneously with the same CMP pad
dresser.
18. The method of claim 16, wherein the large asperities and the
slurry channels are cut sequentially with different CMP pad
dressers.
19. A CMP pad, comprising: a CMP pad material having a plurality of
large asperities cut therein; and a plurality of slurry channels
cut in the plurality of large asperities, the slurry channels being
operable to facilitate slurry movement across the large asperities
during a CMP polishing process.
20. The CMP pad of claim 19, wherein the CMP pad material is a
poreless CMP pad material.
Description
PRIORITY DATA
[0001] This application claims the benefit of U.S. Provisional
Patent Application Ser. No. 61/333,162, filed on May 10, 2010,
which is incorporated herein by reference.
FIELD OF THE INVENTION
[0002] The present invention relates generally to CMP pad
conditioners used to remove material from (e.g., smooth, polish,
dress, etc.) CMP pads. Accordingly, the present invention involves
the fields of chemistry, physics, and materials science.
BACKGROUND OF THE INVENTION
[0003] The semiconductor industry currently spends in excess of one
billion U.S. dollars each year manufacturing silicon wafers that
must exhibit very flat and smooth surfaces. Known techniques to
manufacture smooth and even-surfaced silicon wafers are plentiful.
The most common of these involves the process known as Chemical
Mechanical Polishing (CMP) which includes the use of a polishing
pad in combination with an abrasive slurry. Of central importance
in all CMP processes is the attainment of high performance levels
in aspects such as uniformity of polished wafer, smoothness of the
IC circuitry, removal rate for productivity, longevity of
consumables for CMP economics, etc.
SUMMARY OF THE INVENTION
[0004] The present invention provides CMP pad dressers and methods
for dressing or conditioning CMP pads. In one aspect, for example,
a CMP pad conditioner is provided. Such a conditioner can include a
support matrix, and a plurality of smooth superabrasive particles
disposed in the support matrix, where the smooth superabrasive
particles are operable to cut large asperities in a CMP pad. The
conditioner also includes a plurality of rough superabrasive
particles disposed in the support matrix, where the rough
superabrasive particles operable to cut slurry channels on the
large asperities, and wherein the slurry channels are cut in such a
way as to facilitate slurry movement across the large asperities
during a CMP polishing process.
[0005] Various configurations for superabrasive particles are
contemplated. In one aspect, for example, cutting tips of the
plurality of rough and the plurality of smooth superabrasive
particles are substantially leveled to an RA of from about 1 micron
to about 10 microns. In another aspect, the plurality of smooth
superabrasive particles are divided into one or more discrete
smooth superabrasive particle regions, and the plurality of rough
superabrasive particles are divided into one or more discrete rough
superabrasive particle regions. In a more specific aspect, the
discrete smooth superabrasive particle regions and the discrete
rough superabrasive particle regions are arranged in an alternating
pattern. Alternatively, in one aspect the plurality of smooth
superabrasive particles and the plurality of rough superabrasive
particles are interspersed across the support matrix.
[0006] Any superabrasive material and material configuration
capable of conditioning a CMP pad should be considered to be within
the present scope. In one aspect, for example, the smooth
superabrasive particles are single crystal superabrasive particles.
Single crystals can include, for example, diamond, cubic boron
nitride, ceramics, and the like. In one aspect, the single crystal
superabrasive particles are single crystal diamond. In another
aspect, the rough superabrasive particles are polycrystalline
superabrasive particles. Polycrystalline materials can include, for
example, diamond, cubic boron nitride, ceramics, and the like. In
one aspect, the polycrystalline superabrasive particles are
polycrystalline diamond. In yet another aspect, the rough
superabrasive particles can include single crystal superabrasive
particles having broken tips, edges, faces, or a combination
thereof.
[0007] A variety of support matrix materials are contemplated, and
any material capable of securing superabrasive particles in a tool
should be considered to be within the present scope. Support matrix
materials can include, without limitation, braze alloys, solid
metals including electroplated metals, organic materials, ceramics,
and the like. In one aspect, the support matrix is an organic
matrix. Examples of organic matrix materials can include, without
limitation, amino resins, acrylate resins, alkyd resins, polyester
resins, polyamide resins, polyimide resins, polyurethane resins,
phenolic resins, phenolic/latex resins, epoxy resins, isocyanate
resins, isocyanurate resins, polysiloxane resins, reactive vinyl
resins, polyethylene resins, polypropylene resins, polystyrene
resins, phenoxy resins, perylene resins, polysulfone resins,
acrylonitrile-butadiene-styrene resins, acrylic resins,
polycarbonate resins, polyimide resins, and the like, including
combinations thereof.
[0008] In another aspect of the present invention, a method of
conditioning a CMP pad is provided. Such a method can include
cutting large asperities into a CMP pad surface using smooth
superabrasive particles, and cutting slurry channels on the large
asperities of the CMP pad surface using rough superabrasive
particles, wherein the slurry channels facilitate slurry movement
across the large asperities. Various techniques are contemplated
for cutting the large asperities and slurry channels in the CMP
pad. In one aspect, for example, the large asperities and the
slurry channels are cut simultaneously with the same CMP pad
dresser. In another aspect, the large asperities and the slurry
channels are cut sequentially with different CMP pad dressers.
