U.S. patent application number 13/326464 was filed with the patent office on 2012-07-05 for cmp pad conditioning tool.
This patent application is currently assigned to DIAMOND INNOVATIONS, INC.. Invention is credited to Thomas Easley, James Graham, Charles Rarey, Gary Ruland, Mark Schweizer.
Application Number | 20120171935 13/326464 |
Document ID | / |
Family ID | 45953217 |
Filed Date | 2012-07-05 |
United States Patent
Application |
20120171935 |
Kind Code |
A1 |
Ruland; Gary ; et
al. |
July 5, 2012 |
CMP PAD Conditioning Tool
Abstract
The present disclosure provides a CMP pad conditioning tool with
at least one integral abrasive protrusion. The present disclosure
further provides a method for preparing this CMP pad conditioning
tool, along with a method for using said tool to condition a CMP
pad.
Inventors: |
Ruland; Gary; (Warner
Robins, GA) ; Schweizer; Mark; (Powell, OH) ;
Rarey; Charles; (Lewis Center, OH) ; Easley;
Thomas; (Bexley, OH) ; Graham; James;
(Gahanna, OH) |
Assignee: |
DIAMOND INNOVATIONS, INC.
Worthington
OH
|
Family ID: |
45953217 |
Appl. No.: |
13/326464 |
Filed: |
December 15, 2011 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61424870 |
Dec 20, 2010 |
|
|
|
Current U.S.
Class: |
451/56 ;
451/443 |
Current CPC
Class: |
B24D 3/06 20130101; B24D
7/02 20130101; B24D 18/0054 20130101; B24B 53/017 20130101; B24D
3/34 20130101; B24D 18/0009 20130101; B24D 18/0027 20130101 |
Class at
Publication: |
451/56 ;
451/443 |
International
Class: |
B24B 53/017 20120101
B24B053/017; B24B 1/00 20060101 B24B001/00 |
Claims
1. A chemical mechanical polishing ("CMP") pad conditioning tool
for conditioning a surface of a CMP pad, said tool comprising a
tool body having a tool face, said tool body and tool face
comprising a material selected from the group of polycrystalline
diamond, polycrystalline cubic boron nitride, boron carbide,
silicon carbide, and combinations thereof; said tool face having at
least one integral abrasive protrusion extending from said tool
face said at least one integral abrasive protrusion having at least
one side angled at greater than 90 degrees relative to the surface
of the CMP pad to be conditioned.
2. The CMP pad conditioning tool of claim 1, wherein the at least
one integral abrasive protrusion comprises an array of integral
abrasive protrusions.
3. The CMP pad conditioning tool of claim 2, wherein the array of
integral abrasive protrusions comprises an array of pyramids,
tetrahedra, cones, or other polygons, provided that said pyramids,
tetrahedral, cones, or other polygons have at least one side angled
at greater than 90 degrees relative to the surface of the CMP pad
to be conditioned.
4. The CMP pad conditioning tool of claim 1, wherein the material
selected from the group of polycrystalline diamond, polycrystalline
cubic boron nitride, boron carbide, silicon carbide, and
combinations thereof is a SiC-diamond composite.
5. A method for conditioning a surface of a CMP pad, said process
comprising a) contacting the surface of said CMP pad with a CMP pad
conditioning tool comprising: a tool body having a tool face, said
tool body and tool face comprising a material selected from the
group of polycrystalline diamond, polycrystalline cubic boron
nitride, boron carbide, silicon carbide, and combinations thereof;
said tool face having at least one integral abrasive protrusion
extending from said tool face; said at least one integral abrasive
protrusion having at least one side angled at greater than 90
degrees relative to the surface of the CMP pad contacted by said
CMP pad conditioning tool; and b) conditioning the surface of said
CMP pad, optionally in the presence of one or more conditioning
fluids.
6. The method according to claim 5, wherein the at least one
integral abrasive protrusion comprises an array of integral
abrasive protrusions.
7. The method according to claim 6, wherein the array of integral
abrasive protrusions comprises an array of pyramids, tetrahedra,
cones, or other polygons, provided that said pyramids, tetrahedra,
cones, or other polygons have at least one side angled at greater
than 90 degrees relative to the surface of the CMP pad contacted by
said CMP pad conditioning tool.
8. The method according to claim 5, wherein the material selected
from the group of polycrystalline diamond, polycrystalline cubic
boron nitride, boron carbide, silicon carbide, and combinations
thereof is a SiC-diamond composite.
