U.S. patent application number 15/671065 was filed with the patent office on 2018-06-28 for cmp pad dressers having leveled tips and associated methods.
The applicant listed for this patent is Chien-Min Sung. Invention is credited to Chien-Min Sung.
Application Number | 20180178346 15/671065 |
Document ID | / |
Family ID | 53044183 |
Filed Date | 2018-06-28 |
United States Patent
Application |
20180178346 |
Kind Code |
A1 |
Sung; Chien-Min |
June 28, 2018 |
CMP PAD DRESSERS HAVING LEVELED TIPS AND ASSOCIATED METHODS
Abstract
CMP pad dressers having leveled tips and associated methods are
provided. In one aspect, for example, a CMP pad dresser can include
a support substrate and a plurality of superabrasive particles
secured to the support substrate with each superabrasive particle
extending away from the support substrate to a protrusion distance,
where a highest protruding tip of each of the plurality of
superabrasive particles align along a designated profile with a tip
variation of from about 5 microns to about 100 microns.
Inventors: |
Sung; Chien-Min; (Tansui,
TW) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Sung; Chien-Min |
Tansui |
|
TW |
|
|
Family ID: |
53044183 |
Appl. No.: |
15/671065 |
Filed: |
August 7, 2017 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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14506476 |
Oct 3, 2014 |
9724802 |
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15671065 |
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13802112 |
Mar 13, 2013 |
9138862 |
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14506476 |
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13479148 |
May 23, 2012 |
8974270 |
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13802112 |
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13797704 |
Mar 12, 2013 |
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14506476 |
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12726786 |
Mar 18, 2010 |
8622787 |
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13797704 |
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12255823 |
Oct 22, 2008 |
8393934 |
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12726786 |
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12168110 |
Jul 5, 2008 |
8398466 |
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12255823 |
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11560817 |
Nov 16, 2006 |
7762872 |
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12726786 |
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11357713 |
Feb 17, 2006 |
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11560817 |
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11223786 |
Sep 9, 2005 |
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11560817 |
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12850747 |
Aug 5, 2010 |
8678878 |
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13797704 |
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13034213 |
Feb 24, 2011 |
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13797704 |
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61489074 |
May 23, 2011 |
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60976198 |
Sep 28, 2007 |
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60681798 |
May 16, 2005 |
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61246816 |
Sep 29, 2009 |
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61333162 |
May 10, 2010 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B24D 3/00 20130101; B24B
53/12 20130101; B24B 53/017 20130101 |
International
Class: |
B24B 53/017 20060101
B24B053/017; B24B 53/12 20060101 B24B053/12; B24D 3/00 20060101
B24D003/00 |
Claims
1. A CMP pad dresser, comprising: a support substrate; and a
plurality of superabrasive particles secured to the support
substrate with each superabrasive particle extending away from the
support substrate to a protrusion distance, wherein a highest
protruding tip of each of the plurality of superabrasive particles
align along a designated profile with a tip variation of from about
5 microns to about 100 microns.
2. The dresser of claim 1, wherein the highest protruding tip of
each of the plurality of superabrasive particles align along the
designated profile with a tip variation of from about 10 microns to
about 50 microns.
3. The dresser of claim 1, wherein the highest protruding tip of
each of the plurality of superabrasive particles align along the
designated profile with a tip variation of from about 20 microns to
about 40 microns.
4. The dresser of claim 1, wherein the highest protruding tip of
each of the plurality of superabrasive particles align along the
designated profile with a tip variation of less than about 20
microns.
5. The dresser of claim 1, wherein the protrusions of the plurality
of superabrasive particles produce cutting depths of less than
about 20 microns when used to abrade a CMP pad.
6. The dresser of claim 1, wherein the protrusions of the plurality
of superabrasive particles produce cutting depths of from about 1
micron to about 20 microns when used to abrade a CMP pad.
7. The dresser of claim 1, wherein the protrusions of the plurality
of superabrasive particles produce cutting depths of from about 10
microns to about 20 microns when used to abrade a CMP pad.
8. The dresser of claim 1, wherein the designated profile includes
a configuration selected from the group consisting of a plane, a
slope, a curved shape, a dome shape, and combinations thereof.
9. The dresser of claim 1, wherein the plurality of superabrasive
particles is arranged across the support substrate in a
predetermined pattern.
10. The dresser of claim 9, wherein the predetermined pattern
includes an even distribution of the plurality of superabrasive
particles spaced at a distance of from about 100 microns to about
800 microns.
11. A CMP pad dresser, comprising: a rigid support substrate; and a
monolayer of a plurality of superabrasive particles coupled to the
support substrate, wherein each superabrasive particle in the
monolayer extends away from the support substrate to a protrusion
distance, and wherein the difference in protrusion distance between
the highest protruding tip and the second highest protruding tip of
the monolayer of superabrasive particles is less than or equal to
about 50 microns, and the difference in protrusion distance between
the highest 1% of the protruding tips of the monolayer of
superabrasive particles are within about 80 microns or less.
12. The dresser of claim 11, wherein the difference in protrusion
distance between the highest protruding tip and the second highest
protruding tip is less than or equal to about 10 microns.
13. The dresser of claim 11, wherein the difference in protrusion
distance between the highest protruding tip and the second highest
protruding tip is less than or equal to about 10 microns.
14. The dresser of claim 11, wherein the difference in protrusion
distance between the highest protruding tip and the 10.sup.th
highest protruding tip is less than or equal to about 20
microns.
15. The dresser of claim 11, wherein the difference in protrusion
distance between the highest protruding tip and the 100.sup.th
highest protruding tip is less than or equal to about 40
microns.
16. A CMP pad dresser, comprising: a rigid support substrate; and a
monolayer of a plurality of superabrasive particles coupled to the
support substrate, wherein the plurality of superabrasive particles
includes a plurality of working superabrasive particles, such that
rotating the dresser against a CMP pad cuts asperities into the CMP
pad having a cutting depth of less than or equal to about 50
microns.
17. The dresser of claim 16, wherein the cutting depth is from
about 10 microns to about 50 microns.
18. The dresser of claim 16, wherein the plurality of working
superabrasive particles includes at least 100 working superabrasive
particles.
19. The dresser of claim 16, wherein the plurality of working
superabrasive particles includes at least 1000 working
superabrasive particles.
20. The dresser of claim 16, wherein the plurality of working
superabrasive particles includes from about 1000 to about 6000
working superabrasive particles.
21. The dresser of claim 16, wherein the plurality of working
superabrasive particles includes from about 2000 to about 5000
working superabrasive particles.
22. The dresser of claim 16, wherein the plurality of working
superabrasive particles include at least about 1000 working
superabrasive particles that protrude from the rigid support
substrate to distances within about 30 microns of one another.
23. A method of dressing a CMP pad, comprising: applying the CMP
pad dresser of claim 16 to a CMP pad; moving at least one of the
CMP pad or the CMP pad dresser with respect to one another to cut
asperities into the CMP pad having a cutting depth of from about 10
microns to about 50 microns.
24. A CMP pad dresser, comprising: a support substrate; and a
plurality of superabrasive particles secured to the support
substrate and positioned to engage and dress a CMP pad, wherein the
plurality of superabrasive particles cut to depths of less than 50
microns into a CMP pad during a dressing procedure.
Description
PRIORITY DATA
[0001] This application is a continuation of U.S. patent
application Ser. No. 14/506,476, filed Oct. 3, 2014, now issued as
U.S. Pat. No. 9,724,802, which is a continuation-in-part of U. S.
patent application Ser. No. 13/802,112, filed on Mar., 13, 2013,
which is a continuation-in-part of U.S. patent application Ser. No.
13/479,148, filed on May 23, 2012, which claims the benefit of U.
S. Provisional Patent Application Serial No. 61/489,074, filed on
May 23, 2011. U.S. patent application Ser. No. 14/506,476 is also a
continuation-in-part of U. S. patent application Ser. No.
13/797,704, filed Mar. 12, 2013, which is a continuation-in-part of
U.S. patent application Ser. No. 12/726,786, filed on Mar. 18,
2010, which is a is a continuation-in-part of U.S. patent
application Ser. No. 12/255,823, filed Oct. 22, 2008, which is a
continuation-in-part of U.S. patent application Ser. No.
12/168,110, filed on Jul. 5, 2008, which claims the benefit of U.S.
Provisional Patent Application Ser. No. 60/976,198, filed Sep. 28,
2007. U.S. patent application Ser. No. 12/726,786, filed on Mar.
18, 2010 is also a continuation-in-part of U.S. patent application
Ser. No. 11/560,817, filed Nov. 16, 2006, which is a
continuation-in-part of U.S. patent application Ser. No.
11/357,713, filed Feb. 17, 2006, which claims the benefit of U.S.
Provisional Patent Application Ser. No. 60/681,798, filed May 16,
2005. U.S. patent application Ser. No. 11/560,817 is additionally a
continuation-in-part of U.S. patent application Ser. No.
11/223,786, filed Sep. 9, 2005. U.S. patent application Ser. No.
13/797,704 is also a continuation-in-part of U.S. patent
application Ser. No. 12/850,747, filed Aug. 5, 2010, which claims
the benefit of U.S. Provisional Patent Application Ser. No.
61/246,816, filed on Sep. 29, 2009. U.S. patent application Ser.
No. 13/797,704 is further a continuation-in-part of U.S. patent
application Ser. No. 13/034,213, filed Feb. 24, 2011, which claims
the benefit of U.S. Provisional Patent Application Ser. No.
61/333,162, filed on May 10, 2010. Each of these applications is
incorporated herein by reference.