[0009] In another aspect of the present invention, a CMP pad is
provided. Such a pad can include a CMP pad material having a
plurality of large asperities cut therein, and a plurality of
slurry channels cut in the plurality of large asperities, where the
slurry channels are cut so as to facilitate slurry movement across
the large asperities during a CMP polishing process. In one
specific aspect, the CMP pad material is a poreless CMP pad
material.
[0010] There has thus been outlined, rather broadly, various
features of the invention so that the detailed description thereof
that follows may be better understood, and so that the present
contribution to the art may be better appreciated. Other features
of the present invention will become clearer from the following
detailed description of the invention, taken with any accompanying
or following claims, or may be learned by the practice of the
invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] FIG. 1 is a top plan view of an exemplary pad conditioner in
accordance with an embodiment of the invention.
[0012] It will be understood that the above figure is merely for
illustrative purposes in furthering an understanding of the
invention. Further, the figure may not be drawn to scale, thus
dimensions, particle sizes, and other aspects may, and generally
are, exaggerated to make illustrations thereof clearer. Therefore,
it will be appreciated that departure can and likely will be made
from the specific dimensions and aspects shown in the figure in
order to produce the pad conditioners of the present invention.
DETAILED DESCRIPTION
[0013] Before the present invention is disclosed and described, it
is to be understood that this invention is not limited to the
particular structures, process steps, or materials disclosed
herein, but is extended to equivalents thereof as would be
recognized by those ordinarily skilled in the relevant arts. It
should also be understood that terminology employed herein is used
for the purpose of describing particular embodiments only and is
not intended to be limiting.
[0014] It should be noted that, as used in this specification and
any appended or following claims, the singular forms "a," "an" and
"the" include plural referents unless the context clearly dictates
otherwise. Thus, for example, reference to "a particle" can include
one or more of such particles.
Definitions
[0015] In describing and claiming the present invention, the
following terminology will be used in accordance with the
definitions set forth below.
[0016] As used herein, the terms "pad conditioner" and "pad
dresser" can be used interchangeably, and refer to a tool used to
condition or dress a pad, such as a CMP pad.
[0017] As used herein, a pad conditioner "substrate" or "support
substrate" refers to a portion of a pad conditioner that supports
an organic matrix, and to which abrasive materials, segment blanks
that carry abrasive materials, cutting elements, control elements,
etc. may be affixed. Substrates useful in the present invention may
be of a variety of shapes, thicknesses, or materials that are
capable of supporting an organic matrix in a manner that is
sufficient to provide a pad conditioner useful for its intended
purpose. Substrates may be of a solid material, a powdered material
that becomes solid when processed, or a flexible material. Examples
of typical substrate materials include without limitation, metals,
metal alloys, ceramics, relatively hard polymers or other organic
materials, glasses, and mixtures or combinations thereof.
[0018] As used herein, an "abrading surface or point" may be used
to refer to a surface, edge, face, point or peak of an abrasive
segment or cutting element that contacts and removes material from
a CMP pad. Generally speaking, the abrading surface or point is the
portion of the abrasive segment that first contacts the CMP pad as
the abrasive segment or cutting element and the CMP pad are brought
into contact with one another.
[0019] As used herein, "segment blank" refers to a structure
similar in many respects to the pad conditioner substrates defined
above. Segment blanks are utilized in the present invention to
carry abrasive layers: attachment of the abrasive layers to the pad
conditioner substrates is typically achieved by way of attaching
the segment blanks to the pad conditioner substrates. It is
important to note that a variety of techniques of attaching the
segment blanks to the substrates, and a variety of techniques of
attaching the abrasive layers to the segment blanks, are discussed
herein. It is to be understood that all of these various attachment
mechanisms can be used interchangeably herein: that is, if a method
of attaching a segment blank to a substrate is discussed herein,
the method of attachment discussed can also be used to attach an
abrasive layer to a segment blank. For any particular CMP pad
dresser being discussed, however, it is understood that attachment
methods of the abrasive layers to the segment blanks can differ
from, or can be the same as, the method used to attach the segment
blanks to the pad conditioner substrate.
[0020] As used herein, "superhard" may be used to refer to any
crystalline, or polycrystalline material, or mixture of such
materials which has a Mohr's hardness of about 8 or greater. In
some aspects, the Mohr's hardness may be about 9.5 or greater. Such
materials include but are not limited to diamond, polycrystalline
diamond (PCD), cubic boron nitride (cBN), polycrystalline cubic
boron nitride (PcBN), corundum and sapphire, as well as other
superhard materials known to those skilled in the art. Superhard
materials may be incorporated into the present invention in a
variety of forms including particles, grits, films, layers, pieces,
segments, etc. In some cases, the superhard materials of the
present invention are in the form of polycrystalline superhard
materials, such as PCD and PcBN materials.
[0021] As used herein, "organic material" refers to a semisolid or
solid complex or mix of organic compounds. "Organic material layer"
and "organic matrix" may be used interchangeably, and refer to a
layer or mass of a semisolid or solid complex or mix of organic
compounds, including resins, polymers, gums, etc. The organic
material can be a polymer or copolymer formed from the
polymerization of one or more monomers. In some cases, such organic
material can be adhesive.
[0022] As used herein, the process of "brazing" is intended to
refer to the creation of chemical bonds between the carbon atoms of
the superabrasive particles/materials and the braze material.