9. A system for conditioning a surface of a CMP pad, said system
comprising at least one CMP pad conditioning system, adapted to
receive at least one CMP pad; and at least one CMP pad conditioning
tool, said tool comprising a tool body having a tool face, said
tool body and tool face comprising a material selected from the
group of polycrystalline diamond, polycrystalline cubic boron
nitride, boron carbide, silicon carbide, and combinations thereof;
said tool face having at least one integral abrasive protrusion
extending from said tool face; and said at least one integral
abrasive protrusion having at least one side angled at greater than
90 degrees relative to the surface of the CMP pad to be
conditioned.
10. The system according to claim 9, wherein the at least one
integral abrasive protrusion comprises an array of integral
abrasive protrusions.
11. The system according to claim 10, wherein the array of integral
abrasive protrusions comprises an array of pyramids, tetrahedra,
cones, or other polygons, provided that said pyramids, tetrahedra,
cones, or other polygons have at least one side angled at greater
than 90 degrees relative to the surface of the CMP pad contacted by
said CMP pad conditioning tool.
12. The system according to claim 9, wherein the material selected
from the group of polycrystalline diamond, polycrystalline cubic
boron nitride, boron carbide, silicon carbide, and combinations
thereof is a SiC-diamond composite.
13. A method for preparing a CMP pad conditioning tool for
conditioning a surface of a CMP pad, said method comprising
machining a surface of a blank comprising a material selected from
the group of polycrystalline diamond, polycrystalline cubic boron
nitride, boron carbide, silicon carbide, and combinations thereof
to produce a CMP pad conditioning tool according to claim 1.
14. The method according to claim 13, wherein said machining
results in a plurality of integral abrasive protrusions.
15. The method according to claim 14, wherein said plurality of
protrusions are a regular array of integral abrasive
protrusions.
16. The method of claim 13, wherein the machining method is wire
EDM.
17. The method of claim 13, wherein the machining method is plunge
EDM.
18. A method for preparing a CMP pad conditioning tool according to
claim 1, said method comprising: pressing a powder mixture
comprising about 90% diamond powder by weight, about 9.5% silicon
powder by weight, and about 0.5% Si.sub.3N.sub.4 by weight, into a
negative form, said negative form comprising a silicon mass, and
heating said powder and said mass under pressure, to produce the
CMP pad conditioning tool according to claim 1.
19. A method for preparing the CMP pad conditioning tool according
to claim 1, said method comprising: mixing a powder comprising
about 90% diamond powder by weight, about 9.5% silicon powder by
weight, and about 0.5% Si.sub.3N.sub.4 by weight, with a binder to
form a powder/binder mixture; pressing said powder/binder mixture
to form a preform, said preform having a preform face, said preform
face comprising at least one integral abrasive protrusion extending
from said preform face; heating said preform to a temperature and
in an atmosphere suitable for removing all of the binder from the
preform by incineration; and firing said preform at a temperature
of at least about 1000.degree. C. for at least about 5 minutes to
partially react the powder particles and form a porous rigid
preform.
20. The method according to claim 19, wherein the binder is
polyethyleneglycol or polyvinylalcohol.
21. The method according to claim 20, wherein the preform is fired
at a temperature of at least about 1450.degree. C. for at least
about 5 minutes.
22. The method according to claim 20, wherein said preform is fired
at a temperature of about 1300.degree. C. for about 5 minutes.
23. The method according to claim 19, further comprising heating
said porous rigid preform in an inert gas or under vacuum at a
second temperature; and contacting the rigid porous preform heated
to said second temperature with liquid silicon, so that said liquid
silicon infiltrates the preform and reacts with the diamond in the
preform to form SiC.
Description
TECHNICAL FIELD AND INDUSTRIAL APPLICABILITY
[0001] The present disclosure provides a novel tool and method for
reconditioning chemical mechanical polishing ("CMP") pads. The
present disclosure further includes methods for preparing the novel
tool described herein as well as methods for using it.
BACKGROUND OF THE INVENTION
[0002] CMP methods are well known in the art and are regularly used
to polish integrated circuit wafers. In a CMP process, polishing
reactants, abrasives, and carrier fluids are applied to the wafer
surface by a porous pad. Through a combination of chemical and
mechanical action, the pad resurfaces the wafer being polished,
such that a smooth wafer surface is obtained. In order to maintain
the utility of the CMP pad, it must be periodically reconditioned
to maintain uniform, repeatable polishing performance. This
reconditioning may use a pad conditioning tool to remove spent
reactants, abrasives, and polishing swarf.
