U.S. patent application number 13/696908 was filed with the patent office on 2013-03-07 for fixed abrasive pad with surfactant for chemical mechanical planarization.
This patent application is currently assigned to 3M INNOVATIVE PROPERTIES COMPANY. The applicant listed for this patent is Jimmie R. Baran, JR., Julie Y. Qian. Invention is credited to Jimmie R. Baran, JR., Julie Y. Qian.
Application Number | 20130059506 13/696908 |
Document ID | / |
Family ID | 44383031 |
Filed Date | 2013-03-07 |
United States Patent
Application |
20130059506 |
Kind Code |
A1 |
Qian; Julie Y. ; et
al. |
March 7, 2013 |
FIXED ABRASIVE PAD WITH SURFACTANT FOR CHEMICAL MECHANICAL
PLANARIZATION
Abstract
A fixed abrasive pad (100) in the form of a structured abrasive
article is provided that has a structured abrasive layer (120)
disposed on a backing (110). The structured abrasive layer (120)
includes a polymeric binder, abrasive particles dispersed in the
binder and a nonionic polyether surfactant dispersed in the binder.
The abrasive particles have a mean particle size of less than 200
nm and the surfactant is in the binder in an amount of from 0.75 to
2.2 weight percent based upon the total weight of the structured
abrasive layer. A method of abrading a workpiece using the provided
fixed abrasive pad is also provided.
Inventors: |
Qian; Julie Y.; (Saint Paul,
MN) ; Baran, JR.; Jimmie R.; (Prescott, WI) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Qian; Julie Y.
Baran, JR.; Jimmie R. |
Saint Paul
Prescott |
MN
WI |
US
US |
|
|
Assignee: |
3M INNOVATIVE PROPERTIES
COMPANY
ST. PAUL
MN
|
Family ID: |
44383031 |
Appl. No.: |
13/696908 |
Filed: |
April 29, 2011 |
PCT Filed: |
April 29, 2011 |
PCT NO: |
PCT/US11/34439 |
371 Date: |
November 8, 2012 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61333351 |
May 11, 2010 |
|
|
|
Current U.S.
Class: |
451/59 ;
451/539 |
Current CPC
Class: |
B24B 37/245 20130101;
B24B 37/26 20130101; B24D 3/344 20130101 |
Class at
Publication: |
451/59 ;
451/539 |
International
Class: |
B24B 37/24 20120101
B24B037/24; B24D 3/34 20060101 B24D003/34 |
Claims
1. A structured abrasive article comprising: a backing having first
and second opposed major surfaces; a structured abrasive layer
disposed on and secured to the first major surface wherein the
structured abrasive layer comprises: a polymeric binder; abrasive
particles dispersed in the binder; and a nonionic polyether
surfactant dispersed in the binder, wherein the abrasive particles
have a mean particle size of less than about 200 nm, wherein the
nonionic polyether surfactant is not covalently bound to the
crosslinked polymeric binder, and wherein the nonionic polyether
surfactant is present in an amount of from 0.75 to 2.2 percent by
weight based on a total weight of the structured adhesive
layer.
2. A structured abrasive article according to claim 1, wherein the
nonionic polyether surfactant is present in an amount of from 1.0
to 2.2 percent by weight based on a total weight of the structured
adhesive layer.
3. A structured abrasive article according to claim 1, wherein the
shaped abrasive composites are precisely-shaped.
4. A structured abrasive article according to claim 1, wherein the
crosslinked polymeric binder comprises an acrylic polymer.
5. A structured abrasive article according to claim 1, wherein the
surfactant comprises a polyethylene oxide segment.
6. A structured abrasive article according to claim 1, wherein the
surfactant comprises a polypropylene oxide segment.
7. A structured abrasive article according to claim 1, wherein the
shaped abrasive composites further comprise an anionic phosphate
polyether ester, and wherein the anionic phosphate polyether ester
is present in an amount by weight that is less than that of the
nonionic polyether surfactant.
8. A structured abrasive article according to claim 1, wherein the
backing comprises a polymer film.
9. A structured abrasive article according to claim 8, wherein the
polymer film comprises an elastomeric polyurethane.
10. A structured abrasive article according to claim 1, wherein the
backing comprises a polymer foam.
11. A structured abrasive article according to claim 1, further
comprising an attachment interface layer directly bonded to the
second major surface.
12. A structured abrasive article according to claim 11, wherein
the attachment interface layer comprises a pressure-sensitive
adhesive disposed on the second major surface.
13. A structured abrasive article according to claim 11, wherein
the attachment interface layer comprises a looped fabric.
14. A method of abrading a workpiece comprising: frictionally
contacting at least a portion of a structured abrasive article with
a surface of a workpiece while in the presence of an aqueous fluid;
and moving at least one of the workpiece or the structured abrasive
layer relative to the other to abrade at least a portion of the
surface of the workpiece, wherein the structured abrasive article
comprises: a backing having first and second opposed major
surfaces; and a structured abrasive layer disposed on and secured
to the first major surface wherein the structured abrasive layer
comprises: a polymeric binder; abrasive particles dispersed in the
binder; and a nonionic polyether surfactant dispersed in the
binder, wherein the abrasive particles have a mean particle size of
less than about 200 nm, wherein the nonionic polyether surfactant
is not covalently bound to the crosslinked polymeric binder, and
wherein the nonionic polyether surfactant is present in an amount
of from 0.75 to 2.2 percent by weight based on a total weight of
the structured adhesive layer.
15. A method of abrading a workpiece according to claim 14, wherein
the workpiece is an oxide wafer.
16. A method of abrading a workpiece according to claim 14, wherein
the workpiece comprises silicon.
17. A method of abrading a workpiece according to claim 14, wherein
the aqueous fluid comprises tap water.
Description
FIELD
[0001] The present disclosure broadly relates to abrasive articles,
methods of their manufacture, and their use in wafer
planarization.
BACKGROUND
[0002] Abrasive articles are frequently used in microfinishing
applications such as semiconductor wafer polishing,
microelectromechanical (MEMS) device fabrication, finishing of
substrates for hard disk drives, polishing of optical fibers and
connectors, and the like. For example, during integrated circuit
manufacture, semiconductor wafers typically undergo numerous
processing steps including deposition of metal and dielectric
layers, patterning of the layers, and etching. In each processing
step, it may be necessary or desirable to modify or refine an
exposed surface of the wafer to prepare it for subsequent
fabrication or manufacturing steps. The surface modification
process is often used to modify deposited conductors (e.g., metals,
semiconductors, and/or dielectric materials). The surface
modification process is also typically used to create a planar
outer exposed surface on a wafer having an exposed area of a
conductive material, a dielectric material, or a combination.
[0003] One method of modifying or refining exposed surfaces of
structured wafers treats a wafer surface with a fixed abrasive
article. In use, the fixed abrasive article is typically contacted
with a semiconductor wafer surface, often in the presence of a
working fluid, with a motion adapted to modify a layer of material
on the wafer and provide a planar, uniform wafer surface. The
working fluid may be applied to the surface of the wafer to
chemically modify or otherwise facilitate the removal of material
from the surface of the wafer under the action of the abrasive
article.
[0004] Fixed abrasive articles generally have an abrasive layer of
abrasive particles bonded together by a binder and secured to a
backing In one type of fixed abrasive article, the abrasive layer
is composed of discrete raised structural elements (e.g., posts,
ridges, pyramids, or truncated pyramids) termed "shaped abrasive
composites". This type of fixed abrasive article is known in the
art variously by the terms "textured, fixed abrasive article" or
"structured abrasive article" (this latter term shall be used
hereinafter). The abrasive articles can include abrasive particles
and at least one nonionic polyether surfactant dispersed in a
crosslinked polymer binder as disclosed in U.S. Ser. No. 12/560,797
(Woo et al.).
[0005] In order to assess progress during the planarization process
it is common practice to use various detection methods. Optical
detection methods (e.g., laser interferometry) are among the most
widely used. In such techniques, a laser is typically directed
through windows in a platen and a subpad in contact with the
structured abrasive article. A hole or transparent (uncoated with
abrasive layer) portion of the structured abrasive article is
aligned with the beam.