Further, "chemical bond" means a covalent bond, such as a carbide
or boride bond, rather than mechanical or weaker inter-atom
attractive forces. Thus, when "brazing" is used in connection with
superabrasive particles a true chemical bond is being formed.
However, when "brazing" is used in connection with metal to metal
bonding the term is used in the more traditional sense of a
metallurgical bond. Therefore, brazing of a superabrasive segment
to a tool body does not necessarily require the presence of a
carbide former.
[0023] As used herein, an "abrasive layer" describes a variety of
structures capable of removing (e.g., cutting, polishing, scraping)
material from a CMP pad. An abrasive layer can include a mass
having several cutting points, ridges or mesas formed thereon or
therein. It is notable that such cutting points, ridges or mesas
may be from a multiplicity of protrusions or asperities included in
the mass. Furthermore, an abrasive layer can include a plurality of
individual abrasive particles that may have only one cutting point,
ridge or mesa formed thereon or therein. An abrasive layer can also
include composite masses, such as PCD pieces, segment or blanks,
either individually comprising the abrasive layer or collectively
comprising the abrasive layer.
[0024] As used herein, "metallic" includes any type of metal, metal
alloy, or mixture thereof, and specifically includes but is not
limited to steel, iron, and stainless steel.
[0025] As used herein, "material characteristic" refers to the
physical and/or chemical properties of a CMP pad. These can include
properties such as molecular makeup, compressibility, softness,
pore density, and the like.
[0026] As used herein, "cutting element" refers to an element of a
CMP pad dresser that is intended to cut, abrade, remover, or
otherwise reorganize the material of a CMP pad for the purpose of
conditioning or dressing. Cutting elements can function using a
point, edge, face, or any other region of the cutting element that
is capable of conditioning or dressing the CMP pad. Cutting
elements should be considered to include individual cutters such as
diamond particles, as well as segment blanks that contain multiple
cutters provided the context allows.
[0027] As used herein, the term "substantially" refers to the
complete or nearly complete extent or degree of an action,
characteristic, property, state, structure, item, or result. As an
arbitrary example, when two or more objects are referred to as
being spaced a "substantially" constant distance from one another,
it is understood that the two or more objects are spaced a
completely unchanging distance from one another, or so nearly an
unchanging distance from one another that a typical person would be
unable to appreciate the difference. The exact allowable degree of
deviation from absolute completeness may in some cases depend upon
the specific context. However, generally speaking the nearness of
completion will be so as to have the same overall result as if
absolute and total completion were obtained.
[0028] The use of "substantially" is equally applicable when used
in a negative connotation to refer to the complete or near complete
lack of an action, characteristic, property, state, structure,
item, or result. As an arbitrary example, a cavity that is
"substantially free of" foreign matter would either completely lack
any foreign matter, or so nearly completely lack foreign matter
that the effect would be the same as if it completely lacked
foreign matter. In other words, a cavity that is "substantially
free of" foreign matter may still actually contain minute portions
of foreign matter so long as there is no measurable effect upon the
cavity as a result thereof.
[0029] As used herein, a plurality of items, structural elements,
compositional elements, and/or materials may be presented in a
common list for convenience. However, these lists should be
construed as though each member of the list is individually
identified as a separate and unique member. Thus, no individual
member of such list should be construed as a de facto equivalent of
any other member of the same list solely based on their
presentation in a common group without indications to the
contrary.
[0030] Concentrations, amounts, particle sizes, volumes, and other
numerical data may be expressed or presented herein in a range
format. It is to be understood that such a range format is used
merely for convenience and brevity and thus should be interpreted
flexibly to include not only the numerical values explicitly
recited as the limits of the range, but also to include all the
individual numerical values or sub-ranges encompassed within that
range as if each numerical value and sub-range is explicitly
recited.
[0031] As an illustration, a numerical range of "about 1 micrometer
to about 5 micrometers" should be interpreted to include not only
the explicitly recited values of about 1 micrometer to about 5
micrometers, but also include individual values and sub-ranges
within the indicated range. Thus, included in this numerical range
are individual values such as 2, 3, and 4 and sub-ranges such as
from 1-3, from 2-4, and from 3-5, etc. This same principle applies
to ranges reciting only one numerical value. Furthermore, such an
interpretation should apply regardless of the breadth of the range
or the characteristics being described.
The Invention
[0032] The present invention generally provides pad conditioners
and associated methods that can be utilized in conditioning (e.g.,
smoothing, polishing, dressing) or otherwise affecting a CMP pad to
remove material from the CMP pad in order to provide a finished,
smooth and/or flat surface to the pad. Pad conditioners of the
present invention can be advantageously utilized, for example, in
dressing CMP pads that are used in polishing, finishing or
otherwise affecting silicon wafers.
[0033] It has now been discovered that CMP processing can be
improved by conditioning the CMP pad in such a way as to facilitate
slurry movement across pad asperities. This can be accomplished by
conditioning the CMP pad with superabrasive particles having smooth
surfaces and with superabrasive particles having rough surfaces.
Because smooth superabrasive particles generally do not have sharp
cutting regions, they tend to cause significant elastic and plastic
deformation of the pad prior to pad penetration. As a result,
smooth superabrasive particles function to roughen the CMP pad by
creating large asperities in the pad surface.