[0003] Various CMP pad conditioning tools are known in the art as
well. Typically, these conditioning tools comprise abrasives held
randomly on a substrate by a bonding agent. U.S. Patent Publication
2009/0275274, for example, describes a conditioning tool comprising
abrasive grains fixed to the surface of a metal support with a
brazing metal. Similarly, U.S. Pat. No. 7,641,538 describes a CMP
pad conditioning tool comprising abrasive particles fixed to a
substrate using a brazing alloy and a sintered corrosion resistant
powder.
[0004] U.S. Patent publication 2010/0139174 describes a CMP
conditioning pad wherein abrasive particles are fixed to the
surface of a substrate using organic materials such as amino
resins, acrylate resins, polyester resins, polyurethane resins,
phenolic resins, etc. U.S. Patent publication 2009/0224370
describes growing CVD diamond on the surface of a substrate for the
preparation of a CMP conditioning tool and PCT/US2008/073823
discloses a CMP pad conditioning tool comprising abrasive grains
bound to a substrate using a brazing alloy prepared from a brazing
film.
[0005] Although the above described CMP pad conditioning tools have
been used extensively in reconditioning processes, the
above-described abrasives frequently present a non planar surface
that abrades and deforms the polishing pad in an irregular manner,
limiting control over the conditioning process. Moreover, many of
the above described CMP pad conditioning tools can release abrasive
particles or other contaminants onto the CMP pad as the result of a
failure in the bonding agent holding the abrasive particles to the
substrate. If the CMP pad containing the contaminants is then used
to polish an integrated circuit wafer, the wafer can be
damaged.
[0006] Therefore, what is needed is a CMP pad conditioner that does
not suffer from the above described defects.
SUMMARY OF THE INVENTION
[0007] The present disclosure provides a CMP pad conditioning tool
comprising a fully integral array of abrasive protrusions that
provide more complete control of the CMP pad reconditioning
process. These abrasive protrusions are integrally attached to a
substrate by high strength bonds that preclude abrasive particle
loss. The present disclosure further provides a method of producing
controlled single protrusions or arrays of controlled protrusions
in the CMP pad conditioning tool.
[0008] The present invention includes a chemical mechanical
polishing ("CMP") pad conditioning tool for conditioning a surface
of a CMP pad. The tool comprises a tool body having a tool face,
said tool body and tool face comprising a material selected from
the group of polycrystalline diamond, polycrystalline cubic boron
nitride, boron carbide, silicon carbide, and combinations thereof.
The tool face has at least one integral abrasive protrusion
extending from said tool face and the at least one integral
abrasive protrusion has at least one side angled at greater than 90
degrees relative to the surface of the CMP pad to be
conditioned.
[0009] In certain embodiments, the at least one integral abrasive
protrusion comprises an array of integral abrasive protrusions. In
particular embodiments, the array of integral abrasive protrusions
comprises an array of pyramids, tetrahedra, cones, or other
polygons, provided that the pyramids, tetrahedral, cones, or other
polygons have at least one side angled at greater than about 90
degrees relative to the surface of the CMP pad to be
conditioned.
[0010] In certain embodiments, the material is selected from the
group of polycrystalline diamond, polycrystalline cubic boron
nitride, boron carbide, silicon carbide, and combinations thereof.
In certain embodiments the material is a SiC-diamond composite.
[0011] The present invention further provides a method for
conditioning a surface of a CMP pad. This process comprises steps
a) and b). Step a) comprises contacting the surface of a CMP pad
with a CMP pad conditioning tool comprising a tool body having a
tool face, said tool body and tool face comprising a material
selected from the group of polycrystalline diamond, polycrystalline
cubic boron nitride, boron carbide, silicon carbide, and
combinations thereof; the tool face having at least one integral
abrasive protrusion extending from said tool face; and said at
least one integral abrasive protrusion having at least one side
angled at greater than about 90 degrees relative to the surface of
the CMP pad contacted by said CMP pad conditioning tool. Step b)
comprises conditioning the surface of said CMP pad, optionally, in
the presence of one or more conditioning fluids.
[0012] In certain embodiments, the at least one integral abrasive
protrusion comprises an array of integral abrasive protrusions. In
particular embodiments, the array of integral abrasive protrusions
comprises an array of pyramids, tetrahedra, cones, or other
polygons, provided that the pyramids, tetrahedra, cones, or other
polygons have at least one side angled at greater than about 90
degrees relative to the surface of the CMP pad contacted by the CMP
pad conditioning tool.