SUMMARY
[0006] Chemical mechanical planarization (CMP) processes can cause
non-uniformity of polished wafers. There is a need for fixed
abrasive articles that provide excellent wafer uniformity and high
polish rates. There is a need for fixed abrasive articles that are
useful for the fabrication of electronic components that have very
small nodes. For example, dynamic random access memory (DRAM) and
flash memory devices can have nodes of 32 nm or even 28 nm. There
is a need for fixed abrasive articles that can rapidly polish
semiconductor wafers having small nodes without causing defects
that can produce channel-to-channel short-circuits.
[0007] It has been found that by using very small abrasive
particles and a surfactant included in the structured adhesive
layer that excellent wafer uniformity and high polish rates of
wafers can be achieved. In one aspect, a structured abrasive
article is provided that includes a backing having first and second
opposed major surfaces, a structured abrasive layer disposed on and
secured to the first major surface wherein the structured abrasive
layer comprises a polymeric binder, abrasive particles dispersed in
the binder, and a nonionic polyether surfactant dispersed in the
binder, wherein the abrasive particles have a mean particle size of
less than about 200 nm, wherein the nonionic polyether surfactant
is not covalently bound to the crosslinked polymeric binder, and
wherein the nonionic polyether surfactant is present in an amount
of from 0.75 to 2.2 percent by weight based on a total weight of
the structured adhesive layer. The shaped abrasive composites can
be precisely-shaped. The binder can include an acrylic polymer. The
surfactant can include a polyethylene oxide or a polypropylene
oxide segment. The backing can be an elastomeric polyurethane film
or a polymer foam.
[0008] In another aspect, a method of abrading a workpiece is
provided that includes frictionally contacting at least a portion
of a structured abrasive article with a surface of a workpiece
while in the presence of an aqueous fluid and moving at least one
of the workpiece or the structured abrasive layer relative to the
other to abrade at least a portion of the surface of the workpiece,
wherein the structured abrasive article includes a backing having
first and second opposed major surfaces and a structured abrasive
layer disposed on and secured to the first major surface wherein
the structured abrasive layer includes a polymeric binder, abrasive
particles dispersed in the binder, and a nonionic polyether
surfactant dispersed in the binder,
[0009] wherein the abrasive particles have a mean particle size of
less than about 200 nm, wherein the nonionic polyether surfactant
is not covalently bound to the crosslinked polymeric binder, and
wherein the nonionic polyether surfactant is present in an amount
of from 0.75 to 2.2 percent by weight based on a total weight of
the structured adhesive layer.
[0010] The aqueous fluid can include tap water.
[0011] As used herein:
[0012] the term "abrasive particle" refers to any particle having a
hardness equal or greater to that of ceria;
[0013] the term "fixed abrasive pad" and "structured abrasive
article" are used interchangeably;
[0014] the term "at least translucent" means translucent or
transparent;
[0015] the term "carboxylic(meth)acrylate" means a compound having
a (meth)acrylate group covalently linked to a carboxyl
(--CO.sub.2H) or carboxylate (--CO.sub.2--) group;
[0016] the term "visible light" refers to light having a wavelength
in a range of from 400 nanometers to 700 nanometers, inclusive;
[0017] the term "(meth)acryl" includes acryl and/or methacryl;
[0018] the term "optical transmission" means the fraction of
incident light transmitted through an object;
[0019] the term "poly(meth)acrylate" means a compound having at
least two (meth)acrylate groups;
[0020] the term "transparent" means capable of transmitting visible
light so that objects or images can be seen substantially as if
there were no intervening material; and
[0021] the terms "cerium oxide" and "ceria" refer to
Ce(IV)O.sub.2.
[0022] The above summary is not intended to describe each disclosed
embodiment of every implementation of the present invention. The
brief description of the drawings and the detailed description
which follows more particularly exemplify illustrative
embodiments.
BRIEF DESCRIPTION OF THE DRAWINGS
[0023] FIG. 1 is a perspective view of an exemplary structured
abrasive article according to one embodiment according to the
present disclosure.
[0024] FIG. 2 is a schematic side view of an exemplary method of
conditioning a surface of a wafer according to the present
disclosure.
[0025] FIG. 3 is a graph of the removal rate of oxide as a function
of cross-sectional wafer diameter using provided articles and
methods.
DETAILED DESCRIPTION
[0026] In the following description, reference is made to the
accompanying set of drawings that form a part of the description
hereof and in which are shown by way of illustration several
specific embodiments. It is to be understood that other embodiments
are contemplated and may be made without departing from the scope
or spirit of the present invention. The following detailed
description, therefore, is not to be taken in a limiting sense.
[0027] Unless otherwise indicated, all numbers expressing feature
sizes, amounts, and physical properties used in the specification
and claims are to be understood as being modified in all instances
by the term "about." Accordingly, unless indicated to the contrary,
the numerical parameters set forth in the foregoing specification
and attached claims are approximations that can vary depending upon
the desired properties sought to be obtained by those skilled in
the art utilizing the teachings disclosed herein. The use of
numerical ranges by endpoints includes all numbers within that
range (e.g. 1 to 5 includes 1, 1.5, 2, 2.75, 3, 3.80, 4, and 5) and
any range within that range.
[0028] Referring now to FIG. 1, structured abrasive article 100
comprises at least translucent film backing 110. Abrasive layer 120
is disposed on at least translucent film backing 110 and comprises
a plurality of shaped abrasive composites 130. Shaped abrasive
composites 130 comprise abrasive particles (not shown) dispersed in
a binder (not shown). The abrasive particles consist essentially of
ceria particles having an average primary particle size of less
than 100 nanometers. The binder comprises a polyether acid and a
reaction product of components comprising a carboxylic
(meth)acrylate and a poly(meth)acrylate, and wherein based on a
total weight of the abrasive layer, the abrasive particles are
present in an amount of at least 70 percent by weight.
[0029] The translucent film backing may be flexible, rigid, or in
between. A variety of backing materials are suitable for this
purpose, including both flexible backings and backings that are
more rigid. Useful translucent film backings include backing films
selected from polymer films, treated versions thereof, and
combinations thereof. Exemplary translucent backing films include
films made from polyester (e.g., polyethylene terephthalate or
polycaprolactone), co-polyester, polycarbonate, polyimide,
polyamide, polypropylene, polyurethane, polyethylene, cellulosic
polymers, and blends and combinations thereof. In some embodiments,
the backing can include an elastomeric urethane or a foam.
[0030] The thickness of the translucent film backing is typically
in a range of from about 20 to about 1000 micrometers, more
typically, from about 50 micrometers to about 500 micrometers, and
more typically from about 60 micrometers to about 200 micrometers.
At least one surface of the backing may be coated with the abrasive
layer. In general, the backing is of substantially uniform in
thickness. If the backing is not sufficiently uniform in thickness,
greater variability in wafer polishing uniformity may occur during
wafer planarization.
[0031] The abrasive layer includes a plurality of shaped abrasive
composites. As used herein, the term "shaped abrasive composite"
refers to one of a plurality of shaped bodies comprising abrasive
particles dispersed in a binder, the shaped bodies collectively
providing a textured, three-dimensional abrasive layer. In some
embodiments, the shaped abrasive composites are "precisely-shaped".
The term "precisely-shaped abrasive composite" refers to an
abrasive composite having a molded shape that is substantially the
inverse of a mold cavity used to make it. Typically,
precisely-shaped abrasive composites are substantially free of
abrasive particles protruding beyond the exposed surface of the
abrasive composite before the structured abrasive article has been
used.
[0032] Provided structured abrasive articles can have a high weight
content of shaped abrasive particles in the abrasive layer. For
example the shaped abrasive composites comprise, on a weight basis,
at least 70 percent of the abrasive layer; and may comprise at
least 75, 80, or even 90 percent by weight of the abrasive layer,
or more. Typically, a higher weight percentage of the abrasive
particles in the shaped abrasive composites results in higher
cut.
[0033] The abrasive particles can include ceria (i.e., cerium
oxide) particles having an average particle size, on a volume
basis, of less than 250 nanometers, less than 150 nanometers, less
than 100 nanometers, or even less than 50 nanometers. The abrasive
particles can consist essentially of ceria particles. The phrase
"consist essentially of" used in this context is intended to
exclude other (i.e., non-ceria) abrasive particles in amounts that
materially affect abrading properties of the structured abrasive
article, if used in wafer planarization of silicon-containing
wafers. It will be recognized that that the ceria particles may
comprise agglomerates and/or aggregates of smaller primary ceria
particles. For example, the ceria particles (whether present as
primary particle, agglomerates, aggregates, or a combination
thereof) may have an average particle size, on a volume basis, in a
range of from 1, 5, 10, 20, 30, or 40 nanometers up to 50, 60, 70,
80, 90, 95 nanometers, or more.