[0034] Rough superabrasive particles, on the other hand, have sharp
cutting regions (e.g. tips, edges, and/or faces) that can readily
cut the CMP pad with less deformation as compared to smooth
superabrasive particles. These sharp cutting regions can include,
without limitation, broken single crystal particles or
polycrystalline particles having a multitude of cutting crystals.
These rough superabrasive particles function to remove the glaze
from the pad surface during the conditioning process. Additionally,
rough superabrasive particles cut small slurry channels into the
pad surface along the asperities. During a CMP operation, slurry
tends to accumulate in the valleys between asperities rather than
at the asperity tips, due in part to the contact pressure exerted
between the asperity tips and the workpiece. Much of the CMP
polishing occurs at the tips of the asperities, and as such, slurry
is often not in optimal contact with the workpiece being polished.
This situation can be particularly problematic for polishing
procedures utilizing the slurry to cause oxidative reactions on
materials such as copper. Because less slurry contacts the
workpiece, less oxidative reaction occurs. Slurry channels in the
asperities thus facilitate slurry movement out of the valleys
between the asperities and across the asperities themselves. As
such, a greater proportion of the slurry can be present on the
asperities during a CMP operation.
[0035] Various techniques can be utilized to condition a CMP pad
with both smooth and rough superabrasive particles. For example, in
one aspect the CMP pad can be sequentially conditioned using a
conditioner having one type of superabrasive particle, and then
conditioned using a conditioner having the other type of
superabrasive particle. For example, the CMP pad could be
conditioned using a conditioner having smooth superabrasive
particles, and then conditioned using a conditioner having rough
superabrasive particles. In another aspect, a CMP pad conditioner
can have both smooth and rough superabrasive particles to condition
the CMP pad concomitantly.
[0036] The smooth and rough superabrasive particles can be
incorporated into a CMP pad conditioner in a variety of ways. A CMP
pad conditioner will generally have a support substrate to which
the superabrasive particles are coupled using a support matrix. In
some cases, the support substrate can be constructed from the
support matrix. In some aspects, the superabrasive particles can be
disposed directly into the support matrix. In other aspects the
superabrasive particles can be coupled to a segment blank that is
then disposed into the support matrix. This latter aspect allows
smaller segments of superabrasive particles to be constructed and
then incorporated into the CMP pad conditioner.
[0037] One factor that can impact the methods of constructing a CMP
pad conditioner is the relative leveling of the superabrasive
particles across the surface of the conditioner. A variety of
contours or profiles are possible across the tips of the
superabrasive particles in a conditioner. For example, the profile
can be a flat profile, where the superabrasive particle tips are
leveled along a plane. The tips can be arranged along a slope or a
curvature as well. Such an arrangement is still considered to be
"leveled" because the tips lie along a predetermined profile.
Particle tips that sit significantly lower or higher than this
profile would thus not be leveled. Those that sit too low do not
contact the pad with sufficient pressure to condition, while those
that sit too high cut very large asperities that can cause damage
to the workpiece. Additionally, particles that sit too high above
the profile experience greater drag from the CMP pad, and can be
pulled loose from the conditioner. When this happens, the dislodged
particle can cause damage to the workpiece.
[0038] In addition to the effectiveness of cutting and the lower
risk of workpiece damage, leveled particle tips allows optimal
cutting of slurry channels in the asperities of the pad. For
example, rough superabrasive particles that sit below the profile
may not cut channels to the tips of the asperities, potentially
limiting the movement of slurry to the contact point between the
workpiece and the asperities. Rough particles that sit above the
profile may cut the asperities so aggressively that the benefits
provided by the smooth superabrasive particles are limited.
[0039] Making a conditioner having leveled tips can be problematic,
however, particularly using conventional superabrasive tool
techniques. For example, traditional braze alloy support matrix
tools embed superabrasive particles in a green braze alloy
precursor. The braze alloy is melted and then allowed to cool in
order to affix the superabrasive particles. Even assuming the tips
of the superabrasive particle were leveled prior to melting the
braze alloy, the cooling process causes the support substrate to
warp, thus pulling the tips out of the leveled alignment.
[0040] Various techniques are contemplated for the leveling of
superabrasive tips in a CMP pad conditioner, and any technique that
is capable of producing leveled tips in a finished conditioner
should be considered to be within the present scope. In one aspect,
for example, the support matrix can be an organic material. Organic
materials can be cured at temperatures that do not cause warpage of
the support substrate, and as such, particle tips that are leveled
prior to curing will remain leveled after curing. Organic matrix
materials can be problematic, however, because superabrasive
particles are much more weakly bonded to an organic matrix as
compared to a braze alloy. As a solution to this weak bonding
problem, the inventor has discovered that superabrasive particles
can be sufficiently retained in an organic matrix by arranging the
particles such that mechanical stress or friction is evenly
distributed across all superabrasive particles in the matrix.