[0013] In certain embodiments, the material selected from the group
of polycrystalline diamond, polycrystalline cubic boron nitride,
boron carbide, silicon carbide, and combinations thereof is a
SiC-diamond composite.
[0014] The present invention further provides a system for
conditioning a surface of a CMP pad. The system comprises at least
one CMP pad conditioning system adapted to receive at least one CMP
pad; and at least one CMP pad conditioning tool comprising a tool
body having a tool face, said tool body and tool face comprising a
material selected from the group of polycrystalline diamond,
polycrystalline cubic boron nitride, boron carbide, silicon
carbide, and combinations thereof; said tool face having at least
one integral abrasive protrusion extending from said tool face; and
said at least one integral abrasive protrusion having at least one
side angled at greater than about 90 degrees relative to the
surface of the CMP pad to be conditioned.
[0015] In certain embodiments, the at least one integral abrasive
protrusion comprises an array of integral abrasive protrusions. In
particular embodiments, the array of integral abrasive protrusions
comprises an array of pyramids, tetrahedra, cones, or other
polygons, provided that the pyramids, tetrahedra, cones, or other
polygons have at least one side angled at greater than about 90
degrees relative to the surface of the CMP pad contacted by said
CMP pad conditioning tool.
[0016] In certain embodiments, the material selected from the group
of polycrystalline diamond, polycrystalline cubic boron nitride,
boron carbide, silicon carbide, and combinations thereof is a
SiC-diamond composite.
[0017] The present invention further provides a method for
preparing a CMP pad conditioning tool for conditioning a surface of
a CMP pad. This method comprises machining a surface of a blank
comprising a material selected from the group of polycrystalline
diamond, polycrystalline cubic boron nitride, boron carbide,
silicon carbide, and combinations thereof to produce a CMP pad
conditioning tool according to claim 1.
[0018] In certain embodiments, the machining results in a plurality
of integral abrasive protrusions.
[0019] In certain embodiments, the plurality of protrusions are a
regular array of integral abrasive protrusions.
[0020] In some embodiments, the machining method is wire EDM. In
other embodiments, the machining method is plunge EDM.
[0021] The present invention further includes another method for
preparing the CMP pad conditioning tool described herein. This
method comprises pressing a powder mixture comprising about 90%
diamond powder by weight, about 9.5% silicon powder by weight, and
about 0.5% Si.sub.3N.sub.4 by weight, into a negative form, said
negative form comprising a silicon mass, and heating said powder
and said mass under pressure, to produce the CMP pad conditioning
tool described herein.
[0022] The present invention further includes another method for
preparing the CMP pad conditioning tool described herein. This
method comprises mixing a powder comprising about 90% diamond
powder by weight, about 9.5% silicon powder by weight, and about
0.5% Si.sub.3N.sub.4 by weight, with a binder to form a
powder/binder mixture. The method further includes pressing said
powder/binder mixture to form a preform, said preform having a
preform face, said preform face comprising at least one integral
abrasive protrusion extending from said preform face; heating said
preform to a temperature and in an atmosphere suitable for removing
all of the binder from the preform by incineration; and firing said
preform at a temperature of at least about 1000.degree. C. for at
least about 5 minutes to partially react the powder particles and
form a porous rigid preform.
[0023] In certain embodiments, the binder is polyethyleneglycol or
polyvinylalcohol.
[0024] In some embodiments, the preform is fired at a temperature
of at least about 1450.degree. C. for at least about 5 minutes. In
other embodiments, the preform is fired at a temperature of about
1300.degree. C. for about 5 minutes.
[0025] In certain embodiments, the method further includes heating
the porous rigid preform in an inert gas or under vacuum at a
second temperature; and contacting the rigid porous preform heated
to said second temperature with liquid silicon so that the liquid
silicon infiltrates the preform and reacts with the diamond in the
preform to form SiC.
BRIEF DESCRIPTION OF THE DRAWINGS
[0026] The foregoing summary, as well as the following detailed
description of the embodiments, will be better understood when read
in conjunction with the appended drawings. For the purpose of
illustration, there are shown in the drawings some embodiments
which may be preferable. It should be understood, however, that the
embodiments depicted are not limited to the precise arrangements
and instrumentalities shown.