BACKGROUND OF THE INVENTION
[0002] 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
[0003] The present disclosure provides CMP pad dressers and
associated methods, including without limitation, methods directed
to the manufacture and use of such dressers. In one aspect, for
example, a CMP pad dresser can include a support substrate and a
plurality of superabrasive particles secured to the support
substrate with each superabrasive particle extending away from the
support substrate to a protrusion distance. The plurality of
superabrasive particles can be positioned such that the highest
protruding tip of each of the plurality of superabrasive particles
align along a designated profile with a tip variation of from about
5 microns to about 100 microns. In another aspect, the highest
protruding tip of each of the plurality of superabrasive particles
align along the designated profile with a tip variation of from
about 10 microns to about 50 microns. In yet another aspect, the
highest protruding tip of each of the plurality of superabrasive
particles align along the designated profile with a tip variation
of from about 20 microns to about 40 microns. In a further aspect,
the highest protruding tip of each of the plurality of
superabrasive particles align along the designated profile with a
tip variation of less than about 20 microns. The designated profile
can include any geometric configuration that can be useful in
dressing a CMP pad, and any such configuration is considered to be
within the present scope. Non-limiting examples can include a
plane, a slope, a curved shape, a dome shape, and the like,
including appropriate combinations thereof.
[0004] The positioning of superabrasive particles relative to the
support substrate can also be described in terms of the depths that
the superabrasive particles cut into a CMP pad when used to abrade
the CMP pad. In one aspect, for example, the protrusions of the
plurality of superabrasive particles produce cutting depths of less
than about 20 microns when used to abrade a CMP pad. In another
aspect, the protrusions of the plurality of superabrasive particles
produce cutting depths of from about 1 micron to about 20 microns
when used to abrade a CMP pad. In yet another aspect, the
protrusions of the plurality of superabrasive particles produce
cutting depths of from about 10 microns to about 20 microns when
used to abrade a CMP pad.
[0005] As another exemplary aspect of the present disclosure, a CMP
pad dresser can include a rigid support substrate and a monolayer
of a plurality of superabrasive particles coupled to the support
substrate, where each superabrasive particle in the monolayer
extends from the support substrate to a protrusion distance. In one
aspect, the difference in protrusion distance between the highest
protruding tip and the second highest protruding tip of the
monolayer of superabrasive particles is less than or equal to about
50 microns, and the difference in protrusion distance between the
highest 1% of the protruding tips of the monolayer of superabrasive
particles is within about 80 microns or less. In another aspect,
the difference in protrusion distance between the highest
protruding tip and the second highest protruding tip is less than
or equal to about 10 microns. In yet another aspect, the difference
in protrusion distance between the highest protruding tip and the
second highest protruding tip is less than or equal to about 10
microns. In a further aspect, the difference in protrusion distance
between the highest protruding tip and the 10.sup.th highest
protruding tip is less than or equal to about 20 microns. In yet
another aspect, the difference in protrusion distance between the
highest protruding tip and the 100.sup.th highest protruding tip is
less than or equal to about 40 microns.
[0006] As yet another exemplary aspect of the present disclosure, a
CMP pad dresser can include a rigid support substrate and a
monolayer of a plurality of superabrasive particles coupled to the
support substrate, where the plurality of superabrasive particles
includes a plurality of working superabrasive particles, such that
rotating the dresser against a CMP pad cuts asperities into the CMP
pad having a cutting depth of less than or equal to about 50
microns. In another aspect, the cutting depth is from about 10
microns to about 50 microns. In yet another aspect, the plurality
of working superabrasive particles includes at least 100 working
superabrasive particles. In a further aspect, the plurality of
working superabrasive particles includes at least 1000 working
superabrasive particles. In yet another aspect, the plurality of
working superabrasive particles includes from about 1000 to about
6000 working superabrasive particles. In another aspect, the
plurality of working superabrasive particles includes from about
2000 to about 5000 working superabrasive particles. In a further
aspect, the plurality of working superabrasive particles include at
least about 1000 working superabrasive particles that protrude from
the rigid support substrate to distances within about 30 microns of
one another.
[0007] As another exemplary aspect of the present disclosure, a
method of dressing a CMP pad can include applying a CMP pad dresser
to a CMP pad, and moving at least one of the CMP pad or the CMP pad
dresser with respect to one another to cut asperities into the CMP
pad having a cutting depth of from about 10 microns to about 50
microns.
[0008] As a further exemplary aspect of the present disclosure, a
CMP pad dresser is provided including a support substrate and a
plurality of superabrasive particles secured to the support
substrate and positioned to engage and dress a CMP pad, where the
plurality of superabrasive particles cut to depths of less than 50
microns into a CMP pad during a dressing procedure.
[0009] 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 the accompanying
claims, or may be learned by the practice of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] FIG. 1 is a schematic side view of a CMP pad dresser in
accordance with an embodiment of the present disclosure;
[0011] FIG. 2 is a schematic side view of a CMP pad dresser in
accordance with an embodiment of the present disclosure;
[0012] FIG. 3 is a schematic side view of a CMP pad dresser in
accordance with an embodiment of the present disclosure; and
[0013] FIG. 4 is a schematic side view of a CMP pad dresser in
accordance with an embodiment of the present disclosure.
[0014] It will be understood that the above figures are merely for
illustrative purposes in furthering an understanding of the
invention. Further, the figures are not drawn to scale, thus
dimensions, particle sizes, and other aspects may, and generally
are, exaggerated to make illustrations thereof clearer. Therefore,
departure can be made from the specific dimensions and aspects
shown in the figures in order to produce the heat spreaders of the
present invention.
DETAILED DESCRIPTION
[0015] Before the present invention is disclosed and described, it
is to be understood that this invention is not limited to the
particular structures, method 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.
[0016] It must be noted that, as used in this specification and the
appended claims, the singular forms "a," "an" and, "the" include
plural referents unless the context clearly dictates otherwise.
Thus, for example, reference to "a diamond particle" includes one
or more of such particles and reference to "the layer" includes
reference to one or more of such layers.
[0017] Definitions
[0018] In describing and claiming the present invention, the
following terminology will be used in accordance with the
definitions set forth below.
[0019] As used herein, the terms "conditioner" and "dresser" can be
used interchangeably, and refer to a tool used to condition or
dress a pad, such as a CMP pad.
[0020] As used herein, "superabrasive" may be used to refer to any
crystalline, or polycrystalline material, or mixture of such
materials that has a Mohr's hardness of about 8 or greater. In some
aspects, the Mohr's hardness may be about 9.5 or greater. In other
aspects, superabrasive materials can be materials having a Vicker's
hardness of about 4000 Kg/mm.sup.2 or greater. Suitable
superabrasive material examples can include, without limitation,
diamond, polycrystalline diamond (PCD), cubic boron nitride (cBN),
polycrystalline cubic boron nitride (PcBN), corundum and sapphire,
as well as other superabrasive materials known to those skilled in
the art. Superabrasive materials may be incorporated into various
tools in a variety of forms including particles, grits, films,
layers, pieces, segments, etc. While superabrasive materials are
very inert and thus difficult to form chemical bonds with, it is
known that certain reactive elements, such as chromium and titanium
are capable of chemically reacting with superabrasive materials at
certain temperatures.
[0021] As used herein, "particle" refers, when used in connection
with superabrasive particles, to a particulate form of
superabrasive particle. Such particles may take a variety of
shapes, including round, oblong, square, euhedral, etc., can be
either single crystal or polycrystalline, and can have a number of
mesh sizes. As is known in the art, "mesh" refers to the number of
holes per unit area, as in the case of U.S. meshes. All mesh sizes
referred to herein are U.S. mesh unless otherwise indicated.
Further, mesh sizes are generally understood to indicate an average
mesh size of a given collection of particles since each particle
within a particular "mesh size" may actually vary over a small
distribution of sizes, unless noted otherwise.
[0022] As used herein, "working superabrasive particles" are
superabrasive particles that cut or otherwise deform a CMP pad
during a dressing or conditioning procedure. This action can remove
debris from the surface, it can deform the surface either
elastically or plastically, or it can create a groove or asperity
in the surface of the CMP pad. In one specific aspect, a working
superabrasive particle can cut deeper than about 10 microns into a
CMP pad during a dressing procedure.
[0023] As used herein, "non-working superabrasive particles" are
superabrasive particles in a CMP pad dresser that do not
significantly cut or deform the pad sufficient to remove debris
from the surface, deform the surface, or create grooves in the
surface.
[0024] As used herein, "overly-aggressive superabrasive particles"
are superabrasive particles in a CMP pad dresser that aggressively
dress or condition a CMP pad. In one aspect, aggressive
superabrasive particles are superabrasive particles that cut deeper
than about 50 microns into a CMP pad during a dressing procedure.
In another aspect, aggressive superabrasive particles are
superabrasive particles that remove at least 1/5 of the material
from the CMP pad. In yet another aspect, aggressive superabrasive
particles are superabrasive particles that remove at least 1/2 of
the material from the CMP pad.
[0025] As used herein, "working end" refers to an end of a particle
that is oriented towards the CMP pad and that during a dressing
operation makes contact with the pad. In many cases the working end
of a particle will be distal from a substrate to which the particle
is attached.
[0026] As used herein, cutting "tip" refers to a portion of a
cutting element or particle that protrudes the greatest distance
from the support substrate, e.g., that is the first portion of the
cutting element that contacts a CMP pad when in use. It is to be
understood that a cutting "tip" can include a planar surface, a
pointed surface, or an edge; so long as the planar surface, pointed
surface or edge of the cutting element is the first portion of the
cutting element that contacts a CMP pad from which material is to
be removed.
[0027] As used herein, "sharp portion" refers to any narrow portion
to which a crystal or particle may converge, including but not
limited to corners, apexes, ridges, edges, obelisks, and other
protrusions. In some cases, corners and/or apexes are formed at the
convergence of more than two faces of the particle or crystal, or
other body, disposed in intersecting planes. In other aspects,
edges and/or ridges may be formed at the convergence of two or at
least two faces of the particle or crystal, or other body, disposed
in intersecting planes. In some aspects, "sharp portion" can
include a portion that is broken, chipped, cracked, jagged, and the
like. In some aspects, degrees of sharpness can be correlated with
the geometric angle formed by the particle, crystal, or other body,
at the location in question. In some aspects, an angle of 90
degrees or less can be considered sharp. In other aspects, an angle
of 60 degrees or less can be considered sharp. In yet other
aspects, and angle of 45 degrees or less, or 30 degrees or less can
be considered to be sharp.