[0034] The ceria particles can be supplied, for example, in the
form of a powder, dispersion, or sol; typically, as a dispersion or
sol. Methods and sources for obtaining ceria sols having an average
particle size less than 250 nanometers are well known in the art.
Ceria dispersions and sols suitable for use in the present
disclosure include, for example, ceria sols and dispersions
commercially available for suppliers such as Evonik Degussa Corp.
of Parsippany, N.J.; Rhodia, Inc. of Cranberry, N.J.; Ferro
Corporation of Independence, Ohio; and Umicore SA, Brussels,
Belgium.
[0035] The abrasive particles may be homogeneously or
heterogeneously dispersed in the polymeric binder. The term
"dispersed" refers to the abrasive particles being distributed
throughout the polymeric binder. Dispersing the ceria particles
substantially homogeneously in the binder typically increases
performance of the structured abrasive article. Accordingly, it is
typically useful to treat the ceria particles with
carboxylic(meth)acrylates to facilitate their dispersibility and/or
reduce aggregation, and enhance subsequent coupling to the binder.
Exemplary carboxyli(meth)acrylates include (meth)acrylic acid,
monoalkyl esters of maleic acid, fumaric acid, monoalkyl esters of
fumaric acid, maleic acid, itaconic acid, isocrotonic acid,
crotonic acid, citraconic acid, and
.beta.-carboxyethyl(meth)acrylate.
[0036] In one exemplary method for treating the ceria particles
with a carboxylic (meth)acrylate, a dispersion (e.g., a sol) of the
ceria particles in an aqueous medium (e.g., water) is combined with
a polyether acid and carboxylic(meth)acrylate (in amounts of each
that are sufficient to surface treat and thereby stabilize the
ceria particles) and a water-miscible organic solvent having a
higher boiling point than water. Typically, the proportion of
polyether acid to carboxylic(meth)acrylate is in a range of from
about 3:5 to 5:3, although other proportions may be used. Examples
of useful solvents include 1-methoxy-2-propanol, dimethylformamide,
and diglyme. Once combined, the water is substantially removed by
evaporation under reduced pressure resulting in a ceria dispersion
in which the ceria particles are stabilized against aggregation by
associated carboxylic(meth)acrylate molecules. The resultant ceria
dispersion can typically be readily combined with the
poly(meth)acrylate and optional mono(meth)acrylate monomers, and
any additional carboxylic(meth)acrylate that may be included in the
binder precursor.
[0037] While the carboxylic(meth)acrylate typically serves to
facilitate bonding of the ceria particles to the binder, the
polyether acid is included primarily to facilitate dispersion
stability of the ceria particles in the binder (or its precursor
components) and/or solvent. As used herein, the term "polyether
acid" refers to a compound having a polyether segment covalently to
an acidic group or salt thereof. Exemplary polyether segments
include polyethylene glycol segments, polyethylene glycol segments,
and mixed poly(ethylene glycol/propylene glycol) segments.
Exemplary acidic groups include --CO.sub.2H, --PO.sub.2H,
--PO.sub.3H, --SO.sub.3H, and salts thereof. In certain
embodiments, the polyether acids can have up to 12 carbon atoms,
inclusive, and are represented by the formula:
R.sup.1--(R.sup.2--O).sub.n--X-A
wherein R.sup.1 represents H, an alkyl group having from 1 to 6
carbon atoms (e.g., methyl ethyl, or propyl), or an alkoxy group
having from 1 to 6 carbon atoms (e.g., methoxy, ethoxyl, or
propoxy); each R.sup.2 independently represents a divalent alkylene
group having from 1 to 6 carbon atoms (e.g., ethylene, propylene,
or butylene); n represents a positive integer (e.g., 1, 2, or 3;
and X represents a divalent organic linking group or a covalent
bond; and A represents an acidic group (e.g., as described
hereinabove). Exemplary such polyether acids include
2'-(2''-methoxyethoxy)ethyl succinate (monoester),
methoxyethoxyethoxyacetic acid, and methoxyethoxyacetic acid. The
binder can further include a reaction product of components
comprising a carboxylic(meth)acrylate and a poly(meth)acrylate. As
discussed above, at least a portion of the carboxylic(meth)acrylate
is typically combined with the abrasive particles prior to
combining the resultant dispersion with the remaining binder
components, although this is not a requirement.
[0038] A nonionic polyether surfactant is dispersed in the binder.
Typically, there is no covalent chemical bond between the
surfactant and the binder. The binder can be crosslinked as
described further on to help contain the surfactant and regulate
its release. The amount of polyether nonionic surfactant present in
the shaped abrasive composites can be in a range of from 0.75 to
2.2, from 1.0 to 2.2, from 1.3 to 2.2 percent by weight, typically
from 1.5 to 2.0 percent by weight, based on a total weight of the
shaped abrasive composites. As used herein, the term "polyether
nonionic surfactant" refers to one or more nonionic (i.e., not
having a permanent charge) surfactant(s) that has/have a polyether
segment, typically forming at least a portion of the backbone of
the surfactant, although this is not a requirement. As is generally
the case for surfactants, the polyether nonionic surfactant should
not be covalently bound to the crosslinked polymeric binder. To
facilitate dissolution into the aqueous fluid, the polyether
nonionic surfactant typically has a molecular weight in a range of
from 300-1200 grams per mole, although higher and lower molecular
weights may be used.
[0039] Examples of polyether nonionic surfactants include
polyoxyethylene alkyl ethers, polyoxyethylene alkyl-phenyl ethers,
polyoxyethylene acyl esters, polyoxyethylene alkylamines,
polyoxyethylene alkylamides, polyoxyethylene lauryl ether,
polyoxyethylene cetyl ether, polyoxyethylene stearyl ether,
polyoxyethylene oleyl ether, polyoxyethylene octylphenyl ether,
polyoxyethylene nonylphenyl ether, polyethylene glycol laurate,
polyethylene glycol stearate, polyethylene glycol distearate,
polyethylene glycol oleate, oxyethylene-oxypropylene block
copolymer, polyoxyethylene sorbitan laurate, polyoxyethylene
sorbitan stearate, polyoxyethylene sorbitan oleate, and
polyoxyethylene laurylamide.
[0040] Useful polyether nonionic surfactants also include, for
example, condensation products of a higher aliphatic alcohol with
about 3 equivalents to about 100 equivalents of ethylene oxide
(e.g., those marketed by Dow Chemical Co. under the trade
designation TERGITOL 15-S such as, for example, TERGITOL 15-S-20;
and those marketed by ICI Americas of Bridgewater, N.J. under the
trade designation BRIJ such as, for example, BRIJ 58, BRIJ 76, and
BRIJ 97). BRIJ 97 surfactant is polyoxyethylene (10) oleyl ether;
BRIJ 58 surfactant is polyoxyethylene (20) cetyl ether; and BRIJ 76
surfactant is polyoxyethylene (10) stearyl ether.
[0041] Useful polyether nonionic surfactants also include, for
example, polyethylene oxide condensates of an alkyl phenol with
about 3 equivalents to about 100 equivalents of ethylene oxide
(e.g., those marketed by Rhodia of Cranbury, N.J. under the trade
designations IGEPAL CO and IGEPAL CA). IGEPAL CO surfactants
include nonylphenoxy poly(ethyleneoxy)ethanols. IGEPAL CA
surfactants include octylphenoxy poly(ethyleneoxy)ethanols. Useful
polyether nonionic surfactants also include, for example, block
copolymers of ethylene oxide and propylene oxide or butylene oxide
(e.g., those marketed by BASF Corp. of Mount Olive, N.J. under the
trade designations PLURONIC (e.g., PLURONIC L10) and TETRONIC).
PLURONIC surfactants may include propylene oxide polymers, ethylene
oxide polymers, and ethylene oxide-propylene oxide block
copolymers. TETRONIC surfactants include ethylene oxide-propylene
oxide block copolymers.