[0027] FIG. 1 depicts the surface of an SiC-diamond composite CMP
pad conditioning tool wherein the surface of the tool is populated
with an array of evenly distributed square pyramids that are
integral with the surface of the tool.
[0028] FIG. 2 is a schematic representation of the pattern shown on
the surface of the tool depicted in FIG. 1.
[0029] FIG. 3 is a schematic representation of a generalized wire
EDM cutting pattern that can be used to create a variety of arrays
of protrusions.
[0030] FIG. 4 is a schematic representation of a wire EDM cutting
pattern used to arrive at a substrate having the square-pyramid
pattern observed in FIG. 1.
[0031] FIG. 5 is a schematic representation of the angle formed
between an abrasive protrusion of a CMP pad conditioning tool
described herein and a CMP pad being conditioned.
[0032] FIG. 6 is a schematic representation of the pattern as
described in Example 3.
DETAILED DESCRIPTION
[0033] The present disclosure provides a CMP pad conditioning tool
comprising at least one, and in certain embodiments, an array of
fully integral abrasive protrusions that provides more complete
control of the CMP pad reconditioning process. The integral
abrasive protrusions and substrate on which they reside are formed
from a single piece of material, using one of the various processes
described herein. Fashioning the substrate and its protrusions from
a single piece of material negates the need to glue or otherwise
indirectly bond the abrasive protrusions to the substrate on which
they reside. The fully integral protrusions are substantially less
susceptible to abrasive particle loss.
[0034] Without wishing to be bound by any particular theory, it is
believed that the lack of susceptibility to abrasive particle loss
derives at least in part from the inherent strength of the material
used to prepare the substrate and abrasive protrusions, as well as
the resistance of this material to corrosive attack by chemicals in
polishing slurries typically used during the CMP process.
Therefore, when compared to known CMP pad conditioning tools, such
as those described in U.S. Pat. No. 7,641,538, the CMP pad
conditioning tool described herein provides higher abrasive
retention rates and longer tool life. The processes and materials
described herein also allow the aggressiveness of the integral
abrasive protrusions' cutting action to be optimized and
controlled.
[0035] The present disclosure further provides a method of
producing a CMP pad conditioning tool having at least one abrasive
protrusion or an array thereof. For example, the process for
preparing the CMP pad conditioning tool described herein provides
full control over the geometry of the integral abrasive
protrusion(s). The ability to control the height, width, spacing,
and shape of the integral abrasive protrusion(s) eliminates
irregularities common in current conditioning tools and precludes
the need to correct or remove one or more overly aggressive
protrusions common in known random arrays. See, for example, U.S.
Publication 2010/0186479. The tools and methods described herein
also improve the repeatability of the conditioning process.
[0036] In certain embodiments, the CMP pad conditioning tool can be
fabricated from known materials such as polycrystalline diamond
(including Co-bonded polycrystalline diamond and SiC-bonded
diamond), polycrystalline cubic boron nitride, boron carbide,
silicon carbide, combinations thereof, or other extremely hard and
corrosion resistant materials. These hard, corrosion resistant
materials may be presented as single crystal material, as
polycrystalline material, or as a composite.
[0037] For example, in certain embodiments, the CMP pad
conditioning tool can be prepared from an SiC-diamond composite
such as the material described in U.S. Pat. No. 5,106,393, the
entire contents of which are incorporated herein by reference. In
particular embodiments, the SiC-diamond composite can comprise
about 78 weight % to about 82 weight % diamond, about 18 weight %
to about 20 weight % SiC, and, optionally, about 1 weight % to
about 2 weight % un-reacted Si as measured by x-ray
diffraction.
[0038] When Si.sub.3N.sub.4 is included in the mixture of materials
used to prepare the SiC/diamond composite, trace amounts of
nitrogen can infiltrate the molten mixture during processing and
replace carbon. The trace quantities of nitrogen impart electrical
conductivity to the resulting material. The quantity of nitrogen in
the SiC-diamond composite is typically less than about 0.2 weight %
of the total composition. The diamond used in the composite can
include a single grain size, or optionally any combination of grain
sizes, ranging from sub-micron sizes up to about 200 microns.
[0039] In particular embodiments, the SiC-diamond composite can
include a mixture of diamonds of two different grain sizes. In
certain embodiments, the primary diamond grain size can be about 20
microns and the secondary diamond grain size can be about 5
microns. These diamonds can be mixed in a weight ratio of from
about 1:10 to about 10:1. In particular embodiments, the weight
ratio of primary to secondary diamond grain size is about 4:1.