[0028] As used herein, cutting "edge" refers to a portion of a
cutting element or particle that includes some measurable width
across a portion that contacts and removes material from a
workpiece. As an exemplary illustration, a typical knife blade has
a cutting edge that extends longitudinally along the knife blade,
and the knife blade would have to be oriented transversely to a
workpiece to scrape or plane material from the workpiece in order
for the cutting "edge" of the knife blade to remove material from
the workpiece.
[0029] As used herein, "peripherally located," "peripheral
location," and the like, refer to any particle or other cutting
element of a dresser that is located in an area that originates at
the leading edge or outer rim of a dresser and extends inwardly
towards the center for up to about 90% of the radius of the
dresser. In some aspects, the area may extend inwardly from about
20% to 90% of the radius. In other aspects, the area may extend in
to about 50% of the radius. In yet another aspect, the area may
extend in to about 33% of the radius of a dresser (i.e. 66% away
from the center).
[0030] As used herein, "centrally located particle," "particle in a
central location," and the like refer to any particle or other
cutting element of a tool that is located in an area of the tool
that originates at a center point of the tool and extends outwardly
towards the tool's edge for up to about 90% of the radius of the
tool. In some aspects, the area may extend outwardly from about 20%
to about 90% of the radius. In other aspects, the area may extend
out to about 50% of the radius. In yet another aspect, the area may
extend out to about 33% of the radius of a tool.
[0031] As used herein, "attitude" refers to the position or
arrangement of a superabrasive particle in relation to a defined
surface, such as a substrate to which it is attached, or a CMP pad
to which it is to be applied during a work operation. For example,
a superabrasive particle can have an attitude that provides a
specific portion of the particle in orientation toward a CMP
pad.
[0032] As used herein, "leading edge" refers to the edge of a CMP
pad dresser that is a frontal edge based on the direction that the
CMP pad is moving, or the direction that the pad is moving, or
both. Notably, in some aspects, the leading edge may be considered
to encompass not only the area specifically at the edge of a
dresser, but may also include portions of the dresser which extend
slightly inward from the actual edge. In one aspect, the leading
edge may be located along an outer edge of the CMP pad dresser. In
another aspect, the CMP pad dresser may be configured with a
pattern of abrasive particles that provides at least one effective
leading edge on a central or inner portion of the CMP pad dresser
working surface. In other words, a central or inner portion of the
dresser may be configured to provide a functional effect similar to
that of a leading edge on the outer edge of the dresser.
[0033] As used herein, the term "profile" and "geometric profile"
can be used interchangeably, and refer to a predetermined contour
above a support substrate to which a plurality of superabrasive
particles or other cutting elements are intended to align. Examples
of such profiles may include, without limitation, flat or planar
profiles, curved profiles, wavy profiles, convex profiles, concave
profiles, multi-tiered profiles, and the like, including
combinations thereof.
[0034] As used herein, "geometric configuration" refers to a shape
that is capable of being described in readily understood and
recognized mathematical terms. Examples of shapes qualifying as
"geometric configurations" include, without limitation, cubic
shapes, polyhedral (including regular polyhedral) shapes,
triangular shapes (including equilateral triangles, isosceles
triangles and three-dimensional triangular shapes), pyramidal
shapes, spheres, rectangles, "pie" shapes, wedge shapes, octagonal
shapes, circles, etc.
[0035] As used herein, "dressing segment" refers to a dressing or
conditioning element of a CMP pad dresser. In one aspect, dressing
segments are utilized to carry superabrasive particles having
leveled tips. Thus, in some cases superabrasive particles can be
introduced into a CMP pad dresser by the incorporation of multiple
dressing segments. It should be noted that a variety of techniques
of attaching the dressing segments to the substrates, and a variety
of techniques of attaching the superabrasive particles to the
dressing segments, are possible, all of which are considered to be
within the present scope. 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 dressing segment to a substrate
is discussed herein, the method of attachment discussed can also be
used to attach superabrasive particles to a dressing segment. For
any particular CMP pad dresser being discussed, however, it is
understood that attachment methods of the superabrasive particles
to the dressing segments can differ from, or can be the same as,
the method used to attach the dressing segments to the pad
conditioner substrate.
[0036] As used herein, "cutting element" describes a variety of
structures capable of removing (e.g., cutting) material from a CMP
pad. A cutting element can be 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, a
cutting element can also refer an individual particle that may have
only one cutting point, ridge or mesa formed thereon or
therein.
[0037] 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.
[0038] 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.
[0039] As used herein, "mechanical bond" and "mechanical bonding"
may be used interchangeably, and refer to a bond interface between
two objects or layers formed primarily by frictional forces. In
some cases the frictional forces between the bonded objects may be
increased by expanding the contacting surface areas between the
objects, and by imposing other specific geometrical and physical
configurations, such as substantially surrounding one object with
another.
[0040] As used herein, "sintering" refers to the joining of two or
more individual particles to form a continuous solid mass. The
process of sintering involves the consolidation of particles to at
least partially eliminate voids between particles. Sintering may
occur in either metal or carbonaceous particles, such as diamond.
Sintering of metal particles occurs at various temperatures
depending on the composition of the material.
[0041] Sintering of diamond particles generally requires ultrahigh
pressures and the presence of a carbon solvent as a diamond
sintering aid. Sintering aids are often present to aid in the
sintering process and a portion of such may remain in the final
product.
[0042] The term "metallic" refers to both metals and metalloids.
Metals include those compounds typically considered metals found
within the transition metals, alkali and alkali earth metals.
Examples of metals are Ag, Au, Cu, Al, and Fe. Metalloids include
specifically Si, B, Ge, Sb, As, and Te. Metallic materials also
include alloys or mixtures that include metallic materials. Such
alloys or mixtures may further include additional additives. In the
present invention, carbide formers and carbon wetting agents may be
included as alloys or mixtures, but are not anticipated to be the
only metallic component. Examples of such carbide formers are Sc,
Y, Ti, Zr, Hf, V, Nb, Cr, Mo, Mn, Ta, W, and Tc. Examples of carbon
wetting agents are Co, Ni, Mn, and Cr.
[0043] As used herein, "infiltrating" refers to a situation where a
material is heated to its melting point and then flows as a liquid
through the interstitial voids between particles.
[0044] As used herein, the terms "substrate" and "support
substrate" can be used interchangeably, and refer a portion of a
pad conditioner that supports superabrasive materials, and to which
abrasive materials and/or superabrasive segments that carry
abrasive materials may be affixed. Substrates can have a variety of
shapes, thicknesses, and/or materials that are capable of
supporting abrasive materials in a manner that is sufficient to
provide a CMP pad dresser 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 thereof. Further, the substrate
may include a material that aids in attaching abrasive materials to
the substrate, including, without limitation, brazing alloy
material, sintering aids and the like.
[0045] 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. For
example, an object that is "substantially" enclosed would mean that
the object is either completely enclosed or nearly completely
enclosed. The exact allowable degree of deviation from absolute
completeness may in some cases depend on 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.
[0046] 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. For example, a composition that is "substantially
free of" particles would either completely lack particles, or so
nearly completely lack particles that the effect would be the same
as if it completely lacked particles. In other words, a composition
that is "substantially free of" an ingredient or element may still
actually contain such item as long as there is no measurable effect
thereof.
[0047] As used herein, the term "about" is used to provide
flexibility to a numerical range endpoint by providing that a given
value may be "a little above" or "a little below" the endpoint.
However, it is to be understood that even when the term "about" is
used in the present specification in connection with a specific
numerical value, that support for the exact numerical value recited
apart from the "about" terminology is also provided.
[0048] In this disclosure, "comprises," "comprising," "containing"
and "having" and the like can have the meaning ascribed to them in
U.S. Patent law and can mean "includes," "including," and the like,
and are generally interpreted to be open ended terms. The terms
"consisting of" or "consists of" are closed terms, and include only
the components, structures, steps, or the like specifically listed
in conjunction with such terms, as well as that which is in
accordance with U.S. Patent law. "Consisting essentially of" or
"consists essentially of" have the meaning generally ascribed to
them by U.S. Patent law. In particular, such terms are generally
closed terms, with the exception of allowing inclusion of
additional items, materials, components, steps, or elements, that
do not materially affect the basic and novel characteristics or
function of the item(s) used in connection therewith. For example,
trace elements present in a composition, but not affecting the
compositions nature or characteristics would be permissible if
present under the "consisting essentially of" language, even though
not expressly recited in a list of items following such
terminology. When using an open ended term, like "comprising" or
"including," it is understood that direct support should be
afforded also to "consisting essentially of" language as well as
"consisting of" language as if stated explicitly and vice
versa.
[0049] 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.
[0050] Concentrations, amounts, 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. As an illustration, a
numerical range of "about 1 to about 5" should be interpreted to
include not only the explicitly recited values of about 1 to about
5, 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., as well as 1, 2, 3, 4, and 5,
individually. This same principle applies to ranges reciting only
one numerical value as a minimum or a maximum. Furthermore, such an
interpretation should apply regardless of the breadth of the range
or the characteristics being described.