[0041] As such, the smooth and rough superabrasive particles can be
directly disposed in an organic matrix, or they can be coupled to a
segment blank and the segment blank can be disposed in the organic
matrix. Superabrasive particles can be coupled to the segment blank
using an organic material, a braze alloy, a ceramic material,
electroplating, and the like. Segment blanks can be useful because
superabrasive particles can be more easily leveled across a small
area as compared to an entire CMP pad conditioner surface. In the
case of braze alloys for example, warpage of a segment blank is
much less during cooling because the surface area of the segment
blank is much smaller that the support substrate. As such, the
leveled configuration can be maintained during brazing of the
segment blank. The segment blanks can then be coupled to the
surface of the support substrate. If a braze alloy is used to
secure the segment blank to the support substrate, the warpage of
the support substrate is reduced by the added stiffness of the
segment blanks. As such, the segment blanks can be secured to the
support substrate using an organic material, a braze alloy, a
ceramic material, electroplating, and the like.
[0042] Other advantages for using segment blanks include the
ability to customize methods of attachment of the abrasive layer to
the segment blank independently of methods of attachment of the
segment blank or blanks to the pad conditioner substrate. For
example, as various attachment methods may involve very high
temperatures and/or pressures, very demanding environmental
conditions, or simply are very labor intensive when attempted with
pad conditioners of large or complex surface areas, performing the
attachment method on distinct, easily handled segment blanks can
improve costs, efficiencies and integrities of the attachment
process. Also, leveling of the superabrasive particles on each
segment blank can be performed more easily when done in discrete,
relatively small lots. The resulting plurality of abrasive segments
can likewise be more easily positioned, leveled, spaced, oriented,
etc., across the face of the pad conditioner substrate after the
abrasive layer is individually attached to each of the abrasive
segments.
[0043] In addition, by obtaining a plurality of abrasive segments,
each with a different configuration of superabrasive particles
already attached thereto, an abrasive pattern across the face of
the pad conditioner substrate can be designed to optimize various
conditioning procedures. For example, the spacing between adjacent
abrasive segments can be carefully selected to aid in, or better
control, the flow of various fluids (e.g., slurry) around and
through the abrasive segments to increase the efficacy and
efficiency of the material removing process. Also, as shown in FIG.
1, segment blanks having differing abrasive profiles (e.g.,
different sizes, shapes, abrasive aggressiveness, etc.) can be used
on a single substrate, to enable customization of an abrading
profile of the pad conditioner as a whole.
[0044] The rough and smooth superabrasive particles can be leveled
to various degrees depending on the nature of the CMP pad and the
workpiece being processed. While the cutting tips of the
superabrasive particles lie along a specific profile that may or
may not be planar, leveling refers to the deviation from that
profile. In one aspect, for example, the cutting tips of the
plurality of rough and the plurality of smooth superabrasive
particles are substantially leveled to and RA of from about 1 to
about 10 microns. In another aspect, the cutting tips of the
plurality of rough and the plurality of smooth superabrasive
particles are substantially leveled to and RA of from about 2 to
about 3 microns.
[0045] Whether the superabrasive particle are disposed directly in
the support matrix or are coupled to segment blanks, various
arrangements are contemplated. Arrangement schemes can vary
depending on the desired conditioning of the pad, and as such, the
following arrangements should not be seen as limiting. For example,
in one aspect smooth superabrasive particles are divided into one
or more discrete smooth superabrasive particle regions, and the
rough superabrasive particles are divided into one or more discrete
rough superabrasive particle regions. These regions can be regions
of particular types of superabrasive particles disposed directly in
the support matrix at specific locations, or segment blanks can be
constructed having a single type of superabrasive particle embedded
thereon. In one specific aspect, as is shown in FIG. 1, the
discrete smooth superabrasive particle regions 12 and the discrete
rough superabrasive particle regions 14 are arranged on the support
substrate 16 in an alternating pattern. In another aspect, the
plurality of smooth superabrasive particles and the plurality of
rough superabrasive particles are interspersed across the support
matrix (not shown). This can be accomplished through both types of
superabrasive particles interspersed directly into the support
matrix, or by interspersing a mixture of both types of
superabrasive particles on a segment blank.
[0046] The CMP pad conditioner can also include multiple annular
rings of superabrasive particle regions, as opposed to the single
annular ring shown in FIG. 1. Furthermore, it should be noted that
regions or segments would also include arrangements where grouped
multiples of one or more regions or segments were included in the
pattern.
[0047] While these techniques can be used to dress a variety of CMP
pad materials, they can be particularly beneficial for dressing
poreless CMP pad materials. Poreless CMP pads do not hold and move
slurry effectively because they lack pores to contain and hold the
slurry. As such, the problems associated with the slurry being
contained in the valleys between asperities is exacerbated by such
materials.
[0048] By cutting slurry channels through the pad surface, slurry
movement to the work piece up the asperities is facilitated, thus
increasing the effectiveness of poreless materials. Thus smooth
superabrasive particles can roughen such a pad, and rough
superabrasive particles can cut slurry channels that allow slurry
to wick across the pad surface.
[0049] The methods according to aspects of the present invention
can also be used to dress impregnated pads, such as
graphite-impregnated pads. Additional information regarding such
pads can be found in U.S. Pat. No. 7,494,404, filed on Jul. 6,
2007, and in U.S. patent application Ser. No. 12/389,922, filed on
Feb. 20, 2009, both of which are incorporated herein by
reference.
[0050] A variety of materials are contemplated for use as rough and
smooth superabrasive particles. Any superabrasive known that can be
utilized in a CMP pad dresser should be considered to be within the
present scope. Non-limiting examples of such materials include
diamond materials, nitride materials, ceramics, and the like. In
one aspect, the superabrasive particles include diamond materials.