[0040] In certain embodiments, the materials described herein as
suitable for use in the CMP conditioning pad can be produced by CVD
methods. Polycrystalline diamond and cubic boron nitride can be
produced by known HPHT methods. Reaction sintered diamond and cubic
boron nitride composites can be produced by HPHT sintering,
capillary infiltration, reaction sintering, or conventional
sintering. Single crystal conventional abrasives, such as SiC, or
sintered assemblages of abrasive crystals may also be produced by
these methods.
[0041] Any of the materials described herein as suitable for use in
the CMP conditioning pad can be intrinsically conductive, doped to
be made conductive or semiconductive, or comprise a mixture of
materials, one or more of which may be electrically conductive.
Electrical conductivity facilitates plasma machining methods such
arc wire EDM, plunge EDM, formed electrode discharge grinding,
discharge grinding, and similar methods known to those of skill in
the art.
[0042] For non-electrically conductive materials, machining methods
include, but are not limited to, conventional grinding,
lithography, laser ablation, and other conventional methods. These
conventional methods can also be used in conjunction with, or as an
alternative to, plasma machining in samples suitable for plasma
machining.
[0043] A CMP pad conditioning tool prepared using the materials
described herein can include at least one abrasive protrusion but
may include a plurality of protrusions. The protrusions can have
straight, curved, or serrated edges. The protrusions can take the
form any known geometrical shapes, including, but not limited to,
pyramids (including, but not limited to, square pyramids,
triangular pyramids, octagonal, and other polygonal pyramids),
truncated pyramids, tetrahedra, cones (full or truncated),
cylinders, prisms (including, but not limited to, triangular,
rectangular, pentagonal, hexagonal, and any other regular or
irregular prisms), and other polygons.
[0044] Protrusions such as, but not limited to, pyramids, cones,
and tetrahedra may come to a point according to their natural
geometry, or may be truncated or otherwise blunted. In preferred
embodiments, the geometry of the protrusions are such that an angle
between the surface of the CMP pad being conditioned and a surface
of the protrusion is greater than about 90.degree., greater than
about 95.degree., greater than 100.degree., or even greater than
105.degree. or 110.degree.. The angle, .alpha..sub.3, can be
measured as shown in FIG. 5.
[0045] In certain embodiments, the CMP pad conditioning tool can
include an array of abrasive protrusions. The size of the arrayed
protrusions can be varied in plan dimensions and height within a
single tool or from tool to tool. The array can have a periodic
Cartesian nature, rotational symmetry, repeatable semi-random
character, or fully random character. The conditioning tool may
also include penetrations that permit fluids, reactants, and
polishing swarf to be more effectively removed from the tool.
[0046] The protrusions on the CMP pad conditioning tool can be
produced by a number of methods. For example, in certain
embodiments, an SiC-diamond composite having the composition
described previously herein, can be formed with abrasive
protrusions during the material manufacturing process, without the
need for secondary machining. Such a process involves placing the
requisite diamond and silicon powders in contact with a silicon
mass having a negative form of the desired protrusion or array of
protrusions in its surface. The negative form in the silicon
surface can be prepared using known methods including etching,
drilling, laser ablation, and electro discharge machining.
[0047] During the manufacturing process, the diamond and silicon
powder mixture is pressed into the negative form, taking its shape.
At the completion of the manufacturing process, i.e. heating the
powder mixture at temperature under pressure, the resulting
SiC-diamond composite has a surface with protrusions having the
size, shape, and spacing of the corresponding negative form in the
silicon mass.
[0048] CMP pad conditioning tools prepared according to the above
described method can be prepared individually, or in groups, both
according to known processes.
[0049] In other embodiments, an Si--C diamond composite CMP pad
conditioning tool can be prepared by blending the appropriate
silicon and diamond powder mixture with a binder such as PEG
(polyethyleneglycol) or PVA (polyvinylalcohol) so that when pressed
in a die or punch, the powder mixture is consolidated to produce a
"preform." By making a punch or die having an array of depressions
corresponding to the desired protrusion or array of protrusions, a
preform containing the desired surface geometry can be produced.
Optionally, before being compressed into a preform, the powders may
be granulated using a process such as spray drying, freeze
granulation, or other granulation method.