[0051] The Invention
[0052] The present disclosure generally provides CMP pad dressers,
methods associated with pad conditioning (e.g., smoothing,
polishing, dressing), and the CMP polishing of a work piece. Pad
conditioners according to aspects of the present disclosure can be
advantageously utilized, for example, in dressing CMP pads that are
used in polishing, finishing or otherwise affecting semiconductor
materials. Specifically, in some aspects the present disclosure
concerns CMP pad dressers having superabrasive particles with
substantially leveled tips. In other aspects, the present CMP pad
dressers can have superabrasive particles that are aligned across a
designated profile, and as such, are "leveled" with respect to that
profile. Traditional CMP pad dresser manufacturing methods, even
many of those describing techniques for leveling superabrasive
particle tips prior to fixation, generally contain significant
variation in tip height across the surface of the dresser that is
not accounted for by an intended tip alignment profile. Often, the
superabrasive particles are affixed to the CMP pad dresser support
in a manner that disrupts any leveling that has occurred. For
example, fixation techniques that utilize high heat and/or pressure
can cause warping of the dresser support as the dresser cools.
Thus, unless steps are taken to avoid such warpage, superabrasive
particles are not maintained in their leveled state following
cooling of the dresser. This can be particularly problematic with
brazing techniques.
[0053] A CMP pad dresser can be used to dress or condition a CMP
pad by removing dirt and debris (i.e. deglazing the pad), as well
as opening up asperities in the pad surface to capture and hold
chemical slurry during a polishing procedure. As has been
described, due to difficulties associated with superabrasive
particle leveling in many traditional manufacturing processes, only
a small percentage of superabrasive particles in a typical CMP pad
dresser are positioned so as to penetrate or cut into a CMP pad. As
this small percentage of superabrasive particles become worn,
plastic deformation of the CMP pad becomes large relative to the
amount of CMP of pad that is cut. Consequently, the pad becomes
highly deformed and accumulated with dirt. As a result the
polishing rate of the CMP pad declines, and the scratch rate of the
wafer or work piece increases.
[0054] CMP pads are typically made of a relatively soft polymer,
such as, for example, polyurethane. As the CMP pad is engaged by
the CMP pad dresser, the polymer material is deformed first by
elastic strain and then by plastic strain. Eventually, the strain
energy in the deformed material exceeds the bond energy density
(i.e. the hardness of the pad) and the polymer material ruptures.
Thus, the function of superabrasive particles in the CMP pad
dresser is to dress the CMP pad material by breaking polymeric
bonds through this deformation process. It should be noted that
sharp superabrasive particle tips can penetrate the CMP pad
material without causing excessive deformation. As such, the
sharpness of a superabrasive particle can be defined as being
inverse to the deformed volume prior to rupture. In other words,
the smaller the volume of deformation prior to cutting, the sharper
the cutting tip. This deformation information can be used to
determine the sharpness of superabrasive particles in the CMP pad
dresser.
[0055] Additionally, a superabrasive particle having a tip with
smaller tip radius, such as would be the case with a broken corner,
can cut more cleanly through the CMP pad with less deformation as
compared to a superabrasive particle having a larger tip radius.
Consequently, an irregularly shaped superabrasive particle tip can
be sharper than a euhedral superabrasive corner having an obtuse
angle relative to the CMP pad. This also applies to the difference
between a superabrasive particle corner as compared with a
superabrasive particle face.
[0056] It is thus noted that sharp superabrasive particle tips can
cut CMP pad materials with less deformation and material strain.
Conversely, a dull superabrasive particle may deform but not cut
the CMP pad material because the strain energy does not exceed the
bond energy density of the polymeric material. As the tips of such
particles are worn, the contact area between the polymeric material
and the particles increase. This increase in contact area results
in an increase in the deformation volume of the pad. Due to the
increased strain energy required for the polymeric material to
rupture with such an increased deformation volume, the number of
superabrasive particles cutting the polymeric material will
decrease in relation to the degree of dulling during a CMP
process.
[0057] CMP pad dressing can also be affected by the proportion of
superabrasive particles in the CMP pad dresser that are working and
the proportion that are overly-aggressively cutting. As an example,
a typical CMP pad dresser can have greater than 10,000
superabrasive particles. Of these 10,000 particles, in some cases
there may only be a few working superabrasive particles that are
actually able to cut the CMP pad. Additionally, out of these few
working superabrasive particles, there may be a smaller proportion
of overly-aggressive superabrasive particles that cut over 50% of
the entire pad that is consumed during conditioning, and in some
cases can remove more that 25% of the total pad material. This
uneven work load distribution can cause erratic CMP performance,
and can result in over consumption of the CMP pad, chipping of the
overly-aggressive superabrasive particles that can scratch the
wafer, unpredictable wafer removal rates, uneven wafer surface
planarization, shortened CMP pad dresser life, compaction of the
CMP pad with debris, and the like. Such effects can greatly lower
the yield of wafers or work pieces processed under these
conditions. A more effective normalization of work load
distribution across the surface of the CMP pad dresser can lead to
a more uniformly deglazed pad and more uniform pad asperities.
[0058] The present CMP pad dressers include a layer of
superabrasive particles having substantially leveled tips across
the working surface of the finished CMP pad dresser. A variety of
techniques can be utilized to maintain tip leveling, and any such
technique is considered to be within the present scope. A few
non-limiting examples of such techniques are described below. It is
intended that the term "leveling" with respect to superabrasive
particles can refer to superabrasive particles that are leveled
with respect to a planar profile, as well as to superabrasive
particles that are aligned along a designated profile that is
non-planar. In the latter case, "leveling" would thus describe the
alignment of the superabrasive particles along the designated
profile. So in the case of a profile having a dome-shape, leveled
superabrasive particles would be particles that were in alignment
with the profile.
[0059] Furthermore, superabrasive tip alignment can additionally be
described in terms of height distribution, or in some cases
protrusion distance from the support substrate that is represented
by a height distribution across the plurality of superabrasive
particles. An even height distribution of superabrasive particles
may function to more effectively preserve the integrity of the CMP
pad dresser as compared to CMP pad dressers lacking such an even
height distribution. Similarly, a plurality of superabrasive
particles can be described as extending away from a support
substrate to a predetermined height, represented by a protrusion
distance from the substrate, where the predetermined heights of the
particles align along a designated profile. Thus, the actual
distribution of protrusion distances across the plurality of
superabrasive particles in a finished dresser can be compared
against the designated profile to determine the variance, or degree
of "leveling" achieved.
[0060] In one aspect, for example, a CMP pad dresser is provided
including a support substrate and a plurality of superabrasive
particles secured to the support substrate, with each superabrasive
particle extending away from the support substrate to a protrusion
distance, where the highest protruding tip of each of the plurality
of superabrasive particles align along a designated profile. While
it is intended that the tips of the superabrasive particles align
along the designated profile, some level of deviation may occur.
These deviations may be a result of the design or manufacturing
process of the tool. Given the wide variety of sizes of
superabrasive particles that may potentially be utilized in a given
tool, such deviations may be highly dependent on a particular
application. Also, when referring to the designated profile, it
should be noted that the term "tip" is intended to include the
highest protruding point of a superabrasive particle, whether that
point be an apex, an edge, or a face.
[0061] As such, in one aspect the plurality of superabrasive
particles are arranged such that their tips vary from the
designated profile by from about 1 micron to about 150 microns. In
another aspect, the plurality of superabrasive particles are
arranged such that their tips vary from the designated profile by
from about 5 microns to about 100 microns. In yet another aspect,
the plurality of superabrasive particles are arranged such that
their tips vary from the designated profile by from about 10
microns to about 75 microns. In a further aspect, the plurality of
superabrasive particles are arranged such that their tips vary from
the designated profile by from about 10 microns to about 50
microns. In another aspect, the plurality of sup erabrasive
particles are arranged such that their tips vary from the
designated profile by from about 50 microns to about 150 microns.
In yet another aspect, the plurality of sup erabrasive particles
are arranged such that their tips vary from the designated profile
by from about 20 microns to about 100 microns. In a further aspect,
the plurality of superabrasive particles are arranged such that
their tips vary from the designated profile by from about 20
microns to about 50 microns. In another aspect, the plurality of
sup erabrasive particles are arranged such that their tips vary
from the designated profile by from about 20 microns to about 40
microns. Additionally, in one aspect, the plurality of
superabrasive particles are arranged such that their tips vary from
the designated profile by less than about 20 microns. In another
aspect the plurality of superabrasive particles are arranged such
that their tips vary from the designated profile by less than about
10 microns. In yet another aspect, the plurality of superabrasive
particles are arranged such that their tips vary from the
designated profile by less than about 5 microns. In yet another
aspect, the plurality of superabrasive particles are arranged such
that their tips vary from the designated profile by less than about
1 micron. In a further aspect, a majority of the plurality of
superabrasive particles are arranges such that their tips vary from
the designated profile to less than about 10% of the average size
of the superabrasive particles.
[0062] In another aspect, each of the plurality of superabrasive
particles can be defined by a protrusion distance from an exposed
surface of a binding material from which they protrude to a
predetermined height. Though the predetermined height may vary
between tool applications, in one aspect the predetermined height
may be greater than about 20 microns. In another aspect the
variation from the predetermined height may be from about 1 micron
to about 20 microns. In yet another aspect the variation from the
predetermined height may be from about 5 microns to about 20
microns. In a further aspect the variation from the predetermined
height may be from about 10 microns to about 20 microns.
Superabrasive particles may also be arranged with respect to
arrangement or distribution, attitude, size, etc. Furthermore, the
distribution of protrusion of the plurality of superabrasive
particles is reflected in the depth that the particles cut into a
CMP pad.
[0063] As such, in one specific aspect the predetermined height or
protrusion distance may produce a cutting depth of less than about
20 microns when used to dress a CMP pad. In another specific
aspect, the predetermined height or protrusion distance may produce
a cutting depth of from about 1 micron to about 20 microns when
used to dress a CMP pad. In yet another specific aspect, the
predetermined height or protrusion distance may produce a cutting
depth of from about 10 micron to about 20 microns when used to
dress a CMP pad. It should also be noted that the leveling of
superabrasive particles to a predetermined height may be dependent
on superabrasive particle spacing. In other words, the farther
superabrasive particles are separated, the more the impinging
forces will affect each superabrasive particle. As such, patterns
with increased spacing between the superabrasive particles may
benefit from a smaller variation from predetermined height.