[0042] In some embodiments, polyether nonionic surfactants can
include polyoxyethylene sorbitan fatty acid esters (e.g.,
polyoxyethylene sorbitan monooleates), which may have differing
degrees of ethoxylation such as, for example, 20 ethylene oxide
units per molecule (e.g., marketed as TWEEN 60) or 20 ethylene
oxide units per molecule (e.g., marketed as TWEEN 80)) and
polyoxyethylene stearates (e.g., those marketed under the trade
designations TWEEN and MYRJ by Uniqema of New Castle, Del.). TWEEN
surfactants include poly(ethylene oxide) C.sub.12-C.sub.18 sorbitan
monoesters. MYRJ surfactants include poly(ethylene oxide)
stearates.
[0043] In some embodiments, the polyether nonionic surfactant is
the only surfactant present in the shaped abrasive composites or in
the aqueous fluid during abrading. In some cases, it may be
desirable to add lesser quantities of anionic surfactants such as
an anionic phosphate polyether ester available as TRITON H55 from
Dow Chemical Co.
[0044] The abrasive layer includes abrasive particles dispersed in
a binder. Suitable binder precursors are typically, in an uncured
or uncrosslinked state, flowable at or near ambient conditions. The
binder precursor is then typically exposed to conditions (typically
an energy source) that at least partially cure or crosslink (i.e.,
free-radical polymerization) the binder precursor, thereby
converting it into a binder capable of retaining the dispersed
abrasive particles. Exemplary energy sources include: e-beam,
ultraviolet radiation, visible radiation, infrared radiation, gamma
radiation, heat, and combinations thereof.
[0045] Useful poly(meth)acrylates include monomers and/or oligomers
that have at least two (meth)acrylate groups; for example,
tri(meth)acrylates, and tetra(methacrylates). Exemplary
poly(methacrylates) include: di(meth)acrylates such as, for
example, 1,3-butylene glycol di(meth)acrylate, 1,4-butanediol
di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, 1,6-hexanediol
mono(meth)acrylate mono(meth)acrylate, ethylene glycol
di(meth)acrylate, alkoxylated aliphatic di(meth)acrylate,
alkoxylated cyclohexanedimethanol di(meth)acrylate, alkoxylated
hexanediol di(meth)acrylate, alkoxylated neopentyl glycol
di(meth)acrylate, caprolactone modified neopentyl glycol
hydroxypivalate di(meth)acrylate, caprolactone modified neopentyl
glycol hydroxypivalate di(meth)acrylate, cyclohexanedimethanol
di(meth)acrylate, diethylene glycol di(meth)acrylate, dipropylene
glycol di(meth)acrylate, ethoxylated (10) bisphenol A
di(meth)acrylate, ethoxylated (3) bisphenol A di(meth)acrylate,
ethoxylated (30) bisphenol A di(meth)acrylate, ethoxylated (4)
bisphenol A di(meth)acrylate, hydroxypivalaldehyde modified
trimethylolpropane di(meth)acrylate, neopentyl glycol
di(meth)acrylate, polyethylene glycol (200) di(meth)acrylate,
polyethylene glycol (400) di(meth)acrylate, polyethylene glycol
(600) di(meth)acrylate, propoxylated neopentyl glycol
di(meth)acrylate, tetraethylene glycol di(meth)acrylate,
tricyclodecanedimethanol di(meth)acrylate, triethylene glycol
di(meth)acrylate, tripropylene glycol di(meth)acrylate;
tri(meth)(meth)acrylates such as glycerol tri(meth)acrylate,
trimethylolpropane tri(meth)acrylate, ethoxylated
tri(meth)acrylates (e.g., ethoxylated (3) trimethylolpropane
tri(meth)acrylate, ethoxylated (6) trimethylolpropane
tri(meth)acrylate, ethoxylated (9) trimethylolpropane
tri(meth)acrylate, ethoxylated (20) trimethylolpropane
tri(meth)acrylate), pentaerythritol tri(meth)acrylate, propoxylated
tri(meth)acrylates (e.g., propoxylated (3) glyceryl
tri(meth)acrylate, propoxylated (5.5) glyceryl tri(meth)acrylate,
propoxylated (3) trimethylolpropane tri(meth)acrylate, propoxylated
(6) trimethylolpropane tri(meth)acrylate), trimethylolpropane
tri(meth)acrylate, tris(2-hydroxyethyl)isocyanurate
tri(meth)acrylate; and higher functionality (meth)acryl containing
compounds such as ditrimethylolpropane tetra(meth)acrylate,
dipentaerythritol penta(meth)acrylate, ethoxylated (4)
pentaerythritol tetra(meth)acrylate, pentaerythritol
tetra(meth)acrylate, caprolactone modified dipentaerythritol
hexa(meth)acrylate; oligomeric (meth)acryl compounds such as, for
example, polyester (meth)acrylates, epoxy(meth)acrylates; and
combinations thereof. Such compounds are widely available from
vendors such as, for example, Sartomer Co. of Exton, Pa.; UCB
Chemicals Corporation of Smyrna, Ga.; and Aldrich Chemical Company
of Milwaukee, Wis.
[0046] The binder precursor may comprise an effective amount of at
least one photoinitiator; for example, in an amount of from 0.1, 1,
or 3 percent by weight, up to 5, 7, or even 10 percent by weight,
or more. Useful photoinitiators include those known as useful for
free-radically photocuring (meth)acrylates. Exemplary
photoinitiators include benzoin and its derivatives such as
alpha-methylbenzoin; alpha-phenylbenzoin; alpha-allylbenzoin;
alpha-benzylbenzoin; benzoin ethers such as benzil dimethyl ketal
(available as IRGACURE 651 from Ciba Specialty Chemicals,
Tarrytown, N.Y.), benzoin methyl ether, benzoin ethyl ether,
benzoin n-butyl ether; acetophenone and its derivatives such as
2-hydroxy-2-methyl-1-phenyl-1-propanone (available as DAROCUR 1173
from Ciba Specialty Chemicals) and 1-hydroxycyclohexyl phenyl
ketone (available as IRGACURE 184 from Ciba Specialty Chemicals);
2-methyl-1-[4-(methylthio)phenyl]-2-(4-morpholinyl)-1-propanone
(available as IRGACURE 907 from Ciba Specialty Chemicals);
2-benzyl-2-(dimethylamino)-1-[4-(4-morpholinyl)phenyl]-1-butanone
(available as IRGACURE 369 from Ciba Specialty Chemicals); and
(phenyl bis(2,4,6-trimethylbenzoyl) phosphine oxide (available as
IRGACURE 819 from Ciba Specialty Chemicals, NY. Other useful
photoinitiators include mono- and bis-acylphosphines (available,
for example, from Ciba Specialty Chemicals as IRGACURE 1700,
IRGACURE 1800, IRGACURE 1850, and DAROCUR 4265).
[0047] The binder precursor may comprise an effective amount of at
least one thermal initiator; for example, in an amount of from 0.1,
1, or 3 percent by weight, up to 5, 7, or even 10 percent by
weight, or more. Exemplary thermal free-radical initiators include:
azo compounds such as, for example, 2,2-azo-bisisobutyronitrile,
dimethyl 2,2'-azobis(isobutyrate), azobis(diphenyl methane),
4,4'-azobis-(4-cyanopentanoic acid),
(2,2'-azobis(2,4-dimethylvaleronitrile (available as VAZO 52 from
E.I. du Pont de Nemours and Co. of Wilmington, Del.); peroxides
such as, for example, benzoyl peroxide, cumyl peroxide, tert-butyl
peroxide, cyclohexanone peroxide, glutaric acid peroxide, and
dilauryl peroxide; hydrogen peroxide; hydroperoxides such as, for
example, tert butyl hydroperoxide and cumene hydroperoxide;
peracids such as, for example, peracetic acid and perbenzoic acid;
potassium persulfate; and peresters such as, for example,
diisopropyl percarbonate.
[0048] In some embodiments, it may be desirable to include one or
more monoethylenically unsaturated free-radically polymerizable
compounds in the binder precursor; for example, to reduce viscosity
and/or or reduce crosslink density in the resultant binder.
Exemplary monoethylenically unsaturated free-radically
polymerizable compounds include: mono(meth)acrylates include
hexyl(meth)acrylate, 2-ethylhexyl acrylate, isononyl(meth)acrylate,
isobornyl(meth)acrylate, phenoxyethyl(meth)acrylate,
2-hydroxyethyl(meth)acrylate, dodecyl(meth)acrylate,
methyl(meth)acrylate, ethyl(meth)acrylate, n-propyl(meth)acrylate,
n-butyl(meth)acrylate, n-octyl(meth)acrylate,
isobutyl(meth)acrylate, cyclohexyl(meth)acrylate, or
octadecyl(meth)acrylate; N-vinyl compounds such as, for example,
N-vinylformamide, N-vinylpyrrolidinone, or N-vinylcaprolactam; and
combinations thereof.