[0050] The preform, still presenting the desired surface geometry,
can then be fired in a furnace having a controlled atmosphere and
temperature in order to remove the binder. In certain embodiments,
the preform is subsequently fired at about 1000.degree. C. so that
some silicon in the preform will react with some diamond in the
preform to produce microscopic amounts of SiC. In some embodiments,
the perform is fired at about 1300.degree. C. for at least about 5
minutes. The microscopic SiC bonds the particles together,
facilitating further processing. The thus fired preform also
contains a matrix of porosity where the binder used to be.
[0051] The fired preform can then be placed in another furnace
wherein it is heated in an inert gas and placed into contact with
liquid silicon so that the silicon infiltrates and fills the pores
within the preform. During the infiltration process, silicon reacts
with diamond in the perform to form SiC to produce a dense body
composed of diamond, SiC, and silicon. In certain embodiments, and
as an alterative to heating under an inert gas, the fired preform
can be heated in a vacuum. Either process results in the formation
of a nearly fully dense body.
[0052] In an alternative embodiment, the preform containing binder
can be fired at a temperature of at least about 1450.degree. C. for
at least about 5 minutes. In a process of this nature, the
conversion of Si to SiC is substantially complete, resulting in a
SiC-diamond composite containing about 20% to about 50% porosity by
volume. The amount of porosity can be controlled by adjusting the
powder composition, powder processing, and preform pressing
parameters.
[0053] Regardless of the process employed, the resulting product
retains the desired surface geometry and is suitable, after any
necessary post processing, for use as a CMP pad conditioning
tool.
[0054] In other embodiments, a CMP pad conditioning tool can be
prepared by preparing the substrate first, and subsequently
machining the substrate to present the desired protrusion or array
of protrusion. For example, an electrically conductive SiC-diamond
composite can be subjected to a plasma machining technique such as
wire EDM to prepare protrusions of varying sizes and
geometries.
[0055] According to the general wire EDM procedure, an electrically
conductive material, such as an SiC-diamond composite described
previously herein, is prepared in a convenient shape or size, such
as a bar with circular, square, hexagonal, or other desired cross
section and appropriate diameter. In certain embodiments, the blank
is mounted in a wire EDM such that it's axis is horizontal.
Subsequently, and in certain embodiments, a first cut can made so
that fresh surface is exposed for further processing.
[0056] In certain embodiments, a series of cuts can be made into
and across the surface of the blank. An exemplary series of cuts is
illustrated schematically in FIG. 3. This series of cuts traverses
across the surface of the blank in one direction and includes at
least one first cut into the surface of the blank at a first angle
.alpha..sub.1 between about 0 and about -90 degrees with respect to
the normal of the blank surface. In particular embodiments,
.alpha..sub.1 can be between about -45 and about 0 degrees. The cut
can progress into the blank to an appropriate depth such as
measured on a line perpendicular to the surface of the blank. This
distance is shown in FIG. 3 as -y2.
[0057] The cut can then proceed parallel to the surface, and at
depth -y2, for a desired distance, x5, wherein x5 can be greater
than or equal to 0. The cut can then proceed out of the blank at a
second angle .alpha..sub.2with respect to the surface normal. In
certain embodiments, .alpha..sub.2can have the same absolute value
as .alpha..sub.1, but have a different sign (i.e. about -30.degree.
and about 30.degree.). In other embodiments, .alpha..sub.1 and
.alpha..sub.2 can be identical. In still other embodiments,
.alpha..sub.1 and .alpha..sub.2 can have different absolute values
and different signs. This series of cuts results in the formation
of a trough in the surface of the blank.
[0058] In certain embodiments, the wire can then be positioned for
a subsequent cut by moving the wire a distance x6, in either the
positive or negative direction, relative to the first series of
cuts, depending upon the type of protrusion that is desired.
Subsequently, in certain embodiments, a second series of cuts can
be made such that a subsequent trough, or series of troughs, are
cut into the surface of the blank. This process can be repeated as
desired, until there is no additional surface area to cut.
[0059] After cutting a desired number of appropriately shaped
troughs in the surface of the blank, the blank can be rotated about
its axis by an angle .beta., and the above described cutting
process can be repeated, such that a second series of troughs are
created at an angle .beta. relative to the first series of troughs.
Depending on the shape, size, and spacing of the protrusions
desired, the rotation .beta. and trough cutting may be repeated
additional times.
[0060] The CMP pad conditioning tool can be incorporated into an
assembly of one or more tools in an equipment module that moves the
tool across the CMP pad surface.