[0064] In one specific example, a plurality of cutting elements
such as superabrasive particles can protrude to a predetermined
height above a binding material such as, for example, a solidified
organic material layer. Though any predetermined height that would
be useful in an abrading or cutting tool would be considered to be
within the presently claimed scope, in one specific aspect the
predetermined height may produce a cutting depth of less than about
20 microns when used to abrade a workpiece. In another specific
aspect, the predetermined height may produce a cutting depth of
from about 1 micron to about 20 microns when used to abrade a
workpiece. In yet another specific aspect, the predetermined height
may produce a cutting depth of from about 10 micron to about 20
microns when used to abrade a workpiece. In yet another aspect, the
predetermined height may produce a depth of up to or more than 50
or 100 microns.
[0065] As a further example, it may also be beneficial for the
cutting elements to protrude from the binding material, for
example, solidified organic material layer to a predetermined
height or series of heights that is/are along a designated profile.
Numerous configurations for designated profiles are possible,
depending on the particular use of the abrading tool. In one
aspect, the designated profile may be a plane. In planar profiles,
the highest protruding points of the cutting elements are intended
to be substantially level. It is important to point out that,
though it is preferred that these points align with the designated
profile, there may be some height deviation between cutting
elements that occur due to limitations inherent in the
manufacturing process.
[0066] In addition to planar profiles, in another aspect the
designated profile has a slope. Tools having sloping surfaces may
function to more evenly spread the frictional forces impinging
thereon across the cutting elements, particularly for rotating
tools such as disk sanders and CMP pad dressers. The greater
downward force applied by higher central portions of the tool may
offset the higher rotational velocity at the periphery, thus
reducing the mechanical stress experienced by cutting elements in
that location. As such, the slope may be continuous from a central
point of the tool to a peripheral point, or the slope may be
discontinuous, and thus be present on only a portion of the tool.
Similarly, a given tool may have a single slope or multiple slopes.
In certain aspects, the tool may slope in a direction from a
central point to a peripheral point, or it may slope from a
peripheral point to a central point.
[0067] Various slopes are contemplated that may provide a benefit
to solidified organic material layer tools. It is not intended that
the claims of the present invention be limited as to specific
slopes, as a variety of slopes in numerous different tools are
possible. In one aspect, however, a CMP pad dresser may benefit
from an average slope of 1/1000 from the center to the
periphery.
[0068] As a variation on tools having a slope, in certain aspects
the designated profile may have a curved shape. One specific
example of a curved shape is a dome shape tool. Such curved
profiles function in a similar manner to the sloped surfaces. Tools
may include such curved profiles in order to more effectively
distribute the frictional forces between all of the cutting
elements, thus reducing failures of individual particles and
prolonging the life of the tool.
[0069] Furthermore, in some aspects the determination of the
distance that the tips of the cutting elements extend from a binder
material, such as an organic binder, can also be affected by
considering how much of the cutting elements extend above the
binder compared to how much of the cutting elements remain
submerged beneath the binder surface. In one aspect, a ratio of an
amount the cutting elements protrude above the binder to an amount
submerged beneath the binder is about 4 to 1. In another aspect,
about 2/3 of the cutting elements are submerged, with about 1/3
being exposed above the binder. Other ratios are also possible,
from a 20 to 1 ratio to about 0.2 to 1, inclusive of ranges
therebetween.
[0070] As a non-limiting example, in one aspect a CMP pad dresser
can include a support substrate, such as a rigid support substrate,
and a monolayer of a plurality of superabrasive particles coupled
to the support substrate, where the plurality of superabrasive
particles includes a plurality of working superabrasive particles.
In use the dresser can be engaged against a CMP pad and cut
asperities into the CMP pad having a cutting depth of less than or
equal to about 50 microns. In another aspect, the cutting depth is
from about 10 microns to about 50 microns. Additionally, in one
aspect the plurality of working superabrasive particles includes at
least 100 working superabrasive particles, at least 300 working
superabrasive particles, or at least 500 working superabrasive
particles. In another aspect, the plurality of working
superabrasive particles includes at least 1000 working
superabrasive particles. In yet another aspect, the plurality of
working superabrasive particles includes from about 1000 to about
6000 working superabrasive particles. In a further aspect, the
plurality of working superabrasive particles includes from about
2000 to about 5000 working superabrasive particles. In yet another
aspect, the plurality of working superabrasive particles include at
least about 1000 working superabrasive particles that protrude from
the rigid support substrate to distances within about 30 microns of
one another.
[0071] It is noted that, in some cases, the number of working
superabrasive particles can be determined by observing edge or tip
wear after use in a dressing operation. As such, in one aspect a
CMP pad dresser can have greater than about 300 superabrasive
particles with worn tips or edges following a CMP pad dressing
procedure. In another aspect, a CMP pad dresser can have greater
than about 500 superabrasive particles with worn tips or edges
following a CMP pad dressing procedure. In a further aspect, a CMP
pad dresser can have greater than about 1000 superabrasive
particles with worn tips or edges following a CMP pad dressing
procedure.
[0072] In one example, superabrasive particle tips can be described
in terms of the distance that each superabrasive particle protrudes
from the binding material, or matrix layer. The difference in
protrusion distance between the highest protruding tip and the next
highest protruding tip of the monolayer of superabrasive particles
is described as the protrusion difference. In one aspect, the
protrusion difference can be less than or equal to about 50
microns. In another aspect, the protrusion difference can be less
than or equal to about 20 microns. In a further aspect, the
protrusion difference can be less than or equal to about 10
microns. It is noted that the term "protrusion difference" can also
be used to describe the difference in protrusion distance between
any two or more superabrasive particles.
[0073] In another aspect, and in addition to the protrusion
difference between the highest two protruding tips, the difference
in protrusion distance between the highest 10 protruding tips of
the monolayer of superabrasive particles are within about 30
microns or less. In yet another aspect, the difference in
protrusion distance between the highest 10 protruding tips of the
monolayer of superabrasive particles are within about 20 microns or
less.
[0074] Additionally, in some aspects the difference in protrusion
distance between the highest 1% of the protruding tips of the first
monolayer of superabrasive particles can be within about 80 microns
or less. In other words, for the 1% of the plurality of
superabrasive particles that have the highest protruding tips, the
variance in protrusion distance for that 1% is less than or equal
to about 80 microns. For example, the two highest protruding
superabrasive particle tips protrude to within about 10 microns or
less of each other, and in addition, the highest protruding 1% of
superabrasive particle tips protrude to within about 80 microns or
less of each other. In yet another aspect, the difference in
protrusion distance between the highest 1% of the protruding tips
of the monolayer of superabrasive particles are within about 60
microns or less. In yet another aspect, the difference in
protrusion distance between the highest 1% of the protruding tips
of the monolayer of superabrasive particles are within about 40
microns or less.
[0075] It is noted that the recited protrusion distances can
include a distribution across the entire monolayer surface or a
discrete area or segment of the monolayer. For example, the highest
1% of protruding tips can be located around the periphery of the
monolayer. In one aspect, for example, substantially all of the
asperities are cut in the CMP pad by superabrasive particles
located at a peripheral location of the dresser. In another aspect,
the peripheral location extends from an outer edge of the dresser
inwardly toward a center point of the dresser for up to about 90%
of the dresser radius. In yet another aspect, the peripheral
location extends from an outer edge of the dresser inwardly toward
a center point of the dresser for up to about 50% of the dresser
radius. In a further aspect, the peripheral location extends from
an outer edge of the dresser inwardly toward a center point of the
dresser for up to about 33% of the dresser radius. Additionally, in
some aspects, substantially all of the superabrasive particles are
located at a peripheral location of the dresser. In other aspects,
substantially all of the superabrasive particles are arranged in
uniform predetermined pattern at a peripheral location of the
dresser.
[0076] In another example, discrete regions of leveled
superabrasive particle tips can be located within a larger area of
superabrasive particles having a lower protrusion distance than the
leveled portion. It is also contemplated that the monolayer can
include multiple regions or segments of superabrasive particles
that are leveled as described, within a larger area of
superabrasive particles having a lower protrusion distance.
[0077] Thus, the relative leveling of the monolayer of
superabrasive particles can greatly affect the morphology and
distribution of asperities cut into the CMP pad by the dresser. For
example, in one aspect, the monolayer is leveled such that rotating
the dresser against the CMP cuts asperities having a maximum
cutting depth of about 80 microns. In another aspect, the monolayer
is leveled such that rotating the dresser against the CMP cuts
asperities having a maximum cutting depth of about 60 microns. In
yet another aspect, the monolayer is leveled such that rotating the
dresser against the CMP cuts asperities having a maximum cutting
depth of about 40 microns. By forming pointed asperities, the
contact pressure between the work piece and the CMP pad is
increased, thus improving the polishing characteristics of the pad.
As these pointed regions begin to flatten, the contact pressure
begins to decrease, and slurry located therebetween is less
effectively pressed against the work piece. In some aspects it can
be beneficial for the contact area between the pad and the wafer to
be less than or equal to about 1% of the total wafer surface area
facing the pad. In other aspects, it can be beneficial for the
contact area between the pad and the wafer to be less than or equal
to about 0.1% of the total wafer surface area facing the pad. This
small contact area is due to the wafer being perched on the contact
points of the asperities. During the polishing process, the sharp
tips of the asperities become worn, thus increasing the contact
area and decreasing the contact pressure to a point whereby the
slurry abrasives do not effectively abrade the wafer. At this point
the removal rate of material from the wafer drops, and the pad
needs to be redressed to resharpen the asperities.