[0049] In some embodiments, the abrasive layer may also include one
additives. The additives can include one or more of an antioxidant,
a colorant, a heat and light stabilizer, or a filler (the filler
having substantially no impact on abrading performance).
Accordingly, the binder is typically prepared from a binder
precursor comprising the abrasive particles, the surfactant, and
additives in which the abrasive particles are dispersed (e.g., as a
slurry).
[0050] Provided structured abrasive articles, that include shaped
abrasive composites, can be made by general methods well-known in
the art. For example, in one embodied method a binder precursor and
abrasive particles, in the form of a slurry, can be urged into
complementary cavities in a production tool that have the
dimensions of the desired shaped abrasive composites. Then, the
translucent film backing can brought into contact with the
production tool and slurry precursor and the binder precursor can
be at least sufficiently cured to remove the shaped abrasive
composites from the production tool. Alternatively, the production
tool, at least translucent film backing, and slurry can be
simultaneously fed through a nip. Optionally, further curing (e.g.,
thermal post curing) can be carried out at this stage to further
advance the degree of cure and thereby improve the binder
properties. Further details concerning methods for forming shaped
abrasive composites can be found in, for example, U.S. Pat. No.
5,152,917 (Pieper et al.).
[0051] Individual shaped abrasive composites can have the form of
any of a variety of geometric solids or be irregularly shaped.
Typically, the shaped abrasive composites are precisely-shaped (as
defined above). Typically, the shaped abrasive composite is formed
such that the base of the shaped abrasive composite, for example,
that portion of the shaped abrasive composite is in contact with,
and secured to, the at least translucent film backing The proximal
portion of the shaped abrasive composite typically has the same or
larger a larger surface area than that portion of the shaped
abrasive composite distal from the base or backing Precisely-shaped
abrasive composites may be selected from among a number of
geometric solids such as a cubic, cylindrical, prismatic (e.g.,
hexagonal prisms), rectangular pyramidal, truncated pyramidal,
conical, hemispherical, truncated conical, cross, or post-like
cross sections with a distal end. Composite pyramids may have four
sides, five sides or six sides. The shaped abrasive composites may
also have a mixture of different shapes. The shaped abrasive
composites may be arranged in rows, in concentric circles, in
helices, or in lattice fashion, or may be randomly placed.
[0052] The sides forming the shaped abrasive composites may be
perpendicular relative to the backing, tilted relative to the
backing or tapered with diminishing width toward the distal end.
However, if the sides are tapered, it may be easier to remove the
shaped abrasive composite from the cavities of a mold or production
tool. The substantially perpendicular angles are preferred because
this results in a consistent nominal contact area as the composite
wears.
[0053] The height of each shaped abrasive composite is typically
substantially the same, but it is envisaged to have composites of
varying heights in a single structured abrasive article. The height
of the composites with respect to the backing or to the land
between the composites generally may be less than about 2,000
micrometers; for example, in a range of from about 10 micrometers
to about 250 micrometers. The base dimension of an individual
shaped abrasive composite may be about 5,000 micrometers or less,
typically about 1,000 micrometers or less, more typically less than
500 micrometers. The base dimension of an individual shaped
abrasive composite is typically greater than about 50 micrometers,
more typically greater than about 100 micrometers. The base of the
shaped abrasive composites may abut one another, or may be
separated from one another by some specified distance.
[0054] Adjacent shaped composites may share a common shaped
abrasive composite land or bridge-like structure which contacts and
extends between facing sidewalls of the composites. Typically, the
land structure has a height of no greater than about 33 percent of
the vertical height dimension of each adjacent composite. The
shaped abrasive composite land may be formed from the same slurry
used to form the shaped abrasive composites. The composites are
"adjacent" in the sense that no intervening composite may be
located on a direct imaginary line drawn between the centers of the
composites. At least portions of the shaped abrasive composites may
be separated from one another so as to provide the recessed areas
between the raised portions of the composites.
[0055] The linear spacing of the shaped abrasive composites may
range from about 1 shaped abrasive composite per linear cm to about
200 shaped abrasive composites per linear cm. The linear spacing
may be varied such that the concentration of composites may be
greater in one location than in another. For example, the
concentration may be greatest in the center of the abrasive
article. The areal density of the composite may range, in some
embodiments, from about 1 to about 40,000 composites per square
centimeter. One or more areas of the backing may be exposed, i.e.,
have no abrasive coating contacting the at least translucent film
backing
[0056] The shaped abrasive composites are typically set out on a
backing in a predetermined pattern or set out on a backing at a
predetermined location. For example, in the abrasive article made
by providing slurry between the backing and a production tool
having cavities therein, the predetermined pattern of the
composites will correspond to the pattern of the cavities on the
production tool. The pattern may be thus reproducible from article
to article. In one embodiment, the shaped abrasive composites may
form an array or arrangement, by which may be meant that the
composites are in a regular array such as aligned rows and columns,
or alternating offset rows and columns. If desired, one row of
shaped abrasive composites may be directly aligned in front of a
second row of shaped abrasive composites. Typically, one row of
shaped abrasive composites may be offset from a second row of
shaped abrasive composites.
[0057] In another embodiment, the shaped abrasive composites may be
set out in a "random" array or pattern. By this it may be meant
that the composites are not in a regular array of rows and columns
as described above. For example, the shaped abrasive composites may
be set out in a manner as disclosed in U.S. Pat. Nos. 5,672,097 and
5,681,217 (both Hoopman et al.). It will be understood, however,
that this "random" array may be a predetermined pattern in that the
location of the composites on the abrasive article may be
predetermined and corresponds to the location of the cavities in
the production tool used to make the abrasive article.
[0058] Exemplary production tools include rolls, endless belts, and
webs, and may be made of an suitable material such as for example,
metal (e.g., in the case of rolls) or polymer films (e.g., in the
cases of endless belts and webs).
[0059] Provided structured abrasive articles may be generally
circular in shape, e.g., in the form of an abrasive disc. Outer
edges of the abrasive disc are typically smooth, or may be
scalloped. The structured abrasive articles may also be in the form
of an oval or of any polygonal shape such as triangular, square,
rectangular, and the like. Alternatively, the abrasive articles may
be in the form of a belt. The abrasive articles may be provided in
the form of a roll, typically referred to in the abrasive art as
abrasive tape rolls. In general, the abrasive tape rolls may be
indexed or moved continuously during the wafer planarization
process. The abrasive article may be perforated to provide openings
through the abrasive coating and/or the backing to permit the
passage of the working fluid before, during and/or after use;
although, in advantageous embodiments the structured abrasive
articles are substantially free of, or even completely free of,
such perforations.
[0060] Precisely-shaped abrasive composites may be of any
three-dimensional shape that results in at least one of a raised
feature or recess on the exposed surface of the abrasive layer.
Useful shapes include, for example, cubic, prismatic, pyramidal
(e.g., square pyramidal or hexagonal pyramidal), truncated
pyramidal, conical, frustoconical. Combinations of differently
shaped and/or sized abrasive composites may also be used. The
abrasive layer of the structured abrasive may be continuous or
discontinuous. Further details concerning structured abrasive
articles having precisely-shaped abrasive composites, and methods
for their manufacture may be found, for example, in U.S. Pat. No.
5,435,816 (Spurgeon et al.); U.S. Pat. No. 5,454,844 (Hibbard et
al.); U.S. Pat. No. 5,851,247 (Stoetzel et al.); and U.S. Pat. No.
6,139,594 (Kincaid et al.).
[0061] Typically, the shaped abrasive composites are arranged on
the backing according to a predetermined pattern or array, although
this is not a requirement. The shaped abrasive composites may be
arranged such that some of their work surfaces are recessed from
the polishing surface of the abrasive layer.
[0062] The translucent film backing of the structured abrasive
articles can typically be contacted with a subpad during use. In
some cases, the structured abrasive article can be secured to the
subpad. The abrasive layer can be applied to a front surface of the
at least translucent film backing and an adhesive, for example a
pressure-sensitive adhesive (or mechanical fastening device) can be
applied to the opposing surface of the at least translucent film
backing Suitable subpads are disclosed, for example, in U.S. Pat.