EXAMPLES
[0061] The CMP pad conditioning tool and method for making it
disclosed herein are now further detailed with reference to the
following examples. These examples are provided for the purpose of
illustration only, and the CMP pad conditioning tool and method for
making it should in no way be construed as being limited to these
examples but rather should be construed to encompass any and all
variations which become evident as a result of the teaching
provided herein.
Example 1
[0062] An approximately cylindrical SiC-diamond composite was
prepared according to the following procedure. A mixture comprising
about 90% diamond by weight, about 9.5% Si powder by weight, and
about 0.5% Si.sub.3N.sub.4 by weight was prepared. The diamond
powder included 4 parts of a diamond powder with a particle size of
about 20 microns and 1 part of a diamond powder with an average
particle size of about 5 microns. The Si powder had an average
particle size of less than about 10 microns, and the
Si.sub.3N.sub.4 powder had a particle size of about 1 micron.
[0063] The powder mixture was subsequently loaded into a pressure
cell and placed in contact with a body of silicon. This material
was then subject to HPHT at a pressure of up to about 30 kBar at
about 1600.degree. C. After 30 minutes, the temperature and
pressure were gradually reduced to ambient conditions and an
approximately cylindrical SiC-diamond composite sample was
recovered from the pressure cell.
[0064] The resulting diamond composite comprised approximately
about 78 weight % to about 82 weight % diamond, about 18 weight %
to about 20 weight % of a continuous SiC matrix, about 1 weight %
to 2 weight % un-reacted Si, as determined by x-ray
diffraction.
Example 2
[0065] A CMP pad conditioner having the surface pattern shown in
FIG. 2 was prepared by the following process. All machining was
performed on a Fanuc Robocut alpha-oc wire EDM machine. In the wire
EDM machine, a 0.008'' diameter wire was held in a vertical
orientation, and a cylinder of SiC-diamond composite prepared
according to Example 1 was mounted with the cylinder's axis in a
horizontal orientation. A first cut was made perpendicular to the
cylinder's axis, to expose a fresh surface of SiC-diamond
composite.
[0066] A series of second cuts was then made into and across this
fresh surface. This series of cuts consisted of a cut angled at 30
degrees, 0.5 mm into the surface of the sample; a cut 0.2 mm in
length parallel to the surface of the sample at the 0.5 mm depth;
and a subsequent cut at an angle of -30 degrees out of the surface.
This series of cuts resulted in a trough in the surface of the
SiC-diamond composite. A graphical representation of this cutting
pattern is shown in FIG. 4.
[0067] This series of cuts was repeated across the surface of the
cylinder such that a series of parallel troughs were formed. Next,
the cylinder was rotated by 90 degrees about its axis and a series
of third cuts, identical to the series of second cuts, was made
leaving a matrix of square-pyramid shaped protrusions on the
cylinder surface. A final cut, parallel to the first cut and
perpendicular to the cylinder's axis was then made at an
appropriate distance behind the freshly cut surface to remove a
circular CMP pad conditioning tool from the cylinder of SiC-diamond
composite.
Example 3
[0068] A CMP pad conditioner having the surface pattern shown in
FIG. 6 was prepared by the same process as in Example 2, except for
the following differences.
[0069] A series of second cuts was then made into and across this
fresh surface. This series of cuts consisted of a cut angled at -15
degrees, 0.5 mm into the surface of the sample; a cut 0.18 mm in
length parallel to the surface of the sample at the 0.5 mm depth;
and a subsequent cut at an angle of 15 degrees out of the surface.
This series of cuts resulted in a trough in the surface of the
SiC-diamond composite.
[0070] This series of cuts was repeated across the surface of the
cylinder such that a series of parallel troughs were formed. Next,
the cylinder was rotated by 120 degrees about its axis and a series
of third cuts, identical to the series of second cuts, was made.
Next, the cylinder was rotated again by 120 degrees and a series of
fourth cuts, identical to the series of second and third cuts,
leaving a matrix of triangular-pyramid shaped protrusions on the
cylinder surface. A final cut, parallel to the first cut and
perpendicular to the cylinder's axis was then made at an
appropriate distance behind the freshly cut surface to remove a
circular CMP pad conditioning tool from the cylinder of SiC-diamond
composite.
[0071] While reference has been made to specific embodiments, it is
apparent that other embodiments and variations can be devised by
others skilled in the art without departing from their spirit and
scope. The appended claims are intended to be construed to include
all such embodiments and equivalent variations.
* * * * *