[0078] Additionally, the load placed on the CMP pad by the dresser
can affect the morphology of the spacers, such as, in some cases,
the asperity depth. The load can be adjusted for a given dresser to
adjust penetration depth. In one aspect, for example, the load can
be from about 0.1 Kg to about 60 Kg. In other aspects, the load can
be from about 2 Kg to about 20 Kg. In further aspects, the load may
be from about 6 Kg to about 12 Kg. In some aspects the load may be
Kg/m2. For example, in one aspect an 11.5 Kg load can allow a
material removal rate from the wafer of about 200 microns per hour
for Cu layers. In a related example, an 11.5 Kg load can allow a
material removal rate from the wafer of about 100 microns per hour
for oxides. In many cases, a lower load can be used in order to
minimize the superabrasive particle damage (e.g., less than or
equal to about 2 Kg).
[0079] Furthermore, leveling of the tips of the superabrasive
particles in the monolayer allows differing amounts of
superabrasive particles to actually cut asperities into the pad. In
one aspect, for example, the tips are leveled such that at least
100 tips of the plurality of superabrasive particles cut asperities
into the CMP pad as the dresser is rotated. In another aspect, the
tips are leveled such that at least 50 tips of the plurality of
superabrasive particles cut asperities into the CMP pad as the
dresser is rotated. In a further aspect, the tips are leveled such
that at least 25 tips of the plurality of superabrasive particles
cut asperities into the CMP pad as the dresser is rotated.
[0080] Additionally, various methods can be utilized to measure
superabrasive particle tip height to determine the difference in
protrusion distance between tips. As such, any method for making
such a determination is considered to be within the present scope.
It should be noted that for the purposes of the present disclosure,
the term "protrusion" refers to the height of a particle relative
to some reference point. Techniques for such measurements can
include direct measurements of the tip heights relative to a
reference point such as, for example, the highest particle tip, a
surface of a rigid support, the bottom surface of the matrix, etc.
Measurements of particle height from the surface of the matrix
material can be problematic, however, due to the irregular nature
of such materials due to wicking around the superabrasive
particles. In those cases whereby the matrix material is uniform,
such a surface may be used to determine particle height.
Additionally, a relative protrusion or height difference between
two particles would be the difference in the heights between these
particles measured from a common reference point. Furthermore, in
some cases the superabrasive particles may lie along a slope,
curvature, or some other arrangement that is not parallel to the
underlying support, such as, for example, a metal support layer. In
these cases, the protrusion height would be normalized against the
slope, curvature, or other arrangement so that the relative
protrusion height difference between particles can be measured in
the absence of the slope, curvature, etc. It should be noted that
superabrasive particle tip height leveling can, in some cases, be
independent from the positioning or patterning of the superabrasive
particles across the surface of the dresser.
[0081] One example of a direct measurement technique can include an
optical scanning process to evaluate superabrasive particle tip
positions. In one such process, an optical scanner can scan the
surface of the CMP pad dresser to determine the height of the
superabrasive particle tips relative to a fixed point. For example,
the scanner can scan downward in space toward the dresser until the
highest tip is located. The highest tip can then be set to the
reference point, and the scanner can continue scanning in a
direction toward the dresser measuring the distance from the
reference point to each superabrasive particle tip across the
surface of the dresser. Accordingly, the difference in protrusion
distance between all of the superabrasive particles across the
dresser can be directly measured.
[0082] Furthermore, measurement techniques can also include
indirect measurements, such as, for example, applying the diamond
monolayer to a deformable substrate that deforms relative to the
protrusion distance of the particle tips. The diamond monolayer can
be pressed into the deformable substrate and/or moved across the
deformable substrate to form a scratch pattern therein. Tip height
can thus be extrapolated from such indirect measurements.
[0083] Numerous configurations for designated profiles are possible
depending on the particular use of the abrading tool, and all such
designated profiles are considered to be within the present scope.
In one aspect, for example, the designated profile can be a plane.
In planar profiles, the highest protruding points of the
superabrasive particles are intended to be substantially level in
the traditional sense. It is important to point out that, though it
is preferred that these points align with the designated profile,
there may be some height deviation between superabrasive particles
that occur due to limitations inherent in the manufacturing
process.
[0084] In addition to planar profiles, in another aspect of the
present invention the designated profile has a slope. Tools having
sloping surfaces may function to more evenly spread the frictional
forces impinging thereon across the superabrasive particles,
particularly for rotating tools such as disk sanders and CMP pad
dressers. The greater downward force applied by higher central
portions of the tool may offset the higher rotational velocity at
the periphery, thus reducing the mechanical stress experienced by
superabrasive particles in that location. As such, the slope may be
continuous from a central point of the tool to a peripheral point,
or the slope may be discontinuous, and thus be present on only a
portion of the tool. Similarly, a given tool may have a single
slope or multiple slopes. In certain aspects, the tool may slope in
a direction from a central point to a peripheral point, or it may
slope from a peripheral point to a central point. Various slopes
are contemplated that may provide a benefit to solidified organic
material layer tools. It is not intended that the claims of the
present invention be limited as to specific slopes, as a variety of
slopes in numerous different tools are possible. In one aspect,
however, a CMP pad dresser may benefit from an average slope of
1/1000 from the center to the periphery.
[0085] Furthermore, in certain aspects the designated profile may
have a curved shape. One specific example of a curved shape is a
dome shape CMP pad dresser. Such curved profiles function in a
similar manner to the sloped surfaces. CMP pad dressers may include
such curved profiles in order to more effectively distribute the
frictional forces between all of the superabrasive particles, thus
reducing failures of individual particles and prolonging the life
of the dresser. Also, CMP pad dressers can have designated profiles
that combine any of a plane, a slope, a curved shape, a dome shape,
and the like, into a variety of complex profiles.
[0086] In another aspect of the present disclosure, a CMP pad
dresser can include a support substrate, such as a rigid support
substrate, and a monolayer of a plurality of superabrasive
particles coupled to the support substrate, where each
superabrasive particle in the monolayer extends away from the
support substrate to a protrusion distance, and where the
difference in protrusion distance between the highest protruding
tip and the second highest protruding tip of the monolayer of
superabrasive particles is less than or equal to about 50 microns.
Additionally, the difference in protrusion distance between the
highest 1% of the protruding tips of the monolayer of superabrasive
particles are within about 80 microns or less. In another aspect,
the difference in protrusion distance between the highest
protruding tip and the second highest protruding tip is less than
or equal to about 10 microns. In yet another aspect, the difference
in protrusion distance between the highest protruding tip and the
second highest protruding tip is less than or equal to about 10
microns. In a further aspect, the difference in protrusion distance
between the highest protruding tip and the 10.sup.th highest
protruding tip is less than or equal to about 20 microns. In yet
another aspect, the difference in protrusion distance between the
highest protruding tip and the 100.sup.th highest protruding tip is
less than or equal to about 40 microns.
[0087] In another aspect of the present disclosure, a CMP pad
dresser is provided including a support substrate and a plurality
of superabrasive particles secured to the support substrate and
positioned to engage and dress a CMP pad, where the plurality of
superabrasive particles cut to depths of less than 50 microns into
a CMP pad during a dressing procedure.
[0088] In a further aspect, a method of dressing a CMP pad is
provided. Such a method can include applying a CMP pad dresser to a
CMP pad, and moving at least one of the CMP pad or the CMP pad
dresser with respect to one another to cut asperities into the CMP
pad having a cutting depth of from about 10 microns to about 50
microns. As one non-limiting example, an exemplary CMP pad can
include a support substrate and a monolayer of a plurality of
superabrasive particles coupled to the support substrate, where the
plurality of superabrasive particles includes a plurality of
working superabrasive particles.
[0089] In one exemplary aspect, as is shown in FIG. 1, a CMP pad
dresser 100 includes a monolayer of a plurality of superabrasive
particles 102 coupled to a support substrate 104 with, for example,
a binding material 105. Each superabrasive particle in the
monolayer protrudes to a protrusion distance from the support
substrate. The difference in protrusion distance 106 between the
highest protruding tip 108 and the next highest protruding tip 110
of the monolayer of superabrasive particles is described as the
protrusion difference. In one aspect, the protrusion difference can
be less than or equal to about 50 microns. In another aspect, the
protrusion difference can be less than or equal to about 20
microns. In a further aspect, the protrusion difference can be less
than or equal to about 10 microns. It is noted that the term
"protrusion difference" can also be used to describe the difference
in protraction distance between any two or more superabrasive
particles.
[0090] A variety of materials are contemplated for use as
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.
[0091] It is intended that the scope of the present disclosure
include superabrasive particles of all conceivable sizes that would
be useful in dressing a CMP pad. Aspects of the present disclosure,
however, specifically allow the retention of superabrasive
particles in a CMP pad dresser of sizes that have not previously
been feasible for use in metal tools made using traditional
techniques with particles exposed and arranged in a pattern. In one
aspect, superabrasive particles may range in size from about 30
microns to about 250 microns. In another aspect, superabrasive
particles may range in size from about 100 microns to about 200
microns. In yet another aspect, superabrasive particles can range
from 100 microns to 150 microns. Additionally, various diamond
particles sizes can be used, including mesh sizes such as 10/20,
30/40, 80/90, 90/100, 100/120, 120/140, 140/170, 170/200, 200/230,
230/270, 270/325, and 325/400.
[0092] Additionally, the plurality the superabrasive particles can
be oriented so as to affect dressing performance of a CMP pad.
Orienting the superabrasive particles in a specific attitude in
relation to the CMP pad to be dressed creates different asperities
in the pad surface, thus altering the performance of the CMP pad.