Nos. 5,692,950 and 6,007,407 (both to Rutherford et al.). If using
optical detection methods, the subpad, and any platen on which it
rests, should have at least one appropriately sized window (e.g.,
an opening or transparent insert) to permit a continuous optical
path from a light source (e.g., a laser) through the platen and
subpad.
[0063] Provided structured abrasive articles can be fabricated such
that they have sufficient optical transmittance to be suitable for
use with optical detection methods such as, for example, laser
interferometry. For example, the structured abrasive article may
have an optical transmission of at least 1.5, 2.0, 2.5, 3.0, 3.5,
4.0, 4.5, or even 5.0 percent, or more, over any wavelength range;
for example, corresponding to the output wavelength of a laser.
Exemplary laser wavelengths include: 694 nm (ruby), 676.4 nm
(Kr-ion), 647.1 nm (Kr-ion), 635-660 nm (InGaAlP semiconductor),
633 nm (HeNe), 628 nm (ruby), 612 nm (HeNe), 578 (Cu vapor), 568.2
nm (Kr-ion), 543 nm (HeNe), 532 nm (DPSS semiconductor), 530.9 nm
(Kr-ion), 514.5 nm (Ar-ion), 511 nm (Cu vapor), 501.7 nm (Ar),
496.5 nm (Ar), 488.0 nm (Ar), 476.5 nm (Ar), 457.9 nm (Ar), 442 nm
(HeCd), or 428 nm (N.sub.2.sup.+).
[0064] Provided structured abrasive articles may be used for
abrading and/or polishing workpieces such as wafers containing
silicon (e.g., silicon wafers, glass wafers, etc.) or other metals
and including those wafers having an oxide layer on an outer
surface thereof. For example, the structured abrasive articles may
be useful in abrading and/or polishing a dielectric material
deposited on the wafer and/or the wafer itself. Additionally, it is
contemplated that the provided abrasive article can be useful in
abrading or polishing other materials such as sapphire or other
minerals. Variables that affect the wafer polishing rate and
characteristics include, for example, the selection of the
appropriate contact pressure between the wafer surface and abrasive
article, type of working fluid, relative speed and relative motion
between the wafer surface and the abrasive article, and the flow
rate of the working fluid. These variables are interdependent, and
are typically selected based upon the individual wafer surface
being processed.
[0065] Structured abrasive articles according to the present
disclosure may be conditioned, for example, by abrading the surface
using a pad conditioner (e.g., with diamond grits held in a metal
matrix) prior to and/or intermittently during the wafer
planarization process. One useful conditioner is a CMP pad
conditioner (typically mounted on a rigid backing plate), part no.
CMP-20000TS, available from Morgan Advanced Ceramics of Hayward,
Calif.
[0066] In general, since there can be numerous process steps for a
single semiconductor wafer, the semiconductor fabrication industry
expects that the process will provide a relatively high removal
rate of material. The material removal rate obtained with a
particular abrasive article will typically vary depending upon the
machine conditions and the type of wafer surface being processed.
However, although it is typically desirable to have a high
conductor or dielectric material removal rate, the conductor or
dielectric material removal rate may be selected such that it does
not compromise the desired surface finish and/or topography of the
wafer surface.
[0067] Referring now to FIG. 2, in an exemplary method of
conditioning a surface of a wafer, structured abrasive article 100
contacts and is secured to subpad 210, which is in turn secured to
platen 220. Subpad 210, which may comprise a foam (e.g., a
polyurethane foam) or other compressible material, has first window
212 therein, and platen 220 has second window 222 therein. Wafer
holder 233 is mounted to a head unit 231 that is connected to a
motor (not shown). Gimbal chuck 232 extends from head unit 231 to
wafer holder 233. Wafer holder 233 helps secure wafer 240 to head
unit 231 and also prevent the semiconductor wafer from becoming
dislodged during planarization. Wafer holder 233 extends alongside
of wafer 240 at ring portion 233a. Ring portion 233a (which is
optional) may be a separate piece or may be integral with wafer
holder 233. Wafer 240 is brought into contact with the abrasive
layer 120 of structured abrasive article 100, and the wafer 240 and
abrasive layer 120 are moved relative to one another. The progress
of polishing/abrading is monitored using laser beam 250 which
passes through second window 222, first window 212, and structured
abrasive article 100 and is reflected off oxide surface 242 wafer
240 and then retraces its path. Optional working fluid 260 may be
used to facilitate the abrading process. Reservoir 237 holds
optional working fluid 260 which is pumped through tubing 238 into
the interface between semiconductor wafer and the abrasive layer.
Useful working fluids include, for example, those listed in U.S.
Pat. No. 5,958,794 (Bruxvoort et al.).
[0068] In general, wafer surface finishes that are substantially
free of scratches and defects are desired. The surface finish of
the wafer may be evaluated by known methods. One method is to
measure the Rt value, which provides a measure of roughness, and
may indicate scratches or other surface defects. The wafer surface
is typically modified to yield an Rt value of no greater than about
0.4 nanometers, more typically no greater than about 0.2
nanometers, and even more typically no greater than about 0.05
nanometers. Rt is typically measured using a laser interferometer
such as a Wyko RST PLUS interferometer (Wyko Corp., Tucson, Ariz.),
or a Tencor profilometer (KLA-Tencor Corp., San Jose, Calif.).
Scratch detection may also be measured by dark field microscopy.
Scratch depths may be measured by atomic force microscopy.
[0069] Wafer surface processing may be conducted in the presence of
a working fluid, which may be selected based upon the composition
of the wafer surface. In some applications, the working fluid
typically comprises water. The working fluid may aid processing in
combination with the abrasive article through a chemical mechanical
polishing process. During the chemical portion of polishing, the
working fluid may react with the outer or exposed wafer surface.
Then during the mechanical portion of processing, the abrasive
article may remove this reaction product.
[0070] The current trend in memory storage devices and other
electronics is miniaturization. There is a need for abrasive
articles that can polish wafers that have very small nodes without
producing defects. Some exemplary devices have nodes as small as 32
nm or even 28 nm. To polish these wafers it is important that the
abrasive article be able to create a smooth surface with very few
defects at a relatively high rate. In addition, the wafer, which
can be There is a need for abrasive articles that can polish wafers
that have very small nodes without producing defects. Some
exemplary devices have nodes as small as 32 nm or even 28 nm. To
polish these wafers it is important that the abrasive article be
able to create a smooth surface with very few defects at a
relatively high rate. In addition after polishing, the wafer, which
can be 100 mm or more in diameter, needs to have a uniform profile
with minimal dishing (more wear at the edges than at the center).
It has been surprisingly found that structured abrasive articles
that include a polymeric binder which has abrasive particles and a
nonionic polyether surfactant dispersed therein can remove material
from thermal oxide wafers at rates exceeding 1500 .ANG./min when
the abrasive particles have a mean particle size of less than about
200 nm, less than about 150 nm, less than 140 nm, or even less than
130 nm and when the nonionic polyether surfactant is present in an
amount of from 0.75 to 2.2, from 1.0 to 2.2, from 1.3 to 2.2 or
even from 1.5 to 2.0 percent by weight of the structured adhesive.
Table 1 in the Example section illustrates this result. The
provided abrasive articles have a special combination of abrasive
particle size, amount of nonionic polyether surfactant, and
construction such that the surfactant is dispersed in a crosslinked
binder in the proper amount to allow for high wafer removal rates
with low defects and excellent cross-wafer uniformity.
[0071] Objects and advantages of this disclosure are further
illustrated by the following non-limiting examples, but the
particular materials and amounts thereof recited in these examples,
as well as other conditions and, details, should not be construed
to unduly limit this disclosure.
EXAMPLES
Example 1
Fixed Abrasive Web with 1% Surfactant
Preparation of Ceria Dispersion 1
[0072] A ceria dispersion (11.4045 kg, 51.06% solids in water, 132
nm average particle size, available from Ferro Corporation of
Independence, Ohio) was poured into a mixing vessel and then 703
grams of 2-(2-methoxyethoxy)ethoxyacetic acid, 568 grams of
.beta.-carboxyethyl acrylate (acid #5.9-6.0), and 2.7907 kg of
1-methoxy-2-propanol were slowly added while mixing using a
polytetrafluoroethylene-coated blade. The mixture was heated to
50.degree. C. and mixed overnight. The mixture was then transferred
into a rotary evaporator and excess water was removed under reduced
pressure. The resultant dispersion had a solids content of 49.32
percent.