Such diamond materials can include natural or synthetic diamond,
single crystal, polycrystalline, and the like. In another aspect,
the superabrasive particles include cubic boron nitride
materials.
[0051] In one aspect, the smooth superabrasive particles are single
crystal superabrasive particles. In one specific aspect, the single
crystal superabrasive particles can be diamond. Euhedral diamond
crystals have obtuse tips due to the crystallographic angles formed
by the (100), (111), (110) and other faces. Such diamond materials
can be used as smooth superabrasive particles to form large
asperities in the CMP pad. Smooth superabrasive particles can also
be referred to as deforming superabrasive particles.
[0052] In another aspect, rough superabrasive particles can be
single crystal superabrasive particles having broken tips, edges,
faces, or a combination thereof. The broken portions tend to be
sharp, allowing the cutting of the slurry channels into the pad
material. In yet another aspect, the rough superabrasive particles
are polycrystalline superabrasive particles. Polycrystalline
materials have a multitude of smaller crystals at the particle
surface that can effectively cut slurry channels into the pad, as
well as facilitating the removal of glaze and other debris. In one
specific aspect, the polycrystalline superabrasive particles are
polycrystalline diamond. Rough superabrasive particles can also be
referred to as cutting superabrasive particles.
[0053] In one aspect, the smooth superabrasive particles can be
distinguished by how far into the CMP pad a particle can be pressed
before cutting occurs. In one aspect, for example, a smooth
superabrasive particle is pressed into a CMP pad at least 15
microns before cutting occurs. In another aspect, a smooth
superabrasive particle is pressed into a CMP pad at least 20
microns before cutting occurs. Similarly, rough superabrasive
particles can be distinguished by how far into the CMP pad a
particle can be pressed before cutting occurs. In one aspect, for
example, a rough superabrasive particle begins cutting when pressed
into a CMP pad less than or equal to about 10 microns. In another
aspect, a rough superabrasive particle begins cutting when pressed
into a CMP pad less than or equal to about 5 microns.
[0054] The pad conditioner substrate can vary according to the
applications for which the pad conditioner is designed, but in one
aspect includes a face on which the support matrix can be affixed
to allow the pad conditioner to be used to grind, plane, cut or
otherwise remove material from a CMP pad. In one aspect, the
conditioner or support substrate can be stainless steel. In another
aspect, the support substrate can be regular steel. If regular
steel is used, it may be beneficial to electroplate the working
surface following fixing the superabrasive particles to provide
acid resistance to the conditioner.
[0055] Additional and varying abrasive segments for use in the
present invention are also contemplated. For example, use is
contemplated of the various cutting elements/abrasive segments
detailed in U.S. patent application Ser. No. 11/357,713, filed Feb.
17, 2006, which is hereby incorporated herein by reference. In
addition, the abrasive segments can be formed utilizing ceramic
components (as either or both the segment blank and/or the abrasive
layer), electroplating techniques, etc.
[0056] The various segment blanks shown and discussed herein can be
formed from a variety of materials, including, without limitation,
metallic materials such as aluminum, copper, steel, metal alloys,
etc., ceramic materials, glasses, polymers, composite materials,
etc. Generally speaking, virtually any material to which a
superabrasive particle can be attached thereto will suffice.
[0057] Various organic materials are contemplated for use as a
support matrix and/or to be used to secure superabrasive particles
to a segment blank. Examples of suitable organic matrix materials
include, without limitation, amino resins, acrylate resins, alkyd
resins, polyester resins, polyamide resins, polyimide resins,
polyurethane resins, phenolic resins, phenolic/latex resins, epoxy
resins, isocyanate resins, isocyanurate resins, polysiloxane
resins, reactive vinyl resins, polyethylene resins, polypropylene
resins, polystyrene resins, phenoxy resins, perylene resins,
polysulfone resins, acrylonitrile-butadiene-styrene resins, acrylic
resins, polycarbonate resins, polyimide resins, and mixtures
thereof. In one specific aspect, the organic matrix material can be
an epoxy resin. In another aspect, the organic matrix material can
be a polyimide resin. In yet another aspect, the organic matrix
material can be a polyurethane resin.
[0058] So-called "reverse casting" methods can be used to
accurately and controllably orient and attach superabrasive
particles onto a segment blank, as well as to orient and attach the
segment blanks to the pad conditioner support substrate. Such
methods can include initially securing a superabrasive material,
e.g., a plurality of superabrasive particles or a segment blank, to
a substrate using a "mask" material. The portions of the particles
protruding from the mask material can then be attached to a
substrate, such as a segment blank, using the methods discussed
herein, after which (or during which), the masking material can be
removed.
[0059] Suitable reverse casting methods can be found in various
patents and patent applications to the present inventor, including
U.S. Patent Application Ser. No. 60/992,966, filed Dec. 6, 2007;
U.S. patent application Ser. No. 11/804,221, filed May 16, 2007;
and U.S. patent application Ser. No. 11/805,549, filed May 22,
2007, each of which is hereby incorporated herein by reference.
These techniques can also be used when attaching the abrasive
segments of the present invention to pad conditioner support
substrate in addition to attaching the superabrasive particles to
the segment blanks. Such techniques allow very precise control of
lateral placement of the abrasive segments or superabrasive
particles, as well as very precise control of relative elevation of
the abrasive segments or superabrasive particles.