Different asperities retain slurry in different manners and thus
polish a workpiece differently according to asperity depth, width,
density, etc. The superabrasive particles of a CMP pad dresser can
be oriented according to the desired polishing characteristics of
the CMP pad. For example, if the superabrasive particles
predominantly have an apex oriented towards the CMP pad, the
asperities of the pad will be narrow and deep. The advantages of
narrow and deep asperities are that the pad can better retain the
polishing slurry, and thus the polishing rate of the wafer
increases. However, the increased polishing rate may also increase
the wear rate of the superabrasive particles. As such, wear rate
may vary depending on the attitude of the superabrasive particles,
and therefore, the orientation of each superabrasive particle may
be considered when designing a device with desired performance
characteristics. Generally speaking, superabrasive particle
attitudes that provide higher dressing rates (i.e. deeper
penetration into a pad) also wear particles out at a higher
rate.
[0093] In contrast, if the superabrasive particles are oriented
with a face towards the pad, the resulting asperities may polish at
a lower rate. The face of the particle is generally thought to be
more durable, but does not typically cut deep and narrow asperities
in the pad, but rather asperities that are shallow and broad.
Therefore the face portion of a particle will dress a CMP pad at a
reduced rate compared to the apex portion of a particle, but the
superabrasive particle will wear at a much lower rate.
[0094] The edge portions of a superabrasive particle have dressing
and wear characteristics that are between those of the face and
apex portions. It has been thought that if the edge portion is
utilized to dress a CMP pad, the asperities are not as deep or
narrow as those dressed with an apex portion, but may provide
asperities having desirable intermediate characteristics. Further,
the edge portion of the particle does not wear at such a high rate
as that of an apex.
[0095] In one aspect, the plurality of superabrasive particles are
substantially all configured in an attitude having either an apex
portion or an edge portion oriented toward a pad to be dressed. In
another aspect, the plurality of superabrasive particles are
substantially all configured in an attitude having either an edge
portion or a face portion oriented toward a pad to be dressed. In
yet another aspect, the plurality of superabrasive particles can be
configured in an attitude having a sharp portion oriented towards a
pad to be dressed. In a further aspect, the plurality of
superabrasive particles can be configured in an attitude having an
apex portion oriented towards a pad to be dressed.
[0096] A CMP pad dresser having a substantially leveled tip
arrangements can have a low scratch rate because superabrasive
particles are less likely to pull out of the matrix layer due to
their more uniform protrusion distribution compared to traditional
dressers. Additionally, the more uniform protrusion distributions
of such a dressers allows the conditioning of CMP pads in such a
manner as to facilitate good polishing rates while at the same time
extending the effective working life of the dresser. These benefits
can be affected by, for example, uniform asperity spacing and size
distribution in the CMP pad.
[0097] CMP pad dressers having substantially leveled or leveled
superabrasive particle tips can be made using various manufacturing
techniques, and any such technique is considered to be within the
present scope. The following description provides a few
non-limiting descriptions of such exemplary processes.
[0098] In one aspect, for example, a CMP pad dresser can be made
using a brazing process, and as such would generally include a
support substrate and a plurality of superabrasive particles
coupled to the support substrate by a metal or metal alloy braze
material. As has been described, traditional brazing techniques
create warpage in the dresser as the braze material cools. As such,
superabrasive particle tips that were leveled prior to brazing are
substantially misaligned in the manufactured dresser. Therefore,
steps to minimize or eliminate the warpage must be taken when using
a braze process in order to maintain tip leveling. Various
techniques to minimize or eliminate warpage are contemplated, and
any such technique is considered to be within the present
scope.
[0099] As one general example, a CMP pad dresser can be made in at
least a two stage process, where the first stage is performed in a
manner that minimizes perturbations of the leveled tips in a
process that would normally significantly move the superabrasive
tips out of a leveled arrangement, such as, for example, by
brazing. The second stage of the process can further enhance the
leveling of superabrasive particle tips across the CMP pad dresser.
Other examples may include utilizing lower temperature alloys,
using slow temperature ramping in heating and/or cooling of the
support substrate, using additional mechanical support to firmly
hold the support substrate from moving when warpage occurs, and the
like.
[0100] Warpage can also be minimized or eliminated through the
structural design of the dresser. For example, in one aspect a CMP
pad dresser can include a first monolayer of superabrasive
particles disposed on one side of a metal support layer and a
second monolayer of superabrasive particles disposed on the metal
support layer on an opposite side from the first monolayer. The
superabrasive particles of the second monolayer are positioned to
have substantially the same distribution as the superabrasive
particles of the first monolayer. A rigid support is coupled to the
second monolayer of superabrasive particles opposite the first
monolayer to provide support to the dresser.
[0101] As is shown in FIG. 2, for example, a first monolayer of
superabrasive particles 202 is arranged on a surface of a support
substrate 204. A second monolayer of superabrasive particles 206 is
arranged on the support substrate 204 on a side that is opposite to
the first monolayer. As is discussed further below, in some cases
the first and second monolayers of superabrasive particles can be
arranged such that corresponding superabrasive particles across the
support layer are in substantial alignment, as is shown in FIG. 2.
In other cases, the superabrasive particles of the first and second
monolayers can be arranged in a substantially similar distribution,
but may or may not be substantially aligned with one another across
the support substrate.
[0102] The disposition of a monolayer of superabrasive particles on
each side of the support substrate thus moderates the thermal
shrinkage from the brazing temperature that would otherwise buckle
a distribution of superabrasive particles arranged on just one
side. By applying a monolayer to each side of the support
substrate, warping forces such as thermal movement and pressure can
be equalized or substantially equalized from both sides. As such,
the warpage of the support substrate can be minimized. In other
words, the forces responsible for warping are applied substantially
equally to each side of the support substrate and can thus at least
partially cancel one another out, thus minimizing warpage that can
otherwise occur. In some aspects, the superabrasive particles
making up the monolayers on each side of the support substrate can
have matching configurations, patterns, or orientations to one
another. In this way there can be a substantially matching spatial
arrangement of superabrasive particles on each side of the support
substrate. In another aspect, the configurations, patterns, or
orientations can be different or varied from one another, or may be
partially matching. In yet another aspect, the patterned placement
of the superabrasive particles on one side of the support substrate
can be substantially aligned with the pattern of superabrasive
particles on the other side of the support substrate so that
particle locations match one another. In some aspects, there can be
a direct correspondence between the spatial positioning of
superabrasive particles on one side of the support substrate and
the spatial positioning of superabrasive particles on the other
side of the metal support substrate. In another aspect, the
patterns of superabrasive particles may match or substantially
match one another, but may be offset on opposite sides of the
support substrate so that particle locations do not match one
another.
[0103] Accordingly, minimizing the warpage of the support substrate
can maintain a greater degree of leveling of superabrasive particle
tips in the finished tool. When heat and/or pressure are used to
make a superabrasive tool, warpage of the support substrate can
cause great variations in tip height level, even for those
particles that were leveled prior to heating and/or applying
pressure. In one aspect, distributing the warpage forces equally or
substantially equally on both sides of a support substrate through
the arrangement of the superabrasive particles can effectively
cancel forces on opposing sides and thus greatly reduce the degree
of warping occurring in the support substrate, thus also minimizing
the relative height movement of the superabrasive particles
relative to one another. In other aspects, CMP pad dressers can be
made using processes that do not utilized high pressure and/or high
temperature.
[0104] The support substrate can be any material capable of
supporting the diamond monolayer during tool formation. Such
materials can include, without limitation, metal materials, metal
alloy materials, braze alloy materials, ceramic materials,
composites, and the like.
[0105] In one aspect, the superabrasive particles can be arranged
into a predetermined pattern. Such a pattern can be a uniformly
distributed pattern or a non-uniformly distributed pattern.
Additionally, a variety of techniques are contemplated to
facilitate the arrangement of superabrasive particles into a
predetermined pattern. Predetermined is understood to mean a
non-random pattern that has been determined prior to arranging the
superabrasive particles. In one aspect, a predetermined pattern can
also apply to a predetermined spacing between particles.
Non-limiting examples of such techniques include arrangement by a
template, arrangement using spots of adhesives, arrangement on a
first substrate followed by a pattern specific transfer from the
first substrate to the support substrate, and the like, including
combinations thereof. The superabrasive particles from either of
the monolayers can be temporarily held in position in the
predetermined pattern using a variety of techniques, including,
without limitation, adhesives, dimpled locations on the metal
support matrix, a supporting compound such as, for example, a wax,
and the like, including combinations thereof. In one specific
aspect, the superabrasive particles can be temporarily coupled to
the support substrate using an adhesive that then volatilizes away
and is eliminated during construction of the dresser.
[0106] In one aspect, the predetermined pattern can be a uniformly
distributed grid. In another aspect, the predetermined pattern can
be an annular configuration having a central region devoid of
superabrasive particles. In one specific aspect, the annular
configuration can include an annular ring. In another specific
aspect, the annular configuration can include a portion of an
annular ring. In yet another aspect, an annular configuration can
include one or more concentric annular rings nested inside one
another.
[0107] In other aspects, the monolayer distribution can be discrete
radial regions, spiral regions, and the like.
[0108] In another aspect, as is shown in FIG. 3, a first monolayer
of superabrasive particles 302 is arranged on a surface of a
support substrate 304. A second monolayer of superabrasive
particles 306 is arranged on the support substrate 304 on a side
that is opposite to the first monolayer. A bonding material 308
secures the first monolayer and the second monolayer to the support
substrate 34. The bonding material can be any material capable of
securing the first and second monolayer to the support substrate.
In some aspect, the bonding material can be the same for securing
the first monolayer and the second monolayer, while in other
aspects the bonding material can be different for securing the
first monolayer and the second monolayer.
[0109] It is noted that the various descriptions of materials,
attachment techniques, and the like, can be generally applicable to
any CMP pad dresser design to which such materials, techniques, and
the like are applicable. For example, a material that can be used
to secure a superabrasive particle to a substrate can be used in
both dual monolayer and single monolayer dresser designs.