Preparation of Slurry 1
[0073] Into a mixing vessel were mixed 45.000 kg Ceria Dispersion
1, 665.8 grams of DISPERBYK-111 wetting and dispersing additive
(available from BYK-Chemie USA, Inc. of Wallingford, Conn.). To
this mixture was added 125.9 grams of 2-hydroxyethyl methacrylate
(available from Rohm and Haas Co. of Philadelphia, Pa.), 318.7
grams of 2-phenoxyethyl acrylate (available as SR 339, from
Sartomer Co. or Exton, Pa.)), 2.445 kg of trimethylolpropane
triacrylate (available as SR 351 from Sartomer Co.), 137.1 grams of
.beta.-carboxyethyl acrylate (available from Bimax Inc. of
Cockeysville, Md.), 252.2 grams TERGITAL 15-7-S (available from
Sigma Aldrich Inc.,) and 15.13 grams of phenothiazine dissolved in
466.1 grams of 1-methoxy-2-propanol. The mixture was mixed using a
polytetrafluoroethylene-coated blade for 30 minutes, then
transferred to a rotary evaporator to remove the
1-methoxy-2-propanol. The slurry was cooled to room temperature,
and then 26.16 grams of free-radical photoinitiator (phenyl
bis(2,4,6-trimethylbenzoyl)phosphine oxide, available as IRGACURE
819 from Ciba Specialty Chemicals of Tarrytown, N.Y.), 26.16 grams
of thermal free-radical initiator
(2,2'-azobis(2,4-dimethylvaleronitrile, available as VAZO 52 from
E.I. du Pont de Nemours and Co. of Wilmington, Del.) and 6.54 grams
of hydroquinone monomethyl ether were added, followed by mixing for
two hours.
Example 1
[0074] A roll of polypropylene production tool, 30 inches (76 cm)
in width, was provided. The polypropylene production tool was
polypropylene film that had a hexagonal array (350 micrometers on
center) of hexagonal columnar cavities (125 .mu.m wide and 30 .mu.m
deep), corresponding to a 10 percent cavitation area. The
production tool was essentially the inverse of the desired shape,
dimensions, and arrangement for the abrasive composites in the
ultimate structured abrasive article. Method 4 disclosed in U.S.
Pat. No. 7,497,885 (Kollodge) provides a further description of the
tool and its use. Slurry 1 was coated between the cavities of
production tool and roll of translucent polycarbonate/PBT based
film backing material (7 mils (0.18 mm) thickness available as
BAYFOL CR6-2 from Bayer Corp., Pittsburgh, Pa.) using a casting
roll and a nip roll (nip force of 1300 pounds (5.78 kN)) and then
passed through UV light source (V Bulb, Model EPIQ available from
Fusion Systems), at a line speed of 10 feet/min (3.0 m/min) and a
total exposure of 6.0 kilowatts/inch (2.36 kJ/hr-cm). The resultant
structured abrasive article (SA1) was removed from the production
tool after being UV cured.
[0075] SA1 was used to polish thermal oxide blanket wafers (200 mm
in diameter with a micrometer film thickness of silicon oxide on
its surface) using CMP polisher available under the trade
designation REFLEXION polisher from Applied Materials, Inc. of
Santa Clara, Calif. using a wafer pressure of 3.0 lb/in.sup.2 (20.7
kPa), a platen speed of 30 revolutions per minute, and a web index
speed of 8 millimeters for 1 minute. The measured removal rate
averaged 1625 A/min for thermal oxide wafers, with an unexpected
center fast wafer profile, as shown in the graph above, which
provides an option to fine tone the wafer profile to its optimal
uniformity by adjusting pressures applying to the wafers.
Example 2
Fixed Abrasive Web with 2% Surfactant
Preparation of Ceria Dispersion 2
[0076] A ceria dispersion (102.195 kg, 51.56% solids in water, 135
nm average particle size, available from Ferro Corporation of
Independence, OH) was poured into a mixing vessel and then 622
grams of 2-(2-methoxyethoxy)ethoxyacetic acid, 503 grams of
.beta.-carboxyethyl acrylate acid, and 2.4752 kg of
1-methoxy-2-propanol were slowly added while mixing using a
polytetrafluoroethylene-coated blade. The mixture was heated to
50.degree. C. and mixed overnight. The mixture was then transferred
into a rotary evaporator and excess water was removed under reduced
pressure. The resultant dispersion had a solids content of 49.13
percent.
Preparation of Slurry 2
[0077] Into a mixing vessel were mixed 45.000 kg Ceria Dispersion
2, 733.8 grams of DISPERBYK-111 wetting and dispersing additive
(available from BYK-Chemie USA, Inc. of Wallingford, Conn.). To
this mixture was added 125.4 grams of 2-hydroxyethyl methacrylate
(available from Rohm and Haas Co. of Philadelphia, Pa.), 317.5
grams of 2-phenoxyethyl acrylate (available as SR 339, from
Sartomer Co. or Exton, Pa.,)), 2.435 kg of trimethylolpropane
triacrylate (available as SR 351 from Sartomer Co.), 136.6 grams of
.beta.-carboxyethyl acrylate (available from Bimax Inc. of
Cockeysville, Md.), 502.5 grams TERGITOL 15-7-S (available from
Sigma Aldrich Inc.,) and 15.07 grams of phenothiazine dissolved in
464.3 grams of 1-methoxy-2-propanol. The mixture was mixed using a
polytetrafluoroethylene-coated blade for 30 minutes, and then
transferred to a rotary evaporator to remove the
1-methoxy-2-propanol. The slurry was cooled to room temperature,
and then 27.0 grams of free-radical photoinitiator (phenyl
bis(2,4,6-trimethylbenzoyl)phosphine oxide, available as Ciba
IRGACURE 819 from Ciba Specialty Chemicals of Tarrytown, N.Y.),
27.0 grams of thermal free-radical initiator
(2,2'-azobis(2,4-dimethylvaleronitrile, available as VAZO 52 from
E. I. du Pont de Nemours and Co. of Wilmington, Del.) and 6.75
grams of hydroquinone monomethyl ether were added, followed by
mixing for two hours.
Example 2
[0078] A roll of polypropylene production tool, 30 inches (76 cm)
in width, was provided. The polypropylene production tool was
polypropylene film that had a hexagonal array (350 .mu.m on center)
of hexagonal columnar cavities (125 .mu.m wide and 30 micrometers
deep), corresponding to a 10 percent cavitation area. The
production tool was essentially the inverse of the desired shape,
dimensions, and arrangement for the abrasive composites in the
ultimate structured abrasive article. SLURRY 2 was coated between
the cavities of production tool and roll of translucent
polycarbonate/PBT based film backing material (7 mils (0.18 mm)
thickness available a BAYFOL CR6-2 from Bayer Corp., Pittsburgh,
Pa.) using a casting roll and a nip roll (nip force of 1300 pounds
(5.78 kN)) and then passed through UV light source (V Bulb, Model
EPIQ available from Fusion Systems), at a line speed of 10 feet/min
(3.0 m/min) and a total exposure of 6000 watts/inch (2.36
kJ/hr-cm). The resultant structured abrasive article (SA2) was
removed from the production tool after being UV cured.
[0079] SA2 was used to polish thermal oxide blanket wafers (200 mm
in diameter with a micrometer film thickness of silicon oxide on
its surface) using CMP polisher available under the trade
designation REFLEXION polisher from Applied Materials, Inc. of
Santa Clara, Calif. using a wafer pressure of 3.0 lb/in.sup.2 (20.7
kPa), a platen speed of 30 revolutions per minute, and a web index
speed of 8 millimeters for 1 minute. The measured removal rate
averaged 2011 .ANG./min for thermal oxide wafers, with an
unexpected center fast wafer profile, as shown in the graph above,
which provides an option to fine tone the wafer profile to its
optimal uniformity by adjusting pressures applying to the
wafers.