[0060] When an organic bonding material layer is utilized, methods
of curing the organic material layer can be a variety of processes
known to one skilled in the art that cause a phase transition in
the organic material from at least a pliable state to at least a
rigid state. Curing can occur, without limitation, by exposing the
organic material to energy in the form of heat, electromagnetic
radiation, such as ultraviolet, infrared, and microwave radiation,
particle bombardment, such as an electron beam, organic catalysts,
inorganic catalysts, or any other curing method known to one
skilled in the art.
[0061] In one aspect of the present invention, the organic material
layer may be a thermoplastic material. Thermoplastic materials can
be reversibly hardened and softened by cooling and heating
respectively. In another aspect, the organic material layer may be
a thermosetting material. Thermosetting materials cannot be
reversibly hardened and softened as with the thermoplastic
materials. In other words, once curing has occurred, the process
can be essentially irreversible, if desired.
[0062] As a more detailed list of what is described above, organic
materials that may be useful in embodiments of the present
invention include, but are not limited to: amino resins including
alkylated urea-formaldehyde resins, melamine-formaldehyde resins,
and alkylated benzoguanamine-formaldehyde resins; acrylate resins
including vinyl acrylates, acrylated epoxies, acrylated urethanes,
acrylated polyesters, acrylated acrylics, acrylated polyethers,
vinyl ethers, acrylated oils, acrylated silicons, and associated
methacrylates; alkyd resins such as urethane alkyd resins;
polyester resins; polyamide resins; polyimide resins; reactive
urethane resins; polyurethane resins; phenolic resins such as
resole and novolac resins; phenolic/latex resins; epoxy resins such
as bisphenol epoxy resins; isocyanate resins; isocyanurate resins;
polysiloxane resins including alkylalkoxysilane resins; reactive
vinyl resins; resins marketed under the Bakelite.TM. trade name,
including polyethylene resins, polypropylene resins, epoxy resins,
phenolic resins, polystyrene resins, phenoxy resins, perylene
resins, polysulfone resins, ethylene copolymer resins,
acrylonitrile-butadiene-styrene (ABS) resins, acrylic resins, and
vinyl resins; acrylic resins; polycarbonate resins; and mixtures
and combinations thereof. In one aspect of the present invention,
the organic material may be an epoxy resin. In another aspect, the
organic material may be a polyimide resin. In yet another aspect,
the organic material may be a polyurethane resin.
[0063] Numerous additives may be included in the organic material
to facilitate its use. For example, additional crosslinking agents
and fillers may be used to improve the cured characteristics of the
organic material layer. Additionally, solvents may be utilized to
alter the characteristics of the organic material in the uncured
state. Also, a reinforcing material may be disposed within at least
a portion of the solidified organic material layer. Such
reinforcing material may function to increase the strength of the
organic material layer, and thus further improve the retention of
the individual abrasive segments. In one aspect, the reinforcing
material may include ceramics, metals, or combinations thereof.
Examples of ceramics include alumina, aluminum carbide, silica,
silicon carbide, zirconia, zirconium carbide, and mixtures
thereof.
[0064] Additionally, in one aspect a coupling agent or an
organometallic compound may be coated onto the surface of each
superabrasive material to facilitate the retention of the
superabrasive particles in the organic material via chemical
bonding. A wide variety of organic and organometallic compounds is
known to those of ordinary skill in the art and may be used.
Organometallic coupling agents can form chemicals bonds between the
superabrasive materials and the organic material matrix, thus
increasing the retention of the superabrasive materials therein. In
this way, the organometallic coupling agent can serve as a bridge
to form bonds between the organic material matrix and the surface
of the superabrasive material. In one aspect of the present
invention, the organometallic coupling agent can be a titanate,
zirconate, silane, or mixture thereof. The amount of organometallic
coupling agent used can depend upon the coupling agent and on the
surface area of the superabrasive material. Oftentimes, 0.05% to
10% by weight of the organic material layer can be sufficient.
[0065] Specific non-limiting examples of silanes suitable for use
in the present invention include: 3-glycidoxypropyltrimethoxy
silane (available from Dow Corning as Z-6040); .gamma.-methacryloxy
propyltrimethoxy silane (available from Union Carbide Chemicals
Company as A-174); .beta.-(3,4-epoxycyclohexyl)ethyltrimethoxy
silane, .gamma.-aminopropyltriethoxy silane,
N-(.beta.-aminoethyl)-.gamma.-aminopropylmethyldimethoxy silane
(available from Union Carbide, Shin-etsu Kagaku Kogyo K.K., etc.).
Specific non-limiting examples of titanate coupling agents include:
isopropyltriisostearoyl titanate, di(cumylphenylate)oxyacetate
titanate, 4-aminobenzenesulfonyldodecylbenzenesulfonyl titanate,
tetraoctylbis (ditridecylphosphite) titanate,
isopropyltri(N-ethylamino-ethylamino) titanate (available from
Kenrich Petrochemicals. Inc.), neoalkyoxy titanates such as
LICA-01, LICA-09, LICA-28, LICA-44 and LICA-97 (also available from
Kenrich), and the like. Specific non-limiting examples of aluminum
coupling agents include acetoalkoxy aluminum diisopropylate
(available from Ajinomoto K.K.), and the like. Specific
non-limiting examples of zirconate coupling agents include:
neoalkoxy zirconates, LZ-01, LZ-09, LZ-12, LZ-38, LZ-44, LZ-97 (all
available from Kenrich Petrochemicals, Inc.), and the like. Other
known organometallic coupling agents, e.g., thiolate based
compounds, can be used in the present invention and are considered
within the scope of the present invention.