[0110] Accordingly, the bonding material can be any material
capable of securing superabrasive particles therein. Non-limiting
examples of bonding materials include metal brazes, metal braze
alloys, organic matrix materials, sintered materials, electroplated
materials, and the like, including combinations thereof.
[0111] In one aspect, for example, the superabrasive particles can
be brazed to the support substrate, and thus the bonding material
can be a metal braze or metal braze alloy. Metal brazing techniques
are known in the art. A green braze material can be applied to the
support substrate on or around the superabrasive particles. The
metal braze can be applied in any known configuration, including
braze sheets, powders, pastes, sprays, and the like, including
combinations thereof. Once applied to the support substrate, the
braze can be heated and melted to coat at least a portion of the
support substrate and to bond the superabrasive particles. The
heating temperature can vary depending on the braze material used,
but in one aspect can be from about 700.degree. C. to about
1200.degree. C.
[0112] In one non-limiting example, the superabrasive particles can
be bonded to the support substrate by brazing with a nickel-based
alloy containing chromium. In another example, the brazing can
include pressing the superabrasive particles with a flat ceramic
material that cannot be bonded to the braze in order to level the
superabrasive particle tips. Various braze alloys are contemplated,
including non-limiting examples such as BNi.sub.2, BNi.sub.7, and
the like.
[0113] Additionally, in one aspect superabrasive particles can be
coupled to the support substrate by an electrodeposition process,
and thus the bonding material can be an electrodeposited metal
material. 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. Superabrasive
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.
[0114] In another aspect, the superabrasive particles can be bonded
to the support substrate by sintering, and thus the bonding
material can include a sintering material. For example, the bonding
of the superabrasive particles to the support substrate can include
disposing a sintering compound on the support substrate in contact
with the plurality of superabrasive particles, and sintering the
sintering compound to bond the superabrasive particles to the
support substrate. Suitable sintering methods will be readily
appreciated by one of ordinary skill in the art having possession
of this disclosure. Basically, a sintering compound is applied
around the superabrasive particles and in contact with the support
substrate. The sintering compound can be any known sintering
material that can be used to secure superabrasive particles to a
substrate. Non-limiting examples of such materials can include
metal and metal alloy powders, ceramic powders, and the like. One
specific non-limiting example of a sintering compound is cobalt
powder.
[0115] Once the sintering compound has been applied around the
superabrasive particles and to the support substrate, heat and in
some cases pressure can be applied to cause sintering to occur. In
some aspects, a braze or braze alloy can be infiltrated into the
sintering compound during bonding to further strengthen the bonding
material matrix.
[0116] In yet another aspect, sintering can be used to sinter the
plurality of superabrasive particles into a CMP pad dresser, where
the support substrate is the sintering material. In this case, the
above recited procedure can be repeated without the use of a
support substrate.
[0117] In another aspect, heat and pressure can be applied to bond
the plurality of superabrasive particles directly into the support
substrate. Thus, upon the application of heat and pressure, the
support substrate can be softened or partially melted. The
superabrasive particles are then pressed into the support
substrate. A planar leveling surface can be used to apply pressure
to the monolayer of superabrasive particles to thus maintain the
level nature of the superabrasive particle tips as the
superabrasive particles are pressed into the support substrate.
Pressure can be maintained upon the support substrate and
superabrasive particles until cooled, thus minimizing warping.
[0118] In yet another aspect, as is shown in FIG. 4, a dual
monolayer CMP pad dresser can include a first monolayer of
superabrasive particles 402 and a second monolayer of superabrasive
particles 406 coupled to a support substrate 404. The superabrasive
particles can be coupled to the support substrate directly or via a
bonding material. The second monolayer of superabrasive particles
406 is coupled to a second support substrate 408. A portion of the
second support substrate is shown removed in FIG. 4 to expose the
second monolayer. The second support substrate 408 can facilitate
handling and use of the CMP pad dresser. By bonding the
superabrasive particles of the second monolayer to the second
support substrate, the first monolayer of superabrasive particles
remains exposed for CMP pad conditioning operations.
[0119] The second support substrate can be made from any material
compatible with the abrading or dressing process. Such materials
can include polymeric materials, metal materials, ceramic
materials, glasses, composites, and the like. In one aspect, the
second support substrate can be a polymeric material and the second
monolayer of superabrasive particles can be embedded therein using
heat, pressure, adhesives, etc. In some aspects, the second support
substrate can be a non-polymeric material such as a metal layer. In
such cases, the superabrasive particles can be bonded to the second
support substrate by adhesive attachment, soldering, brazing,
electroplating, and the like. For brazing techniques, care can be
taken to minimize or eliminate warpage in the substrate during the
heating and cooling process. In another aspect, one or more
magnetic elements can be placed into the second support substrate
to attract and hold the CMP pad dresser in place, thus forming a
temporary attachment. An optional locking mechanism can be utilized
to further immobilize the CMP pad dresser to the second support
substrate during use. In some aspects the second support substrate
can include surface features to hold the dresser in place during
rotational movement against a CMP pad. The second support substrate
can have approximately the same diameter as the metal support
layer, a larger diameter than the metal support layer, or, in some
cases, a smaller diameter than the metal support layer.
[0120] In another aspect, a CMP pad dresser can be comprised of a
plurality of dressing segments having a plurality of leveled
superabrasive particles tips, where the plurality of dressing
segments are held in place by a rigid support or support substrate.
Such a design allows a plurality of smaller dressing segments to be
manufactured having precisely leveled tips. Smaller diameter
support layers in these dressing segments can be made by processes
involving heat and/or pressure with less warpage due to their
smaller size. For example, a 4 inch diameter metal disc can exhibit
greater warping due to brazing as compared to a 0.5 inch diameter
metal disc. Thus thermal distortion and particle floating problems
are decreased. A plurality of such dressing segments can then be
coupled to a larger diameter support substrate by processes that do
not introduce significant warpage, such as bonding in an organic
material. Such dressing segments can have one or more layer(s) of
superabrasive particles coupled to a support layer. In one aspect,
a segment can have a single layer of superabrasive particles
coupled to a support layer. In another aspect, a segment can have a
layer of superabrasive particles coupled to each side of a support
layer, as has been described herein. Thus, this process allows the
manufacture of CMP pad dressers that can have precise tip
protrusion tolerances. Additionally, in one aspect, each dressing
segment can have at least three superabrasive particles that
protrude to the greatest extent. If the three highest protruding
superabrasive particles on every dressing segment are leveled
across the entire support substrate, a CMP pad dresser is made
having very precise tip leveling across the entire surface. If, for
example, ten dressing segments are used to make the CMP pad
dresser, then the highest protruding thirty superabrasive particles
in the tool will have effectively the same protrusion distance and
be substantially leveled. Various additional details regarding
dressing segments are detailed in U.S. patent application Ser. No.
13/034,213, filed Feb. 24, 2011, which is hereby incorporated
herein by reference.
[0121] Various organic materials are contemplated for use as a
support substrate, and/or to secure a second monolayer of
superabrasive particles and/or the dressing segments to the support
substrate. 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 material can be an epoxy resin. In
another aspect, the organic material can be a polyimide resin. In
yet another aspect, the organic material can be a polyurethane
resin.
[0122] Additionally, so-called "reverse casting" methods can be
used to accurately orient and attach the dressing segments to the
support substrate. Such methods can include initially securing the
plurality of dressing segments to a substrate using a "mask"
material. The portions of the dressing segments protruding from the
mask material can then be attached to the rigid support using the
methods discussed herein, after which (or during which), the
masking material can be removed.
[0123] When an organic material is utilized, methods of curing the
organic material 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.
[0124] In one aspect of the present invention, the organic material
can 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.
[0125] 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.
[0126] 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.
[0127] Additionally, in one aspect a coupling agent or an
organometallic compound may be coated onto the surface of a
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, 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 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.
[0128] 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.
[0129] In other aspects of the present disclosure, superabrasive
particle tips can be leveled by reducing the protrusions of
particles that are outside of the desired tolerance range. Once
such particles are identified, various techniques can be utilized
to reduce such protrusions. In one aspect, for example, mechanical
abrasion of the dresser can reduce the protruding particles. In
another aspect, a vibration tool can be used to individually break
such particles. In yet another aspect, a laser such as a Nd:YAG
laser can be used to disrupt such particles.
[0130] In yet a further aspect of the present disclosure, a CMP pad
dresser can include a plurality of superabrasive particles arranged
as a working surface, where the difference in protrusion distance
between the highest protruding tip and the second highest
protruding tip of the first monolayer of superabrasive particles is
less than or equal to about 20 microns, and where the difference in
protrusion distance between the highest 1% of the protruding tips
of the first monolayer of superabrasive particles, excluding the
highest protruding tip, are within about 80 microns.
[0131] In another aspect, a CMP pad dresser can include a plurality
of superabrasive particles arranged as a working surface, where the
difference in protrusion distance between the highest protruding
tip and the second highest protruding tip is less than or equal to
about 10 microns, the difference in protrusion distance between the
highest protruding tip and the 10.sup.th highest protruding tip is
less than or equal to about 20 microns, the difference in
protrusion distance between the highest protruding tip and the
100.sup.th highest protruding tip is less than or equal to about 40
microns, and the highest protruding tip has a protrusion distance
of greater than or equal to about 50 microns.
[0132] It is noted that, while the above disclosure refers
primarily to CMP pad dressers, other precision grinding and/or
abrading tools are considered to be within the present scope. As
such, the techniques and teaching disclosed herein can additionally
be applied to such tools.
[0133] Additionally, it is noted that traditional CMP processing
techniques, including pad dressing, has limited the critical
dimension of integrated circuits. The presently disclosed CMP
dressing devices and techniques can, however, allows processing of
wafers having integrated circuit critical dimensions of less than
or equal to 45 nm, 32 nm, 28 nm, 22 nm, or less.
[0134] Of course, 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 the appended 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.
* * * * *