Comparative Example 1
Fixed Abrasive Web Without Surfactant
Preparation of Slurry 3
[0080] Into a mixing vessel were mixed 45.000 kg Ceria Dispersion
2, 663.3 grams of DISPERBYK-111 wetting and dispersing additive
(available from BYK-Chemie USA, Inc. of Wallingford, Conn.). To
this mixture was added 125.4 grams of 2-hydroxyethyl methacrylate
(available from Rohm and Haas Co. of Philadelphia, Pa.), 317.5
grams of 2-phenoxyethyl acrylate (available as SR 339, from
Sartomer Co. or Exton, Pa.)), 2.4354 kg of trimethylolpropane
triacrylate (available as SR 351 from Sartomer Co.), 136.6 grams of
.beta.-carboxyethyl acrylate (available from Bimax Inc. of
Cockeysville, Md.), and 15.07 grams of phenothiazine dissolved in
464.3 grams of 1-methoxy-2-propanol. The mixture was mixed using a
polytetrafluoroethylene-coated blade for 30 minutes, then
transferred to a rotary evaporator to remove the
1-methoxy-2-propanol. The slurry was cooled to room temperature,
and then 20.04 grams of free-radical photoinitiator (phenyl
bis(2,4,6-trimethylbenzoyl)phosphine oxide, available as Ciba
IRGACURE 819 from Ciba Specialty Chemicals of Tarrytown, N.Y.),
20.04 grams of thermal free-radical initiator
(2,2'-azobis(2,4-dimethylvaleronitrile, available as VAZO 52 from
E.I. du Pont de Nemours and Co. of Wilmington, Del.) and 5.01 grams
of hydroquinone monomethyl ether were added, followed by mixing for
two hours.
Comparative Example 1
[0081] A roll of polypropylene production tool, 30 inches (76 cm)
in width, was provided. The polypropylene production tool was
polypropylene film that had a hexagonal array (350 .mu.m on center)
of hexagonal columnar cavities (125 .mu.m wide and 30 .mu.m deep),
corresponding to a 10 percent cavitation area. The production tool
was essentially the inverse of the desired shape, dimensions, and
arrangement for the abrasive composites in the ultimate structured
abrasive article. Slurry 3 was coated between the cavities of
production tool and roll of translucent polycarbonate/PBT based
film backing material (7 mils (0.18 mm) thickness available as
BAYFOL CR6-2 from Bayer Corp., Pittsburgh, Pa.) using a casting
roll and a nip roll (nip force of 1300 pounds (5.78 kN)) and then
passed through UV light source (V Bulb, Model EPIQ available from
Fusion Systems), at a line speed of 10 feet/min (3.0 m/min) and a
total exposure of 6000 watts/inch (2.36 kJ/hr-cm). The resultant
structured abrasive article (SA3) was removed from the production
tool after being UV cured.
[0082] SA3 was used to polish thermal oxide blanket wafers (200 mm
in diameter with a micrometer film thickness of silicon oxide on
its surface) using CMP polisher available under the trade
designation REFLEXION polisher from Applied Materials, Inc. of
Santa Clara, Calif. using a wafer pressure of 3.0 lb/in.sup.2 (20.7
kPa), a platen speed of 30 revolutions per minute, and a web index
speed of 5 millimeters for 1 minute. The measured removal rate
averaged 742 .ANG./min for thermal oxide wafers, with a typical
center slow and edge fast cross wafer profile, which is hard to
overcome, as shown in the graph above.
Comparative Example 2
Fixed Abrasive Web with 3% Surfactant
Preparation of Slurry 4
[0083] Into a mixing vessel were mixed 1.0747 kg Ceria Dispersion
2, 15.8 grams of DISPERBYK-111 wetting and dispersing additive
(available from BYK-Chemie USA, Inc. of Wallingford, Conn.). To
this mixture was added 3.00 grams of 2-hydroxyethyl methacrylate
(available from Rohm and Haas Co. of Philadelphia, Pa.), 7.58 grams
of 2-phenoxyethyl acrylate (available as SR 339, from Sartomer Co.
or Exton, Pa.)), 58.16 grams of trimethylolpropane triacrylate
(available as SR 351 from Sartomer Co.), 3.26 grams of
.beta.-carboxyethyl acrylate (available from Bimax Inc. of
Cockeysville, Md.), 18.0 grams TERGITAL 15-7-S (available from
Sigma Aldrich Inc.,) and 0.36 grams of phenothiazine dissolved in
20 grams of 1-methoxy-2-propanol. The mixture was mixed using a
polytetrafluoroethylene-coated blade for 30 minutes, and then
transferred to a rotary evaporator to remove the
1-methoxy-2-propanol. The slurry was cooled to room temperature,
and then 0.65 grams of free-radical photoinitiator (phenyl
bis(2,4,6-trimethylbenzoyl)phosphine oxide, available as IRGACURE
819 from Ciba Specialty Chemicals of Tarrytown, N.Y.), 0.65 grams
of thermal free-radical initiator
(2,2'-azobis(2,4-dimethylvaleronitrile, available as VAZO 52 from
E.I. du Pont de Nemours and Co. of Wilmington, Del.) and 0.16 grams
of hydroquinone monomethyl ether were added, followed by mixing for
two hours.
[0084] A roll of polypropylene production tool, 30 inches (76 cm)
in width, was provided. The polypropylene production tool was
polypropylene film that had a hexagonal array (350 micrometers on
center) of hexagonal columnar cavities (125 micrometers wide and 30
micrometers deep), corresponding to a 10 percent cavitation area.
The production tool was essentially the inverse of the desired
shape, dimensions, and arrangement for the abrasive composites in
the ultimate structured abrasive article. Slurry 4 was coated
between the cavities of production tool and roll of translucent
polycarbonate/PBT based film backing material (7 mils (0.18 mm)
thickness available a BAYFOL CR6-2 from Bayer Corp., Pittsburgh,
Pa.) using a casting roll and a nip roll (nip force of 1300 pounds
(5.78 kN)) and then passed through UV light source (V Bulb, Model
EPIQ available from Fusion Systems), at a line speed of 10 feet/min
(3.0 m/min) and a total exposure of 6000 watts/inch (2.36
kJ/hr-cm). The resultant structured abrasive article (SA4) was
removed from the production tool after being UV cured.
[0085] SA4 was used to polish thermal oxide blanket wafers (200 mm
in diameter with a micrometer film thickness of silicon oxide on
its surface) using CMP polisher available under the trade
designation REFLEXION polisher from Applied Materials, Inc. of
Santa Clara, Calif. using a wafer pressure of 3.0 lb/in.sup.2 (20.7
kPa), a platen speed of 30 revolutions per minute, and a web index
speed of 8 millimeters for 1 minute. The film was found to fall
apart during the polish, and was unable to polish the wafers.
Comparative Example 3
Surfactant Added to Polish Fluid
[0086] SA3 was used to polish thermal oxide blanket wafers (200 mm
in diameter with a micrometer film thickness of silicon oxide on
its surface) using CMP polisher available under the trade
designation REFLEXION polisher from Applied Materials, Inc. of
Santa Clara, Calif. using a wafer pressure of 3.0 lb/in.sup.2 (20.7
kPa), a platen speed of 30 revolutions per minute, and a web index
speed of 5 millimeters for 1 minute. An amount of TERGITOL was
added the polish fluid equivalent to that in the FA web in Example
2, based on the calculations. The measured removal rate averaged
793 .ANG./min for thermal oxide wafers, with a typical center slow
and edge fast cross wafer profile as shown in FIG. 3.
[0087] The removal rates of the Examples and Comparative Examples
are displayed in Table 1.
TABLE-US-00001 TABLE 1 Removal Rate on Thermal Oxide Wafers
Examples Surfactant Removal Rate (A/min) Example 1 Tergitol at 1%
based on total 1625 (Resin + Abrasive) Example 2 Tergitol at 2%
based on total 2011 (Resin + Abrasive) Comparative 1 None 742
Comparative 2 Tergitol at 3% Fixed abrasive based on total film
fall apart (Resin + Abrasive) during polishing Comparative 3
Tergitol added into polish fluid 793
[0088] Various modifications and alterations to this invention will
become apparent to those skilled in the art without departing from
the scope and spirit of this invention. It should be understood
that this invention is not intended to be unduly limited by the
illustrative embodiments and examples set forth herein and that
such examples and embodiments are presented by way of example only
with the scope of the invention intended to be limited only by the
claims set forth herein as follows. All references cited in this
disclosure are herein incorporated by reference in their
entirety.
* * * * *