[0066] Metal brazing can also be utilized to attach superabrasive
particles to a segment blank or to attach a segment blank to a
support substrate. Metal brazing techniques are known in the art.
For example, in fabricating a diamond particle abrasive segment,
the process can include mixing diamond particles (e.g., 40/50 U.S.
mesh grit) with a suitable metal support matrix (bond) powder
(e.g., cobalt powder of 1.5 micrometer in size). The mixture is
then compressed in a mold to form a desired shape. This "green"
form of the tool can then be consolidated by sintering at a
temperature between 700-1200 degrees C. to form a single body with
a plurality of abrasive particles disposed therein. Finally, the
consolidated body can be attached (e.g., by brazing) to a segment
blank. Many other exemplary uses of this technology are known to
those having ordinary skill in the art. It should also be noted
that various sintering methods can also be utilized to attach the
abrasive layer to the segment blank. Suitable sintering methods
will be easily appreciated by one of ordinary skill in the art
having possession of this disclosure.
[0067] The abrasive layer can also be attached to a segment blank
by way of known electroplating and/or electrodeposition processes.
As an example of a suitable method for positioning and retaining
abrasive materials prior to and during the electrodeposition
process, a mold can be used that includes an insulating material
that can effectively prevent the accumulation of electrodeposited
material on the molding surface. Abrasive particles can be held on
the molding surface of the mold during electrodeposition. As such,
the accumulation of electrodeposited material can be prevented from
occurring on the particle tips and the working surface of the pad
conditioner substrate. Such techniques are described in U.S. patent
application Ser. No. 11/292,938, filed Dec. 2, 2005, which is
hereby incorporated herein by reference.
[0068] One or more apertures can extend through the insulating
material to allow for circulation of an electrolytic fluid from an
area outside the mold through the mold and to the surface of the
pad conditioner substrate in order to facilitate electrodeposition.
Such circulation can be advantageous as it is generally necessary
to keep a sufficient concentration of ions in an electrolytic fluid
at the location of electrodeposition. Other well known techniques
can also be utilized, it being understood that the above-provided
example is only one of many suitable techniques.
EXAMPLES
[0069] The following examples present various methods for making
the pad conditioners of the present invention. Such examples are
illustrative only, and no limitation on the present invention is to
be thereby realized.
Example 1
[0070] A segment blank is formed by arranging smooth diamond
particles (e.g. 50/60 mesh) on a stainless steel flat mold (also, a
slightly convex or contoured mold can be utilized) having a layer
of adhesive (e.g. acrylic). A hard rubber material is used to press
individual diamond particles into the adhesive while tips of the
particle are leveled by the flat mold. A mixture of epoxy and
hardener is then poured onto the particles protruding outside the
adhesive (a containment ring oriented outside the mold can retain
the epoxy). After curing, the mold is then removed and the adhesive
is peeled away. The resulting segment blank contains smooth diamond
particles protruding outside a solidified epoxy substrate.
Example 2
[0071] A segment blank is formed by arranging 80/90 mesh broken
single crystal diamond particles and brazing the diamond particles
to a stainless steel substrate. The resulting segment blank
contains rough diamond particle protruding from a solidified braze
alloy.
Example 3
[0072] A composite design combining the embodiments of Example 1
and Example 2 discussed above. Segment blanks from Examples 1 and 2
are arranged on a temporary substrate and a flat plate is used to
level the superabrasive particle tips of the segment blanks. While
these tips are leveled, the bases of the segment blanks are secured
with an epoxy resin.
Example 4
[0073] Two types of segment blanks are formed by brazing diamond
particles with Nichrobraz LM on segment blank substrates. The
segment blank substrates are stainless steel (316), 20 mm in
diameter by 4 mm in thickness. Smooth-type segment blanks are made
with 60/70 mesh MBG-660 (Diamond Innovations product designation)
having blocky or smooth diamond particle shapes, and rough-type
segment blanks are made with 100/110 mesh MBG-620 having irregular
shaped diamond particles. The two types of segment blanks are
placed on a flat stainless steel substrate in an alternating
pattern with a molded ceramic spacer. A flat stainless steel plate
is pressed on the diamond tips to level the segment blanks to
within 20 microns. Epoxy is added to surround each segment blank,
and is UV cured to harden the matrix.
[0074] It is to be understood that the above-described arrangements
are only illustrative of the application of the principles of the
present invention. Numerous modifications and alternative
arrangements may be devised by those skilled in the art without
departing from the spirit and scope of the present invention and
any appended or following claims are intended to cover such
modifications and arrangements. Thus, while the present invention
has been described above with particularity and detail in
connection with what is presently deemed to be the most practical
and preferred embodiments of the invention, it will be apparent to
those of ordinary skill in the art that numerous modifications,
including, but not limited to, variations in size, materials,
shape, form, function and manner of operation, assembly and use may
be made without departing from the principles and concepts set
forth herein.
* * * * *